CnrtifU 3lntet0itjj THE CALDWELL COLLECTION THE GIFT OF THE FAMILY OF GEORGE CHAPMAN .CALDWELL TO THE D^ARTMENT OF CHEMISTRY whose senior Professor he was from (868 to }903 Cornell University Library RS 403.B28 Text-book of medical chemistry tor medic 3 1924 003 468 190 Cornell University Library rv!5< The original of tliis book is in tlie Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924003468190 MEDICAL CHEMISTRY. BARTLEY. 5 — i -^ 1 ^ 1 1 1 1 1 1 1 1 s = 1 ^^H a 1 lllllllll ^H ^H ^H ■ ^1 n - ^9 5 = 1 — 1 L^a — = .B ^^^^1^^ m ^3 ^H hH ^ ==s - m v=\ 1 =^ ^ M ^m == g — 1 ^d 1 ■- iN ... jO = d 1 ^ ^m 8 1 ri ^^^ H ^^s ^ ^ Q? 1 -1 1^=^ r" 1 1 ^ ^^^^^ ^ — = - ^ ■^H == * = ■ ~S ■ a "n = ^N ^s = ■ ^ = = a — = ■■^ ^^^MW^^^ M— ■ t-« M CO 'J' to CO f 00 &> o r-l 1 ^ to •a il 1 t- ABSORPTION Spectra. EXPLANATION. i s. "o 1. E si 1 o % ■S e — < 0) a tti3 Id II 1 11 ■3 u > « "5 o y < I t) c H 'c o E e a.S c3 O o o 1 s ■s c" ■^ S 5 . c rt S 8i ,s ■a Sj 6) 7> atoms of hydrogen or their equivalent. The chemical equivalent of an atom, is an atom which can take its place in a molecule. Atoms are divided into monads, dyads, triads, tetrads, pentads, hexads, or heptads, according as they can fix i, 2, 3, 4, 5, 6, or 7 atoms of hydrogen, or their equivalent. Univalent, bivalent, trivalent, etc., are adjectives used to express the valence of an atom. A monad is equivalent to a monad. " dyad " " to 2 monads. " triad " " to 3 " or i monad and i dyad. " tetrad " " to 4 " 2 dyads, or i monad and 1 triad. A pentad " " to 5 " a tetrad and i monad, a triad and 2 monads, or 2 dyads and i monad. The valence of an atom is often indicated to the eye by dashes, thus: — I Monad O— Dyad — O— Triad — O— I \l/ \/ \l/ Tetrad — O— Pentad O Hexad — O— Heptad — O— I /\ /\ /\ It will be seen that the hydrogen atom is the unit of comparison for combining powers, or valences, and the dashes represent the number of bonds or points of attraction, or poles of the atomic magnet. The valence of an atom may also be ex- pressed by a Roman numeral placed above and to the right, thus :— H-, O", Cl'°, C", etc. CHEMICAL NOTATION. 96. Symbols and Formulae. — In representing atoms and molecules to the eye, we make use of a series of symbols derived from the names of the elements themselves. This is usually the initial letter of the English or Latin name, or in case two or more names begin with the same letter, the initial with some other characteristic letter. Thus, on reference to the table in Art. 87, we see B, Ba, Bi, Br, representing the atoms of boron, barium, bismuth, and bromine respectively. In this book, a 86 MEDICAL CHEMISTRY. symbol is never used to represent the element in general, but a symbol always represents an atom, with all its properties, and nothing else. Formulae. — A formula is the sign of a molecule. It, there- fore, represents a definite weight — the molecular weight ; and in the case of gases, always the same volume. Formulae are made up of symbols, as a molecule is made up of atoms ; and the atoms composing a molecule are all represented by symbols in the formula. Thus: HCl is a formula representing a molecule containing one atom or i part of hydrogen, and one atom or 35.5 parts of chlorine. In writing formulae, we write the symbols composing the mole- cule in juxtaposition, beginning with the more electro-positive. Thus : KOCl, HBr, etc. Multiplication of Molecules and Atoms.— When we wish to represent more than one atom, we use a small numeral at the right hand lower corner of the symbol ; thus, Oj, represents 2 atoms of oxygen, or, since the molecule of oxygen contains two atoms, this also represents the molecule. Asj represents 4 atoms of arsenic, or since the molecule of arsenic contains four atoms, it is also the formula of a molecule of arsenic. When we wish to represent more than one molecule of a substance, we use full-sized numerals placed before the formula. Thus, 2H2O represents two molecules, each of which is com- posed of two atoms of hydrogen and one of oxygen. Or, we may enclose the formula in a parenthesis, and place a small numeral at the right hand lower corner, thus : (H20)2. Ex- amples: — H2SO4 represents i molecule, containing 2 atoms of hydrogen, I of sulphur, and 4 of oxygen. 5H2SO4 represents 5 molecules of the same substance. 3NHjNC>3 represents 3 molecules, containing in each molecule two atoms of nitrogen, 4 atoms of hydrogen, and 3 atoms of oxygen ; 27 atoms in all. 2KjAl2 (SOj)^ represents two molecules, containing in each molecule 2 atoms of potassium, 2 atoms of aluminium, 4 atoms of sulphur, and 16 atoms of oxygen ; 48 atoms in all. As the symbols always represent the atomic weights, we may reduce any formula to figures, or find its molecular weight, by adding together the weights represented by the symbols compos- ing it. Let it be desired to find the molecular weight of HjSOi. By reference to the table in Art. 87, it will be seen that H2 = 2, S = 32 and O4 =~ 4X16 = 64. By adding together these three numbers we obtain 98, the weight of the molecule. CHEMICAL NOTATION. S7 An empirical formula is one which merely gives the kind and number of the atoms composing a molecule. A rational or graphic formula aims .to show the arrangement of the atoms in the molecule, with relation to one another. Examples of empirical formulEe : — IINO3, IIjSOj, CuSO^, NajCO.,, HjPO,, CH^, C^HfiH, CO,. Rational formulae for the same : — O H-0-P_0-H "-C-H C=5 „ 0=C=0 I H -— O Rational formulae are useful in giving us a more definite con- ception of the relations of the atom? to one another in the molecule. They have served as the guides in some of the most important chemical discoveries of the present century; such as the discovery of the process of manufacturing artificial madder and indigo from coal tar products, by synthesis. 97. Variation in Equivalence. — By graphic formulae we are able to explain a fact that is always a matter of difficulty to the student, viz. : the variation in the equivalence of atoms. There are two well known series of salts of mercury and copper, in which there is no real variation ; but, owing to the uniting of two atoms of the metals, each loses an available bond or point of attraction. The following formulae will render this clear : — Hg— CI. Cu— CI. 01— Hg— CI and | CI— Cu— CI and | Hg— CI. Cu— CI. In other cases, and under certain well known conditions which we can control in the laboratory, the atom which has previously existed as a dyad suddenly becomes a tetrad, or a triad becomes a pentad, and so on. These changes are always extremely puzzling to the student, and we shall dwell a little upon them. When ammonia gas (NH3), for example, is absorbed by water, it combines with a MEDICAL CHEMISTRY. molecule of the water and becomes NH^OH. 'If we represent the two molecules graphically, we have, N-H i-i_0--iT-H. _H ana H_(|-H. As will be seen, two new points of attraction have made their appearances upon the nitrogen atom. A large number of such cases are known, and the explanation is as follows : — The full equivalence of nitrogen is pentad. In the compound H3N, for some unknown reason, two poles of the atomic magnet neutralize each other, and so the combining power of the atom is lessened by two. This increase or diminution of combining power always takes place in pairs, so that a dyad may become a tetrad, but not a triad. A monad may become a triad or a pentad, but never a dyad or tetrad. 98. Other Signs Used in Writing. — A plus sign between two formulse indicates that the substances, whose molecules they represent, are brought together. The minus sign indicates that the molecule following it is abstracted from the preceding one. The sign of equality is used to indicate that what follows, is the result of some change that has taken place. HCl + AgNOg = HNO3 + AgCl shows that the molecules represented by the first two formulae have been brought together, and that a change has taken place result- ing in the formation of the two last. 99. Compound Radicals. — A radical or root of a series of compounds is a characteristic atom or group running through all of them, like a root in language. Thus the interrogative root wh runs through all that class of words, as who, which, when, w^hat, etc. So, in chemical compounds we have a large number of potassium compounds, in which the atom K appears as the characteristic atom : As KNOg, KCIO3, K2CO3, K2SO4, and KCl. It is therefore called the root or radi- cal of these compounds. A single atom, which forms a series of characteristic compounds, is called a simple radical. Sometimes, instead of being a single atom, it is a group of atoms that is found to be the characteristic of a series of com- pounds. Thus, we have: (NH4)N03, (NH,)C1, (NH^NOa, (NH4)2S, etc., in which the characteristic radical is a group of atoms, or is a compound radical. A compound radical may be regarded as a group of atoms which behaves like a simple radical, or single atom. Like the CHEMICAL NOTATION. EQUIVALENCE OF THE ELEMENTS. 89 Monads. Dyads. Triads. Tetrads. Pentads. Hexads. Oxygen . .0 Sulphur . . S Sulphur . b Sulphur . . S Nitrogen . N Fluorine F Nitrogen . N Chlorine CI Bromine Br Phosphorus P Phosphorus P Iodine . I Arsenic . . As Boron . . B Antimony . Sb Carbon . C Silicon . . Si Arsenic . . As Chromium . Cr Manganese Mn Hydrogen H Mercury . He Gold . . . Au Bismuth . 6i Platinum . Pt Tin .... Sn Iron . . . Fe Silver Ag Cadmium . Cobalt Nickel . . Iron . . . Chromium Manganese Zinc . . . Magnesium Calcium Strontium Barium Cu Ph Cd Co Ni Fe Cr Mn Zn Mg Ca Sr Ba Chromium Cr ManganeseMn .Muminium Al Sodium Na Potassium K CHARACTERISTIC GROUPS OF ATOMS WITH NAMES OF COMPOUNDS THEY FORM. Monads. Dyads. Triads. Tetrads. NOs = Nitrates C103= Chlorates NO2 — Nitrites CIO — Hypochlorites PH0O2 = Hypophos- phites. CN — Cyanides. C2H3O2— Acetates C7H5O2 = Benzoates C7H4O3 = Salicylates CsHjO = Carbolales C3H5OS — Lactates HO = Hydroxides NFT4 = Ammonium CH3— Methyl C2H5= Ethyl SO4 _ Sulphates Cr04 — Chromates Cr207 = Bichromates SO3- Sulphites C2O4 _ Oxalates C4H,06 — Tartrates CjH.Os-Malates CO3 = Carbonates Hg2= Mercurous Salts Cu2 = Cuprous Salts P04= Phosphates AsOs = Arsenites ASO4 = Arsenates BO3 = Borates Si04 = Silicates P2O7 = Pyrophosphates FeCye = Ferrocyanides Hexads. Fe2Cyio = Ferricyanides A\.i= Aluminic Salts Crg = Chromic " Mn2= Manganic" Feg = Ferric " go MEDICAL CHEMISTRY. single atom, it exists only in combination with another atom or group of atoms, for its bonds or points of attraction are not satisfied unless it be in combination. Compound radicals, like atoms, may be positive or negative. Each com'{)ound radical has a definite equivalence, like the atoms. Some of them have re- ceived arbitrary names which do not express their composition, and in most cases end In yl. Thus, (PO)'" phosphoryl, (H-O-)' hodroxyl, (CO)" carbonyl, (CHaV methyl, (C^H^)' ethyl, (H^N)' ammonium, (CN)' cyanogen. (NHa)' amidogen. The last three are exceptions to the rule as to the ending. In writing the formula of these compound radicals, they may be regarded for the time as atoms of a compound nature. If we wish to represent that several similar compound radicals enter into the same molecule, we inclose the formula in a parenthesis, and as with atoms use the numerals thus, (NH4)2C03, Fe2(OH)6. In the foregoing table will be found the more important ele- ments arranged according to both quality and quantity of com- bining power. The elements at the top of the table are negative to all below them ; and those at the bottom are positive to all above. They are also divided into monad, dyad, triad, etc., some appearing in two or even three columns, because of their ohange of equivalence. In the second table will be found the more common atomic groups, with the names of the classes of compounds they form, arranged, as far as possible, in the same order as the elements. In regard to their electrical order, less certainty exists than with the elements. COMPOUND MOLECULES. loo. Compound Molecules Classified. — The system of nomenclature now in use for naming chemical compounds is based upon the composition and properties of the bodies in question ; and the name of a body is intended to express our idea of its chemical composition. Homogeneous bodies are sup- posed to be made up of a collection of similar molecules ; hence, a formula which represents the composition of a single molecule really represents the composition of the mass. In applying names to compounds, we apply the name to the inolecule as well as to the mass. Compound bodies may be divided into two classes : ist, those whose molecules are composed of two kinds of atoms or radicals, called binary compounds, and, 2d, those whose molecules are composed of three or more kinds of atoms or radicals, called COMPOUND MOLECULES. 9 [ ternary molecules. Examples: NaCI, KBr, MgCl,. and (NH^jCl are examples of binary molecules. KCIO3, K^SO,, CaCOa, (NHi)NOs, and Ba(N03)2, are examples of ternary mole- cules. Acids, Bases, and Salts. — -Torniry molecules are divided into acids, bases, and neutrals or salts. An acid is a substance which usually possesses a sour taste, corrodes the metals with the evolution of hydrogen and the formation of salts, changes blue vegetable colors to reds, and neutralizes the caustic properties of alkalies by forming silts with them. All acids contain hydrogen, which can be replaced by a metal. This hydrogen is united to the remaining portion of the molecule, either directly, as in binary acids, or by a linking atom, usually oxygen, as represented by the following graphic formulae : The replaceable hydrogen of an acid is called basic hydro- gen, and the number of such atoms determines the basicity of the acid. A dibasic acid, for example, is one containing two atoms of basic hydrogen, a tri-basic acid three, a tetra-basic acid four, and so on. When the linking atom of these ternary acids is oxygen, the name of ox-acids is applied to them. The term sulpho-acids is applied to those containing linking sul- phur. A base has properties which in many respects are opposed to and neutralize the effects of acids. They restore the vegetable blue colors reddened by acids, they neutralize the sour taste, and they react upon acids to form salts, with the elimination of one or more molecules of water. The strong bases have a caustic action upon the tissues, decomposing the fats, with which they form soaps. A base may be defined as a compound whose molecule is composed of a positive atom, or group of atoms, united by link- ing oxygen to hydrogen. The positive atom is, in most cases, metallic* As: — V r, vr -R — O— H „ —OH /O— H ^'OH js._u— M, iia_Q_pj^ ^^_0H, Bi— O— H Fe— OH \0-H, I \OH I /OH Fe— OH NH4-O— H. \OH, * This definition applies only to inorganic bases. 92 MEDICAL CHEMISTRY. In the last formula we have an example of a compound radical united to H by O. The inorganic bases are named hydroxides or hydrates. A salt molecule is composed of a positive radical united by linking oxygen to a negative radical. The radicals, in this case, as in acids and bases, may be either simple or compound. Thus : K— O— CI, K— O— NOj, Naj = Oj = CO, Ba= 02=SOj, (NH^)— O— NO3. It is evident, also, that a salt may be formed by treating an acid with a metal, which replaces the hydrogen of the acid with metallic atoms. I I Zn + H2 = O2 = SOj = Zn = Oj = SO^ + HH. I ^1 It may be regarded, then, as an acid whose replaceable hydro- gen atoms have been replaced by positive atoms or radicals. In a dibasic acid, like H — OXq/O it is possible to replace one H-0/^\0, of the atoms of hydrogen and leave the other undisturbed. We thus have, for example H^OXo/O which exhibits the prop- K— 0/*\0, erties, and answers to the definition of both a salt and an acid. It has acid properties by virtue of the replaceable hydrogen, and saline properties by virtue of the other chain in which the K has replaced H. Such a body is called an acid salt, while the salts first men- tioned, in which all the H atoms have been replaced by positive atoms, are called normal salts. Double salts are formed by replacing a part of the hydrogen of the acid by one positive radical, and a part by another. KNaSO^ from HHSOj, ^^ O— PO from H— O— P O NH,-0/ H— 0/ If a base or metallic oxide be treated with sufficient acid to neutralize it, a neutral salt is usually formed ; but if the base or oxide be much in excess of what the acid would require to expel all its hydrogen, a basic salt will in some cases be formed accord- ing to the following formula : — Pb<0-H Pb/°~^ =0 ^^ pb/O-Pb/0 -N=0, NOMENCLATURE. 93 /. e., if the base be used, the acid will take the place of a part of its replaceable hydrogen, and leave a part of it; or, a part of the excess of oxide will crowd into the molecule between the nega- tive radical and the positive. Such bodies are called basic or subsalts. The subsalts are seldom of definite chemical composition, often being mixtures of the oxide with the basic or even normal salt. Lead and'bismuth are two metals especially liable to form basic salts. r;=o <^0 ■' Bi-°/ PIj— O— I'b— 0-(C,H30) NOMENCLATURE. loi.— Naming of Chemical Compounds. — Rule. — Give the name of the positive radical first ; then the name of the leading negative atom or radical with its termination changed to id* or ide in binaries, and to ite or ate in ternaries : ite denoting the lower, and ate the higher equivalence of the negative atom. Na CI ^ Sodium Chlorid or Chloride, — liinary. Na NO2 = " Nitrite, — ternary. Na NO3 ^ " Nitrate, — " Ba CI2 ^= Barium Chlorid or Chloride, — binary. Ca Brj = Calcium Bromid or Bromide, — " Ca SO3 = Barium Sulphite, — ternary. Ba SO^ = " Sulphate, — " As will be seen on inspection, the equivalence of the nega- tive atom is indicated by the comparative amounts of oxygen which it holds. Compare BaSOj, and BaSOij also NaN02 and NaNOj. In compounds like the following — SnClj, SnCl,, CuClj, CujClj, HgClj, HgjClj, FeClj and Fe2Cl6 — where there are more * The final e, in the spelling of the names of the binary compounds, is recommended to be dropped by the rules of the American Association for the Advancement of Science. For these rules, see Appendix. The reasons for retaining the established spelling in this edition will be found in the Preface. 94 MEDICAL CHEMISTRY. than one equivalence of the positive atom, the endings ous and ic are used to distinguish them ; thus : — SnCIj = Stannous Chloride, dyad tin. SnCl^ = StannzV " tetrad tin. CuClj = Capn'c '' Cu.Cl^ — Cvprous " Hg.CJ, = Mercuious " HgCl, = Mercur?V " FeClj = Ferrous " dyad iron. Fe^Clj = Ferric " tetrad iron, When more than two equivalences are known, we employ the prefix per to denote an equivalence higher than that ex- pressed by ic or ate, and hypo to denote a lower than that expressed by ous or ite. They are prefixed alike to positive and negative. EXAMPLES. N,0 = Nitrous oxid or oxide. N,0, = Nitric " " N,0, = Na.,S.,03 = H,S03 = H^SOi = KCIO = HCIO2 = IICIO, = Nitric peroxid or tetroxid. Sodiuni Hyposulphite. Hydrogen Sulphite or Sulphurous acid, " Sulphate or Sulphuric acid. Potass. Hypochlorite. Hydrogen Chlorite or Chlorous acid. " Chlorate or Chloric acid. KCIO, = Potass. Perchlorate. Cl.,0 = Hypochlorous oxid or oxide. The class of bodies which we have called acids are more com- monly named in the following manner : — The negative atom, with the prefixes and suffixes usually at- tached to positive elements, is named first; this is followed by the word acid, thus : — HCl = Hydrochloric acid for Hydrogen Chloride. HBr = Hydrobromic " for " Bromide. HI = Hydroiodic " for " Iodide. HjS = Hydrosulphuric acid for " Sulphide. The binary compounds, above mentioned, are called hydr- acids to distinguish them from the oxacids or ternary acids; and in the naming of these acids the prefix hydro is used. NOMENCLATURE. 95 EXAMPLES OF OXACIDS. HCIO ^ Hydrogen Hypochlorite or Hypochlorous acid. HNO2 = " Nilrite " Nitrous HClOj = " Chlorate " Chloric HNO3 = " Nitrate " Nitric " H^SOs = " Sulphite " Sulphurous " H2SO2 = " Sulphate " Sulphuric " H^COj = " Carbonate " Carbonic " It will be seen that each of the above acids has a characteristic negative group of atoms; thus in sulphates we may always expect the group SO/'. In a sulphite we will always find the group SO3" ; in a nitrate NO/ ; in a chlorate CIO3', etc. 102. — Nomenclature Simplified. — The above rules of no- menclature may be applied much more easily by the student by reference to the table given on page 89. By the use of this table, the student can easily learn to name all the more common compounds. Let it be desired, for example, to name the following formula : Cu SO4. Cu is the symbol for copper. We next look among the compound radicals and find SO4 to be the characteristic -group of atoms found in all sul- phates. The name of the formula is, therefore, copper sul- phate. What is the formula of zinc carbonate ? We find zinc among the dyads, as also the group CO3, opposite the word carbonates. Both these radicals are dyad, and as a dyad is equivalent to a dyad, they will combine directly, and we shall have Zn CO3 as the desired formula. What is the formula of sodium sulphate ? The symbol of sodium is Na; it is monad, while SO^isa dyad. Two monads are equivalent to one dyad. Hence NajSOjis the formula of sodium sulphate. Let it be desired to know the formula of calcium phosphate. Here we wish to combine a triad and a dyad. To do so we must double the triad to get an even number of bonds ; we must take, then, three atoms of calcium to get six bonds. The formula will thus be Ca3(P04)2. What is the formula of ferric oxide ? In ferric iron two atoms always go together as a hexad. It will require three dyads to saturate the hexad, and we have Fe^Oj, or Fe^ (O-Hjs, or FeaCls. Stannous chloride will have the formula SnClz, while stannic chloride will be SnClj. Mercuric oxide will be HgO, but mercurous oxide will be HgjO. Cuprous chloride ^= Cu^Clj. Examples for Practice. — We introduce here a series of formulae for practice in nomenclature, with corresponding names in columns below. The numbers opposite the formulae will be found opposite the corresponding names below. 96 MEDICAL CHEMISTRY. I BaOjH^ 2 CaCjO, 3 BiCl, 4 NajCO, 5 MgSO; 6 Ke,(SO,l3 7 AgNO, 8 (NHJCI 9 HNO3 lO Hp;,Cl, II PbCrO, 12 KI '3 Kfi »4 AsjO, •s Cu^FeCyg i6 (NH,),S •7 ASjSj i8 NH^MgPOi '9 KHCO. 20 SbCls 21 BiONOs 22 Fe,(Fe,Cy„) 23 k(Cn;s 24 KjCrO, 25 Fe,{CrO,)3 26 AljiOHV 27 KCy 28 ZnO 29 SrCOg 30 Sr(N03), 31 BaClj 32 NH,N03 33 (NHJ,C03 34 KNaSi \ 35 NaHCOj 36 Ca3(P0,),. 37 CatPO.H,), 38 NaClO 39 BiPs 40 Oj 41 KCIO4 42 F\\0(C,Up,), 43 AgCl 44 AgBr 45 NaF 46 Nar 47 KBr 48 PbClj 49 fejClj 50 PtClj 51 AuClj 52 MnO.^ 53 K.MnO. 54 Ba(N03), 55 MnSOj 56 PbSO, 57 Cu(CjH30.,^„ 58 Ca(CjH.A), 59 Ca(OCl), 60 Fe,(C,H30,)e 61 NaiqHjO,) 62 Na^CjHjOj) 63 KjMnjOj 64 KjCrjO, 65 (NH,),C,0, 66 CaS03 67 CaCC.H^Oe) 68 Na,{QHA) 69 NajAsOj 70 NajAsOj. 1 Barium Hydroxide. 2 Calcium Oxylate. 3 Bismuth Chloride. 4 Sodium Carbonate. 5 Magnesium Sulphate. 6 Ferric Sulphate. 7 Silver Nitrate. 8 Ammonium Chloride. 9 Hydrogen Nitrate. (Nitric Acid.) 10 Mercurous Chloride. 11 Lead Chromate. 12 Potassium Iodide. 1 5 Potassium Oxide. 14 Arsenious Oxide. 1 5 Copper Ferrocyanide. 16 Ammonium Sulphide. 17 Arsenious Sulphide. 18 Ammon. Magnesium Phosphate. 19 Acid Potassium Car- bonate, orPotass. Bi- carbonate. 20 Antimonous Chloride. 21 Bismuth Oxy-nitrate. 22 Ferrous Ferricyanide. 23 Potassium Sulphocya- nate. 24 Potassium Chromate. 25 Ferric Chromate. 26 Aluminic Hydroxide, or Hydrate. 27 Potassium Cyanide. 28 Zinc Oxide. 29 .Strontium Carbonate. 30 Strontium Nitrate. 31 Barium Chloride. 32 Ammon. Nitrate. 33 Ammon. Carbonate. 34 Potassium Sod. Sul- phate. 35 Hydrogen Sodium Carbonate. 36 Tri-Calcium Phos- phate. 37 Calcium Hypophos- phite. 38 Sodium Hypochlorite. 39 Bismuth Oxide. 40 Oxygen. 4 1 Potassium Perchlorate 42 Basic Plumbic Acetate 43 Silver Chloride. 44 Silver Bromide. 45 Sodium Fluoride. 46 Sodium Iodide. 47 Potassium Bromide. 48 Lead Chloride. 49 Ferric Chloride. 50 Platinic Chloride. 51 Gold Chloride. 52 Maganic Oxide. 53 PotassiumManganate. 54 Barium Nitrate. 55 Manganese Sulphate. 56 Lead Sulphate. 57 Copper Acetate. 58 Calcium Acetate. 59 Calcium Hypochlo- rite. 60 Ferric Acetate. 61 Sodium Salicylate. 62 Sodium Benzoate. 63 Potassium Perman- ganate. 64 Acid Potassium Chro- mate. (Potassium Bichromate ) 65 Ammonium Oxalate. 66 Calcium Sulphite. 67 Calcium Tartrate. 68 Soiium Malate. 69 Sodium Arsenite. 70 Sodium Arsenate. NOMENCLATURE. 97 103. Irregularities in Nomenclature.— In many medical and pharmaceutical works, the old style of making the negative precede the positive, with the preposition of between them, is still used. In this case per is used instead of ic or ate, and proto instead of ite or ous. These irregularities are becoming obsolete. EXAMPLES. NEW NAME. OLD NAME. SnCl, = Stannous Chloride or Protochloride of tin. SnCI^ = Stannic " or Perchloride of tin. Ke,Cl, = Ferric " or Perchloride of iron. Fe,(SOj3 Fe,03 = " Sulphate = " Oxide = Mercurous Iodide or Persulphate of iron. or Per- or Sesquioxide of iron. or Protiodide of mercury. Hsr.CI., = " Chlorid( 2 or Protochloride, mild chloride, or calo mel. HgCl, = Mercuric chloride or Bichloride, corrosive sublimate. HgO Hg,0 = Mercuric oxide = Mercurous oxide or Red oxide of mercury, or Black oxide of " Protoxide of The proto-salts of iron are the ferrous salts, while the per- salts are the ferric salts. The names of the oxides of the alkaline metals, the earths, and alkaline earths are sometimes named as follows : — AljOj Alumina. . CaO Lime. MgO Magnesia. KjO Fotassa or Potash BaO Baryta. Na^O Soda. SrO Strontia. Some writers name those oxides of the non-metallic elements which dissolve in water, to form acids, as though they were formed from the acids by abstracting one or more molecules of water. Thus SOj is named Sulphurous Anhydride. CO, " " Carbonic " NjOj " " Nitrous N.P5 " " Nitric '■ P2O5 " " Phosphoric " For, SO, -f H.p = HjSOj = Sulphurous Acid. CO, +11,0 =H,C03 = Carbonic N2O5 -f- H,N = 2HNO3 = Nitric P2O5 -I- 3H,0 = 2H3POi = Phosphoric " SO,, 4- HjO = II, SO4 = Sulphuric " gS MEDICAL CHEMISTRY. It is a common custom with some authors to use the numerals di, tri or ter, tetra and penta, to indicate the number of atom? of the element to whose name the numeral is prefixed. NEW NAME. OLD NAME. Thus : — FeSj Ferric Bisulphide or Bisulphide of Iron. FejS Diferrous Sulphide or Sulphide of Iron. FcjSj Ferric Sulphide or Sesquisulphide of Iron. FeS Ferrous Sulphide or Protosulphide of Iron. COj Carbon Dioxide or Carbonic Acid. PClg Phosphorus Trichloride, PCI5 " Pentachloride, HgCl2 Mercuric Dichloride or Bichloride of Mercury. A few compounds are known by names which do not express their composition. Thus : — H3N Ammonia. CN Cyanogen (symbol Cy). HjSb Antimoniuretted Hydrogen or Siibin. HjAs Arseniuretted " or Arsin. HjS Sulphuretted " or Hydrosulphuric Acid. HjP Phosphuretted " or Phosphin. H4C Light Carburetted " or Marsh Gas. H^C2 Heavy Carburetted " or defiant Gas. A glossary of obsolete and popular names, and those of some chemical compounds only occasionally met with, will be found in the Appendix. 104. Chemical Reactions and Equations. — All material bodies, under certain conditions, may undergo marked changes in properties. As the physical properties of bodies depend upon the properties of their molecules, any great change in these properties must depend upon a corresponding change in the molecules. In a homogeneous mass of matter, all molecules are alike ; and any chemical change which we are able to produce in one molecule of such a mass, may, with certainty, be produced in all. Hence, by representing the changes which take place between two dissimilar molecules, we do, in reality, represent the changes taking place between the masses of which these molecules form a part. It is upon this principle that we repre- sent chemical changes to the eye. When two substances, on being brought together, act upon each other, the mutual action between them is called a reaction. A body which is added to another to cause such a change, is called a reagent. When a jet of coal gas is burned in the air, CHEMICAL REACTIONS AND EQUATIONS. 99 the reagents are the gas and the oxygen of the air. Tiie results of the reaction are light and heat. The products of the reac- tion, are the watery vapor and carbon dioxide which are pro- duced. The factors entering into the reaction, are oxygen and the compounds which compose the gas. While all material molecules are more or less liable to under- go chemical change by the action of external agencies, some do so very readily, while others resist such change with con- siderable force. Chemical reactions are favored by anything that lessens cohesion, or favors the free movement of the mole- cules ; as solution, pulverization, trituration, heat, light, and electricity. Reaction between solids is always slow, and, in many cases, entirely wanting. If the solids are brought together in solution, the reaction takes place with readiness : if volatilized, still more readily. Reactions between gases usually take place almost in- stantaneously throughout the mass, and in many cases, with an explosion. Heat usually favors chemical action, and cold retards it. Light favors many kinds of chemical change, but does not affect all. Reactions, in the laboratory, are generally conducted in solutions. When the bodies are soluble in water, that liquid is generally selected ; if not, some other solvent, such as ether, alcohol, chloroform, etc. , may be employed. When two or more substances are brought together in solution, the action that will take place depends largely upon the follow- ing conditions, first formulated by Berthelet, and usually known as the Laws of Berthelet: — 1st. When two or more substances are brought together in solution if by any rearrangement of the atoms a product can be formed which is insoluble in the liquid present, that substance will form and separate as a precipitate. 2d. When two substances are brought together in solution, if a gaseous body, or one volatile at the temperature of the experiment, can form, it will form and escape as a gas or vapor. Illustration. BaClj -|- Na^SO^ ^? By a rearrangement of these atoms, according to the principles stated in preceding articles, there can only form BaS04 and aNaCl. The latter of these is soluble in water, while the former is not; hence, BaSO, would always separate from this mixture. Zn -|- 2HCI = ZnClj -|- Hj. Here, by changing the places of the two positives, hydrogen is set free, and escapes. The above laws apply to insoluble or volatile substances only. lOO MEDICAL CHEMISTRY. When two acids in solution are made to act upon one base, or two bases upon one acid, to produce soltible non-volatile sub- stances, the base in the first instance divides itself between the two acids, or in the second instance the acid is divided between the two bases. That is, if a solution of sodium hydroxide be treated with an excess of nitric and hydrochloric acids, both sodium nitrate and chloride are produced ; or if sulphuric acid be treated with a mixture of sodium and potassium hydroxides, more than sufficient to saturate the acid, both sulphates are pro- duced. The quantities of each salt produced will depend upon the relative quantities of the two acids or two bases present, and the relative affinities between the acids and bases. In dilute solutions of the above compounds, nitric and hydro- chloric acids were found to be the strongest of the mineral acids, while hydrobroniic, hydriodic, sulphuric, phosphoric, oxalic, and acetic follow in the order named. The avidity of nitric and hydrochloric acids for sodium was found to be twice that of sul- phuric, or, when sodium sulphate is treated with excess of nitric acid, the following reaction takes place : — aNa^SOj + 4HNO3 = NajSOj + 2NaN03 + H^SO^ + ■2HNO3. As matter is indestructible, it follows that there can be neither loss nor gain in the weight of the matter taking part in a reac- tion. The sum of the weights of the factors entering into a reaction must, therefore, be equal to the sum of the weights of the products coming from it. Hence, if we place the sum of the lormulse of the factors equal, to the sum of the formulae of the products of any reaction, it must alvyays form a true equation. In writing out representations of chemical reactions, the student should remember the following rules: — ist. Positives combine with negatives and not with posi- tives. 2d. Every member of the equation must represent a whole molecule, or a number of molecules. 3d. The equivalences of the atoms and radicals must all be saturated according to the rules laid down in Art. 95. 4th. An acid and a base cannot exist in the same solution. They are incompatibles, and neutralize each other. 5th. The strongest acids generally select the strongest bases, except in cases where this is modified by Berthelet's laws. Com- pound radicals, as a rule, remain as such in the products. To write chemical equations, place the formulae of the factors, connected by a plus sign, equal to the formulae of the CHEMICAL REACTIONS AND EQUATIONS. lOl products, also connected by a plus sign. Now take such a num- ber of molecules as factors that only whole molecules can be produced in the products. i EXAMPLES. + - +- Ag NO3 + Na CI = (?) Silver Sodium Nitrate. Chloride. We first determine which are positive and which are negative radicals. The metals are positive (Art. 94), and the non-metallic radicals are negative, as indicated by signs above the symbols. We next cause the positive radicals to exchange places, whence we have Ag CI and Na NO3. On referring to the table of equivalences (Art.. 99), we find all these radi- cals to be monad, and therefore chemical equivalents. The completed equation will, therefore, be: — Ag NO3 -f Na CI = Ag CI -I- Na NO3. Silver Sodium Silver Sodium Nitrate. Chloride. Chloride. Nitrate. EXAMPLES FOR PRACTICE. Complete the following : — 1. 2Ag(N03) + H5,S = ? 2. Pb (N03)j -I- H,S = 3. H,(SOJ-FCaO,H,= 4. KI + Ag NO3 = 5. Fe CI, -f- 2KC)H = 6. Fej Clj -f- 6KOH = 7. Ni (NO3), -h Na,S = 8. Mg SOj + 2(NH,) OH = 9. Ba CI, + Na, SO4 = 10. Bi CI3 + H,0 = Bi OCI + ? 11. Pb (CjHjO,), -f H, SO^ = 12. Ba CI, -I- (NHJ, CrO^ = 13. Na, CO3 -f 2HCI = 14. Cu SO^ -I- NaOH = 15. Hg, (NO3I, -I- NaCl = 16. Mg SOi -f H NajPOl -|- NH^OH = 105. Stochiometry. — Chemical symbols represent definite weights, or atomic weights. Chemical formula, therefore, enable us to calculate the percentage of any ingredient in the com- pounds they represent ; or, from chemical equations, we may calculate the weight of any substance required by any given process, or the exact amounts evolved by it. These calculations are all based upon the atomic weights. Molecular weights are derived from the atomic weights. 102 MEDICAL CHEMISTRY. The molecular weight of calcium carlMnate, Ca CO3, is (C = 12) + (O3 = 48) + (Ca = 40) = 100. (See Table, Art. 87.) On inspection, we see that ^Yj of 'he whole quantity is calcium, j^j^^ carbon, a"d fjV oxygen. Let it be desired to calculate the qumtity of hydrogen in one'part of water ; formula HjO. (Hj = 2) + (O = 16) = 18 = jV- Hydrogen, Jf = Oxygen. Stated in the form of a proportion, this would be 18:2:: I : ^^ = ^. In this proportion, the fourth term must bear the same relation to the third that the second does to the first. What is the per cent, of calcium and oxygen in CaCOj ? The first problem would be stated as follows : — CaCOj : Ca : : I : X 100 : 40 : : i ': x = /j"iy ^= -4° Of 4° P^f cent. In other words, calcium carbonate contains 40 per cent, of calcium. The same calculation may be made for oxygen, as follows : — CaCO, : O, : : I . x 100 : 48 : : I x ^ .48 or 48 per cent. If, instead of one part, we desire the amount in ten parts, we substitute 10 for one in the third term for the equation, thus : 100 : 48 : : 10 : 4.8 parts. The fourth term of such an equation will always be of the same denomi- nation as the third. From the above, we easily deduce the following rule for the statement of such problems : As the formula of the sub- stance given is to the formula of the substance required, so is the weight of the substance given to x, the weight of the substance required. Reduce the formulae to their numerical equivalents, and find the value of x. When three terms of an equation are given, the fourth may be found by multiplying the two means (second and third terms), and dividing the product by the given extreme. In calculating the per cent, of any ingredient, by the above rule, the weight given is understood to be 100, i. e., per cent, is parts per hundred. Calculations based upon a reaction may be illustrated as follows : — Problem. — How much sulphate of zinc can be prepared from 10 grammes of zinc ? Reaction.— Zn + H^SO^ = ZnSO^ + Hj Statement. — Zn : ZnSO, : : 10 : x Numerical statement. — 65 : (65 -|- 32 + 64 = 161) : 10 : x Solution. — 161 X 10 = 1610 1610 -:- 65 = 24.8, Ans. in grammes. CHEMICAL REACTIONS AND EQUATIONS. I03 Problem. — How much NaNOg will be required to make one pound of HNO3 ? Equation.— NaNOj + H^SO^ = NaH SO, + II NO3 The only terms of this equation concerned in the problem are Na NO3 and HNO3 ; the latter being the substance given. Statement. — HNO3 : NaNO, : : i : x pounds. Numerical Statement.— 63 : 85 : : i . x Solution.— I X 85 = 85 85 -f- 63 == 1.3s pounds of Na NO3. PART III. INORGANIC CHEMISTRY. io6. Classification of the Elements. — For convenience of study, some system of classification of the elements is neces- sary. Many systems of classification have been proposed, but all are open to criticism ; yet, we may adopt one of these with the understanding that the classification is largely an arbitrary one, and serves merely for convenience. Berzelius was the first to divide the elements into two great classes, to which he gave tlie names metals and metalloids. The metals are those elements which possess more or less lustre and opacity, readily conduct heat and electricity, and are electro-positive in com- binations. The non-metals, or metalloids, are such as are gaseous ; or, if solid, have no lustre, ductility or malleability, are poor con- ductors of heat and electricity, and are electro-negative in combinations. This division, while it serves a general purpose, is not capable of exact application ; for there are a number of the elements which are' positive in one combination and negative in an- other. Iodine and arsenic, which most chemists regard as metal- loids, have a decided lustre, and the latter forms alloys by fusion with the metals; indeed, there is no line of demarkation, be- tween these two classes, which can be regarded as fixed. Some classification is necessary, which is not based upon the physical properties alone, but upon their chemical properties; a classification which brings together those elements which have similar chemical properties, and similar compounds with other elements; thus enabling the student to better associate the facts of each in his mind. There are two important chemical characters upon which most attempts at classification of the elements into groups have been based ; viz. : equivalence, and electrical polarity of the atoms. By a consideration of both of these properties, the elements may be grouped so as to bring similar elements together. 104 INORGANIC CHEMISTRY. I05 The behavior of the oxides of the elements with water, may be taken as an index of their polarity. Electro-negatives dis- solve in water and form acids, while electro-positives form bases, and some again play a neutral or double role. The most successful attempt to find a natural system of classi- fication of the elements is the one first proposed by Newlands and afterward developed by Mendelejeff, and is the only natural one in use. It is based upon the atomic weights and is sometimes known as the periodic law. If a list of the elements be made, arranging them in the order of their atomic weights, from the lowest to the highest, the first seven (after hydrogen) will be found to be representative of seven groups of similar elements. (See Table, page io6.) Let each of these seven elements head a column, and arrange the rest under them in the order of their atomic weights, in lines from left to right. We notice that those elements resembling one another in their chemical properties will be found together in the vertical columns. It will be noticed that the metals are near the bottom of the table, while the non- metals are at the top. In Mendelejeff's original table there were seven vertical columns which are called the seven groups. There are twelve lateral rows which are called series, or small periods. If these lateral rows or series be numbered, it will be noticed that the members of the alternate numbered series of a given period resemble one another more nearly than the adjoining numbered ones. Thus, in the first group ; Li ^ 7, K = 39, Rb ^85, Cs = 133, resemble one another more nearly than Na, Cu, Ag, Au. It will be noticed that hydrogen is arranged in the first period as the only one of that period. The table is imperfect in some cases, but in the main it brings together ele- ments which form well-defined natural groups. As an example of such a group, take Nos. 2, 3, 5 and 7 of Group VII. With the increase of atomic weight they increase in specific gravity and consistency. Of the group, fluorine is strongly electro-nega- tive, while chlorine, bromine and iodine grow more positive as the atomic weight increases. They all form acid hydrides con- taining one atom of basic hydrogen. They all possess a peculiar and somewhat similar pungent odor. They all have the leading equivalence of one, while the three last have a higher equiva- lence in certain oxygen compounds. While there are certain striking groups brought together by this arrangement, there are some irregularities. Thus, there is no series in which hydrogen finds a place. In making this element a period by itself, the last four members of the second io6 MEDICAL CHEMISTRY. > 1' Silo gS 11 • • A IIS «s li • • 1 o o _E bo On - fl i^ pll i2^- • • 11:^ o (§112 • 5 II- ' ■ ^ m "^ — o r* ON i CO II o II II ■ ■ O fc u S M 1— 1 N CTv ITi ro t^ M > c„ II II *2. i • ^ o o-iBO VO cn a\ M * gsipj o o II =" U II o eS • II 01 II 1=> ^ in "S ro ^^ N o •* ■ II II "^ in s; ii 1 CO II o i A- II < ^ ^ M II II n ■ :z; > ;z; 3 H oo M 00 t^ N r^ o > N • ^ II o ON i ? • II « II Ol II ^ II eg ii . o V jB u H N O H r^ o ro VO 'J- (N r^ M ^ „ o II < a\ M fO N o i II o Ov 00 II II a ii J3 II H ■ m C/3 > 1-1 tx 1 ■* ■LTi M Q N VO II II II N at 00 II u i s i : 1 h-t • fO 00 r^ II II w S II II s II U o ^— s On II iz; .J? II i M II X i 13 W (U u ' -SHIHHS "1 « , n ^ in ^o t^ 00 o\ o M N INORGANIC CHEMISTRY. lo; period, C, N, O, and F, are made even-numbered, which re- moves them from the others of the same group which they most nearly resemble. Even with these imperfections, the table is an attempt to classify the elements upon some natural basis, and has enabled its author to predict the discovery of at least three new elements, viz. : gallium, scandium, and germanium, and describe their properties, years before they were discovered. This he was led to do from the vacant places in the table. As hydrogen stands alone in the table, we shall study it first. It will be convenient to retain tlie classification into metals and non-metals. The non-metals will be studied first, be- ginning with those of the seventh group, and taking the second series with the odd-numbered series below the second. The order in which the elements will be studied is the following, with the omission of those whose symbols are in italics, as being of little interest to the medical student : — NON-METALLIC ELEMENTS OR ODD SERIES. Seventh Group, . . Sixth " Fifth " Fourth " First Second Third Fourth Fifth Sixth Seventh Eighth •{ . F. CI. Br. I. . O. S. Se. Te. N. P. As. Sb. Bi. C. Si. Ge. Sn.* Pb.* ETALS. U. Na. K. Rb. Cs. Cu. Ag. Au. Be. Ca. Sr. Ba. Mg. Zn. Cd. Hs. B-f St. yi. La. yb. AI. Ga. In. E. Tl. Ti. Zr. Ce. Th. V. Nb. Di. Ta. Cr. Mo. W. U. Mn. Fe. Co. Ni. Ru. Pd. * These elements, although classed in the series with non-metals, are gen- erally regarded as metals, f Non-metal. I08 MEDICAL CHEMISTRY. GROUP I. HYDROGEN. Symbol, H. Atomic Weight, i. Molecular Weight, i. Density, i. Weight of one liter ^ i crith =: .o8g6 grm. Equivalence, one. I gr. == 46.7 cu. in. at 60° F. and 30 in. barometer. I gram = 1 1. 1 6 liters at 0° C. and 760 mm. barometric pressure. 107. Occurrence. — It was discovered in 1766 by Caven- dish. Hydrogen occurs in a free state in the gases from volca- noes, fumeroles of Iceland and Tuscany, and in the atmosphere of the sun; in combination, it exists in water, and in most organic substances of both animal and vegetable origin. It is a necessary constituent of all acids, bases and ammoniacal com- pounds. 108. Preparation. — Hydrogen maybe prepared: — First. — By the decomposition of water, by a strong electric current, which splits the water into hydrogen and oxygen ; the former appearing at the negative and the latter at the positive pole. Second. — By decomposing water by certain metals. When sodium or potassium is used, the decomposition takes place in the cold ; but with iron and some other metals at a red heat. I I I ri I Na, + 2H2 O = 2NaH0 -|- Hj 3Fej + 8H,0 = z?tfi^ -f 8H, I I Third. — By the decomposition of the mineral acids with some metal, as zinc, iron, or magnesium. In this case, the metal takes the place of hydrogen, which is crowded out of the acid mole- cule. I 1 I I Zn + HjSO^ = ZnSO^ + Hj 65 grams of zinc give 2 grams = 22.32 litres of hydrogen. HYDROGEN. 109 Water is added to dissolve the zinc sulphate formed, and to prevent it from crystallizing on the surface of the zinc. Chemi- cally pure zinc, however, will not dissolve in very dilute acid, unless it be made one pole of a galvanic couple. This method is the one usually employed for the preparation of hydrogen in the laboratory. The apparatus is shown in Fig. 39. The gas prepared from commercial zinc and acid is not pure, how- ever, as it contains other gases derived from impurities in the ma- terials used. Pure hydrogen in small quantities, may be prepared by the first method, or by decomposing water with an alloy of sodium and mercury — sodium amalgam. log. Properties. — When pure, at ordinary temperatures Fig. 39. PREPARATION OF HYDROGEN. and pressures, hydrogen is a colorless, transparent, odorless, tasteless gas. It is 14^ times lighter than air, being the lightest gas known. ' One liter of it at 0° C. and 760 mm. pressure, weighs .0896 grm. = the crith. It is almost insoluble in alcohol, and at a temperature of — 140° C. and under a pressure of 650 atmos- pheres, it has been condensed to a steel-blue liquid. It is the best conductor of electricity and heat among the gases. It is very diffusible, and a vessel to contain it, must be made of glass or some very compact material. Certain metals absorb large quantities of it. Palladium will absorb 900 times its volume of MEDICAL CHEMISTRY. Fig. 40. the gas : spongy platinum, sodium, potassium and iron also absorb considerable quantities of it. Tliis action of the metals is called occlusion. During the condensation of the gas in the pores of the metal, the latter is heated to a considerable degree. A jet of hydrogen may be ignited by directing it upon a ball of finely divided platinum, or a ball of asbestos, which has been dipped into a solution of platinum chloride, and heated in the flame of a lamp, Under ordinary conditions, hydrogen has little tendency to unite with the other elements, chlorine being the only one with which it combines directly, and then only under the influence of light. At higher temperatures it unites with oxygen, and is, therefore, readily combustible in the air, burning with a bluish and very hot flame. The product of the combustion is watery vapor, as may be shown by inverting a jar over the burning jet, and collecting the drops of water. A given weight of hydrogen produces more heat in burning than any other known combustible. It will not maintain animal respiration, but is not poisonous. A lighted candle is extin- guished on being thrust into it, while the gas burns at the open mouth of the jar. On withdrawing the candle it relights. (See Fig. 40). If hydrogen and oxygen be mixed together and a lighted taper applied to them, an explosion takes place. The hydrogen combines with one- half its volume of oxygen. In other words, when these gases combine they do so only in the one proportion. This law holds good with all chemical com- binations, and is known as the law of definite proportions. Hydrogen has so great a tendency to unite with oxygen, at high temperatures, that it will take it from many metallic oxides, and leave the metal in the free state. This process is called reduction or deoxidation. It is by this process that the reduced iron or iron by hydrogen of pharmacy is produced. Hydrogen will unite quite readily with some elements which it ordinarily does not affect, if they be put into the flask where the hydrogen is generating. Arsenic and antimony com- pounds, for example, are split up, and these elements unite with the hydrogen. Many oxides are reduced, and chlorine is HYDROGEN. Ill removed from some chlorides, under these circumstances. The greater energy of the hydrogen, in these cases, is explained by the supposition that at the moment of liberation of the hydrogen atoms, and before they have combined into molecules, they are ready to take up with any atom with which they may come in contact. They are stronger in their affinities, before combining with a neighboring hydrogen atom, by just the force it will take to decompose the hydrogen molecule when once formed. This condition of an element is known as the nascent state (from nascere, to be born). When any chemical action takes place between molecules, there is a considerable expenditure of force required to break up the combinations already formed, before new ones can be formed ; and when these combinations do not exist, the new combinations take place with ease. Hydrogen is one of the constituents of the gases of the stomach and intes- tines, and is frequently found m the gases exhaled from the lungs. Its physiological properties, if any, are slight. In its chemical properties, hydrogen resembles the metals more than the metalloids, usually playing the positive role, and forming salts in which it occupies the place of metallic atoms in similar compounds, and is easily substituted for or displaced by them. On this ground, the acids may be regarded as salts of hydrogen. no. Uses. — The uses of hydrogen are limited. Owing to its lightness, it is sometimes used to fill balloons. The ascen- sional power, or the lifting power, of one litre of hydrogen is 1.2036 grms., and is found by deducting its weight, .0896 grm., from the weight of one litre of air, 1.2932 grammes. The lift- ing power of one cubic foot is about 525 grains, or one ounce and 55 grains. Hydrogen is also used with oxygen in the oxy- hydrogen blowpipe. In the laboratory, it is used as a reducing agent. NON-METALLIC ELEMENTS OF GROUP VII. (Chlorine Group, or Halogens.) SYMBOL. ATOMIC WEIGHT. STATE. Fluorine, F. ig gas. Chlorine, CI. 3S.5 gas. Bromine, Br. 80 liquid. Iodine, I. 127 solid. Ill, The elements of this group are electro -negative, fluorine being most negative, and the iodine least so. They have a 112 MEDICAL CHEMISTRY. characteristic, pungent odor, and act as disinfectants and bleach- ing agents. They enter into direct union with many of the metals to form binary compounds. They form compounds with hydro- gen, having well marked acid properties. They have little affinity for oxygen, but form several oxacids and salts, all of which are rather unstable. They form the following compounds : — TTp _^ __ ___ Hci. C1.0 op, Cip. HCIO HCIO, HCIO, HCIO,. HBr. _ _■ - HBrO - HBrOs HBrO,. HI. — iPa I2O3 HIO HlOj HIO3 HIO^. FLUORINE. (fluorin.) F — 19. D. = ig. Sp. Gr. 1.3. Equivalence I. 112. Source. — The sources of fluorine compounds are native fluor spar — calcium fluoride — and cryolite — a sodium and alum- inium fluoride. Preparation. — By decomposing pure, dry hydrofluoric acid in a U tube composed of platinum, by means of a strong electric current from twenty or more Bunsen cells. The hydrofluoric acid must be prepared with care, and must be free from water. As hydrofluoric acid is a non-conductor, a small quantity of po- tassium hydrogen fluoride is dissolved in it to increase its conduc- tivity. The apparatus is cooled to — 23° C. during the process. The fluorine is liberated at the positive pole as a colorless, trans- parent, pungent gas, having the properties of chlorine, but much more marked. Silicon, boron, arsenic, antimony, sulphur, and iodine take fire in it. It instantly decomposes cold water, form- ing hydrogen fluoride (HF.), and sets free the oxygen as ozone. Most organic bodies are attacked by it, the hydrogen being re- moved, but the carbon remaining unattacked. It combines with hydrogen with an explosion, even in the dark. Alcohol, ether, benzene, turpentine, and petroleum take fire on being brought in contact with it. It attacks the metals slowly, in bulk, but rapidly when in powder. Owing to the action of fluorine on the metals and all glass articles, it can only be prepared in vessels of plati- num or fluor spar. 113; Hydrogen Fluoride. — Hydrofluoric Acid (HF).^- This acid is obtained by the action of sulphuric acid up'on pow- dered fluor spar, with the aid of a gentle heat. CaFj -f H,SO, = CaSO^ + 2HF. CHLORINE. 113 The operation is usually conducted in a lead or platinum vessel, as the acid attacks glass and most metals. The acid is a colorless, transparent gas, with a pungent odor, very irritating to the skin and mucous membranes. It is readily soluble in water, forming a colorless, highly acid and corrosive liquid, with a pun- gent odor. Care must be taken, in using it, not to allow it to come in contact with the skin, as it produces a painful ulcer, which heals with difficulty, and also constitutional symptoms of considerable severity. The boiling point of the liquid is between 15" and 20° C. (59 and 68° F.), and it has a specific gravity of 1.060. The most characteristic property of hydrofluoric acid, is its power of dis- solving glass by removing its silicon. This property is utilized for etching glass. The article to be etched is first coated with a thin layer of melted wax or paraffin, and the characters are then scratched through the wax with a steel point, so as to expose the glass where the etching is to take place. If the liquid is to be used, a wall of wax is built up around the characters and the liquid is poured into the inclosure. The characters thus etched are transparent. It is more common to invert the glass, wax downward, upon a leaden dish containing the fluor spar and sul- phuric acid, and expose it to the fumes until the etching is as deep as desired. The etchings in this case are opaque, present- ing the appearance of ground glass, and more easily seen. Fluorine forms no oxides. CHLORINE. (CHLORIN.) CI-35.5. D. = 35.5. Sp. Gr. = 2.47. Equivalence I, III, V or VII. 114. Occurrence. — Chlorine always occurs in combination in nature. The chlorides of sodium, potassium, magnesium and calcium occur in salt springs. Usual source, sodium chloride or common salt. Preparation.— By the action of warm sulphuric acid upon sodium chloride, in the presence of manganic oxide, contained in a flask as represented in Fig. 41. zHjSOi -f MnO, + 2NaCl = Na^SO^ + MnSOj + 2HjO + Clj. Or, by acting upon manganic oxide with hydrochloric acid. 4HCI + MnO^ = MnCIj -f- aH^O + O.,. jj. MEDICAL CHEMISTRY. For a slow continual evolution of chlorine, as for disinfecting pu^etrois^nedchl^^^^^^^^^^^^^ calcium hypochlorite >« decomposed Dy^ evolution, we "'prooertref-Physical.-At ordinary temperatures chlorine is r grSSh yellow^ungent, suffocating gas^ ^^ ^ ^S" Fig, 41., trasat 10° C. (■;o° F.). The solution, aqua chlori, U. S. P., fs made at this temperature, and contains 0.4 per cent by weight of^he gas It is a greenish-yellow liquid, possessing the proper- des of the ga , but slowly changing in the light into hydro- chloric acid^ It should bleach but not redden litmus paper Ch°o hie water should be kept in a dark place, as otherwise decomposition takes place. The CI unites with the H of the water forming HCl, and setting O free. Under a pressure of four atmoTphfres, a ordinary temperatures, or a temperature of 40° C (-40° F ), the gas is condensed to a dark yellow liquid. CHLORINE. 115 Chemical Properties. — The affinities of chlorine are very strong and extensive. It is characterized by its strong tendency to combine with hydrogen and the metals, with which it forms chlorides. It combines directly with many elements, as finely divided copper, antimony or arsenic, with the evolution of light and heat. Its attraction for hydrogen is so strong that a mixture of these gases combine with an explosion, when exposed to direct sunlight, the light of burning magnesium, or the electric light. It burns rapidly in an atmosphere of hydrogen, forming gaseous hydrochloric acid, HCl. It is capable of existing in two allo- tropic states ; the one active and the other passive. The passive or inactive form is the one obtained when the gas is prepared in the dark. When prepared in daylight it is very active in its pro- perties. When the same element is capable of existing in two or more forms, having different properties, these forms are called allotropic conditions; the property is called allotropism. One of the most marked chemical properties of chlorine, is its affinity for hydrogen. So great is this affinity, that many organic compounds are spontaneously decomposed by it ; the chlorine combining with the hydrogen of the compound and setting the carbon free. A paper wet with turpentine and plunged into a jar of chlorine, takes fire and deposits the carbon as a dense black cloud, while fumes of HCl fill the jar. The well known bleaching and disinfecting powers of chlorine, are due to its affinity for hydrogen. Most vegetable colors, when moist, are readily discharged by chlorine. The chlorine combines with the hydrogen of the water and sets free the oxygen, which, in the nascent condition, is a powerful oxidizer, and decomposes the coloring agent, or organized germ, as the case may be. In some cases the chlorine acts directly upon the organic matters, uniting with a portion of their hydrogen to form HCl, and a portion of it entering the molecule to take the place of the hydrogen re- moved. Thus, with marsh gas, hydrochloric acid and methyl chloride are produced. CH4 -f CI2 = CH3CI + HCl. 115. Hydrogen Chloride. -^ Hydrochloric Acid. — Acidum Muriaticum — Acidum Hydrochloricum, U.S.P. — (HCl). Hydrochloric acid occurs very sparingly in nature. It is found in volcanic gases and in the gastric juice of mammals. Preparation. — The acid is usually prepared from sodium chloride or common salt, by treatment with commercial sulph- uric acid, by the aid of a gentle heat. The process is sometimes conducted as a special process, but a large quantity of the acid is prepared, as a side product, in the i[6 MEDICAL CHEMISTRY. preparation of sodium carbonate by Leblanc's process, The first step in this process is to treat the salt with sulphuric acid, and thus convert it into sodium sulphate. The acid set free by this process, is collected and sold as impure hydrochloric acid. HjSO^ + 2NaCl = 2HCI -f- Na^SOj. The acid may be prepared in small quantity by the direct union of equal volumes of chlorine and hydrogen, under the in- fluence of sunlight or the electric spark. (See Art. 90.) Properties. — Hydrochloric acid is a colorless, transparent gas, having a pungent, penetrating odor, a sharp, sour taste, Fig. 42. PItEPAKATION OF HCl an acid reaction; and produces great irritation of any tissue with which it comes in contact. It is irrespirable and extin- guishes a flame. It is very soluble in water. One volume of this liquid dissolves 450 volumes of the gas at 15° C. (59° F.). This solution forms the ordinary muriatic acid. The specific gravity of the solution is 1.21, and contains about 32 percent, of HCl. The sp. gr. of the gas (air = i) is 1.264; the density (hydrogen ^ i) is 18.25. Under a pressure of 40 atmospheres, at 10° C. (50° F.), it condenses into a colorless, limpid liquid. CHLORINE. I I 7 having a sp. gr. of 1.27. A strong solution in water fumes strongly in the air, giving off a part of the gas. On being heated it gives off its acid rapidly. The commercial muriatic acid is yellow in color, due to the presence of ferric chloride. It also contains other impurities, and is used only for manufac- turing purposes. The composition of the acid may be jJetermined by means of the apparatus shown in Fig. 45, p. 129. The apparatus is filled with the strongest commer- cial acid mixed with ten volumes of a saturated solution of common salt (Na- Cl). The binding posts are connected wiih a battery of two Bunsen cups. The chlorine separates at the positive pole and the hydrogen at the negative pole. The volumes of the two gases are equal. By the use of the apparatus shown in Fig. 46, we may arrive at the same result by synthesis. We introduce through the stopcock at the top of the apparatus equal volumes of hydrogen and chlorine. By opening the stopcock below, draw off the mercury until the height of the column is the same in both limbs. Attach the wires to a battery and induction coil arranged as in Fig. 29. On passing the current a series of sparks is sent through the mixed gases, causing them to combine with an explosion. No contraction is observed. No excess of either gas is left, but a new gas has taken their place, viz. : hydrochloric acid. (See Art. 90.) Acidum Hydrochloricum, U. S. P., a colorless, fuming liquid having a pungent odor and an intensely acid taste. Its sp. gr. is 1. 163 at 15° C. (59° F.), and it contains 31.9 per cent, of absolute hydrochloric acid. Acidum Hydrochloricum Dilutum, U. S. P., is made by diluting the stronger acid with water. (Strong acid 3 parts, dis- tilled water 13 parts). The sp. gr. ^ 1.050, and contains 10 per cent, of HCl. Pure hydrochloric acid should be colorless, and when diluted with distilled water, should give no precipitate with HjS, NHjOH in excess, or BaCl,, and should not dissolve gold leaf. (Absence of HNO3. ) Tests — (i) Heated with MnOj it gives off CI. (2) Added to AgNOs it gives a curdy, white ppt. soluble in ammonia water, but insoluble in nitric acid. AgNOj + HCl = AgCl -I- HNO,. (3) Added to mercurous nitrate it gives a white ppt. which is blackened by ammonia water. Hg^lNOs), + 2HCI = Hg, CI, + 2HNO3. Acidum Nitrohydrochloricum, Nitro-Muriatic Acid, U. S. P. (Aqua Regia). This is made by mixing 180 c.c. of nitric acid with 820 c.c. of hydrochloric acid in a capacious glass vessel, and when effervescence has ceased, pouring the pro- duct in amber-colored glass-stoppered bottles. Il8 MEDICAL CHEMISTRY. The two acids act chemically upon each other, forming chloro- nitric or chloronitrous gas and chlorine. These equations ex- press the reaction that probably occurs. HNO3 + 3HCI = NOCI,? + 2HjO -f CI. HNO3 + 3HCI = NOCl + 2H2O+ Clj. This acid has the power of dissolving gold, "the king" of metals, and hence its name aqua regia. It is a golden yellow, fuming, and very corrosive acid, smelling strongly of chlorine. Acidum Nitrohydrochloricum Dilutum, U. S. P., is made by mixing 40 c.c. of nitric acid with 180 c.c. of hydro- chloric acid, and when effervescence has ceased adding 780 c.c. of distilled water. BROMINE— BROMUM, U. S. P. BROMIN. Br = 80. Specific Gravity 2.99 at 15° C. (59° F.). Density of Vapor 80. 116. History and Occurrence. — Discovered by Balard, in sea-salt, in 1826. It never occurs native, but is found combined with the alkaline metals and magnesium in sea-water, certain salt springs, and the ashes of sea-weeds. Preparation. — Sea-water or brine, which contains chlorides, bromides, and iodides of K, Na, Ca and Mg, is evaporated down, so that some of the constituent salts are separated by crystalliza- tion. The evaporation takes place first in large iron pans, and, after allowing the salts to settle, the liquor is further evaporated in a series of wooden tanks, five in number, which are heated by steam pipes ; these tanks are placed at different elevations, one above the other. The liquor remains one day in each tank, and when it reaches the lowest, or fifth tank, it contains only a few of the more soluble salts, chiefly bromide of magnesium. The crystals are removed from each tank when the liquor is drawn off. This last mother liquor is called bittern. The bittern is treated with chlorine gas, which liberates bromine. MgBr, + O, = MgClj + Br,. It is then shaken up with ether, which dissolves the bromine and rises with it to the surface. Then it is separated with pipettes, mixed with potassium hydroxide, and evaporated to dryness, leaving potassium bromide. 3Brj + 6KOH = sKBr + KBrOj + sH^O. SKBr -f KBrOs -|- heat = 6KBr + 3O. BROMINE. 119 The potassium bromide is then treated with manganese dioxide and sulphuric acid, which liberates the bromine in a pure state. 2KBr + MnO, + 2HjS04 = K^SO^ + MnSO< + zBfi + Br,. Properties. — Bromine is a heavy, dark-red, mobile liquid, evolving, even at ordinary temperatures, a yellowish-red vapor, highly irritating to the eyes and lungs, and having a peculiar, pungent, suffocating odor like that of chlorine. It is soluble in thirty parts of water, readily soluble in alco- hol, ether, carbon disulphide, and chloroform, imparting its color to the solutions. It is completely volatilized on exposure to air or to heat. It destroys the color of litmus and indigo, and colors starch solu- tion yellow. Chemical Properties. — The chemical properties of bromine aresimilarto those of chlorine, but somewhat feebler. Bromine is poisonous. It may be recognized by its color, odor, or by the yellow or brown color of its solution in chloroform. It forms a yellow or orange color with starch paste. A solution of argentic nitrate precipitates it from its solutions, as a yellowish-white powder, which is soluble with difficulty in ammonium hydroxide. 117. Hydrogen Bromide. — Hydrobromic Acid (HBr). This acid may be prepared by treating phosphorus, immersed in cold water, with bromine, and distilling the resulting liquid. The bromine combines with the phosphorus, forming PBrs, which is decomposed by the water into phosphoric and hydro- bromic acids. PBr^ -I- 4HP = H3PO, + sHBr It may also be prepared by the action of dilute sulphuric acid (7 parts acid to one of water), upon a hot solution of potassium bromide. (Squibb). 2KBr -f- HjSOj =• 2HBr + KjSO^ Another method is to pass sulphuretted hydrogen through an aqueous solution of bromine. Br^ + HjS = 2HBr + S Or by double decomposition between potassium bromide and tartaric acid. KBr -I- HjC4HPj=HBr + KHQHiOj Bitartrate of potassium precipitates and leaves HBr in solu- tion. The disadvantage of this method is that some of the bitartrate remains in solution. Diluted Hydrobromic Acid is 120 MEDICAL CHEMISTRY. official. It contains lo per cent, of absolute hydrobromic acid. It is a clear, colorless liquid, having properties closely resem- bling those of hydrochloric acid. Its sp. gr. is 1.077 ^' ^5° C. (59° F.) The acids of bromine and their salts are analogous to the corresponding acids and salts of chlorine. Hydrobromic is a monobasic acid, and forms salts called bromides. 118. Tests for Bromides. — i. With silver nitrate, a yel- lowish-white ppt. of silver bromide is produced, which is in- soluble in nitric acid, and sparingly soluble in ammonia water. 2. Treated with chlorine water, the bromine is liberated, which may be dissolved by shaking with chloroform, ether or carbon disulphide. IODINE.— lODUM, U. S. P. lODIN. 1=127. Specific Gravity 4.948. iig. History and Occurrence. — Iodine was discovered by Courtois in the ashes of sea-weeds in 1812. It occurs in certain mineral springs with chlorine and bromine, but in less quan- tities. It is obtained mostly from the ashes of certain sea-weeds, collected on the shores of Scotland and France. Preparation. — The sea-weed is first dried in the sun, and then burned in shallow excavations, at a low heat, so as not to volatilize the iodine. The ash (called "kelp") is then leached with water, whichdissolves out the salts, and the solution is evapor- ated in open pans, so as to separate the othpr crystallizable salts. The mother liquor, called "iodine ley," which still contains some sodium carbonate, hyposulphite and sulphide, is mixed with }i of its bulk of sulphuric acid and allowed to stand 24 hours. Decomposition of the above named salts takes place, with the evolution of CO2, SO^ and HjS. The liquid, which contains iodine as sodium iodide, is then put into a retort, and treated with manganese dioxide and some more sulphuric acid, and heated. The iodine now distils over and is condensed in suit- able condensers. 2NaI + aH^SOi + MnO^ = Na^SOj + MnSO, + 2HjO + I^. Iodine is a bluish-black crystalline solid, occurring in bright scales or tablets, which emit even at ordinary temperatures a very irritating, pungent vapor. When heated it melts at 114° C. IODINE. 121 (237.2° F.) and is gradually dissipated in the form of a beautiful violet colored vapor, of the density of 126.53. 120. Medical Uses. — It is used externally as a counter- irritant and discutient ; internally, as an antizymotic and altera- tive. In large doses, it acts as an irritant poison. It is elimi- nated by the kidneys, saliva and faucial mucous membrane, but not by the skin. In administering it, silver spoons should be avoided, as it attacks them. The following three preparations of free iodine are official : Tinctura lodi, a solution in alcohol (70 gms. to 1000 c.c). When freshly made it is precipitated from this solution with water, but after some time it undergoes changes which prevent this. The so called colorless tincture is made by adding am- monium hydroxide to the above tincture, in sufficient quantity to decolorize it by converting the iodine into ammonium iodide. Liquor lodi Compositus (Lugol's solution), is a solu- tion of iodine and potassium iodide in water. Iodine 5 gms., KI, 10 gms. Distilled water q. s. to make 100 gms. Unguen- tum lodi contains 4 per cent, of iodine, rubbed up with potas- sium iodide and water and mixed with lard. 121. Hydric Iodide, or Hydriodic Acid (HI). — A so- lution of this acid is prepared by passing hydric sulphide through water containing iodine in suspension, until the iodine disappears, and then filtering from the precipitated sulphur. I2 -f HjS = 2HI -f S. The acid, when pure, is a colorless gas, fuming in the air, hav- ing a penetrating odor resembling in most of its properties those of hydrochloric acid, although less stable and less active. Solu- tions of hydriodic acid are very prone to decomposition, with liberation of free iodine. Syrupus Acidi Hydriodici is official ; it is made by mixing an aqueous solution of potassium iodide with an alcoholic solution of tartaric acid. The mixture, is cooled by ice water, the precipitate separated by filtering, and syrup added. This syrup contains about i per cent, by weight of absolute hydriodic acid. The reaction which takes place in the above process is thus expressed : KI + H^QH.Oe = KHC.H^Os + HI. The iodides of potassium, sodium, iron, lead, mercury, arsenic, ammonium and sulphur are used in medicine. The following compounds are also known : ICl, ICI3, ICI5, IBr, IFI5 and NI3. The last is a very explosive compound. II 122 MEDICAL CHEMISTRY. 122. Tests for Iodine and Iodides. — i. Free iodine turns gelatinized starch blue. 2. To a solution containing free iodine, add a (ew drops of carbon disulphide, and shake. The carbon disulphide will fall to the bottom of the vessel in the form of a bead, of a beautiful violet color. Chloroform may be used instead of the carbon disulphide. 3. To a solution of an iodide add a little chlorine water, and test for free iodine, as above. 4. To a solution of an iodide add nitrate of silver solution ; a pale yellow precipitate will form, which is insoluble in nitric acid and in ammonia water. 5. Acetate of lead gives a yellow precipitate of lead iodide. GROUP VI.— NON-METALLIC MEMBERS. Oxygen, O = 16 Sulphur, S ^ 32 Selenium, Se = 79 Tellurium, Te = 128 The elements of this group are dyad, tetrad or hexad, with the exception of oxygen, which is always dyad. They all combine with hydrogen in the proportion of RHj. With the exception of HjO their hydrides have acid properties. Oxygen is the most electro-negative and tellurium the least so. OXYGEN. Symbol, O. Atomic Weight, 16 (15.96). Molecular Weight 32. Weight of I liter, 1.43 grams. 16 grams = ii.iS liters under standard temperature and pressure. 123. Occurrence. — Oxygen was discovered by Priestly, in England, in 1774, and at the same time by Scheele in Sweden, independently of each other. It exists in the air in the free or iincombined state, mixed with nitrogen and small quantities of other gases. It enters into the composition of a great variety of compound bodies, such as minerals, vegetable and animal bodies. Water is eight-ninths, sand one-half, and alumina one-third oxygen, by weight. OXYGEN. 123 124. Preparation. — Oxygen maybe prepared : — First. — By heating mercuric oxide in a retort or flask, when it breaks up into oxygen and black mercurous oxide ; or, if the temperature be high, into oxygen and metallic mercury. 2HgO = 2Hg + O,. Second. — By heating black manganic oxide (MnO^) to red- ness, in an iron or clay retort, when it gives off a part of its oxygen. . sMnOj = MdjOj + O2. Third. — By decomposing acidulated water with a current of Fic. 43. electricity. The oxygen obtained in this way is very pure, but the method is too slow for ordinary use. Fourth. — A good method, and the one most often employed, is by heating potassium chlorate. 2KCIO3 = 2KCI + 3O2. The evolution of the gas takes place more regularly and at a lower temperature, if the chlorate be mixed with ferric oxide, cupric oxide, or manganic dioxide. In practice, the last is generally used in the proportion of one part of the oxide to two or three parts by weight of the chlorate. The manner in which the oxide acts is somewhat obscure, for it seems to undergo no change in composition, and is found to be unaltered in the resi- due left in the retort. 124 MEDICAL CHEMISTRY. The process may be conducted in a round-bottom glass flask, furnished with a large-size delivery tube, provided that the heat be carefully regulated and not allowed to become too high. The gas is collected in an inverted jar in a pneumatic trough. See Fig. 43- One kilogram of the chlorate ought to yield about 140 liters or 5 cu. ft. of oxygen. 125. Properties, — Oxygen, when pure, is, at ordinary tem- peratures, a colorless, transparent, odorless, tasteless gas, slightly heavier than air. Its sp. gr. is 1. 10563. Water dissolves three per cent, of its volume, at ordinary temperatures. Under a pressure of 300 atmospheres, and at a temperature of — 140° C, it condenses to a transparent liquid whose specific gravity is 0.9787 (Pictet). Liquid oxygen boils at — 184° C. ( — 299° F.) under atmos- pheric pressure, and its absolute boiling point, above which it cannot be condensed to a liquid, and known as the critical temperature, is — 113° C. ( — 203° F.). Every gas seems to have a critical temperature peculiar to itself. Oxygen is mag- netic. The magnetism of the atmospheric oxygen is equal to that of a layer of iron covering the surface of ihe earth o. i milli- meter in thickness. Oxygen forms oxides of all the known elements except bro- mine and fluorine. Its range of affinities, and its energy of combining power are its characteristic chemical properties. Most elements combine directly with it, especially at high tempera- tures. When this oxidation is accompanied by light and heat it is called combustion. A body is said to be combustible when it unites readily with oxygen, and liberates light and heat in so doing. A combustible body usually requires to be heated to a more or less elevated temperature before it will be acted upon by atmospheric oxygen ; but when the process has once begun, it is kept up by the heat generated in burning. Some bodies, not usually regarded as combustible, will burn when heated to a red heat and plunged into an atmosphere of pure oxygen ; as, for example, a steel watch spring or small iron wire, so treated, will burn with great brilliancy. Bodies which burn in air with difficulty, burn in pure oxygen with great readi- ness. Oxygen is the great supporter of combustion, but the action of oxygen and the combustible body are mutual. A jet of air may be burned in a jar of illuminating gas or hydrogen as readily as these last burn in the air. Oxidation often takes place slowly, and the heat produced, although the same in both OXYGEhf. 125 cases, passes off into the air or surrounding bodies, so that the temperature does not rise much above that of the air. This is sometimes termed slow combustion ; or, more commonly, oxidation. Most ordinary combustibles contain carbon and hydrogen, and in such cases the results of the process are carbon dioxide and watery vapor. In case. the combustible contains sulphur, it becomes sulphurous oxide ; if nitrogen, it becomes either free nitrogen or ammonia, according as the oxidation is complete or incomplete. The respiration of animals is similar in effect to combustion. 126. Uses. — The uses of oxygen are very many. The oxy- gen taken into the air vesicles of the lungs passes through their thin walls, by diffusion, into the blood. There it combines with the haemoglobin and circulates with it throughout the body, as- sisting in burning up the waste products of the broken-down Fig, 44. tissues. It is eliminated from the body as carbon dioxide and water. One hundred volumes of arterial blood from a dog contain twenty-two volumes of oxygen (Gehaut), and this quantity varies with the amount of haemoglobin or with the red corpus- cles of the blood. Oxygen is used in the compound blowpipe, with hydrogen or illuminating gas, to obtain a high temperature for working plati- num or the production of the lime light. The gases are stored in separate receptacles under pressure, and are mixed in the blowpipe immediately before burning. The construction of the blowpipe is shown in section by Fig. 44. For the production of light, the flame is projected upon a small cylinder cut from unslaked lime. The flame heats the lime to a brilliant white heat which gives an intense light. In the ordinary projecting lantern, the light from the heated lime is thrown through a lens upon the screen. Objects or trans- 126 MEDICAL CHEMISTRY. parencies placed in the light before the lens are then observed upon the screen. Oxygen, either pure or mixed with nitrogen or nitrous oxide, and condensed into cylinders, has been used with some success in the treatment of various lung affections. When taken in this way, it acts as a tonic and stimulant, by oxidizing the blood ; and, by forcibly inflating the lungs, it in- creases by several cubic inches the air capacity. In the air, the oxygen is mixed with nitrogen to dilute it and regulate its action. Oxygen is of use as a supporter of combus- tion, to afford us artificial heat and light. With this heat we drive our steam engines, warm our houses, smelt our ores and cook our food. 127. Ozone. — If a series of electric sparks be passed, for a few minutes, through a portion of air or oxygen gas confined in a tube, it acquires a peculiar pungent odor, exhibits proper- ties which it did not previously possess, and undergoes a contrac- tion in volume. The same odor is usually detected in the air in the neighborhood of a frictional electrical machine while in operation ; or in the gas given off by a mixture of potassium permanganate and sulphuric acid ; K,MnO„ + 3H,S0, = K^SO, + 2MnS0, + 3H, O + O, f O3 0,= 0=0 03 = o£^\ or, when phosphorus, partially covered with water, is exposed to the air and allowed to undergo slow oxidation ; or by the electrolysis of water containing sulphuric and chromic acids. Ozone can often be detected about a galvanic battery, using as the exciting fluid a solution of sulphuric acid and potassium dichromate. Ozone has been prepared in the pure state by passing ozonized oxygen through a tube cooled by liquid oxygen to — 184° C. ( — 299° F.). Thus prepared, it is a steel blue liquid boiling at — 106° C, and evaporating into a blue gas. The density of the gas is 24, and its molecular weight is there- O . fore 48, or I ) O. O ^ The ozone of the air never exceeds one part in 700,000. It is most" abundant in May and Tune, and least in December and January. 128. Properties. — The properties of ozone are those of oxygen, intensified. It is a very powerful oxidizing agent, tar- HYDROGEN AND OXYGEN. I27 nishes silver and mercury, sets iodine free from potassium iodide, and is rapidly destroyed by contact with easily oxidizable or- ganic matters, and by a temperature of 149° C. (300° F.)- In this last case, it is reconverted into oxygen. It is a strong bleaching agent. It is soluble in oil of turpentine and in ether. In preparmg ozone from oxygen, a contraction takes place, and it again expands on being reconverted into ordinary oxygen. This shows that it is a condensed form of oxygen. Ozone is ij^ times heavier than oxygen, and its molecule is represented by q__V) or O3. 129. Tests. —The presence of ozone may be detected by its action upon a paper saturated with a solution of potassium iodide and boiled starch paste. This paper becomes blue by its action, owing to the liberation of iodine, which gives a blue color with starch. A piece of reddened litmus paper saturated with potass, iodide is also blued.. A paper moistened with an alcoholic solution of guaiacum is also changed to a light blue by its action. A piece of paper impregnated with a solution of manganous sulphate or lead hydrate turns dark brown or black in its presence. These reactions disappear when the air is heated to 260° C. (500° F.). Ozone is found in the air, especially after thunder storms, and when in appreciable quantities, acts as a purifier of the air, destroying, by its oxidizing action, many forms of organized germs hurtful to animal and vegetable life. On this account, it has been regarded as a valuable antiseptic and disinfectant. As it is very irritating to the mucous mem- branes, and when present to any considerable extent causes distressing coryza, or even haemoptysis, it is to be recommended with caution. HYDROGEN AND OXYGEN. Two compounds of these elements are known. Hydrogen oxide, or water, H.^0. Hydrogen peroxide, or oxygenated water, H.^02. HYDROGEN OXIDE, OR WATER. 130. Occurrence. Water is so widely distributed in nature, that it is almost universal. It exists in the three states of solid, liquid, and gas or vapor. It occurs in the solid form, below the temperature of 0° C. (32° F.), and asliquid between 0° C. (32° F.) and 100° C. (212° F.;and as vapor above 100° C. (212° F.). In the form of vapor 128 MEDICAL CHEMISTRY. it exists in the air at ordinary temperatures. It is poured into it from combustion, in various manufacturing processes, from vol- canoes, by spontaneous evaporation from the surface of the ground, bodies of water, and leaves of foliage. Seven-eighths of the entire human body is water. Potatoes contain J5 percent. ; watermelons, 94 per cent, and cucumbers 97 per cent. It en- ters into the composition of many rocks, and forms a necessary part of many crystals, where it is known as water of crystalliza- tion. 131. Composition. — The composition of water may be de- termined in two ways: by analysis or by synthesis. If a current of electricity be conducted through a vessel of water, slightly acidulated with sulphuric acid, the water will be decomposed into the two gases, hydrogen and oxygen, in the proportion of two volumes of the first to one of the second. If, now, these gases be mixed together in the same proportion, and an electric spark sent through the mixture, they recombine with an explo- sion. If equal volumes of the two gases be used, there will remain, after the explosion, one-fourth as much gas as was taken, which, on testing, will be found to be oxygen. These two experiments show that the proportion of the gases, by volume, must be two of hydrogen to one of oxygen. On weighing the two gases, we find that the oxygen weighs eight times as much as the hydrogen ; or, by weight, water is composed of -I oxygen and ^ hydrogen. The recombination is conducted in the eudiometer of the con- struction represented by Fig. 46 and the decomposition in the apparatus shown in Fig. 45. For the synthesis, of the water, the mixed gases are introduced into the graduated limb througli the stop cock at the top. The wires connected with a small in- duction coil, are connected with the two platinum wires soldered into the glass just below the stop-cock, and which are separated within the tube by a space about -jVi^f ^n inch. On connecting the coil with the wires from the battery, a spark is sent across the space between the platinum wires, which ignites the gases. In Fig. 45 the wires are seen to pass through the tubes at the bottom and terminate in two strips of platinum foil, from which the gases escape to the top of their respective limbs. If the grad- uated limb in Fig. 46, containing the gases to be combined, be surrounded by a larger tube, through which steam from a kettle is kept passing, and the gases are measured before and after the explosion, at the same temperature, it will be found that the steam produced by the combination of the oxygen and hydrogen. HYDROGEN AND OXYGJEN. 129 will occupy- two-thirds of the volume of the mixed gases before the explosion. (See Art. 91). That is, the two volumes of hydro- gen and the one volume of oxygen have formed two volumes of steam or vapor of water. Applying the law of Avogadro, it will be seen that there are the same number of molecules of water produced as there were of hydrogen taken. Now, as we have seen in Part II of this book, the hydrogen molecule contains Fig. 46. two atoms, and the molecule of water must contain two atoms of hydrogen. By the same reasoning, it may be shown that the molecule contains but one atom of oxygen ; or, the formula is HjO. 132. Preparation. — Water may be prepared in several ways by chemical means. First. — The simplest method is the direct union of the gases. 2H2 + O2 = 2H2O. Second. — It is always produced by burning hydrogen gas, or any combustible containing it, in the air, and may be condensed J 3© MEDICAL CHEMISTRY. by conducting the products of the combustion through a tube or flue kept cool by immersing it in cold water. CH + 20, Marsh Oxygen. = COj + 2H,0. Carbon Water. Gas. Dioxide. Third. — Water is produced as one of the products of the ac- tion of an acid upon a base, or metallic oxide. Thus: — K— O— H + HNO3 = KNO3 + HjO. Potass. Hydric Potass. Water. Hydroxide. Nitrate. Nitrate. Fourth. — The reduction of a metallic oxide by hydrogen or some organic substance containing it. CjHjO + 6CuO at red heat = 3Cuj + 2COj +3HjO 2CuO + 2Hj = CUj + 2Hj6. 133. Properties— Physical. — When pure, water is a colorltbs, transparent, mobile liquid, without taste or odor. When viewed in large quantity, however, it has a bluish color. It is a poor conductor of heat and electricity. When water is cooled down below 0° C. (32° F.) it assumes the solid state, called ice. When the temperature is raised to ioo°C. (212° F.) in ordinary conditions, it assumes the gaseous state, called steam. This point is called the boiling point. (See Art. 27.) The boiling point is higher than 100° C. under an increased pressure. Solid matter in solution raises the boiling point and lowers the freezing point. Water at a temperature of 4° C. (39. 2° F.), is taken as the unit of specific gravity of liquids and solids. At this temperature it possesses its greatest density. When it is heated above or cooled below this point, it expands and becomes less dense. Water is 773 times heavier than air at o°C., and 11,147 times heavier than hydrogen. Water expands quite rapidly and with great force on solidifying, and hence ice is lighter than water. This expansion is supposed to be due to the greater space required for the molecules in arranging themselves into crystals. The form of the crystal of water is hexagonal. This may frequently be seen in small snow-flakes received upon a dark surface ; the lines of the three equal axes can often be seen with great distinctness. The variations in the boiling point of water are much greater than those of the freezing point, but this last is subject to slight variations of temperature. Water may be cooled in capillary tubes to — 15° C. (s° F.) before it solidifies, if the tubes remain HYDROGEN AND OXYGEN. I3I at rest ; but if they are agitated, when at this low temperature, the water will instantly solidify. The agitation favors the move- ment of the molecules into the position to form crystals, and hence large bodies of water freeze at a higher temperature when agitated by a gentle breeze than when the air is very calm. Al- though converted into vapor most rapidly at ioo° C, water (even ice and snow) undergoes evaporation at all temperatures, espe- cially when the air is dry. Owing to its great solvent power for solids, pure water is never met with in nature. There are com- paratively few substances which are totally insoluble in water. When we wish to prepare pure water, we generally resort to the process of distillation, rejecting the first 20 per cent, of that which distils over, and also the last 20 per cent. It is by no means an easy matter to prepare absolutely pure water, even by this pro- cess ; but, by conducting the process carefully with the above precautions, we may obtain a water pure enough for all ordinary chemical purposes. Pure water is generally selected as the sol- vent of chemical substances which are to be submitted to any chemical change, because the reactions take place more readily in solution than when in the solid state, and because water is a neutral, body, which does not complicate the result by taking part in the action itself. The vapor of water is transparent, in- visible and colorless. Its density is 9, and its sp. gr., referred to air, is 0.6234. One volume of water will produce 1696 volumes of steam, or, approximately, one cubic inch of water will pro- duce one cubic foot of steam at 100° C. (212° F.), and absorbs 536.0 units of heat. Chemical Properties. — We have already referred, in speak- ing of the preparation of water, to some of its chemical proper- ties. It unites directly with many metallic oxides to form bases or hydroxides, and to some oxides of the metalloids to form acids. CaO + H2O = CaOjHz = base. SO3 + H2O = HjSOi = acid. CO2 + H2O = H2CO3 = acid. It enters into a feeble union with most metallic salts in solution, and separates with them when they cryslallize, as water of crystallization. Certain substances exhibit a marked tendency to combine with water, or to absorb it from the air, and are used in the laboratory as drying agents. Among these are calcium chloride, sulphuric acid and phosphoric pentoxide. 132 MEDICAL CHEMISTRY. 134. Natural Waters. — As already stated, natural waters are never free from dissolved impurities. They contain gaseous, liquid and solid impurities, varying according to the source from whence derived, the temperature, the nature of the soil or rocks over which they have flown or the state of the air at the time. Natural waters may be divided into potable (or drinkable), mineral and saline. 135. Potable Waters. — To this class belong well and spring waters, river water, lake water and ice water. The purest natural waters are rain and snow water from mountainous and country districts. The purity of rain water varies with the locality where it falls. In the neighborhood of large cities, where the air is charged with the products of large factories, etc., it will contain whatever of these can be washed out of the air. Sulphuric acid, for example, is comparatively abundant in the air of large cities. The rain water of London, as given by Dr. R. Angus Smith, contains 20.5 parts per million, while that of inland places in England contains only 5.5 parts; and that from inland places in Scotland, only 2 parts ; while from Glas- gow it contained 70 parts. The source of the sulphuric acid is mostly from the combustion of coal containing sulphur. The chlorides in rain water, princi- pally sodium chloride, vary with the distance from the sea coast. Ammonium salts, nitrates and nitrites are found in small quantities, derived from decomposing organic matter and from the combustion of coal. Another source of these com- pounds is the oxidation of a small quantity of the nitrogen of the air by ozone generated by lightning in its passage through it. Rain water also contains more or less dust and organic matter, which it washes out of the air in falling. The gases found in rain water are carbon dioxide (CO2), nitrogen, oxygen, and sometimes in cities, sulphur dioxide (SOj), and hydrogen sulphide (H,S). CO, 2.4 I Peligot's analyses show Oxygen 6.59 >-c.c. per liter. Nitrogen 14. ) It will be noticed that the proportion of oxygen in the air of rainwater is about twice as great as that of the atmosphere. Rain water, as ordinarily collected on roofs of houses, is very much contaminated with both organic and mineral matter washed HYDROGEN AND OXYGEN. I33 from the roof on which it falls. It is very liable to become pu- trid from the decomposition of this organic matter, and to breed the larvse of certain insects. Melted snow furnishes a water even ,purer than rain water, especially if we collect that which falls toward the end of a storm. 136. Ice water varies very much in purity, according to the purity of the water from which the ice is obtained. Ice is always purer than the water from which it is formed, and when obtained from clear lakes or rivers it is often the purest of natural waters, owingto the fact that in the crystallization of water, or freezing, it leaves part of the dissolved solids and gases in the remaining water. The absence of the usual gases, however, renders ice water flat to the taste. 137. Spring and ^A^ell waters are simply rain water which has been filtered through a more or less thick layer of soil. The nature and quantity of the dissolved matters will depend upon the nature of the soil and rock through which it percolates or over which it flows. In large cities, where the soil is saturated with filth, the well waters are very impure ; while in well drained and mountainous country districts they are much purer. Dangerous organic mat- ter may filter through many feet of soil and poison the water of a well or spring. Shallow wells usually contain much more organic and less mineral matter than deep wells, and are there- fore more likely to contain dangerous or unwholesome matters. Shallow wells are essentially a pit for the reception and accumu- lation of the drainage from the surrounding soil. For conveni- ence they are usually situated near the dwelling, where the soil receives more or less household waste of various kinds, and are often placed near a cesspool or privy vault. The effect of the geological character of the soil is almost entirely obliterated by this local impurity. Such waters, even when disgustingly im- pure, are usually bright, sparkling and palatable, and are often much approved by those accustomed to their use. Deep wells may be regarded as those which draw their supply from a depth of 100 feet or more from the surface. In cases where the supply is drawn from below a dense bed of clay or of impervious rock, the well may be considered deep, when such supply is much less than 100 feet below the shrface. Deep wells may be regarded as artificial springs, as both are subjected to the same conditions. Artesian wells are artificial springs formed by boring into the earth in a low-lying district surrounded by high ground, until a layer of rock or gravel is reached, situated between two imper- 134 MEDlfcAL CHEMISTRY. meable layers and containing water. The strata must be so curved that their outcrop is on a higher plane than the surface of the well. In such cases the water rises to the surface without pumping, and its character is determined by the nature of the rocks in which the water is found. 138. Surface 'Waters. — These comprise river water, pond, lake and sea water. The water supply of large cities is usually taken from this class of waters, and consists of spring water, and rain water which has fallen upon a considerable surface of country. Surface waters usually contain a large proportion of organic and mineral matters. Surface water, draining from a cultivated dis- trict, contains more organic and mineral matter than that from uncultivated districts, and the character of it is considerably influenced by application of fertilizers to the land. River waters are often contaminated by the discharging of sewage and refuse into them from various manufactories along their banks. 139. Characters of a Good Drinking Water. — ist. It should be clear and limpid. Cloudy and muddy waters should be avoided, zd. It should be colorless. A greenish or yellowish color is usually due to vegetable or animal matter in solution, or to organisms. 3d. It should be odorless ; especially free from sulphuretted hydrogen or putrefactive animal matter. 4th. It should not be too cold, but should have a temperature of from 8° C. (46° F.) to 15.5° C. (60° F.). 5th. It should have an agreeable taste; neither flat, salty, nor sweetish. A certain amount of hardness and dissolved gases give a sparkling taste. It should contain from 25 to 50 c.c. of gases per liter, of which 8 to 10 per cent, is carbon dioxide, and the rest oxygen and nitrogen. The air of natural waters is richer in oxygen than the atmosphere above them, viz.: about 33 per cent, of oxygen and 67 per cent, of nitrogen, when the water is fully saturated, which is not always the case. Highly contaminated waters usually contain' less oxygen than the above proportion, because it is used up in oxidizing the organic matter. 6th. It should be as free as possible from dissolved organic matter, especially of ani- mal origin. 7th. It should not contain too great an amount of hardness. A certain quantity of saline matter is necessary, how- ever, to give it a good taste. It should not contain over 3 or 4 parts of chlorine in 100,000 parts of water. 140. Sanitary Water Analysis. — We have seen that natural waters are never pure, but contaminated by various kinds of foreign matter to which they have been exposed. These im- purities may be harmless to the human economy, or they may be HYDROGEN AND OXYGEN. 135 •very harmful. It is the object of the analyst to determine, as nearly as possible, the nature and amount of the impurities found in a water, so as to form an opinion as to its healthfulness. It has been proven, beyond doubt, that water is a fruitful dissem- inator of disease. It is believed thit the disease produced in such cases is due to microscopic organisms, and that the organic matter of the water simply furnishes a suitable solution in which they may live and grow. It is also known that these organisms grow best in solutions of animal organic matter, and this animal mat- ter may be the carrier of the disease germs ; hence, waters con- taminated with animal matters are looked upon as much more dangerous than those containing vegetable matter. If the above idea be correct, it is evident that chemical an- alysis cannot detect the disease-producing element, although it can tell pure from impure water. Several methods are in use among chemists for the purpose of forming an opinion as to the character of drinking waters. The elements usually relied upon in a sanitary examination, are total residue left on evaporation, the loss in weight of this residue on ignition at a dull red heat, the chlorides, the nitrates and nitrites, ammonia, organic carbon and nitrogen, and the quantity of oxygen the water will absorb from an acid solu- tion of potassium permanganate. Poisonous metals should, of course, be looked for where there can be any suspicion of their presence. 141. Total Residue. — The amount of residue left on evapo- ration serves, in a crude way, to indicate the amount of solids, but is only approximate and of no significance unless it reaches more than 30 or 40 grains per gallon. This residue will, of course, vary with the hardness, or, the amount of soluble constituents in the soil. By igniting the solids (heating them over the lamp) we may expel all volatile and organic matter, including the water held by the calcium sulphate, at the temperature of 100° C. (the temperature generally used in drying the residue), some carbon dioxide from carbonates, and oxides of nitrogen from nitrates and nitrites. The residue left after ignition gives a rough idea of the mineral matters present, and the loss on ignition should never reach 50 percent, of the total residue. Something may be gained by observing the color of the residue left on evaporation, which should be of a pure white color. It should blacken but very little on heating, and should give off no fumes. The residue of bad waters blackens very considerably, or gives off the odor of burning horn, or of nitrous fumes. 136 MEDICAL CHEMISTRY. 142. Chlorine in potable waters is very largely derived from ■ the sodium and potassium chlorides of urine and sewage. The average amount of chlorine in urine is not far from 5 parts per 1000 or 500 parts in 100,000 parts of water. The average found in sewage is about 11.5 parts per 100,000. Over 5 parts of chlo- rine per 100,000 may be considered, in most cases, to be due to pollution of the water by sewage or animal excretions. This will be modified by the chlorine found in the purest waters of the same class of that district. The source should always be taken into account in judging of the quality of a water. Prox- imity to the sea does not materially affect the amount of chlorine in well waters. Too much dependence cannot be put upon the amount of chlorine in a water, as a means of judging of its purity, for vegetable matter may exist in dangerous quantity without its presence being indicated by the chlorine present. Chlorine is estimated by a standard solution of argentic nitrate. This solution is prepared by dissolving 4.8022 grms. of crystallized silver nitrate in a liter of vfater. Each c.c. of this solution will precipitate o.ooi grm. of chlorine. 100 c.c. of the vfater under examination is measured out into a beaker, just enough potassium chromate is added to give a distinct yel- low tint, and then the above silver solution is run in from a graduated burette, a fi w drops at a time, until a slight red tint appears, showing that the chlorine has been precipitated and that the silver is beginning to precipitate the chromic acid as red silver chromate. From the amount of silver solution used we may easily calculate the amount of chlorine present, for i c.c. of the silver solu- tion precipitates i milligram of chlorine. The number of c.c. of the silver solution used multiplied by 10 will give the mgrms. of chlorine in I liter of water, or the parts per million. With many natural waters it is best to evapor- ate off about half the volume before titration. 143. Hardness. — The hardness of water is produced princi- pally by tlie acid carbonates and the sulphates of calcium and magnesium. The acid carbonates are decomposed by boiling, and the neutral salts precipitated : — CaH,(COs), = CaCOj + Hfi + CO,. Hardness due to these salts is called " temporary," while that due to the sulphates of these metals is called " permanent." The hardness of water seems to have little or no influence upon the health of those who use it. Temporarily hard waters may be softened by adding lime in sufficient quantity to neutral- ize the excess of carbonic acid in the water, when the carbonate (CaCOa) or (MgCOj) is formed, which settles to the bottom. The alkaline carbonates (Na^COa) and (K5CO3) may be used to precipitate permanent hardness and soften the water. Wood HYDROGEN AND OXYGEN. I37 ashes, which contain the latter of these salts, is frequently used by washerwomen to soften water for washing clothes. Hardness is estimated by means of a standard solution of soap. Many samples of water possess both temporary and permanent hardness and sometimes it is desirable to estimate them separ- ately. For this purpose the total hardness is estimated in one sample, and the hardness in another sample is determined after boiling and separating the temporary hardness. The difference of the two gives the temporary hardness. When soap is added to a hard water the calcium and magnesium salts are precipitated according to the following equation : H,Ca(C03)2 + 2NaC,„H3,Oj = Ca(C,3H3A)2 + Na.CO, Hp + CO, or Calcium Sodium Stearate. Calcium Stearate. Sodium Acid Carbonate. Carbonate, CaSOl + 2Nar,„H,A = Ca{C,,H,fi,), + Na.SO,. Calcium Sodium blcarate. Calcium Stearate. Sodium Sulphate. Sulphate. The calcium stearate in both cases is precipitated as a white curdy-like mass. The hardness is estimated by taking advantage of these reactions. There is required for the estimation a standard solution of soap made as follows. lo grams of shavings from a new cake of air-dried castile soap, are dissolved in a liter of about 60 per cent, alcohol. Filter if not clear and keep it in a tightly stop- pered bottle. To determine the strength of the soap solution dissolve exactly i gram of pure CaCOj in a little HCl, neutralize with ammonium hydroxide and add sufficient water to make i liter. I c. c. of this solution will contain the equivalent of o. 001 gram of calcium carbonate. Measure out 10 c. c. of this solution into an 8 oz. glass stoppered bottle, add about 90 c. c. distilled water, and run in the soap solution, drop by drop, from a bu- rette, shaking aftej eafch addition, until a lather is formed which remains for five minutes. Note the number ofc.c. of soap solu- tion used, and calculate the amount of calcium carbonate preci- pitated by I c. c. of the soap solution as follows. We now repeat this experiment with 100 c. c. of pure distilled water. The amount of the soap solution required to produce a perma- nent lather, in the distilled water must be deducted from the amount used in the above test. Usually it will be not far from one-half to one c. c. The 10 c. c. of the solution of CaCOa, used in the above mentioned test, contained the equivalent of 10 ragrms. of CaCOs. Suppose in the above mentioned test 8.5 c. c. of the soap solution were used to produce a permanent froth and 0.5 c. c. were required by the distilled water. Then 8 c. c. were used to precipitate the .010 gram of CaCOs. Each 138 MEDICAL CHEMISTRY. I c. c. of this solution precipitated }i of 10, or 1.25 mgrms. of CaCOs. The estimation of the hardness of a water is conducted exactly as the above process for standardizing the soap solution, except that 100 c. c. of the water under examination is placed in an 8 oz. bottle and the soap solution run in from a burette until a permanent lather is obtained.' Read off the number of c. c. of soap solution added, and multiply this by 10, which will give the hardness reckoned as CaCO^ in mgrms. per liter, or parts per million. The hardness of waters varies so much that no average can be given. A water that doss not contain more than 50 parts of hardness per million may be regarded as soft water, while one containing 150 is a hard water. 144. Nitrates and Nitrites. — These salts are usually looked upon as evidences of former contamination of a water by nitro- genous organic matter. The decomposition of organic matter of animal origin, in waters containing dissolved oxygen, yields nitrous and nitric acids, which combine with bases present to form salts of these acids. Rain water contains a small quantity of these acids, but a larger quantity indicates that the water is undergoing, or has undergone, a natural process of purification from animal matters. This change is partially due to direct oxi- dation, but more particularly to the action of certain microor- ganisms which have the peculiar power of converting nitrogenous organic matter into nitrites and nitrates, in both water and soil. The process of disposing of nitrogenous organic matter, in natural waters, or animal refuse, is to convert the nitrogen into am- monia, then into nitrous acid and finally into nitric acid. The quantity of these compounds found, usually indicates the amount of matter th'js decomposed. This purifying process goes on more slowly in river and lake waters thin in ground water, because the exposure to oxygen in the latter is more complete while filtering through the soil, thin in a body of water. Diep wells may be allowed to contain more nitrates than shallow ones, for the or- ganic matter may all be destroyed by filtering through the soil into a deep well, while in the shallow one some organic matter, germs, and spores capable of causing disease, may pass unde- coraposed through the shorter distance. A careful estimation of nitrates gives, therefore, considerable knowledge of the past history of a water, and is regarded by chemists as of great im- portance. A. very ea?y anl Jelicite test for nitrates ani nitrites in water, is the follow ing : Make a solution of dipheaylamin in pure, strong sulphuric acid free from HYDROGEN AND OXVGEN. I 39 nitric or nitrous acids, as shown by a duplicate test with distilled water, adding a little pure water to make a clear solution. To the suspected water add one-half its volume of the sulphuric acid, then a few drops of the above solution. If nitrates or nitrites are present, a deep blue solution will be formed at once. This test may be used by any one, and will give some idea of the safety of a drinking water. To detect the presence of nitrites, a solution of meta-phenylendiamin in pure sulphuric acid may be used. When nitrites are present the solution as- sumes a yellow to brown color, according to the quantity present. If to 100 c. c. of water we add i c. c. each of a saturated solution of naph- thylamin chloride, sulphanilic acid, and dilute hydrochloric acid (i to 3 of water) there appears, if nitrites are present, a pink color, the intensity of which is proportional to the quantity present. A quintitative estimation of the nitrites requires the following reagents : I. Sulphanilic acid I grm. dissolved in 100 c. c. of hot water. 2. Naphthal- amin hydrochlorate, 0.5 grm. dissolved in iod c. c. of boiling water, kept in a glass stoppered bottle, with a little pulverized carbon added, to decolorize the solution. Filter or decant from the carbon when required for use. 3. Dissolve .275 grm. of dry silver nitrite in hot water, add slight excess of sodium chloride and dilute with pure water to 250 c. c. After the silver chloride his settled, remove 10 c. c. of the clear solution and dilute with water to 100 c. c. One c. c. of this solution, which is used in the analysis, is equiva- lent to .01 mgrm. of nitrogen. The process : 100 c. c. of the water is placed in a cylinder, previously cleansed, and two drops of strong hydrochloric acid added. Add I c. c. of the sulphanilicacid solution, followed by i c.c. of the solution of naphthalamin hydrochlorate. Mix and cover to exclude dust, and let stand for 30 minutes. One c. c. of the standard nitrite solution (No. 3) is placed in another glass cylinder, water free from nitrites is added to make 100 c. c, and treated with the same reagents as the above. At the end of a half hour the two solu- tions are compared. The colors are brought to the same tint by diluting the darker, and the calculation made as to the amount of nitrogen, as nitrite, in the 100 c. c. Suppose, for example, the 100 c. c. of the water requires ddution to 125 c. c. in order to make this tint agree with that produced -by I c. c. of the standard sodium nitrite solution, which contains .oi mgrm. of nitrogen as nitrite; then loo : 125 : : .01 : x = .0125. That is, the water contains in 100 c. c. .0125 mgrm. of nitrogen in the form of nitrites, or .125 mgrm. per liter, or .125 parts per 1,000,000. Leeds places the limit for American rivers at .03 per 100,000 and Mallet places the average in good waters at about .014 parts per million. When the quantity exceeds .02 in 100,000 it is considered as indicating previous contamination by organic matter whose nitrogen has been converted into nitrous acid. The nitrates are estimated by acidulating 500 c. c. of the water with oxalic acid, pouring half of it into each of two wide-mouth bottles. Into one of these put a copper-zinc couple, made by taking a piece of sheet zinc (4 by 6 in.) and rolling it into a loose coil, and immersing it in a 1.5 per cent, solution of copper sulphate, until the surface is covered with an even layer of copper. Cork both bottles and let stand for 24 hours. Remove 50 c. u. from each bottle and Nesslerize as directed under ammonia. The difference between the two readings gives the ammonia due to the reduction of the nitrites and nitrates present. The nitrogen in the previously determined nitrites must be subtracted, when the remaining nitrogen will be that from the nitrates. If I40 MEDICAL CHEMISTRY. the nitrogen, as nitrates, exceeds six parts per million, the water is suspected of having been polluted. 145. Moist combustion or oxygen consuming power. — By this is meant the oxidation of the organic matter found in a water, by adding to it a measured quantity of potassium per- manganate, with some sulphuric acid, and determining the oxygen absorbed from this salt by the organic matter present. This method cannot distinguish between vegetable and animal matters, neither will it measure the oxygen consumed in oxidiz- ing nitrites to nitrates, or ferrous to ferric salts. In the presence of these salts it may give erroneous results. Most chemists regard the process as of some value in giving an idea of prob- able pollution by organic matter, as it has been shown that dangerous organic matter is more easily oxidized than that which is harmless. The quantitative process requires the three following solutions: I. Potassium permanganate solution. It is conveniently made of such strength that l c. c. will yield 0.1 mgrm. of oxygen for oxidation. Such a solution will contain 0.3952 grm. of tlie salt in i liter of distilled water. 2. Solution of oxalic acid. Dissolve 0.7875 grm. crystallized oxalic acid in I liter of water. One c. c. of this solution, when titrated with the potassium permanganate solution, in the presence of sulphuric acid and while hot should just decolorize I c. c. of permanganate solution. 3. Dilute sulphuric acid, I part strong acid to 3 of water. Add enough permanganate solution to give a faint pink tint after standing four hours. Method of Procedure. — Measure 200 c. c. of the water under examina- tion into a half liter flask, and add 10 c. c. of the dilute sulphuric acid, and enough of the potassium permanganate solution from the burette to give it a marked red color. Boil for ten minutes, adding more of the permanganate solution from time to time, if necessary, to maintain a red color of about the same intensity. Remove the lamp, and add 10 c. c. of the oxalic acid solution to destroy the color, and then add more of the potassium permanganate from the burette until a faint pink tinge again appears. From the total amount of permanganate used deduct the 10 c. c. which was used up by the oxalic acid solution. The remainder will give the amount of permanganate used by the water, or the number of mgrms. of oxygen actually absorbed by the water. This quantity multiplied by S will give the number of mgrms. of oxygen absorbed by a liter of water under the above conditions, or the parts per million. Waters absorbing more than 2 parts of oxygen in i million should be considered as of doubtful purity. Those containing 5 parts should be regarded as organically impure. Leeds gives as a limit for American rivers from 5 to 7 parts per million. Another process allows the mixture of the water, acid and permanganate to remain at the room temperature for a longer time. Five stoppered bottles, holding 500 c. c. (a pint) are thoroughly cleansed with pure sulphuric acid. To each add 250 c. c. of the waters to be tested, and 10 c. c. of the sulphuric acid. Then add varying amounts of the per- manganate solution, say 2, 4, 6, 8 and 10 c. t. respectively. They should be HYDROGEN AND OXYGEN. I4I inspected at the end of i, 2, 3, 4 and 12 hours, and the effect noled. If all the bottles should be decolorized bef jre the end of the fourth hour, 10 c. c. is added to each, and the result again watched. In fairly good waters not more than the first 2 or 3 will decolorize in 4 hours. That is, 250 c. c. of water should not absorb more than 1. 5 to 2 mgrms of oxygen. This process is simple, and requires little skill when the solutions are ouce prepared. 146. Ammonia. — The spontaneous decomposition of organic matter in water, first affords aminonia, then nitrites, and finally nitrates. This fact is so generally conceded as to make an esti- mation of the ammonia found in a water, a very important part of the sanitary examination. The ammonia is geirerally spoken of as free ammonia, or more properly ammonium salts, and albuminoid ammonia, or more properly as ammonia from organic nitrogen. The sani- tary examination of a water should always include a quantitative estimation of the ammonia and organic nitrogen. The method adopted for this purpose is that known as the Wanklyn process, and is the one which yields the best results. The process requires several solutions and considerable care in manipulation in order that the results may be reliable. The solutions required are : i . Ness- ler's solution, made by dissolving 35 grms. of potassium iodide in 100 c. c. of water, and 17 grms. mercuric chloride in 300 c. c. of water. When solution is complete, add the latter solution to the former until a permanent precipitate is produced. Then dilute with a 20 per cent, solution of sodium hydroxide to I liter. Now add the mercuric chloride solution again until a permanent pre- cipitate forms. Let settle till clear, and decant and use the clear solution. It improves on keeping, and will delect extremely minute quantities of ammonia. 2. Sodium carbonate. A saturated solution of pure freshly ignited sodium carbonate in water free from ammonia. 3. Standard ammonium chloride solution. Dissolve .314 grm. of ammonium chloride in 100 c. c. of water, i c. c. of this solution is then diluted with 99 c. c. of ammonia-free water. This last solution will contain .00001 grm. of ammonia in each c.c. and is the solu- tion employed in the analysis. 4. Alkaline potassium permanganate. Dissolve 8 grms. of pure potassium permanganate crystals and 200 grms. of potassium hydroxide in water and mike up to a liter. The solution is putinti) a flask, or retort, and boiled. The distiilaies are collecled and tested wiih the Nessler's solution until they cease to give a reaction for ammonia, when it is ready for use. 5. Water free from ammonia. A good clear well or hy- drant water is treated with a few c. c. of the sodium carbonate solution, and dis- tilled until a small portion of the distillate shows no reaciion with Nessler's test. The remainder, except the last portion, will usually be found to be abso- lutely free from ammonia. Or, we may add to the water a few drops of strong sulphuric acid and distil, rejecting the first one-tenth of the whole volume^ when the remainder will usually be found to be free from ammonia. The process. 100 c. c. of pure distilled water is added to a retort holding about a half liter. To this is added 2 c. c. of the sodium carbonate solution. The retort is connected with a Liebig's condenser by an air-tight joint made 142 MEDICAL CHEMISTRY. by a piece of black rubber tubirg of large caliber slipping over both the retort and condenser. The beak of the retort is bent at such an angle that the lower end may be a,ttached to the block tin tube of the condenser as shown by (Fig. 47). A lamp is now brought under the reloit and the water rapidly boiled until 10 c. c. of it shows no reaction with Nessler's reagent. 100 c. c. of the water under examination is row put into the retort by means of a funnel, and the boiling continued slowly, removing the distillate when I o c. c. are collected. Four distillates of 10 c. c. each usually contain all the ammonia existing in the water as salts of ammonia. Many prefer to use 500 c. c. of the water instead of 100 c. c. and distill cff 50 c. c.,of the solution for Nesslerizing. The author Fig 47. prefers the smaller quantities, using smaller tubes graduated at 10 c. c. The process of Nesslerizing is conducted as follows: 0.5 c.c. of the Nessler's solution is measured into each of the four distillates and mixed by agitation. The weaker ammonia solution is now added to 10 u. c. of the ammonia-free water in another cylinder, until the color produced with 0.5 c. c. of Nessler's solution is equal to that in the first distillate removed. Each distillate is imi- tated by a known amount of ammonia in the same volume of liquid. Some chemists recommend to add '/^ of that found in the first distillate as an average amount to be found in the remaining ones. When about .40 c. c. have distilled over, the lamp is removed and 10 c. c. of the alkaline permanganate solution is added to the retort, and the distillation slowly continued, setting aside each HYDROGEN AND OXYGEN. 143 distillate « hen 10 c. c. are collected. These distillates are again Nesslerized as in the case of the firs-t dittillale. The color of each cylinder is imitated in other cylinders with a known amount of ammonia and the amounts so obtained are added together to obtain the total amount of amironia. After a little practice it will be easy to imitate the color of any distillate by this process. It is necessary to note not only the absolute quantity of albuminoid ammonia, but the rapidity with which it is set free and dis-tilled over. If it comes vety rapidly, it indicates that the organic matter is in a putrescent or decomposing condition. If, on the other hand, the ammonia distils gradually, it indicates the piesence of organic matter in a ctmparative stable or fresh condition. It is best, therefore, to keep the record of each distillate so that the rapidity with which the arrmonia is set fiee, as well as the actual amrunt, may be known. If the water yields no albuminoid ammonia, it is fiee from recently added or- ganic contamination. Usually, Tiowever, it gives a very .=mall amount. If it contain more than o.l mgrm. per liter the water is looked upon as suspicious, and is to be condemned when it reaches .15 mgim. per liter, or .15 part per million. When the free ammonia is present in considerable quantity, then the albuminoid ammonia becomes suspicious of contamination when it reaches over .05 mgrm. per liter. An opinion shculd not Le foimulated, however, without a knowledge of the source of the water examined. Free ammonia may exist in larger quantities in some deep wells without denoting dangerous contamination. 147. Biological Examination of Water. — In recent years it is customary to determine the nature and number of the microorganisms in water by the well-linown bacterio- logical methods. Surface waters and many well waters contain a variety of living organisms, which may be easily discovered by the aid of a microscope ; such as the daphniae, cyclops, desmids, algae, rotiferae, amoebae, etc. These organisms feed mostly on sus- pended organic matter, and are not regarded as especially harm- ful, except in the case of the entozoa. Dissolved organic matter in a state of decomposition is generally indicated by the smaller bacteria. The principal object in view, in these examinations, is to de- termine the number of organisms in a given volume, i c. c, of the water, and if possible to determine the character of these organisms. The cultivation of the organisms requires care and skill, and is even then open to great question as to the value of the results. Pathogenic bacteria have rarely been found by the method, and the chemical methods are still relied upon. While much is to be hoped for in the future, the process has not thus far given results which, taken alone, can replace the older chemical methods above referred to. We have thus briefly outlined the methods in use for testing drinking waters, for the purpose of giving the student some 14+ MEDICAL CHEMISTRY. knowledge of the subject, without going into tedious details, which are intended only for the chemist, and which do not come within the scope of this work. 148. Purification of Water. — Water may be separated from suspended impurities by filtration, i. e., bypassing it through any porous substance not soluble in water, as clay, sand, char- coal, brick, unglazed earthenware, unsized paper, etc. For filtering large quantities of water for cities or manufactories, sand or brick is to be preferred. For filtering water for family use, a brick partition two or four inches thick, built from wall to wall in a cistern, works well. The water is delivered in one apart- ment and pumped from the other for use. Or, a barrel, in the bottom of which several holes are bored, may be filled with alter- nate layers of gravel, sand and charcoal, and placed over the mouth of the cistern or reservoir, through which the water may be filtered. Such a filter, when freshly made, will remove a part of the dissolved organic matters as well as suspended matters. The silicated carbon filters found in the market, made of pul- verized carbon and cement, are much neater, and will also when new, oxidize a portion of the dissolved organic matter in passing the water through them. Porous stone filters, made from a silici- ous stone, are to be found in the market, which filter rapidly and very satisfactorily. Spongy iron filters, made by roasting hema- tite with coal, are still more active in destroying organic matter and putrefactive germs. But few of the various forms of com- mercial filters remove micro-organisms from water; on the con- trary, nearly all, after being used for a short time, begin to contaminate the water with microscopic organisms which they harbor in their pores. Sand filters are most efficient for filtering large quantities of water for rtie supply of cities. In some cities a process of "scouring," or agitation of the water with angular sand, is practised. In others there is em- ployed a combination of a precipitant of the organic matter and filtration. The precipitants are either alum or a ferric salt. The Hyatt and National systems operate on this principle, and are said to be efficient, where the amount of water to be treated is not too great. In the Anderson system the water is agitated with iron borings, in a revolving iron cylinder, which forms a certain amount of ferrous carbonate from the carbonic acid of the water. The temporary hardness is thus largely removed by removal of the carbonic acid. On exposure to air the ferrous carbonate is oxidized and ferric hydroxide is precipitated. HYDROGEN AND OXYGEN. I 45 2FeC03 + O + 3H,0 = Fe,(OH)j + 2CO,. The water is then filtered through sand. The organic matter is largely removed by this process, as is shown by analysis, and the organisms as well. The time of contact of the water and iron is about 3 to 4 minutes. This process has been tried in some large cities and is highly spoken of. Organic matter may be largely removed from water by precipi- tation with alum or ferric chloride. When alum is added to a water, it is decomposed, with the formation of a hydroxide which, as it settles, carries down with it all suspended matters and a large part of the dissolved organic matter and microorganisms. From one to two grains to the gallon is sufficient. Ferric salts behave in a similar manner. Filtration through granulated iron, kept clean by agitation, and afterward filtering through sand, serves to remove a large part of the organic matter and microbes. We have already referred to methods of precipitating the hardness from water. Distillation, as a means of purifying water, has also been referred to. Freezing purifies water, and removes, to a considerable degree, the mineral as well as organic matters; but freezing cannot make a dangerous water safe. Numerous instances show that disease may be communicated as surely by ice as by unfrozen water. 149. Mineral 'Waters. — Under this name are included such waters as, from some dissolved substances, have a greater or less therapeutical value. These vary so much in the character of the dissolved substances, that no exact classification of them can be made ; but they may be roughly classified as follows: — ist. Carbonated Waters, those which are charged with carbon dioxide or carbonic acid. 2d. Sulphuretted Waters, those which contain sulphides of hydrogen, or one of the alkaline metals, in notable quantities. They are used for baths as well as for drink- 3d. Alkaline Waters, those containing considerable quanti- ties of carbonates or bicarbonates of the alkaline metals — sodium, potassium, or lithium. 4th. Saline 'Waters, those containing the neutral salts, such as the chlorides, bromides, or iodides of the alkalies or alkaline earths. 5th. Chalybeate Waters, those containing some one of the compounds of iron. Closely allied wiih these in proper- ties are those containing manganese. 13 J 46 MEDICAL CHEMISTRY. 6th. Acid Waters, those containing free mineral acids, such as hydrochloric or sulphuric acids. 7th. Thermal Waters, or such as come to the surface at a temperature above that of 20° C. (68° F.) Some of these springs contain so little mineral matter as to be of no import ; the only value, if any, being in the tempera- ture. They are used principally for baths. 150. Official Forms. — Aqua. Natural water in the purest attainable state. Aqua destillata. Take of water 80 pints. Distil two pints, reject, then distil 64 pints. (U. S. P.) The transparency or color of distilled water should not be affecte'd by lime water ; nor by HjS, BaClj, AgNOg, or (NH4)2C204. The term aqua, in the U. S. P., is used to designate a solu- tion of a gaseous or volatile body in water, as aqua ammoniae, aqua chlori. Liquor, a solution of a fixed or solid body, as Liquor Ferri Nitratis, Liquor Plumbi Subacetatis. A Decoction is a solution made with boiling water, usually of a vegetable product. An Infusion is a solution formed by sub- jecting the body for a short time to either cold or warm water. Maceration is the long-continued action of water at the ordi- nary temperature. Digestion, the same with hot but not boil- ing water. Lixiviation or leaching is the process of pouring water through a porous mass of any substance, for the purpose of dissolving out soluble matters. 151. Physiological Use. — Water exists in all the tissues of the body, and in all foods and drink. A healthy adult takes, on an average, about 2.5 liters of water in 24 hours ; and loses by the skin, lungs, kidneys and faeces a little more than thisj the excess coming from the oxidation of the hydrogen of the food and tissues. Water constitutes about from 65 to 70 per cent, of the whole body, being in slightly larger proportion in the young than in the adult body. The water in the tissues serves as a sol- vent for the various proximate principles* intended as nourish- ment for the tissues, or coming from their waste, and intended for excretion. The evaporation from the skin serves to carry off the superfluous heat of the body. (See Art. 29.) 152. Hydrogen Peroxide (H2O2). — The simplest way of preparing a diluted solution of this body is to pass a stream of CO2 through water containing barium peroxide in suspension. BaOj + CO2 + HjO = BaCOj + Hfi^. The insoluble barium carbonate may be separated by filtration, best through asbestos filters. This solution may then be evapo- HYDROGEN AND OXYGEN. I 47 rated in a partial vacuum. In its purest form, it is a syrupy, colorless liquid, having an odor resembling that of chlorine or ozone, and a tingling metallic taste. It is still liquid at — 30° C. ( — 22° F.), bufat a temperature of 100° C. (212° F.) it changes rapidly into water and oxygen. This change takes place gradu- ally at ordinary temperatures. In diluted solution it is much more stable, and may be boiled without suffering decomposition. The solutions of this substance are decomposed by many fine metallic powders. In most of its reactions it acts as an oxidizing agent. Argentic oxide, however, is reduced to the metallic state by it. Tests. — To the suspected solution, add a little starch solution, then some potassium iodide, and finally a few drops of a solution of ferrous sulphate. If any hydrogen peroxide be present a blue color will appear. Very delicate. Uses. — Oxygenated water, or hydrogen peroxide, is used as a bleaching agent for the hair and skin, converting brunettes into blondes. It is often used to renovate old pictures, the whites of which have become dingy. It has been used as a disinfecting application to ulcers, in ozsena, diphtheritic and scarlatinal sore throats, or where the membrane has invaded the nose. Also used as a test for pus in urine, with which it causes an effer- vescence. Mixed with ether, it forms the so-called " ozonic ether," used with tincture of guaiacum as a test for blood color- ing matter, with which they strike an indigo blue color. OXYGEN COMPOUNDS OF THE ELEMENTS OF THE CHLORINE GROUP, OR GROUP VII. Fluorine forms no oxides or hydroxides. 153. Chlorine and Oxygen. — There are several oxides of chlorine known. CljO, Hypochlorous Oxide or Anhydride. CljOj, Chlorous Oxide or Anhydride. CI2O4, Chloric Tetroxide. They are all unstable compounds, very prone to decomposi- tion, and of little importance. 154. Hypochlorous Anhydride, CI^O, obtained by acting upon mercuric oxide with dry chlorine, is a blood-red mobile liquid below 20° C. (68° F.). HgO -1- 2CI2 = HgCI, + afi. Above this temperature it is a yellowish, pungent gas, resemb- ling chlorine in many of its properties. It is a more powerful bleaching and disinfecting agent than chlorine, owing to the ease 148 MEDICAL CHEMISTRY. with which it decomposes. Water dissolves zoo times its volume of it, forming a colorless solution of hypochlorous acid. It sometimes decomposes witli a slight jar, or even spontaneously, with the separation of chlorine and oxygen. Hypochlorous acid is unimportant, but it forms a series of salts called hypo- chlorites.' A solution of the sodium salt, liquor sodae chlo- ratse (U.S. P.), (Labarraque's solution), potassium hypochlorite, liquor potassii chloratae, and calcium hypochlorite, occur- ing in chloride of lime, are the most important compounds. 155. Chlorous Anhydride, CI2O3, maybe formed by treat- ing potassium chlorate, KCIO3, with dilute nitric acid in the presence of arsenious oxide. It is a greenish-yellow explosive gas, soluble in water, with which it unites to form chlorous acid, HCIO2, a very unstable body which has not been isolated, but which forms chlorites. None of these salts are of importance. 156. Chloric Tetroxide, CI2O4, may be obtained, as a yellow explosive gas, by treating potassium chlorate with strong sulphuric acid. It is a powerful oxidizing agent. Below — 20° C. ( — 4° F.) it is an orange-red liquid. It forms no corresponding acid. 157. Chloric Acid (HCIO3) and perchloric acid (HCIO,) are also known, but are very unstable, and like those before mentioned, are powerful oxidizing agents. Potassium chlorate is the only salt of note, which will be described under potassium. 158. Bromine and Oxygen. — No oxides of bromine are known. There are, however, three acids known, corresponding to those of chlorine. They are hypobromous acid, HBfO, bromic acid, HBrO,, and perbromic acid, HBtOi. They are of little importance, and but one salt of the three acids is of interest to the physician, and that is sodium hypobromite, NaBrO, used as a reagent for the estimation of urea. It is pre- , pared in solution by adding bromine to a solution of sodium hydroxide, having care to keep the mixture cool by immersion in cold water. 2NaOH + Br^ = NaOBr + NaBr + H^O. 159. Iodine and Oxygen. — Thtre are three or four unim- portant and unstable oxides of iodine known. I2O3, IjOs, and possibly IjO,. Two oxygen acids are known, iodic, HlOj, and periodic, HIO4. Theifirst is obtained by treating iodine with nitric acid, and the second by passing chlorine through an alka- line solution of sodium iodate. The first, when pure, appears as a white crystalline solid, and the second as colorless crystals. Both are very soluble in water, are easily decomposed, and form corresponding salts. SULPHUR. '49 SULPHUR. S = 32. Sp. gr., 2. Density of vapor, 32. Melts at 115° C. (239° F.i Den- sity of vapor at 500° C. (932° F.) = 95.94 = S^. At 1000° C. (1832° F.) :^ 31.98 = 82. 160. Occurrence. — Sulphur was known to the ancients. It occurs in volcanic regions, and is brought most!)' from Sicily and Iceland. The sulpliur occurs native, mixed with clay, from KEFINI.NG OF SULPHUK. which it is separated by distillation. This element also occurs as sulphates in the minerals, gypsum, CaS0i.2Aq, Banle, BaSOj, and as sulphides of iron, copper, nickel, and in fact, with many of the metals; also as a precipitate from sulphur waters. The following reaction explains its deposition from such waters; 2H,S + O, = 211,0 + S,,. 161. Preparation. — It is prepared from the native sulphur mixed with more or less earth, found in volcanic regions 150 MEDICAL CHEMISTRY. of Sicily, by distilling it from the non-volatile impurities. A second distillation is necessary to prepare the refined sulphur of the market. The second distillation is conducte.d in a retort, the vapor being carried into a large chamber (Fig. 48), where, if the process is conducted slowly, it collects in the form of a crystalline powder called flowers of sulphur, or sulphur sublimatum U. S. P. If the process is conducted more rapidly the chamber becomes hot, and the sulphur then con- denses to a liquid at the bottom, whence it is drawn off into moulds, forming ordinary roll sulphur or brimstone. Sulphur is also obtained in some localities from iron pyrites, by piling it in heaps mixed with wood, to which fire is applied. The ore gives up a part of its sulphur, which melts and runs into cavities made under different parts of the heap. 162. Properties — Physical. — Sulphur, in its ordinary form, is a lemon-yellow solid, melting at 115° C, (239° F.), and boil- ing at about 440° C. (824° F.), giving ofif a brownish-yellow vapor, which in condensing returns directly to the solid state. Sulphur is brittle, tasteless, odorless, a non-conductor of heat and electricity, and generates negative electricity when rubbed. It is insoluble in water, and almost so in alcohol. It is slightly soluble in anilin, phenol, benzene, benzine and chloroform. The best solvent is carbon disulphide, 100 parts of which dissolves 37 parts at ordinary temperatures. AUotropic Forms. — Sulphur is capable of existing in three allotropic modifications ; two crystalline, and one amorphous and plastic. The first variety is that found native, and occurs as octahedra. (See Art. 85.) It is freely soluble in carbon di- sulphide, from which the crystals separate on evaporation. The second variety is produced by crystallization from sulphur melted at high temperatures. This variety occurs as yellowish-brown, transparent monoclinic prisms, of sp, gr. 1.98, insoluble in car- bon disulphide, and gradually changing into the first variety. Since it crystallizes in two distinct systems, sulphur is said to be dimorphous. By heating sulphur, it melts at about 115° C. (239° F.) to a yellowish liquid; on raising the temperature to about 225° C. (437° F.), it becomes viscid and dark colored, and cannot be poured from the vessel : at a higher temperature, approaching its boiling point, it again becomes liquid. If sul- phur, in this second liquid state, be suddenly cooled by pouring into cold water, it assumes a soft, plastic, transparent mass, capable of being moulded like wax. This variety, like the pre- SULPHUR. 151 ceding, gradually changes into the first variety, becoming opaque, yellow and crystalline. Chemical. — When heated in the air, sulphur takes fire and burns with a pale blue flame, and evolves abundant fumes of sul- phurous anhydride, SOj. It is generally strongly electro-negative and resembles oxygen in many of its compounds. In a few com- pounds it is electro-positive. It unites directly with many of the metals, especially when in the melted state, some metals taking fire and burning readily in its vapor. It forms the basis of a large and useful class of compounds, many of.which resemble in com- position the corresponding compounds of oxygen. Thus, carbon disulphide, CS2, corresponds to carbon dioxide, CO2. Corresponding to hydrogen oxide, HjO, we have hydrogen sulphide, H^S, and to cyanic acid, CNOH, we have sulpho-cyanic acid, CNSH. Corresponding to carbonic acid, H2CO3, we have sulpho-carbonic acid, H2CS3. 163. Uses. — Sulphur is used in the arts, in the manufacture of sulphuric acid, H2SO4, as a bleaching agent for straw and woolen goods, and in the manufacture of matches and gun- powder. In medicine it is used as a parasiticide, and as a gentle laxative, although not as frequently as formerly. It is innocuous. 164. Official Forms. — 1._ Sulphur sublimatum, com- mercial flowers of sulphur. 2. Sulphur lotum, washed sulphur. Flowers of sulphur usually contain small quantities of sulphurous oxide, which is removed by digesting for three days in a dilute mixture of ammonia water and water, then thoroughly washing with water to remove the ammonia. 3. Sulphur prae- cipitatum, lac sulphuris, milk of sulphur, is made by boiling for one hour, sulphur with fresh slaked lime suspended in water. 3Ca(OH)2 + 6S2 = 2CaS5 + €38203 + 3H2O. The filtered solution of CaSj and CaSjOs is then diluted and treated with dilute hydrochloric acid as long as a precipitate forms. aCaSj -f CaS203 + 6HC1 = sCaClj -|- sH^O -f 6S2. The calcium chloride, being very soluble, remains in solution. The sulphur must be thoroughly washed with water, until free from acid. It is a fine white powder, easily suspended in water and viscid liquids. 4. Unguentum sulphuris, U. S. P., con- tains 30 per cent, of washed sulphur and 70 per cent, of ben- zoinated lard. Sulphur lotum enters into pulvis glycyrrhizae compositus. 152 MEDICAL CHEMISTRY. 165. Sulphur and Hydrogen. — Two compounds of sulphur and hydrogen are well known — hydrogen sulphide, HjS, and hydrogen persulphide, HjSa. The first only is of sufficient in- terest to merit description here. Hydrogen sulphide, hydro- sulphuric acid and sulphuretted hydrogen are synonymous terms. It is found in volcanic gases, in some mineral springs, and as a result of the putrefactive decomposition of organic matter containing sulphur. At an elevated temperature, the two elements may be. made to unite directly. 1-66. Preparation. — The usual method of preparing it is to act upon a sulphide, usually ferrous sulphide (FeS), with dilute sulphuric acid. 167. Properties. — H2S is a colorless, transparent gas, of an unpleasant odor resembling that of rotten eggs, soluble in water, to which it imparts acid properties. It is somewhat heavier than air, its density being 17 and its sp. gr. 1.177. At a tem- perature of — 74° C. ( — 101.2° F.), or under a pressure of 17 atmospheres at 10° C. (50° F.), it condenses to a colorless, mobile liquid, which at — 85° C. ( — 121° F.) becomes an ice- like solid. It burns with a blue flame, producing water and sulphurous oxide or anhydride, SOj. 2H2S + 3O2 = 2H2O + 2SO2. If the supply of oxygen is deficient, H^O is produced, while the sulphur is deposited free. It is decomposed by chlorine, bromine, iodine and oxidizing agents in general. It is also de- composed by sulphurous oxide. A solution of sulphuretted hy- drogen does not keep long when exposed to the air. The oxygen of the air unites with the hydrogen of HaS, forming water, and causing the sulphur to be precipitated. 2H,S + O, == 2H,0 + S,. . When the gas is allowed to bubble through a solution of an alkaline hydroxide, the sulphur and oxygen exchange places with the formation of a sulphydrate. KOH -j- HjS = KSH + H^O. When it is passed through a solution of a metallic salt, it forms, in many instances, a sulphide of the metal. CuSO^ + HjS == CuS + HjSO^. It is, on this account, largely used in the laboratory as a reagent SULPHUR. 153 for the separation of the metals from one another. Minute quantities of HjS may be detected by its odor, or by the brown or black color it imparts to a paper moistened with a solution of plumbic acetate. Its principal use is as a reagent. 168. Physiological. — When inhaled, it is not an irritant, but a narcotic poison, even when largely diluted with air. Ac- cording to Faraday, birds die in air containing -ysstt of it. and dogs in one containing -g^. According to Letheby, human beings cannot live in an atmosphere containing more than one per cent. Its action is principally a reducing one upon the haemoglobin of the blood, and prevents this fluid from absorbing oxygen, although it probably does not combine with it. (Wurtz. ) Hydrosulphuric acid is formed in the intestine, from the decora- position of albuminous matters, especially where there is any impediment to digestion, or to the onward movement of their contents. It also sometimes occurs in abscesses, and in the urine and bladder. This gas is almost a constant ingredient in the gas of sewers and privy vaults, existing free, or combined with ammonium as ammonium sulphydrate. Poisoning by this gas may be acute or chronic. The latter is more common, producing a febrile state, with malaise and general debility. The fatal effects of sewer air are sometimes due to this form of poisoning. Occasionally this gas is so concentrated in sewers that those who enter them suffer with acute poisoning, fall almost instantly, and if not rescued, die in a short time. The treatment, in such cases, should con- sist in pure air, or oxygen, with brandy and water. Chlorine water, or a mixture of potassium chlorate and dilute hydrochloric acid, may be administered internally. When taken by the stomach, it is almost harmless ; and in the form of natural min- eral water, it is a popular remedy for rheumatism, gout and certain skin diseases. 169. Sulphur with Chlorine, Bromine and Iodine — Sulphurous Chloride (SjClj). — A yellow, volatile, fuming liquid, having a powerful solvent power for sulphur and sulphuric chloride, and formed by distilling sulphur in an atmosphere of chlorine gas. It is decomposed by water, but mixes with benzene and carbon disulphide. SCI2, and several oxychlorides, are known. Bro- mine unites directly with sulphur to forma red, unstable liquid, probably consisting mostly of S^Brj. Iodine and Sulphur combine directly when gently heated, even under water. When 80 parts of iodine and 20 parts of 14 4- S- 6. H,SO„ H,S,03, H,S,0„ I: 9- 10. 154 MEDICAL CHEMISTRY. sulphur are heated logelher, they form a steel-gray crystalline mass, SJ,, sulphuris iodidum (U. S. P. and B. P.), said to be a powerful remedy in certain skin diseases. It melts at 60° C. (140° F.), and is insoluble in water. Oiher iodides have been described, but are unimportant. 170- Sulphur and Oxygen. — The following oxides of sul- phur are known : — SOj, Sulphur dioxide, or Sulphurous anhydride. S2O3, Sulphur sesquioxide. SO3, Sulphur trioxide, or sulphuric anhydride. Acids of Sulphur :^ 1. HjS, Hydrosulphuric acid. 2. HjS02, Hyposulphurous acid. 3. HjSOj, Sulphurous acid. Sulphuric acid. f This acid has not Thiosulphuric acid (Hyposulphurous) -j been isolated, but Pyrosulphuric acid. Nordhausen. ( its salts are known. Dithionic acid. Trithionic acid. Tetrathionic acid. Pentathionic acid. A few only of this large number of compounds are of sufficient importance to be described here. 171. Sulphurous Oxide or Anhydride, SO2 — Prepara- tion. — I. It may be prepared by burning sulphur in the air. 2. By heating sulphuric acid with copper turnings, sulphur, or carbon. According to the U. S. P., and B. P., charcoal is used : — 2H2SO4 + C = aHjSOj + COj. 172. Properties—Physical. — Colorless gas, having a pun- gent, suffocating odor, and a disagreeable acid taste. It is very soluble in water, with which it combines to form an unstable sul- phurous acid, acidum sulphurosum, U. S. P., emitting the odor of gas. It is very soluble in alcohol. Sp. gr. 1.35. The density of the gas is 32 ; sp.gr. (Air ^ i) 2.234. Below — 10° C. (14° F.), it is a colorless mobile liquid, which solidifies at -75°C.(-io3°F.). Acidum sulphurosum is a liquid containing not less than 6.4 per cent, of the gas, by weight. Chemical. — SOj is non-combustible, and will not support combustion or respiration. It combines with water to form sul- phurous acid, and hence is an anhydride. Nascent hydrogen re- duces it to H2S and water. It is a valuable reducing agent, easily taking up oxygen to form sulphuric anhydride or acid. It is a SULPHUR. 155 bleaching, disinfecting and deodorizing agent of considerable value. It bleaches moist vegetable colors, although not perma- nently destroying them. The colors may be restored by an alkali, or weak chlorine water. It is used principally for straw, silk and woolen goods. It decomposes hydrogen sulphide, and when concentrated, destroys many forms of microscopiclife, and is much used as a disinfectant of rooms after contagious diseases. Although not as active as chlorine, it is preferred, because it does not corrode metals or bleach fabrics, if dry. Ta apply it, close the room and burn about three pounds of sulphur for 1000 cu. ft. of air, leaving the room closed for 6 to 8 hours. Sulphurous acid forms two series of salts, the neutral and the acid salts. They are used as antiferments or antizymotics. 173. Uses. — They are used internally, and as sulphites and thiosulphates (hyposulphites) in zymotic diseases, gastric fer- mentations, sarcina, etc., also locally, in erysipelas and poisoned wounds. The sulphites and thiosulphates of the alkaline metals are used for the same indications as the acid. Hyposulphite of sodium is prepared by digesting sulphur with sulphite of sodium. It is used in photography and electro-metallurgy, as a solvent for the silver salts. Dose of the acid, 4 c.c. (f3j) largely diluted. Dose of sulphite or hyposulphite, 0.650 to 3.000 (gr. x to 1). 174. Sulphuric anhydride CSO3), is obtained by distilling Nordhausen acid, as white, silky prisms, hissing when dropped upon water, from the energy with which they combine. Melts at 18.3° C. (650 F.), and boils at 43° C. (iio°F.). It does not redden dry litmus paper. It has a powerful affinity for water, absorbing it from the atmosphere. It is only of scientific interest. 175. Sulphuric Acid, Hydrogen Sulphate, Oil of Vitriol, HjSOi = 97.82. — The commercial acid is prepared in large quantities directly from sulphur or iron pyrites. The pro- cess is conducted in large chambers lined with sheet lead. Into these chambers sulphurous oxide is poured from a furnace in which sulphur is burned or pyrites roasted, along with a free supply of air. S., -|-20j=2S0j. In the same furnace is placed a crucible containing sodium nitrate and sulphuric acid, for the purpose of preparing and volatilizing nitric acid, which is carried into the chamber with the SO2 and air. zNaNOj + HjSO^ = Na,SO< -|- 2HNO3. 156 MEDICAL CHEMISTRY. The nitric acid gives up a part of its oxygen to oxidize a por- tion of the SO2 to SO3. 2HNO3 + 3SO, = 3SO3 + H,0 + NjO,. The SO3 then combines with the water thus produced, and more water is supplied by a jet of steam thrown constantly into the chamber. SO3 + H,0 = H,SO,. The N2O2 has the power of taking up oxygen from the air and becoming NjOj, NjOj + Oj = NjO^. which in turn parts with this oxygen to oxidize a new quantity of SO,. NA + 2S0j = NA + 2SO3. Thus the process is kept up as long as the SO2, air, steam and NjOj are supplied. The acid condenses with the water on the floor of the chambers, and when it reaches a sp. gr. of 1.55 (chamber acid) it is drawn off into large leaden pans and evaporated to a sp. gr. of 1.746, (pan acid), when it begins to dissolve the lead. It is then drawn off into platinum stills and the concentration completed. 176. Properties. — The commercial acid is a heavy, corrosive, oily liquid, often of a brownish tint, and has a sp. gr. of 1.830 to 1.845. I' mixes with water in all proportions, combining with a certain quantity to produce H^SOj, and finally ortho- sulphuric acid, HjSOe, with the production of considerable heat. The concentrated acid attracts moisture, and is used as a desic- cating agent. Gases, allowed to bubble through it, are deprived of their moisture. It chars organic matter and corrodes animal tissue. Paper dipped in a cooled mixture of two parts of the acid and one of water, and then quickly washed, is converted into parchment paper. Starch or cellulose, when boiled with the dilute acid, is changed, by hydrolysis, into glucose or grape sugar ; and cane sugar into glucose and levulose. In this action it behaves like the unorganized ferments, diastase, pepsin, trypsin, etc., and illustrates the so-called catalytic action of certain bodies. The dilute acid is a solution of HeSOg in water. On boiling this with the above bodies, it imparts a portion of its water to the organic body, and takes up more water from the solution to supply its place. Sulphuric acid is a powerful dibasic acid, forming a series of salts called sulphates, all containing SULPHUR. 157 the SOi group of atoms. It also forms a series of acid sulphates — HKSOj, HNaSO^. Owing to the powerful affinities of this acid, it usually removes the metal or positive radical from other acids and sets them free. It forms insoluble precipitates with solutions of barium, lead, strontium and with calcium in concen- trated solutions. This should be remembered in adding it to prescriptions. The other sulphates are soluble in water. 177. Medical Effects. — When dilute, tonic and astrin- gent. Concentrated, or in large doses, it is a corrosive poison. Antidote — lime, magnesia, sodium bicarbonate, or other alkaline body, best given in milk. 178. Official Forms. — Acidum sulphuricum, U. S. P., sp. gr. 1.84, is used only in making other preparations. It con- tains not less than 92.5 percent, by weight of absolute sulphuric acid. It is a colorless, inodorous, and very corrosive liquid, having an oily consistency, and a very strong acid reaction. Acidum sulphuricum dilutum, U. S. P., sp. gr. 1.070 at 15° C. (S9° F.), containing 10 per cent., H.^S04. B. P.. sp. gr. 1.094, containing 13 per cent. H2SO4. Acidum sulphuricum aromaticum, U. S. P., should contain abcmt 18.5 per cent, of absolute sulphuric acid, or about 20 per cent, of the official acid. It is an alcoholic solution, containing also tincture of ginger and oil of cinnamon. It contains ethyl sulphuric acid, H-0\s = Q 179. Tests for Sulphuric Acid and Sulphates. — i. Ba- rium chloride gives a white ppt., insoluble in all acids. 2. Lead acetate gives a white ppt., slightly soluble in hot con- centrated acids. 3. An insoluble sulphate maybe detected by fusing it together with some sodium and potassium carbonate, dissolving out the alkaline sulphate with water and testing with barium chloride. Fuming Sulphuric or Nordhausen acid (HjSjO,), is obtained by distilling ferrous sulphate The first portions are a white, crystalline solid, fusing at 35" C. (95° F.), and having the above composition. The commercial acid is a brown, oily, liquid, hissing when dropped into water. Some chemists regard it as a solution of SO3 in H2SO4. When heated, it gives off SOs and H^SO^. HjSjO, = HjSOj -I- SO3. IS8 MEDICAL CHEMISTRY. It is used in manufacturing alizarin, eosin, etc., and as a sol- vent of indigo. It forms a series of salts called disulphates. Selenium and Tellurium. Se 78.87. Te 125. These elements are rare and of no special interest to the phy- sician or pharmacist. GROUP v.— NON-METALLIC ELEMENTS. OR NITROGEN GROUP. Nitrogen, N = 14. Ill or V. Phosphorus, P = 31. HI or V. Arsenic, As = 75. Ill or V. Antimony, Sb = 120. Ill or V. Bismuth, Bi ^207.5 III or V. 180. Group Characteristics. — A well-defined group with nitrogen at the negative end and bismuth at the positive. The atomic weights form a graded series from 14.01 to 208.9. The first is a gas ; the second a volatile solid ; the third a volatile, crystalline, metallic-looking body, showing a slight tendency to alloy with metals and combine with acids ; the fourth less easily volatilized, crystalline, possessing a brilliant lustre, alloying with metals, and showing a tendency to act the positive rdle with acids; the fifth, also crystalline, having a metallic lustre, and showing more marked positive tendencies. They are all both triad and pentad, and form two series of compounds. The following will exhibit the relations of some of the most important compounds: — Hydrides. Chlorides. Oxides. Sulphides. NH, NCI3... N,0„ NjOj PH. PCI,, PClj •PA, pa' PA, PaSJ ASH3 AsClj, AsCl. ASjOj. AS2O5 ASjSg, As,S. SbHj SbCL, SbCL SbjOj, SUA Sb,S„ Sb,Sj ... BiCIj, ... BijOj, BijOj BijS,, ... NITROGEN. 1 59 NITROGEN. Fig. 49- Symbol, N. At. Wt. 14. Equivalence, I, III or V. Density, 14. Wt. of I liter, 1.256 grms. Sp. gr. (Air = i), 0.971. 181. Occurrence. — Exists free in air, mixed with oxygen. It is also found free in the gases of the stomach, large and small intestines, blood, the urine, etc. Combined, it occurs as nitrates of potassium, sodium and calcium ; in ammonia, and in vegetable and animal bodies of the proteid group. It was discovered by Rutherford, in 1772, who called it " Mephitic Air." 182. Preparation. — From the air, by burning phosphorus in a confined space until the oxygen is removed (Fig. 60), or by passing air over copper or iron turnings heated to red- ness ; the nitrogen pre- pared by both methods contains small quantities of other gases found in the air. To prepare it pure, heat ammonium nitrate (NH4N02). ~ NH^NOj + heat = 2HJ5O 183. Properties — Physical. — A color- less, transparent, odor- less, tasteless, incom- bustible gas, not a sup- porter of combustion or of animal respiration. It is not poisonous ; very sparingly sol- uble in water or alcohol. One part of water dissolves, at the ordinary temperature and pressure .025 part of this gas. Chem- ically, nitrogen is characterized by its inertness. It unites directly with magnesium, boron, vanadium and titanium. In- directly, it forms a great number and variety of compounds, many of which are unstable. Under the influence of electric discharges nitrogen can be caused to unite with hydrogen to form ammonia, NH,, and with oxygen to form nitrous oxide. From this source most of the nitrogenous products necessary to sustain plant life are primarily derived. j6o medical chemistry. THE ATMOSPHERE. The atmosphere is a colorless, invisible, odorless mixture of gases, which surrounds the earth. It is very elastic, and is there- fore most dense nearest the earth's surface, upon which it exerts a pressure of about fifteen pounds to every square inch. Air was first weighed by Otto Gerecke. looo c. c. of air ato° C. and 760 millimeters of pressure, weighs 1.293 gram. It is 14.42 times as heavy as hydrogen. 184. The Atmosphere is composed principally of nitrogen and oxygen mixed together in the proportion of 20.93 parts of oxygen, by volume, to 79.07 parts of nitrogen, and, by weight, 23 parts of oxygen to 77 parts of nitrogen. Although air is a mixture and not a definite compound, it is remarkably constant in composition. Regnault found in 233 analyses of air, at different times and places, that the per cent, of oxygen by volume varied between 20.908 and 20.999. That air is a mixture is proved by : ist, its gases are not present in the proportion of their atomic weights ; 2d, an air answering to all the properties of the atmosphere, can be made by a mechanical mixture of the gases; 3d, solvents for oxygen, as an alkaline solution of pyrogallic acid, remove this gas from the air ; 4th, each gas dissolves in water independently of the other, and with its own solubility ; thus by expelling the air from water, by_ boiling, and analyzing it, we find it to correspond to that calcu- lated from the known solubility of the two gases. (See Art. 79). The analysis of the air expelled from water shows 33 per cent, of oxygen and 67 per cent, of nitrogen; it is therefore, much richer in oxygen than the atmosphere. Owing to the rapid diffusion of the gases, the disturbances in composition due to the respiration of animals and to manufacturing processes, are soon re- stored. Besides the two chief gases found in the air, there are various other ingredients found in small quantities, as watery vapor, carbon dioxide, ozone, ammonia, nitric and nitrous acids, hydrocarbons, solid particles of dust, sodium chloride, vegetable germs or spores, bacteria, etc. Air in which animals are con- fined also contains some of the organic exhalation from their bodies. In the neighborhood of large cities, various other sub- stances are poured into the air from manufacturing establishments. The essential ingredients are oxygen, nitrogen, carbon dioxide, and watery vapor. The rest of those enumerated, may be re- THE ATMOSPHERE. l6l garded as accidental, and not essential to the life of plants and animals. 185. Watery Vapor. — The proportion of watery vapor in the air varies considerably with the temperature and locality. The air is seldom saturated in the daytime, and contains less in- land than near large bodies of water. The higher the temperature of the air the more moisture it will hold ; thus, at 0° C. (32°F.), I cu. metre (1.3 cubic yards) is saturated by 5.4 grams (83.3 grs.) of water, and at 25° C. (77" F.), the ordinary temperature, it requires 22.5 grams (347 grs.). Or, at 77° F., one cubic yard will be saturated by 267 grains of water, and one cubic foot by about 10 grs. In reality, the air will seldom be found to contain more than 60 or 70 per cent, of this amount. When one cubic meter (1.3 cu. yds.) of an atmosphere saturated at 25° C. (77° F.), is cooled down to 0° C. (32°F.), it will deposit, as dew, rain or frost, 22.5 — 5.4 = 17. i gms. (263.8 grs.). The temperature at which air begins to deposit its moisture, on being cooled, is called the dew point. The dew point will depend upon the amount of water actually present in the air. The amount of moisture is determined by passing a known volume of air through tubes containing calcium chloride, which absorbs the water. The increase in the weight of the tubes gives the weight of water. The amount of vapor in air varies from .3 to 1.6 per cent, by volume. The dampness of the air does not depend upon the amount of water it contains, but upon the degree of saturation. A cold damp air, when heated, becomes dry ; hence, the necessity of supplying moisture to the heated air in our rooms in winter. A very dry air irritates the air passages, produces dryness of the skin, and malaise. A very moist atmosphere checks evaporation from the skin and lungs, raises the bodily temperature, and soon becomes oppressive. A damp air favors the growth of many varieties of disease-producing organisms, as those of cholera, typhoid fever, and probably tuberculosis. 186. Carbon Dioxide. — The average amount of carbon di- oxide, CO2, in country air is 4 parts in 10,000, and varies from 3 to 6 parts. It is greater near large cities and manufactories ; greater during the night than the day on land, and the reverse on the ocean. Plants remove it from the air in the daytime, and the cooler water at night absorbs more than the warmer water during the day. (See Carbon Dioxide.) 187. Ammonia. — This exists in the air, in very minute quantities, principally in the form of carbonate, the result of the decomposition of animal and vegetable organic matters. I 62 MEDICAL CHEMISTRY. It is especially evolved from urinals, privy vaults and horse stables. It is washed out of the air by falling rain, and is taken up from the soil by plants. i88. Nitric and Nitrous Acids occur in extremely minute quantities, and are produced by the direct union of oxygen and nitrogen in the presence of watery vapor, under the influence of discharges of lightning. They exist principally in combination with ammonium. Hydrocarbons, the principal of which is marsh gas, are fre- quently found in the air of cities, coal mines, wells and swampy districts. It is produced by the decomposition of vegetable matter under water, and in some industrial processes. 189. Accidental Gases in the Air. — The gases generated in certain manufactures are sometimes allowed to escape into the air. Some of these are harmless and others hurtful. Among the first class may be mentioned carbon dioxide, when not in too large quantities, and ammonia. To the second class belong hydric sulphide, ammonium sulphydrate, sul- phurous oxide in large quantities, vapors of mineral acids, carbon disulphide, etc. Hydric Sulphide or Sulphuretted Hydrogen (H2S), is found in certain tunnels and mines, caused by the decomposi- tion of iron pyrites. It is also found in the air of some marshes and sewers. The symptoms produced by breathing small quantities of this gas, are those of debility and anaemia; in larger quantities, head- ache, vertigo, weak pulse, sweating and prostration. Ammonium Sulphydrate (NH^HS) produces nearly the same symptoms as hydric sulphide. It occurs in the air of sewers and privy vaults. Both these substances are easily destroyed by chlorine or sulphurous oxide. Sulphurous Oxide (SO^), unless in considerable quantities, and in a closed room, does not seem to have any deleterious effect upon the workmen. In bleachers it sometimes produces irritation of the bronchial tubes. Hydrochloric Acid, Nitric Acid, and Chlorine in con- siderable quantities are very irritating to the lungs and conjunc- tiva. Carbon Disulphide (CSj) produces unpleasant and delete- rious eifects upon workmen exposed to air containing it ; as headache, giddiness, nervous depression and loss of appetite. igo. Suspended Matters. — A great variety of solid par- ticles, or dust, are found in the air at all times. These consist of THE ATMOSPHERE. 163 fragments of wood, textile fabrics, metals, etc., pollen of plants, bacteria germs, etc. These suspended particles may be regarded as impurities, and many of them are injurious to health. Work- men in various trades are seriously affected by the dust to which they are exposed ; as miners, especially of lead and coal, grinders of metal, wool sorters, rag pickers, feather dressers, etc. The irritation of the dust of these and other trades may cause chronic bronchitis, emphysema, phthisis, or chronic poisoning. Germs of various kinds are believed to cause many of the contagious and malarial diseases, and may be carried some distance in the air. Some of these germs seem to be easily oxidized, while others are very persistent. The best disinfectants for their de- struction are free ventilation and consequent dilution with dry air, chlorine, bromine, iodine and sulphurous oxide. 191. Disinfectants, Germicides,* Antiseptics, De- odorizers. — The presence of odors and organized "germs," in the air often require the use of one of the above agents. Disinfectants are a class of bodies which are supposed to destroy the germs, and thus prevent them from causing their specific action either upon the human body, or in decomposable organic bodies or solutions. The most efficient of these is heat. Organized germs may be filtered from the air by passing it through cotton wool ; or they may be removed by enclosing the air in an air-tight box or chamber, the insides of which are moistened with glycerin. (Tyndal.) Ozone, chlorine, bromine, iodine, sulphurous oxide, mercury, zinc, aluminium, magnesium and calcium chlorides, potassium chlorate, potassium permanganate, carbolic, boric, cresylic and sulphuric acids, thymol, menthol, camphor, etc., are among the disinfectants most used. Antiseptics are agents which retard or entirely prevent putre- faction or growth of microscopic germs and organisms. While disinfectants destroy the cause of infection, antiseptics pre- vent the development of these causes. Low temperature retards putrefaction, and is, therefore, an antiseptic agent. These two terms are frequently used interchangeably. Asepsis is a condition of entire absence of any germs or cause of infection. Deodorizers are bodies used to destroy offensive odors. They may be either solid, liquid or gaseous. Solids — * A germicide is an agent which has the power of killing the germs, and thus preventing their growth. A disinfectant destroys the infectious properties of septic matter, whether this be due to germs or some other agent. 164 MEDICAL CHEMISTRY. dry earth, lime, charcoal, ferrous sulphate, carbolates of calcium, sodium and magn^ium. Liquids — solutions of plumbic nitrate (Ledoyen's fluid), zinc chloride (Burnett's fluid), potassium or sodium permanganate (Condy's fluid), a mixture of copper and zinc sulphates (Lenande's disinfectant), solutions of ferric chlo- ride, of ferrous sulphate, hypochlorites, etc., are among the best known. Gases — pure air, ozone, chlorine, bromine, and sul- phurous oxide are the most effective. Fumigations with tar, herbs, and various aromatic substances, only disguise the ofifen- sive odors, but do not destroy them. The ordinary offensive odors are due to hydric sulphide (HjS), ammonium sulphydrate (NS4HS), phosphorous hydride (PH3), and complex ammonium compounds. Chlorine, ozone, and nitrous oxides will destroy these gases by oxidation, and thus destroy the odor. It should be remembered that these odors, in themselves, may not be in any degree injurious to health, when in small quantity, but they serve to warn us of the presence of other products of putrefaction which accompany them, and which are injurious. The fact that efiScient disinfection of the air can prevent the spread of the contagion of disease is well known. Chlorine and sulphurous oxide are the two agents most in use, and of these the former is very much to be preferred, but the latter is used for furnished rooms, because of its less de- structive action on articles exposed to it. It is doubtful whether organized germs can be destroyed in the air by any disinfectants, except in tightly closed rooms. The attempt to disinfect the air of rooms with the various so-called " disinfectants " of the market is ivorse than useless. It engenders a feeling of security where there is none. These floating germs can certainly stand as much, and in most cases, more than man, and therefore, no room can be disinfected while it is occupied by human beings. The author has found by experiment, that most of the ordinary antiseptics, when diffused through the air of an ordinary room, are almost without action on putrefactive bacteria, unless the quantity be great enough to make the air irrespirable. The following table shows the amount of water it is necessary to add to one part of the substance named, which barely permit's the development of bacteria in meat infusions, according to M. Jalan de la Croix : — ~" Water, Parts. S.734 7,534 7.535 7.677 8,358 13,092 16,782 20,020 20,875 34,509 Water, I Part. Parts. I Part. Alcohol 30 Oil of mustard Chloroform •34 Sulphurous acid Borax 107 Aluminium acetate Eucalyptol 308 Salicylic acid Phenol (Carbolic acid) 1,002 Mercuric chloride Thymol 2,229 Calcium hypochlorite Potass, permanganate 3.041 Sulphuric acid Picric acid 3.041 Iodine Borated sodium salicylate 3.377 Bromine Benzoic acid 4,020 Chlorine NITROGEN AND HYDROGEN. i6s Devaine says of iodine, that i part to 12,000 destroys the con- tagion of charbon, and i to 10,000 of septrc blood. Billroth says mercuric chloride i to 20,000, thymol and benzoate of so- dium I to 2000, and benzoic acid and creasote i to 1000, pre- vent the development of bacteria. Koch says of mercuric chloride, i to 15,000 kills most micro-organisms, and i to 1000 destroys resting spores. The results of different experimenters are so widely discordant, that we make no attempt to reconcile them. The following table represents the results of experiments with commercial dis- infectants. The first column gives the per cent, of the agent necessary to kill anthrax and bacillus subtilis. The second gives the per cent, of the agent which failed to produce this result: — List of Commercial Disinfectants [Sternberg). NAME. Per cent, in, when active in two hours. Per cent, in, which failed in two hours. Little's Soluble Phenyle, Labarraque's Solution (U. S. P.), . . . Liquor Zinci Chloridi (Squibbs), . . . Feuchtwagner's Disinfectant, . Labarraque's Sol. (Frer^, Paris), . Phenol Sodique, Piatt's Chlorides, Gerondin Disinfectant, Williamson's Sanitary Fluid, 2 7 10 10 15 IS 20 25 25 25 30 0.25 I 5 7 8 10 10 15 15 20 20 Blackman's Disinfectant, Squibb's Impure Carbolic Acid, . Bouchardat's Disinfectant, . ... Phenol Sodique (Paris), . . . 20 50 SO 5° 50 Hypochlorite of .Sodium or Calcium. Available Chlorine, 192. Nitrogen and Hydrogen. — Ammonia — Source. — From the decomposition of animal or vegetable matter contain- ing nitrogen, either spontaneously or by the aid of heat. First prepared by distilling camel's dung, in Libya, near the temple of Jupiter Ammon. When horns, clippings of hides, or coal are heated in closed retorts, ammonia is given off. The principal source, at present, is from the ammoniacal liquors of gas works. Coal contains about 2 per cent, of nitrogen, which is mostly given l66 MEDICAL CHEMISTRY. off as ammonia. The ammonia liquor is treated with hydro- chloric acid, and evaporated to dryness, when an impure ammonium chloride, sal-ammoniac, is obtained. This may be purified by recrystallization or sublimation. This salt, heated with lime (CaO) gives off its ammonia. This is conducted through a series of Woulfe bottles containing water, in which the gas dissolves, forming aqua ammonia, from which the other compounds may be prepared. 2NH4CI + CaO = 2NH3 + Hfi + CaClj. 193. Properties. — Ammonia is a colorless, transparent, pungent, irrespirable gas. Does not support combustion or burn in air, but burns with difficulty in an atmosphere of oxygen, forming water and free nitrogen. It has a strong alkaline reaction on moistened litmus paper, which, however, is not permanent, ' owing to the volatility of the ammonia. It is lighter than air. Liquefies at — 40° C. ( — 40° F.) ; or at 10° C. (50° F.), under a pressure of 6.5 atmospheres, to a colorless liquid of specific gravity 0.76, which solidifies at — 75° C. ( - 103° F.). It is very soluble in water; one volume of water at 15° C. CS9° F.) dissolves 783 volumes of the gas with the evolution of heat, forming the solution known as aqua ammoniae, which may be regarded as a solution of ammonium hydroxide, NH^- 0-H in waier. This solution, on being heated, gives up most of the gas again. Aqua ammoniae fortior (U. S. P.) contains 28 per cent., by weight, of the gas, and has a sp. gr. of 0.901 at 15° C. (59° F.). Aqua ammoniae (U. S. P.) contains 10 per cent, by weight, and has a sp. gr. of 0.960 at 15° C. (59° F.). It is a colorless, transparent liquid, with a pungent odor, and alkaline taste and reaction. It forms, by direct union with the acids, a series of salts containing the compound radicle NH^, called ammonium (see Art. 345 e/ seq). Ammonia is volatile, and hence it is sometimes known as the volatile alkali. The compounds of NH4 closely resemble those of Na and K, and will be considered with them. The strong solutions of the gas act as a caustic upon animal tissues, and are, therefore, corrosive poisons. 194. Composition. — This may be determined by decom- posing the gas by passing a series of electric sparks through a quantity of it enclosed in an eudiometer tube over mercury. The volume increases until double the original volume is reached. By introducing a quantity of oxygen equal to ^ that of the am- NITROGEN AND CHLORINE. 1 67 monia used, and igniting tiie gases by the same spark, the hy- drogen and oxygen combine, and after condensing leave the nitrogen, which occupies one- half the original volume, or one- fourth the volume of the mixed hydrogen and nitrogen after the decomposition. It is thus shown to be composed of one-fourth nitrogen and three-fourths hydrogen. We may also arrive at the same result in the following manner: — Prepare a glass tube of about i c. t. ("^ in.) calibre, closed at one end ; through ihe stepper in the open end pass a funnel tube drawn to a point and provided with a slop-cock. Fill the tube with pure dry chlorine, and insert the cork. Fill the funnel tube with strong ammonium hydroxide solution, open the stop-cock, and allow a portion of the liquid to enter the tube. The chlorine decomposes the ammonia gas, combining with its own volume of hydrogen and setting free the nitrogen in combination with it. By removing the stopper under water, the latter will rise to fill the tube, excepting that por- tion occupied by the nitrogen, which will be found to be one-third of the whole tube. Now, as the chlorine combined with its own volume of hydro- gen, or with the tube full, and left one-third of that volume of nitrogen, it is easy to see that the ammonia was composed of three parts by volume of hydrogen, and one part of nitrogen. Since gaseous molecules all occupy the same space, three mole- cules of hydrogen and one of nitrogen form two of ammonia : 3H, .-I- N, = 2NII3. The compounds of ammonium with acids, will be considered under the head of salts of the alkaline metals. The compound, or derived ammonias, will be considered in part IV. Tests. — Odor. Fumes with HCl. Moistened red litmus paper is changed to blue by it. For Nessler's test, see Art. 146. 195. Nitrogen Chloride (NCI3). — When chlorine in ex- cess, is made to act upon ammonia, or a solution of ammonium chloride, the chlorine at first sets free nitrogen, and forms some ammonium chloride; the excess of chlorine then acts upon the ammonium chloride, to form nitrogen chloride. NH^Cl + sClj = NCI3 -I- 4HCI. Properties. — A yellow, oily liquid, insoluble in water, pos- sessing a disagreeable, irritating odor. Sp. gr. ^1.653. It is very explosive, and, in contact with any combustible matter, explodes spontaneously. It should not be prepared in large quantities. 1 68 MEDICAL CHEMISTRY. 196. Nitrogen Iodide (NHI, or Nh). Preparation.— By lightly triturating iodine in a mortar with strong ammonium hydroxide, or by pouring an alcoholic solution of iodine into strong ammonia water. Properties, — A brownish-black solid, insoluble in water; when spread out on filter paper and dried, it explodes with the slightest touch, or by a gentle breeze ; the explosion, however, is not nearly so violent as that of the chlorine compound. 197. Nitrogen and Oxygen. — Five oxides of nitrogen are known, whose names, graphic formulae, and corresponding acids are as follows : — Nitrous Oxide, . ... N— O— N Hyponitrous Acid, H— O— N Nitric Oxide OzZti N" O _ Nitrous Anhydride, . . Q— N— O— N3O Nitrous Acid, . H— O— N_0 "•"otT^fr'Sxi^^;}- • {8=N-0-N=0 ''"oi'^A'^nhTdridl;} • • • • {8=N-0-N=8 Citric Acid, . H-0-N=8 198. Nitrous Oxide. Hyponitrous Oxide, Laughing- gas. Nitrogen Monoxide. Nitrogen Protoxide (NjO). — Discovered in 1776, by Priestly. Anaesthetic effect first dis- covered by Sir Humphrey Davy. First used in dentistry by Wells, of Hartford, Ct. First came into notice as an ansesthetic in 1863. Preparation. — By gently heating ammonium nitrate in a retort similar to that represented in Fig. 41, when it decom- poses into nitrous oxide and water. NH4NO3 = NjO -I- 2Up. When prepared for ansesthetic purposes, care should be exer- cised to keep the temperature of the retort between 210° C. (^410° F.) and 250° C. (482° F.), as below the former the decom- position does not take place, but the salt sublimes ; while above the latter nitrogen dioxide and trioxide are generated. As an additional safeguard, the gas should be caused to bubble through solutions of sodium hydroxide and ferrous sulphate, to remove these higher oxides. Properties. — A colorless, odorless, sweetish-tasting gas, slightly soluble in water, more so in alcohol. Density 22. Sp. gr. 1.527. Under a pressure of 50 atmospheres at 7° C. (45° F.) it condenses to a colorless liquid, which resumes the gaseous state as soon as the pressure is removed, the temperature sinking so low as to freeze a portion of the liquid into a white, snow-like solid. Sp. gr. of liquid 0.908. Boiling point — 88° C. ( — 126° NITROGEN AND OXYGEN. 169 F.). Freezing point about — ioi° C. ( — 150° F.)- It is neutral in reaction, i. e., neither acid nor alkaline. It supports the combustion of bodies very much like oxygen ; this is due to the fact that the heat of the burning bodies decomposes the gas, giving an atmosphere about them containing twice as much oxygen as ordinary air. For anaesthetic purposes, the liquefied gas is now sold in wrought-iron cylinders, provided with a stop- cock, so that the gas can be drawn from the cylinder as needed. 199. Physiological Effects. — Nitrous oxide causes, when first inhaled, an exhilaration, then anjesthesia, and finally, as- phyxia. It will not support the respiration of plants or animals. It seems to act partly by excluding air, and partly by its direct effect upon the nervous system. It does not enter into any chemi- cal combination in the blood, but simply dissolves in this fluid. When mixed with oxygen, and administered under an increased pressure, the anaesthesia may be kept up for a long time with safety. Deaths from its inhalation are rare. It does not undergo decomposition in the blood. It is much used for short operations, and especially for the extraction of teeth, opening abscesses, felons, etc. Recovery is prompt and complete within a few minutes after its withdrawal. A solution in water containing five volumes of the gas, has been administered internally. 200. Hyponitrous Acid (HNO). — This acid may be pre- pared by the action of hydrochloric acid on the silver salt. AgNO -f- HCl = AgCl +• HNO. The potassium salt (KON) is formed by the action of sodium amalgam on potassium nitrite or nitrate ; preferably the former : KONO -I- 2H2 = KON -I- 2H2O. The silver salt is a yellow, almost insoluble powder. 201. Nitric Oxide or Nitrogen Dioxide. NO or N^Oj. — Prepared by the action of nitric acid upon copper. 3Cu -f 8HNO3 = 3Cu(N03)j + N2O2 -I- 4H,0. Properties. — A colorless, transparent gas, very sparingly soluble in water, more soluble in alcohol. Density 15, sp. gr. 1.039. The density would make the molecular weight 30, and the formula NO, which is anomalous, as in this case nitrogen must be considered as a dyad. The ordinary laws of valence would make it NjOj- I' '^ probable that at lower temperatures this is the proper formula, and at the higher temperature dissociation takes place, NjOj splitting up into NO, as has been proven to occur in the case of N^O^. »5 I 70 MEDICAL CHEMISTRY. By cold and pressure, the gas has been reduced to a liquid. Bodies which evolve considerable heat in burning, as phos- phorus, for example, burn in this gas, first decomposing it, and then uniting with its oxygen. In contact with free oxygen, or air, it takes up this gas and is converted into N^Oj, or N2O3, ac- cording to the amount of oxygen present. In both cases it gives a reddish-brown colored gas. The gas may be used as a test for free oxygen. It is rapidly absorbed by a solution of ferrous sul- phate, to which it imparts a deep brown color. Its action on the economy is not known. It forms no corresponding acid. 202. Nitrous Anhydride (N2O3). — Prepared by the direct union of nitric oxide (NO) and oxygen, mixed in the proportion of four of the former to one of the latter. Also, by warming nitric acid with starch, or arsenious acid, and by the action of the peroxide on cold water. 2N,0i -f H,0 = Nfi, + 2HNO3. Properties. — A dark blue liquid, boiling at 0° C. (32° F.), with partial decomposition, into N^Oj and N2O4 which recom- bine on cooling. It combines directly with water, producing nitrous acid (HNO2), which on warming, decomposes into nitric acid and nitric oxide. 3HNO2 = HNO3 + NA + Hp. As will be seen from the above, this oxide is very unstable. 203. Nitrous Acid and Nitrites. — The acid is not known in a pure state, but it exists in solution, and several of its salts are known. Thenitrites are formed by heating the nitrates, when they give off a part of their oxygen. The action is rendered easier, if lead or some other oxidizable metal be added to the fusion, 'rhe nitrites are produced in natiire by the oxidation of nitrogenous organic matter, accompanied by certain forms of microscopic life. Such nitrification takes place in waters polluted with organic mat- ter, and normally in the soil. The acid then combines with bases found in the water or soil. The presence of nitrites in water, is, for this reason, looked upon as an evidence of previous contami- nation with nitrogenous organic matter. Further oxidation leads to the formation of nitrates in the same circumstances. The addition of a dilute mineral acid to a nitrite, sets free reddish- brown fumes. A solution of argentic nitrate forms a precipitate with cold, not too dilute, solutions of an alkaline nitrite. These two reactions distinguish these salts from the nitrates. The reddish fumes, above mentioned, are strong oxidizing agents. NITROGEN AND OXYGEN. 171 and set free iodine fron potassium iodide. A solution of starch with which iodine forms a deep blue color, and a solution of potassium iodide with dilute sulphuric acid, are used as a test for nitrites in solution. Nitrous acid and the nitrites act as reducing agents upon an acid solution of potassium permanganate, and decolorize this latter salt. The nitrites can be taken up by plants, and elaborated into their structure, and hence are valuable fertilizers. 204. Nitrogen Peroxide, Nitrogen Tetroxide, Nitro- gen Dioxide (NjOj).^ — It may be prepared by mixing equal volumes of nitric oxide and oxygen. More easily, by heating dry plumbic nitrate in a retort, passing the vapors into a cooled receiver, where they condense into a liquid : — Pb(N03), = PbO + N,0,. Composition.— N20^ appears to exist in a pure state only at temperatures below 0° C. (32° F.). The liquid is colorless at these temperatures, but at its boiling point is yellow in color, owing to partial dissociation into NOj, which is complete at about 150° C. (302° F.). The gas is always reddish-brown :n color, due to the presence of NO.^, while NjO^ is colorless. The density of the gas at 26° C. (78.8° F.) (the boil- ing point of the liquid), is 38, and contains 20 per cent, of NO^. On raising the temperature, the density diminishes and finally becomes constant at 150° C. (302° F.), and equals 23. This density corresponds to NOj = 46. This phe- nomena of dissociation is frequently noticed in determining the density of bodies at temperatures much above their boiling points. The laws of equiv- alence seem to hold, in these cases, only at the. lower temperatures, at which dissociation does not take place ; hence, the confusion that exists in the formulae of such bodies as NjOj or NO3, NjOj or NO, Hg^Cl^ or HgCl, etc. Properties. — Cold water, in small quantity, decomposes it into N2O3 and HNO3, while in larger quantities and with alka- line hydroxides, it forms nitrous and nitric acids, or their salts. The tetroxide, N2O4, and the dioxide NO^, both act as strong oxidizing agents, settmg iodine free from the iodides. 205. Nitric Anhydride and Acid. — N2O5 and HNO3. Nitric Anhydride is a white crystalline solid, fusing at 30° C. (86° F.), and boiling at 47°C. (116.6° F.). Obtained by treat- ing dry silver nitrate with chlorine, or by the removal of water from fuming nitric acid by the action of phosphoric anhydride (P2O5). The oxide is unstable, and has a strong affinity for water with which it forms nitric acid. It has no special use. I 72 MEDICAL CHEMISTRY. 206. Nitric Acid— Aqua Fortis,— Acidum Nitricum, U. S. P. (.HNO3), is the most important of the acids of nilrogtn. It does not occur free, but as nitrates widely disseminated. It is usually prepared, commercially, by the action of sulphuric acid upon potassium or sodium nitrate, in glass or cast iron retorts. NaNOa + HjSO^ = HNaSO^ + HNO3. The arrangement of the iron retorts (A) and the stoneware condensers (B) are shown in section in Fig. 50. The sodium nitrate and an equal weight of sulphuric acid is run in through the stoppered openings at the back. The iron is protected from the acid by a lining of fire clay. When heat is applied to the retort the nitric acid distils over and condenses in the stoneware Woulfe bottle B, which is kept cooled by cold water. Fig. 50. It is also formed in small quantities by the passage of electric discharges through a mixture of nitrogen and oxygen. This takes place in the air by the passage of flashes of lightning, probably by the oxidizing action of the ozone generated by these phenomena. The nitrates are formed in the soil and natural waters by the oxidation of organic matter, called nitrification, and is induced by certain microscopic organisms called the nitri- fying ferment. In some localities the process is conducted arti- ficially. (See Potassium Nitrate.) The commercial acid, prepared as above, contains sulphuric acid, traces of iron, the brown oxides and chlorine. It is purified by redistillation with plumbic nitrate, which retains the impurities and allows the pure acid to distil over. NITROGEN AND OXYGEN. 1/3 Properties. — The pure acid is a colorless, rather heavy, fuming liquid, having asp. gr. of 1.52, boiling at 86° C. (186.8° F.), and solidifying at — 40° C. ( — 40° F.). The sp. gr. and boiling-point of the diluted acid vary with the proportion of acid present. When strongly heated, or on exposure to light and air, the acid turns yellow and is decomposed into nitric tetroxide (N2O4), water, and oxygen. Nitric acid readily gives up a portion of its oxygen, and thus acts as a strong oxidizing agent, attacking and destroying vege- table and animal tissues and coloring matters. It is sometimes used as a cauterizing agent, first producing a yellow stain, then destroying the tissue. While it oxidizes most organic bodies, it enters into the composition of others, forming substitution pro- ducts. Thus glycerin, cotton, sugar, etc., when treated with it form explosive substitution products. Most metals dissolve in the acid, forming nitrates ; gold and platinum are exceptions. The non-metals or negative elements are usually oxidized by it. Metallic iron dissolves readily in the dilute, but when plunged into strong acid, it assumes a condition known as the passive state; if now it be put into dilute acid, it is not attacked by. it until a piece of platinum is brought into contact with it, or by some other means the passive condition is destroyed. Nitroso- nitric acid is a yellow, partially decomposed acid, containing nitric peroxide (NjOi). Aqua regia is prepared by mixing together four parts of hydrochloric, and one of nitric acid ; it soon 9.ssumes a yellowish-red color, and has the power to dissolve gold, platinum and other metals, with the formation of chlorides. Fuming Nitric Acid. — ^A reddish-brown acid. Sp. gr. 1.525. Containing N^Os or N2O4. Used as a powerful oxidiz- ing agent. 207. Official Forms. — Acidum Nitricum. — Sp. gr. 1.414 contains 68 per cent, of HNO3. Acidum Nitricum Dilutum is prepared by adding 5.8 parts of distilled water to one of the above acid. Sp. gr. 1.057, and contains 10 per cent, of HNO3. Used for internal admin- istration. Dose tii,5 to 15. 208. Tests. — I. Add to suspected liquid some ferrous sul- phate, and pour the mixture on some strong sulphuric acid in a test tube. A black, brown, or reddish zone at the point of con- tact of the two liquids indicates nitric acid. (See Art. 201.) 2. Heat the suspected solution with some sulphuric acid faintly colored with indigo, when, if nitric acid or a nitrate be present, the blue color will disappear. 174 MEDICAL CHEMISTRY. 3. The strong acid imparts a deep red color to the alkaloid brucine. 4. When heated with copper turnings, the liquid assumes a green color, and evolves reddish fumes. When the acid is in combination, a stronger acid must be added to set it free, as in test 2. 209. Physiological Effects. — In small quantities, well di- luted, it is a stomachic tonic, and augments the secretion of urine. It seems to be mostly decomposed in the body, but a small quantity may pass into the urine as nitrates; it acts, therefore, as an oxidizing agent. The strong acid is a corrosive, violent poison, first staining the tissues and vomit with which it comes in contact a bright yellow color, and then corroding them. These stains will be found on the tongue and faiices in cases of poison- ing by this acid. Antidote — milk of lime, magnesia, or other alkalies well diluted, followed by sustaining treatment. PHOSPHORUS. Density of vapor ^ 62. Mol. wt. 124. = P^. At very high tempera- tures D = 31 and Mol. wt. = 62 = Pj. 210. Occurrence. — Discovered by Brandt, in 1669, in urine; and by Gahn, in bones, in 1769. Does not occur native, but as phosphates and in organic substances. Most com- mon mineral is calcium phosphate, Ca3(P04)2, derived from bones of prehistoric mammals. Preparation. — Phosphorus is usually prepared from the ash of burnt bones, in which it exists as tri-calcium phosphate Ca3(P04)2. The ash, by treating it with sulphuric acid, is first converted into a soluble monocalcium phosphate, sometimes called superphosphate. Cb,{?0^)., + 2H2SO4 = CaH4(POj2 + 2CaS04. The CaH4(P04)2 is dissolved in water, and drawn off, leaving the CaSOji in the vat. This solution is evaporated to dryness, after adding powdered charcoal and sand, and then transferred to a retort, whose beak dips under water. The retorts are then gradually heated to a high temperature, when the Ci3Llli(P0i).i, is first dehydrated and converted into calcium metaphosphate, Ca- (P03)2 and water, and then undergoes reduction under the action of the carbon and sand as follows : — PHOSPHORUS. 175 CaH.(PO,), = Ca(P03), + 2H,0. 2Ca(P03)2 + 2Si0a + loC = 2CaSi03 + loCO + P^. The free phosphorus distils over and condenses under the water as an impure article, which is purified by redistillation, or by fusing it under water with sulphuric acid and potassium di- chromate. It is then cast into sticks, in moulds. 211. Properties — Physical. — Phosphorus is met with in several distinct allotropic states. The ordinary form is a translucent, waxy-looking solid, which, at ordinary temperatures, is tenacious, and about the consistency of wax ; but at 0° C. (32° F.) and below, it becomes brittle. It melts at 44° C. (iii°F.) under waterj and boils at 290° C. (554° F.). By the action of light, it soon becomes coated with a whitish or reddish layer, probably an oxide. The sp. gr. is 1.83 at 10° C. (50° F.). It shines in the dark, and when exposed to moist air, emits the odor of ozone. It is insoluble in water and alcohol, but soluble in ether, benzene, petroleum, and in the fixed and essential oils. The best solvent is carbon disulphide. From this solution it separates in the form of octahedral and dodecahedral crystals. When a portion of the solution is poured upon filter paper and allowed to evaporate spontaneously, it takes fire when the evaporation is complete. Red or Amorphous Phosphorus is a reddish-brown amor- phous powder, of sp. gr. 2.14, insoluble in carbon disulphide; it does not alter in the air, and does not show the phosphorescence in the dark. While ordinary phosphorus is very poisonous, even to workmen handling it, this variety is entirely harmless. When heated to 260° C. (500° F.), it does not melt, but gradually sub- limes. The vapor is converted into the ordinary form, which takes fire in presence of air. Red phosphorus is prepared by heating the ordinary variety for about thirty-six hours, to a temperature of from 250° C. (482° F.) to 300° C. (572° F.) in an atmosphere of hydrogen, carbon dioxide, or in an exhausted iron vessel. The mass is then washed with carbon disulphide, to remove any of the ordinary variety remaining. Other varieties of phosphorus have been formed. The me- tallic form, by heating the red variety in a sealed tube, to 500° C. (986° F.) when black, metallic-looking, microscopic needles sublime into the cooler portions of the tube. The sp. gr. of this variety is 2.34, and it is less active than the red variety. Chemical Properties. — Tne most characteristic property of phosphorus is its ready oxidation. If the ordinary variety be 176 MEDICAL CHEMISTRY. heated to 60° C. (140° F.) in contact with air, it takes fire and burns with a brilliant flame, and evolves a voluminous white cloud of phosphoric pentoxide. It may be burned under warm water, by throwing a jet of oxygen upon it. It must be kept under water to prevent it from taking fire spontaneously. When fragments, partly covered with water, are exposed to the air, white fumes are seen to arise from them, which contain ozone, hydric peroxide, and possibly ammonium nitrite (NH^NOj). This ozone is the cause of the odor usually detected when phosphorus is exposed to the air. The red variety does not oxidize in the air, and may be handled with impunity. Phosphorus unites readily with fluorine, chlorine, bromine and iodine, forming, in each case, two compounds of the general formula PR, and PR5, except in the case of iodine, which forms PI2 and PI3. An oxychloride of phosphorus (POCi) is also known. It combines with most other elements excepting carbon, nitrogen and hydrogen. It -reduces some metallic salts, as copper and silver, to the metallic state. 212. Tests. — Its phosphorescence in the dark, either as found, or after separating it with carbon disulphide and evapora- tion of the latter liquid. It imparts a green color to the hydrogen flame, when this gas is conducted through a solution containing it before being burned. 213. Physiological Action. — Owing to the ready inflam- mability of the ordmary variety, deep burns are liable to occur from careless handling, which are more serious and difficult to heal than burns from other combustibles. When taken inter- nally, phosphorus is a very poisonous substance. Cases of poisoning from " ratsbane" or " rat poison" containing it, are not infrequent. The symptoms of acute poisoning are, a garlicky odor and taste in the mouth, heat and burning in the stomach, vomiting of a dark-colored matter, which is phosphorescent, when shaken in the dark. Weak pulse, low temperature, cold extremities, dilated pupils, and a clear mind are usually seen. Death in from 2 to 12 days. Average about 3 to 4 days. These symptoms may make their appearance in an hour after the poison is taken, or after 3 or 4 days. Poisonous dose varies. Gr. -^^^ to \ has produced death. Antidotes. There is no chemical antidote. Emetics, or the stomach pump are the best early treatment; then, mucilaginous drinks., with lime or magnesia, or oil of turpentine. The old oil is best; but no other oils should be given, as they dissolve the phosphorus and favor absorption. Recovery is rare. PHOSPHORUS. 177 Chronic poisoning of workmen in match factories frequently occurs ; the symptoms are fatigue, pains in stomach and bowels, with diarrhoea, carious teeth, swollen and inflamed gums, and finally necrosis of the jaws, usually the lower. Fatty degenera- tion of the liver, kidneys, heart and other muscles, and destruc- tion of the red corpuscles, are also noticed. These evils are now remedied by using red phosphorus in making matches, as it is not poisonous. 214. Official Preparations: — Oleum Phosphoratum. — A I per cent, solution of phosphorus in sweet almond oil. Pilulae Phosphori. — These pills contain 0.0006 gm. (^hi grain) of phosphorus each, and are coated with balsam of tolu. Spiritus Phosphori. — Spirit or Tincture of Phosphorus. This is a solution of phosphorus in absolute alcohol, made by distillation, and containing 1.2 gm. in 1000 c.c. ; it is used for making Elixir Phosphori. 215. Phosphorus and Hydrogen— Phosphoretted Hydrogen. — Phosphine. — There are three hydrides of phos- phorus known, which are all formed together by boiling phos- phorus with strong potash or soda lye, or with milk of lime. They appear as a gaseous mixture, which takes fire spontaneously on coming to the air. When the beak of the retort in which it is prepared dips under water, a precaution always to be taken, each bubble ignites on coming to the surface, producing beauti- ful white rings of P2O5. This inflammable gas, composed mostly of PH3, is found on examination to contain also a liquid com- pound (P2H4), which is highly inflammable on exposure to air, while the gas (PH3) is not. This yellow volatile liquid, on stand- ing in sunlight, deposits a yellow solid (P^Hj). Phosphine (PH3) is colorless, sparingly soluble in water, and has a strong alliaceous odor. The impure gas is formed during the putrefactive decomposi- tion of organic substances containing phosphorus, especially under water, and takes fire spontaneously on rising to the surface, producing the ignis fatuus or " Will o' the wisp " sometimes seen in marshy places. The gas is very poisonous, even in small quantities. The blood, after deaths caused by it, is found to be dark colored* with a violet tinge, and has lost the power of ab- sorbing oxygen. It 'poisons, therefore, by its reducing action on the blood. Its density is 17, and its sp. gr. 1.134. Phosphine resembles, in some respects, the corresponding compound of nitrogen (NH3). It unites directly with HBr and HI, to form phosphonium bromide (PH^Br), and iodide 16 178 MEDICAL CHEMISTRY. (PHJ), corresponding with the ammonium compounds, NH^Br and NH4I. 216. Phosphorus and the Halogens. — Phosphorus forms three compounds with chlorine. Phosphorus trichloride, PCIs, is a colorless fuming liquid, boiling at 70° C. (165 2 F), sp. gr. 1. 61, and prepared by direct union of the elements. It is much used as a reagent in organic chemistry. Phosphorus Pentachloride (PCI5), is a yellowish-white, crystalline solid fuming in the air, and subliming without fusion when heated. Prepared by treating PCI3 with excess of chlorine, and used as a reagent in organic chemistry. Phosphorus Oxychloride (POCI3), is formed by the action of a limited quantity of water on the pentachloride. It is a colorless liquid with a pungent odor, and a sp. gr. of 1.7. Boils at 110° C. (230° F.) Phosphorus unites directly with bromine, giving a tribromide and pentabromide, and with iodine, giving two crystalline solid compounds, PI3 and P2I4, and with fluorine PF3 and PF5. These latter compounds, as well as those of phosphorus with sulphur, of which there are six known, are of no interest to the medical student. 217. Phosphorus and Oxygen. — The following oxides and acids are known : — P4O Phosphorus suboxide. I'jO , P — O — P Phosphorus monoxide -)- 3HjO = 2H3PO2. Hypopbos- pborous acid. PjOj , 0=P — O — P = O Phosphorus trioxide + sH^O = 2H3PO3 Phos- phorous acid. P2O4 , o^P — P*^o f ^°5P^°™s tetroxide. Q^p — o'— P\o Plj<"=plJo™spentoxide + 3H,0 = 2H,P04 Ortbophosphoric acid. +2Hp=H4Pp, Pyrophospboric acid. + H,0 == 2HP0s Metaphosphoric acid. 218. Phosphorous Oxide, Phosphorus Trioxide (P2O3). This compound is formed by the slow oxidation of phosphorus m dry air. When dissolved in water it forms phosphorous acid, H— O— p=0 H— O— ^— H. PjOs + 3HjO= 2H3PO3 or 2HJPHO3. Phosphorous Acid is a colorless liquid, which is easily oxidized to phosphoric acid by absorbing oxygen from the air. It is a dibasic acid. Its salts are known as phosphites. PHOSPHORUS. 1 79 NajPHOj Phosphite of sodium. KjPHOj Phosphite of potassium. Tests. — I. With HgClj it gives a white ppt. consisting of Hg.,CI,. 2. With AgNOs it gives a black ppt. of metallic silver. 219. Phosphoric Oxide, Phosphorus Pentoxide (P2O5). — This is formed by the rapid burning of phosphorus in the air, and rises as a voluminous white cloud. It has a powerful afiRnity for water, with which it combines with a hissing noise, forming metaphosphoric acid ; this when heated with more water is con- verted into the orthophosphoric acid. Tfi, + H,0 = 2HPO3. 2HPO3 + 2H2O = 2H3PO,. 220. Orthophosphoric Acid, or Common Phosphoric Acid (HsPOi) is the most important acid of phosphorus. It is readily prepared by boiling phosphorus with dilute nitric acid, and evaporating the solution to a syrupy consistency. A very strong nitric acid should not be used, because the oxi- dation would then be so rapid that an explosion might occur. 3?, + 10HNO3 + 4H,0 = 6H3PO, + sN.Oj. It may also be made by decomposing phosphates with sulphuric acid. It is a tribasic acid forming three series of salts, namely : 1. Normal salts. NajPOj Trisodium phosphate. Ca3(POj)2 Tricalcium phosphate. 2. Acid salts. . fNa^HPOj Disodium hydrogen phosphate tCajHj(POj) Dicalcium-hydrogen phosphate. Tj / NaHjPO^ Sodium- dihydrogen phosphate \CaHj(P04)2 Mono-calcium-tetrahydrogen phosphate. 3. Double salts. NHjNgPOj Amraonio-magnesium phosphate. KBaPOj Potassio-barium phosphate. Acidum Phosphoric um U. S. P., is a colorless, odorless, non-fuming, strongly acid liquid, containing not less than 85 per cent, of absolute phosphoric acid. Sp. gr. 1.710 at 15° C. (S9° F.). It is miscible in all proportions with water and alcohol. l8o MEDICAL CHEMISTRY. When heated to 200° C. (392° F.) it loses water, and is gradually converted into pyrophosphorie acid. At a higher tem- perature it is converted into metaphosphoric acid, which volatil- izes in dense fumes, which condense into a transparent mass called glacial phosphoric acid. 2H3PO4 — HjO = HjPPj Pyrophosphorie acid. 2H3PO4 — 2H2O ^= 2HPO3 Glacial or metaphosphoric acid. Acidum Phosphoricum Dilutum, U. S. P., contains 10 per cent, of absolute H3PO4. Sp. gr. is 1057 at 150° C. (59° R). 221. Tests: 1. Add a slight excess of NHjOH, then a solution of NH^CI, and some MgSOi solution, and a white crystalline ppt. of am- monio-magnesium phosphate is produced. U^VO^ + MgSO, + 3NH,0H= NH.MgPO^ + (NHJ.SO^ + sH^O. 2. If this ppt. be dissolved in dilute acetic acid, and a solu- tion of AgNOa added, a yellow ppt. of silver phosphate is pro- duced. 3. If a solution of ammonium raolybdate in dilute HNO3 be added to phosphoric acid or a phosphate, and heat applied, a yellow ppt. of phospho-molybdate of ammonium is produced. The ppt. is readily soluble in ammonia water. This is a very delicate test. 222. Pyrophosphorie Acid. — When phosphoric acid is heated to about 200° C. (392° F.), two molecules lose one mole- cule of water, and then unite to form a doubly condensed molecule, which is called pyrophosphorie acid. This is a tetra- basic acid, H4P2O7, and forms salts called pyrophosphates. Sodium pyrophosphate has the formula NaiP-^O,. Tests. — I. It gives a white ppt. witla ammonio-nitrate of silver. The ortho-acid gives a yellow ppt. 2. It is not pptd. by ammonium molybdate, and does not coagulate altumin. 223. Metaphosphoric Acid, HPO3 (Glacial Phosphoric Acid).^-When the pyrophosphorie acid, is heated almost to redness, metaphosphoric acid is produced, as a white, glassy, colorless solid. It is usually prepared by heating ammonium phosphate to a red heat. Metaphosphoric acid is monobasic, and forms salts called metaphosphates. NaPOj is metaphosphate of sodium. Tests. — I. It gives a white ppt. with ammonio-nitrate of silver. PHOSPHORUS. l8l 2. It coagulates albumin, while pyro- and ortho-phosphoric acids do not. 3- It is not pptd. by MgSOi in the presence of NHiOH and NH4CI as the ortho- acid is. Meta- and pyrophosphoric acids and their salts, when taken internally, are said to have a decided inhibitory action upon the motor ganglia of the heart, and may even cause its cessation and death when given in too large quantities. 224. Hypophosphorous Acid (H3PO2). — When ordinary phosphorus is boiled with a solution of sodium, potassium, ba- rium, or calcium hydroxide, phosphorus^ hydride escapes, and there is formed in solution a hypophosphite of the metal present. From the barium salt the acid may be prepared by treatment with enough dilute sulphuric acid to precipitate the barium as sulphate. The filtered solution is then to be concentrated under the air pump, as heat decomposes it. The acid thus prepared, is a colorless, syrupy, strongly acid liquid ; it is unstable in the air, gradually changing into phosphorous and phosphoric acids. The acid is of little importance, but several of its salts are used in medicine. They are generally administered in the form of syrup. They have a strong reducing action on many metallic salts, and this should be remembered in prescribing them. Mercuric chloride is reduced to metallic mercury by the alkaline hypophosphites, and ferric to ferrous salts. 225. Acidum Hypophosphorosum Dilutum, U. S. P., is a colorless, odorless, liquid, miscible in all proportions with water. It should contain 10 per cent, of absolute hypophosphor- ous acid, H3PO2 or HPHA- Subjected to high temperatures, it breaks up into PH3 and H3PO4, the PH3 igniting in contact with the air. Tests. — I. Silver nitrate gives a black precipitate of metallic silver. 2. When gently heated with CuSO, solution, a yellow precipitate of hydride of copper falls, which rapidly turns reddish-brown. Hypophosphorous, as well as phosphorous acid, is peculiar in its compo- sition. While there are three atoms of hydrogen in the molecules of both acids, but one in the first and two in the second are basic, i. e., that can be replaced by a basic radical or metallic atom. In these two acids the phos- phorus is pentad, as in phosphoric acid; and in the former two non-basic hydrogen atoms are believed to be united directly to the phosphorus, while the basic hydrogen atom is linked to it by an oxygen atom, thus : — -O— H. °=PE5 r82 MEDICAL CHEMISTRY. ARSENIC. As = 75. 226. Occurrence. — Arsenic occurs native and in tiie form of arsenides, the sulphides, orpiment and realgar, and as arseni- cal pyrites or mispickel. Besides occurring in these minerals in considerable quantities, it is contained in small quantities in a great number of other minerals and even in organic sub- stances. The sulphides, and even the element, were known to the ancients. Preparation. — Usually obtained in the form of the oxide by calcining mispickel, and condensing the white volatilized AS2O3 ; this oxide is then strongly heated in a retort with char- coal to obtain the element, which distils over. Although this is the method most used, it may be obtained from other minerals containing it. Properties. — A brittle, steel-gray, crystalline solid, pos- sessing a metallic lustre, and a sp. gr. of 5.75. It also exists as an amorphous, lustreless, black mass, easily pulverized, and having a sp. gr. of 4.71. When heated out of contact with air, under ordinary pressures, it sublimes at 180° C. (356° F.) with- out previous fusion ; but under strong pressure it fuses. Its vapor has a yellow color and a density of 150 ; its molecular weight is, therefore, 300, and its molecular formula Asj. At a white heat its density is 75, and molecular formula Asj. In dry air it is permanent ; but when heated, it burns with a bluish flame, emitting the odor of garlic, and white fumes of arsenious oxide (AsuOs). It combines directly with many of the elements, both metallic and non-metallic, as chlorine, bromine, iodine, copper, iron, etc., yielding arsenides. The metallic arsenides resemble alloys. It combines readily with nascent hydrogen, which takes it from any of its compounds. Nitric and sulphuric acids are decomposed by it, without forming salts. It is oxidized by boiling solutions of caustic potash, forming potassium arsenue and arsenide. Arsenic is used in pyrotechny, in the manufacture of fly poison (under the name of cobalt), in shot and in certain pigments. 227. Arsenic and Hydrogen. — One arsenide of hydrogen is known, AsHj. Hydrogen Arsenide, Arseniuretted Hydrogen, or Arsine, AsH,, is of great practical interest to the toxicologist, as it enters into some of the most delicate tests for the detection ARSENIC. 183 of the element. It may be prepared by a number of reactions, the most common of which are the following: — ist. By decomposing the metallic arsenides with hydrochloric acid. 2d. By the action of nascent hydrogen upon arsenical com- pounds. This may be generated in the solution by the action of hot caustic potash solutions, or dilute sulphuric acid, upon metal- lic zinc. 3d. By the reducing action of moist organic matter upon compounds of arsenic. It is a colorless gas, with a strong garlic odor, combustible in air, burning with a bluish-white flame, and emitting white fumes of Asi O3 ; a cold surface pressed down upon this flame receives a black stain of arsenic. When passed through a tube heated to a dull-red heat, it is decomposed into hydrogen and arsenic, which last deposits in the cooler part of the tube as a metallic mirror. (See Marsh's Test.) The gas is readily decomposed by oxidizing agents, and the alkaline hydroxides. It is exceedingly poisonous. 228. Arsenic and the Halogen Elements. — Arsenic forms one compound with each of this group of elements, with the general formula As R3, in which R stands for a halogen atom. The tri-fluoride and the tri-chloride are liquids, the first boil- ing at 63° C. (145.4° F.) and the second at 134° C. (273° F.). They are formed when a fluoride or chloride is heated with arsenic trioxide and sulphuric acid. The tri-iodide and tri-bromide of arsenic are obtained by direct union of the elements. They are both solids. The tri- iodide is official, as Arseni lodidum, Asl,. It occurs as glossy, orange-red, crystalline masses or scales. It has an iodine- like odor, and gradually loses iodine upon exposure to light and air. It is soluble in about 7 parts of water, and in 30 parts of alcohol. The aqueous solution gradually decomposes into arsenious and hydriodic acids. It is used in the preparation of Liquor Arseni et Hydrargyri lodidi (Donovan's Solution) U. S. P. This solution contains one per cent, each of Asljand Hgl,. 229. Arsenic and Sulphur. — There are at least three well-known compounds of arsenic and sulphur, AsjSg, AsjSj and AS2S2. Arsenious sulphide (AsjS^) occurs native as orpiment, in the form of gold-yellow, crystalline masses. It may be pre- 184 MEDICAL CHEMISTRY. pared artificially by precipitating arsenious acid or its salts with hydric sulphide, or by heating sulphur and arsenious oxide (AsaOs). It is lemon-yellow in color, soluble in the alkaline hydroxides, and in yellow ammonium sulphide, but insoluble in water and dilute acids. Arsenic Pentasulphide (AsjSs) is also a bright yellow powder of no special interest. Arsenic Disulphide, (AsjSj), occurs native, as realgar, in the form of orange-red crystalline masses of sp. gr. 3.5. Realgar and orpiment are used as pigments. 230. Oxides and acids of Arsenic. — Arsenic forms two oxides with corresponding acids : — AsjO, H3ASO3 Arsenious Oxide, or Anhydride. Arsenious Acid. ASjOb H3ASO, Arsenic Oxide, or Anhydride. Arsenic Acid. 231. Arsenious Oxide (AsjOs) is the most important of the compounds of arsenic. It occurs in nature as arsenic " bloom." It is obtained artificially as a side product in roasting ores of other metals containing arsenic, when it volatilizes and is con- densed in large chambers as a white powder. It is purified by resublimation, in iron retorts, and is obtained in the form of a white powder or glassy-looking solid, of a sp. gr. of 3.69. Properties. — As ordinarily met with "white arsenic" is a white, somewhat gritty powder, which under the microscope, is seen to be made up of more or less regular octahedral crystals. When the vapor is rapidly cooled, the crystals take the form of rhombic prisms, and it is, therefore, dimorphous. When heated, it sublimes without fusing, at about 218° C. (424° F.). When heated in sealed tubes, it melts into a vitreous mass. The density of the vapor is 198, corresponding to the formula AsjOe which is probably the formula of the vitreous variety, while that of the octahedral variety is AS2O3. It is soluble with difficulty in water, forming a sweetish, metallic, and nauseous-tasting, poisonous solution of arsenious acid (q. v.). It is also soluble, with decomposition, in hydrochloric acid and alkaline solutions, the arsenic atoms playing the basic role in the former, and the acid role in the latter. Nascent hydrogen re- duces the oxide, and converts the arsenic into arsine (ASH3), while oxidizing agents convert it into arsenic acid. 232. Arsenious Acid (HaAsOj), is formed by dissolving AsjOs in water. A solution of the acid in dilute hydrochloric ARSENIC. 185 acid is official under the name of Liquor Acidi Arsenosi, containing i per cent, of AFjOg. It forms a series of salts called arsenates. Potassium arsenite is official as Fowler's solution, or Liq. Potass. Arsenitis. Scheele's green is an arsenite of copper, used as a pigment. Paris green is a mixture of acetate and arsenite of copper. 233. Arsenic Oxide (AfjOs), is a white, amorphous, deli- quebcent solid, dissolving in water to produce arsenic acid. AsjOj + 3HjO = 2H3ASO4. Arsenic acid is usually prepared by warming arsenious acid with nitric acid, when the AsjOs is oxidized at the expense of the nitric acid. On evaporating, the solution yields needle-shaped crystals of H3ASO4. The aqueous solution is strongly acid. On heating the crystals of arsenic acid, both the pyro-arsenic and meta-arsenic acids are produced, corresponding to the similar acids of phosphorus. But one salt of this acid is official. Sodium Arsenate, Na2HAs047H20, also a one per cent, solution of this salt. Liquor Sodii Arsenatis. 234. Arsenic Poisoning^Toxicology. — From the earliest history of arsenic, it has bten used as a poison for criminal purposes. While every physician should not undertake the analysis in cases of suspected poisoning by this agent, a knowledge of the outlines of the chemist's methods of analysis, etc., will teach the physician to prepare the way for the analyst. Moreover, a few preliminary tests by the physician may frequently save much unnecessary litigation and expense in suspected cases. Other reasons might be given why every physician should have some knowledge of toxicological science, that care may be taken to punish the guilty and. protect the innocent. The attending physician is often responsible for the connection of the links of evidence. All compounds of arsenic are poisonous, and the poison usually enters the system by the mouth, although it has been absorbed by the skin, mucous membranes, or abraded surfaces, in sufficient quantities to produce poisonous results, especially chronic poisoning. Colored wall paper, colored toys, confectionery, and certain anilin dyes used in fabrics, may give rise to accidental poisoning. 235. The Physician's duty in cases of Poisoning may be briefly stated as ioUows : In case foul play is suspected, do not fail to make careful notes, at the time, as to dates, symptoms and circumstances, or facts leading to suspicion. 1 86 MEDICAL CHEMISTRY. The physician should collect and preserve the urine, faeces, vomit, and the suspected vehicle of the poison, and place them under seal, or lock and key. He should test some one or all of these, to satisfy himself as to the truth or falsity of his suspi- cion. As little publicity as possible should be given to matters of fact or opinion at the time. Be not too ready to express your opinion upon the origin of the poison in cases of this kind, lest you jeopardize the reputation of your patient or others. Whether a fatal termination is expected or not, it is wise to take these precautions. In case of fatal termination, notify the prosecuting officer, or coroner, of your suspicion, and immediately request an autopsy; but remember that you are not released from your responsibility in the case by so doing, nor are you at liberty to tell all you know, until you are summoned to do so on the witness stand. Before you attend the autopsy, read carefully, and refresh your memory upon the directions for making post-mortem examina- tions, and on the post-mortem appearances in cases of poisoning,' whether you are to make the examination yourself or not. If possible, see that the chemist who is to make the analysis is pres- ent at the autopsy. (See Woodman and Tidy, " Forensic Med- icine.") The entire intestinal canal, at least one-half of the liver, the spleen, one kidney, the brain, and any urine remaining in the bladder, should be saved ; the brain and the entire intes- tinal canal, ligatured at both etids of the stomach and left un- opened, are to be preserved in separate jars, while the other organs may be placed in a separate jar. These jars must be new and clean, and closed with new corks or glass — not with metal caps. They are then to be closed with a seal, with some peculiar stamp upon it, so that they cannot be opened without detection. They must not be intrusted to a servant or any irresponsible per- son, but turned over as soon as possible to the chemist, or to the prosecuting officer or coroner. Notes to be admitted on the witness stand, must be the original ; not a copy of those taken at the time to which they refer. ^36. Symptoms of Arsenical Poisoning. — The symp- toms are those of an intense irritant. There is usually marked "fire-burning" pairt in the epigastrium, increased by pressure. Violent vomiting, tenesmus, burning pains at the anus, and pain- ful cramps in the legs are usually present. Intense thirst, dry, hot skin, severe headache, small, rapid pulse, anxious, pinched countenance, the eyes suffused and smarting, tongue dry and furred, photophobia, great restlessness, nervous twitchings, with ARSENIC. 187 a perfectly clear mind, are symptoms usually to be expected. The urine is diminished, with frequent and painful micturition. These symptoms may end in convulsions, tetanus, collapse, or coma and death. Mmimum fatal dose, from 1.5 to 2.5 grains. Chronic arsenical poisoning is usually attended by conjunctival inflammation, irritation of the skin with a vesicular, or nettle- rash eruption, similar to that of scarlet fever. Irritation of the stomach and bowels, exfoliation of the cuticle of skin and tongue, and falling of the hair, have been noticed. Local paralyses, preceded by numbness, or tingling of the toes and fingers, and marked nervous disorders, are of common occurrence. 237. Treatment. — Remove any unabsorbed poison from the stomach by emetics or with the stomach pump, or better, by thorough irrigation with the stomach tube. The best antidote is freshly precipitated ferric or magnesium hydroxide, or a solution of dialyzed iron. The solution of dialyzed iron, now found in the shops, may be used instead of the above, and may be given in teaspoonful doses at short intervals. This forms an insoluble compound with the arsenious acid, and thus prevents further absorption. There are two antidotes official, i. Freshly prepared ferric hydroxide. This is made by adding ammonia water to solution of ferric sulphate, thoroughly washing the precipitate with water to remove the ammonia, which is a strong caustic. 2. Ferri Oxidum Hydratum cutn Magnesia. It is directed that a solu- tion of ferric sulphate and a mixture of magnesia and water be kept on hand, and when wanted, the two poured together and shaken up. Ferric hydroxide and magnesium sulphate are formed. This mixture has the advantage of being free from ammonia, while the presence of magnesium sulphate is an additional advantage. The symptoms caused by the absorbed poison are to be treated as they arise. 238. Toxicology. — There have been devised a large number of tests for the detection and identification of arsenic. Some of these are easy of application, while others will be used only by the chemist. We can only give the outline of these tests, and leave the student to consult special works for details. The analysis after death, in cases of suspected poisoning, should not be undertaken by the physician, nor even by a chemist, unless he has a well-equipped laboratory, in which he can conduct the analysis from beginning to end, alone, and without interruption. During the life of the patient, the physician should be able to test the urine, faeces, suspected articles of diet, medicines, etc., for the presence or absence of arsenic. For this purpose l88 MEDICAL CHEMISTRY. lie may use Reinsch's or Marsh's test, but it must be understood that neither of these tests alone, when performed as about to be described, is to be relied upon as positively certain. Reinsch's test may be conducted as follows: — To a portion of the urine or other suspected liquid, add about one-sixth its volume of pure hydrochloric acid and some strips of pure copper foil, and boil the solution. If arsenic be present, a steel-gray or bluish deposit will be formed on the surface of the copper. This deposit is not positive proof, however, as antimony, bismuth and mercury may give similar deposits ; it is, therefore, necessary to apply tests to this deposit, in order to determine its identity. For this purpose the copper is removed, washed in water, dried between folds of filter paper, and placed in a clean, dry, wide test tube, and heated to a dull-red heat, taking care to heat only that portion of the tube containing the copper. The tube may then be broken and the inner side of the fragments examined with a microscope, for octahedral crystals of arsenious oxide. The copper and the acid used must be shown to give no stain on prolonged boiling with distilled water. This blank ex- periment must always be performed. Marsh's test may be conducted as follows : — Although the indications afforded by it are not conclusive in the presence of organic matters, it should always be used to confirm Reinsch's test. Into a flask holding about 150 c. c. (fgv), introduce some pieces of zinc, free from arsenic and antimony ; then pour over these some water acidulated with sulphuric acid ; close the flask with a cork containing a funnel tube, and a delivery tube drawn to a fine point and containing a pledget of cotton in the end at the cork, arranged as in Fig. 51. After allowing the generation of hydrogen to go on for a considerable time, to expel the air from the upper part of the flask, say half an hour, light the gas at the open end of the delivery tube, and press a cold porcelain surface down upon the flame. If the materials used are free from arsenic and antimony, there will be no black stain pro- dviced on the porcelain. Having determined that the apparatus and materials are free from arsenic, put out the flame and pour the .suspected fluid through the funnel tube, so as to admit little or no air with it into the flask. Now ignite the gas and test the flame again with the cold porcelain surface. A brilliant black or brown stain, soluble in a solution of sodium hypochlorite, is probably arsenic. Moisten one of these spots with nitric acid, when it should dis- appear ; evaporate the acid over a lampj moisten the spot with ARSENIC. 189 water, and hold the dish over a vessel containing sulphuretted hydrogen, prepared by the action of sulphuric or hydrochloric acid upon sodium or potassium sulphide. If the stain was due to arsenic the .spot will turn lemon -yellow. The antimony mirror is insoluble in sodium hypochlorite (Labarraque's solu- tion) and after treatment as above gives an orange stain. Now soften the glass, bend the delivery tube downward and let it dip into a solution of AgNOj ; after an hour, pour some very weak solution of NHjOH upon the surface of the AgNOj solution. Yellow precipitate at line of separation = arsenic. If the sub- stance to be tested is a solid, a small portion of it may be thrown upon a glowing charcoal, when arsenic, if present, will give an odor resembling garlic. These tests will be sufficient to enable Fig. 51. the physician to decide upon the presence of arsenic during the life of the patient, and guide him in his treatment and behavior. Fleitmann's Test. — Heat to boiling in a test tube, a strong solution of potassium hydroxide, in which some pieces of zinc or aluminium have been placed. Add a drop or two of the suspected solution, spread a cap of filtering paper over the mouth of the tube, and moisten it with a little nitrate of silver solution. A brown or black stain of metallic silver will appear upon the paper, if arsenic is present. The arsenous oxide is de- composed, and the nascent hydrogen combines with the arsenic and forms arsine AsHs, which reacts with the silver nitrate, reducing it to metallic silver. This test is very valuable, enabling the analyst to distinguish between arsenic and antimony, which latter does not give the above reaction. igO MEDICAL CHEMISTRY. Sulphuretted hydrogen HjS passed into an acidulated solution containing arsenious acid, throws down a lemon-yellow precipi- tate, consisting of AsjSj, which dissolves in ammonia, and is reprecipitated by acids. Solid arsenious oxide is mixed with some powdered charcoal and dry potassium carbonate, and placed in the bottom of a very narrow test tube (or, better, a glass tube, drawn out, and having a bulb at one end. Fig. 52), and heated. The arsenious oxide is reduced and metallic arsenic is deposited in the form of a ring, on the cooler part of the tube. The lower part of the tube may now be broken off and the metallic arsenic heated, there being free access of air ; the arsenic is oxidized and deposited in the upper part of the tube, in the form of octahedral crystals of arsenious oxide. Ammonio-nitrate of silver givesa lemon- yellow precipitate with arsenious acid solutions of arsenite of silver, AgaAsOj. It gives a brown precipitate, AgsAsOj, with arsenic acid. Fig. 52. Ammonio-sulphate of copper gives a grass-green precipi- tate of arsenite of copper, also called Scheele's green, CuH- AsOs, with solutions of arsenious acid. Bethendorfs Test. — Add a freshly prepared solution of stannous chloride to any arsenic compound, dissolved in strong hydrochloric acid, place in the mixture a small piece of tin foil, and apply heat ; a brown color or grayish-brown precipitate is formed, according to the amount of arsenic present. Gutzeit's Test. — Place in a test tube about i gram of pure zinc, and add about 5 c. c. of dilute (about 6 per cent.) sulphuric acid, then add about i c. c. of the solution to be tested (which should not be alkaline). Now fix a plug of cotton, moistened with lead acetate solution, in the test tube not far from the top, and fasten over the mouth of the tube a cap made of three thicknesses of filter paper, and apply a drop or two of strong solution of silver nitrate to the upper one, and place the tube in a dark box, and allow it to remain for some time. If arsenic is present in the solution, a bright yellow stain will appear upon the filter paper, which upon the addition of water becomes black or brown. Antimony when subjected to the above test, gives a dark color at once, without showing a ARSENIC. 191 yellow color previously. The zinc and the sulphuric acid should be tested before applying the above test to make sure that they contain no arsenic. The chemist who undertakes the analysis, in cases of supposed poisoning, has no easy task. He must not confine his tests to any one poison. Poisons are generally divided into two groups, inorganic and organic. The limits of this work will not allow us to describe the details of procedure for the chemist, who will consult special works on toxicology. In searching for mineral poisons, the organic matters must first be destroyed or separated by dialysis. For the latter process, see Part I, Art. 82. For the destruction of organic matter, two methods may be used. The solid matter — the stomach, and other organs — are to be cut in fine pieces and placed in a new porcelain dish, mixed with hydrochloric acid, and heated over a water bath. Small quantities of pure potassium chlorate are put in, from time to time, and stirred, until the organic matter is destroyed. Or, sulphuric and nitric acids are used to thoroughly char the organic matter, and the whole diluted with water and filtered. The metals, except lead and barium, pass into the filtrate, and can be detected by either of the methods given above, or by other methods. These solutions may be treated with hydrosulphuric acid gas from 24 to 48 hours, when copper, lead, bismuth and mercurj give black or brown precipitates; arsenic, cadmium, and sometimes tin, give a yellow, and antimony an orange precipi- tate. In searching for arsenic, the yellow precipitate obtained, is separated from the liquid by filtration. A portion of this is to be preserved in a sealed glass tube. The remainder is oxidized with nitric acid, fused with sodium carbonate and nitrate, and the sodium arsenate thus formed may be made to yield silver and copper arsenates ; the former a reddish-brown, and the latter a green precipitate. Other portions are converted into the octahedral crystals of trioxide, the metallic state, etc., the object being to present the poison in court in as many different states as possible, so as to avoid the possibility of doubt in the minds of the jury. If the yellow sulphide, soluble in ammonia, the black metal (so called), the octahedral crystals, the mirrors with the above-mentioned properties, the coated copper obtained by Reinsch's test, the black deposit from silver nitrate, from Marsh's test, with arsenite in the filtrate, the arsenite and arsenate of silver, and arsenite of copper, etc.. 192 MEDICAL CHEMISTRY. etc., are obtained, with proper precautions^ there is no room for doubt that the substance is really arsenic. For further directions on this subject, the student is referred to Taylor on Poisons, or Woodman and Tidy on Forensic Medi- cine and Toxicology, or some other similar work. ANTIMONY. (Stibium.) Sb ^ 119 6. Sp. gr. 6.71. Melting point 450° C. (842° F.). 239. Occurrence and Preparation. — Antimony occurs native; but the principal source is the tnsulphide Sb2S3, called stibnite. It occurs in a number of other ores as sulphide, or oxide. The element is easily obtained by roasting the sulphide, and then fusing the oxide thus obtained, with charcoal. Properties. — Antimony is a bluish-white, brittle, crystalline' solid, isomorphous with arsenic, and resembling zinc in color and lustre. Tarnishes with difficulty, but takes fire at a red heat. It unites readily with chlorine, forming two chlorides, SbCla and SbClj, both of which are decomposed by excess of water. In physical properties it resembles the metals, with which it forms alloys. In chemical properties, it plays both the positive and negative roles with facility. It is used as a con- stituent 0/ type metal, Babbitt's anti-friction metal, Britannia, etc., to give hardness, and to cause them to expand in cooling and completely fill the moulds. 240. Hydrogen Antimonide, Stibine, Antimoniuretted hydrogen (SbHj). — A colorless, odorless gas, formed in the same conditions as the corresponding compound of arsenic ; /. e., by nascent hydrogen on reducible antimony compounds. It differs from that compound in being much less poisonous, and giving a different reaction with solutions of silver nitrate, as shown in the following reactions: — 6AgN03 -^ AsH, + 3H,0 = 6 HNO3 + HjAsO, -|- sAg^ 3AgN03 -I- SbH, = 3HNO3 + SbAg3 Metallic Silver Silver. Antimonide. By carefully floating a solution of ammonium hydroxide over the silver nitrate solution, after passing the gas through it for some time, a yellow precipitate of arsenite of silver will be formed at ANTIMONY. 193 the line of separation of the two liquids, while, in the case of antimony, no such precipitate will be formed. This gas is formed in Marsh's apparatus when antimony is present, and it is likely to be confounded with arsenic unless very great pains be taken to avoid it. The mirrors obtained on the porcelain, or in the delivery tube, require a higher temperature to volatilize them in the case of antimony ; they are difficultly soluble in hypochlorite solution, are sooty and less brilliant in appearance, there is no garlic odor, and by oxidation thev do not form crystals. 241. Chlorides, Bromides and Iodides. — Two chlorides and two oxychlorides exist. Antimony Chloride — A. Trichloride, or A. Protochlo- ride — Butter of Antimony (SbClg) may be obtained by dis- solving the trisulphide in hydrochloric acid. SbjSj + 6Ha = aSbCI, + 3HjS. At low temperatures it is a crystalline solid, and melts at 73- 2° C. (164° F.) to a yellow, oily-liquid. A solution of sp. gr. 1.47 is sometimes used as an escharotic. On the addition of consider- able water, this chloride is decomposed into the oxychloride, (SbOCl), formerly called powder of algaroth. SbClj is poisonous, acting both locally and as a true poison. Antimony Pentachloride (SbClj) is a fuming, colorless liquid, of little interest to the medical student. The iodides, bromides and fluorides, are similar to the trichloride in composi- tion and properties. The iodide has been used in medicine. 242. Sulphides of Antimony. — Two sulphides and several oxysulphides are known. Antimony Trisulphide — Sul- phuret of Antimony — Black Antimony — Antimonii Sulphidum (U. S. P.), Sb^Ss, occurs native as a steel-gray, crystalline solid. Artificially, it may be prepared as an orange- colored powder by precipitating a soluble antimony salt with hydrogen sulphide. When the native ore is roasted in air it is partially decomposed, and fuses into a vitreous, somewhat trans- parent mass, known as glass of antimony, or crocus. Antimonii Sulphidum Purificatum (U. S. P.) is made by reducing sulphide of antimony to a very fine powder, and then macerating with ammonia water for five days, and finally washing with water and drying. It is a grayish-black powder, having no lustre, and being without odor or taste. Antimonii Sulphuratum (U. S. P.) is a reddish-brown powder prepared by dissolving the native sulphide in a solution 17 194 MEDICAL CHEMISTRY. of sodium hydroxide, and re-preeipitating the hot solution with sulphuric acid. It contains a little antimonious oxide (SbjOs), and is used mostly in pill form. Dose, gr. ij to xx. Phimmer's Pill, Pil. antimonii comp., contains this sulphide, with calomel. By treating a hot solution of the trisulphide with sodium hypo- sulphite, a fine red precipitate of oxysulphide is obtained, which is used as a pigment, under the name of antimony vermilion. Kermes' mineral is another name for sulphurated antimony. Antimonic Sulphide, or Antimony Pentasulphide, (SbaSs) is best obtained by decomposing sulphantimoniates with a dilute acid. It is an orange-red or brown powder, readily soluble in alkalies and alkaline sulphides, forming antimoniates with the general formula Ms'SbOj, in which M stands for a me- tallic atom. Sulphantimoniates of silver, lead, and iron, occur as minerals. 243. Oxides and Acids of Antimony. — Three oxides are known. Antimony trioxide, .... SbjOj, Metantimonious acid HSbO,. " pentoxide, . . . SbjOj. " tetroxide, . . . Sb^O^ or SbO SbOj. Antimony Trioxide, Antimonii Oxidum U.S. P. — (Sb.iOa) is obtained by roasting the metal in air, or by treating it with HNO3 and evaporating excess of acid. It is a white, amorphous powder capable of being sublimed. It is insoluble in water, alcohol or nitric acid. Metantimonious Acid (HSbO^) is obtained as a white precipitate by adding a solution of sodium carbonate to a solu- tion of SbClj. 2SbCls 4- sNa^CO, + H^O = aSbOjH + 6NaCl + aCOj. By boiling, this acid is changed into the trioxide. It reacts with both acids and alkalies to form salts. Thus, we have NaSbO,, SbOCNOs) and SbCNO,),. We also have antimony sulphate Sb2(S04)3— and antimonyl sulphate (SbO^CSOi) — the former obtained by dissolving the oxide in strong, and the latter in dilute sulphuric acid. Both are decomposed by excess of water. Antimonic Acid (HaSbOj) — is obtained, as a white powder, insoluble in water and nitric acid, by treating antimony with warm concentrated HNO3. ANTIMONY. 195 Pyro-antimonic Acid (H^SbjO,) — is also known, and may be obtained by treating its salts with hydrochloric acid. By gently heating either of the above acids, antimony pentox- ide is obtained as a yellow, amorphous mass, and by a stronger heat, with free access of air, it is converted into tetroxide — SbjOi — which is usually regarded as an antimoniate of antimonyl (SbO SbOa). It is a white, non-volatile powder, becoming yel- low when heated. 244. Potassium Antimonyl Tartrate. — Tartar Emetic — Antimonii et Potassii Tartras (K(SbO)C4H406.HjO) is one of the most commonly employed compounds of antimony. Prepared by boiling 3 parts of SbjOs with 4 parts of cream of tartar (KHC^H^Oe) in water, for an hour, filtering, evaporating the filtrate, and allowing it to crystallize out. It occurs in small, transparent, rhombic crystals, which effloresce in air, and have a sweetish, afterward disagreeable, metallic taste and acid reaction. Soluble in 17 parts of water at i5°C, (59° F.), and 3 parts boil- ing water ; insoluble in alcohol. Its solutions are incompatible with alcohol, hydrochloric acid, and alkaline carbonates. Free tartaric acid prevents the precipitates caused by the above reagents. On being heated to redness it chars. It is used in medicine, and enters into the composition of Syr. scillae compositus, and Vinum antimonii. The dose of tartar emetic is gr. j-ij (.065-. 125 grm.), as an emetic ; as an expectorant, gr. Jj- to gr. ^ (.004-.016 grm.) ; of the wine, 10 to 30 drops. 245. Physiological Action. — Locally, the soluble com- pounds of antimony act as powerful irritants. Tartar emetic causes a pustular eruption resembling variola, which is accompa- nied with fever and systemic disturbances. Cases of poisoning from antimony, used as a mordant in dyeing clothing, have been reported. Internally, tartar emetic is employed as an expectorant, sudorific, sedative, nauseant and emetic, according to the dose used. In full doses it causes vomiting, purging, and griping pains, with great depression. In excessive quantity it acts as an irri- tant poison, and has produced death by syncope, preceded by convulsions and delirium. One and a half grains (.092 grm.) have produced death, but recovery has occurred after very large doses, because of the rejection of the poison by vomiting. The treatment should consist in promoting free vomiting, or removal of the poison with the stomach pump. The proper antidote is tannin, which forms an insoluble compound with antimony ; it may be administered in the form of infusion of tea. 196 MEDICAL CHEMISTRY. oak bark, nutgalls, etc. Stimulants are then to be admin- istered. In suspected cases, examine the urine or viscera by Marsh's test (Art. 238J. Soluble salts of antimony give an orange-colored precipitate with HjS, in acid solutions, which is soluble in yel- low ammonium sulphide, and in strong hydrochloric acid (HCl). In Reinsch's test, a bluish stain is obtained, but the sublimate obtained from it is amorphous, not crystalline. (See Art. 238.) BISMUTH. 13i = 208.9. 246. Occurrence and Preparation. — Occurs native, and as a sulphide — bismuthinite. 'The element is obtained by roast- ing the sulphide in air, and reducing the resulting oxide with charcoal. Properties. — Bismuth is a white, metallic-looking solid, with a bronze tint. Sp. gr. 9.9. Brittle, and crystallizes in rhombohedrons ; fuses at 267° C. (512.5° F.), volatilizes at a white heat, and if heated in air it burns to Bi^Oj. HNO3 and hot H2SO4 dissolve it, but HCl does not. Water precipitates basic salts from the solutions of the neutral salts. It alloys with the melals, and is sometimes described as a metal. 247. Bismuth Chloride (BiCls) may be obtained by treat- ing the element with chloiine or aqua regia. It is a soft, white, deliquescent, volatile solid. Water, added to its solutions, pre- cipitates the white oxychloride. BiClj + HjO = BiOCl + HCl. This reaction resembles that of SbClj. BiOCl, as well as the subnitrate, is sold as pearl powder, or pearl white, and used as a cosmetic. They blacken by HjS. The compounds BiBrj, and Bils are similar to BiClj. Bismuth does not form a hydride (BiHs), as do the rest of the group. 248. Oxygen Compounds. — Bismuth oxide (BijOs) is a yel- low powder, insoluble in water and alkalies ; it may be prepared by roasting bismuth, or heating the nitrate or carbonate. When chlorine is passed through a solution of potassium hydroxide, in which BijOs is suspended, bismuthic acid (BiOsH) is precipitated as a red powderr. On gently heating this, the pentoxide, or bismuthic oxide (BijOj), is formed. Bismuth hydroxide (BiOsHj) is not known, but a metahydroxide (BiOjH) is precipitated when caustic soda or potassa is added to a bismuth BISMUTH. 197 solution, or to the nitrate suspended in water. This oxide is the one first precipitated in testirg for sugar in Boettger's test. The oxides BijOj and Bi,©! are also known. 249. Bismuth Nitrate (BiCNOsjg) is formed by dissolving bismuth, or the basic nitrate, in nitric acid and evaporating, when it crystallizes in large transparent tables, (Bi(N03)3.5H20). It is soluble in a little water, but is decomposed by a large amount, into a basic nitrate or subnitrate. The reaction varies with the amount of water used. _ NO3 T» — NO3 m-N03 + 2H,0 = Ul-OH + 2HNO3, or Ul— NO3 ill— OH P, NO3 T, NO3 JJI-NO3 + H,0 = JJl-NO, + HNO3, or g[-N03+H.O=gpO^ + .HN03. Bismuthi Subnitras (U. S. P., Br. P.). — As will be seen, the subnitrate of bismuth is not a definite and fixed compound, but a mixture. It is a white powder, insoluble in water, but soluble in nitric acid. As arsenic and bismuth frequently occur together, the latter is apt to be contaminated by the former. Should unpleasant effects arise from its use, it should be tested with one of the tests described under arsenic (^. v.). It is used internally, and as a dressing for wounds. A solution of 2 pts. BiON03, and 4 pts. KNaCiHiOe, in 100 c. c. of a strong solution of sodium hydroxide is used as a delicate test for diabetic sugar. It becomes black on boiling, in the presence of glucose, from reduction of the bismuth. 250. Bismuth Subcarbonate — Bismuthi Subcarbonas B,./C03 (U. S. p.).— Bismuthi Carbonas (Br. P.)— / O is a light, Bi— OH \0H white, odorless and tasteless powder, insoluble in water, and formed by the action of alkaline carbonates upon solutions of bismuth. Heat changes it into Bi203,H20, and carbon dioxide. Bismuth Sulphate (Bi2(S04)3) is formed by dissolving bis- muth in sulphuric acid. It is of no special interest to physi- cians. 198 MEDICAL CHEMISTRY. 251. Bismuth Citrate (BiCeHsO,) is a white, amorphous, odorless and tasteless powder, insoluble in water or alcohol, but soluble in ammonium hydroxide. Prepared by boiling the sub- nitrate in a solution of citric acid, and precipitating the citrate with water. By dissolving the citrate in dilute ammonia water, and cautiously evaporating to a syrup, and spreading on glass, shining, pearly or translucent scales of Bismuth et Ammonii Citras are obtained, soluble in water. 252. Physiological Action. — The bismuth salts in medici- nal doses are tonic, antispasmodic, mildly astringent and anti- fermentative. They are used to allay gastro-intestinal irritation and diarrhoea. When administered in considerable quantities they form black stools, from the presence of the sulphide formed by the H^S of the intestines. In many cases of excessive diar- rhoea, with acid fermentation in the stomach and intestines, this blackening does not occur, and its appearance marks an im- provement in the case. Cases of poisoning by large doses of the salts of bismuth are generally, if not always, due to the presence of arsenic in them. 253. Tests. — Water precipitates bismuth from its solutions, in the absence of much free mineral acid. Hydrogen sul- phide and ammonium sulphide give a black precipitate, insoluble in water, dilute acids and alkaline sulphides. Potas- sium, Sodium and Ammonium Hydroxides give a white precipitate, insoluble in excess of the reagents. Infusion of nutgalls gives an orange precipitate. Potassium Iodide gives a brown precipitate, soluble in excess of reagent. A piece of paper dipped in a solution of potassium sulphocyanate and dried, forms a yellow spot when a drop of a solution containing bismuth is dropped on it. CARBON. 199 GROUP IV. Carbon, C = 12. Silicon, Si = 28. Germanium Ge = 72. Tin (Stannum), Sn = 118. Lead (Plumbum), Pb — 207. CARBON. 254. Occurrence. — Carbon occurs native in the diamond, graphite (black lead), and the various forms of coal. In com- bination it occurs in all the organic bodies, petroleum, fats, oils, and in native carbonates as marble, dolomite, etc. 255. Varieties. — Carbon exists in three allotropic states, the diamond, the graphite, and amorphous carbon. The diamond occurs in alluvial deposits in Brazil, India, Borneo, South Africa, and in small quantities in other localities. The so-called Cali- fornia diamonds and Brazilian pebbles are crystals of quartz, (SiOa). The diamond is pure crystallized carbon, possessing a brilliant lustre and a high power of refraction, and is the hardest substance known. It crystallizes in rhombohedra of the first system, but cleaves readily into octahedra. It occurs colorless, as well as colored through all shades of yellow, brown and black. The sp. gr. is 3.5. Heated in the oxy hydrogen blowpipe flame, or in oxygen gas, it burns to carbon dioxide, and is slightly softened by the heat of the electric arc. Graphite, or Plumbago, occurs as a native mineral, having a grayish-black color, a lustre almost metallic, and a soapy feel. It leaves a black streak upon a white surface, on account of which, it is used to miake lead pencils, and is called black lead. It sometimes occurs in short, six-sided prisms. It burns in an atmosphere of oxygen, with more difficulty than the diamond, furnishing carbon dioxide, and leaving from 2 to 5 percent, of ash. Some of the purer varieties can be made directly into pen- cils, but this is not common. The poorer varieties are ground to a powder, heated with potassium chlorate (KCIO3) and sulphuric acid (H2SO4), or with strong nitric acid, washed with water, heated to red heat, and then mixed with some adhesive material and pressed into cakes. These cakes are then sawed into suit- able strips and mounted. 20O MEDICAL CHEMISTRY. Graphite conducts heat and electricity well. It is also used ill the manufacture of crucibles, as a lubricant for very heavy machinery, and as a stove polish. It may be obtained artifically by fusing amorphous carbon with cast-iron ; on cooling the mixture and dissolving the iron with dilute acid (HCl), graphite is left in the form of minute hexagonal plates. Amorphous carbon is found native in the form of many varieties of coal. Artificially, it is prepared by the partial burning, or carbonizing, of organic matter, such as wood, pitch, blood, etc. Soot, or Lampblack, one of the purest forms of amorphous carbon, is prepared by the imperfect combustion of turpentine, pitch, or heavy oils, rich in carbon. It is used principally as a pigment. Animal charcoal or bone black is obtained by the carbonization of animal matter from slaughter houses^ (blood, bones, etc.), and possesses, in a remarkable degree, the power of removing the coloring matter from organic solutions filtered through it. It is used in refining sugar, to remove the color from the solution of raw sugar. Charcoal, Cdrbo ligni U. S. P., is carbonized wood, retaining, usually, the form and grain of the wood and the ash contained in the same. In preparing it, the wood cut into suitable lengths, is piled up on end into a conical heap, a trough made of boards being laid from the circumference on one side, to the center, to supply air in burning. The whole heap is then covered, first with straw or leaves, and finally with dirt, about six or eight inches in thickness, except a hole at the center on the top. The fire is lighted and is allowed to burn slowly, until the flame almost ceases to come from the hole at the top, or until the gaseous products have all burned off. This opening at the top, as well as the draught hole, is now covered over and the fire allowed to smoulder for a time, when the heap is torn down, and the remaining fire extinguished with water. Charcoal is used as a fuel, in the manufacture of gunpowder, and sometimes in the construction of filters, as it possesses, in a feebler degree than animal charcoal, the power of destroying noxious odors, and filtering coloring matters from organic solu- tions. One volume of it absorbs 90 volumes of NH3, 55 volumes of HjS and 9 volumes of oxygen, at 100° C. (212° F.) It is very porous, and burns with little flame. Coke is the porous mass left in the retorts from the destructive distillation of mineral coal in the production of illuminating gas. Gas retort carbon is a compact, hard mass found adhering to the inside of the retorts in the above process of manufacturing coal gas. . It CARBON. 20 t has a metallic lustre, at times, and is a good conductor of electri- city. For this reason and because of its durability it is used for the negative plate in the construction of many forms of the gal- vanic cell, and for the poles in the arc electric light. Mineral coals, as anthracite, bituminous, brown, and cannel coals, lignite, peat or turf, etc. , are the results of a slow decay, under certain conditions, of vegetable matter. The proper conditions for formation of coal seem to be, enough water to cover the fallen timber or vegetation, and then a covering of clay or mud, to exclude the air, and the application of pressure to the mass. The liquid and volatile portions are gradually lost, leaving the carbon behind. The final product of this change, assisted by subterranean heat, is anthracite coal, which often contains 96 to 98 per cent, of carbon, and almost no volatile products. 'Petroleum oil is believed to be the expelled liquid portions of the wood, separated from the anthracite coal by heat and pressure. Bituminous coal is a softer, less compact, less decayed variety. It often contains the structure of the wood. It burns with a smoky flame, while the anthracite furnishes very little or no flame. Brown coal, lignite, and wood coal are names of less perfect varieties than those before mentioned. Peat, or turf, is a mixture of mud with partially decayed plants and roots, obtained from certain marshy districts. It is used as fuel. Cannel coal is a compact, even-textured coal, without lustre. It takes fire readily, burning with a clear, yellow flame. It has been used for candles — hence the name. 256. Properties. — Carbon is insoluble in all ordinary menstrua, but soluble to a slight extent in molten cast-iron, forming a carbide. It is fused and volatilized only in the electric arc. At ordinary temperatures it is permanent in air. At high temperatures it has a strong affinity for oxygen, and on this account it is used as a reducing agent in smelting the ores, from which it removes the oxygen. Indirectly, it enters into combination with a great many of the elements. Organic bodies are formed of carbon in combination with hydrogen, nitrogen, and oxygen. Most combustible bodies contain carbon. 257. Official Preparations. — Animal Charcoal, Carbo Animalis, U. S. P., is charcoal prepared from bones by partially burning them, and distilling off the volatile products and char- ring the remaining organic matter. It occurs in granular fragments, or in powder of a dull black color, which, when ignited, leaves about 85 per cent, of ash. This ash should be almost entirely soluble in hot HCl. 18 202 MEDICAL CHEMISTRY. When animal charcoal is boiled for a few minutes with a solution of potassium hydroxide the filtered solution should be colorless, or nearly so. Carbo Animalis Purificatus, U. S. P. This is prepared by heating the above with dilute HCl to dissolve out the calcium phosphate. The quantity of ash after ignition should not be more than 4 per cent. Carbo Ligni, U. S. P., is prepared from soft wood, and very finely powdered. It should be kept in well-closed vessels. Fig. 53. The Manufacture of Coal Gas. 258. Coal Gas. — Illuminating gas, as it is often called, is made on a large scale by the dry or destructive distillation of bituminous coal. In principle, the manufacture is simple; but in practice, it requires considerable skill to prepare a good illu- minating gas. During the distillation, which is conducted in horizontal, semi-cylindrical, fire-clay or cast-iron retorts set in brickwork, a variety of products are produced besides the gas, such as tar, heavy oils, lighter oils, steam, ammonia from the nitrogen of the coal, etc. There is left in the retort a porous, friable mass, called coke. After the retorts have been used for CARBON. 203 some weeks, there is to be found lining their inner surfaces a very compact layer of carbon, usually known as gas retort carbon. The coal is distilled at a bright red heat, and the volatilized products are conducted into a large, horizontal iron pipe, half filled with water, into which the pipes from the retorts dip. (See Fig- S3-) This is called the hydraulic main. A large part of the coal tar and heavy oils condense in this main. The volatile products are then made to traverse a series of upright tubes, in the form of an inverted U, called condensers. The lower end of one limb of each condenser dips under water, so as to cool the gas and to wash out the ammonia. After traversing a num- ber of these condensers, where the remainder of the tar, steam and ammonia are condensed, the gas passes to the purifiers. These are composed of a series of large boxes, in which are sev- eral perforated shelves, or trays, holding fresh slaked lime, or a mixture of sawdust and iron oxide. The gas is passed slowly through these purifiers, so as to expose it to the action of the lime or iron oxide, to remove HjS, CO2, and other volatile acids, if present. In some plants there is an additional process of washing the gas by passing it through weak sulphuric acid to remove the small quantity of ammonia still remaining. The tar and ammonia liquor are sold as by-products, and the latter fur- nishes a very considerable portion of the ammonium compounds of the market. After passing through the purifiers, the gas is conducted in underground pipes to the gasometer, to be stored until needed. The gasometer is a very large, tub-shaped vessel, made of boiler-iron, floated bottom upward upon water, and balanced by weights attached to chains passing over pulleys at the top of iron pillars, which are erected around the gasometer for that purpose. As the gas is forced into the gasometer, the latter rises out of the water, and sinks again as the gas is used. - Various other processes for the manufacture of gas have been used with varying success ; such as the distillation of the heavy petroleum oils, either alone, with coal, or with admixture of the vapors with air or steam. Gasoline, or air gas, is air saturated with the vapors of the very volatile oils from petroleum. Water Gas is very largely used in all large cities, owing to the cheapness of manufacture. It is made by the action of steam upon coal heated to a red or white heat. The gas thus produced is, in some works, mixed with vapor from naphtha, and then 204 MEDICAL CHKMISTRY. again strongly heated in retorts, and finally purified as in ordi- nary coal gas. Composition. — The composition of coal gas varies somewhat with the composition of the coal used, and the temperature of the retorts during the distillation. The following figures represent the composition of coal gas and water gas supplied to Brooklyn in 1883: — Coal Gas. Water Gas. Carbon dioxide, 0.0 0-3 Carbon monoxide, 7-9 28.25 Hydrogen, 50.2 30-3 lUuminants (CjHj, CjH^, etc.), 4-3 12.85 Marsh gas (CHJ, 29.8 21.45 Nitrogen, 7.8 6.85 259. Carbon and Oxygen. — There are four oxides of carbon known, having the formulae CgOa, C4O3, CO, and COj. The first of these compounds is a light brown powder, formed by heating the suboxide (QO3). Carbon Suboxide is an amorphous extractive matter formed by the action of an electric current upon carbon monoxide. Carbon Monoxide (CO) is a colorless, tasteless, almost odorless, combustible, very poisonous gas. It is always produced when carbon or bodies containing it are burned with an insufficient supply of oxygen or air, or by conduct- ing carbon dioxide over or through red hot coals. COj-f-C^aCO. It may be prepared by warming oxalic acid with sulphuric acid. HjCPt + H.,S04 = H4SO5 (or HjO. HjSO^) + COj + CO. The mixed CO2 and CO are passed through a solution of so- dium hydroxide to absorb the COj, and the CO remains. One part of potassium ferrocyanide, warmed with nine parts of HjSO«, may be used to give the gas in nearly a pure state. Its density is 14. It is almost insoluble in water, but soluble in a solution of cuprous chloride in ammonium hydroxide. It burns in the air with a bluish-lavender flame, producing the higher oxide — CO2. Owing to this property, it plays an important part in the reduction of ores in the blast furnace. It does not support combustion or respiration. It diffuses readily through red-hot cast-iron, and frequently escapes from stoves and hot air furnaces. 260. Physiological Effects. — It has the power of combining with the haemoglobin of the blood, and of expelling the oxygen. It thus acts as a narcotic poison, causing dizziness, headache, CAHBON. 305 nausea, incoordination of movements, convulsions, and death. If the carbon monoxide be in sufficient quantity to saturate all the haemoglobin, recovery is seldom, if ever, realized. The blood has a light red color, and does not coagulate after death, or decompose as readily as normal blood. When diluted and examined with the spectroscope, it gives two absorption bands, similar to those in No. lo Frontispiece, but they are removed somewhat toward the violet end of the spectrum. If the hsemo- globin is only partially saturated, recovery may take place, but very slowly — debility, anorexia, etc., remaining for days. Air con- taining 0.5 per cent, kills birds in three minutes ; 2 per cent, renders a guinea pig insensible in two minutes. Artificial res- piration is of little use. Transfusion of blood or intra-venous injection of sterilized saltsolution, 0.7 per cent., is the most prom- ising treatment. The sources of danger are open fires, defective draught in chimneys, escape of coal gas, and especially " water gas," from defective fittings, or from leaks under the ground. When the ground is frozen and the gas escapes into the soil near a cellar, the gas diffuses through the ground into the cellar, and, as it is thus deprived of its odor, persons may be poisoned and not know where it comes from. Coal-gas poisoning is essen- tially a poisoning by the carbon monoxide which it contains. Suffocation by coal gas is not very different from suffocation by oth,er gases, and should be distinguished from poisoning. 261. Carbon Dioxide — Carbonic Anhydride (CO2), sometimes called carbonic acid gas, is found free in the air in the proportion of about 4 parts per 10,000; and in ordinary well ventilated rooms from 5 to 6 parts per 10,000. It is found in volcanic gases and in solution in many mineral springs. It sometimes accumulates in dangerous quantities in mines, wells, and cellars, and is then known as " choke damp." It may be detected in such places by lowering a candle. (See below.) It is produced when carbon or its compounds are burned with a free supply of air, by alcoholic and other fermentations, by the respiration of animals, and by slow oxidation of organic matter in the natural process of decay. In the laboratory, it is obtained by the action of an acid upon a carbonate. CaCOj -f 2HCI = COj + CaCla + H,0. Carbon dioxide, at ordinary temperatures and pressures, is a colorless, transparent, odorless, tasteless (by some sweetish) gas. Sp. gr. = 1.524. Density = 22. Under a pressure of 36 at- mospheres at 0° C. (32° F.), it is condensed to a colorless, 2o6 MEDICAL CHEMISTRY. mobile liquid, of sp. gr. 0.94. Above 32.5" C, it cannot be liquefied at any pressure. This is known as the critical point in temperature. When the liquid is exposed to the air it rapidly evaporates, producing a temperature so low as to freeze a portion of it to a snow-like solid, the temperature being sometimes as low as — i3o°C. (—202° F.). The gas extinguishes the combustion of burning bodies, and animals die very quickly in it. Death has resulted from persons entering mines, wells, and fermenting vats where the gas has accumulated. It is un- safe for a man to venture into a well or other place where a candle will not burn. CO^ is soluble in its own volume of water, at the ordinary temperature and pressure, forming a solution of car- bonic acid, H2CO3. Common soda water is a solution of the gas in water under pressure ; it contains no sodium salt, as its name would imply. 262. Physiological Effects. — These vary with the degree of concentration of the gas and its dilution with other gases. If the gas be pure, it causes death instantly, by apnoea from spasm of the glottis. When somewhat diluted, there is, at first, great loss of muscular power ; the person becomes livid, sinks down, and dies without a struggle. When still more diliite, there is, at first, irritation of the throat, then giddiness, ringing in the ears, loss of muscular power, with rapid pulse and respiration, and occasionally vomiting and convulsions, finally ending in coma and death. The amount of the gas that can be tolerated in the air depends not only upon the quantity of it actually present, but also upon the source of it. Thus, when the source of the gas is animal respiration or combustion, the oxygen is withdrawn from the air at the same time, and a much smaller quantity will prove fatal than where the gas is simply added to the normal atmosphere. If the CO2 is simply added to the air, 10 per cent, may be regarded as poisonous, and even 8 per cent, will prove injurious. If, on the other hand, the oxygen be increased, an air containing even 20 per cent, may be breathed by animals for a short time without fatal results. A taper will burn in an air containing 8 per cent, of COu provided the oxygen be present in normal quantity, and will burn feebly in such an air containing 10 per cent. Where the COj is produced by respiration, the injurious effects are soon perceived, and are due to several causes ; viz.: the deficiency of oxygen, the presetice of too great a quantity of COj and moisture, the rise in temperature, and the action of the organic matter exhaled from the lungs and skin. CARBON. 207 The expired air contains from 4 to 5 per cent., or about .78 cubic feet, of COjperiiour, and there is absorbed .94 cubic feet of oxygen. A stearin candle gives off .5 cu. ft. of CO2, and uses up I cu. ft. of oxygen. A gas light burning 5 feet of gas per hour (12 candle power) gives off very nearly 6 cu. ft. of CO2, or 3. 7 times as much as one man ; as much heat as two men ; removes more oxygen than 5 men; and gives off nearly as much water vapor as 5 men. More than 6 parts of CO.; per 10,000 of air renders it oppressive, and should not be allowed. Assuming the amount of CO, given off in an hour by an adult to be. 7 cu. ft., and normal air to contain 4 parts, it would require about 3500 cu. ft. of air per hour for each adult occupant of a room, in order that it should not receive more than two parts per 10,000 of CO2, or two cubic feet per 10,000. Dr. Parkes fixes the amount necessary at 2000 cu. ft. per hour. It is impossible to change the air of a room oftener than 3 or 4 times per hour without causing uncomfortable draughts ; and it would, therefore, require 700 to 1000 cu. ft. of room space in order to keep the air of the room in a proper condition. If lights are used, which also pollute the air, a corresponding calculation must be made for them. A common oil lamp, or two sperm candles (not an argand lamp), will contaminate the air about the same as an adult man. The English Poor-Law Board's requirements for dormi- tories, to prevent over-crowding, are — Cu. ft. 1200 Lying-in cases andofTensive sick. 850 Sick. 700 Infirm. Same room night and day. 500 InBrm. Separate room in day. 300 Healthy. These figures are, of course, too small for general use. Parkes quotes Morin as giving the following amount of fresh air neces- sary to be furnished to each adult per hour in the following cir- cumstances: — Day. Night, In Barracks, . . . 1059 cu. ft. per hour. 21 18 cu. ft. per hour. " Workshops, . .2118 " " " Schools, . . . 1059 " " " Hospitals, . . 2825 " In sleeping apartments, the amount of space allowed to each individual should not be less than 1000 cubic feet, i. e., a room 10 X TO X 10 ft- j t>ut, as the proportion of carbon dioxide would accumulate slowly, and as a much larger amount of the 2o8 MEDICAL CHEMISTRY. gas may be borne without serious discomfort, even one-half this capacity may be tolerated with littleinconvenience beyond a feel- ing of fatigue or sleepiness in the morning. Dr. Tidy regards 400 cubic feet as the very smallest amount of space that should be allowed to each person in a sleeping room, to avoid serious over- crowding. Analysis shows that the foulest air in an occupied room is at the ceiling. The heat of the body or of a lamp causes an ex- pansion of the air about them, and an upward current of heated CO2, water vapor, etc. These gases reach the ceiling before they cool sufficiently to stop this upward current, and before there is time for perfect diffusion. The upper galleries in theatres are supplied with impure air from the main floor and lower galleries and from the gas lights. Fresh air should always be admitted to a room near the floor, and the outlet for impure air should be at or near the ceiling. It must be remembered that the law of dif- fusion of gases does not allow the CO2 to accumulate in one part of the room and remain there for any considerable time, but mixes it evenly through the air. Nor is this diffusion confined within a room. It takes place through porous walls between the indoor and outdoor air, especially in winter, when there is much difference in the temperature of the two. Indeed, a very fair amount of ventilation may be eff'ected in this way, where the walls are of brick or stone, and not painted or papered inside. Carbon dioxide exists in the blood partly in solution in the serum, partly combined as sodium bicarbonate, partly as sodium phospho-carbonate, and partly combined with the corpuscles of the blood. Putrefaction after COj poisoning is slow, while animal heat and rigidity are very persistent. 263. Tests for Carbon Dioxide. — If the quantity exceeds 12 per cent., a taper is extinguished. Lime water and baryta water absorb COj from the air, and are rendered cloudy by it, from the precipitation of the carbonates of calcium or barium. Advantage is taken of this fact to estimate the quantity of CO2 in air. A simple way of testing whether the air of a room contains too much CO2, is to select a quart bottle, fill it with the air of the room by first filling the bottle with water and pouring this out slowly. Now add to the bottle one cubic centimeter (n\,xvss) of clear and well saturated lime water, faintly colored with phenol-phthalein. Add a little pure water, cork, shake, and let stand for a few hours. Pure outdoor air contains just sufficient CO2 to decolorize the limewater. Indoor air should not decolorize more than 1.3 c.c. of lime water. CARBON. 209 264. Carbonic Acid and Carbonates. — COj is soluble in water, with which it combines to form carbonic acid, (H2CO3). H,0 + CO, = H,CO,. Carbonic acid is a feeble, dibasic acid, forming a double series of salts, the carbonates and acid- or bi-carbonates. As mentioned above, " soda water" is a solution of carbonic acid in water, kept under pressure. When the pressure is removed, a large portion of the acid undergoes decomposition into the anhydride, (COj), and water. The same decomposition, with effervescence, takes place when we prepare the acid by treating a carbonate with a stronger acid. The carbonates of gold, arsenic, antimony, and aluminium are unknown. The carbonates of the alkaline metals are soluble in water, and are not decomposed by heat J while the carbonates of all the other metals are insoluble, and are decomposed by heat, giving the oxides of the metals. The bicarbonates are formed by passing carbon dioxide through the solution of the carbonates. They are converted into the carbonates again by heat. The carbonates of ammonium are volatilized by heat. Water charged with carbonic acid dissolves the carbonates of some of the metals, as calcium, magnesium, iron, copper, lead, etc., which gives rise, in the case of the first two, to hard water. This hardness is deposited again on boiling the solution, or even on free exposure to the air, thus forming an important element in certain geological formations. 265. Carbon and Sulphur. — Carbon Disulphide (CS,) — Carbonei Disulphidum (U. S. P.) — is formed, like the di- oxide, by the direct union of the elements. When the vapor of sulphuris passed over charcoal heated to redness, the two elements combine, producing the vapor of carbon disulphide, which con- denses into a very volatile, colorless, mobile liquid, possessing a peculiar, disagreeable odor ; it refracts light strongly, and for this reason is used to fill hollow glass prisms for the spectroscope. It is combustible, burning with a blue flame, and has been sug- gested as a means of furnishing sulphurous oxide for fumigation, by burning a mixture of CSj and alcohol in a lamp. Sp. gr. 1.268 to 1.269 at 15° C. (59° F.). The vapor mixed with air, forms an explosive mixture, and mixed with nitrous oxide, it burns with a very brilliant flame. It is insoluble in water, but is miscible with alcohol and ether: It is a ready solvent for sulphur, phosphorus, caoutchouc (India rubber), fats, oils, and iodine, with the last of which it forms a violet-red solution. CSj dissolves in a solution of the alkaline 2IO MEDICAL CHEMISTRY. sulphides, forming sulpho-carbonates. CS^ + K2S = K2CS3. CSj may be regarded as the anhydride of sulpho-carbonic acid, HjCSa, obtained by adding hydrochloric acid to a sulpho-car- bonate. Pharmacopceial requirements : Carbon disulphide should not affect the color of blue litmus paper, moistened with water (absence of sulphur dioxide). It should leave no resi- due when evaporated spontaneously (absence of sulphur). Test solution of lead acetate should not be blackened when agitated with it (absence of hydrogen sulphide). Carbon Monosulphide (CS) — a brown-red powder, and a sulphide having the formula C5S2, and an oxy-sulphide, COS, are also known. 266. Carbon and Nitrogen. Preparation. — Although carbon and nitrogen cannot be made to unite directly, yet carbon compounds containing nitrogen, when heated with potassium hydroxide, yield potassium cyanide (KCN), and, in the presence of iron, form potassium ferrocyanide, or yellow prussiate of potash. From these two compounds all the long list of com- pounds containing the radical CN are prepared. Cyanogen is most easily prepared by heating mercuric or ar- gentic cyanide, or a mixture of two parts of well dried potassium ferrocyanide and three parts of mercuric chloride. 267. Properties, — Cyanogen is a colorless gas, possessing a pungent odor. It is soluble in one-fourth its volume of water, and one-twentieth its volume of alcohol. It is easily condensed to a liquid at — 20.7° C. ( — 5° F.), or at ordinary temperatures by a pressure of 4 atmospheres. At — 34° C. ( — 29.2° F.) it freezes to a snow-like solid. It burns in the air with a purple-red flame. The free cyanogen molecule is composed of two cyanogen radicals, CN — CN. The radical CN — (Symbol Cy) is a monad, negative, or acid radical, resembling the chlorine group in its chemical behavior, and forming, a series of cyanides resembling the chlorides, thus : — Potassium chloride, KCI. Potassium cyanide, KCy. Silver chloride, AgCl. Silver cyanide, AgCy. Mercuric chloride, HgCl^. Mercuric cyanide, HgCy,. 268. Hydrocyanic Acid — Prussic Acid (HCy) is most readily obtained by decomposing the metallic cyanides with sul- phuric or hydrochloric acid. KCy + HjSO, =HCy + KHSO,. AgCy + HCl = AgCl + HCy. aK^FeCy, + eHjSOj = FeK^FeCy, -|- eKHSO^ -|- 6HCy. CARBON. 211 The acid boils at 26.5° C. (79 7" F ), and is soluble in water, from which it gradually escapes It is a colorless liquid, of a characteristic odor and taste, resembling those of bitter almonds, the oil of which contains from 5 to 14 per cent, of this acid. It is also a constituent of laurel water. Acidum Hydrocyanicum Dilutum (V. S. P. and Br. P.) contains two per cent, of HCy, while the French Pharmacopoeia directs the acid to contain 10 per cent. Preparation. — The U. S. P. directs that potassium ferrocy- anide be treated in a retort with sulphuric acid and the resulting HCy distilled into a receiver containing some water. The pro- duct is then assayed, and diluted with distilled water to bring it to the strength of two per cent. A formula is also given for preparing the acid extemporaneously. Silver cyanide and hydro- chloric acid are shaken in a glass-stoppered bottle, and when the precipitate has subsided, pour off the clear liquid. 269. Cyanides. — Prussic acid forms a series of compounds known as cyanides, which resemble the haloid compounds. Like the acid, they are all more or less poisonous. The cyanides of potassium, mercury, and silver are best known. The first is soluble in water, the other two are insoluble. The potassium salt is used largely in photography and in electro-metallurgy. 270. Toxicology. — Hydrocyanic acid and the cyanides are very poisonous. One drop of the pure acid is enough to cause instant death. Accidents are liable to occur from the use of the cyanides, or from the acid or vegetable substances containing amygdalin, a body which easily undergoes decomposition into prussic acid and other products. Bitter almonds, cherry-laurel, the pits of the common cherry, plum, peach, and sloe, may be mentioned as the most common of these. In England, poison- ing by cyanides ranks second in order of frequency in all cases of poisoning. One grain of HCy and 2.4 grains of potassium cya- nide are sufficient to cause death in man. The symptoms of poi- soning by HCy and KCy are very nearly the same — first a saliva- tion, then constriction of the throat, giddiness, and insensibility. The person then falls, usually in a convulsion, respiration and pulse become irregular, and finally cease. The symptoms com- mence from ten seconds to one minute after swallowing the poison, depending somewhat upon the dose and form of admin- istration. In some cases death is almost instantaneous ; in others, it is prolonged to 15 minutes, or longer. Hydrocyanic acid enters the blood, forming a compound with the haemoglobin, passes to the medulla, and paralyzes the respiratory centres. The 212 MEDICAL CHEMISTRY. post-mortem appearances are mainly those of suffocation, and everywhere there is the odor of the acid, unless concealed by putrefactive odors. When potassium cyanide has been used, there is usually inflammation of the stomach, due to its caustic action. 271. Chronic Poisoning by Cyanides may occur in pho- tographers, gilders, and electro-platers. The symptoms are head- ache, giddiness, noises in the ears, pains in the region of the heart, difficult respiration, loss of appetite, nausea, obstinate con- stipation, full pulse, pallor, and offensive breath. 272. Treatment. — When there is time, cold douches, ammo- nia mhalations, chloride of lime, alone or moistened with vinegar and held to the nose, friction, electricity, artificial respiration. The best antidote is a mixture of ferrous and ferric sulphates, with sodium or potassium hydroxide or carbonate. Usually, however, there is not sufficient time to apply these remedies, ex- cept in cases of poisoning by the vegetable substances above mentioned as containing it, and in chronic poisoning. 273. Tests. — ist. Silver nitrate precipitates the acid as silver cyanide — a white, curdy precipitate, insoluble in nitric acid. A glass rod moistened with AgNOa and held in the vapor is rendered milky. 2d. Add a solution of liquor potassse, or potassium hydroxide, then a solution of ferrous sulphate mixed with ferric sulphate, then a small quantity of sulphuric acid, when a blue deposit of Prussian blue will appear. 3d. To a small portion of the suspected liquid, in a wide test tube or crucible, add dilute sulphuric or hydrochloric acid. Invert over this a watch glass, convex side down, with one or two drops of yellow ammonium sulphide upon the under side of it. Warm the crucible gently, and after a few minutes remove the watch glass, warm, and evap- orate the ammonium sulphide by blowing upon it. Now touch the stain with a drop of ferric chloride, when a blood-red slain will make its appearance, due to the formation of sulpho-cyanate of ammonium on the glass, which, with the iron, strikes a red color. This is easy to perform, is applicable to organic mixtures, and is quite delicate. Assay. — Mix in a flask of about 100 c. c. capacity, 0.270 gm. of the HCy to be tested, wilh a little water, and enough magnesia to make the mixture opaque. Add to this two or three drops of test solution of potassium chromate, and then from a burette silver nitrate solution until a permanent red tint is pro- duced. Each CO. of the silver nitrate solution used represents I per cent, (or 0.0027 g™') of ptire HCy, CARBON. 21 J 274. Cyanic Acid (H-O-Cy). — Metallic cyanides readily take up oxygen, when fused with potassium nitrate or even the oxides of some of the metals, and form cyanates. The acid, HOCy, maybe prepared by decomposing its salts with dilute acids. It is unstable, and breaks up into carbon dioxide and ammonia. HOCN + HjO = NH3 + CO2. Of the cyanates, the ammonium cyanate is the most interesting, as its solution in water, on being heated, forms urea, a body isomeric with it, and a well known excretory substance found in urine. NHjCNO = COlNHj),. This is interesting as being the first animal substance prepared by synthesis. 275. Sulphocyanates — The potassium salt is prepared by fusing potassium ferrocyanide and sulphur together, and ex- hausting the fused mass with alcohol. On evaporating the alco- hol, a white, crystalline salt is obtained, soluble in water, and having the formula KSCy. Ammonium Sulphocyanate (NHiSCy) is prepared by heating hydrocyanic acid with yellow ammonium sulphide. The principal interest attached to these salts is as tests for ferric iron salts, with which they give a blood-red solution. The sodium salt is found in traces in human saliva. Mercuric sulphocyanate, formed by precipitating mercuric nitrate with potassium sulphocyanate, is decomposed by heat, the mass swelling up and leaving a voluminous residue. It is used in making the toy, Pharaoh's Serpents. 276. Compound Cyanides. — Cyanogen shows a remarkable tendency to form complex compounds. Among these more complex compounds are two series of bodies in which cyanogen and iron form the radical. Of these, the ferrocyanides and ferricyanides of potassium and iron will be mentioned here. Potassium Ferrocyanide — K4(FeCy6) — Yellow Prus- siate of Potash, is an important commercial product, manu- factured on a large scale by fusing in a closed crucible nitro- genous animal matter (horns, hoofs, leather scraps, etc.) with potassium carbonate and iron filings, treating the fused mass with water, and crystallizing. The salt is thus obtained in large, yellow, tabular crystals. It is used in dyeing, in preparing cer- tain pigments, and as a source of all the other cyanogen com- pounds. By simple fusion, potassium cyanide (KCy) is prepared. 214 MEDICAL CHEMISTRY. K.FeCy, = 4KCy + FeC, + N,. From a solution of the salt, various other ferrocyanides are pre- pared by precipitation. Of these, Prussian Blue (ferric ferro- cyanide), prepared by adding to a solution of potassium ferro- cyanide a solution of some ferric salt, is used as a pigment and as a medicine. With a ferrous salt the precipitate is white, but quickly becomes blue by oxidation. This test serves to distinguish ferrous from ferric salts. With cupric salts we obtain a reddish- brown precipitate, CuaFeCys- Ferricyanides. — By passing chlorine through a solution of K4FeCy6, a compound is formed in which the iron of the radical is tetrad, and the radical itself becomes hexad. KsCFejCyu)"^. On evaporating, we obtain dark red crystals of potassium ferricyanide, or red Prussiate of potash. With ferrous salts a solution of this salt gives a deep blue precipitate of ferrous ferricyanide — FesFe^Cyu — TurnbuU's Blue. Ferric salts give no precipitate or coloration, and thus we distinguish ferric from ferrous salts. Ferric Ferrous cyanide ^ Prussian Blue. Ferrous Ferric cyanide = TurnbuU's Blue. The further consideration of carbon compounds will be found in Part IV. SILICIUM— SILICON. 277. Occurrence. — In native rocks, either as silicic oxide (SiOj), quartz, amethyst, carnelian, etc., or combined with various metallic oxides as silicates. Clay is principally a silicate of aluminium colored with iron and vegetable matter. This, next to oxygen, is the most abundant of the elements. Neither the element nor its compounds are of much interest to medical students. The element never occurs native, and may be prepared in three allotropic states : — amorphous silicon, graphitic sili- con, and crystallized silicon, somewhat resembling the three states of carbon. 278. Compounds. — Silicic Hydride (SiHi") is obtained as a colorless, spontaneously inflammable gas, by the electrolysis of a solution of common salt, using for the positive electrode an aluminium containing silicon. Silicic chloride (SiCl^) is a colorless, volatile liquid possessing an irritating odor. The TIN. 2 IS bromide, SiBri, and fluoride, SiFI,, are also known. This latter is decomposed by water, forming hydro-fluo-silicic acid, H,F,Si. 279. Silicic Oxide, or Anhydride (SiOj), is the only known oxide of this element, and exists in a pure state in quartz crystal. It may be prepared artificially by adding hydrochloric acid to a concentrated solution of soluble or water glass, filtering, wash- ing, and heating the residue to expel the water. Artificially prepared, it is a fine, white, tasteless powder, fusible with great difficulty, and not sensibly soluble in water or acids, with the exception of hydrofluoric acid. Its sp. gr. is 2.66. When fused with potassium or sodium carbonates or hydroxides, it forms a silicate of these metals, or glass ; when these alkalies are in excess, the glass is soluble in water, the degree of solubility increasing with the proportion of alkaline salt used. This com- pound is known as soluble or -water glass. 280. Silicic Acid and Silicates. — The normal silicic acid has the formula HiSiOi, and is only known in solution in water. It may be prepared by adding hydrochloric acid to a very dilute solution of an alkaline silicate, but it is unstable. The acid is very prone to liberate a portion of its water and form acids of the condensed types ; /. e., two or more molecules unite and lib- erate one or more molecules of water. The native silicates are very complex in structure, and are usually formed on this con- densed plan. 281. Glass. — Common glass is a mixture of several silicates, in which there is an excess of silica ; the principal ones used being sodium, calcium, and lead silicates. By the addition of small quantities of metallic oxides, various colors are imparted to the glass ; thus, cobalt gives a blue, manganese an amethyst, cuprous oxide a ruby, and cupric oxide a bluish-green, chromium a greenish-yellow, ferric oxide a brownish-yellow or black, ferrous oxide the ordinary green bottle glass. The element Germanium is not of sufficient interest to merit an extended description here. TIN (Stannum). Sn = ii8. Sp. gr. = 7.3. 282. Occurrence. — Tin was known before the Christian era. It is said to have been found native. The chief ore is cassiter- ite, or tin stone, SnO,. The metal is not abundant and the mines are but few ; those of Cornwall and Banca are best known. 2l6 MEDICAL- CHEMISTRY. Commercial tin is seldom pure, but is liable to contain lead, copper, iron, zinc, antimony, or arsenic. 283. Properties and Uses. — Tin is a bluish-white, soft metal, malleable, ductile, fusing at 220° C. (446°F.). At 100° C. (2i2°F.) it may be drawn into wire, but at 200° C. it is so brittle that it may be pulverized. It oxidizes readily when in the melted state, and at higher temperatures it takes fire and burns to SnOj. At ordinary temperatures it is fairly permanent in the air. It dissolves in hot hydrochloric acid and in dilute nitric acid, and in hot concentrated solutions of sodium and potassium hydroxides. As tin does not tarnish in air, or is not easily attacked by the organic acids, it is much used to prepare culinary vessels. Owing to its cost and brittleness it is usually employed to coat over sheet iron and copper. Ordinary sheet tin is sheet iron covered with tin by immersing the previously cleansed iron in a bath of melted tin. To prevent the oxidation and waste of the tin while in the melted state, it is covered with a layer of melted tallow. The article to be tinned is dipped through the tallow into the melted tin, thence into another bath of tallow to allow the excess of tin to run off. An alloy of tin and lead is largely used for tinning iron and copper, to cheapen the cost. This alloy is corroded by ordinary water, and should never be used for culinary vessels or for canning vegetables or fruits, on account of the lead. Brass and copper articles may be given a thin layer by immersing them in a boiling solution of tin chloride in contactwith pieces of metallic tin. Mirrors are coated with an amalgam of tin in such a way as to exclude all air. The ordinary tin foil, used as wrap- ping material, is made by rolling a sheet of lead between two sheets of tin. 284. Compounds. — Tin forms two classes of compounds corresponding to the dyad and tetrad conditions respectively. Of these the most important are the following : — Stannous Stannic Compounds. Compounds. Chlorides, SnCl,. SnCl^. Oxides SnO. SnO^. Hydroxide Snp(0H)2. . . . Acids HjSnOj. Metastannic Acid HjoSn^Ois. Clilorostannic HjSnClj. Nitrate Sn(N03^2 Sn(N03)j. Sulphate, SnSOj. Sn^SO^jj. Sulphide, SnS. SiiSj. LEAD. 217 Of these compounds the most important is stannous chloride, SnClj. It is prepared by treating tin with dry HCl, or mercuric chloride. When tin is dissolved in HCl and the solution is evaporated down and cooled, it deposits crystals of SnCl2.2H20. These crystals dissolve in about one-third their volume of water, but are decomposed by a large quantity of water into a basic salt. When the solution of this salt is exposed to air, it absorbs, oxygen and deposits an oxychloride. Stannous chloride is a strong reducing agent, and is used as such in the laboratory. It is used in dyeing as a mordant. Hydrated stannous sulphide is produced as a brown powder when HjS is conducted through a solution containing a stannous salt. It is insoluble in dilute acids, but soluble in alkaline sulphides. Stannous oxide occurs native in the mineral cassiterite. When prepared artificially, by roasting tin or the hydroxide, it appears as a white powder. It is used in the manufacture of opaque white glass. Stannic oxide is used as a polishing powder under the name of " putty powder." The tin salts have found little use in medicine. 285. Toxicology. — The salts of tin have feeble toxic proper- ties. The chlorides are poisonous, belonging to the irritant poisons. As the chlorides are used in dye works, they have been taken by mistake and have caused death or serious symp- toms. The symptoms do not appear to be constant or uniform, but there is usually vomiting, pain, depression of the heart's action, diarrhoea, and delirium. The treatment is to encourage vomiting and give milk freely. Ammonium carbonate may be given, which precipitates the tin in a comparatively insoluble and inert condition. The chlorides are decomposed by nearly all the animal fluids, and also by vege- table infusions. The effects of small doses of tin continued for a long time have not been clearly defined. LEAD (Plumbum). Pb — 207. 286. Occurrence. — The most abundant ore found native is Galena, or Galenite (PbS). Other ores are Cerussite (PbCOa), Crocoisite (PbCrOi), Wulfenite (PbMoO^), and Pyromorphite (PbsCPOA). 287. Preparation. — For this purpose galenite is almost exclusively employed. The ore is first roasted in the air, by «9 2l8 MEDICAL CHEMISTRY. which a portion of the lead sulphide is converted into oxide, and another part into sulphate. 2PbS + 30j = 2PbO + 2SOj and 2PbS + 4O2 = 2PbS04. These two products are then strongly heated in a reverberatory furnace, when they react as follows : — 2PbO + PbS = 3Pb + SOj and PbSOj + PbS = 2Pb + 2SOj. If the galena contains much silver, this is separated by crystalliza- tion and cupellation. 288. Properties. — Lead is a bluish-white metal, brilliant upon freshly cut surfaces, but soon tarnishes. It is soft and pliable, but not very malleable or ductile ; specific gravity 1 1 .37. It fuses at 334° C. (633° F.). It is a poor conductor of elec- tricity, but a better conductor of heat. When exposed to the air, it oxidizes slightly. It is not acted upon by pure water deprived of air, but, by the contact of air and water, it oxidizes to the hydroxide (Pb(0H)2), which is slightly soluble in water. If the water contains carbon dioxide, carbonates, or sulphates, very little lead goes into solution, but it is coated with an insoluble layer of lead carbonate or sulphate. If the carbon dioxide be under pressure, as in soda water, the carbonate formed is somewhat soluble in the water. The solvent action of water upon lead is increased, however, by the presence of nitrates and nitrites. These facts are of great practical importance, as lead pipes are very frequently employed for conducting potable waters. Sulphuric and hydrochloric acids have but little effect on lead, especially if cold, owing to the insolubility of its sulphate and chloride. Nitric acid dissolves it readily. Zinc, tin, and iron precipitate this metal from its solution. There are several useful alloys of lead. Alloyed with an equal part of tin, it fuses at 186° C. (366.8° F.) and is used for soft solder. Type-metal is an alloy of four or five parts of lead and one of antimony ; the proportions vary considerably. 289. Lead Chloride (PbClj) separates as a white precipitate when hydrochloric acid is added to a concentrated solution of a lead salt. It is nearly insoluble in cold water, but dissolves in thirty parts of hot, from which solution it crystallizes, on cooling, in white, shining needles. At a red heat it fuses to a horn-like mass. LEAD. 219 290. Lead Iodide— Plumbi lodidum (U. S., Br.), (Pbl^) — is precipitated from lead solutions by potassium iodide, as a bright yellow, crystalline powder. It is practically insoluble in cold water, but more soluble in boiling water, from which it crystallizes, on cooling, in beautiful, gold colored, glistening crystals. An ointment of this salt is official. Exposed to light and moisture, it decomposes, with liberation of iodine. 291. Lead Oxide — Protoxide — Massicot — Litharge — Plumbi Oxidum (U. S., Br.), (PbO) — is prepared by heating lead, its carbonate or nitrate, in the air. Much of it is obtained as a bye-product, in the extraction of silver from galena. If it fuses, it constitutes litharge ; if not, massicot. The former is a reddish -yellow or brown mass of rhombic scales ; the latter is a yellow, amorphous powder, differing from litharge in color and texture but not in composition. Lead oxide has strong basic properties. It absorbs carbon dioxide from the air and imparts an alkaline reaction to water, in which it dissolves as hydroxide. Like other strong bases, it saponifies fats when heated with them, to form lead soaps, as lead plaster. It dissolves readily in nitric or hot acetic acid, with formation of nitrate or acetate of lead. It fuses at a red heat. If fused in earthen crucibles, it attacks the crucible and forms a silicate, and thus perforates the crucible. When heated to 300° C. (572° F.) in contact with air, it is slowly oxidized to a bright red powder, minium, or red lead. 292. Plumboso-plumbic Oxide — Minium — Red Lead (PbsO^) or (aPbO.PbOj) — is prepared, as already stated, by roasting litharge at a temperature of 300° C. (572° F.), and is used as a pigment and in the manufacture of glass. Its compo- sition is probably expressed by the formula PbsO, ; or, as one molecule of the dioxide combined with two of the monoxide ; or, as the lead salt of plumbic acid. It is a brilliant red powder, of specific gravity 8 62. When strongly heated, or subjected to the action of reducing agents, it is converted into litharge. Nitric acid dissolves the monoxide, leaving the dioxide, the color changing to brown. As occurring in commerce, it is frequently contaminated with oxides of iron or brickdust. It should dissolve in dilute nitric acid to which a little sugar has been added. 293. Lead Dioxide — Peroxide of Lead— Puce Oxide of Lead — Binoxide of Lead — Plumbic Anhydride— may be prepared by dissolving the monoxide out of mmium with di- 220 MEDICAL CHEMISTRY. lute nitric acid, or by the action of clilorine upon lead carbonate suspended in water. It is a dark, reddish-brown powder, insoluble in water ; spe- cific gravity 8.903 to 9.190. Heat drives off half its oxygen, converting it into monoxide. It is therefore a valuable oxidiz- ing agent when heated. 294. Plumbic Acid is formed as crystalline plates at the posi- tive electrode, when alkaline solutions of the lead salts are sub- jected to electrolysis. With the alkaline hydroxides, lead dioxide dissolves to form well defined but unstable plumbates. Potassium plumbate may be obtained in cubic crystals by dissolving the hydroxide in potassium hydroxide, and cooling the solution. It is decomposed by water. 295. Lead Nitrate— Neutral Lead Nitrate — Plumbi Nitras (U. S., Br.), (Pb(NOs)2) — is obtained by dissolving lead or its oxides in excess of nitric acid. PbO + 2HNO3 = Pb(N03)2 + HP- It forms anhydrous octahedral crystals, soluble in 2 parts of water at 15° C. (63.5° F.) and 0.7 part at 100° C. (212° F.). At a red heat, it melts and is decomposed into PbO, NO2, and oxygen, and at a higher temperature into PbO. 296. Lead Sulphate (PbSO^) occurs in the mineral Anglesite in rhombic crystals, isomorphous with barium sul- phate. It is produced by the double decomposition between a sulphate and a soluble lead salt. Pb(N03)j + Na2S04= PbSO, + 2NaN03. It is insoluble in water, but readily soluble in concentrated sul- phuric acid. The commercial acid always contains it. 297. Lead Carbonate (PbCOj) occurs as Cerussite. Plumbi Carbonas (U. S. P.) has the composition (PbC03)2Pb- (0H)2. It may be produced by double decomposition between a lead salt and a soluble carbonate, or by passing carbon dioxide through a neutral Solution of lead salt. White lead is usually prepared commercially by treating thin sheets of lead with acetic acid and then exposing the acetate to carbon dioxide. The lead, rolled into sheets, is placed in earthen jars containing a small quantity of vinegar at the bottom but not in contact with the lead. Great numbers of the jars after being thus charged are buried in stable manure or spent tan bark. By the decomposi- tion of the bark or manure, considerable carbon dioxide and heat are produced. The heat volatilizes a portion of the vinegar, which, acting upon the lead, produces the acetate (Pb(C2H302)2). The carbon dioxide acting upon the acetate converts it into acetic acid, which acts upon a fresh portion of the lead, and a basic or hydro-carbonate of lead having the formula: — (PbCOa), Pb(OH)j, or PbO— HCO3— Pb-COj— PbO— H. After the lapse of a considerable time, about six weeks, the pile is taken down, the sheets are taken out, and the carbonate de- tached from them by passing them through rollers or by pound- ing. The' white powder is then ground with oil and sent into the market as " White Lead." White lead is largely used in oil painting, forming a part of all but the darkest colors. As it is poisonous, and is darkened by the action of hydrogen sulphide in the atmosphere, it is at present being more and more replaced by zinc white (ZnO) and permanent white (BaSO,). 398. Lead Sulphide (PbS) occurs in the mineral galena. It IS precipitated from a solution of lead salts by hydrogen sul- phide, or alkaline sulphydrates, as a black powder. The native sulphide is bluish-gray and has a metallic lustre ; sp. gr. 7.58. The sulphide obtained by precipitation has a sp. gr. of 6.924. It is insoluble in dilute acids. 299. Lead Acetates-Salt of Saturn — Sugar of Lead — Plumbi Acetas (U. S., Br.), (Pb(C2H302X).3H2O— is pre- pared by dissolving litharge in acetic acid ; or by exposing lead to the action of acetic acid and air, evaporating and crystal- lizing. It forms large oblique rhombic prisms, having a sweetish, metallic taste. It dissolves in 2.3 parts of water at 15° C. (59° F.) and in 21 parts of alcohol, forming solutions which react acid upon test paper. On exposure to the air, the crystals effloresce upon the surface and are partly converted into carbonate. Several subacetates, or basic acetates, are known. The only one requiring mention is that having the formula, approximately, of PbjOCCjHaOjlj. This is the chief constituent of Liq. plumbi subacetatis (U. S., Br.) or Goulard's extract, which is obtained by boiling a solution of the neutral acetate with lead monoxide in fine powder. When exposed to the air, this solu- tion absorbs COj and becomes milky, from the formation of lead carbonate. 300. Lead Chromate (PbCrOJ is formed by precipitating lead nitrate or acetate with potassium chromate. Pb(N0,)2 + K^CrO, = PbCrO, + 2KNO3. 2 22 MEDICAL CHEMISTRY. It is used as a pigment, under the name of chrome yellow. Recently, its fraudulent use as an artificial coloring agent in man- ufactured food products has been discovered. It is insoluble in water, but soluble in strong alkalies. 301. Physiological Action of Lead. — All of the com- pounds of lead that are soluble, and those that are themselves insoluble but that are readily convertible into soluble com- pounds by the action of air, water, or the digestive fluids, are poisonous. The chronic form of lead poisoning, painter's colic, is very common, and is produced by the continuous absorption of small quantities of the metal or its compounds, either by the skin, lungs, or stomach. Although metallic lead is inert, its absorp- tion will cause symptoms of poisoning from its being converted within the body into poisonous compounds. Some of the methods by which it may be introduced are, the drinking of water that has been in contact with the metal ; the use of food, tobacco, etc., that has been wrapped in tin-foil containing lead ; the drinking of beer or other beverages that have been kept in pewter vessels ; the handling of the metal, its salts, or its alloys by artisans. Almost all of the commoner compounds of lead may give rise to chronic poisoning. Probably the carbonate is the cause of more cases than any other lead compound in painters, artists, manufacturers of paint, and persons sleeping in freshly painted apartments. Acute lead poisoning is comparatively rare and is not often fatal. It is generally caused by the ingestion of a single large dose of the acetate, subacetate, carbonate, or red lead. When it occurs, magnesium sulphate should be given, as it forms an insoluble lead sulphate. If the metal be once absorbed, it is eliminated slowly, as it tends to become fixed by combination with the albuminoids of the body. This combination is rendered soluble by potassium iodide. It is eliminated by the urine, perspiration, and bile. On account of the many ways that it may be introduced, great caution is necessary in drawing conclusions from traces of lead found in the body after death. 302. The Remaining Metals of Group IV are titanium, zinconium, cerium, and thorium. Of these the only one that has found use in medicine is cerium. Cerium is a somewhat rare metal found in a number of minerals, more especially in cerite, as a silicate. The element may be obtained by electrolysis of cerous chloride. It resembles LITHIUM. 223 iron in most of its physical properties. It forms two series of compounds, like iron. The oxalate Ce3(C204)s + pHjO is used in medicine, and is prepared by precipitating cerous chloride with ammonium oxalate. It is a white powder, permanent in air, odorless, taste- less, insoluble in water or alcohol, but soluble in hydrochloric acid. On heating the salt it decomposes, leaving a reddish yellow residue of Ce^Os. GROUP I.— THE ALKALI METALS. 1. Lithium 7 4. Rubidium, .... 85 2. Sodmm, 23 5. Caesium 133 3. Potassium 39 6. (Ammonium), NHj=i7 303. The metals of this group present great similarity in their chemical and physical properties. Exposed to the air, they all oxidize readily. They decompose water violently, with the forma- tion of strong basic hydroxides which dissolve in the excess of water. The hydroxides thus formed are called caustic alkalies (caustic potash, caustic soda) ; hence the name, alkali metal. Nearly all of the salts of these metals are soluble, and most of them, when in solution, turn red litmus blue. They form but one chloride, one iodide, and one bromide. LITHIUM. 304. Lithium occurs widely distributed in nature, but in small quantities. It is found in some mineral springs and in the ashes of many plants, chiefly that of tobacco and beet. It is usually obtained by separating it from its chloride by electrolysis. It is silver-white in color, and decomposes water at ordinary tempera- tures. It is the lightest of the solid elements, and floats upon naphtha. Sp.gr. 0.589. It fuses at 180° C. (356° F.), and burns in air with an intense red light. Its salts closely resemble those of sodium. 305. Lithium Chloride (LiCl) crystallizes at ordinary tem- peratures, in regular, anhydrous octahedra; below 10° C. (50° 2 24 MEDICAL CHEMISTRY. F.), however, with two molecules of water. It is very deliques- - cent. Lithium Bromide — Lithii Bromidum (U. S. P.), (LiBr) — is obtained by decomposing lithium sulphate with potas- sium bromide; or, by neutralizing a solution of hydrobromic acid with lithium carbonate. It crystallizes in deliquescent needles. Soluble in 0.6 part of water at i5°C. (59° F.) and 0.3 parts of boiling water. Very soluble in alcohol and ether. Lithium Oxide (LizO) is a white solid, formed by burn- ing lithium in dry oxygen. It slowly dissolves in water, forming the hydroxide, LiOH. 306. Lithium Carbonate — Lithii Carbonas (U. S. P.) (L12CO3) — is obtained by fusing a native silicate called lepido- lite, with. barium sulphate and carbonate, and potassium sulphate. It is then extracted with water, and precipitated with sodium carbonate. It is a white, odorless powder, of a strongly alkaline taste, soluble in 80 parts of water at 15° C. ("59° F.), and in diluted acids with copious effervescence. It unites readily with uric acid, forming a soluble lithium urate. It is said that 250 parts of lithium carbonate at a temperature of 38° C. (100.4° F.) will dissolve almost 1000 parts of uric acid. This property renders it of value, in diminishing the deposit of uric acid formed in gout, and in dissolving uric acid calculi. Lithii Benzoas (LiCjHsOj) (U. S. P.) is a light, white powder, having a faint benzoin-like odor, and a sweetish taste ; it is soluble in 4 parts of water and in 12 parts of alcohol. Its aqueous solution has a faintly acid reaction upon litmus paper. Lithium Citrate (UsCeHfi^) (U. S. P.) is a white, odor- less, deliquescent powder readily soluble in water, almost insol- uble in alcohol. It is made by double decomposition between LijCOs and citric acid. 3Li.,C03 + aHjCeH^O, = 2Ufi^Hfi, + 3CO, + sH.O. Lithium Salicylate (LiC,H503)(U. S. P.) is made by double decomposition between lithium carbonate and salicylic acid. Li,C03 + 2UC,Ufi, = 2UC,Hfi, + CO2 -t- Ufi. A white, deliquescent, odorless powder, having a sweetish taste. It is very soluble in water and alcohol. SODIUM. 225 SODIUM (Natrium). Na = 23. 307. Occurrence. — This metal occurs widely distributed, being found in sea-water and in rock salt, as chloride, and in many native silicates, also in borax and glauber salt. Preparation. — It is obtained by a process which depends upon the reduction of the carbonate by carbon. An inti- mate mixture of the two substances is prepared by charring the tartrate of sodium in an iron retort. The temperature is now raised to redness, when the sodium is reduced, distils off, and is condensed in flattened receivers. Na,C03 + C,= Naj + 3CO. Properties. — Sodium is a soft, silver-white metal, resem- bling potassium, but less easily oxidized. It becomes slowly coated with a brownish-yellow layer, on exposure to the air, and should be kept under naphtha. It fuses at 95.6° C. (203.8° F.), and volatilizes at a white heat, the vapor burning with a bright yellow flame. Sp. gr. 0.972. It is characterized by its affinity for oxygen, decomposing water at ordinary temperatures, libera- ting hydrogen, and forming sodium hydroxide, NaOH. Na, + 2H2O = 2NaOH + H^. 308. Sodium Chloride — Common Salt — Sodii Chlori- dum (U. S., Br.), (NaCl) — is found very abundant in nature. It is deposited in almost all parts of the globe, in the solid form, as rock salt ; in solution, it is found in all natural waters, and to the extent of 2.7 to 3.2 per cent, in sea water; it also exists in most animal and vegetables tissues. It is formed in a great number of chemical reactions. Its most important source is the deposits of rock salt, from which it is mined ; it is also obtained by the evaporation of sea water or saline spring waters. It crystallizes from water in translucent cubes. It fuses at a red heat, and volatilizes at a white heat. Hot water dissolves but little more than cold ; 100 parts of water at 0° C. (32° F.) dissolve 36 parts of the salt, and at 100" C. (212° F.) 39 parts. A saturated solution, therefore, contains 36 per cent, sodium chloride. From dilute solutions, nearly pure ice is obtained by freezing. On account of a slight admixture of magnesium salts, most specimens of common salt will deliquesce ; the perfectly pure salt, however, is not hygroscopic. 309. Sodium Bromide (Na Br) (U. S. P.) is formed, together with sodium hypobromite, by the action of bromine 226 MEDICAL CHEMISTRY. upon a solution of sodium hydroxide.. The hypobromite is converted intobromate upon evaporating the solution to dryness. SBrj + 6NaOH = SNa Br + Na BrOj + 3H2O. The mixture of Na Br and Na BrOj, is then heated with char- coal, which converts the Na BrOj into Na Br. 5Na Br + Na BrOj + 3C = 6Na Br + 3CO. It crystallizes in anhydrous cubes, and is soluble in 1.13 parts of water at 20° C. (68° F.), and in 0.87 at 100° C. (212° F.). It contains 77.67 per. cent, of bromine. 310. Sodium Iodide (Nal) (U. S. P.) is made by the action of iodine upon a hot solution of sodium hydroxide. 3I2 + 6Na OH = sNal + NalOg + 3H2O. The solution is evaporated, and the salts are then heated in contact with charcoal, and the NalO., reduced to Nal. SNal + NalOs + 3C = 6NaI + 3CO. It crystallizes in cubes without water, and is soluble in 0.56 part of water at 20° C. (68° F.), and in 0.32 at 100° C. (212° F.). It contains 84.66 per cent, iodine. 311. Oxides. — Two are described — NajO, NajOj. The first of these is a white powder, formed by the oxidation of the metal in dry air. It is very deliquescent, soon liquefying in air. The peroxide, Na^O.^, is a grayish-white mass, obtained by burning sodium in a current of oxygen. They both unite with water with great energy. 312. Sodium Hydroxide — Sodium Hydrate — Caustic Soda— Soda (U. S. P.) (NaOH)— is usually obtained by boil- ing a solution of sodium carbonate with calcium hydroxide. Na^COs + Ca {OH)^ = CaCOj + 2NaOH. The resulting solution, after filtering, is evaporated to dryness, dissolved in alcohol, again evaporated, fused in a silver vessel, and cast into sticks. This product is usually labeled caustic soda, by alcohol. It is a white, opaque, brittle, crystalline mass, or in dry white pencils, fusing below redness ; sp. gr. 2.00. It dissolves readily in water, the solution being known as soda lye in the arts, and in pharmacy as liquor sodae (sp. gr. of latter 1.059). This solution attacks glass; hence, the necks and stoppers of bottles containing it should be coated with SODIUM. 227 paraffin. When exposed in the air, sodium hydroxide attracts water and carbon dioxide, liquefies, and is converted into the carbonate. 313. Sodium Sulphate— Neutral Sodium Sulphate — Glauber's Salt— Sodii Sulphas (U. S. P.)— Sodse Sulphas (Br.) (NajSO^.ioHjO) — occurs native in deposits; also in solution in mineral waters. It is a by-product in the manufac- ture of sodium chloride from sea water and brine, and in several manufacturing industries. It is prepared by the decomposition of common salt with sulphuric acid. 2NaCl + H^SOi = NajSO^ + 2HCI. Sodium sulphate crystallizes, at ordinary temperatures, with ten molecules of water in large, colorless, monoclinic prisms, which effloresce in the air, losing all of their water. If heated to 33° C. (91.4° F.) it liquefies in its own water of cr)'Stalli- zation, and at higher temperatures becomes anhydrous. At 12° C. crystals may be obtained having the formula NajSOi. 7H2O. The following curious action of tlie solution of Glauber's salt may also be noticed. If the solution, saturated at 33° C. (91.4° F.), be cooled down to the ordinary temperature, and even far below, no separation of crystals occurs, although the salt is very much less soluble at lower temperatures than at 33° C. (91.4 F.). This formation of a supersaturated solution is common to many salts, though not to so marked a degree as in the case of Glauber's salt. This supersaturated solution may be agitated, and still no crystals form. But, if it be gently touched with a glass rod or some other solid body, the entire mass will at once become crystallized. 314. Hydro-Sodium Sulphate — Acid Sodium Sulphate — Sodium Bisulphate (NaHSO^) — is obtained by the action of an excess of sulphuric acid upon sodium sulphate, or sodium chloride. NaCl + H2SO4 = NaHSOj + HCl. It crystallizes in long, four-sided prisms. It fuses readily, and at higher temperatures loses water and is converted into the pyrosulphate Na2S20,. Very soluble in water, giving an acid solution. 315. Sodium Thiosulphate — Sodium Hyposulphite (NajSjOs) — is prepared by boiling the sulphite with sulphur. Na^SOa + S = Na^SjOj. The sulphite— sodii Sulphis (U. S. P.) (Na^SOa),— is pre- pared by saturating one half of a solution of NajCOa with sulphur- 2 28 MEDICAL CHEMISTRY. ous oxide and adding the other half. The SOj converts the carbonate into the hydrogen sodium sulphite, HNaSOs. Na^COj + H2O + 2SO2 = 2NaHS03 + CO^. This salt reacts with sodium carbonate to produce the sulphite. 2HNaS03 + Na^COj = 2NajS08 + H^O + COj. Sodium hyposulphite forms large monoclinic prisms, which contain 5 molecules of water, and is slightly deliquescent in the air. It is used as a reducing agent, decolorizing an iodine solu- tion with the formation of sulphuric acid and sodium iodide. Sodium Bisulphite is official. It is made by passing SO2 into a solution of sodium carbonate, evaporating, and crystal- lizing. 316. Sodium Carbonate — Soda — Neutral Carbonate of Soda— Sal Soda— Washing Soda — Sodii Carbonas (U. S. P.) — Sodae Carbonas (Br.P.) (NajCOs) — is the most import- ant of the sodium compounds for industrial purposes. It occurs abundantly in nature, in the so-called sodium seas (in Egypt, and the Caspian Sea), and is contained in the ashes of many sea plants, chiefly the algae. The principal supply is sodium chloride, from which it is manufactured according to a method devised by Leblanc in 1808. By this method the sodium chloride is first converted into sulphate by warming with sulphuric acid. This part of the process is called the salt cake process. The sul- phate, when dried, is mixed with charcoal and calcium carbonate, and strongly heated. Two reactions take place during this pro- cess : First, the carbon reduces the sodium sulphate to sulphide. Na^SO^ -I- Cj = NajS + 2C02. Second, the sodium sulphide and calcium carbonate react to form calcium sulphide and sodium carbonate. This is known as the soda ash process. Na^S + CaCOs = CaS -f NajCOj. The high temperature also converts a portion of the calcium carbonate into calcium oxide and carbon dioxide. The products of this fusion, known as black ball soda, are, therefore, sodium carbonate, calcium sulphide, and calcium oxide. The black ball is broken up and lixiviated with hot water, which dissolves out the sodium carbonate; this solution is evaporated to dryness, and crude soda ash, or soda of commerce, results. Of late years another process, known as Solvay's, or the am- monia method, has largely replaced that of Leblanc. In this SODIUM. 229 process, a strong solution of sodium chloride is treated at the same time with ammonia gas and carbon dioxide, NaCl + NHj + CO2 + H2O = NaHCOj + NH^Cl, forming the sparingly soluble sodium bicarbonate and the freely soluble ammonium chloride. The sodium bicarbonate is then con- verted into the carbonate by heat. The carbonate is also largely made by the Cryolite Process. Cryolite is a mineral found in great abundance in Greenland ; it is a double fluoride of alumi- nium and sodium. 6NaF. A\ Fj. This is heated with lime (CaO), which decomposes it, forming calcium fluoride and aluminate of sodium. 6NaF. AljFj + 6CaO = 6CaF, + sNajO. Al^Oj. The aluminate of sodium is then dissolved out with water, and carbon dioxide passed through the solution. 3Na,0. A]fi, -i- 3H,0 -|- 3CO, = sNa^CO, -|- Al,(OH)e. The AlzCOH)^ is precipitated and the sodium carbonate is crys- tallized out of the solution. At ordinary temperatures, sodium carbonate crystallizes in large rhombic crystals, containing 10 molecules of water, which eflloresce in dry air. It is soluble in water most freely at 38° C. (100.4° F-)- i'^ solutions have an alkaline reaction. When the crystals are calcined at a dull red heat, they disintegrate, give off' their water of crystallization, and form a white powder, the sodii carbonas exsiccata of theU. S. P. 100 parts of H2O, dissolve 10 parts of this anhydrous carbonate at 0° C. (32° F.), and 138 parts at 38° C. (100.4° F.). 317. Hydrogen Sodium Carbonate— Acid Sodium Carbonate — Sodium Bicarbonate — Sodii Bicarbonas (U. S. P.)— Sodae Bicarbonas (Br. P.), (NaHCO^)— is found in many mineral waters. It is produced by the ammonia process described above, and by the action of carbon dioxide upon sodium carbonate. Na^COs 4- COj -f HO2 = aNaHCOg. It forms small, rectangular prisms, which are anhydrous, but dis- solve in ten or eleven parts of water. Its solutions are nearly neutral to test paper. By heating the solid, or boiling its solu- tions, it gives off" carbon dioxide and is converted into the car- bonate. 230 MEDICAL CHEMISTRY. 318. Sodium Phosphates. — These are three in number. They are less soluble and crystallize more easily than the potas- sium salts of phosphoric acid. The tri-sodium phosphate, or basic phosphate (NajPOi), is made by saturating i molecule of phosphoric acid with 3 mole- cules of sodium hydroxide. It crystallizes in six-sidgd prisms, and is soluble in 5.1 parts of water at 15.5° C. CS9-9° F.). Its solution is alkaline to test paper. Hydrogen Disodium Phosphate — Disodium Phos- phate — Neutral Sodium Phosphate — Sodii Phosphas (U. S. P.)— Sodse Phosphas (Br. P.), (Na^HPOJ— is more stable than the other phosphates, and is the one generally em- ployed in medicine and in laboratories. It may be prepared by treating phosphoric acid with sodium hydroxide to feeble alkaline reaction. Below 30° C. (86° F.) it crystallizes in large, rhombic prisms, with 12 aq. ; at 33° C. (91.4° F.) it crystallizes with 7 aq. The salt with 12 aq. effloresces in air, losing 5 aq. ; that with 7 aq. does not. Both are freely soluble in water, and show a faintly alkaline reaction. Monosodium Phosphate — Acid Sodium Phosphate (NaHjPOj) — crystallizes in rhombic prisms with i molecule of water, and is acid in reaction. At 100° C. (212'' F.) it loses its water of crystallization, and at about 200° C. (392° F.) forms sodium pyrophosphate — sodii pyrophosphas (U. S. P.) (NaiPjO,. loHjO). It occurs as colorless, translucent prisms, permanent in the air, and having a slightly alkaline reaction. It is soluble in 12 parts of water, and insoluble in alcohol. When this salt is heated to 240° C. (464° F.) the metaphos- phate (NaPOa) is formed. NajHjPjO, = 2NaP03 + H.,0. 319. Sodium Nitrate — Chili Saltpetre — Sodii Nitras (U. S. P.), (NaNOs) — is found native in extensive deposits in Peru. It crystallizes in rhombohedra, which closely resemble cubes ; hence, it is called cubic saltpetre. It is deliquescent, and is, therefore, not adapted for the manufacture of gunpowder ; it has a cooling, saline, somewhat bitter taste. It is more readily soluble in water than potassium nitrate, which, in other respects, it quite closely resembles. It is used in the manufacture of nitric acid, and as a fertilizer. 320. Sodium Borates. — Six are known. The only one of importance is the Disodium Tetraborate — Sodium Pyro- borate— Borax— Tincal— Sodii Boras (U. S. P.), (Na^BiO, SODIUM. 231 .loHjO) — which is found -native in some of the lakes of Thibet, from which country it was formerly imported. The principal source now is the borax lake in California. It may be prepared artificially by boiling boric acid with sodium carbonate. Boric acid is found in the lagoons of Tuscany, and this is the present source. Borax crystallizes in large, hexag- onal prisms, with 10 molecules of HjO, or in regular octahedra with 5H2O. The former variety effloresces in dry air ; the latter is permanent. Both dissolve in 16 parts of cold, and 0.5 part of boiling water, forming a solution that has a feebly alkaline re- action. Upon heating, both salts puff up considerably, lose their water, and form a white, porous mass (burned borax), which finally fuses to a transparent glass. In the fused state, it will dissolve many metallic oxides, forming clear glasses, which often show a characteristic color on cooling ; thus, copper oxide gives a blue, and chromic oxide an emerald green glass. Borax is used in this way as a blowpipe test for certain metals. It is this property of dissolving oxides of the metals that ren- ders borax useful in welding and soldering metals. In these operations it is used to remove the oxide, or rust, from the sur- faces of the metals to be united. 321. Sodium Hypochlorite (NaCiO). — When in solution, Liq. Sodae Chlorat8e(U. S. P.), (Br.) — Labarraque's solu- tion. It may be prepared by decomposing a solution of chlorin- ated lime with sodium carbonate. CaClj -f Ca(C10)2 -|- 2Na5C03 = 2NaCl + 2NaC10 + 2CaC03. It should contain 2.6 per cent, by weight of available chlorine. It yields up its chlorine readily, thus acting as an efficient disin- fecting and deodorizing agent. 322. Sodium Chlorate — Sodii Chloras (U. S. P.), (NaClOa) — may be made by double decomposition between KCIO3 and sodium tartrate, NaHCiH^Oe, forming cream of tartar, KHC4H4O6, and NaClOj. 323. Sodii Benzoas (U. S. P.), (NaC,H502) — is made by adding benzoic acid to a solution of sodium bicarbonate, as long as effervescence continues. IiqHjOj + NaHCOj = NaCjHjOj + CO^ + H^O. It is a white powder, having a very faint, benzoin-like odor, and a sweet astringent taste. It is used as an antifermentative agent. Sodii Arsenas (U. S. P.), (Na^HAsO^ + yH^O,)— is made 232 MEDICAL CHEMISTRY. by heating to fusion arsenous acid,, with exsiccated sodium carbonate and sodium nitrate. Pyroarsenate of sodium is formed, which is converted into sodium arsenate when dissolved in water. Sodii Sulphocarbolas (U.S. P.), (NaSOsCeH^OH).— When crystallized carbolic acid is dissolved in strong sulphuric acid, sulphocarbolic acid is formed. When this is treated with barium carbonate, sulphocarbolate of barium is formed in solution. If this solution be now treated with sodium sulphate, a precipitate of barium sulphate will form and sulphocarbolate of sodium may be crystallized out from the solution. Sodii Acetas (U.S. P.) (NaQHsO^ + sH^O), may be made by neutralizing acetic acid with bicarbonate of sodium. NaHCOj + HCjHsOj = NaC^HjO^ + CO, + H^O. 324. Physiological Effects of the Sodium and Potas- sium Compounds. — The action of the halogen salts of these metals is generally that of the combined chlorine, bromine, or iodine. The hydroxides of both metals, and, to a lesser degree, the carbonates, tend to disintegrate the tissues with which they come in contact ; hence, they possess powerful caustic properties. If taken internally, the hydroxides are highly poisonous, causing death, like the mineral acids, either immediately by their cor- rosive properties, or secondarily, by exciting inflammation of the gastro-intestinal mucous membrane, with consequent thick- ening and constriction. In cases of poisoning by the caustic alkalies, the stomach should be evacu- ated, and a weak acid, such as dilute vinegar or lemon juice, given to neutralize the alkali ; or, it should be saponified by the administration of some oil or fat. The nitrate of these metals is toxic in its influence, and for it there is no direct antidote. The alkaline carbonates are, undoubtedly, of considerable import- ance to the carrying on of the normal functions of the animal body. In the first place, it is exceedingly probable that some, at least, of the albuminoid matters of the blood are held in solution by reason of its alkaline reaction, which is largely given to it by these carbonates. Secondly, it has been shown very clearly that the alkaline reaction of the blood is of first importance to the oxidation processes, which are intimately con- nected with the production of animal heat and retrograde metamorphosis. It is only in the presence of a free alkali that many organic substances will unite with oxygen, and thus their decomposition at the temperature of the body with- out an alkali would be impossible. In proof of this, it is known that, if the free vegetable acids are given, they will reappear in the urine, for the most part, unchanged ; but if they are in combination with the alkalies when given, they are thoroughly burned up in the blood, and reappear as carbonates. In fact, so important are these alkaline salts — carbonates and phosphates — that without them, albuminoid bodies will not support life. POTASSIUM. 233 The alkaline carbonates, when taken in sufficient quantity, ren- der the urine alkaline in reaction and increase the quantity. The tartrates, citrates and acetates of sodium and potassium have a very similar action upon the economy to that of the carbonates, into which they are converted either in the intestines or blood. A slightly more cathartic action is attributed to the tartrates than is possessed by the carbonates. This action is also more or less shown by the sulphates and phosphates. POTASSIUM (Kalium). 325. Occurrence. — This metal is found widely distributed in rocks and minerals, principally as silicates. By the action of the atmosphere and other influences, these silicates gradually decom- pose, the potassium passes into the soil and is absorbed by the plants, from the ashes of which it may be obtained. The chlo- ride and sulphate are also found in sea-water, and in large de- posits, mixed with other chlorides. A chloride of potassium is mined in Stassfurth, Germany, as a source of potassium salts. Preparation and Properties. — It is prepared by calcining an intimate mixture of the carbonate with carbon. K,C03 + C, = K, + 3CO Such a mixture may be made by heating organic potassium salts, as crude tartar, to redness. In this way a black mass is formed, consisting of potassium carbonate and free carbon. By heating this black mass to a white heat in an iron retort, the potassium distils off, and is condensed under mineral naphtha. Potassium is a silver-white, lustrous metal, brittle at 0° C. (32° F.), waxy at 15° C. (59° F.), fuses at 62° C. (143.6° F.), and distils at a red heat. Sp. gr. at 15° C. (59° F.) = 0.865. I's affinity for oxygen is such that, if it be exposed to the air, it tar- nishes at once. It decomposes water or ice with great energy, with the formation of potassium hydroxide and the liberation of hydrogen, which is ignited by the high temperature caused by the reaction. It combines directly and energetically with the halogens, sulphur, phosphorus, arsenic, antimony, and tin. The haloid salts of potassium may be formed by direct union of the haloids with the metal, or by saturating the hydroxide or carbonate with one of the haloid acids. They all have a bitter, salty taste, are freely soluble in water, and crystallize in cubes. They fuse easily, and are somewhat volatile. 234 MEDICAL CHEMISTRY. 326. Potassium Chloride (KCl) occurs native, either pure or mixed with other chlorides. At Stassfurth it is found in large deposits, as sylvite and carnallite (KCl.MgCl2.6H2O). These deposits form the chief source of the potassium compounds. The chloride crystallizes in anhydrous cubes, of sp. gr. 1.84, closely resembling common salt. 100 parts of water dissolve 30 parts at 0° C. (32° F.), and 0.2738 part more for every degree of increase of temperature. 327. Potassium Bromide — Potassii Bromidum (U. S. P., Br.), (KBr) — is generally obtained by dissolving bromine in a solution of potassium hydroxide ; the bromatealso produced in the reaction is converted into bromide by calcining the product with charcoal. SBfj + 6K0H = sKBr + KBrO., + jH^O SKBr + KBrOj + 0^ = 6KBr + 3CO. It may also be prepared by acting upon ferrous bromide with potassium carbonate. FeBr^ + K^COj = FeCOj + 2KBr. It has the general properties of the other haloid salts, and is used in photography and in medicine. 328. Potassium Iodide— Potassii lodidum (U. S. P., Br.), (KI) — may be prepared like the preceding, by using iodine instead of bromine, or by using ferrous iodide instead of bromide. It crystallizes in large, white, translucent cubes, salty in taste and permanent in air. It dissolves to the extent of 100 parts in 73.5 parts of water at ordinary temperatures. Its aqueous solution dissolves iodine in large quantities, forming the compound solution of iodine (U. S. P.). It also dissolves many metallic iodides to form double iodides. Its medicinal effects are those of iodine. When employed in chronic poisoning by lead or mercury, it is supposed to unite with the metals in the blood or tissues, to form soluble iodides, and thus pass them out by the urine. There is an ointment of KI official, containing 12 per cent, of KI. Potassium Fluoride (KFl). — Its aqueous solution attacks glass. Is not of much importance to the medical student. 329. Potassium Cyanide — Potassii Cyanidum (U. S. P.), (KCN) — may be obtained either by saturating potassium hydroxide with hydrocyanic acid, or by heating potassium ferro- cyanide. It is a white, amorphous, deliquescent mass, easily fusible, and smelling of cyanogen. Its solution is very poisonous. POTASSIUM. 23s Its effects upon the economy are uncertain, but are probably those of hydrocyanic acid. In case of poisoning by it, the stomach should be evacuated and the antidotes of hydrocyanic acid given. Ferrocyanide and Ferricyanide — see page 213, Art. 276. 330. Potassium with Oxygen — Potassium Oxide (K^O) — results from the direct oxidation of potassium, by simply exposing thin strips of the metal to dry air, or by the action of potassium upon the hydroxide. 2KOH + Kj = 2K2O + H^. It is a white, deliquescent, caustic powder, uniting readily with water to form the hydroxide. 331. Potassium Hydroxide — Potassium Hydrate — Caustic Potash — Potassa (U. S. P.), Potassa Caustica (Br.), (KOH) — is prepared by the reaction of potassium car- bonate upon calcium hydroxide (slaked lime). K2CO3 + Ca(0H)2 = CaCOs + 2KOH. After these substances have been boiled together, the solution is allowed to settle. The clear liquid is then poured off, evaporated, and the residue fused in a silver dish. The fused mass is then cast into sticks. This is called potash by lime, and is not pure. To render it purer, it is dissolved in alcohol, the solution evapor- ated to dryness, the residue again melted and cast in silver moulds. This product is potash by alcohol, and is free from the chloride and other potassium salts. It is a white, opaque, brittle solid, usually met with in the form of cylindrical sticks, but sometimes in lump. It has a specific gravity of 2.1. It fuses quite easily, and, at high temperatures, volatilizes undecomposed. It is freely soluble in water ; less so in alcohol. The solutions have a marked alkaline reaction, saponify fats, and are strongly caustic. Exposed to the air, it absorbs water and carbon dioxide, and is changed into the carbonate. In watery solution it is largely used as a reagent in chemical analysis ; it dissolves chlorine, bromine, iodine, sulphur, and phosphorus. It decomposes the ammoniacal salts, liberating ammonia ; it also decomposes the salts of many of the metals, with the formation of a potassium salt and a hy- droxide or oxide of the metal. Potassa cum Calce (U. S. P.) is made by rubbing together, in an iron mortar, lime and potassa so as to form a powder. It is to be kept in a well-stoppered bottle. Liquor Potassae is a 5 per cent, aqueous solution of potas- sium hydroxide. 236 MEDICAL CHEMISTRY. 332. Potassium Chlorate — Potassii Chloras (U. S. P.), (KCIO3). — When a hot, concentrated solution of potassium hydroxide is treated with chlorine gas, the following reaction occurs: — 6K0H + 3Clj = sKCl + KCIO3 + aHjO. It is usually made by the action of chlorine upon a mixture of calcium hydroxide and potassium chloride. By this method a double reaction takes place. Calcium chlorate is first formed. 6Ca(OH)2 + 6CI2 = sCaClj + Ca(C103)2 + eH^O. This then reacts with the potassium chloride as follows : — Ca(C103)j + 2KCI = 2KCIO5 + CaClj. The hot solution is rapidly evaporated, and the residue purified by recrystallization. It crystallizes in shining, transparent plates of the monoclinic system. Soluble in 16. 7 parts of water at 15° C. (59°F.); soluble with difficulty in alcohol. It is cooling and astringent to the taste, fuses at 234° C. (453° F.), and above 532° C. (665.6° F.) it is decomposed, giving up a portion of its oxygen and changing to the perchlorate (KCIO4), which at higher temperatures decomposes into oxygen and potassium ' chloride. As it gives up oxygen easily, it serves as a valuable oxidizing agent and as a means of preparing this gas. Mixed with readily oxidizable substances, as carbon, sulphur, phos- phorus, sugar, tannin, resins, etc., the mixtures explode when heated or subjected to a sudden shock. The igniting material with which parlor matches are tipped consists of antimony sul- phide and potassium chlorate. When rubbed upon a surface coated with red phosphorus they ignite. 333. Potassium Hypochlorite (KCIO) is formed by the action of chlorine upon a cold solution of potassium hydroxide. 2KHO + CI2 = KCl + KCIO + HjO. It can only be obtained in aqueous solutions. If the solution be evaporated, the salt splits up into chloride and chlorate. 3KCIO = 2KCI + KCIO3. When treated with acids, it yields free chlorine and bleaches strongly. The ordinary solutions used in bleaching are solutions of impure sodium and potassium hypochlorite. 334. Potassium Nitrate — Nitre — Saltpetre — Potassii Nitras (U.S. P.), (KNO3) — exists native, and is produced arti- POTASSIUM. 237 ficially whenever nitrogenous organic substances decay in the presence of potassium carbonate. Upon the so-called saltpetre plantations, manures and various animal refuse are arranged in layers with wood ashes and lime, in large heaps, and submitted to the action of the air for two or three years, whereby, from the slow oxidation of the nitrogen, nitrates of potassium and calcium are produced. The contents of the heaps are then lixiviated with water, which dissolves the potassium and calcium nitrates. Potassium carbonate is added to the solution to convert the last salt into potassium nitrate. Ca(N03)j + KjCOa = CaCOj + 2KNO3. The calcium carbonate is filtered off, and the solution evaporated. Another method, and probably the one most frequently employed at present, consists in the decomposition of sodium nitrate (Chili saltpetre) by means of potassium carbonate, or chloride. NaNOa + KCl = NaCl + KNO3. It crystallizes in large, six-sided, rhombic prisms. 100 parts of water dissolve 244 parts of the salt at 100° C. (212° F.), but at 0° C. (32° F.) only 13 parts. It fuses at 353° C. (667° F.). Below a red heat it decomposes into oxygen and potassium nitrite, KNOj. The readiness with which it gives up its oxygen, when heated in the presence of an oxidizable substance, renders it of value as an oxidizing agent. Gunpowder is a granular mixture of potassium nitrate, sulphur, and charcoal, in such proportion that the nitrate contains all the oxygen necessary for the combustion of the sulphur and charcoal. The following equation expresses ap- proximately the decomposition caused by the burning of powder : — 2KNO3 -f S -f 3C = K,S + 3CO, + N,. The effect produced, therefore, depends upon the disengagement of carbon dioxide and nitrogen, the volume of which gases is almost 100 times greater than that of the powder. The heat of the combustion further expands the gases at the time of the explosion. 335. Potassium Carbonate— Potassii Carbonas (U. S. P.)— Potassae Carbonas (Br.)— Salt of Tartar— Pearlash — (K2CO3) — exists in mineral waters, in the animal economy, and as the principal ingredient of wood ashes. Plants absorb potas- sium salts from the earth and convert them into salts of the organic acids. When the plants are burned, the organic acids are destroyed and potassium carbonate produced, which is ob- 238 MEDICAL CHEMISTRY. tained by lixiviation of the ashes and evaporation. This method is not much employed at present. The immense deposits in Stassfurth and Galicia afford an almost inexhaustible supply of potassium salts. It occurs commercially as a white, granular, deliquescent powder, freely soluble in water, the solution having a caustic taste and an alkaline reaction. Potassium carbonate is largely made, by the Leblanc process^ from the native chloride. A very pure potassium carbonate is made from argols (impure bitartrate of potassium) by calcina- tion. 2KHC,HA + SO, = K,C03 + 7CO, + SH,0. 336. Potassium Bicarbonate — Hydropotassium Car- bonate — Potassii Bicarbonas (U. S. P.) — Potassse Bicar- bonas (Br.), (KHCO3). — When carbon dioxide is passed thropgh a concentrated solution of potassium carbonate, it is absorbed and potassium bicarbonate is produced. KjCOg + HjO + CO2 = 2KHCO3. This salt crystallizes in oblique, rhombic prisms, of the mono- clinic system. It dissolves in 3 to 4 parts of water; the solution is faintly alkaline but not caustic. The substance that is still extensively used in some parts of the country in baking, under the name of saleratus, is this, or the corresponding sodium salt. It "raises" the bread by the action of heat in setting free the carbon dioxide, and leaving potassium (or sodium) carbonate, which, by its strongly alkaline reaction, may cause digestive dis- turbances. 337. Sulphides. — Five are known : K^S, K2S2, K2S3, K2S4, and K2S5 ; also a sulphydrate, KSH. The latter is prepared by the action of hydrogen sulphide upon potassium hydroxide. KOH -I- HjS = KSH + HjO. The Pentasulphide — Liver of Sulphur — ^^Potassa Sul- phurata (U. S. P.)— Potassa Sulphureta (Br.), (K2S5)— is obtained by fusing potassium carbonate with an excess of sulphur. It decomposes readily, and treated with hydrochloric acid it gives off hydrogen sulphide. 338. Potassium Sulphate — Dipotassium Sulphate — Potassii Sulphas (U. S, P.)— Potassse Sulphas (Br.), (KjSOi) — is found in the Stassfurth mines, in plant ashes, and in solution in mineral waters. It is obtained by the action of sul- phuric acid upon potassium chloride, as a by-product in some chemical manufacturing processes. POTASSIUM. 239 2KCI + H^SOi = KjSOj + 2HCI. It crystallizes without water, in small, rhombic prisms, of a bitter, salty taste, and is soluble in 10 parts of water at ordinary tem- peratures. 339. Hydropotassium Sulphate — Monopotassium Sulphate — Acid Potassium Sulphate (KHSO,) — is formed as a by-product in the manufacture of nitric acid from potassium nitrate; crystallizes in large, rhombic tables, and is very readily soluble in water. At about 200° C. (392° F.) it fuses, loses water, and is converted into the pyrosulphate (KjSjO,). 340. Sulphites. — Three are known : K^SOg, KHSO3, and KjSjOj. Po- tassium Sulphite — Neutral Potassium Sulphite — Potassium Sulphis (KjSOj). — This salt crystallizes in oblique rhombic oclahedra, which dissolve readily in water, and have a sulphurous odor. When in solution, if exposed to the air, it absorbs oxygen, and is converted into the sulphate. 341. Potassium Acetate — Potassii Acetas (U. S. P.) — Potassae Acetas (Br.), (KCjHjO,)— exists in the juices of plants. It is obtained by neutralizing acetic acid with potassium carbonate or bicarbonate. It crystallizes in shining needles, is deliquescent, and very soluble in water. 342. Oxalates. — Three are known to exist : Potassium Oxalate — Neu- tral Oxalate (KjCjO^ -(- Aq.), formed by saturating oxalic acid with potassium carbonate. Hydropotassium Oxalate— Monopotassium Oxalate — Binoxalate of Potash (2KHC204). Potassium Quadroxalate (KHCjO^.- CjO^Hj -|- I Aq.). A mixture of these two salts is known as salt of lemon, or salt of sorrel, and is used for bleaching straw and to remove ink stains. In appearance it closely resembles Epsom salt, and has caused many cases of oxalic acid poisoning, being taken by mistake for that salt. 343. Tartrates.— Potassium Tartrate — Soluble Tartar — Neutral Tartrate of Potash— Potassae Tartras (Br.), (KjQHjOg)— is awhite, crys- talline powder, very soluble in water ; soluble in 240 parts of alcohol. Hy- dropotassium Tartrate — Cream of Tartar — Potassii Bitartras (U.S. P.), Potassae Bitartras (Br.), (KHC^H^Oj). A brown-red, crystalline crust is obtained from the bottom and sides of wine casks after fermentation has taken place ; this is known in commerce as argol, or crude tartar, and is composed in great part of potassium bitartrate, with tartrate of lime and coloring matter. The argol is boiled with water, or heated in a closed digester by superheated steam. The latter process renders the calcium tartrate insoluble and separates it almost completely from the cream of tartar, which goes into solution. The solution thus obtained is allowed to cool and crystallize ; the crystals are re- dissolved in hot water, treated wuh animal charcoal, to remove coloring mat- ters, filtered, and again crystallized. The product of this process is almost chemically pure acid potassium tartrate. It crystallizes in hard, opaque, rhombic prisms, very sparingly soluble in water, still less so in alcohol. Its solution is acid to the taste, and to litmus paper. It is largely used in baking, combined with sodium bicarbonate, the two substances reacting upon each other to form Rochelle salt, with liberation of carbon dioxide. Baking powders are extensively used at present, instead of yeast, for raising cake, biscuits, etc. In all of them the action depends upon 240 MEDICAL CHEMISTRY. the decomposition of sodium bicarbonate by some salt havingan acid reaction or by a weak acid. In addition to the bicarbonate, and the starch added to preserve them, many of them contain either tartaric acid, alum, or acid phosphate of calcium, in- stead of cream of tartar. Some of the reactions that take place to set free the carbon dioxide are the following : — I. KHCjH^Og + NaHCOj = NaKC^HjOj + H^O + CO^. Potassium Sodium Sodio-potassmui Water. Carbon Bitartrate Bicarbonate. Tartrate. Dioxide. 2. Al2(SO^)3.K2S04 + 6NaHC03 = KjS04 + sNajSO^ + Aluminium potassium Sodium Potassium Sodium Alum. Bicarbonate. Sulphate. Sulphate. Al^HeOe + 6CO,. Aluminium Carbon Hydroxide. Dioxide. 3. CaH,(P04)2 + zNaHCOs = CaHPOj +NaHPO + Calcium Sodium Hydro-calcium Sodium Biphosphate. Bicarbonate. Phosphate. Phosphate. 2H2O + 2COj. Water. Carbon Dioxide. A good powder may be made by intimately mixing two parts cream of tartar with one of sodium bicarbonate, and adding a little flour or starch. Sodium Potassium Tartrate— Rochelle Salt — Potassii et Sodii Tar- tras (U. S. P.), (NaKCjHjOg -|- 4Aq.), — is prepared by boiling acid potassium tartrate with sodium carbonate. 2KHC4H4O5 -f NajCOj = 2KNiLCJif)s + CO^ -f H^O. It forms large, transparent, prismatic, slightly efflorescent crystals, soluble in 1 .4 parts of cold water, saline, and slightly bitter to the taste, and neutral in reaction. Potassium Antimonyl Tartrate — Tartrated Antimony — Tartar Emetic— Antimonii et Potassii Tartras (U. S.), (SbOKC^HjOj), — is pre- pared by boiling a solution of cream of tartar with antimonious oxide. Its crystals are transparent, right rhombic octahedra, efflorescing in the air. It is quite soluble in water, the solution having a nauseating, metallic taste. It is poisonous, and has even caused death when applied to the skin as a local irri- tant and vesicant. RUBIDIUM and C/ESIUM. Kb =85.3 Cs— 132.6. 344. These rare metals were discovered in i860 by Bunsen and Kirchoff, by means of the spectroscope. Both elements were named from the color of their lines in the spectrum (rubidius, dark red, and caesius, sky blue). They occur in small quanti- ties, widely distributed, often accompanying potassium. With platinum chloride they form double chlorides (PtCl4.2RbCl). Rubidium iodide has been used in medicine. AMMONIUM COMPOUNDS. 24I AMMONIUM COMPOUNDS. 345. Ammonium (NHj). — This radical has only a hypo- thetical existence, never having been isolated. But there are many reasons for believing that it does actually exist in combina- tion in the ammonium compounds, and that in these compounds it plays the role of a metal resembling sodium and potassium. The oxide of this radical has not been separated. 346. Ammonium Chloride — Ammonium Muriate — Sal -Ammoniac — Ammonii Chloridum (U. S. P., Br.), (^NH^Cl) — was formerly obtained by the dry distillation of camel's dung. At present it is prepared chiefly by saturating the ammonia water from gas works with hydrochloric acid, evaporat- ing the solution to dryness, and subliming the residue in iron vessels. Prepared in this way, it is a compact, tough, fibrous mass, which dissolves in 2.7 parts cold and one part boiling water. It crystallizes from its solution in small octahedra or cubes, of a sharp, salty taste, and neutral reaction. When heated, it volatilizes without fusing; at the same time a dissociation into NH3 and HCl occurs, but on cooling these products recombine into ammonium chloride. This salt exists in minute quantities in the gastric juice of various animals. The urine, saliva, and tears also contain some ammonium compound, which is said to be the chloride. 347. Ammonium Bromide — Ammonii Bromidum (TJ. S. P., Br.), (NH4)Br.) — may be prepared by direct combi- nation of ammonia and hydrobromic acid, or by decomposing ferrous bromide with aqua ammonise, FeBr^ + aNH^OH = Fe(0H)2 + aNH^Br, or by subliming a mixture of potassium bromide and ammonium sulphate. 2KBr -I- (NHJjSOi = aNH^Br + K^SO^. It forms a white, granular powder, or large prisms, which turn yellow on exposure to air, and possess a saline, pungent taste and neutral reaction. It dissolves in 1.5 parts of water, and volatilizes without decomposition. 348. Ammonium Iodide — Ammonii lodidum (U. S. P.), (NH4)I) — is prepared by the action of hydriodic acid upon ammonia, or by the double decomposition of potassium iodide and ammonium sulphate. 242 MEDICAL CHEMISTRY. 2KI + (NHi),SO^ = zNHJ + KjSOi. It may also be prepared by adding ammonia water to a solution of ferrous iodide. Felj + zNHjOH = Fe(OH)2 + 2NHJ. It forms cubic crystals, which are deliquescent and are soluble in 0.60 part of water. They decompose in air, turning yellow and emitting the odor of iodine. 349. Ammonium Hydroxide CNH4OH) is believed to exist in solution in the ordinary aqua ammoniae, although, when the attempt is made to isolate it, decomposition ensues. (See Art. 193.) It is made by acting upon ammonium chloride or sulphate with calcium hydroxide. 2NHJSO4 + Ca(0H)2 = CaSOj + 2NH4OH. Aqua Ammoniae Fortior (U. S. P.) has a sp. gr. of o.goi, and contains 28 percent. NHj. Aqua Ammoniae (U. S. P.) is of sp. gr. 0.960, and contains 10 per cent. NH3. 350. Ammonium Carbonates. — Three are known : Am- monium Carbonate — Neutral Ammonium Carbonate (NH4)2CO,,) — may be prepared as a crystalline powder by passing ammonia gas through a concentrated solution of the sesquicar- bonate. Exposed to the air, it splits up into ammonia and the acid carbonate, NH4HCO3. (NHJ2CO3 = NH4HCO3 + NH3. Hydro-ammonium Carbonate — Acid Ammonium Car- bonate (NH4HCO3) — is obtained when a solution of ammonium hydroxide or sesquicarbonate is saturated with carbon dioxide. It forms large, rhombic crystals, which are quite soluble in water. At 60° C. (140° F.) it is decomposed into ammonia and carbon dioxide. Ammonium Sesquicarbonate — Sal- Volatile — Ammo- nii Carbonas (U.- S. P.) (HN4HCO3 + NH^NH^CO^)— is the commercial carbonate of ammonia, and was formerly prepared by the dry distillation of bones, horns, and other animal sub- stances. It is at present prepared by heating a mixture of ammo- nium chloride or sulphate with calcium carbonate, and condensing the volatilized product. As seen by the formula, it is a mixture of the acid carbonate and the carbamate, though probably when fresh it consisted of the pure neutral carbonate. So prepared. AMMONIUM COMPOUNDS. 243 it sublimes as a white, transparent, hard mass, "having an ammo- niacal odor and an alkaline reaction. On exposure to the air, it gives off ammonia and carbon dioxide. The carbonate's of ammonia are very unstable. 351. Ammonium Nitrate — Ammonii Nitras (U. S. P.) (NH^NOa) — is prepared by neutralizing nitric acid with ammo- nium hydroxide or carbonate. It crystallizes in flexible, six- sided prisms, without water; dissolves in 0.5 part water at 15° C. (59° F.), and fuses at 165° C. (330° F.). When heated to 210° C. (410° F.), it decomposes, with the formation of nitrous oxide, or laughing gas, and water. (NHJNO3 = N2O + 2H2O. 352. Ammonium Sulphate — Neutral Ammonium Sul- phate — Ammonii Sulphas (N4H)2S04) — may be obtained by saturating the ammonium water from gas works with sulphuric acid. It forms rhombic crystals, soluble in two parts of cold and one part of hot water. At 140° C. (284° F.) it fuses, and at higher temperatures it decomposes into ammonia, nitrogen, water, and ammonium sulphite. 353. Ammonium Acetate (NH4)C2H30.i) is formed when acetic acid is saturated with ammonia water or ammonium car- bonate. It is seldom seen except in solution in water. The aqueous solution is used in medicine as the Liq. Ammonii Acetatis, or Spirit of Mindererus, which contains about 7 per cent, of the salt. Other salts in use are the benzoate, phosphate, and valerianate, all white crystalline salts. The benzoate, NH4- QHsOj, and the Valerianate, NH4C5H9O2, are official. 354. Ammonium Sulphide .(NH4)2S) is a white, crystal- line solid, formed by mixing dry hydric sulphide and ammonia at a low temperature — 18'^ C. (about 0° F.). It is usually prepared by mixing the sulphydrate with sulphur. It dissolves sulphur and the sulphides of arsenic, tin, and antimony, and is used in analysis for this purpose. Ammonium Sulphydrate (NH^SH) is prepared by saturat- ing a solution of ammonium hydroxide with hydrogen sulphide (sulphuretted hydrogen). It is colorless at first, but becomes yellow, on exposure, from decomposition. It is used in labora- tories as a reagent. Acids decompose both these sulphides, set- ting free sulphur. 355. Action on the Economy. — In large quantities, or by 2 44 MEDICAL CHEMISTRY. prolonged use, ammonia and its salts are poisonous. Ammonia, if inhaled, acts as a severe irritant upon the air passages, causing dyspncea, pain, suffocation, and even death. The treatment in cases of poisoning consists in neutralizing the alkali by dilute acids ; or, the vapor of acetic or dilote hydrochloric acid may be inhaled. Two drachms of a strong solution of ammonium hydroxide have proved fatal. COPPER (Cuprum). Cu = 63. s. 356. Occurrence. — This metal occurs in the free state in large masses, or crystallized in cubes and octahedra. It is found in the vicinity of Lake Superior, in China, Japan, Sweden, and in the Urals. Its most important ores are : cuprite (CujO), malachite, and azurite (basic carbonates), chalcocite (CujS), and chalcopyrite, or copper pyrites (CuFeS^). 357. Preparation. — The mixed copper ores are first roasted in the air, by which process a portion of the copper sulphide is converted into oxide ; this is then roasted with a silica flux and carbon. By this process the iron sulphide is converted into a silicate, and is drawn off with the slag. After several repetitions of this process the so-called copperstone is obtained; this contains both the sulphide and oxide. By repeated roasting and heating, the copper oxide reacts upon the sulphide, and metallic copper results. Some poor ores are first treated with sulphuric acid, and the resulting sulphate is then treated with scrap iron, which precipitates the copper in the- metallic state. Chemically pure copper is obtained by electrolysis, or by heating the pure oxide in a stream of hydrogeii. 358. Properties. — Copper is a red metal by reflected light, while thin leaflets transmit a green light. It is soft, ductile, and tenacious ; a good conductor of heat and electricity; specific gravity 8.914 to 8.952. In dry air it undergoes no change, but in moist air it gradually becomes coated with a thin layer of green basic carbonate. When heated, it oxidizes to black cupric oxide (CuO). Hot sul- phuric, nitric, and hydrochloric acids dissolve it, with libera- tion of sulphur dioxide, nitrogen dioxide, and hydrogen, re- spectively. With organic acids it forms soluble salts in the presence of air and moisture j hence, acid fruits should not be kept in copper vessels. COPPER. 245 359. Cuprous Compounds. — These are very unstable, absorb ox)gen, and are converted into cupric compounds. If the formulae CuCI, Cul, Cu^O, and CU2S are correct, copper in the cuprous compounds would appear, like silver, to be univalent. It has never been de- termined, however, whether these formulae really express the true molecules. Copper compounds are not volatile, and we have no means of ascertaining the size of the molecule. As has already been stated, most chemists believe that in the cuprous compounds copper is bivalent, and that they contain the group Cug'''', whose valence is always two. 360. Cuprous Chloride — Subchloride, or Protochlo- ride (CuCl or CujClj) — is produced, together with cupric cblo-. ride, by igniting metallic copper in chlorine gas ; by dissolving cuprous oxide in hydrochloric acid without contact of air ; or by the action of many reducing agents upon solutions of cupric chloride. It is a heavy white powder, rapidly becoming green in the air, owing to the absorption of oxygen and formation of cupric chloride (Cu.;^ PI j. It dissolves in concentrated hydro- chloric acid, but not in water. With carbon monoxide it forms a crystallizable compound. Its hydrochloric acid solution is used in gas analysis to absorb this gas. 361. Cuprous Iodide (Cujlj) is precipitated, together with iodine, from soluble cupric salts by potassium iodide. 2CUSO4 + 4KI = 2K2SO4 + Cujj + \. On dissolving out the iodine with ether, the iodide is left as a gray insoluble powder. 362. Cuprous Sulphide — Subsulphide, or Protosul- phide (Cu^S) — occurs in the mineral chalcocite, as soft, fusible, gray crystals ; also in many double sulphides, among which the most important is the double sulphide of copper and iron, or copper pyrites. 363. Cuprous Oxide — Suboxide (CujO) — occurs in nature as cuprite. It is obtained artificially by boiling an alkaline solution of grape sugar and copper sulphate. It precipitates as a bright red powder. (Fehling's and Trommer's tests.) The hydroxide (Cu2(OH)2) is precipitated by the alkalies, from hydrochloric acid solutions of CujCIj, as a yellow powder. 364. Cupric Compounds. — Cupric Chloride (CuClj) is formed by dissolving cupric oxide or carbonate in hydrochloric acid. From aqueous solutions it crystallizes in bright green, rhombic needles with 12H2O. It is readily soluble in water and 246 MEDICAL CHEMISTRY. alcohol. When heated, it parts with its water, and forms anhy- drous cupric chloride, which at a red heat gives off chlorine. 2CuCI, + heat = Cu^CIj -f- Clj. Cupric Bromide resembles the chloride. The iodide is not known. 365. Cupric Oxide— Binoxide — Black Oxide (CuO)^is prepared by heating copper turnings to redness in the air, or by calcining the nitrate. It forms a black amorphous powder, readily reduced to the metallic state by heated charcoal, hydro- gen, or the alkaline metals. If heated in the presence of organic substances, it oxidizes them completely, and is thereby reduced to metal. It is used in organic analysis for this purpose. 366. Cupric Hydroxide (Cu(0H)2) is formed as a volumi- nous, bluish-white precipitate when sodium or potassium hy- droxide is added to a solution of a copper salt. When heated, even under water, it becomes dehydrated and changed to black cupric oxide. Copper oxide and hydroxide dissolve in ammonium hydroxide, forming a dark-blue solution. This solution is often used as a solvent for cellulose, from which solution acids precipitate it again. 367. Cupric Sulphate — Blue Vitriol — Blue Stone — Cupri Sulphas (U. S. P., Br.), (CuSOi-sH^O). This is the only official salt of copper. It may be prepared, first, by roasting chalcocite ; second, from the water of certain copper mines ; third, by exposing copper moistened with dilute sulphuric acid to the air ; fourth, by dissolving copper oxide in hot, concen- trated sulphuric acid. CuO + HjSOj = CuSOj -I- HjO It forms large, blue triclinic crystals, which dissolve in 2.6 parts of water at 15° C. (59° F.), and in 0.55 part of water at 100° C. (212° F.). It loses four molecules of water at 100° C. (212° F.), while the fifth separates above 200° C. (392° F.), leaving a white amorphous powder, which readily takes up water, and in so doing resumes its blue color. Solutions of copper salts have a blue color, acid reaction, and metallic, styptic taste. Ammonium hydroxide added to a solution of copper sulphate precipitates a bluish-white cupric hydroxide, which dissolves in an excess of the alkali, forming a deep blue solution consisting of ammonio-sulphate of copper, cupric-tetrammonium sulphate, Cu(NH3)4S04. This solution is used as a test for COPPER. 247 arsenic. Alcohol floated on this solution causes to separate long, right rhombic prisms of cupric-tetrammonium sulphate, which are very soluble in water. Cupric sulphate also enters into the alkaline cupric tar- trate solution — Fehling's Solution. 368. Cupric Carbonates. — The neutral carbonate (CuCOa) is not known. When alkaline carbonates are added to solutions of copper salts, the basic carbonate separates as a green precipi- tate, having the formula CuC03.2Cu(OH2). This occurs in nature, especially in Siberia, as malachite. Another basic salt, tricupric carbonate, or sesquicarbonate of copper, is the beautiful blue azurite. 369. Copper Arsenite — -Scheele's Green is prepared by adding a solution of sodium or potassium arsenite to a solution of a copper salt. It is a green powder, composed of copper arsenite and copper hydroxide. It is insoluble in water, but soluble in ammonium hydroxide or the mineral acids. It is exceedingly poisonous, but is often used as a pigment to color wall papers, toys, and even confectionery. Schweinfurt Green — Mitis Green, or Paris Green (Cu(C2H302)2 4" sCCuOjAsj), is the commonest and most danger- ous of the cupro-arsenical pigments. It is prepared by adding a concentrated solution of cupric acetate to a boiling solution of arsenious acid. It is an insoluble, green, crystalline powder, decomposed by prolonged boiling in water, by aqueous solutions of the alkalies, and by the mineral acids. It is also soluble in ammonium hydroxide. 370. Cupric Acetate (Cu(C2H302)2) is formed by the de- composition of a solution of copper sulphate by lead acetate. It separates in large, bluish-green, prismatic crystals, with one molecule of.HjO, which it loses at 140° C. (284° F.). The dry salt, when heated to 250° C. (482° F.), decomposes with libera- tion of glacial acetic acid. Basic Acetates. — Verdigris — Cupric Subacetate is a complex mixture of copper acetate and hydroxide. It is prepared by exposing to the air piles composed of alternate layers of grape skins and copper plates, and after some time removing the bluish-green coating from the copper plates.* * The term verdigris is now often popularly applied to the green carbonates, hydroxides, or salts of organic acids, which accumulate on the surface of copper. 248 MEDICAL CHEMISTRY. 371. Copper Pigments. — The most important are : Brigh- ton Green, a mixture of copper acetate and chalk. Bruns- wick Green, originally an impure chloride, but now generally a mixture of carbonate and chalk. Mountain Green, or Mineral Green, is a native green carbonate of copper, some- times containing orpiment. Neuwieder Green, another name for mineral green or Schweinfurt green, mixed with gypsum or barium sulphate. Green Verditer is a mixture of the basic carbonate, oxide, and chalk. 372. Physiological Action of Copper. — Until recently, toxicologists were universally of the opinion that all the copper salts are poisonous. Of late, however, this has been considerably modified. Most of the copper compounds have an irritant, local action if brought into contact with the gastric or intestinal mucous membrane, causing vomiting of greenish-matter, cramps, etc. On the other hand, there are numerous instances in which severe ill- ness, characterized by nervous and other constitutional symptoms, has followed the use of food that has been in contact with imper- fectly tinned copper vessels. Some such cases have proven fatal. It has been conclusively shown, however, that pure and non- irritating copper compounds may be taken in considerable quan- tity without any bad results. Copper sulphate is frequently used as an astringent in medi- cine, and has been recommended in cholera and dysenteric troubles. This salt may be taken in considerable doses, with only an emetic effect. Cases of acute poisoning are not common, but many are recorded. Chronic poisoning is occa- sionally seen in those who work in copper, characterized by colicky pains, emaciation, impaired digestion, diarrhoea, and often a catarrhal cough. In most cases there is a green line on the margin of the gums. Copper is very likely to become con- taminated with arsenic ; and it is possible that some of the cases of reported copper poisoning ought to be attributed to arsenic. The organic salts of copper seem to be more poisonous than the inorganic. Canned peas, pickles, and other fruits are often contaminated with copper, and the manufacturers have fre- quently been punished by fines; but there exists a difference of opinion as to the dangers of copper in such goods. As long, however, as there is a chance for doubt, sanitary authorities should prohibit it use. The chemist must remember that most articles of food contain traces of copper. The treatment of cases of irritant copper poisoning should consist in the exhibition of milk, white of egg, and other SILVER. 249 albuminous substances, with which the copper salt may form an inert compound. Emesis should be induced if it has not taken place spontaneously. SILVER (Argentum). Ag — 108. 373. Occurrence. — This metal occurs in nature in combi- nation with chlorine, bromine, iodine, sulphur, arsenic, copper, antimony, etc. The principal localities in which it is found are the western United States, Mexico, Hungary, and Saxony. It is found native to some extent. The lead ore, galena, furnishes much silver. 374. Preparation. — For an elaborate description of the pro- cess by which silver is extracted from its ores, the student is referred to works on metallurgy. As usually obtained by these processes the metal is not pure, but is contaminated to a greater or less extent by copper and other metals. To obtain it chemi- cally pure, the ordinarily occurring silver is dissolved in nitric acid, and from this solution of the nitrates silver is precipitated as chloride by hydrochloric acid or common salt. The silver chloride thus obtained may be reduced by fusion with sodium carbonate, or by the action of zinc or iron in the presence of water. 2AgCl + Zn = ZnClj + 2Ag. 375. Properties. — A brilliant white metal; sp. gr. 10.47 'o 10 54. It is tolerably malleable, soft, very ductile, and is the best known conductor of heat and electricity. It does not oxidize in the air, but frequently tarnishes in ordinary atmo- spheres from the presence of minute quantities of hydrogen sulphide, which blacken it. With the members of the halogen group it unites directly. It dissolves in hot, strong sulphuric acid, to form the sulphate, Ag, + HjSOi = Ag,SO, + H„ but is more easily attacked by nitric acid, which dissolves it with great readiness, even when largely diluted. 6Ag + 8HNO3 = eAgNOj + 4HjO + NjOj. In order to give it the necessary hardness for use in the arts, it is usually alloyed with copper. Coin silver contains 10 per cent, of copper. Z50 MEDICAL CHEMISTRY. 376. Silver Chloride (AgCl) is formed whenever hydro- chloric acid or a soluble chloride is added to aqueous solutions of silver salts, as a curdy, white precipitate. •AgNOg + HCl = AgCl + HNO3. It is insoluble in acids, soluble in solutions of alkaline chlorides, hyposulphites, and cyanides, and freely so in ammonium hydrox- ide. It may be cr)stallized from ammoniacal solutions in large regular octahedra. 377. Silver Bromide (AgBr) precipitates from solutions of silver salts on the addition of bydrobromic acid or a soluble bromide. AgNOg + HBr = AgBr -|- HNO3. With the exception of not being quite so soluble in ammonium hydroxide, it very closely resembles silver chloride. 378. Silver Iodide (Agl) — Argenti lodidum (U. S. P.)— differs from the chloride and bromide in its yellow color, and insolubility in ammonia. Actinic rays of light change the color of silver chloride, bromide, and iodide, first to violet, then brown, and finally black. The bromides and iodides are more sensitive to light than the chloride. 379! Silver Oxide — Silver Monoxide — Silver Protox- ide — Argenti Oxidum (U. S. P., Br.), (Ag-^O) — is precipitated from solutions of soluble silver salts by sodium or potassium hydroxide, as a dark brown, faintly alkaline powder, slightly soluble in water. zAgNOa + 2KOH = Agp + 2KNO3 -1- HjO. It has strong basic properties. It readily gives up its oxygen when heated. It should not be triturated with substances which are readily oxidizable, or combustible, as it is easily reduced. When the solution in ammonium hydroxide is evaporated, there separate black crystals of an explosive compound (AgjO.zNHg), which, when dry, explode on the slightest disturbance. Silver Suboxide (AgjO) and Silver Peroxide (AgO, or AgjOa) are also known. 380. Silver Nitrate— Argenti Nitras (U. S. P., Br.), (AgNOs)' — is prepared by dissolving pure silver in somewhat dilute nitric acid, evaporating, recrystallizing, and washing with strong nitric acid. It separates in large anhydrous plates, soluble at ordinary temperatures in one part of water or four parts of alcohol, and forming colorless solutions. SILVER. 251 In the presence of organic matter its solutions turn black, and deposit metallic silver on exposure to light. It has been proposed to use this reaction as a test for organic matters in potable waters. Chlorine and iodine decompose .it, with liberation of anhydrous nitric acid, and the formation of chlo- ride or iodide. When fused and cast into cylindrical moulds, it forms the Argenti nitras fusus (U. S. P.), lapis infernalis, or lunar caustic of pharmacy. Argenti nitras dilutus (mitigated caustic) is an official preparation, made by melting together silver nitrate 30 parts, and potassium nitrate 60 parts, and casting into suitable moulds. This salt is also used in photography, in the^manufacture of hair-dyes, marking ink, and in the silvering of glass. 381. Silver Cyanide — Argenti Cyanidum (U. S. P.), (AgCN) — precipitates from silver nitrate solutions as a white, curdy mass, by the addition of potassium or sodium cyanide. It is freely soluble in an excess of the reagent. It is also soluble in ammonium hydroxide and sodium hyposulphite, but is not affected by light. A solution of this compound in potassium cyanide is used as the plating bath in electro-plating with silver. 382. Silver Salts in Photography. — The property of undergoing reduction to the metallic state, by the action o.f light and organic matter, makes the silver salts useful in photography. In taking a photograph, a negative is first prepared, as follows : A plate of glass, previously well cleaned, is evenly covered by floating over it a solution of collodion (a solution of pyroxylin in ether and alcohol) containing a small quantity of iodide or bromide of potassium, and then dried. On dipping the plate into a solution of silver nitrate, it becomes coated with a layer of silver iodide or bromide. After exposure in the camera it is taken to the.dark room and " developed " by pouring upon it a solution of pyrogallic acid, or ferrous sulphate, which reduces the silver salts to the metallic state on that portion of the plate that has been acted upon by light, and makes it opaque. In printing from this, a sheet of albuminized paper, previously floated upon a solution of silver nitrate and then dried, is placed behind the negative and exposed to a strong light. The same action takes place upon the paper; the lights upon the negative becoming dark upon the paper. The image is fixed by dis- solving off the undecomposed silver with a solution of sodium hyposulphite. 252 MEDICAL CHEMISTRY. GOLD (Aurum). Au = 197. 383. Occurrence, — Gold occurs native widely distributed, though in small quantities. It is sometimes found in the form of beautiful crystals, belonging to the cubical system, but gen- erally as metal in quartz. It is also found in the beds of various rivers, in the form of a granular dust. This may be separated by simple washing, the simplest device being the "pan," which is a round dish of sheet iron, with sloping sides, about twelve or fourteen inches in diameter. This pan is about half filled with the mud and sand to be washed, and is held in a stream of water and rotated in such a way that the lighter material is carried away and the gold left. When larger quantities are to be washed, the " cradle" is used. The gold dust so obtained, or the gold quartz which has been pulverized, is treated with mercury, which forms an amalgam with the gold. This amalgam is then placed in a retort and heated. The mercury distils over, leaving the gold behind. 384. Properties. — Gold is orange yellow by reflected light, and green by transmitted light ; very ductile and exceedingly malleable. It fuses at 1200° C. (2192° F.) ; has a specific gravity of 19.36, and is a good conductor of heat and electricity. It retains its luster even at high temperatures. It is not affected by any single acid or alkaline hydroxide. A mixture of nitric and hydrochloric acids readily dissolves it, forming a solution of the chloride. It combines directly with the halogens, phosphorus, antimony, arsenic, and mercury. In handling bromine, care should be taken that its vapor, or the bromine itself, does not come in contact with rings or other gold jewelry, lest they be attacked. 385. Uses. — Gold preparations are not much used in medicine. It is extensively employed, however, in the manu- facture of jewelry and for coinage. For either of these purposes it is too soft to be used alone, but is always alloyed with either copper or silver. In estimating the fineness of gold in jewelry, it is divided into twenty-four equal parts, called carats. The alloy is said to be of so many carats fineness when it contains that number of twenty-fourths of pure metal. Eighteen-carat gold is, then, W gold, and six carats base metal. 386. Aurous Chloride (AuCl) is a pale yellow, insoluble powder, formed by heating auric chloride to 200° C. (392° F.). GOLD. 253 Auri et Sodii Chloridutn (AuCla -{- NaCl) is used in medi- cine. It is a yellow, deliquescent solid, having a saline, metallic taste and acid reaction. It is soluble in water and alcohol. Auriet Sodii Chloridum is not a chemical compound, but a mixture of auric chloride, AuClj, and sodium chloride, NaCl, in equal parts by weight. It is decomposed by heat, and metallic gold separates. 387. Auric Chloride — Gold Trichloride (AuCls) — occurs in deliquescent prisms, soluble in water, alcohol, and ether. With phosphorus or reducing agents it is readily decomposed, with separation of gold. When in solution, it gives, with stannous chloride, a beautiful purple, flocculent precipitate — purple of Cassius — which is used to ornament glass and porcelain. Auric chloride is used in photography for " toning." The silver print is placed in the gold solution and metallic gold is deposited upon the silver picture, thus giving it a " tone." 388. Aureus Oxide (AujO) is a dark violet powder, formed by the action of potassium hydroxide upon aurous chloride. Hydrochloric acid changes it to auric chloride and gold. 389. Auric Oxide (AujO,) is prepared by digesting magne- sium oxide in a solution of auric chloride, decomposing the magnesium aurate by nitric acid, and drying the residue at 100° C. (212 F.). It is a dark-brown powder, which decomposes easily, and unites readily with positive oxides to form aurates having the general formula RAuOj. It will thus be seen, from its behavior with oxygen, that gold in its valence is either monad or triad. GROUP II.— METALS OF THE ALKALINE EARTHS. Beryllium, Be = 9. Calcium , Ca = 40. Strontium, Sr ^87.5. Barium, Ba = 137.2. 390. The metals of this group are called metals of the alkaline earths because their oxides resemble, on the one hand, the oxides of the alkali metals, and, on the other, the real earths (alumina, etc.). Like the potassium group, their properties and chemical energy increase gradually with their atomic weights. Their basic 25 4 MEDICAL CHEMISTRY. properties also become greater with their atomic weights. Thus, barium decomposes water more energetically, and oxidizes more readily, than strontium or calcium. Barium hydroxide is like- wise the strongest base. It is quite soluble in water. It fuses without decomposition, and absorbs carbon dioxide rapidly from the air. Calcium hydroxide possesses weaker basic properties, is difficultly soluble in water, and, when ignited, breaks up into water and calcium oxide. Strontium stands between barium and calcium. Thus, although these metals resemble the alkali metals, both in their free state and as hydroxides, they essentially differ from them in the insolubility of their carbonates and phosphates, and still more their sulphates. Barium sulphate is insoluble in water and acids. CALCIUM. Ca ^ 40. 391. Occurrence. — This metal forms one of a class of ele- ments most widely distributed in nature. Its carbonate (lime- stone, marble, and chalk), its sulphate (gypsum and alabaster), and its phosphate, fluoride, and silicate, are common minerals. Preparation. — Calcium may be obtained from the fused chloride by electrolysis; or, by heating calcium iodide with sodium, or calcium chloride with sodium and zinc. Properties. — A light, lustrous, yellow, ductile metal. It fuses at a red heat, does not sensibly volatilize, and in the air burns with a brilliant reddish-yellow light. It does not undergo oxidation in- dry air, but in moist air covers itself with a layer of hydroxide. Its specific gravity is 1.984. 392. Calcium Chloride — Calcii Chloridum (U. S., Br.), (CaClj) — is prepared by the action of hydrochloric acid upon marble. It crystallizes with 6 molecules of H^O, in large, six- sided prisms, which are bitter, deliquescent, and very soluble in water. If heated, it melts in its water of crystallization with some loss of water. Above 200° C. (392° F.), it becomes anhy- drous. The anhydrous calcium chloride is the official salt. It is a white mass, slightly translucent, having a sharp, saline taste, but no odor. The dry salt is a white, porous mass, which fuses at a red heat and solidifies to a crystalline mass, which rapidly absorbs water, and is used as a drying agent for gases and liquids other than water. Calcium iodide and bromide are very similar to the chloride. The bromide (CaBrj) is official. CALCIUM. 25s 393. Chloride of Lime — Chlorinated Lime — Bleach- ing Powder — Calx Chlorata (U. S., Br.) — is a mixture of calcium chloride (CaCi^) and calcium hypochlorite (Ca(C102)2 with some water. The hypochlorite is the active principle. It is prepared by passing chlorine over slaked lime. From tlie analogous action of chlorine upon sodium or potassium hydroxide, we may express the reaction in the case of calcium hydroxide by the following equation : — 2Ca(0H)j + aCIj = Ca(0Cl)2 + CaQ., + 2H2O. According to this equation, the completely chlorinated chloride of lime must contain 48.9 per cent, of chlorine, which is never the case, as a portion of the calcium hydroxide always remains unchanged. The exact constitution of chloride of lime is in doubt ; but from more recent observations, it is believed by some that the active constituent of chloride of lime is a basic calcium /OCl, hypochlorite Ca^' and the following reaction takes place when chlorine ^OH, acts upon calcium hydroxide: — 3Ca(OH)2 + 2Clj = aCaOjHCl + CaClj + 2H2O. Calculating from this equation, completely saturated chloride of lime con- tains only 39 per cent, chlorine, which is fouud to be actually the case. Chloride of Lime is a grayish-white, porous powder, having a bitter, acrid taste, and a chlorine-like odor ; it is alkaline in reaction, soluble in cold, and decomposed by boiling water. It slowly decomposes in the air, the carbon dioxide liberating hypochlorous oxide ; this decomposition is hastened by sunlight and heat. Ca(C10)2 + CaClj + 2CO2 = zCaCOs + 2CI2O. Dilute mineral acids decompose it very rapidly, with liberation of chlorine. Ca(C10)2 + CaClj + 4HCI = 2CaCl2 -f 2HJ3 + C\^. The application of chloride of lime for bleaching and disin- fecting purposes depends upon this production of free chlorine and nascent oxygen. The amount that will be set free by acids is called the available chlorine, which in good chloride of lime should be at least 25 per cent. The official calx chlorata should contain not less than 35 per cent. 394. Calcium Oxide— Lime— Calx (U. S., Br.), (CaO) — is obtained pure by igniting the carbonate or nitrate. On a large scale, it is prepared commercially by heating the natural carbonate (limestone or marble) in rude stone furnaces, called liiTie kilns. It is a grayish-white, amorphous solid, alkaline and 256 MEDICAL CHEMISTRY. caustic; sp. gr. 2.3; it does not fuse at any temperature at our command. When the oxy-hydrogen flame is thrown upon it, it becomes incandescent, and emits an extremely intense white light. (Calcium, or Drummond, light.) It combines energeti- cally with water to form the hydroxide, the process known as slaking, and is attended with the evolution of much heat. CaO + HjO=Ca(OH)j. It is used for making building mortar. Exposed to the air, it attracts moisture and becomes air-slaked. 395. Calcium Hydroxide — Slaked Lime — Calcis Hy- dras (Br.), (Ca(0H)2 — is a dry, white powder, odorless, and alkaline in reaction. It is slightly soluble in cold and less so in hot water. Exposed to the air, it absorbs carbon dioxide and forms carbonate. Ordinary mortar is a mixture of slaked lime, water, and quartz sand. The hardening of mortar depends upon three causes : ist. The natural evaporation of the water. 2d. The absorption of carbon dioxide from the air, and the forma- tion of calcium carbonate. Ca(OH)j -f CO2 = CaCOj + H^O. 3d. The action of the basic hydroxide upon the silicic acid of the sand, producing calcium silicate. Ca(OH)2 + SiOj = CaSiOs + HjO. This last reaction takes place slowly ; hence the hardness of old mortars. Hydraulic mortar, or cement, contains calcium oxide, aluminium silicate, and quartz powder; its hardening depends principally upon the formation of calcium and aluminium sili- cates. 396. Lime Water — Liquor Calcis (U. S., Br.) — is a clear, saturated solution of the calcium hydroxide in water. The percentage of Ca(0H)2 varies with the temperature. It contains about 0.17 per cent, at the ordinary temperature, but when the temperature rises the solution becomes weaker. Cane-sugar increases the solubility of calcium hydroxide in water, with which it forms a saccharate. The British Liquor calcis saccharatus is a solution of calcium hydroxide in a strong solution of cane-sugar. Syrupus Calcis (U. S. P.) is an analogous preparation. When lime-water contains an excess of the hydroxide, render- ing it turbid, it is called milk of lime. CALCIUM. 257 397. Calcium Sulphate (CaSOi) occurs very abundantly in nature as gypsum, in right rhombic prisms, combined with two molecules of water. The anhydrous salt forms the mineral anhydrite. It is very sparingly soluble in water. One part dissolves at ordinary temperatures in 400 parts H^O. Ground gypsum is used in the arts under the name of terra-alba. When heated to 200° C. (392° F.), it parts with its water, becoming converted into an opaque white mass, which, when ground, is called Plaster-of-Paris. Calcii Sulphas Exsiccatus (U.S. P.), (Dried Gypsum) con- tains about 95 per cent, of CaSOi and about 5 per cent, of water. It is prepared by heating pure Native Gypsum (CaSOi. 2H2O) until about three-fourths of the water is expelled. This powder, mixed with water, takes up two molecules and hardens into a stone-like solid. Upon this property depends the usefulness of plaster for making moulds, iigures, and immovable surgical dressings. 398. Calcium Phosphates — Tricalcic Neutral, or Bone Phosphate — Calcii Phosphas Precipitatus (U. S. P.) — Calcis Phosphas (Br.), (Ca3(P04)2) — is found in rocks and especially in the mineral apatiie, 3Ca3(PO,)2 + CaF„ and in soils, in guano, in the ash of plants, and of every tissue and fluid of animal bodies. It may be prepared pure by dissolving bone ash in hydrochloric acid, filtering, and precipitating with ammonium hydroxide ; Cas,(P0j2 -f 4HCI = CaH^(70^\ + 2CaCIj. CaH4(PO,)j -f 2CaClj -f 4NHiOH = Ca, (POj)^ + 4NHjCl -f 4H2O or, by a double decomposition between calcium chloride and an alkaline phosphate. It is a gelatinous mass when first precipi- tated ; but, after drying, a white, amorphous powder. It is in- soluble in water, but readily soluble in dilute acids, even acetic j also in water charged wiih carbon dioxide. An impure trical- cium phosphate, prepared by burning bones, is known as bone- ash. Dicalcium Phosphate, Ca2H.^(P04)2, separates as an amor- phous insoluble precipitate, when disodium phosphate is added to a strong solution of calcium chloride mixed with a little acetic acid. Monocalcium Phosphate— Acid Calcium Phosphate — Superphosphate of Lime, CaH4(P04)2 — is found in brain 258 MEDICAL CHEMISTRY. tissue and in acid animal fluids. It is produced by the action of sulphuric or hydrochloric acid upon the first two phosphates, and is manufactured as a fertilizer, mixed with calcium sulphate, by decomposing bones with sulphuric acid. Caj(P04)j + 2H2SOt = CaHjCPOj)^ + 2CaS04. At a temperature of 200° C. (392° F.) it splits up into pyrophos- phate, metaphosphoric acid, and water. 2Ca(H,PO,), = Ca^PjO, + 2HPO3 +3H,0. When this mixture is ignited with charcoal, the raetaphosphate is formed and reduced to phosphorus and Cs^CPOi),. 399. Calcium Carbonate — Calcii Carbonas (U. S.,Br.\ (Ca.COa) — is of exceedingly wide distribution in nature. It exists sometimes in enormous deposits, as limestone, marble, chalk, Iceland spar, and as the mineral basis of the corals, shells of the Crustacea, moUusks, etc. Chalk is a comparatively pure, amorphous calcium carbonate, made up of microscopic shells. The precipitated chalk of the Pharmacopoeia is prepared by pre- cipitating calcium chloride with sodium carbonate, filtering off, and washing with water. Prepared chalk — creta preparata (U. S., Br.) — is a native chalk, purified by elutriation, which consists in grinding the chalk in water, allowing the mixture to partially subside, decanting the upper portion, and collecting and drying the finer particles. Calcium carbonate is nearly insoluble in pure water, but dis- solves readily in water containing carbon dioxide ; hence, we find it dissolved in nearly all natural waters, as an acid or bicarbonate (CaH2(C03)2), giving rise to temporary hardness. Boiling, agi- tation, or free exposure to the air may decompose this salt, and deposit the ordinary calcium carbonate. Upon this depends the formation of stalactites, boiler incrustations, and similar deposits. Calcii Carbonas Praecipitatus (U. S. P.) is made by pour- ing together solutions of calcium chloride and sodium carbonate. Double decomposition takes place and CaCOj is precipitated. CaClj -I- Na^COa = CaCOj + 2NaCl. 400. Calcium Oxalate (CaCjO,) is found in the juice of some plants and in the urine. It may be obtained, as a fine, white, crystalline powder, by adding any soluble oxalate to a soluble calcium salt in neutral or alkaline solution, (NHJ^qO, + CaCIj = 2NHiCr-|- CaCjOj. CALCIUM. 259 It is insoluble in water and acetic acid, but soluble in the mineral acids. In many diseased conditions which produce deficient oxidation, or excessive production of acids (lung disease and acid dyspepsia), it occurs in considerable quantities in the urine, and gives rise to oxaluria, or the oxalic acid diathesis. This salt frequently forms calculi, which present irregular projections, and have received the name of mulberry calculi. Excessive saccha- rine diet, or excessive consumption of certain vegetables, as tomatoes, rhubarb, etc., increase the production and elimination of calcium oxalate. Calcii Hypophosphis (U. S. P.), (Ca(PH202)2) is made by boiling together calcium hydroxide and phosphorus until com- bination is complete and phosphoretted hydrogen (PH3) ceases to be evolved. 3Ca(0H), + 8P -1- 6H,0 = 3Ca (PHp,), + 2PH3. The solution is then filtered, evaporated, and granulated. It is generally obtained as a white granular powder, having no odor, but a nauseous, bitter taste. Calx Sulphurata— Crude Calcium Sulphide (U. S. P.). — This is made by mixing together dried calcium sulphate and powdered charcoal, and heating to bright redness in a loosely- covered crucible until the black color of the mixture has dis- appeared. It is a mixture containing about 60 per cent, of CaS with CaSOi and carbon, in varying proportions. It has a pale gray color, and a slight odor of H^S. 401. Physiological Effects and Uses. — The calcium salts play an important part in the animal economy. The phosphates are found in every tissu'e and fluid of the body, but most abun- dant in the bones and teeth ; the former containing from 55 to 59 per cent., and the latter, including the carbonate, 72 per cent. As the salts of lime are insoluble in alkaline fluids, various the- ories have been put forward to explain its state in the blood and other alkaline fluids. It seems certain that the calcium of blood serum does not exist as phosphate, but as some soluble salt or albumin compound, soluble in alkaline fluids.- The calcium phosphate of the urine remains in solution as long as that fluid is acid, but separates as an amorphous or crystalline sediment as soon as it undergoes alkaline fermentation. Alkaline urine is always turbid. When taken internally, the calcium salts produce effects similar to those of sodium and potassium, but milder. They have a mild astringent effect. 26o MEDICAL CHEMISTRY. STRONTIUM. Sr=87.s. 402. Strontium is rather sparingly found in nature. Tlie principal minerals are strontianite (SrCOg) and celestite (SrSO^). It is a brass-yellow lustrous metal, which resembles calcium in its properties, as also do its compounds. This element exhibits most of the properties of calcium and barium. Strontium may be made by decomposing the chloride by elec- tricity. Its compounds impart a red tinge to the flame, and for this reason the nitrate is used as a constituent of red fires. The solubility of its sulphate stands between that of the calcium and barium. It has been used in medicine as an alterative. Its salts are poisonous only in large quantities. The nitrate, Sr(N0s)2, is used in pyrotechnics for making red fire. The bromide, SrBr^, iodide, Srl^, and the lactate, Sr(C3- H50s)2, are official. They are prepared by dissolving the car- bonate in the respective acids. These salts are all soluble in water. BARIUM. Barium is found in nature in the form of BaSOj (barytes), and also as BaCOj (witherite). The element itself is not of interest to the medical student. 403. Barium Chloride (BaClj -f- Aq) is prepared by the action of hydrochloric acid upon the native sulphide or car- bonate. It is used as a reagent for soluble sulphates, giving a white precipitate, insoluble in acids or water. It has been used in medicine as an alterative and anthel- mintic. 404. Barium Oxide — Baryta (BaO) — is obtained by cal- cining the nitrate. , It is a grayish-white, caustic powder, fusible in the oxyhydrogen flame. It unites with water, with the evolu- tion of much heat, to form the hydroxide BaHjOjj this dis- solved in water forms baryta water. Barium Peroxide — Barii Dioxidum (U.S.P.),(Ba02) — is a white powder decomposed by dilute acids, with the production of hydrogen peroxide. It is the only official compound of barium. It is made by heating the oxide to red heat in the air BARIUM. 261 or in oxygen. If the heat is raised too high, the oxygen which was at first absorbed is again given off. 2BaO + 02=2BaOj. 2Ba02 = 2BaO + 02. This power of absorbing oxygen from the air, and giving it off again at a higher temperature, makes it useful in manufacturing oxygen. It is also used for making hydrogen peroxide. 405. Barium Nitrate (Ba(N03)2) — forms anhydrous, octa- hedral crystals of the regular system, soluble in water, and used as a constituent of pale green theatre fires. 406. Barium Sulphate (BaSO,), Heavy Spar or Barite, occurs in nature in rhombic prisms and amorphous ; sp. gr. 4.6. It is obtained by the action of sulphuric acid upon barium salts, as a white amorphous powder, insoluble in acids and water. It is used as an adulterant of white paint, Paris green, and a variety of other commercial products. 407. Barium Carbonate (BaCOs) also occurs native as witherite. It precipitates from solutions of barium salts, as a white amorphous powder, when they are treated with soluble carbonates. 408. Physiological Effect of Barium Salts. — All the soluble compounds of barium, as well as those that are converted into soluble compounds in the stomach, are poisonous. When- ever a poisonous dose has been taken, the patient should take some soluble sulphate (as Epsom or Glauber's salt), followed by ,an emetic. The symptoms of poisoning are pain in stomach, prostration, dilated pupils, loss of voice, sight, or hearing, exces- sive micturition, and other very prominent nervous symptoms. Post-mortem, inflammation and, in most cases, great friability of stomach, and invariably inflammation of the rectum, are found. 262 MEDICAL CHEMISTRY. GROUP II.— METALS OF THE MAGNESIUM GROUP. Magnesium, Mg = 24. Zinc, Zn = 65.2. Cadmium, Cd = 112. Mercury, Hg = 200. MAGNESIUM. Mg = 24. Magnesium was formerly classed with the metals of the alka- line earths, but its sulphate is soluble and its chloride volatile, which, together with its properties in the free state, show it to be more closely related to zinc. 409. Occurrence. — It is found abundantly in nature, usually accompanying calcium. Dolomite, an amorphous mixture of calcium and magnesium carbonates, forms the so-called magnesian limestone. Asbes- tos, serpentine, meerschaum, talc or soapstone, and hornblende are native silicates. Nearly all natural waters contain some of the soluble salts of magnesium, which impart hardness to them. 410. Preparation. — It may be obtained either by electroly- sis of the chloride, or by heating the same compound with sodium. In the arts it is prepared by fusing the double chloride of sodium and magnesium with metallic sodium. MgCljNaCl + 2Na = sNaCl + Mg. It is then purified by distillation in an atmosphere of hydro- gen. 411. Properties. — Magnesium is a brilliant white metal of a sp. gr. of 1.75 ; very tenacious and ductile. It fuses at a dull red heat, and at a bright red heat it distils. It oxidizes but slightly in the air, at ordinary temperatures, but when heated, it burns with an intensely brilliant bluish-white light, owing to the incandescence of the magnesium oxide formed in the burning. The flame of burning magnesium is rich in chemically active or actinic rays; hence, it is much employed for photographing in dark caves and subterraneous chambers. It combines directly with chlorine, sulphur, phosphorus, arsenic, and nitrogen. It is MAGNESIUM. 263 soluble in dilute acids, but not in alkalies. It is slowly oxidized by boiling water. 412. Magnesium Chloride (MgCl2)'exists in small quanti- ties in many mineral springs and in sea-water, to which it imparts a bitter taste. It may be obtained by dissolving the carbonate or oxide in hydrochloric acid. It forms deliquescent crystals, isomorphous with calcium chloride, containing 6 molecules of H2O. The anhydrous chloride is one of the most deliquescent substances known. 413. Magnesium Oxide — Calcined Magnesia — Mag- nesia (U. S., Br.), (MgO)- — is formed by the combustion of the metal, or by the ignition of the carbonate, hydroxide, or nitrate. It is a very light, white powder, without odor or taste, and has a feeble alkaline reaction. It is soluble in dilute acids. A compact variety, prepaied by heating the nitrate or chloride to bright redness, and no higher, exhibits remarkable hydraulic properties. If moistened with water to a paste, it quickly hardens to a compact white solid, of great hardness and durability. If it be mixed with an equal part of marble dust or chalk and moistened, it may be moulded into any desired shape, and on being placed in water, it " sets " into an extremely hard mass. It has been used as a filling for decayed teeth. Magnesia Ponderosa (U. S. P.), or heavy magnesia, does not differ in chemical composition from the light variety, but it differs merely in its physical condition. 414. Magnesium Hydroxide — Hydrated Magnesia Mg(H0)2 — is formed from any soluble magnesium salt by pre- cipitating with sodium or potassium hydroxide. It is almost insoluble in water and alkalies, but .soluble in ammonium salts with the formation of double salts. A mixture holding it in suspension in water, known as milk of magnesia, is used in medicine as a laxative and as an antidote for acid poisons. 415. Magnesium Sulphate — Epsom Salt — Magnesii Sulphas (U. S. P.)— Magnesiae Sulphas (Br.), (MgSOi)— is found in solution in sea waters and in many mineral springs, especially those belonging to the class of bitter waters. It is prepared by the action of sulphuric acid upon magnesium carbonate. At ordinary temperatures it crystallizes with 7 mole- cules of H2O, in four-sided rhombic prisms, very readily soluble in water. When heated, it fuses and parts with its water of crystallization up to 150° C. (302° F.), when it has lost all but one molecule ; this it finally parts with when heated to 200° C. (3gr2° F.). One molecule of water, therefore, is more closely 264 MEDICAL CHEMISTRY. combined than the rest. This is known as the Water of Con- stitution. 416. Magnesium Phosphates. — These resemble the cal- cium phosphates, which they generally accompany in the animal body, though usually existing in smaller quantity. Magnesium also forms double phosphates, one of which, the Ammonio- magnesium phosphate, or triple phosphate (MgNH^ PO4 -f 6H2OJ, is precipitated when an excess of an alkaline phosphate and of ammonia is added to a solution containing magnesium. When the urine becomes ammoniacal from the decomposition of urea, this salt is precipitated, as urine always contains alkaline phosphates and magnesium salts. Being prac- tically insoluble, especially in the presence of excess of phos- phates and of ammonia, it is usually deposited from the urine as a sediment, in the shape of modified right rhombic prisms, which, under the microscope, resemble the shape of a coffin lid. This sometimes takes place in the bladder, and if some body is present that will act as a nucleus, the so-called fusible calculus may form. 417. Magnesium Carbonate — Neutral Carbonate (MgCOu) — occurs in nature as magnesite, and, combined with calcium carbonate, in dolomite. On adding an alkaline car- bonate to an aqueous solution of a magnesium salt, magnesium carbonate is not produced, as most other carbonates would be under similar circumstances, but some carbon dioxide escapes, and a white precipitate falls, which is a mixture of magnesium carbonate and hydroxide, or magnesia alba. 418. Tetramagnesium Carbonate — Magnesia Alba — Magnesii Carbonas (U. S. P.), Magnesiae Carbonas (Br.), (4(MgC03).MgH202 -f 5H2O) — occurs in commerce in light white cubes, composed of an amorphous or pa,rtly crystalline powder. It is prepared by precipitating a solution of magnesium sulphate with one of sodium carbonate. A hot concentrated solution should be used, and the liquid boiled after precipitation. This compound varies in constitution according to the length of time that the boiling has continued and the presence or absence of excess of sodium carbonate. It is very slightly soluble in water, but quite soluble in solutions of ammonium chloride. Magnesii Citras effervescens is a granular salt consisting of citrate of magnesium with an excess of citric acid, and some sodium bicarbonate. When dissolved in water it effervesces copiously, carbon dioxide being evolved. It has a mildly acidu- lous and refreshing taste. 265 ZINC. Zn ^ 65.2. 419. Occurrence. — The native compounds of the heavy metals are termed ores. The most common zinc ores are Smithsonite (ZnCOj.), Calamine (Silicate), and Sphal- erite or Blende (ZnS). These, like most ores, have a high specific gravity, and are usually found in veins in the older crystalline rocks. 420. Preparation. — To obtain the metal, one of its ores, usually the carbonate or sulphide, is converted into an oxide by roasting at a high temperature. This oxide is then mixed with carbon and ignited in cylindrical earthenware retorts, reducing the oxide thus : — ZnO + C = Zn + CO. The free zinc is then distilled off and condensed in iron receivers, which are placed like caps over the opening of the retorts. The metal so obtained forms the spelter of commerce, and con- tains various impurities, such as iron, lead, arsenic, sulphur, and cadmium. Zinc is purified by subjecting it to a second distillation. This is generally conducted in a covered vertical retort, which is pro- vided with a tube which passes through its bottom. The upper end of this tube reaches nearly to the top of the retort, and its lower extremity is just above a vessel of water. When the zinc is heated in this retort, it volatilizes, and passes down the tube, and is condensed in the water. This method is known as "distillation per decentum." 421. Properties — A bluish-white metal, roughly crystalline or granular; its specific gravity is 6.862, if cast ; 7.215, if rolled. It is brittle at ordinary temperatures and can be pulverized ; at 100° C. (212° F.) to 150° C. (302° F.) it is malleable and duc- tile, and may be rolled into thin sheets. At 200° C. (392° F.) it again becomes brittle. It fuses at 412° C. (773° F.), and distils at 1040° C. (1872° F.). In moist air it becomes coated with a thin layer of basic carbonate. When heated in the air, it burns with a very intense bluish-white light, with the formation of oxide. It dissolves readily in dilute acids with evolution of hydrogen. Concentrated sulphuric acid does not dissolve zinc. It is soluble in sodium, potassium, and ammonium hydroxides. On account of the slight action of the air upon it, zinc meets 266 MEDICAL CHEMISTRY. with extensive application in architecture, and for galvanizing or coating iron. Zincum is official in the U. S. P. in the form of thin sheets, or granular pieces, or moulded into pencils, or in powder form. Granulated zinc is made by melting the metal and pouring it into water. 422. Zinc Chloride — Butter of Zinc — Zinci Chloridum (U. S. P., Br.), (ZnClj) — is obtained by heating zinc in a stream of chlorine, by dissolvittg zinc in hydrochloric acid, and by the distillation of zinc sulphate with calcium chloride. It forms a soft white mass, which is very deliquescent, is fusible and volatile. It is extremely soluble in water and freely so in alcohol. The solu- tion has a burning metallic taste, destroying animal and vegetable tissues, and possessing strong dehydrating properties. It forms a series of double salts. The double chloride of zinc and ammonium is sometimes used in soldering, to cleanse the surface of metals to be soldered. 423. Zinci Bromidum (ZnBrj) (U. S. P.) maybe made by dissolving zinc m hydrobromic acid, or by direct combination of zinc and bromine. 2Zn + 4HBr = 2ZnBrj -)- H^. It is a white granular powder, having no odor, but a sharp metallic taste, very soluble in water and in alcohol, and very deliquescent. 424. Zinci lodidum (Znlj) (U. S. P.) may be made by digesting small fragments of zinc in water containing some iodine, or by dissolving zinc carbonate or oxid in hydriodic acid. ZnO -f 2HI = Znlj + H^O. The solutionis filtered through powdered glass and evaporated. It is a deliquescent, granular white odorless powder. Soluble in water and in alcohol. 425. Zinci Phosphidum (ZnsPj) (U. S. P.) is made by passing vapor of phosphorus in a current of dry hydrogen gas over fused zinc. It is a dark gray colored, gritty powder, or frag- ments. It has a metallic luster and a faint odor of phosphorus. Insoluble in water or alcohol. 426. Zinc Oxide— Zinci Oxidum (U. S. P., Br.), (ZnO)— may be prepared by igniting the precipitated basic carbonate, or by burning the metal in a current of air. When obtained in the former way, it forms a soft, white, tasteless, and odorless powder. When produced by burning the metal, it occurs as a white, voluminous, flocculent mass, formerly called flores zinci or ZINC. 267 lana philosophica. It neither fuses, volatilizes, nor decomposes by heat, and is insohible in neutral solvents. It is used in the arts as a white pigment, and is not darkened by hydrogen sul- phide, as is white lead. 427. Zinc Hydroxide (Zn (OHJ2) is formed as a white amorphous powder, by precipitating an aqueous solution of a zinc salt by alkaline hydroxides. It is soluble in excess of alkaline hydroxides and in solutions of ammonium salts. When heated, it decomposes into zinc oxide and water. 428. — Zinc Sulphate— White Vitriol— Zinci Sulphas (U. S. P., Br.), (ZnSOi) — is formed by dissolving zinc, or its oxide, sulphide, or carbonate, in sulphuric acid. 2Zn + 2H2S04 = 2ZnS04 -f 2H,. ZNO + HjSOj = ZnSOj + H^O. ZDCO3 + HjSOi = ZQSO4 + CO, + HjO. At temperatures below 30° C. (86° F.), it crystallizes with 7 Aq. ; at 30° C. (86° F.), with 6 Aq. ; between 40° C. (104° F.) and 50° C. (122° F. ), with 5 Aq. The most common salt is that with 7 Aq., which occurs in rhombic crystals resembling magnesium sulphate, and is freely soluble in water. It is used in medicine as an emetic and astringent. 429. Zinci Acetas (U. S. P.) (Zn (CjHsOj)!), made by dis- solving the carbonate or oxide of zinc in diluted acetic acid, evaporating, and crystallizing. ZnO + 2HC,H30, = ZnCQHjO,), -f H,0. It is in soft, white tablets or scales, having a pearly luster, a faint odor of acetic acid, and a sharp metallic taste. It is soluble in 2.7 parts of water at 15° C. (59° F.), in 1.5 parts of boiling water, and in 36 parts of alcohol. 430. Zinci Valerianas (Zn(C5HA)2.2H20) (U. S. P.) is in white, pearly scales, having a strong odor of valerianic acid, and a peculiar, sweet, styptic, metallic taste. Exposed to the air, it is decomposed, giving off valerianic acid. It is made by mixing hot solutions of sodium valerianate and zinc sulphate, and allowing the zinc valerianate to crystallize out. 431. Zinci Carbonas Precipitatus. This salt is made by mixing a boiling solution of sodium carbonate with a boiling solution of zinc sulphate. Mutual decomposition takes place and ahydrated, basic zinc carbonate is precipitated. 268 MKDICAL CHEMISTRY. SZnSO^ + sNa^COj + sH^O = (ZnCO,),. (Zn(OH)j5, + 5Na,SO, + 3CO,. Precipitated Zinc Carbonate. The precipitate is washed with hot water and dried. It is a white, impalpable powder, odorless and tasteless, insolu- ble in water or alcohol, and of variable chemical composition. The composition of the precipitate varies, according to the tem- perature used. 432. Toxicology. — The compounds of zinc that are soluble in the digestive fluids are all irritant poisons. Solutions of the chloride (used by tinsmiths, in embalming, and as a disinfectant in Burnett's fluid) are also very corrosive. The antidotes are alkaline carbonates, soap, albumin, and mucilage. Solutions containing sodium chloride or organic acids act as solvents upon metallic zinc ; consequently, symptoms of poisoning, more or less marked, are apt to follow eating of acid fruits that have been kept in vessels of galvanized iron. On this account, specimens • intended for analysis, in cases of supposed poisoning, should never be placed in jars closed by zinc caps. Tests. — With alkaline hydroxides and carbonates, solutions of zinc give a white precipitate, soluble in excess of the reagent ; with ammonium sulphydrate or sulphydric acid, in neutral or alkaline solutions, a white sulphide ; with potas- sium ferrocyanide, a yellowish-white precipitate, insoluble in dilute hydrochloric acid. CADMIUM. Cd= 112. 433. Occurrence, Preparation, Properties, etc. — A comparatively rare metal, often accompanying zinc in its ores. Being more volatile than its associate, it accumulates during the first stages of the process of distilling zinc from its ores. It is a soft, white, tenacious metal, of specific gravity 8.6. It alters but little in the air at ordinary temperatures. Heated, it burns, with formation of the oxides, as a brown smoke. It dissolves with difficulty in sulphuric and hydrochloric acids, but readily in nitric acid. 434. — Cadmium Compounds. — These are not very numer- ous or important. As the element is bivalent, they all have the general formula, CdRj. The principal ones are : cadmium hy- droxide (Cd(0H)2), cadmium oxide (CdO), cadmium chloride (CdClii), cadmium iodide (Cdlj), cadmium sulphate (CdSOi), MERCURY. 269 and cadmium sulphide (CdS). The latter is found native in the mineral greenockite. Cadmium iodide and bromide are used in photography. The metal itself enters into the composition of several alloys, which are used for filling teeth, such alloys having a low fusing point. MERCURY (Quicksilver). Hg = 200. 435- Occurrence. — Mercury occurs in nature principally as cinnabar, HgS, or, rarely, in the form of small particles of metal scattered through rocks. It is found in Spain, Peru, China, Japan, California, and Mexico. 436. Preparation. — The native sulphide, or cinnabar, is roasted in reverberatory furnaces, thus burning out the sulphur, and distilling off the mercury and condensing it. Or, it is some- times simply heated with iron, which combines with the sulphur and sets free the mercury, which distils over. Commercial mer- cury usually contains small quantities of other metals, owing to its great tendency to amalgamate with them. To remove these it is re-distilled, or treated with very dilute acids by pouring it in a thin stream into them. When pure, mercury pours from a glass surface without leaving a streak ; t. e., the single droplets retain their globular form, and do not form a tail or adhere to the glass. 437. Properties. — Mercury is the only liquid metal at ordi- nary temperatures. Its specific gravity is 13.596. At — 40° C. it solidifies, and crystallizes in octahedra. It is somewhat vol- atile at ordinary temperatures, and boils at 360° C. (680° F.). Its vapor has a density of 100; specific gravity 6.97 (Air^^ 1). Its molecular weight, therefore, is 200 ; and as its atomic weight is also 200, its molecule, like that of cadmium, is composed of one atom. If pure, and at ordinary temperatures, it is not altered in the air, but at a temperature near the boiling point it becomes coated with a thin film of mercuric oxide. Hot sul- phuric acid converts it into mercuric sulphate, with evolution of sulphur dioxide. It, dissolves readily in dilute nitric, but not in hydrochloric acid. Mercury alloys with and dissolves all metals except iron, to form amalgams. Tin amalgam is used for coating mirrors. Mercury forms two series of compounds, the mercurous and mercuric. The mercurous are less stable, and contain a larger 27b MEDICAL CHEMISTRY. percentage of the metal. They are less soluble, and consequently less poisonous. Mercuric, Mercurous. Mercuric. Mercurous. HgO HgS HgC!, Hg,0 Hg,S Hg,CI, Hgl, HglNOs), HgSO, HgJ, H&(N03), H&SO, 438. Mercurous Compounds. Mercurous Chloride — Protochloride — Mild Chloride — Calomel — Hydrargyri Chloridum Mite (U. S. P.)— Hydrargyri Subchloridum (Br.'), (HgClorHgjCij) — is usually prepared by the mutual de- composition of sodium chloride, mercuric sulphate, and mercury. After mixing thoroughly in a mortar, the mixture is heated, when the calomel sublimes. HgSO< + 2NaCI + Hg = Na^SOj + HgjClj. By this method mercuric chloride is also formed in varying quantities, and should be removed by washing the product with boiling distilled water, until the washings no longer form a pre- cipitate with ammonium hydroxide. Mercuric chloride may be detected in calomel by its forming a black stain upon a bright iron surface dipped in a mixture of calomel and alcohol ; or, by the production of a black stain by hydrogen sulphide in water that has been filtered through calo- mel so contaminated. Calomel crystallizes when sublimed, in radiating quadratic prisms ; but if precipitated from solutions of mercurous salts by hydrochloric acid, it forms a heavy, white, amorphous powder. Heated to about 500° C. (932° F.), it sub- limes without fusing, is insoluble in cold water and alcohol, and dissolves in boiling water to the extent of i part in 12,000. If boiled for a long time with water, it partly decomposes, mercury being deposited, and mercuric chloride passing into solution. Strong acids convert it into mercuric salts and free mercury. With ammonium hydroxide it blackens, with formation of mercurous amidogen-chloride. HgjClj + 2NHpH = NH4CI + NHjHgjCl -|- 2Uf). Hydrochloric acid and alkaline chlorides convert it into mercuric chloride ; this may occur in the stomachs of persons who use large quantities of salted food, as on board ship. Alkaline iodides convert it first into mercurous iodide, which is then decomposed by an excess of the alkaline iodides into mercuric iodide and mercury. MERCURY. 271 439. Mercurous Iodide— Protiodide, or Yellow Io- dide — Hydrargyri lodidum Viride (U. S. P., Br.), (Hgl or Hgzlj) — is prepared by triturating 200 parts of mercury with 127 parts iodine and a little alcohol, until a green paste is formed. It may also be prepared by precipitation from a solution of Hg^CNOs)^ with KI. Hg^CNOa), + 2KI = HgJ, + 2KNO3. It is a greenish-yellow, amorphous powder, insoluble in water and alcohol. It turns brown and volatilizes when heated. Light decomposes it into mercuric iodide and mercury. When moder- ately heated it becomes red, but upon cooling it resumes again its yellow color. But when strongly heated it is decomposed into the red mercuric iodide and mercury. 440. Mercurous Oxide — Protoxide, or Black Oxide (HgjO) — is formed by the action of sodium hydroxide upon mercurous salts. HejfNOj)^ + 2NaOH = HgjO + 2NaN03 -|- H,0. It is a brownish-black, tasteless powder, which sunlight decom- poses into mercuric oxide and mercury. Mineral acids convert it into the corresponding mercurous salts. It exists in the lotio hydrargyri nigri (Br.), or black wash. This is made by adding calomel to lime water. Hg,a, + Ca(OH), = Hg,0 + CaCl, + H,0. 441. Mercurous Nitrate (HgNOj or Hg2(N03)2) is formed by digesting an excess of mercury with a somewhat diluted nitric acid, until short prismatic crystals separate. 6Hg + 8HNO3 = 3Hg,(N03l, + 4H,0 -f- NA- The crystals effloresce in the air. Water decomposes this salt into the acid salt, which goes into solution, and basic mer- curic nitrate ( Hg\ no ) ' ^^ich separates as a yellow powder. Water acidulated with nitric acid dissolves it, but it soon oxi- dizes and becomes mercuric nitrate. By adding metallic mercury to the solution, this oxidation is prevented to a great degree, or, after oxidation, reduces it back to the mercurous Hg(N03)2 + Hg = Hgj(N03),. 442. Mercurous Sulphate (Hg^SOi) is formed by gently warming an excess of mercury with sulphuric acid. It separates 272 MEDICAL CHEMISTRY. as a yellow crystalline precipitale when sulphuric acid is added to a mercurous nitrate solution. 443. Mercuric Compounds. — In these, mercury is biva- lent ; they are represented by the formula HgRj. The mercuric compounds are always formed when mercury is dissolved in excess of acid ; when the opposite is the case, the ous compounds form. The addition of metallic mercury to the mercuric com- pounds converts them into mercurous compounds, while oxidizing agents produce the opposite effect. 444. Mercuric Chloride — Bichloride — Corrosive Sub- limate — Hydrargyri Chloridum Corrosivum (U. S. P.), Hydrargyri Perchloridum (Br.), (HgClj) — may be produced by dissolving mercuric oxide in hydrochloric acid. On a large scale, it is prepared by subliming a dried mixture of mercuric sulphate and sodium chloride. HgSOi 4- 2NaCl = HgCl^ -|- Na^SO^. It crystallizes by sublimation in rectangular octahedra ; from solution, in fine, right, rhombic, needle-like prisms. At ordinary temperatures, it dissolves in 15 parts of water, and at 100° C. (212° F.), in 3 parts; it is still more soluble in alcohol. It dis- solves freely in hot hydrochloric acid, which solution gelatinizes on cooling. Its specific gravity is 5.4. In aqueous solution, it tends to reduce to calomel. Sodium or ammonium chloride prevents this change. Zinc, cadmium, nickel, iron, lead, copper, and bismuth remove most of its chlorine, reducing it either to metallic mercury or calomel. Sulphuric, nitric, and hydrochloric acids all dissolve it without decomposition. When its aqueous solution is treated with a hydroxide of an alkali, or alkaline earth, a yellow precipitate of mercuric oxide (HgO) is formed. This is formed in lotio flava, or yellow wash, which is made by mixing 30 grains of mercuric chloride with a pint of lime water. Mercuric chloride prevents putrefaction. It is an excellent antiseptic, much used in surgical operations. Its solu- tion is used for preserving and hardening anatomical specimens. With albumin, it forms a white precipitate, insoluble in water, but soluble in. excess of albumin solution, or in solutions of alkaline chlorides. 445. Mercur-Ammonium Chloride — White Precipi- tate — Ammoniated Mercury — Hydrargyrum Ammoni- atum (U.S., Br.), (NHuHgCl) — is thrown down as a heavy white MERCURY. 273 precipitate, by adding a slight excess of ammonium hydroxide to a solution of mercuric chloride. HgCIj + 2NHjOH = NHjHgCl + NH^Cl + 2HjO. This salt is sometimes called " amido-chloride of mercury," and may be looked upon as a compound of mercury, chlorine, and amidogen (NHj). Ammoniated mercury occurs in white pulverulent pieces, or in powder. It has no odor, but an earthy and metallic taste. It is used in the official Unguentum hydrargyri ammoniati. It is insoluble in alcohol, ether, and cold water. Hot water decomposes it, with the separation of a heavy yellow powder. It sublimes without fusing. 446. Mercuric Iodide — Biniodide, or Red Iodide — Hydrargyri lodidum Rubrum (U. S., Br.), (Hgl^) — is formed when solutions of mercuric chloride and potassium iodide are mixed. HgCl^ + 2KI = Hgl, + 2KCI. A double decomposition takes place, and the mercuric iodide separates as a yellow precipitate, which immediately turns bright red. It is sparingly soluble in water, but freely soluble in solu- tions of KI and alcohol, forming clear solutions. It also dis- solves in many dilute acids, and in solutions of ammonium salts, alkaline chlorides, and mercuric salts. From its alcoholic solu- tion it crystallizes in bright, red, rhombohedral crystals. When heated, it becomes yellow, fuses, and sublimes in yellow, shining, rhombic needles. These again become red upon touching them with some solid, and are changed into a mass of octahedra. Mercuric iodide is, therefore, dimorphous. Hglj enters into Donovan's Solution. 447. Mercuric Oxide — Red Oxide, or Binoxide — Hy- drargyri Oxidum Flavum (U. S., Br.) — Hydrargyri Oxi- dum Rubrum (U. S. Br.), (HgO) — is obtained by igniting mercurous or mercuric nitrate as long as fumes are given off, 2Hg(N03), = 2HgO -I- 2NA + O,; or, by adding sodium hydroxide to a solution of mercuric salt. HgCl^ + 2KOH = HgO -I- 2KCI + HjO. The product obtained by the first method is red and crystalline, of sp. gr. 1 1. 2; that obtained by precipitation is yellow and amorphous, furnishing Hydrarg. oxid. flavum (U. S. P.). 24 2 74 MEDICAL CHEMISTRY. The latter is the more active form. Both modifications turn black when exposed to the light and air. At 400° C. (725"-F.) they break up into mercury and oxygen. Mercuric oxide is very sparingly soluble in water. It is the chief ingredient of the Lotio hydrargyri flava (Br.), or yellow wash. 448. Mercuric Nitrate (Hg(N03)2) may be obtained by dissolving mercury or mercuric oxide in hot nitric acid. HgO + 2HNO3 = Hg(N03)j + H,0. This should be carefully conducted, as it is inclined to form basic salts. It dissolves in water, and exists in the Liq. hydrargyri nitratis (U. S.;, or Liq. hydrargyri nitratis acidus (Br). . It is used in the volumetric estimation of urea by Liebig's method. The standard solution used for this purpose contains 71.48 grms. of metallic mercury to the liter, and i c.c. precipi- tates 10 mgrms. of urea. 449. Mercuric Sulphate (HgSO^) is prepared by warming mercury or its oxide with an excess of sulphuric acid. Hg + 2HjS0i = HgSOj + SO2 + 2HjO. It is a white, crystalline salt, used as the exciting agent in some forms of galvanic batteries. With an excess of water, it decom- poses into sulphuric acid and the yellow insoluble basic salt, Turpeth mineral, HgS04.2HgO. This is official in the U. S. P. under the names Hydrargyri subsulphas flavus, yellow mercuric subsulphate. 450. Mercuric Sulphide — Red Sulphide — Cinnabar- Vermilion — Hydrargyri Sulphuretum Rubrum (U. S. P.) (HgS) — occurs native in radiating or amorphous masses. It may be prepared by rubbing sulphur and mercury together, or by the precipitation of a mercuric salt by hydrogen sulphide, as a black amorphous mass, which is the ^thiops mineralis of the older pharmacists. HgCl^ + H,S = HgS + 2HCI. This may be converted into the red sulphide by subliming it. Hydrargyri cyanidum Hg(Cn)2 is official. 451. Physiological Action of Mercury. — If introduced into the animal economy, metallic mercury is not poisonous. By contact with alkaline chlorides, however, it is converted into mercuric chloride ; the more finely divided the particles of mer- cury are, the more readily does this take place. Mercuric chloride has a decidedly toxic action, both locally and constitutionally. Its local irritant action is due to its ten- MERCURY. 275 dency to unite with albuminoid bodies. The constitutional symptoms are somewhat similar to those produced by arsenic, but appear sooner. The vomit frequently contains blood, and there is an intense burning, metallic taste in the mouth. The symp- toms that are referable to the gastro-intestinal mucous membrane are more intense. The size of the minimum fatal dose of the corrosive chloride is about three grains ; of white precipitate, thirty to forty grains ; and of Turpeth mineral, about forty grains. Children tolerate mercury much better than adults. The treatment in acute poisoning should consist in the admin- istration of milk or white of egg, and the induction of prompt emesis. Absorbed mercury probably exists in the blood as an albuminate, and is eliminated by the faeces, urine, and saliva ; chiefly by the former. Chronic mercurial poisoning, known as mercurial tremors, shaking palsy, etc., is met with in those who work in mercury compounds. The symptoms usually begin with debility, nausea, vomiting, colicky pains, and a constant metallic taste in the mouth. Sooner or later salivation will become a prominent symptom ; the tongue and gums becoming swollen, red and ulcerated, and the breath will emit aspeculiar fetid odor. Salivation may, however, be produced by bromine, antimony, lead, prussic acid, etc. Chronic and even acute poisoning may occur from the free external use of mercuric salts. Post-mortem the mucous membrane of the stomach, in acute poisoning with HgClj, is usually found of a grayish color, as also that of parts of the mouth and oesophagus. The surface of the membrane is sometimes covered with a slate-colored deposit of finely divided mercury. 452. Tests. — One of the simplests tests for mercury in solu- tion is a piece of bright copper, which, in the presence of a small quantity of free hydrochloric acid, becomes coated with a silver white layer of copper amalgam. All salts of mercury are vola- tile. When heated in a tube with sodium carbonate, globules of metallic mercury distil off from all its salts. Mercury salts give a black precipitate with HjS, which is insoluble in nitric acid but soluble in aqua regia. 276 MEDICAL CHEMISTRY. GROUP III. Boron B= 11. Indium In ^113. Aluminium Al =i 27. Lanthanum La := 139. Scandium Sc = 44. Erbium E^i66. Gallium Ga = 70. Ytterbium Yb = 173. Yttrium Y= 89.8. Thallium Th = ao4. Of the above elements but the first two are of sufficient interest to be described here. BORON. 453. Occurrence and Preparation. — An unimportant ele- ment, never occurring native, but as borates and boric acid. Borates of calcium, magnesiunn, and sodium (borax) occur native ; the last, the most important, is found in India and California. The element maybe prepared in two allotropic states; the first, as a greenish-brown powder, by fusing its oxide with sodium or potassium ; the second, as a crystalline transparent solid, by fus- ing the oxide, chloride, or fluoride with aluminium, varying in color from colorless to a garnet red.. Boron combines directly with nitrogen at elevated temperatures. 454. Boric Anhydride and Acids. — BjOjisa transparent, glass-like mass, obtained by heating boric acid to redness. It is used in blowpipe analysis. Boric or Boracic Acid (H3BO3) exists native in lagoons, in the vicinity of volcanoes, in Tuscany. By evaporation and crystallization the acid is obtained. Borate of sodium or borax occurs in California and India, and from it the pure acid is prepared by precipitating it with HCl from a hot solution. NajBjOj.ioH^O + 2HCI = 2NaCl + 4H3BO3 + sHjO. The acid separates in white, shining scales. It is soluble in 25 parts of H2O at 14° C. (57.2° F.), and in 3 parts of boiling HjO. The solution has a faint acid reaction. The acid is soluble in 6 parts of alcohol, and is also soluble in glycerin, to the flame of both of which it imparts a distinct green color ; this, and the action on turmeric paper, are used as tests. If a strip of turmeric paper be dipped in a solution containing H3BO3,. it turns reddish-brown on drying. ALUMINIUM. 277 When boiled with glycerin, an ether is formed, known as boroglycerid, which is soluble in water, has a neutral reaction, is tasteless, and is used as a preservative for foods. Its use, as well as that of boric acid, is attended, in considerable doses, with an increased excretion of urea, irritation of the kidneys, and should be used with some caution. Owing to its antiseptic action, it is used in surgical dressings. Glyceritum boroglycerini (U. S. P.) is made by dissolv- ing 31 per cent, of boric acid in glycerin. When heated, H3BO3 loses one molecule of water at 100° C. (212° F.), and forms metaboric acid (HBO2) ; on further heat- ing it forms tetraboric acid (H2B4O,), and at a higher temper- ature boric anhydride. ALUMINIUM (Aluminum). Al — 27. 455. This metal is found very widely distributed. It exists as oxide in ruby, sapphire, and corundum, and, less pure, as emery. Most commonly it occurs as the silicate (clay, kaolin), and with other silicates, as feldspar, mica, and in most crys- talline rocks. Emerald is a silicate of aluminium and glucinum. Garnet and topaz are also gilicates of aluminium. Cryolite is a double fluoride of aluminium and sodium. 456. Preparation and Properties. — Aluminium may be obtained in the metallic condition by igniting the chloride, or the double chloride of sodium and aluminium, with sodium. AI2CI5 + 6Na = Alj + 6NaCl. It is a silver-white metal, very malleable and ductile, a good conductor of electricity ; sp. gr. 2.56. At ordinary temperatures it is not affected by air or oxygen, but burns if heated in oxygen. It is insoluble in nitric acid, soluble in boiling sulphuric and cold hydrochloric acids. It dissolves in alkaline hydroxides to form aluminates, with liberation of hydrogen. It forms a hard and durable alloy with copper, known as aluminium bronze. 457. Aluminium Chloride (AljCle) is obtained by the action of chlorine upon heated aluminium. It forms colorless hexagonal prisms, fusible, volatile, and very soluble in water and alcohol. It crystallizes from a hot concentrated solution with 12H2O. 278 MEDICAL CHEMISTRY. 458. Aluminium Oxide — Alumina (AI2O3) — is found Crystallized in prisms, and colored by other admixtures in ruby,- sapphire, and corundum. These minerals are all exceedingly hard, ranking next to the diamond in this respect. Alumina may be obtained artificially, by igniting the hydroxide, as a light, white, insoluble, odorless, and tasteless powder. When prepared as above acids attack it with great difficulty. It may be decora- posed by fusing with caustic alkalies or acid potassium sulphate. 459. Aluminium Hydroxide (Al2(OH)6) is formed by precipitating a solution of an aluminium salt with ammonium hydroxide or carbonate. The Alumini Hydfas (U. S. P.) is directed to be made by precipitating a solution of alum with sodium carbonate. K,A.1,(S0J, + 3Na2C03+ 3H2O = sNa^SO^ + K^SO, + Al^lOH)^ + sCO,. When freshly precipitated it is insoluble in water, but soluble in solutions of the fixed alkalies. By prolonged drying, or after standing under water, it is rendered almost insoluble in acids, although it undergoes no change in composition or appearance. 460. Aluminium Sulphate — Aluminii sulphas (U. S. P.) (Al2(S04)3) — is prepared artificially by the action of sulphuric acid upon kaolin or clay. Also, by dissolving aluminium hy- droxide in the same acid. Al^COH). + sH^SO^ = Al^CSOJ, + eH^O. It crystallizes in thin plates with 16H2O; soluble in water, and sparingly so in alcohol. When heated, it fuses and becomes anhydrous. 461. Alums. These are double salts formed by the combina- tion of aluminium sulphate with the alkaline sulphates. The salt originally known as alum is the double sulphate of alumin- ium and potassium (K2Al2(S04)4. 24H2O). It is obtained from clays free from iron, and from aluminite, a basic sulphate of aluminium. The potassium in this alum can be replaced by sodium, ammonium, rubidium, caesium, and thallium. Potas- sium alum forms large, regular, transparent, octahedral crystals, soluble in water. Heated to about redness, it loses 45 per cent, of its weight of water, forming the product known as burnt alum. Aluminium and ammonium sulphate, or ammo- nia alum, Al2(SO«)3.(NH4)2S04.24H20, is rapidly taking the place of the potassium alum, from which it differs in being more soluble in water between 20° C. (68° F.) and 90° C. (104° F.), and less soluble in water colder or warmer than this. At about CHROMIUM. 279 the temperature at which potash alum loses its water, ammonia alum decomposes and loses its ammonia. Ferric iron, manga- nese, and chromium may replace the aluminium in alum, and form a series of alums known as ferric alum, Fe2(S04)3(NH4)2- S0424H20, manganese alum, and chrome alum. Cr2(SOj3.(NHj2SO„24H20. Mn2(SOj3,(NH4),SOi,24HjO. METALS OF GROUP V. Vanadium V :^ 51. Niobium Nb = 94. Didimium Di ^ 145. Tantalum Ta = 182. They are all rare metals not used in medicine. METALS OF GROUP VI. Chromium ... Cr = 51. Molybdenum . . Mo = 94. Wolfram (Tungsten) VJ = 184. Uranium U ^ 240. Of these chromium and molybdenum will be noticed at length. CHROMIUM. Cr = 52.4. 462. Occurrence, Preparation, and Properties. — This metal most commonly occurs in chromite, or chrome iron ore, a ferroso-chromic oxide; also, rarely, as lead chroraate. It may be isolated with difficulty from its oxide by reducing with char- coal ; or from the chloride by reducing with zinc. It is a hard, glistening, steel-gray metal, magnetic at low temperatures ; sp. 28o MEDICAL CHEMISTRY. gr. 6.8. It oxidizes only at a red heat, and is soluble in hydro- chloric acid and strong alkalies. 463. Chlorides. Two chlorides are known : Chromous Chloride (CrClj), a white, crystalline solid, dissolving in water to forma blue solution, and chromic chloride (CrjCle), occur- ring in large red crystals, insoluble in water, unless a trace of the chromous chloride be present, when it dissolves readily. If it be subjected to a prolonged boiling with water, it finally dis- solves, forming a green solution containing a hydroxide. An oxychloride is also known. 464. Chromic Anhydride — Chromic Trioxide (CrOj). — This is sometimes improperly called chromic acid. It is pre- pared by adding one and one-half parts strong sulphuric acid to one part of concentrated solution of potassium dichromate. When the solution cools, splendid saffron-colored needles of the trioxide crystallize out, which may be dried on a porous tile. It is a powerful oxidant, igniting alcohol if the latter be poured upon it. It is used in medicine as a caustic, forming a super- ficial eschar. 465. Chromic Oxide — Chromium Sesquioxide — Green Oxide (CrJ'Oa) — is obtained by calcining a mixture of starch and potassium dichromate. Thus prepared, it is a green powder, insoluble in water, acids, or alkalies, and fusible with difficulty. When fused with alkaline hydroxides or nitrates, it forms chro- mates of these metals. This oxide may play either a positive or negative r61e, depend- ing upon the oxide with which it unites. For example, with the strongly negative sulphuric oxide, it forms chromium sulphate (Cr2(S04)3) ; while with calcium or magnesium oxide, calcium or magnesium chroraates (CaCrO^ or MgCr04) are obtained. 466. Chromous Hydroxide (Cr(0H)2). — This compound is produced by precipitating chromous chloride by potassium hy- droxide. It acts as a basic oxide, yielding chromous salts. 467. Chromic Acid (HjCrO^). — This cannot, be isolated, but by solution of chromium trioxide in water, an acid liquid is obtained containing chromic acid. This acid decomposes on evaporation. The best known of the salts of this acid are potassium chro- mate and dichromate (K^CrO, and KjCrjO,). The last of these possesses the properties of the trioxide, but in a milder degree. It is sometimes used as an escharotic, but much more frequently as an oxidizing agent, when mixed with sulphuric acid. None of CHROMIUM. 281 the other preparations of chromium are used in medicine. Inter- nally, in large doses, it acts as an irritant poison. 468. Chromic Sulphate (Cr2(S04)3) is obtained by dissolv- ing chromic oxide in sulphuric acid ; upon slowly evaporating, it crystallizes with twelve molecules of water. Chromium salts form two series, the one green and the other violet. The alkaline hydroxides throw down a bluish-green hydroxide from the green salts, and a violet from the violet. Chromium sulphate exists as a violet crystalline solid, and as a green amorphous solid. With the alkaline sulphates, chromium sulphate forms double salts — the chromium alums. (See Art. 461.^ 469. Potassium Chromate (KjCrO,) is obtained by adding a solution of potassium hydroxide to one of potassium dichromate. KjCr^O, -I- 2KOH = zK^CrOj -f Bfi. It forms large, yellow, rhombic crystals, isomorphous with potas- sium sulphate (K2SO4). 470. Potassium Dichromate (KjCrjO,), commercially known as the red chromate of potash and often called the acid potassium chromate, is obtained by igniting pulverized chromite (CrjOgFeO) with potassium carbonate and nitrate, forming potassium chromate and ferric oxide. The potassium chromate is dissolved out with water, and nitric or acetic acid added to the solution, from which potassium dichromate crystal- lizes. It forms large, red prisms, soluble at ordinary tempera- tures in ten parts of water. When it is warmed with sulphuric acid, oxygen escapes, and chromic oxide and potassium chrome alum are produced. This mixture is employed in laboratories for oxidizing purposes. Barium chromate (BaCrO^), and lead chromate (PbCrO^) are used as yellow pigments ; the former under the name of yellow ultramarine and the latter as orange chrome. ^Ji. Toxicology. — The chromates, especially potassium dichromate, are irritant poisons. They are also liable to pro- duce a form of chronic poisoning in workmen handling them, characterized by ulceration of the septum of the nose, and of the skin. The most prominent symptoms in acute poisoning are vomiting, epigastric pain, cramps, excessive thirst, and collapse. The treatment consists in the use of emetics, followed by magne- sium carbonate in milk. 282 MEDICAL CHEMISTRY. MOLYBDENUM. Moi=>96, This element is of little importance itself, but some of its compounds are used. 472. Molybdic Trioxide or Anhydride (M0O3). — This oxide is obtained by roasting the native sulphide in an open vessel, at a red heat. The principal interest attached to it, is its use in preparing ammonium molybdate, a reagent used to detect and estimate phosphoric acid. The impure oxide obtained by roasting the mineral molyb- denite, M0S2, is dissolved in ammonium hydroxide, evaporated to dryness, re-dissolved in water, concentrated by evaporation, and allowed to crystallize. The soluble molybdates give a pre- cipitate of M0O3 on the addition of acid ; but it is soluble in excess of acid. The molybdates give a white precipitate with the earthy metals. With phosphoric acid or the phosphates, a solution of ammonium molybdate containing an excess pf nitric or hydrochloric acid first turns yellow, then deposits a yellow precipitate of molybdic trioxide, phosphoric acid, and ammonia, which is very soluble in ammonia water. This is a very delicate test for phosphoric acid. Pyrophosphates and metaphosphates do not give this reaction. Arsenic acid gives a similar precipitate. TUNGSTEN (Wolfram;. W=j84. 473. Tungsten is not abundant. It occurs in the minerals wolframite, schulite, and stolzite, all of which are tung- states. Although generally regarded as a metal, it often plays the negative role to form tungstic acid and tungstates. The element is a hard, brittle, difficultly fusible metal, perma- nent in air, but burns to oxide at a red heat. Of the compounds of tungsten, the sodium tungstate alone is of interest to the medical student. Tungstic Acid (HjWOi) is a yellowish-white powder thrown down from boiling alkaline solutions of tungstic oxide by mineral acids. It forms with bases numerous salts, called tungstates, the most important of which is sodium tungstate (Na2W04.2H20). This has recently attained considerable importance as a -test for albumin in urine. A cold saturated solution of this salt, added to acid solutions of the proteids, coagulates them. This salt is used to render fabrics uninflammable. MANGANESE. 283 GROUP VII.— METALS. MANGANESE. Mn = 55. 474. Occurrence. — Manganese is found widely distributed in nature. It occurs native in meteorites. Its most common ores are pyrolusite (MnOj), hausmanite (MnjOj), braunite (MnjOa), manganite (MnjOs.HjO), and rhodochrosite (MnCOa). 475. Preparation and Properties. — It is obtained in the metallic condition by heating its oxides with charcoal, similar to the smelting of iron. A grayish-white, brittle metal, very hard, and fusing with great difficulty ; sp. gr. 7.2. Like the elements iron and chromium, it forms three series of compounds — the manganous (MnRj), manganic (Mn^Rg), and the salts of man- ganic acid, called manganates. 476. Manganous Compounds. — In these the metal is dia- tomic. These derivatives are the most stable and constitute the most common of the manganese salts. They resemble the ous salts of iron and chromium, with which they are isomorphous. Manganous Oxide (MnO) results from ignition of the carbo- nate with exclusion of air. It is a greenish, amorphous powder, readily oxidizing in the air to MnsOi- Manganous hydroxide (Mn(0H)2) is formed by adding alkaline hydroxides to manga- nous solutions, as a reddish-white precipitate, which, exposed to the air, oxidizes to manganic hydroxide, and turns brown in color. 477. Manganous Salts. — Manganous Chloride (MnClj) pccurs in rose-colored tabular crystals, which decompose on drying, with separation of hydrochloric acid. Manganous Sulphate (MnSOj) crystallizes at ordinary temperatures with 5H2O. It is official. It occurs as colorless or pale rose-colored, prismatic crystals soluble in 0.8 part of water at 15° C. (59° F.) and in i part of boiling water. With the alkaline sulphates it forms double salts; e. g., MnSO4.K2SO4.5H2O. Manganous Carbonate (MnCOs) is precipitated from manganous solutions by alkaline carbonates as a white powder, turning brown on exposure to air. Manganous Sulphide (MnS) occurs in nature as alabandite, or manganese blende, and is precipitated from manganous solutions by alkaline sulphides as a flesh-colored hydrate (MnS.HjO). In the air it also becomes brown. 284 MEDICAL CHEMISTRY. 478. Manganic Compounds. — These are isomorphous with and very closely resemble the ferric, chromic, and aluminic com- pounds. They are not so stable, however, being easily reduced to the manganous state. ■ In them manganese is a tetrad. 479. Manganese Dioxide — Manganic Peroxide — Black Oxide of Manganese (MnOj) — occurs native as the mineral pyrolusite, the principal ore of manganese, in steel-gray or brownish, imperfectly crystallized masses. When gently heated, it yields oxygen ; at a red- heat, it yields more oxygen and forms manganous-manganic oxide. SMnO^ = MogO^ + Oj. It gives off oxygen when heated with sulphuric acid, and forms manganous sulphate. With hydrochloric acid, it yields manga- nous chloride, water, and chlorine. MnOj -f 4HCI = MnClj, -f zUf) -f Clj. In cold hydrochloric acid, it dissolves without setting chlorine free, as MnCli is probably formed, which, upon heating, breaks up into MnClj and Clj. From this it would appear that, in the dioxide, manganese is a tetrad. Manganic Oxide (MnjOj) is a black powder, produced by igniting the manganese oxides in a current of oxygen. Manganous-manganic Oxide (MnjOi^ MnO,Mn203). — This is formed by the ignition of all the oxides in the air; it is isomorphous with Magnetite (FejOj). 480. Manganic Hydroxide, (Mn2(OH)6) is precipitated from manganic solutions by ammonium hydroxide as a flesh- colored precipitate, rapidly turning brown. Manganic Sulphate (Mn2(S04)3) is produced by the action of sulphuric acid upon manganic hydroxide. 481. Manganates and Permanganates. — The derivatives of manganic acid (HjMnO^ = MnOjCOH)^) are analogous to those of ferric (HjFeOj), chromic (HjCrOi), and sulphuric acid (H2SO4). In these derivatives, manganese is a hexad. The manganates are of little permanency and little used. Potassium Manganate (KjMnO^) is a rare substance, iso- morphous with potassium sulphate ^or chromate, and is very readily converted into potassium permanganate. 482. Potassium Permanganate "(KMnOj) or (KaMn^Os) (U. S. P.) is precipitated from solutions of potassium manganate by acids, in dark-red, rhombic prisms. It is made by boiling in IRON. 285 water, potassium hydroxide, potassium chlorate, and manganese dioxide, evaporating to dryness, and fusing. 6K0H + KCIO3 + aMnOj = sKjMnO^ + KCl + sH^O. A greenish-colored mass — potassium manganate — is formed. This is dissolved in water, and is then easily decomposed by an acid or a large quantity of hot water. aKjMnOj + sHjO = K^MdjOs + MnO^ + 4KOH + HjO. Manganese dioxide is precipitated, and the permanganate re- mains in solution, from which it is obtained by crystallization. This salt has active oxidizing properties, and is very largely used for oxidizing and destroying organic substances. It also converts ferrous into ferric salts, and is used for the quantitative estimation of ferrous salts because of this property. Also used to estimate organic matter in potable waters. Condy's fluid is an aqueous solution of KjMnjOg. GROUP VIII. The members of the group are — Iron (Ferrum) Fe= 56. Rhodium Rh = 104. Nickel . . . Ni = 59. Palladium Pd = 106. Cobalt . . .Co= 59. Iridium . . Ir = i93. Ruthenium Ru = 103. Osmium . Os ^ 195. Platinum Pt ^ 195. Of these, iron, nickel, cobalt, osmium, and platinum are of sufficient interest to be given a place here. IRON. fc = 56. 483. Occurrence. — This metal, which is of so great practi- cal importance, is distributed very widely in nature. It occurs native upon the earth's surface only as meteorites. The ores from which iron is obtained are numerous; the most important are: magnetite (FeaOi), haematite (Fefi,), limo- nite (ferric hydroxide), and siderite (FeCOj). These are almost the only ores used for the manufacture of iron; the sulphur ores are not adapted to this purpose. 286 MEDICAL CHEMISTRY. 484. Preparation. — In some cases the ore is first roasted, to get rid of water, carbon dioxide, sulphur, etc. The next step consists in the extraction of the iron from the ores, in which it exists as oxide. This is accomplished by reduction with carbon, at a glowing heat. This reduction is effected in a blast fur- nace (Fig. 54), of which the interior has the shape of a double cone. It is about fifty or sixty feet high, by fifteen feet wide at its widest part, is built of the most infusible fire brick, and inclosed in solid masonry. It is filled at the top with alternate layers of coal, broken ore (either native or previously roasted), and fluxes in the form of limestone or silicates. These fluxes facilitate the melting together of the reduced iron, and furnish a liquid slag. The air necessary for combustion, usually heated to a high temperature before- hand, is forced into the bottom of the furnace, through pipes, by blow- ers or fans. The metal is drawn off at the bottom. In the lower part of the furnace, carbon dioxide is pro- duced froth the oxygen of the air and the coal ; higher up, carbon monoxide is produced, which acts upon the oxide of iron, reducing it to the metallic state. As the reduced iron sinks, it comes into contact with the coal, takes up a small quantity of carbon, and forms cast-iron, which, on further sinking, fuses, and is drawn off into moulds made in sand, to form pig iron. The earthy impurities of the ores, remaining in the furnace, unite with the fluxes, fuse in the intense heat, and are drawn off as slag. The pig iron is then subjected to the puddling process, by which it is more completely freed from carbon and slag, and wrought iron results. This process is usually carried on in reverberatory furnaces with a free supply of air, while the molten mass is being thoroughly stirred. The greater part of the carbon is in this way burned into carbon monoxide, and the silicon, sulphur, and phosphorus oxidized. Steel was formerly prepared from wrought iron only, by cementation, or heating wrought iron, packed in leather shavings or with charcoal. At BLAST FURNACE. IRON. 287 present it is chiefly prepared directly from cast or pig iron by the method invented by Bessemer in 1850. This process consists in blowing air, under high pressure, into a mass of molten cast-iron, until the carbon has been burned out, when spiegeleisen, contain- ing a known quantity of carbon, is added, to give the proper amount for steel. Pure iron is obtained by heating ferric oxide in a current of hydrogen ; this is the ferrum redactum of the U. S. P. FeA -I- 3H,-= 3H,0 -f Fe,. 485. Properties. — Pure iron is soft, fuses at about 1600° C. (2912° r.), and has a specific gravity of 7.25 to 7.9. Iron is not affected by dry air at ordinary temperatures; in moist air, it covers itself with a thin layer of ferric hydroxide, known as rust. Heated strongly in the air, it becomes coated with a layer of ferrous-ferric oxide (FesOj), which is readily loosened, forming the blacksmith's scales. At a red heat, it decomposes water, with the formation of ferrous-ferric oxide, and the libera- tion of hydrogen. 3Fe + 4H2O = Fefi^ + 4Hj. It burns in oxygen with an intense, scintillating light. If brought into contact with a magnet, iron becomes magnetic. Tempered steel is the only form, however, that retains the mag- netism. Iron unites directly with chlorine, bromine, iodine, sulphur, and the members of the phosphorus group, except nitrogen. It dissolves readily in hydrochloric and sulphuric acids, with evolution of hydrogen. In dilute nitric acid, it dissolves with separation of nitric oxide. Concentrated. nitric acid, however, renders it passive, when it is no longer attacked by the dilute acid, until the passive condition is destroyed by contact with silver, platinum, or copper, or by heating to 40° C. (104° F.). 486. Ferrous Compounds. — These are formed by dis- solving iron in an acid, or by the reduction of ferric salts. FejClj -I- Zn= (FeCl,)^ -|- ZnCIj. They are usually of a green color in the hydrous state. Exposed to the air, they oxidize to ferric salts. 4FeO + Oj = 2FeA. 487. Ferrous Chloride (FeClj) is formed when iron is dis- solved in hydrochloric acid. It crystallizes in green mono- 288 MEDICAL CHEMISTRY. clinic prisms, containing four molecules of water. Exposed to the air, they deliquesce and oxidize, forming ferric chloride and an oxychloride. The anhydrous chloride is formed by passing hydrochloric acid gas over iron that is heated to redness, as a volatile, yellowish-white, very soluble solid. 488. Ferrous Iodide — Ferri lodidum (Br.), (Felj) — is obtained in solution by adding an excess of iron to iodine sus- pended in warm water, until the solution is pale green. Ferri lodidum Saccharatum — Saccharated Ferrous Iodide (U. S. P.) — is made by reacting upon iron with iodine in the presence of water, evaporating the solution to dryness, and mixing with sugar of milk. Syrupus Ferri lodidi is also official. It contains about 10 per cent, of Felj. 489. Ferrous Oxide (FeO) is a black powder, produced by the reduction of ferric oxide by carbon. It easily oxidizes again. Ferrous Hydroxide (Fe(0H)2) is precipitated from ferrous solutions, by alkaline hydroxides, as a white powder. It also oxidizes readily, becoming green, and then brown. 490. Ferrous Sulphate — Protosulphate of Iron — Green Vitriol — Copperas — Ferri Sulphas (U. S. P., Br.), (FeSOi.yHjO) — is obtained pure by dissolving iron in dilute sul- phuric acid. Fe + HjSO^ = FeSOi + H,. For commercial use it is obtained from pyrites (FeSj) by oxida- tion, and as a by-product in other processes. It forms oblique rhombic prisms. At a red heat it decomposes into ferric oxide, and sulphur di- and trioxides. On this property is based the production of fuming, or Nordhausen sulphuric acid. Green vitriol has an extended use in the arts. Among other uses, it is employed in the manufacture of ink, and as a mordant in dyeing. . Ammonio-ferrous Sulphate (Fe(NH4)2(S04)2.6H20) is a green, crystalline salt resembling the sulphate. It is more stable than ferrous sulphate. 491. Ferrous Carbonate (FeCOj) exists in the mineral, siderite. It may be obtained by adding sodium carbonate to ferrous solutions. FeSOj -I- NajCOg = FeCOj + Na^SO^. It is rapidly changed to ferric hydroxide on exposure to the air ; is insoluble in pure water, but soluble in water containing IRON. 289 carbon dioxide, and is, therefore, present in many natural waters. Ferri Carbonas Saccharatum (U. S. P.) is ferrous carbo- nate to which sugar has been added to prevent decomposition, and is prepared by mixing solutions of ferrous sulphate and sodium bicarbonate and adding sugar ; the mixture is then evaporated to dryness. It is a greenish-gray powder. 492. Ferrous Phosphate — Triferrous Phosphate (Fca (POi)^) — is a white precipitate formed by adding sodium phos- phate to a solution of a ferrous salt. It turns blue on exposure to the air, a part being converted into ferric phosphate. It is insoluble in water; slightly soluble in water containing carbon dioxide or acetic acid. A soluble or acid phosphate exists in the shops. A phosphate of iron, that turns blue on exposure to the air, exists in the lungs in phthisis, in bones which have been buried for some time, and occasionally in pus. 493. Ferrous Sulphide — Protosulphide (FeS) — may be obtained, first, by fusing a mixture of sulphur and iron filings, although the union will often occur slowly at ordinary tempera- tures; second, by precipitation of a ferrous salt with alkaline sulphides. The first method forms brownish, brittle, fusible masses ; the latter yields a black powder. Ferrous sulphide is not decomposed by heat, but is decomposed by sulphuric acid, with formation of ferrous sulphate and hydrogen sulphide. It occurs in the faeces of persons taking chalybeate waters and prep- arations of iron. 494. Ferrous Lactate — Ferri Lactas (U. S. P.), (Fe(C3 HsOs^j -}- 3H2O — is obtained by dissolving iron filings in lactic acid. It forms light yellow crystals, soluble in water, insoluble in cold alcohol. 495. Ferrous Oxalate (FeCaOj) is made by dissolving iron in a solution of oxalic acid. A bright yellow, crystalline powder, slightly soluble in hot water. 496. Ferrous Tartrate (FeQHjOs) is formed by dissolving iron in a hot, strong solution of tartaric acid. 497. Ferric Compounds. — Ferric Chloride — Sesqui- chioride of Iron — Perchloride of Iron — Ferri Chloridum (U. S. P.), (FjCle) — may be obtained in anhydrous volatile, deliquescent plates by heating iron in chlorine gas. It may be formed in solution by dissolving iron in hydrochloric acid and adding a little chlorine water or nitric acid ; or by dissolving the oxide or hydroxide in hydrochloric acid ; or by the action 25 290 MEPICAL CHEMISTRY. of chlorine on a solution of ferrous chloride. To obtain the solid, it is only necessary to evaporate and crystallize. It forms yellow, crystalline masses or rhombic plates, readily soluble in water, alcohol, or ether. The Liq, ferri chloridi CU. S. P.), or Liq. ferri perchloridi (Br.), is an aqueous solution containing an excess of acid. The U. S. P. preparation contains 37.8 per cent, of ferric chloride. The Tinct. ferri chloridi (U. S. P.) is the same, diluted with alcohol, and contains also ethyl chloride and ferrous chloride. It contains about 13.6 percent, of Fe2Cl6. 498. Ferric Oxide— Sesquioxide of Iron (FejOs) — exists in nature as haematite, and may be formed by heating the oxy- gen compounds of iron in the air. On a large scale, it is ob- tained by distilling ferrous sulphate, which first turns white, from loss of water ; then yellow, owing to the formation of an oxyhydrate, and finally to a brick-red, ferric oxide. It is used as a polishing material, under the names of colcpthar, red crocus, jeweller's rouge, or caput mortuum. Ferrous-ferric Oxide (FcsO^^ FeCFezOj) occurs native as magnetite. It may be obtained artificially by conducting steam over ignited iron. It constitutes the natural magnets. 499. Ferric Hydroxide — Ferri Oxidum Hydratum (U.S. P., Br.), (Fe2(OH)6) — is a voluminous, reddish-brown, gela- tinous mass, precipitated by alkaline hydroxides from ferric solu- tions. When dried at 100° C. (212° F.), itloses 2H2O. Freshly precipitated ferric hydroxide is soluble in a solution of ferric chloride or acetate, and if such a solution be dialyzed, the iron salt diffuses, leaving the pure ferric hydroxide on the dialyzer. The dialyzed iron so obtained is coagulated by heat, acids, or alkalies into a jelly-like mass. It is a good antidote in arsenic poisoning. 500. Ferric Sulphate (Fej(S04)3) is obtained bj dissolving the oxide in sulphuric acid. It remains, after evaporating the solution, as a white mass, which dissolves readily in water, form- ing the Liquor ferri tersulphatis (U. S. P.). This solution is a dark, reddish-brown liquid, having an acid, styptic taste. Another sulphate, which is basic, is formed by treating ferrous sulphate, 77 parts, with nitric acid, and evaporating, after add- ing 7 parts sulphuric acid. This, in solution, is the Liq. ferri subsulphatis, or Mon- sel's solution, Fe40(SOi)5. IRON. 291 501. Ferric Alum — Ammonio-ferric Alum — Ferri et Ammonii Sulphas (U.S. P.), (NH4i2Fe2(S04)4.24H20)— is prepared by adding a solution of ammonium sulphate to a solu- tion of ferric sulphate, and evaporating down and allowing it to crystallize. The crystals are colorless or pale amethyst, regular octahedra, soluble in 3 parts of water at 15° C. (59° F.). The solution has an acid reaction and an astringent taste, but not so astringent as ferric sulphate. It gives the reactions for ferric iron, ammonia, and sulphates. It is employed in medicine as an astringent, both internally and locally. 502. Ferric Nitrate (Fe2(N03)6) is formed, together with ferrous nitrate, by dissolving iron in nitric acid. The Liq. ferri nitratis (U.S.P.), or Liq. ferri pernitratis(Br.),isan aqueous solution of ferric nitrate, containing about 6.2 per cent, of Ye,- (N03\. Ferric nitrate crystallizes in rhombic prisms with 18H2O, or in cubes with 12H2O. 503. Scale Compounds of Iron. — -These are certain salts of iron, mostly with organic acids, which do not crystallize readily, but are put into the market in the form of thin scales. They are prepared by evaporating their solution to a thick, syrupy consistence, spreading upon glass plates, drying, and then detaching the thin scales from the glass. They are all used in medicine. 504. Ferri Citras (U. S. P.) — citrate of iron — is prepared by dissolving freshly precipitated ferric hydroxide in a solution of citric acid, and evaporating the solution to the proper consistency and scaling. After its aqueous solution has been evaporated upon glsiss, it forms beautiful, thin, transparent scales, of a gar- net-red color, slowly soluble in cold, but freely in hot water, and possessing a mild, chalybeate taste. 505. Ferri et Ammonii Citras (U. S. P.) — citrate of iron and ammonia — is formed by treating a solution of citrate of iron with ammonium hydroxide, and evaporating at a temperature that should not exceed 38° C. (100.4° F-)- It also forms garnet-red scales, which are readily and wholly soluble in water, forming a solution that is neutral to litmus paper and slightly styptic in taste. 506. Ferri et Ammonii Tartras (U.S. P.) — tartrate of iron and ammonia, a double -salt — is formed by the action of tartaric acid upon ferric and ammonium hydroxides. Upon evaporating its solution, garnet-red scales remain, which are slowly soluble in water. Their solution is neutral to test paper, and is of a sweetish, rather pleasant taste. 292 MEDICAL CHEMISTRY. 507. Ferri et Potassii Tartras (U. S. P.) — Ferrum Tar- taratum (Br.) — potassio-tartrate of iron — maybe obtained by dissolving ferric hydroxide in a solution of acid tartrate of potassium, and evaporating on glass. It forms ruby red scales, having about the same properties as the ammonio tartrate. 508. Ferri et Quiniae Citras(U. S. P., Br.) — citrate of iron and quinine — contains citric acid, ferric hydrate, and quinine citrate. It is prepared by adding quinine and a little citric acid to a solution of ferric citrate, and evaporating. It forms trans- parent scales of a greenish tint, slowly soluble in cold water, but freely in hot water, forming bitter, slightly styptic solutions. 509. Ferri et Strychniae Citras closely resembles the citrate of iron and ammonia in appearance, but has a bitter taste, and gives a white precipitate with ammonium hydroxide. It is prepared by adding a solution of strychnine citrate to a solution of citrate of iron and ammonium, evaporating on a water bath to a syrup, and drying on glass. 510. Ferri Phosphas (U. S. P., Br.), (FejCPOi)^).— Phos- phate of iron occurs as the result of a double decomposition between ferric sulphate and sodium phosphate. It forms a bright, slate-colored powder, insoluble in water, but soluble in acids. 511. Ferri Pyrophosphas (U. S. P.), (FeiCP^Os).— Pyro- phosphate of iron is formed by adding a solution of sodium pyro- phosphate to a solution of ferric salt. It does not crystallize, but forms scales upon evaporating its solution. These are thin, apple- green in color, turn dark on exposure to the air, and are soluble in water, but not in alcohol. Ammonium hydroxide produces no precipitate in its solution, but sodium hydroxide does. The officinal salt contains 48 per cent, of anhydrous ferric pyro- phosphate. NICKEL. 512. Occurrence, Preparation, and Properties. — This metal is found native in meteorites. Its most common ores are Niccolite (NijAsj) and Nickel Glance (NiAsjNizS). These ores of nickel, however, usually also contain cobalt, and the cobalt- ous ores are also commonly nickel bearing. The separation of nickel from its ores is a very complicated process, and for an account of it, the reader is referred to works on metallurgy. Nickel may be prepared chemically pure by igniting its oxalate or carbonate in a stream of hydrogen. This metal is silver white, tenacious, and very lustrous. Sp. gr. 9.1. It is attracted COBALT. 293 by the magnet. It does not alter in the air, but dissolves in the mineral acids, especially nitric. 513. Compounds. — The following are the most common of the nickel compounds ; they are mostly ous compounds, having the general form NiRj, and all possess a green color ; nickelous hydroxide (NiCOH)^), nickelous chloride (NiCl^-CeHjO), nickelous cyanide (Ni(CN)2"), nickelous sulphate (NiSOi- .7H2O), and nickelous sulphide (NiS). Nickelic oxide (NijOj) and hydroxide (Ni2(OH)6) exist, and are similar to the corresponding cobalt compounds. Nickel is used largely in certain alloys and for electro-plating. COBALT. Co — 59. 514. Occurrence, Preparation, Properties, etc. — Smaltite (CoAsj) and cobaltite (CoAsj.CoSj) are the most commonly occurring native ores of cobalt. It is prepared in the same manner as nickel. It is a reddish-white metal, tena- cious, and fusible with great difficulty; sp. gr. 8.9. Its other properties are very similar to those of nickel. 515. Cobalt Compounds are also chiefly ous, correspond- ing to the general form C0R2. Those containing water have a reddish color; the anhydrous compounds are blue. The cobaltous compounds are, cobaltous chloride (C0CI2), cobaltous hydrate (Co(HO)2), cobaltous sulphate (C0S04.7H2O), cobaltous nitrate (Co(No3)2.6H20), and cobaltous sulphide (CoS). The cobaltic compounds are, cobaltic oxide (C02O3) and cobaltous -cobaltic oxide Co304=Co20|j.CoO). The latter corresponds to magnetite (FejOi). 294 MEDICAL CHEMISTRY. GROUP VIII.— THE PLATINUM METALS. Platinum, Pt = 197. Ruthenium, Ru = 103. Palladium, Pd = 106. Iridium, Ir == 193. Rhodium, Rh = 104. Osmium, Os =: 105. 516. These five elements are usually' classed as "metals of the platinum ores," or the platinum group of metals. The platinum ore, or crude alloy, occurs in small metallic grains in sands of a few regions, chiefly in the Ural Mountains, Brazil, and Ceylon. These metals all form hydroxides (or salts representing them) having acid properties, and therefore play both the posi- tive and negative role. Platinum is the only one used to any extent in the metallic condition. PLATINUM. Ft = 197. 517. Occurrence, Properties, etc. — It exists in nature associated with the other members of the group ; also, in ores containing gold, lead, silver, and iron. It is a lustrous, white metal; sp. gr. 21.5. It is very tena- cious, malleable, ductile, and is capable of being drawn out into very fine wire. At high temperatures it softens without melting ; it fuses at about 1770° C. (3218° F.). Upon heating the double chloride of platinum and ammonium, it decomposes, leaving a grayish-black, spongy mass called platinum sponge. This latter has the property of absorbing great quantities of certain gases. A jet of hydrogen projected upon it readily inflames by the condensation and oxidation of the hydrogen in the. pores of the sponge, the heat developed being sufficient to ignite the hydrogen. Platinum is not affected by the air or oxygen. It unites with chlorine, arsenic, silicon, sulphur, and phosphorus. It does not dissolve in the single acids, and is only soluble in liquids generating free chlorine, as aqua regia. With many heavy metals it forms easily fusible alloys. Therefore, easily reducible metallic oxides, as of arsenic, lead, etc., ought never to be ignited in platinum vessels. Platinum is valuable for its high fusing point and its power to withstand oxidation. It is expensive, because of its scarcity. 518. Platinum Compounds. — These are of two series, platinous, PtR2, and platinic, PtR^. In the first, the metal is more basic, and in the latter, more negative in nature. OSMIUM. 295 Platinum Tetrachloride (PtCli) is obtained by dissolving platinum in aqua regia and evaporating off the nitric acid. On evaporating, it crystallizes in soluble, reddish-yellow needles. With ammonium or potassium chloride, and the alkaloids, it forms characteristic double chlorides. It is largely used as a reagent to precipitate potassium, ammonium, or the alkaloids, for quantitative estimation. OSMIUM. Os =- 193. 519. This rare metal, occurring with some of the other plati- num metals, is mentioned here for the sake of its oxide (OsOi), which has received considerable attention as a staining agent. The metal resembles platinum. The tetroxide (OsOJ (so-called osmic acid) may be pre- pared by glowing the metal in air, or by the action of chlorine and moisture upon osmium. The oxide has a very irritating, piercing odor, and is intensely poisonous. It has been used to arrest the motions or to kill the organisms in water for micro- scopical examination. Many kinds of organic substances reduce this oxide and pre- cipitate the metal, and it is due to this property that it has found use as a staining agent in histology, to bring out delicate struc- tures. PART IV. ORGANIC CHEMISTRY. 520. Carbon and Hydrogen. — The substances derived from the animal and vegetable kingdoms are composed principally of four elements: carbon, hydrogen, oxygen, and nitrogen, with occasionally sulphur and phosphorus. Few as are the chemical elements concerned, the number of the compounds of these ele- ments is almost endless. Formerly only those substances directly or indirectly derived from bodies possessing vegetable or animal life were considered as organic ; but as our knowledge increased, a large number of compounds were prepared in the laboratory from these bodies, which were identical with others prepared by plants and animals themselves. It was thus demonstrated that by pure chemical agencies many of the products of living organ- isms could be prepared, and that a vital principle was not neces- sary to form these "compounds; and, also, that by the same chemical action a great many compounds could be formed which could not be found in either animal or vegetable organisms. This greatly enlarged the field of investigation, and a new mean- ing was attached to the term organic chemistry ; it was found necessary to extend the science to include all bodies in any way resembling organic compounds, either in composition or proper- ties ; i. e., all compounds containing carbon and hydrogen. Carbon and hydrogen are the indispensable elements to the formation of organic bodies ; without these we can have no substance capable of vegetable or animal life. In the great majority of organic compounds we also have oxygen or nitrogen, or both. 521. Organic Chemistry may be defined as that branch of the science of chemistry which treats of the carbon compounds containing hydrogen, either alone, or with oxygen, nitrogen, sulphur, phosphorus, etc. While inorganic compounds, as a rule, contain but a few atoms, organic compounds frequently contain a large number; and the diversity in organic chemistry is obtained, not alone by 296 ORGANIC CHEMISTRY. 297 varying the kind of atoms, but by varying the arrangement of a few kinds. There exist, however, certain organized bodies which possess a structure entirely different from that of any known inorganic body or artificial organic substance. These organized structures are the sole product of vital action, and cannot be produced in the laboratory. Such bodies are seen in the cell of living organisms; and although we may be able at some time to construct molecules identical with those composing them, we shall never be able to impart that function of growth, reproduc- tion, and other vital processes which we call life. The com- plexity of organic compounds may readily be attributed to the inherent properties of carbon, the leading or most characteristic element of which they are composed. The atoms of carbon exhibit, in a remarkable degree, a tendency to combine them- selves into groups or chains, around which the other atoms or groups of atoms are arranged. 522. Qualitative Examination of Organic Bodies. — Organic bodies may usually be distinguished from inorganic by their behavior when heated. Organic bodies are either volatil- ized when moderately heated, or decompose into certain volatile products, leaving a black char behind them. When strongly heated in the air they take fire and burn. Those which distil unchanged deposit carbon when their vapor is conducted through a red-hot tube. Carbon. — The best proof of the presence of carbon in the organic substance is given by burning it in an atmosphere of oxygen, or by heating it dry with CuO, and collecting the COj evolved. The presence of CO^ may be shown by passing the gas from the combustion through a solution of lime water. The quantitative estimation of carbon is conducted on the same principles, but the CO2 is absorbed by a solution of potassium hydroxide contained in a U-tube, and weighed before and after the experiment. The difference in these weights gives the weight of CO2, from which the carbon may be calculated. This operation is conducted in a specially constructed furnace. The substance to be analyzed is mixed with the oxide of copper, in a hard glass tube, which is then heated in the furnace. Nitrogen may be tested for by burning the substance in the air, when, if nitrogen be present in more than traces, it will give off an odor of burning feathers or horn. Some organic substances containing nitrogen, on being heated, explode. Another meihod of testing for nitrogen is to heat the substance with potassium hydroxide and lime in powder, when ammonia is evolved. This 26 298 MEDICAL CHEMISTRY. may be detected by its odor, its reaction with moistened litmus paper, or fuming HCl. Sulphur may be detected in many cases by heating the sub- stance with a strong solution of potassium hydroxide, adding a solution of lead oxide, which is turned black on burning if sulphur be present. Another method of testing for sulphur: Solids are fused with two parts of potassium hydroxide and one of potassium nitrate. After collecting, the mass is dissolved in water, HCl added, and sulphates tested for by BaClj. Liquids are treated with fuming HNO,, or a mixture of HNO3 and KCIO3 with gentle application of heat. The solution may now be tested for sulphates as above. The halogens may be detected by heating the substance with lime, afterward dissolving in water, acidifying with HNO3, and adding a solution of Hg2(N03)2. The halogens are precipitated either as HgjClz, HgjBr,, or Hgjij. Phosphorus may be detected by fusing the substance with KNO3 plus KOH, dissolving in water, and testing for phos- phoric acid. THE DETERMINATION OF THE MOLECULAR WEIGHT OF ORGANIC SUBSTANCES. 523. The vapor density of volatile organic compounds affords an easy and certain means of determining their molecular weights. By Article 91, we have seen that the molecular weight of any body is twice its density in the gaseous state, or the density of a gas or vapor is half its molecular weight. The easiest way of determining the vapor density of a substance is that known as Victor Meyers' (represented by Fig. 55). The apparatus consists of an outer tube of glass, the bulb of which contains water or other fluid, which has a constant and known boiling point. The inner tube contains air, is stoppered at the upper end, and is provided with a delivery tube to allow the escape of the air, as it is heated by the vapor of the boiling fluid in the outer tube. The open end of this tube is placed in a cup, under water, while the water is being boiled. As soon as the air ceases to escape from the delivery tube, the cork is removed from the top of the inner tube, and a small vial containing a weighed amount of the liquid to be examined is dropped in and the cork quickly inserted. The heat boils the liquid, forces out the stopper in the vial, and the vapor thus produced drives out an equal volume of air through the delivery tube. MOLECULAR WEIGHT OF ORGANIC SUBSTANCES. 299 Fig. 55- This air is collected in a graduated tube, previously placed over the open end of the delivery tube, and carefully measured. The volume of air obtained, represents the volume of the vapor at the temperature of boil- ing water, or of the liquid used in the outer tube. The true volume under standard conditions is now to be calculated by the formula given in Art. 15. Practically, this correction is usually made by reference to tables prepared for the purpose. The volume of the vapor of a liquid of known weight having been determined, we may easily calculate the density. For ex- ample, suppose o. i gm. of alcohol be taken, and we find 48.5 c.c. of air after making the necessary cor- rections. Now, 0.1 gm. of hydro- gen measures 1116 c.c. at 0° C. and 760 mm. pressure. We now compare these volumes and we have ^ = 23, or the hydrogen occupies 23 times the volume of an equal weight of alcohol vapor. Or, one meter of hydrogen under standard condition weighs 0.896 gm., a crith. One c.c. of hydro- gen then weighs .0000896 gm. ; 48.5 c.c. of hydrogen will weigh .0043956 gm. By dividing the weight of the alcohol taken, o.i gm., by the weight of 48.5 c.c. of hydrogen, we obtain 23 as the density of the alcohol vapor. As the density of the alcohol vapor is thus seen to be 23, its mole- cular weight must be 46. We may determine the molecular weight of substances that will not wholly volatilize without decomposing, by the method of Raoult. This method consists in determining the amount of lowering of the freezing point of a solvent, due to the substance dissolved in it. The lowering of the freezing point Victor Meyers' Apparatus. 300 MEDICAL CHEMISTRY. is proportional to the quantity of the solid in solution. While this law is not perfectly uniform for inorganic substances, it is uniformly so with organic substances, with very few excep- tions. Let I gram of a compound be dissolved in loo grams of a liquid with which it forms no chemical union. Let the molecular weight of this compound be represented by M. If we now cause the solution to freeze, we shall observe that it freezes at a lower temperature than the solvent. This depression of the freezing point we will represent by D. If we multiply this depression by M, the molecular weight of the compound, we shall have the depression for M grams of the substance, /. e., the molecular weight expressed in grams. Let this be repre- sented by T. Then we shall have D X M = T. Raoult found that the value of T is very nearly constant for the same solvent. The value of T for water is 19, for acetic acid 39, for benzene 49. Now, as D is determined by experiment, and T is constant, M may be easily calculated by dividing T by D, or M = ^, For example, a solution of glucose containing 10 grams to loo grams of water was placed in a beaker of 400 c.c. capacity, and provided with a three-holed cork, one hole for the thermometer and one for the stirring rod. It was cooled to — 2° C. A crystal of ice from a similar solution was dropped in to make it freeze. The thermometer rose to — 1.06° C. The depression due to i gram was then one-tenth of this, or 0.106° C. Hence, 19 -i- 0.106= 179 as the molecular weight of glucose. Analysis gives us the empirical formula CHjO = 30. By multiplying this number by 6 the result is 180, which is near enough to determine that as its formula, instead of any other multiple of 30. The slight difference here is within the limits of experimental error. 524. To deduce the formula from analysis, — rule: Divide the percentage of each element by its atomic weight and express the ratio of these quotients in their lowest terms. Analysis of Alcohol. C = 52.16. O = 34.80. H= 13.04. 52.16 -=- 12 = 4.34 atoms of carbon. 34.80 -J- 16 = 2.17 atoms of oxygen. 13.04 -j- I ^ 13.04 atoms of hydrogen. Ratios, C 4.34, O 2.17, H 13.07. Lowest terms, C 2, O i, H 6. CONSTITUTION OF ORGANIC COMPOUNDS. 30 1 As per cent, is equivalent to parts in one hundred, we may calculate the amount of carbon in each molecule by the follow- ing proportion : 100: 46:: 52.16: 23.99, or in 46 parts alcohol there are approximately 24 parts of carbon. For oxygen we have 100 : 46 :: 34.80 : x ^ 16.008. For h)«irogen we have 100 : 46 : : 13.04 : x = 5.998. The atomic weight of carbon is known to be 12, or each molecule contains 2 atoms of carbon. As the atomic weight of oxygen is 16, each molecule contains one atom of oxygen. As the atomic weight of hydrogen is i, each molecule of alcohol contains 6 atoms of hydrogen. The molecular formula of alcohol is CjHeO, making the molecu- lar weight 46. The vapor density of alcohol we found above to be 23, its molecular weight, therefore, is 46. THE DETERMINATION OF CONSTITUTION OF ORGANIC COMPOUNDS. 525. This is permissible only when we know the behavior of the compound with reagents. This may be illustrated as follows : When we treat an ethereal solution of CH3I with sodium we should set free the methyl. CH3I + Na = CH3 + Nal. This CH3 must have one free bond of attraction, thus : I H— C— H H The vapor density of this gas is 15. The molecular weight, therefore, is 30, or corresponds to CjHs; i. e., the two methyl C=H3 radicals unite by their free bonds and we have | C=H3 By treating CjHs with chlorine we form CjHjCl. This treated with KOH gives C2H5OH, or ethyl alcohol. As OH has taken the place of CI in CjHgCl, we conclude that the OH has gone in as hydroxyl. This atom of hydrogen can be replaced with sodium or potassium, but none of the others in the mole- cule. This atom, therefore, has a different position in the molecule from the others. The relation of the carbon atoms is 302 MEDICAL CHEMISTRY. not destroyed by the above reaction, and therefore we arrive at the conclusion that the formula is | . Again, we have the ^— OH. reactions, CjHgO + HCl = CjH^Cl + H^O. t. e., we have CjHj and OH groups in alcohol. And again, if we treat CjHjCl with nascent hydrogen we obtain CjHj and HCl. CjHj we have seen above to be di-methyl, or | CEEH3 In methyl ether, which is isomeric with alcohol, no one of the hydrogen atoms can be replaced with sodium or potassium ; and when we remove the oxygen atom with HIj the connection of the carbon atoms is broken, with formation of compounds having one carbon atom only. Thus : QHeO + HI = CH4O + CH3I, or C^HgO + 2HI = 2CH3I + HjO. This shows that the oxygen atom in methyl ether acts as a link between the two carbon atoms, as its removal breaks the mole- cule apart. Also, that the hydrogen atoms are all alike in the molecule. Hence, the formula would be represented as follows: CSH3 \ O . In alcohol the formula would be represented as fol- C=H3 lows: CH3 — CH2OH. In the same way we determine that the CSH3 rational formula of acetic acid is I =0 C— OH. It is the aim of chemists to follow out such reactions for all organic bodies, to determine the rational formula. This has been done in most organic substances. When we know the structure of the molecule of the substance we are able in many cases to construct it synthetically. Thus, if we compare the following formulae we see a close resemblance : — CONSTITUTION OF ORGANIC COMPOUNDS. H H H C = C C / \ C CH V HC CH \-cLo- -H 1 II HC C — — I H c — c = o \ O — H 3°3 H If we treat the first of these substances with sodium, we obtain CgHsONa. If we treat this at a high temperature with CO2, this gas enters the molecule, CO going in with the NaO group to give CeHsCOONa. The other O goes to the neighboring carbon atom and gives OH. Thus salicylic acid is prepared from carbolic. The atoms of carbon exhibit, in a remarkable degree, a ten- dency to combine themselves into groups or chains, around which the other atoms or groups of atoms are arranged- In other words, the carbon atoms are the skeleton in and upon which a very complex structure may be built. The underlying principle of organic chemistry is the grouping of the carbon atoms, and upon these groups the whole superstructure is based. 526. Hydrocarbons. — Carbon Nuclei. — Carbon is a tetrad and can combine with four monads. As has been said, .it can also unite with another carbon atom, and the two atoms thus united will H\ /H combine with six monad or hydrogen atoms : H — C— C — H H/ \H Three, four, five, or any number (n) atoms of carbon may thus unite, theoretically at least, and give rise to a chain of atoms, which has been called an open chain. Again, the same atoms may combine as follows : giving rise to closed chains. By a little consideration it will be seen that, in either of the first two formulae given above, if we increase the carbon atoms c c / \ =c c= // \ -c c 1 1 =c c= or 1 II -c c- \ / c 1^ / c II 1 304 MEDICAL CHEMISTRY. in any given formula, we also increase the number of bonds, or points of contact for hydrogen atoms, by two for every carbon H H H H H H H atom added. Thus : H— C- C— C— H + CH, = H— C— C— C— C-H ; III I I I I H H H H H H H HHHH HHHHH H-C— C— C— C— H + CH„ = H— i— C— C— C— C— H ; I I I I I I I I I HHHH HHHHH and so on. We thus have a series of hydrocarbons differing from each other by the constant quantity of CHj. Such a series is called a homologous series. In the same chain of carbon atoms we might have the following arrangement of the bonds of H H I I attraction :— H— C— C = C + CH, = I I I H H H HHHH HHHHH H-C— C = C— C— H + CH. = H— C— C = (Lc— C— H. I II II H H H H H This gives rise to another homologous series, each member differing from the corresponding member of the series above mentioned by the constant quantity of Hj, and known as the isologous series. In the vertical columns of the following table we have the homologous series ; in reading from left to right, we have the isologous series of hydrocarbons. C* C,H, CjHj CjHj CjHg C^Hj CjHj CjHj C^Hjj CjHjj This table does not by any means represent all the possible * Unknown. CHj CH^* C2He C,H, C,H3 C,He C^Hjj C4H8 ^6^12 C5H10 C,iiu C6'^12 C7H,, C,H,, CsHig CnH2n + 2 CnHjn CONSTITUTION OF ORGANIC COMPOUNDS. 305 compounds, but gives an idea of how all known hydrocarbons may be classified by extending the table. The members of these series having few carbon atoms in their molecules are termed the lower members, and those having a higher number of carbon atoms the higher members. 527. Isomerism, Polymerism.— Besides the method of grouping the carbon nuclei which we have indicated, a variety of other methods may be conceived, some of which really exist. Thus the group containing four carbon atoms may be arranged as HHHH HHHH I I I I I I I I follows: — H— C— C— C-C— H, H— C— C=C— C— H, I I I I I I H H H II H H H H H H H III II H— C— C— C— H, H— C C— H 1 I I H I H H— C— H H— C C— H H H H The first and third of these would have the same number of atoms and the same formula, C4H10, but would have different physical and chemical properties. Compounds having the same chemical composition, but possessing different properties, are termed isomeric bodies. The same may be said of the second and fourth of the above formulae ; the empirical formula is CJig, but they are quite different in the constitution of their molecules, while they are the same in composition. These two compounds are isomeric. The chemical and physical properties of organic compounds depend not only upon the kind and number of atoms, which is designated the composition of the molecule, but also upon the arrangement of the atoms in the molecule, or the constitution. It is in this way that we may have several compounds, each answering to the same formula, and giving the same result on analysis, but totally different in properties. We may mention here as examples, ammonium cyanate, NH^OCN, and urea, CO < ts-tt Also, fCjH, rCH, fCHj N-^ H N-^CjHj nJcHj (h (11 (CH, Propylamin- Methyl-ethylamin. Trimethylamin. 3o6 MEDICAL CHEMISTRY. In those members of the above series of hydrocarbons having four or more carbon atoms, we may have several isomeres. The number of these isomeres increases rapidly with the increase of carbon atoms. Thus, there are two possible butanes, known as butane and iso-butane or methyl-propane. H H H H H H H I I I I III H— C— C— C— C- H H— C— C— C— H I I I I I [ I H H H H H I H H— C— H I H Butane. Methyl-propane or Iso-butane. As we ascend in the series we find for C5H12 three isomeres, for CeHii five, for C10H22 seventy-five, and for C11H24 it has been computed that we may have no less than one hundred and fifty-nine isomeres. This fact explains why we can have an in- definite number of compounds classified in the above table. This same law of isomeres applies to the other homologous series as well as to the first. Polymeric bodies are compounds having the same percent- age composition but different molecular weights. We have a striking example of this property in the second column of the table above. Ethene, C2H4, Butene, CjHj, and Octene, CgHij, are polymeric bodies. Starch, cellulose, dextrin, and glycogen are polymeric bodies. Note.— ^Metamerism is sometimes used as synonymous with isomerism. 528. Nomenclature of Organic Compounds. — The no- menclature of organic compounds is complicated and unsatisfac- tory. The large number of compounds to be considered and their endless derivatives make it next to impossible to devise a system of naming them that shall meet with general approval. The result of the rapid advance in the discovery of organic com- pounds has been to produce confusion. Certain compounds have received different names by different observers, and it is no unusual thing to meet with four or five synonymous names for the same compound. In consequence of this, the whole subject of the nomenclature is being revised by an International Commission, appointed by an International Congress of Chemists, whicb met at Paris in 1889. ORGANIC RADICALS. 307 The Commission has published a preliminary report embracing sixty-two rules for naming organic compounds, as the result of its deliberations. These rules are as yet not generally adopted. It may be stated, however, that the nomenclature of organic compounds is in the transitional stage. We shall endeavor to follow the best usage in the naming of chemical compounds. 529. Organic Radicals. — In organic chemistry, as in inor- ganic, although to a greater extent, we are constantly dealing with certain well-defined groups of atoms, which retain their identity through a large series of compounds and behave in chemical reactions like simple radicals or atoms. It is evident that by removing one or more atoms of hydrogen from any saturated hydrocarbon, the remaining group of atoms may act as a compound radical ; while the unsaturated hydro- carbons of the acetylene or olefine series may act as radicals without the removal of any hydrogen atoms. These hydrocarbon radicals are usually designated by the ter- mination yl. Thus : CH3 is known as methyl ; C2H5, as ethyl ; CeHj, as phenyl. These radicals are called, collectively, hydro- carbon or alcohol radicals, and the quality of their combining power is electro-positive. The following radicals are frequently met with, and may be committed to memory by the student with advantage : — Hydroxy] (OH), . Carbonyl (CO), . Carboxyl (COOH), . Cyanogen (CN), . . Nitroxyl (NO^), . . Sulphonyl (.SO,OH), Amidogen (NHj), • Methyl (CH3), . Ethyl (CjH^), . AmyUC^Hi,), . . . Phenyl (C5H5), . . Acetyl (CjHiO), Benzoyl (CjiljO), . occurring in alcohols. " " ketones. organic acids. cyanides. nitro-compounds. sulphonic acids. ainids. wood alcohol. alcohol. fusel oil. carbolic acid. acetic acid. benzoic acid. All organic bodies can be classified in one or other of the following groups: hydrocarbons, alcohols, ethers, aldehydes, acids, ketones, halogen compounds, ethereal salts, amins, amids, nitrils, cyanogen compounds, quinons, organo-metallic com- pounds, carbohydrates, proteids, alkaloids, glucosides. The first and simplest class of organic compounds we shall meet are the hydrocarbons. 3o8 MEDICAL CHEMISTRY. 530. Nomenclature of Homologous Hydrocarbons. — The following are the names proposed for these hydrocarbons : — ist Series. 2d Series. 3ii Series. 4lh Series. PARAFFINES. OLEFINES. ACETYLENES. Methane, t-'nrljn Methene CnrlgD — 2 Carbon C°H2„_, CH,. (unknown) CH,. C Ethane, Ethene, Ethine C,H,. C,H,. (Acetylene), Propane, C3H,. Butane, Propene, Butene, Propine, C,H,. Butine, Propone, C3H2. Butone, Quartune, or Butune, Q^io- C,H,. C,H,. C,H,. C4H,. Pentane, Pentene, Pentine, Pentone, Pen tune, ^5^12- Q^io- CsHs- CjHe. C5H4. Hexane, Hexene, Hexine, Hexone, Hexune, CeH^. ^6^12. CjHi„. CeH,. CeHe. Here, as above stated, there is not perfect uniformity in nomenclature, and, where they conflict, we shall follow the best usage in preference to strict conformity to the above. 531. The Paraffins. — The paraffins are chemically indifferent bodies, because they are fully saturated compounds. They are stable compounds, not easily attacked by reagents. They are not acted upon by alkalies or acids. Many of these hydrocar- bons are found in petroleum and the gases accompanying it, and others are found in the products of the dry distillation of coal and other organic substances. They may also be prepared by one of the following reactions: — 1. By treating an alkyl iodide with zinc at 160° C. in presence of water. OH 2. By heating certain salts of acids containing more carbon. Thus, by heating calcium acetate with sodium hydroxid. (C2H302)2Ca + 2NaOH = 2CH4 + NsjCOs + CaCOj. 3. By electrolysis of acids of the acetic acid series. The lower paraffins are gaseous and insoluble in water. Those below butane are gases at ordinary temperatures, those between QHio and CigHji are liquid, and the higher members are solids. Alcohol dissolves the gases slightly, the liquids readily, and the C2H5I + HOH + Zn = C2H5 + Zn I j METHANE — ETHANE. 309 solids with difficulty. The boiling point, melting point, and specific gravity increase with the increase of carbon atoms. 532. Methane, or Marsh Gas,CH4. — This gas is a constant product of the decomposition of vegetable matter under water, and may frequently be seen rising to the surface of stagnant pools. It is produced by the dry distillation of coal, and is therefore a con- stituent of ordinary illuminating gas. It is the chief constituent of miners' " fire damp." It occurs in the gases of the intestines to the extent of from 25 to 50 per cent. Natural gas is composed of from 90 to 95 per cent, of marsh gas, with small quantities of nitrogen and carbon dioxid. Preparation. — Methane may be prepared by heating a mix- ture of 4 parts of sodium acetate, 4 parts of sodium hydroxide, and 6 parts of lime. It may be prepared synthetically by the electric arc in an atmosphere of hydrogen, which produces ethine (acetylene). Ethine, when mixed with hydrogen and passed through a tube containing spongy platinum, forms methane, C2H6. Ethane passed through a heated tube gives the following reaction : — 2CjH, = 2CH4 + Cj + 2Hj. When a series of electric sparks are passed through a mixture of hydrogen and carbon oxide, CH4 is prepared. CO + 3H2 = CPIj + Hfi. By these reactions the elements are made to yield CH, and CzHj, which can serve as the starting point in the synthesis of other organic compounds, and thus bridge over the gap between inorganic and organic compounds. Properties. — Methane is a light, colorless, transparent, odorless, tasteless, combustible gas. Density = 8. Sp. gr. = 0.559. Under 140 atmospheres of pressure at 0° C. (32° F.), it condenses to a transparent liquid. It burns in the air with a bluish flame, giving no light but a high temperature. Mixed with air or oxygen, it forms an explosive mixture (" fire damp"). By passing the gas through a red hot tube it is con- verted into carbon and hydrogen, with traces of QH2, CzH^, CjHs, and QoHg. Mixed with CI and diluted with CO2 it forms chlorine substitution compounds, CH3CI, CHjCl,, CHCI3, and CCI4. It is irrespirable, but not poisonous. Poisoning by house gas containing CH^ is produced by the other gases which it contains.' 533. Ethane, or di-methyl (CH3 — CHg) occurs in crude petroleum, and is a constituent of some of the natural gas wells of western Pennsylvania. The oil wells discharge large volumes of 3IO MEDICAL CHEMISTRY. gas containing H, CHj, and CjHe, which are used for heating and lighting in the neighboring districts. When crude petroleum is heated, the hydrocarbons, ethane, propane, and butane are evolved as gases. These are collected and subjected to conden- sation, yielding a liquid known as cymogene, used in freezing machines and consisting chiefly of butane (C4H10). Properties. — Ethane is a gas at ordinary temperatures, but is condensed to a liquid under a pressure of 46 atmospheres at 4° C. It burns with a faintly luminous flame. It is slightly soluble in water and alcohol. 534. Propane (CsHb) is present in crude petroleum and is liquid below — 30° C. It may be prepared artificially by the action of hydriodic acid (HI) upon glycerin at 275° C. 535. Butane (CjHio) boils at 1° C. Its sp. gr. is 0.6, being the lightest liquid known. It is found in crude petroleum. This is the first paraffin in which we have an isomer, isobutane, con- taining one side chain. H HoC — C — — CHq. H3 This compound boils at — 17° C. 536. The normal paraffins are regularly formed compounds, in which each C atom is linked to two other C atoms. In the isoparaHins one carbon atom is linked to three others, as in butane above. In the neoparaffins two carbon atoms are each linked to three others. H H H,C — C — C — CH, /I CH3 CHg That is, in the iso-compounds we have one side chain ; in the neo-compounds we have two side chains. In the mesoparaffins one carbon atom is linked to four others. CH3 H,C — C — CH, I CH, I CH, PETROLEUM. 3" PETROLEUM. 537. The higher members of this series are found in American petroleum, and may be isolated to a great extent by careful frac- tional distillation. The distillation of petroleum is carried on on a large scale in certain parts of this country, and a variety of products are found in the market, the names of which do not have any reference to the chemical composition. The following are a few of the most important of these products, with their boiling points and uses : — Name. Boiling Point. Principal Use in Arts. Cymogene 0° C. ( 32° F.) 18.3° C. ( 65° F.) Used in ice machines. Rbigolene . Used to produce cold by evap- oration and as an anaes- thetic. Petroleum Ether . . 40° to 70° C. (104° As a solvent and for making to 158° F.) " air gas." Gasolene . . . 48.8° C. (119° F.) For making "air gas." C Naphtha 82.2° C. (180° F.)) f As a solvent for fats and rubber, B Naphtha . . 104.4° C. (220° F.) \ ■ 1 hence for cleaning cloths. A Naphtha .... 148.8° C. (300° F.) J ( So.called" safety-oil." Benzine (deodorized) 120° to 150° C. 248° to 302° F.) For varnishes and paints. Kerosene, or Refined Petroleum .... 176° C.(349°F.) For ordinary lamps. Mineral Sperm Oil . . 218° C. (424° F.) Lubricating Oil . . . 301° C. (S74°F.) Lubricating machinery. Paraffine Solid. For candles. The vapors of all the lighter products when combined with air form explosive mixtures, and hence, laws exist in most countries prescribing the lowest temperature at which kerosene shall give an inflammable vapor, or at which it shall "flash." The law of the State of New York declares that oils used for illuminating purposes shall not give a vapor that will "flash" below 100° F., and shall not themselves ignite below a temper- ature of 300°. Fossil resins, bitumen, ozocerite (animal wax), all belong to this group of hydrocarbons. 538. The defines, or C^Hj^ Series. — The olefines differ from the paraffins in being unsaturated compounds. The first member of the series, ethene or ethylene (CjH^), combines directly with chlorine, forming a thick, oily fluid, from which the dis- coverers named it olefiant gas. The iodide and bromide may also be formed by direct union. The olefines combine with the hy- 312 MEDICAL CHEMISTRY. dracids, HCl, HBr, HI, and also with fuming HjSOi, and with HNO3. qHj + HCl = C^HjCl. Most defines are soluble in alcohol and ether, but most are insoluble in water. They are soluble in strong H2SO4. Ethene is found in illuminating gas, the illuminating power of which depends largely upon its presence. It is a colorless gas of a peculiar, pungent odor and may be separated from the other constituents by its solubility in H^SO, with which it combines. It burns in the air with a bright luminous flame. Its sp. gr. is .9785 ; density 14. The higher members of this group are unimportant. The following are the chief members of the series : %i. Ethene (QHJ gas. Heptene (C,H„) boils at 100° C. Propane (C3H5) gas. Octene (CjHjg) " " 125° C. Butene (QHg) gas. Nonene (CgH,j) " " 153° C. Tropene (C5H11,) boils at 35° C. Decene (CioH,,,) " "200=0. Hexene (CjHjj) " " 70° C. 539. Third Series. — Ethine, or Acetylene (C2H2). This series of hydrocarbons falls short of saturation by four monad atoms and can, therefore, act as bivalent and tetrivalent radicals. The first member of the series, ethine (CjHj), is the only hydro- carbon which can be formed by the direct union of its eieme;its. It is produced when carbon is strongly heated in an atmosphere of hydrogen ; that is, by passing a powerful electric current between carbon poles in a globe filled with hydrogen. Ethine, or acetylene, comljines directly with either two or four atoms of chlorine, bromine or iodine. Nascent hydro- gen converts it into ethene, and oxidizing agents (potassium permanganate, etc.), into oxalic acid. Ethine is formed when- ever kerosene or coal gas is incompletely burned, and gives the disagreeable odor detected in a room when the lamp is turned low. It is found in coal gas and possesses a high illuminating power. This hydrocarbon is remarkable in the fact that its hydrogen is easily displaced by metals ; thus, by heating sodium with C2H2 we obtain CjHNa (mono-sodium acetylid) and CjNaj (di-sodium acetylid). When passed into a solution of silver nitrate it forms a white precipitate of silver acetylid (C2Hg2H20), an explosive compound. 540. Fourth Series. — General Formula, CJcl^^—i. This series of hydrocarbons includes turpentine and a large number of other so-called essential, or volatile oils. These oils are mostly TURPENTINE. 313 isomers or polymers, having the formula CioH,e, or a multiple of this. 541 . Turpentine is extracted from several varieties of the con- ifera family, notably the pine. When turpentine is distilled, the hydrocarbons volatilize, while resin remains behind. Oil of tur- pentine is a mobile, colorless liquid, with a sp. gr. of 0.89, and boils at 160° C. (320° F.). It is almost insoluble in water, but dissolves in alcohol, ether and glacial acetic acid. It dissolves sulphur, resin and phosphorus. It absorbs oxygen from the air and becomes oxidized, forming a resinous body. The absorbed oxygen is converted into ozone, and this exjjlains its oxidizing, disinfectant and antiseptic action. As the oxidation of turpentine takes place more rapidly when mixed with lead oxide, this oxide is often intermixed with the turpentine in paints, to increase the rapidity of drying. It attacks lead rapidly, but not tin. A paper dipped in turpentine and introduced into a jar of chlorine gas inflames spontaneously, forming substitution pro- ducts. Iodine and bromine have a similar action upon it. It unites directly with HCl, producing several hydrochlorates. Sulphuric acid acts violently upon turpentine, and yields a number of isomeric and polymeric derivatives. After standing 24 hours the mixture separates into two layers. The upper layer, when distilled at about 250? C. (482° F.), yields a mobile liquid, which, when purified by longer contact with HjSOi and then with a solution of NaOH and re-distilled, may be separated into terebene (QoHis), colophene and several other polymers. These compounds are used in medicine. 542. Terebene has a fine thyme-like odor, and is optically inactive. In density and other respects it much resembles turpentine. It is probably a mixture of camphene with some other liquid. Terebene, when pure, is a colorless, oily, yellow liquid. It is readily soluble in ether, less so in alcohol, and almost insoluble in water. It has been used in medicine as an expectorant, in doses of from 4 to 6 minims, and as a local remedy. 543. Terpin. — On leaving turpentine in contact with the air for some time it gradually changes into terpin hydrate (QoHig- 3(H20)). This body is more easily obtained by agitating, for a day or two, a mixture of 8 parts of turpentine and 2 of nitric acid, previously diluted with alcohol. Terpin hydrate occurs as anhydrous rhombic crystals. It is easily soluble in alcohol (10 parts), slightly soluble in water (250 parts), and sparingly so in chloroform, carbon disulphide and ether. It melts at 116° C, 27 314 MEDICAL CHEMISTRY. giving off water and being converted into anhydrous terpin (CjoHiszOH). It is a crystalline body, fusing at 103° C. and subliming at about 250° C. (480° F.). It rapidly absorbs water to form terpin hydrate, which behaves like a diatomic alcohol. It is dehydrated by P2O5 and converted into terebene and colophene. It is employed in medicine as an expectorant, in doses of from two to three grains. It may be given in as large as 20- to 30-grain doses. 544. Terpinol. — By boiling together terpin and water, acidu- lated with sulphuric acid, terpinol is obtained. It may be formed from turpentine by leaving it in contact with concentrated hydrochloric acid, or by passing HCl gas through a solution of terpin in alcohol and ether. By treating the resulting terebenthin dihydrochlorate with boiling water or a solution of KOH it decomposes with the formation of terpinol. Terpinol occurs as a colorless oily liquid, with an odor resembling rosamin or hya- cinths, having a sp. gr. of .852. It is soluble in alcohol and ether, but insoluble in water. It has been employed in medicine as an expectorant, in doses of from 10 to 15 minims (600 to 900 mgrs.). 545 . Caoutchouc, or India Rubber, is the dried milky juice of several tropical trees of the Hevea species. The fresh juice is acid. It is a mixture of several hydrocarbons which are in- soluble in alcohol and water, but soluble in ether, benzene, chloroform, carbon disulphide and turpentine. When cold it is hard and tough, but on heating it becomes soft, elastic, and finally melts, and on cooling remains soft and viscid. It is much used in making elastics, water-proof fabrics, elastic tubing, etc., and is acted upon by but few reagents. The black color of the commercial article is due to smoke and partial decompo- sition. Caoutchouc combines with sulphur. Vulcanized India rub- ber is obtained by mixing it intiniately with sulphur, by the aid of carbon disulphide, to the extent of 2 or 3 per cent., and afterward heating. Common white rubber goods, as rubber tubing, etc., are also mixed with oxide of zinc and other im- purities to a very large extent, in some cases but a few per cent, of rubber being used. When mixed with about half its weight of sulphur, a hard, horny mass called vulcanite, or ebonite, is produced, which is used in the manufacture of combs, cheap jewelry, etc. When heated caoutchouc decomposes, but does not volatilize. 546. Gutta-percha is the hardened, milky juice oi Jsonandra ESSENTIAL OILS. 315 gutta, a tree growing in some parts of India. It resembles caoutchouc, but is harder and less elastic. In hot water it becomes quite soft and can be moulded into any shape, which it retains on cooling. With solvents and high temperatures it behaves like caoutchouc. 547. Volatile or Essential Oils. — Volatile oils are those ap- proximate principles to which, in the majority of cases, the odors of plants are due. They are extremely variable in com- position, but many of them belong to the terpin series of hydro- carbons. The principal characteristics of these essential oils are their odors, variations in the rapidity of oxidation, and physical properties. They are soluble in alcohol, ether, benzene, petro- leum naphtha, chloroform, carbon disulphide, paraffin and other volatile oils, and in the fixed oils. They may be classified as follows : 1. Oils consisting chiefly of terpenes(CioHi6) and their oxidized products, such as turpentine, oil of lemon, and the oils of bergamot, birch, chamomile, caraway, hops, juniper, myrtle, nutmeg, orange, parsley, pepper, savin, thyme, tolu and valerian. 2. Oils consisting chiefly of cedrenes (CisHjs) and their oxid- ized products, such as the oils of cedar, cubebs, cloves, rose- wood, calamus, cascarilla, and patchouli. 3. Oils consisting chiefly of aromatic aldehydes and allied bodies, such as the oil of almonds and oil of cinnamon. 4. Oils consisting chiefly of ethereal salts or compound ethers, such as oil of wintergreen or oil of mustard. Some of the more important oils of classes three and four are described in other places. These volatile oils, of which the hydrocarbons form the main constituent, probably originally consisted of terpenes or cedrenes only. As usually met with, they are generally mixtures of the unchanged hydrocarbons, or oleoptenes, with the solid, oxidized, camphorized bodies termed stearoptenes. We frequently, also, find more highly oxidized bodies called resins. On cooling the crude oil the stearoptenes often crystallize out. On distilling the oils the more volatile hydrocarbon first passes over, and may thus be separated from the oxidized solid portions. The more volatile portion of the distillate may be wholly freed from the oxygenized bodies by distilling with free sodium, and thus the pure hydro- carbon is obtained. The volatile oils of plants are extracted : I. By pressure, as the oil of laurel, lemon, orange, berga- mot, etc. 3l6 MEDICAL CHEMISTRY. 2. By distillation with water, or with a current of steam passed over the matter to be extracted. This is the most com- mon method. 3. By first fermenting the part of the plant to be extracted. This is applied more especially to certain seeds, as the mustard, bitter almond, etc. After the fermentation the oil formed is sepa- rated by distilling with water. 4. By solution in the fixed oils devoid of odor, such as poppy oil, oil of ben, etc. The essential oils are usually liquid at ordinary temperatures, but deposit stearoptenes or camphors at low temperatures. They have, in most cases, highly characteristic odors, and a few have boiling points which are somewhat high. They volatilize rapidly at ordmary temperatures. The essential oils are usually color- less or yellow when freshly prepared, but darken on expos- ure to air and ultimately become sticky and resinous. Some oils have a well-marked blue color. ,Most of the essential oils are optically active, but their rotatory powers are variable and frequently changing. The sp. gr. of essential oils ranges usually between .850 and .990. A few, however, have specific gravities outside these limits. The oxygenated and sulphuretted oils, as the oil of bitter almonds, wintergreen, mustard, etc., are heavier than water. The essential oils are readily combustible. They are insoluble, or nearly so, in water, the water taking up, however, the charac- teristic smell and taste of the oils. They are freely soluble in alcohol, but are mostly precipitated on dilution with water. The separation is rarely, if ever complete. The essential oils are miscible in all proportions in the fixed oils. Turpentine, petroleum naphtha, and carbon disulphide being insoluble in water, the essential oils may be separated from an aqueous liquid by agitation with these solvents. The analysis of essential oils presents great difficulties. They are liable to adulteration with alcohol, chloroform and turpentine. Alcohol in essential oils may be detected by gradually adding dry CaClj and agitating and warming the mixture in a water bath. If alcohol is present in larger proportions than mere traces, a heavy liquid layer will be formed at the bottom of the tube. Anilin red is insoluble in essential oils, if pure and free from alcohol, but in the presence of a small proportion of alcohol " the addition of anilin red colors them a deep red. Chloroform may be detected by dissolving the oil in alcohol, CAMPHORS. 317 and warming the liquid with zinc and dilute sulphuric acid. Water is added, the aqueous liquid is separated and tested for chlorides with AgNOa and HNO3. The precipitation of AgCl proves the presence of chloroform in the oil. A large number of volatile oils are employed in medicine, either in a pure state or the form of aqueous saturated solutions, called medicated waters. Solutions in alcohol, one in five, are termed essences ; one in fifty are termed spirits. CAMPHORS. 548. Common Japan Camphor, CjoHisO, is obtained in China and Japan by distilling the branches and lea.ves of Zawus camphora with water. It is a white, translucent, crystalline mass, having a powerful, peculiar, pungent odor and taste. It is readily purified by sublimation at 205" C. (401° F.). It melts at 175° C. (357° F.) and burns with a smoky flame. Camphor is very slightly soluble in water, but readily soluble in alcohol, ether, acetic acid, benzene, chloroform, carbon disul- phide, fixed and essential oils. Aqua Camphorae and Tinc- tura Camphorae are official, and it enters into the compo- sition of Linimentum Camphorae, Liniment. Saponis, Tinctura Opii Camphprata. Camphor forms a large number of decomposition products and derivatives, under the action of reagents, but we shall notice but one of these. Borneo!, or Borneo Camphor, has the formula C,oH,80. 549. Camphor Monobromide — Camphora Monobro- mata (U S. P.), CioHi5BrO, is prepared by adding bromine to a solution of camphor in chloroform, by which camphor dibromide is obtained. This compound is unstable, and on standing, sets free hydrobromic acid and forms monobromated camphor, which crystallizes in colorless, prismatic needles or scales, permanent in the air, having a mild camphoraceous odor and taste, and neutral reaction. Its solvents are essentiallythe same as those of camphor. It meltsat 65° C. (149° F.), boils at 274° C. (525° F.), and is volatilized with partial decomposition. In medicine it is used as a sedative, cardiac stimulant, etc. 550. Eucalyptol, C12H20O, is a colorless liquid, boiling at 175" C. (347° F.), and possessing an aromatic odor. It is contained in the leaves of the Eucalyptus globulus, a tree growing in Tasmania. On account of its supposed effect upon miasmatic 3l8 MEDICAL CHEMISTRY. atmospheres, it has been cultivated in southern Europe, the United States and northern Africa. By distilling it with phosphorus pentachloride, PClj, eucalyptin, CuHig (by some CioHie), is obtained. Eucalpytol is slightly soluble in water, but soluble in alcohol. The oil has feeble antiseptic properties, and has been used in bronchitis, cystitis, and in intermittent fever. 551. Menthol,* or Menthyl Alcohol, QoHjoO, is a white, solid, crystalline body occurring in oil of peppermint, and possessing a strong odor of this plant. It melts at 36° C. (96.8° F.) and boils at 210° C. (410° F.). Menthol is soluble in alcohol and the essential oils. 552. Thymol — Methyl-propyl-phenol, CoHsJ ch. - CjoHuO. Thymol is a camphor or stearoptene of oil of thyme. It is also contained in the volatile oil of horse mint. It is extracted by agitating the oil with a solution of NaOH. The aqueous layer is separated and treated with the gas of dilute acid, when the thymol separates as an oily layer. The better plan is to collect the crude oil and subject it to low temperature, when the thymol crystallizes out. It may be purified by recrystallization from alcohol. Thymol is a phenol and resembles carbolic and cresylic acids in its general properties. It is a powerful antiseptic, being ten times more effective than carbolic acid. It acts as an expectorant on the mucous membranes, but it does not irritate the skin like carbolic acid. Thymol occurs in large colorless crystals, having an aromatic odor and a burning taste. It melts at 44° C. and boils at about 230° C. It is scarcely soluble in water, requiring about 1200 parts of cold or 900 parts of boiling water for solution. Alcohol dissolves its own weight of thymol, and the greater part separates again on dilution. A solution of four grains of thymol to a fluid ounce of alcohol is miscible with water in all proportions. It is sparingly soluble in glycerin, requiring 120 parts for solution. I.t is readily soluble in ether, chloroform, petroleum spirit, and oils. When triturated with camphor, a syrupy liquid is obtained, which is readily miscible with vaseline or similar preparations. Thymol is soluble in strong acetic acid. A delicate test for thymol consists in dissolving a little of the sample in i c. c. of glacial acetic acid, and adding 5 or 6 drops of strong sulphuric, or i * Although really an alcohol, it is classed here with the camphors, owing to physical properties. RESINS, OLEO-RESINS, GUMS, BALSAMS. 319 drop of nitric acid, when, if thymol be present, it first becomes green, and then on shaking a fine blue color makes its appear- ance. Phenol gives a violent red color, but menthol, cam- phor, borneol, and salicylic acid give no color when similarly treated. 553. Cantharidin (CjoHuOj) is the active principle of cantha- rides, or Spanish fly, and of other vesicating insects. It has many of the properties of camphor. When pure it forms four-sided prisms, but frequently deposits in needles of micaceous appearance. It melts at 200° C. and sublimes in white flakes, which strongly irritate the eyes, nose, and mouth, and condense in lustrous rectangular prisms. Cantharidin has feeble acid properties. It is insoluble in water but dissolves in caustic alkalies to form can- tharidates. Cantharidin may be crystallized from hot hydro- chloric acid, but is soluble in strong sulphuric acid, being repre- cipitated on dilution. Cantharidin dissolves readily in alcohol, ether, acetic ether, and chloroform. It is nearly insoluble in naphtha and carbon disulphide. It is extracted from acidulated solutions by agitation with chloroform. Cantharidin has well marked poisonous properties, and the beetles containing it have been administered with criminal intent. In toxicological in- quiries the contents of the stomach and intestines should be carefully examined for the iridescent green wing-cases of the beetle. If the tincture has been taken the only available test is the isolation of the cantharidin with chloroform, and the appli- cation of the residue to a sensitive part of the skin. The mix- ture of one part of cantharidin in 500 of lard produces very strong vesication, and .001 gra. of cantharidin dissolved in a drop of alcohol also produces marked vesication. RESINS, OLEO-RESINS, GUMS, BALSAMS. 554. Many of the bodies of the turpentine and essential oil series above mentioned, when exposed to the air, undergo a process of oxidation or hardening, become viscid or solid, and exhibit an acid reaction. Such bodies, when brittle and solid, are called resins ; when composed of unoxidized oils mixed with resins, they are called balsams ; when the resins exist in the juices of plants mixed with gum, sugar, etc., they are called gum-resins. Each one of these bodies is generally a mixture of several bodies, and, therefore, no definite chemical formula can be given. They are insoluble in water, but soluble in strong alcohol, turpentine and 320 MEDICAL CHEMISTRY. glycerin ; many are soluble in ether and benzene (separation from gums) ; many are weak acids, whose alkaline salts form the resin soaps of the market. Many resins are used in medicine, in the manufacture of varnishes,, sealing wax, and salves. The resins are soluble in alcohol. The resins soften when heated, but do not vaporize. The separation of resins from volatile oils and acids, is effected by distillation with water ; from gums, by fusion and straining at ioo° C. (212° F.); and from each other, as well as from foreign substances, by properly selected solvents. Under the name of resins the following substances are classed : Amber, colophony, (rosin), copal (anime), dammar, lac. Bur- gundy pitch, mastic and sandarac, which are used in the arts for making varnish, and for other uses. The following are some of the resinous substances used in med- icine : — Arnicin, from arnica flowers ; castorin from castoreum ; cannabin from cannabis indica ; dragon's blood an exudate from the fruit of Caiafiius draco ; elemi a resin from Central America, an exudate from the Amyris elemifera. A resin found in ergot of rye, guaiacum, an exudate from the wood of the Guaiacum officinale ; jalap, the resin of jalap root; labdanum, an exudate from the bark of several varieties of the cisius grown in Greece ; podophyllin, from the May- apple root; pyrethrum from pellitory root, and rottlerin, from the kamala, a shrub grown in East Indies. Dammar is the exuded and hardened sap of the Dammara orientalis, a coniferous tree growing in the East Indies, Aus- tralia and New Zealand. It is also used in the manufacture of varnish. Lac is a resinous incrustation produced on the bark of the twigs of various tropical trees, by the puncture of the " lac insect." This crude gum is called " stick lac " in commerce. Shell-lac, or shellac, is formed by melting, straining and drying it in thin sheets. In the preparation of shellac the coloring matter is separated, and is sold under the name of lac- dye. It is easily soluble in alcohol. Lac is used extensively in the manufacture of varnish, lacquers, sealing wax, etc. Mastic is an exudate from the bark of certain trees found in the island of Chios in the Mediterranean. It occurs in pale yellow, transparent, brittle tears, soluble in alcohol and turpen- tine, and is used for making varnish. Guaiacum is a brittle, pulverizable solid, of a reddish-brown RESINS, OLEO-RESINS, GUMS, BALSAMS. 32 1 color. The gum dissolves in alcohol. It readily undergoes oxi- dation, producing bright colors. A mixture of the official tincture and oil of turpentine is frequently employed as a reagent for detecting blood in urine, with which it strikes a blue color. Only the most common resins can be described. Common Resin — Rosin — Colophony — is the residue left by distilling the balsam or crude turpentine of the pine with water. Turpentine distils off and leaves a yellow or brown, brittle, shining mass, which when melted forms the commercial rosin. It usually has a sp. gr. of about 1.04 to i.io. It is nearly tasteless, but leaves a characteristic nauseous after-taste. It is insoluble in water, but is soluble in alcohol, ether, chloro- form, and in the fixed and volatile oils. It is soluble in caustic, and even carbonated alkalies, forming soaps soluble in water. Colophony is composed chiefly of several resin acids, the chief of which is abietic acid, C44H62O4. Sylvic acid, CjoHaoOz, exists in small quantity. It may be detected in mixtures, by boiling 5 gms. with 20 c. c. of pure nitric acid, diluting when cold with an equal volume of water, and adding ammonia. If resin be present a blood-red solution is produced. Rosin is used in the manufacture of varnishes, sealing-wax, lamp-black and the common yellow soaps. Copal, or Anime, is a yellow, hard, brittle, more or less transparent solid, found on the coast of Africa, and is dug out of the soil by the natives. It is a fossil resin of recent origin. It is very hard, and soluble with great difficulty in alcohol and essential oils. It makes the best resin varnishes. Amber is also a fossil resin, found on the shores of the Baltic in Prussia. It is a very hard, tough and transparent or translucent yellow solid. It is used for making beads, mouth- pieces of pipes, and for the manufacture of superior varnish. The best known oleo-resins are the oleo-resins of aspidium, capsicum, cubeb, copaiba, lupulin, pepper, ginger, male fern, frankincense, Canada balsam and Canada pitch. They are usually extracted from the plants with ethylic ether, using 150 parts of ether for 100 parts of the plant. (U. S. P. method.) The ether is then distilled off, and the oleo-resin kept in a well stoppered bottle. The principal gum-resins are aloes, ammoniacum, asafoetida, galbanum, myrrh, olibanum, scammony, gamboge, and eupho- rium. All but the last are official. They occur in commerce mostly as compact masses of a yellow or brown color, composed of tears glued together with a hardened, gummy mass. 28 322 MEDICAL CHEMISTRY. They are usually brittle enough to be pulverized and are solu- ble in alcohol or ether. When rubbed with water, in a mortar, they form milk-white emulsions. The most of them are soluble in caustic alkalies. The chief balsams are benzoin, Peru, storax, and tolu. Gum benzoin, as it is frequently called, occurs as rectangular blocks, which consist of milk-white tears agglutinated by a brown resin. It has a pleasant, balsamic odor, and is soluble in alcohol, forming tincture of benzoin. It contains from 12 to 20 per cent, of benzoic acid, which can be sublimed from it by gentle heat. It usually contains a small quantity of cinnamic acid and some- times vanillin. It contains several resins. Balsam of Peru, storax, and tolu contain cinnamic ethers, resinous matter, and volatile oils. Benzoic acid is found in balsam of Peru and tolu. They are all soluble in alcohol. THE BENZENE OR AROMATIC SERIES, Ci,H2„_6. 555. The compounds of this series differ from all others thus far mentioned, in the structure of their molecules, in that the car- bon atoms are arranged in the form of a closed chain, at the angles of a regular hexagon, H H ^//\^ H I II H ^Xq/*^ H H /. e., every carbon atom is the equivalent of every other, while in the other hydrocarbons, we have noticed a difference between the end ones and the others, The H atoms in benzene are all alike in behavior. We arrive at the idea that the C atoms are in a closed chain by the following facts. Benzene takes up two, four, or six atoms of H, CI, or Br, according to the conditions of the experiment. Benzene thus becomes, in the first case, under the prolonged action of HI, CaHu, but the continued action of HI does not impart to it any more H. If the carbon atoms were arranged in an open chain, it would become CeHi^. H,C — C — C — C — C — CH, II II II II H„ Hq Ho Hn THE BENZENK OR AROMATIC SERIES. 323 The hexa-chloride of benzene (CeHsCle), when once formed, refuses to take up more chlorine. The same is true of the hexa-bromide. In order to give an explanation of these facts, it is necessary to assume one of the following graphic formulae as the proper arrangement of the C atoms in its molecule : — H H H C C C ^ \ / \ / \ HC CH HC CH HC, ,CH 1 II HC CH 11 HC II CH \ Hc/ . ■ ■ . 0.065 0.039 0.040 0.034 0.027 0.047 Beers and porters contain from i to 10 per cent., average about 4 to 5 per cent, by volume. The average of extractive matters (dextrin, cellulose, sugar, lupulin, and hop resin) is 4 to 15 in ale, 4 to 9 in porter, and about 5 per cent, in beer. All alcoholic beverages are subject to gross adulterations. Artificial beverages are frequently sold in all markets. The following table illustrates the composition of the follow- ing malt liquors (Allen) : — Sp. Gr. Alco- hol. Solid Matter or Extract. Free Acid. Ash. Pilsen Lager Hanoverian Lager (average of 20 samples) • . American Lager (average of 19 samples), ....... Bass's Pale Ale Alsop's Pale Ale Guiness's Stout Dublin " Munich Lager, 1.013 1.017 1.016.2 1.013.8 1.014.4 1.124.4 1.021 3-SS 4.01 2.78 6.25 6.37 6.66 5-oS 5-50 4-75 S-'S 6.34 6.05 6.98 4-44 7.24 5.48 8.71 7.08 0.12 0.14 0.24 0.20 0.23 0.18 0.15 .20 •24 579. Propyl alcohol, or ethyl carbinol (CjHjOH), is 342 MEDICAL CHEMISTRY. found in the latter portions of the distillate in rectifying crude al- cohol. Its sp. gr. is 0.82. It boils at 97.5° C. (297° F.). It may be separated from its mixture with water by saturating with CaClj, which absorbs the water and allows the alcohol to separate as a layer. When oxidized, it yields propyl aldehyde (CaHjOH) and propylic acid (QH5COOH). 580. Butyl Alcohol (C4H9OH).— There are four butyl alco- hols known. The butyl alcohol of fermentation is formed during the alcoholic fermentation of sugars. It may be obtained by repeated fractional distillation of the heavier portions that come over at the end of the process. It is a colorless liquid, boiling at 116° C. (240.8° F.). It is more poisonous than ethyl or methyl alcohol. 581. Amyl Alcdhol, Fusel Oil,* Potato Spirit, Propyl Carbinol (C5H11OH). — Of the eight possible theoretical amylic alcohols seven are known : — HO \ HjC — C — C CH, H, H, H, Normal amyl alcohol or primary amylic alcohol. H OH I I H3C — C — C — CH. I II C H, Secondary amylic alcohol, iso-butyl carbinol, or iso-amylic alcohol. H HO c — CH,— cir, I CHj CH3 Di-elhyl carbinol. HO H, \ II HC — C ■ I H, 11 C CH, CH, Methyl-propyl carbinol. HO \ H, H,C- H I -C- CH.OH I ■ c — c n. Di-methyl-ethyl carbinol, tertiary amylic alcohol, or amylene hydrate. H H Secondary isobutyl carbinol. O— H I /CH, H,C — C — C( I I ^CH, H H Methyl-isopropyl carbinol. * Fusel oil, properly speaking, is a mixture of several alcohols, of which amyl alcohol is one. MONATOMIC ALCOHOLS. 343 Of these compounds the only ones of interest are iso-amyl alcohol and amylene hydrate. Amyl alcohol (Iso-amylic alcohol) (CsHuOH) is formed in small quantities at the same time with ethyl alcohol, during the fermentation of barley, corn, and especially potato mash. It is prepared from the residue left in the still after the common alcohol is distilled off. The product coming over at 132° C. (269° F.) is that collected. It is a colorless, oily liquid, possessing a peculiar, irritating odor which excites coughing, and a burning taste. It is not raiscible with water, but mixes in all proportions with alcohol and ether. It is a good solvent of certain alkaloids. Taken internally, both in the form of vapor and when taken by the stomach, it acts as a poison, producing dizziness, headache, and intoxication. Much of the unwholesomeness of imperfectly rectified spirituous liquors arises from their contamination with fusel oil. The principal uses of fusel oil are in the preparation of varnish, and as a source of amyl ethers, which are used extensively to prepare artificial flavoring extracts. Thus, the acetate has the odor of pears, and is used by confectioners under the name of "pear oil," while the valerianate is used to give the flavor of apples, and is called " apple oil." 582. Amylene Hydrate, or Di-methyl-ethyl-car- binol, CH3— CH2— COH=(CH3),.— When amyl alcohol is heated with ZnClj, amylene, CsHu,, is formed ; this combines with hydriodic acid to form ethylene iodide. This iodide when treated with AgO gives tertiary amylic alcohol or amylene hydrate. This is a colorless liquid, boiling at 108° C. (226.4° F.), with a peculiar odor resembling menthol. It is soluble in eight parts of water and freely soluble in alcohol. It has been employed, in doses of 20 to 25 grains, as a hypnotic. Among the higher monatomic alcohols are the following : — 583. Cetylic Alcohol, QsHjaOH, formerly termed Kthal, obtained by saponifying spermaceti (Cetaceum, U. S. P.), which consists of palmitate of cetyl. Spermaceti is a solid crystallized fat accompanying sperm oil in the head of the sperm whale. Cerylic Alcohol, C27H55OH, is obtained in the same manner from Chinese wax. 584. Melissic Alcohol, CsoHjiOH, is obtained from that por- tion of beeswax soluble in alcohol, which is composed of melissic palmitate. Yellow wax (cera flava, U. S. V.) and white wax, which is bleached by exposure to moisture, air, and sunlight, are 344 MEDICAL CHEMISTRY. prepared from the honeycomb. Beeswax contains, besides . melissic palmitate, cerotic acid and cerolein. The adulterants found in wax are paraffin and ceresin. Both paraffin and ceresin reduce the melting point of wax, which should not be lower than 63.3° C. (146° F.). Pure wax will yield not more than 3 per cent, to cold alcohol, whereas resin, if present, would be extracted by the alcohol. Both paraffin and ceresin are insoluble in alcohol. 585. Diatomic Alcohols (glycols) are of little interest to the physician. They may be regarded as being derived from two molecules of water in which one atom of H from each molecule has been displaced by a diatomic radical. Glycol {C2Il^(pB.)2), or Ethene Alcohol, is a colorless, transparent, almost odorless liquid, less mobile than alcohol, having a sweetish taste and boiling at 97" C. (386.6° C). It dissolves in water and alcohol in all proportions. It is prepared by decomposing ethene dibromide with potassium carbonate. It has no practical applications. TRIATOMIC ALCOHOLS, OR GLYCERINS. (OH 586. Ordinary Glycerin— Glycerol, CsHj-l OH, was dis- (.OH covered by Scheele in 1779, and was called by him the sweet principle of oils. It is prepared on a large scale from the neu- tral fats, as aside product in the manufacture of soap and candles. These fatty bodies are composed of fatty acids in combination with glyceryl (C3H5), the radical of glycerin ; i. e., they are com- pound ethers of the fatty acids and glyceryl. On treating these ethers with alkalies, a salt of the alkali with the acid is formed, termed a soap ; the glycerin is set free by the reaction ' and re- mains dissolved in the water present. This process of decom- posing a compound ether into an alcohol and acid, or salt of the acid, is called saponification. Neutral fats can also be saponi- fied by treating them with superheated steam, which is the pro- cess now usually employed in candle factories. The glycerin is freed from the water by evaporation, and finally, by distillation with the aid of superheated steam. Glycerin is also formed during alcoholic fernnentation, and is found in wines etc. It is a colorless, syrupy liquid, possessing a sweetish taste and no TRIATOMIC ALCOHOLS, OR GLYCERINS. 345 odor; its density is 1.28 at 15.5° C. (60° F.). The officinal glycerinum has a density of 1.25. It is soluble in all propor- tions in water and alcohol, but not in ether. It is hygroscopic, and absorbs water readily until it has absorbed twice its own volume. Its range of solubility is large, as will be seen by the table in the appendix. When heated in air, it boils at 290° C. (S54° F.), and distils with partial decomposition. At low tem- peratures, it forms, under certain circumstances, a crystalline mass. When heated in the air to a high temperature, it takes fire and burns, leaving no residue. Boracic acid imparts a green color to its flame, or to a flame directed upon a platinum wire moistened with it. This is one of the most convenient tests for boracic acid. Chemically, glycerin is, as above stated, a tri- atomic alcohol ; /. e. , it contains three hydroxyl groups. When ( O.OH oxidized, it yields glyceric acid, C3H3 \ OH. It is capable in (oh certain circumstances of undergoing fermentation with yeast, producing ethyl alcohol, propyl alcohol, butyric and caproic acids. It unites with the alkalies and alkaline earths, the com- pounds being soluble in water. It prevents the precipitation of copper hydroxide by sodium or potassium hydroxide, and has been recommended for this purpose in the preparation of Fehl- ing's test solution for glucose. Glycerin is sometimes adulterated with glucose, cane sugar syrup, and water. The first and second of these will usually be easily detected by adding a solution of sodium hydroxide (caustic soda) and enough copper sulphate to impart a blue color, and boiling for a few minutes, when, if these be present, red cuprous oxide will be precipitated. The presence of water may be detected by taking the specific gravity, which should not be below .1.25. Glycerin is the basis of the manufacture of nitro- glycerin, used in various forms of blasting agents, such as " dual- ine," "dynamite," " giant powder," "rend rock," etc., which are usually composed of nitro-glycerin and some porous sub- stance in powder form. When glycerin is saturated with gaseous HCl and then heated for several hours to 100° C, mono-chlor- and di-chlorhy- drines are formed. C3H5 (0H)3 + HC1= C3H5(OH)jCl + HjO. CjHsCOH), -t- 2HC1= CjHsOHCl, -|- 2HjO. Sulphuric acid combines with glycerin to form glycero- 30 346 MEDICAL CHEMISTRY. sulphuric acid. Glacial, or metaphosphoric, acid forms glycero-phosphoric acid. C3H5(OH),OPO_=0, = H,. This acid is one of the decomposition products of lecithin and protagon, two complex bodies found in nerve substance, espe- cially of the brain. The acid itself has been found in the brain, nerves, muscles, yolk of egg, bile, and pus. The phosphorus present in nerve matters probably exists in the form of either lecithin or protagon, both of which contain glycero-phosphoric acid. The ethers of glycerin and organic acids will be referred to later. (See Neutral Fats.) 587. Nitro-glycerin, or Glyceryl Trinitrate, f NO, C3H5 ] NO3. ( NO3 When glycerin is allowed to flow in a slow stream into a mixture of strong nitric and sulphuric acids, kept cold by a freezing mix- ture, and the mixture afterward thrown into a large quantity of cold water, there separates out a heavy, colorless, poisonous oil — nitroglycerin. It crystallizes at — 20° C. (4° F.); sp.gr. 1.6. When inflamed in air, it burns quietly and rapidly ; but when ignited by percussion or quick heating, especially in a confined space, it explodes with terrific violence, and hence is much used in blasting. In order to make this explosive agent less danger- ous to handle it is usually mixed with some inert powder, such as clay, diatomaceous earth, sawdust, etc., and is then sold under the name of dynamite, dualine, rend-rock, and giant powder. Under the name of Spiritus glonoini, a one per cent, alcoholic solution is official, and is used as a. heart stimulant. Tetratomic Alcohols. — None of this class of alcohols are of sufficient importance to be discussed here. ■ HEXATOMIC ALCOHOLS. Formula, Cn H,_4(0H)|,. 588. In the hexatomic alcohols the six hydroxyl radicals are united to six different carbon atoms, so that there must be six carbon atoms in the nucleus. This class of alcohols include — Mannitol, C6H8(OH)5. Dulcitol, CjH8(0H)j. 589. Mannitol — Mannite. — This is the sweet principle of manna, and is found widely distributed in the vegetable kingdom. THE CARBOHYDRATES. 347 It occurs in celery, fungi, and seaweeds, in the sap of the larch, the exuded sap of the apple, cherry, lime, etc., and the exuded sap of Fraxinus ornus, which in the dry state forms commercial manna. It may be prepared artificially by acting upon grape sugar with sodium amalgam (nascent hydrogen), or by the so- called mucous and the butyric fermentation of sugar. To obtain it from manna, dissolve in half its weight of boiling water, add some albumen, to clarify, and filter through cloth. On cooling, the mannite separates out. It may also be obtained pure by extracting manna with hot alcohol, and crystallizing. It forms fine, silky needles when crystallized from alcohol, but large, transparent, rhombic prisms from the aqueous solution. Mannite is intensely sweet, sparingly soluble in cold, readily soluble in hot water and alcohol, and insoluble in ether. It can readily undergo lactic and butyric fermentations, but not alcoholic. It combines with many metallic oxides, and also forms a large number of compound ethers. Mild oxidation produces mannitose, C6H,0(OH)5. By further oxidation, it forms mannitic acid, C6H6(OH)5CO.OH, and saccharic acid, C,H,(OH), j (-.o;oH. 590. Dulcitol — Dulcite. — This isomeride of mannite is found in dulcose, or dulcite manna, a crystalline substance from Madagascar. It is found in several plants. It has been pre- . pared from milk sugar, by treatment with sodium amalgam. The properties of dulcite resemble those of mannite. 591. Sorbitol — Sorbite — is a third isomeride of mannite, found in the mountain ash. THE CARBOHYDRATES. 592. Closely allied to the alcohols is a class known as carbo- hydrates. They contain six, or a multiple of six, atoms of carbon and twice as many of hydrogen. Some of the bodies belonging to this class are found in the human body, as glycogen, dextrose or glucose, maltose, inosite, and lactose. They may be divided into three groups : — (i) Saccharoses. (2) Glucoses. (3) Amyloses. C12H22O11 CeHjgOfl. CoHifiOs. + Cane Sugar. (A)„= + 73.8°. + Dextrose (A)„ = + 56.0°. + Starch. -j- Milk Sugar. = + 59-3°- — (Grape Sugar.) -f Glycogen. -j- Maltose. = -j- 140°. — Levulose := — 106°. -f" Dextrin. -j- Melitose. + Galactose. — Inulin. 4- Melizitose. — Sorbin. Gums. -j- Mycose. Eucalin. Cellulose. -|- Synanthrose. Inosite. Tunicin. 348 MEDICAL CHEMISTRY. All these compounds occur ready formed, either in plant or. animal organisms. The three groups are connected by a close relationship ; indeed, those of i and 3 are easily converted into the glucoses by ferments or by boiling with dilute acids, by which water is added to them. The saccharoses and amyloses may be regarded as anhydrides of the glucoses. The chemical constitution -g is s 52 Dextro - rota- tory power diminished. 3" •6 ctt O 1 z s 'a 1 u u en u 6 *£• 1- rt Aboo III o u ft "5. to ■s i p. 1" 1 •a •0 . 11 J"* i u A S I b Hi Si i! u ! o 2 ■s S (4 O Z •s 2 '5, 1 ■s a ■5. 11 J'" 1 s 1 P II X 1* '4 li . it as go: 1^ t- o g Si rt ■li 1= ■to _o "o II ay nt u xb ^0 Q ii ■g § M II .S.H 11 ■a "1 = 11 n. ifi eg c^ 111 feji S3 tfll 1:11 2|-a-"5 £ 1 u bO 11- |i S °.c-°.S 4 .ii|4 o*j 5 c C.S- T3 Ifll' ll I o.s:9 ■«^-- ES.S §1- = «!=?. i 1 0. 1 B C .2 J *o 1 > 1 II 3 0. ■S.S 4 00 350 SACCHAROSES. 351 phuric acid and manganic oxide, a large quantity of formic acid is formed. Cane sugar forms a series of metallic compounds called sucrates or saccharates. An aqueous solution of sugar will dissolve calcium, barium, magnesium, and lead oxides, and, with an alkali, copper and ferric oxides also. The barium salt crystallizes well. When cane sugar is injected into the blood-vessels of an animal, it is eliminated in an unaltered condition, and is thus shown to be unassimilated. It may be introduced in large amounts by the alimentary canal, and none of it appears in the urine. From this it appears that it undergoes a change during or before absorption. This change is the result of the action of soluble ferments appearing in the small intestine. Cane sugar readily undergoes lactic fermentation in the presence of sour milk, to which zinc oxide is added for the fixation of the acid. It does not form a compound with phenyl hydrazin, and by this test it may be distinguished from the other sugars. 595. Lactose— Milk Sugar — Saccharum Lactis (U. S. P-) CCijHjjOu -\- HjO). — This is an important ingredient of the milk of mammals, and is prepared principally from cow's milk by evaporating the whey after removing the curd for the manu- facture of cheese. Cow's milk contains from 4 to 5 per cent, of sugar, while woman's milk contains from 6 to 7 per cent. It crystallizes in large, hard prisms, has a feebly sweet taste, and is soluble in 6 parts of cold water. Yeast does not ferment it. Lactic and butyric fermentations take place readily. Oxidizing agents yield mucic and saccharic acids. Like cane sugar, it forms compounds with metallic oxides, and reduces alkaline copper solutions. Ten c. c. of Fehling's fluid, which is reduced by 5 mgr. of glucose, is reduced bv 6.7 mgr. of lactose. It does not reduce Birford's reagent.* When boiled with dilute mineral acids it yields equal molecules of dextrose and galactose, which are fer- mentable. 596, Phenyl Lactosazone (C24H3jN409'). — This compound of lactose with phenyl-hydrazin is formed by adding to a solu- tion of lactose equal parts of phenyl-hydrazin hydrochlorate and sodium acetate, and heating on a water bath for one-half hour ; or by adding 10 to 15 drops of pure phenyl-hydrazin and an * Barford's reagent is composed of I part of copper acetate in 15 parts of water. To 200 c.c. of this solution add 5 c.c. of acetic acid containing 38 per cent, of glacial acid. 352 MEDICAL CHEMISTRY. equal number of drops of strong acetic acid, and warming. It is soluble in 80 to 90 parts of boiling water and melts at about 200° C. It crystallizes readily in the form of yellow needles, which are usually aggregated into clusters. Pure lactose is not affected by yeast. Milk is capable of alcoholic fermentation under the influence of certain ferments. This has been employed from the earliest times by the inhabit- ants of Russia and Asia Minor in the preparation of kumyss and kephir from mare's milk. In recent years these fluids have attracted much attention for their supposed therapeutic virtues. Very little is known of the real nature of the changes which occur in this fermentation. Kephir ferment is a commercial article in Russia, Austria, and even in this country. Lactose, when injected into the blood-vessels, appears unaltered in the urine. It also sometimes appears in the urine in the early months of lactation or during reabsorption of milk, after wean- ing. It is, therefore, non-assimilable. But when taken in the alimentary canal it is perfectly assimilated. It has not been observed to undergo any change in the alimentary canal under the action of any of the secretions. Hence, the change prob- ably takes place during absorption through the intestinal walls, as in the case of maltose. When administered in large doses lactose acts as an active diuretic. Milk loses this diuretic effect on being boiled. 597. Maltose — Malt Sugar, djHajOn.HjO. — This sugar is formed by the action of malt diastase upon starch. It may also be formed by the action of dilute acids upon starch paste, but in this case the maltose is itself converted into dextrose. This is the chief sugar formed by the action of saliva and pancreatic juice upon starch paste or glycogen, being accompanied in the case of pancreatic digestion by a variable but distinct amount of dextrose. Maltose is very soluble in water. It is also soluble in alcohol, but less so than glucose. It crystallizes, with difficulty, in fine needles. It is not easy to distinguish from glucose by qualitative tests. Its rotatory power is -|- 140, while that of dextrose is 52.5 under the same conditions. With Fehling's solution, the amount of CujO which separates is only about ^ of that which would be reduced by an equal weight of dextrose, or 6.6 parts of dextrose reduces as much copper as 10 parts of maltose. Barford's reagent is not reduced by maltose, while it is by dextrose. In this respect maltose resembles lactose, and this test serves to distinguish it from dextrose. Maltose forms with phenyl-hydrazin, in the presence of acetic GLUCOSES. 353 acid, Phenyl maltosazone, C,2H2„09.(C6H5N2H)j. It crystal- lizes in minute yellow needles and is characterized by being solu- ble in about 75 parts of boiling water, and is still more soluble in hot alcohol. If maltose be injected into the blood-vessels it appears unaltered in the urine. To be assimilable it must, there- fore, be changed before or during absorption. GLUCOSES. CftHiaOg. 598. Dextrose — Glucose— Grape-sugar, CgHijOe. — This sugar is widely diffused through the vegetable kingdom, occurring in grapes, honey, in most sweet fruits, sprouting grains, etc., usu- ally mixed with an equal rruount of levulose. It occurs in small quantities in the blood, yolk of eggs, and in larger quantity in diabetic urine. It is manufactured on a large scale from corn starch, by boiling with dilute sulphuric acid, neutralizing with lime, drawing off the clear syrup after settling, and evaporating it down to a thick syrup and allowing it to crystallize. Dextrose is less sweet than cane sugar, 2j^ parts of the former giving the sweetening power of 1 part of the latter. It is sometimes used to adulterate the light brown varieties of cane sugar. When present in considerable quantities, 5 per cent., it may often be detected by its property of mashing between the teeth instead of crushing like cane sugar. Dextrose crystallizes with some difficulty, and, as usually met with in the market, it does not present to the naked eye a distinct crystalline appearance. It easily undergoes oxidation, especially in alkaline solutions, and thus acts as a re- ducing agent. It readily reduces silver, copper, bismuth, and mercury salts in alkaline solutions. Silver, if ammonia be present, is reduced to the metallic state and deposits as a brilliant mirror on the sur- face of the vessel in which it is heated. The ordinary methods of detection and estimation of dextrose dejjend upon its reducing power. Fehling's solution, which is in common use both as a qualitative and quantitative test for dex- trose, is a solution of 34.64 grms. of pure crystallized copper sul- phate, 173 grms. of Rochelle salt, and 80 grms. of sodium hy- droxide in a liter of distilled water, i c.c. of this solution is exactly reduced and decolorized by 5 milligrams of dextrose. For qualitative detection, alkaline solutions of copper, bismuth, indigo-carmine, picric acid, or silver may be used. Dextrose 354 MEDICAL CHEMISTRY. undergoes alcoholic fermentation with great ease and is used in large quantities in making beer. Dextrose readily forms compounds with metallic oxides and many salts. When heated, many of these compounds, more par- ticularly those of copper, bismuth, and mercury, decompose, the decomposition being accompanied by a precipitate of either the metal or the oxide. 599. Phenyl Glucosazone, C6Hii,04.(C6H5N2H)2. — This compound, produced by dextrose with phenyl-hydrazin, occurs in yellow needles. It is prepared under the conditions mentioned under lactose, for the preparation of phenyl lactosazone. The formation of these crystals is employed as a test for glucose in urine. To 50 c.c. of the suspected urine add i or 2 grms. of phenyl-hydrazin hydrochlorate, 2 grms. sodium acetate, and heat on a water bath for a half hour ; or, add 10 to 20 drops of pure phenyl hydrazin and an equal number of drops of 50 per cent, acetic acid, and warm as before. On cooling, if not before, the glucosazone separates out as yellow crystalline needles. This test will detect 5 grms. of glucose per liter. Dextrose readily undergoes alcoholic, lactic, and butyric fermentations. When it is mixed with finely divided gastric membrane, it is rapidly changed into lactic acid. There is some evidence of the existence of unorganized ferments in the stomach which can con- vert lactose and dextrose into lactic acid, and this is probably the origin of a part of the lactic acid found in the gastric con- tents during digestion. It is a readily assimilable sugar, though not so readily as levulose. 600. Levulose. — This sugar occurs mixed with dextrose in the natural sources of that sugar, mentioned above. It is obtained with dextrose in invert-sugar, prepared by heating cane sugar with dilute mineral acids. It differs from dextrose in being less fermentable and in its rotatory power, which is left-handed instead of right-handed ; the other differences are of minor importance, except sweetening power, which is greater in this sugar than in grape sugar. Levulose is easily assimilated when pure, and is completely and easily burned in the body. Its use does not increase the sugar in the urine of diabetics. It has been recently introduced as a sweetening agent for diabetics under the name of diabetin. It yields a compound with phenyl-hydrazin, identical with that derived from dextrose. It forms a compound with calcium hy- droxide, which, unlike that yielded by dextrose, is extremely insoluble, and may be employed for the separation of these two sugars. AMYLOSES. 355 6oi. Inosite, CjHuOe.zHjO = (CH0H)e.H20, is optically inactive and does not react with phenyl-hydrazin. It occurs sparingly in the human body. It has been found in the heart, muscles, in diabetic urine, and in that of Bright's disease. It has also been found in the lungs, kidney, spleen, liver, and brain. It occurs in abundance in the vegetable kingdom, especially in unripe beans, from which it may be con- veniently prepared. Its sweet taste is its only resemblance to the sugars. It is now believed to be a derivative of benzene, and not a sugar "at all. Pure inosite forms large, efflorescent, rhombic tables, or occurs in tufted lumps of fine crystals. It is readily soluble in water, slightly so in dilute alcohol, and insoluble in strong alcohol and ether. 602. Galactose, or Cerebrose (CgHijOe), is formed, together with dextrose, when lactose is boiled with dilute mineral acids. The two sugars may be separated by crystallization, and by the fact that galactose is soluble in absolute alcohol, while dextrose is not. In general reactions and behavior galactose resembles dex- trose, but has a considerably greater rotatory power. It yields phenyl galactosazone with phenyl-hydrazin, which has the same composition and very similar properties as the corresponding compound of dextrose. Galactose is fermentable with yeast, but less readily than dextrose. 603. Sorbinose, or Sorbin (CgHijOe), is foundin ripemount- ain ash berries. It is not fermentable. It is very sweet, and easily soluble in water. It crystallizes in hard, rhombic crystals. (3) AMYLOSES. (Ci2H2oOio)n. 604. Starch, or Amylum. — This body is found in nearly all plants. It is most abundant in the cereals, rice, potatoes, and the seeds of plants. Starch occurs in the form of microscopical granules inclosed in the cells of the plant where they occur, very much as fat occurs in adipose tissue. The granules, examined under the microscope, are seen to be possessed of a distinct organized structure, which is different in each different kind of starch. They show, under the microscope, several concentric markings, arranged around a nucleus, or hilum, which is situated nearer one edge. The sizes and markings of the starches from 3S6 MEDICAL CHEMISTRY. the various sources vary sufficiently to admit of identification. This is an important fact in the detection of adulterations in food and drugs. The appearance of a number of the starches of the market, as seen under the microscope, are shown by the plate on the opposite page. Starch is prepared by grinding the grain or vegetable, and then suspending it in water, or spreading it on a sieve and run- ning water upon it. By this means the starch granules are washed out of the cells, and remain suspended in the water. This milky- looking liquid is allowed to settle, when the starch fall? to the bottom. This sediment is taken out, dried, and sent into the market. Wheat starch is often prepared by suspending the flour in water and allowing it to stand until the gluten is dissolved by putrefactive fermentation, when the starch may be washed and dried. Starch is insoluble in cold water, alcohol, and ether. Heated with water to a little above 60° C. (140° F.), the contents of the granules swell up, burst the envelopes, and escape into the water. It appears at first as a very fine powder, but afterward disappears and forms an apparent solution, which, if concentrated, forms, on cooling, a jelly-like mass, called starch-paste. On long boiling, starch enters into a soluble form. The same change is produced by a dry heat of 100° C. (212° F.), by diastase, or dilute sulphuric acid. With diastase it soon passes into the form of maltose and dextrin. It forms metallic compounds with lead, lime, and barium oxides. Soluble starch is precipitated by alcohol and solutions of subacetate of lead. Starch dissolves in cold, concentrated nitric acid ; on the addi- ,tion of water, xyloidin, a white powder, separates. The most characteristic reaction of starch is the dark blue color it forms with free iodine. This blue iodide of starch is easily decomposed, and dissociates when the solution is heated, but re-forms on cooling. 605. Dextrin, or British Gum, is an amorphous, yellowish- white, gum like body, readily soluble in water. It is formed by heating starch above 150° C. (302° F.), or by the first action of malt diastase, or hot dilute sulphuric acid upon starch. This change is a progressive one. When diastase or pancreatic fer- ment is added to gelatinous starch (starch paste), it is liquefied in a few moments and becomes soluble starch, which is represented by the formula, loCCuHjoOio). This is gradually hydrated under r- i^Ck-^^^ ^^ 1 Potato Stveli 4 SlVincaiit AirawToot 7. Jtio Arrowroot 2 Bennnd&J^rroitToot %. Sago of CoAnneroe 8. l^tpiooft 3 Toiu lea HoIb 6 Fort 'SoA Mivtm^t. 9. Valse {After Allen). 358 MEDICAL CHEMISTRY. 607. Cellulose, or Lignin (C6Hii,06)„, or (C6H,02(OH)a.-^ This forms the principal part of the solid framework of plants. The pure substance may be prepared by treating raw cotton or linen fibre with potassiumhydroxide, acids, and ether, to remove foreign matters. It is a white solid, exhibiting the structure of the fibre from which it is obtained. It is slightly soluble in a solution of cupric hydroxide in ammonium hydroxide. On the addition of an acid to this solution it is precipitated as a white amorphous mass. Cellulose is insoluble in water, alcohol, ether, and all ordinary solvents. Strong sulphuric acid dissolves it, and on diluting with water white flakes separate. When boiled with dilute sulphuric acid, it is converted into dextrin and dextrose. When cotton-wool is steeped in a cold mixture of i part of strong nitric and 3 parts sulphuric acid for a few minutes, squeezed as dry as possible, placed in fresh acid for 48 hours, then pressed dry, and finally washed thoroughly in water, then in a weak solution of sodmm carbonate, it possesses, when dry, great explosive properties, and is called gun cotton, C6H,02(N03)3. The appearance and physical properties of the cotton remain un- changed, but it becomes a nitrate of cellulose, the composition varying with the mode of preparation. Pyroxylin is a nitro-cellulose, containing less NO3 groups than gun cotton. It is prepared by dipping cotton into a mix- ture of 14 parts HNOjand 22 parts of H^SOi, allowing it to steep for 10 hours, or until it is soluble in a mixture of alcohol and ether d to 3), then removing and washing it in cold water. It is used as a source of collodion. Collodion is prepared by dissolving 4 parts of pyroxylin in a mixture of 70 parts of ether and 26 parts of alcohol. Flexible collodion is a mixture of 92 parts of the above, 5 parts turpen- tine, and 3 of castor oil. Styptic collodion owes this property to 20 per cent, of tannic acid. If dry, unsized paper be dipped into a cold mixture of 2 parts of sulphuric acid and i of water, for a few seconds, and then washed quickly in cold water containing a little ammonia, it is rendered very tough and strong, and is called parchment paper. VEGETABLE GUMS. 608. The gums are amorphous bodies, more or less soluble in water, but insoluble in alcohol, and are converted into one of the glucoses by dilute H2SO4. They are found in plants and are of unknown constitution. They are non-volatile and have little or VEGETABLE GUMS. 359 no taste. They are non-crystallizable and eminently colloidal. From this fact they are difficult to purify. Many of them appear to be closely related in composition to starch, while others have a different composition. They are distinguished from the sugars by being incapable of fermentation by yeast, and being insoluble in alcohol. The gums are distinguished from" starch and dextrin, by giving no color with a solution of iodine. They do not yield ammonia when heated with soda lime, which dis- tinguishes them from the albuminoids. They have not been sufficiently studied to admit of accurate classification. Gum Arabic, or Gum Acacia, is a dried extraction from the bark of different kinds of acacia. Strictly speaking, gumarabic is the generic name. Gum acacia is applied only to the purer qualities employed in medicine. ■ They are obtained chiefly from the Sudan. It occurs in rounded, irregular masses, which dissolve in cold water to form a thick, viscid solution. Gum arabic con- sists essentially of the calcium salt of arabic acid, or arabin. Arabic Acid, CsHjoOsOHj, when heated with dilute H2SO4, splits up into a series of glucoses or arabinoses, of which four varieties have been recognized. Gum-senegal forms yellowish or reddish lumps, often the size of a pigeon's egg. It is less soluble than the true gum arabic, and its solution soon becomes dark in color. Gum arabic should not contain more than 4 per cent, of ash. The powder should not be colored blue (absence of starch) or red (absence of dex- trin) by iodine. Its solution should give an acid reaction with litmus paper. Gum Tragacanth is a gummy exudation from Astragalus gummifer and allied species. It occurs in tear-like masses, strings, or bands, which are usually marked with ridges. Gum traga- canth is usually white or yellowish white in color, but inferior varieties are brown. It is hard, tough, and difficult to powder. It is tasteless, and insoluble in alcohol and ether. It is insoluble in cold water but it swells up and forms a thick, jelly-like mucilage.- When diffused through a larger amount of water, it yields a ropy liquid. This liquid usually gives a blue color with iodine, show- ing the presence of starch, of which it contains from 5 to 6 per cent. Tragacanth contains about 60 per cent, of a gummy or pectinose body, which yields pectic acid on boiling with water containing i per cent, of HCl, and about 10 per cent, of soluble gum, probably identical with arabin. The characteristic pecti- nous constituent of tragacanth is variously known as tragacan- thin, adracanthin, or bassorin, and is believed to have the 360 MEDICAL CHEMISTRY. composition QjHjoOio- Metarabin is another gum, found in the roots of carrots, beets, etc. It is insoluble in water and is converted into arabin by treatment with dilute alkalies. Cerasin is the insoluble part of the gum of the cherry-tree and peach-tree. By long-continued boiling with water it yields arabin. Pectin is obtained by the action of natural ferments on pectose, an insoluble body existing in unripe fruits. It exists ready formed in Irish moss and some other mosses. It is soluble in water, the solution gelatinizing on adding either acids or alkalies. It is precipitated by alcohol. By treating with bases, pectin yields pectates, which on addition of hydrochloric acid give insoluble pectic acid. Algin is obtained from various seaweeds. It is soluble in cold water, forming viscid solutions which do not gelatinize on cool- ing. Vegetable Mucilage occurs in linseed, marshmallow, quince-seed, elm bark, etc. Very little is known of the compo- sition of these bodies. ETHERS. 609. A simple ether is an oxide of a hydrocarbon radical. If we substitute a bivalent oxygen atom for one hydrogen atom in each of two similar hydrocarbon molecules, we have a simple ether, thus: — CjHg j CjHs ) If we suppose that in a molecule of water, HOH, we remove both H atoms, and put hydrocarbon or alcohol radicals in their places, we have an ether. When the two radicals are alike it is a simple ether, and when unlike it is a mixed ether. Examples of simple ethers — CHj — O — CH3. Methyl ether or Methyl oxide. C,H5-0-C,H,. Ethyl ether or Ethyl oxide. Example of a mixed ether — CHg — O — C2Hg. Methyl-ethyl ether. Haloid ethers, so-called, are the addition or substitution products containing one of the halogen elements ; as — CjHjBr or CHjCl. ETHERS. 361 Compound ethers are formed by replacing one of the hydrogen atoms in a molecule of water by a hydrocarbon radical, and the other by an acid radical ; as — C2H5 — O — C2H3O. Ethyl acetate. Formation of Ethers. — Ethers may be formed by the dehydrating action of H2SO4 upon the corresponding alcohols. 2QH5OH - HP = (C,H5),0. They may also be formed by the reaction of the chloride or iodide of an alcohol radical, upon an alcohol in which the alco- holic hydrogen has been replaced hy a metal — C-HsONa + CjHJ = C^UfiC^K^ + NaT. Sodium Ethyl Ethyl ether. Sodium ethylate. iodide. iodide. QHsONa + CH3I = CHgOCjH^ + Nal. Sod. ethylate. Methyl Methyl-ethyl ether, iodide. The compound ethers may be formed by warming a mixture of the alcohol and the aeid, or alkaline salt of the acid, with sulphuric acid — CjH.OH + NaqHsOj + H^SO^ = Ethyl Sod. acetate, alcohol. CjHs — O — C2H3O + HNaSO^ + H^O. Acetic ether or Ethyl acetate. Or by the following reaction : — QHjI + KCHjO = C^Hj — O — CHO + KI. - Ethyl Potass. Ethyl formate. Potass, iodide. formate. iodide. The ethers are abundantly produced by both plant and animal life. Many of the essential oils contain compound ethers. The odors of flowers, of ripening fruits, of perfumes, and the pecu- liar bouquet of the various alcoholic beverages are principally made up of compound ethers. The most important class of compound ethers are the fixed animal and vegeta'ble oils. 610. Ethers of the Paraffin Series. — Methyl oxide — Methyl ether, CH3 — O — CH3 — is a colorless gas of an ethereal odor, soluble in water, alcohol, and H2SO4. It is pre- pared by the action of HjSOi upon methyl alcohol. It liquefies at -36° C. ( -32.8° F.). 31 362 MEDICAL CHEMISTRY. 611. Ethyl ether — Ethyl oxide — Sulphuric ether — ^ther (U. S. P.) — is prepared by heating a mixture of ethyl alcohol and gulphuric acid, and distilling over the resulting ether. About 10 parts by volume of commercial alcohol and 12 parts of strong sulphuric acid are introduced into the retort, which is provided with two openings. Into one of these a thermometer is placed, while into the other is inserted a funnel tube. The retort is heated until the thermometer marks 130° C. (266° F.). Alcohol is now allowed to run in slowly through the funnel tube, while the temperature is kept between 130° and 140° C. (266° to 284° F.). The ether distils off with part of the water pro- duced, and a small quantity of alcohol and sulphurous oxide. The crude ether floats upon the water as a distinct layer. To obtain it in a pure state, it is washed with dilute soda solution, dried over quicklime or calcium chloride, and redistilled by the heat of a water bath. This product is called " washed ether." It still contains some water and alcohol, and for anaesthetic purposes must be again purified by the same process. By the above process, a small quantity of sulphuric acid may be made to etherize a very large quantit/'of alcohol. The action takes place in two stages, as follows : — CjH,OH + H2SO4 = (CjHJHSOj + HjO. Alcohol. Ethylsulphuric acid. QHjHSO, + QH^OH = C,H,-0~C^U, + H^SO,. Elher. Properties. — Pure ether is a very volatile, mobile, highly refracting, colorless liquid, possessing a characteristic odor and' burning taste. Sp. gr. 0.725 to 0.728 at 15° C. (59° F.). It boils at 37° C. (98.6° F.). It is soluble in ten volumes of water, and in all proportions in alcohol, chloroform, benzene, fixed and volatile oils. It is highly inflammable, burning with a luminous flame ; in handling it, therefore, care should be taken not to come near a flame. It dissolves resins, oils, and many other organic bodies. It dissolves iodine, bromine, corrosive sublimate, sulphur, and phosphorus. For anresthetic purposes, it should not afl^ect blue litmus ; it should leave no residue when a quantity is evaporated on a watch glass, nor should it leave a foreign odor ; it should boil in a test tube when the latter is held in the hand, and it should not impart a blue color to ignited copper sulphate (absence of water). Twenty c.c. when shaken with an equal volume of water previously saturated with ether, COMPOUND ETHERS. 363 should not lose more than .2 c.c. in volume. A small quantity of alcohol, less than 4 per cent., is not a serious objection. It is used in preparing spirit of ether, and spirit of compound ether, or Hoffman's anodyne. Ether is largely used in medicine as an anaesthetic, and is em- ployed by inhalation, or, for local anaesthesia, is sprayed upon the part. When taken in overdoses it causes death. Patients who have taken an overdose may usually be resuscitated by arti- ficial respiration, or by the use of the induced current applied upon the neck and epigastrium. In cases of death, the odor of ether usually lingers upon the clothing and in the lungs for several hours. COMPOUND ETHERS, or ESTERS. 612. Compound ethers correspond in structure with the salts of the metals, in which the metal, or compound radical, is replaced by a hydrocarbon radical. Thus, sodium acetate corresponds with ethyl acetate — Na— O— CjHjO and C.,H,— O— CjHjO. Sod, acetate. Ethyl acetate. Compound ethers may be formed in some cases by the direct action of the acid upon the corresponding alcohol — HjSOi -f- 2 C2H5— OH = (QH^ljSO, + HjO. Sulphuric Ethyl Ethyl Water, acid. alcohol. sulphate. In most cases it is necessary to use some sulphuric acid to take up the water formed by the reaction, in order to form the ethers, and for the same reason we employ the solid salt of the acid we wish to combine with the alcohol. A second method of preparing these ethers is by first forming a haloid ether with the alcohol radical, and causing a double reaction between this and a silver salt of the acid. AgNO, + CjHsCl = CjHj ^ O — NOj + AgCl. Silver Ethyl Ethyl nitrate. Silver nitrate. chloride. chloride. All compound ethers, when treated with a strong alkali, give up their acids to the alkali, and set free the alcohol, or hydrox- ide of the hydrocarbon radical. This decomposition is termed saponification, by whatever means it is accomplished. There are a large number of these compounds known, but a few only are met with in medicine. 364 MEDICAL CHEMISTRY. 613. Ethyl acetate— .ffither aceticus (U. S. P.)— Acetic Ether (C2H5 — O — C2H3O) — is prepared by distilling a mixture of strong sulphuric acid, alcohol, and sodium acetate. The dis- tillate is washed with a solution of calcium chloride and milk of lime, decanted, dried over calcium chloride, and finally redis- tilled. Acetic ether is a colorless, limpid liquid, boiling at 74° C. (165° F.) and possessing a pleasant, fruity odor. It dissolves in about 8 parts of water, the water becoming acid from decomposi- tion of a part of the ether into acetic acid and alcohol. It is misci- ble with methyl and ethyl alcohol and with ether in all proportions. It is a good solvent for the essential oils, resins, morphine, gun cotton, and most other substances soluble in ether. The refreshing smell of hock-vinegar and some old wines is due to the presence of acetic ether. The ether in inflammable, burning with a bluish-yellow flame and acetous odor. 614. Ethyl Nitrite, or Nitrous Ether(C2H5— O— NO), is a mobile liquid, boiling at 16.5° C. (61° F.). It has a sp. gr. of 0.947, and is insoluble in water, but freely soluble in alcohol. It is prepared by distilling a mixture of alcohol, potassium nitrite, and sulphuric acid, or by gradually heating a mixture of equal parts of alcohol and strong nitric acid until it begins to boil ; then remove the heat and allow it to distil slowly. It is purified as described above for the other ethers. Spirit of Nitrous Ether — Spiritus .ffitheris Nitrosi (U. S. P) — Sweet Spirit of Nitre — is a mixture of ethyl nitrite, ethyl alcohol, aldehyde, and acetic ether. It is prepared by adding to 770 grms. of sodium nitrite, dissolved in a liter of water, 550 c.c. of alcohol ; the mixture is cooled by ice water, and 520 grms. of H2SO4, diluted with 1000 c.c. of water, added slowly through a funnel tube. The resulting ether is then slowly distilled over. The distillate is washed with ice water, to remove alcohol, and then with a solution of sodium carbonate, and finally dried with potassium carbonate. It is then mixed with 21 times its weight of deodorized alcohol. Spirit of nitrous ether is a clear, mobile, volatile, pale yellow, inflammable liquid, having a fragrant etherial odor and sharp, burning taste. The sp. gr. is about 0.836 to 0.842 at 15° C. (59° F.). It should boil at about 65° C. (149° F.). When 5 c.c. of the liquid is placed in a nitrometer with 10 c.c. of a 16 per cent, solution of potassium iodide, and then 10 c.c. of a normal solution of H2SO4 added, it should give off not less than 55 c.c. of NA- (U. S. P. test.) COMPOUND ETHERS. 365 615. Ethyl Sulphates.— 'There are two sulphates of ethyl, the one neutral and the other acid, corresponding to the neutral and acid sulphates. When H2SO4 acts upon an excess of alcohol we have the following reaction : — CjHjOH + HjSOi = CjHjXg^ -I- H O Ethyl alcohol. Sulphuric HO / * ' ' " acid. Ethyl-sulphuric Water, acid. This reaction is the first step in the manufacture of ether. On heating with alcohol this compound breaks up into ether and sulphuric acid. Ethyl Sulphate, (€2115)2504, is a heavy, oily, yellow liquid, prepared by mixing in a retort equal volumes of alcohol and sulphuric acid, and after 24 hours distilling off the contents of the retort at about 150° C. to 160° C. (302° to 320° F.). This oily liquid is known as heavy oil of wine. When mixed with an equal volume of ether it forms the Oleum .^the- rium of the U. S. P. It is used in making the compound spirit of ether. /NH2. 616. Ethyl Carbamate— Urethane—CjHs—O—C = O This compound ether is formed by acting upon ethyl carbonate with ammonia at 100° C. (2i2°F.). Ethyl carbonate is prepared by treating silver carbonate with ethyl iodide (C2H5I). {C,B,),CO, + NH3 = C2H5 - O-CO-NH2 + HOC2H5. Or, by the action of urea nitrate upon alcohol at a temperature of 120° to 130° C. (248° to 266° F.). CO(NH2)2HN03 + C2H5OH = NH4NO3 + NHjCO— O— C2H5. Urea nitrate. Ethyl alcohol. Am. nitrate. Ethyl carbamate. The resulting urethane is extracted with ether and recrystallized. Urethane occurs as odorless, colorless, columnar, or tabular crystals, with a taste resembling nitre. It melts at 47° C. (ii6.6°- F.)and distils at 180° C. (356 F.). It is readily soluble in water and most other media. Tests. — Heated with HjSO, it gives off CO2 and traces of al- cohol. Heated with KOH it gives off ammonia. If i grm. be dissolved in 10 c.c. of water, and 2 grms. of sodium carbonate and a few granules of iodine added, and the mixture gently warmed, iodoform separates on cooling. Urethane is used in medicine as a hypnotic in doses of i to 2 grammes. Somnal is a solution of chloral and urethane in alcohol. Ethyl 366 MEDICAL CHEMISTRY. benzoate, valerianate, butyrate, nitrite, nitrate, etc., are prepared very much in the same way as the above ethers, substituting the salts of the acids here indicated for the sodium acetate in Art. 593. 617. Amyl Acetate (C5H11 — O— C2H3O) is prepared by dis- tilling a mixture of amyl alcohol, sulphuric acid, and sodium acetate. It has a pleasant, ethereal odor. It is manufactured on a considerable scale for use as a flavor- ing agent for confectioners. 618. Amyl Nitrite (C5H11 — O — NO) is prepared by passing nitrogen trioxide, N2O3, into amyl alcohol. It is a colorless or slightly yellow liquid, and possesses the choking smell of amyl compounds generally. It boils at 96°C. to99°C. (205° to 2io°F.), specific gravity. 872 to .874. Its vapor, when inhaled, produces at first a sense of fulness in the head and dizziness; then flushing of the face, increased heart action, and lowering of the blood pressure and temperature. It may contain as impurities nitric acid, amyl nitrate, amyl valerianate, and hydrocyanic acid. It is almost insoluble in water but mixes in all proportions in ether and alcohol. It is very volatile even at low temperatures, and is inflammable. The method of assaying amyl nitrite is the same as that above described for ethyl nitrite; 0.26 grms. should yield about 40 c.c. of gas. 619. Salol— Phenyl Salicylate, CeHs — O — QHA — is prepared by heating a mixture of sodium-phenol, sodium sali- cylate, and phosphorus oxychloride. The reaction is as follows : 2CjH50Na + 2CeH40HCOONa -|- POCl = 3NaCI + NaPOj -f CjHjOHC- O-O-QHj. Sod. phenol. Sod. salicylate. Phenyl salicylate. Another method is to heat salicylic acid in a flask to 220° to 23o°C. (428° to 446° F.) in an atmosphere of inert gas, as COj, when it loses water and CO2 and is converted into salol. Salicylic acid. Phenyl salicylate. This ether is found in the market as a white, crystalline powder, almost insoluble in water, having a faint aromatic odor and a slightly salty taste. It is soluble in ether, alcohol, benzene and fatty oils. It melts to a colorless, oily liquid at 43° C.(iio° F.). It is not a very stable compound, and breaks up easily into car- bolic and salicylic acids. With fixed alkalies it breaks up into a salicylate and alkali phenol. This change takes place with bile COMPOUND ETHERS. 367 in the duodenum when taken internally. It is a patented article introduced into medicine as a remedy for rheumatism, and as an antiseptic for internal administration. 620. Salophen — Para-amido-phenol Salicylate — o —OH /H I CeHi-CiHiOj N— COOH CeH — 0-C-CeH,~0H, H— N— C— CH3 O may be regarded as salol in which an atom of hydrogen in the phe- nyl group has been replaced by the univalent group NHCOCH3. Salophen occurs in minute white, crystalline scales, almost en- tirely insoluble in water, and free from odor and taste. It is freely soluble in alcohol and ether. The alcoholic solution gives aviolet coloration with FCaCle similar to salicylic acid. It melts at 187° C. (368.6° F.). Like salol, it splits up in the body, and is excreted as salicyluric acid, and para-phenol compounds. It is comparatively harmless. Salol-camphor is prepared by fusing a mixture of 3 parts salol and 2 parts camphor. It is a colorless, oily liquid, soluble in ether, chloroform, and oils. 621. Fruit Essences. — Many of the compound ethers are found in the essential oilsof plants and fruits. Salicylic aldehyde or ( OH salicylous acid, CeHj -j (-.qjt is the essential oil of meadow-sweet, and may be prepared artificially by the oxidation of salicin. Methyl salicylate, CeH^ -j pooptj composes almost entirely oil of wintergreen (Ol. Gaultherise, U. S. P.), and oil of birch (01. Betulse Volatile, U. S. P.). This last may be prepared arti- ficially by heating chloroform and sodium phenol. 622. Artificial Fruit Flavors. -"-These flavoring extracts have come into use extensively in recent years, and are manufac- tured largely from various mixtures of compound ethers, organic acids, and glycerin. The following formulae will give some idea of the character of these mixtures : Pine Apple consists of chloroform, one part ; aldehyde, one part ; ethyl butyrate, five parts ; amyl butyrate, ten parts ; and glycerin, three parts. Strawberry, of ethyl nitrate, one part ; ethyl acetate, five parts ; ethyl formate, one part ; ethyl butyrate, five parts ; methyl salicylate, one part ; amyl acetate, three parts ; amyl butyrate, two parts ; glycerin, two parts. Pear, of ethyl acetate, five parts ; amyl acetate, ten parts ; benzoic acid, one part, and gly- cerin, ten parts. 368 MEDICAL CHEMISTRY. The ethers are to be dissolved in pure alcohol (specific gravity .83), and the numbers given indicate the quantity to be added to 100 parts of alcohol by measure. These mixtures, when taken in large quantities, produce deleterious effects ; but as the quan- tities actually used are very small, they probably produce no appre- ciable effects. Besides the above mentioned and many other " fruit essences," these ethers are also extensively employed to improve the flavor of poor wines, and to fraudulently imitate wines, brandy, rum, whiskies, etc. 623. Ethers of Glycerin, orGlycerids. — Asglyceryl, C3H5, or the radical of glycerin, is a valent radical, it can and usually does, unite with three molecules of a monobasic acid. The compound ethers of glyceryl and the acids of the first or paraffin series compose most of the natural fixed oils and fats. For this reason the acids formed from this series are called collectively the fatty acids. The trinitrate of glyceryl has already been described. The natural fixed oils and fats are composed of mixtures, in most cases, of two or more of these glycerids. The principal of these glycerids found in natural fats are given below in tabular form. Name. Formula, Occurrence. Tributyrin, C3H5(OC4H,0)3, Butter. Trivalerin, C3H5(OC5H50)3, Solid Excrement. Tricaproin, C3H5(OC5Hj,0)3, f Butter. Tricaprylm, CsH^^OCjHisO^j, \ Faeces. Tricaprin, C3H3(OCi„H,,0)3, Triolein, C,H5(OC,8H330j3, Oils (Olive oil), Tripalmatin, CjHj^OCigHjiOJj, Oils and Fats (Palm oil). Tristearin, C3H5(OCi8H350)5, Animal Fats (Tallow). NATURAL FATS AND FIXED OILS. 624. Almost all the fats and fixed oils are compound ethers of glyceryl, C3H5'". They are found in both the animal and vege- table kingdoms. Some are liquid, while others are solid.. Some oils remain permanent in the air, like olive oil, while others oxidize and thicken; like linseed and poppy oil. These latter are called siccative, or drying oils. The : fats are insoluble in water, difficultly soluble in alcohol, but soluble. in ether, petro- leum naphtha, and carbon disulphid. The composition of natural oils has been partially considered while speaking of the fatty acids. So far as known, no fat consists purely of.one sub- stance, but of a mixture of oleate, palmitate, and stearate.of the triad radical, glyceryl, C3H5. NATURAL FATS AND FIXED OILS. 369 These fats are decomposed by heat ; acrolein being one of the products. Stearin, or Stearine, C3H5(CigH3502)s, is found in the more solid fats. It may be separated from the other principles, by melting tallow with turpentine, when the stearin remains in solu- tion, while the olein and palraitin are precipitated. By adding water to this liquid, the stearin may be separated. It fuses at 71° C. (i6o° F.), and solidifies again at 50° C. (122° F.). Palmitin, C3H5(Ci6H3i02)3, is the chief constituent of mutton fat, lard, and human fat. It is more soluble in alcohol and ether than stearin. It crystallizes in fine needles, and its melting point is at 46° C. (115° F.). Olein, C3H5(CigH3302)3, is the fluid constituent of most fats and oils. When pure, it is a colorless fluid, becoming yellow on exposure to the air. It may be obtained from olive oil by treat- ing it with cold alcohol, cooling the solution to 0° C. (32° F.), to separate the palmitin, and adding water to the alcoholic solu- tion to precipitate the olein. Olein is more abundant in vege- table than in animal oils. When treated with hot alkalies or superheated steam, the fats are saponified. Most fats decompose slowly in contact with air, and become rancid. In the process of digestion they are partially saponified and then emulsified; i. e., broken up into minute drops. The active agents in this change are the bile and pan- creatic secretion. The emulsification and absorption of partially saponified fats takes place with greater ease than with pure fat ; hence, a slightly rancid oil is more easily assimilated than a fresh one. The sources of fat in the human body are, ist, the fat taken as food ; 2d, the decomposition of proteids ; 3d, the carbohydrates, a portion of which are converted into fat. 625. Fixed or Non-volatile Oils. — These oils are termed '"fixed" to distinguish them from the volatile or essential oils described in another place. When rubbed upon paper they render it translucent, the spot remaining more or less permanent. They are, when pure, nearly tasteless and odorless, unctuous to the touch, insoluble, and float upon water. Some of them absorb oxygen when exposed to the air, and become thick and gummy. These are called drying or siccative oils. The fixed oils are usually obtained by pressure with or without the aid of heat. 626. Olive oil — oleum olivae (U. S. P.) — is a well-known oil expressed from the fruit of the olive tree. It is a yellow or green- 32 37° MEDICAL CHEMISTRY. ish-yellow color, almost odorless, of a bland, sweetish taste. The finest grades have a greenish tinge, and are prepared by submitting the fruit to cold pressure. Olive oil is frequently adulterated, chiefly with poppy oil, sesame oil, cotton seed oil, and peanut oil. The method of detection of adulterations will be seen by reference to the table on p. 377. Thesp. gr. of olive oil is .915 to .918. It is very sparingly soluble in alcohol, but readily soluble in ether, chloroform, or carbon disulphide. When cooled to about 10° C. (50° F.) it begins to deposit crystalline particles, and at 0° C. (32° F.) it forms a white, granular mass. 627. Almond oil — oleum amygdalae expressum (U. S. P.) — is a fixed oil expressed from bitter or sweet almonds, a clear pale, straw-color, or colorless oil, almost inodorous and having a mild, sweet taste. The pure oil has no odor of bitter almonds. Sp. gr. is from .915 to .920. It is slightly soluble in alcohol, and it is readily soluble in ether and chloroform. If 2 c.c. of the oil be shaken with i c.c. of fuming nitric acid and i c.c. of water, a white or reddish-brown mixture should be formed, which should separate, on standing some hours, into a white, solid mass and scarcely colored liquid. 628. Earth nut or peanut oil — arachis oil — is obtained from the nuts oi Arachis hypogea, the oil being chiefly expressed in France. The nut contains about 45 per cent, of the oil. It is of a pale greenish-yellow color, of a distinctly nutty flavor and smell, and is used very largely in the adulteration of olive oil, lard oil, and other oils. 629. Cotton seed oil— oleum gossipii seminis (U. S. P.) — is a fixed oil expressed from the seeds of Gossipium herbaceum, or the cotton plant, and subsequently purified. It is a pale yellow oil without odor, and having a bland, nut-like taste. Its sp. gr. is 0.920 to 0.930. It is largely employed as a substitute for, or an adulterant of, olive oil. It is largely used as a substitute for lard in cooking, in the manufacture of butterine and soap, and for adulterating other oils. 630. Sesamfe or teel oil — benne oil — oleum sesami (U. S. P.) — is a fixed oil expressed from the seeds of Sesamum indicum. It is a yellow, inodorous, and bland oil resembling cotton seed oil, and used for the same purposes. It is an im- perfect drying oil, and does not readily turn rancid. Its behavior with reagents will be seen by reference to the table. 631. Cod-liver oil — oleum morrhuae (U. S. P.) — is a fixed oil obtained from the fresh livers of the cod, Gadus motrhucB. It is obtained by pressure, either with or without the aid of heat. NATURAL FATS AND FIXED OILS. 37I Several qualities of cod-liver oil are recognized in commerce : a pale oil of a straw yellow color, a pale brown oil of inferior qnality, also used in medicine, and a dark brown variety obtained by roughly boiling down the livers and known as tanner's oil. When fresh, the best grades of oil are almost colorless and limpid, with slight odor and taste and a faint acid reaction. On standing, the fishy taste and odor, as well as the acid reaction, increase. Cod-liver oil consists essentially of several glycerids, the chief one being olein, with variable quantities of myristin, palmatin, stearin, with small quantities of cholesterin and free fatty acids. Cod-liver oil contains traces of iodine and sometimes bromine, but the form' in which these elements exists is unknown. A peculiar acid called gaduic acid, and another substance called gadium, and two alkaloids, acelin and tnorrhuin, have been found. To which of these substances cod-liver oil owes its value as a therapeutic agent, is still a matter of doubt. The property which is probably its chief recommendation for its use, is the facility with which it is . digested or assimilated. This characteristic may be due to the traces of biliary compounds, which are nearly always present. It may in part be due to the readiness with which cod-liver oil becomes rancid or saponifies, as slightly rancid oils are more easily emulsified than neutral oils, and as it very easily saponifies, this would favor its emulsification and absorption. Cod liver oil is seldom adulterated. 632. Linseed oil — flaxseed oil — oleum lini (U. S. P.). — It is a dark-yellow fixed oil, expressed from ground linseed without the use of heat. Ii has a characteristic disagreeable odor and taste. Linseed oil consists of about 80 per cent, of linolein with smaller quantities of olein, myristin, and palmitin. Linolein is a glycerid of linoleic acid. The drying property of linseed oil is due to the presence of linolein, which absorbs oxygen from the air and is converted into a gummy mass resembling rtsin. The varieties of linseed oil recognized in commerce are raw, refined, artists', and .boiled. The tendency of linseed oil to oxidize is much increased by heating it to a high temperature, while passing a current of air through and over the oil, and sub- sequently increasing the temperature until the oil begins to effer- vesce. The temperature employed is from 130°' C. (266° F.) upward. This process is termed boiling the oil. The oil thus treated is called boiled oil. By continued boiling the oil becomes very thick and may be drawn out into elastic threads. This process is used in the manufacture of printing ink. By 372 MEDICAL CHEMISTRY. adding litharge, ferric oxide, manganese oxide to the oil during the boiling process, the oxidation and consequent drying properties of the oil are increased. The salts of lead and manganese are most employed in the manufacture of " driers " for linseed oil. 633. Castor oil — oleum ricini (U.S.P.) — is usually obtained by the extraction of the oil by expression of the seeds of Ricinus communis, which' contain nearly one-half their 'weight of oil. If not clear, the oil is treated with animal charcoal or magnesia, and filtered. It is a thick, viscid, transparent, colorless or greenish-yellow liquid, having a faint odor and disagreeable taste. At a low temperature it thickens and deposits white granules, and at about — 18° C. (0° F.) it solidifies. Castor oil differs from most other fixed oils by its density, viscosity, and its ready solubility in alcohol and insolubility in naphtha. Its sp. gr. is .950 to .970. Nitric acid attacks it energetically and converts it into suberic acid. Ammonia precipitates from it a crystalline solid. It is used in medicine as a laxative. 634. Palm oil has a reddish-yellow to a brown color, and varies in consistency from that of soft lard to that of tallow. As met with in commerce, it is frequently contaminated with water and solid impurities and is more or less rancid. 635. Cacao butter — oleum theobromatis— is a fixed oil expressed from the seeds of Theobroiha cacao. It is a yellowish- white solid, having a faint, agreeable odor and a bland, chocolate- like taste. Sp. gr. is from .970 to .980. It is readily soluble in chloroform and ether, and is soluble in 120 parts of boiling absolute alcohol or 100 parts of cold alcohol. It does not easily become rancid. Its fusing point is between 30° and 33° C. (86° F.). It is a brittle solid at ordinary temperatures. 636. Croton oil— oleum tiglii — is expressed from the seeds of Croton tiglium. It is a pale yellow or brownish-yellow, some- what viscid, and slightly fluorescent liquid, having a slight fatty odor and a mild, oily, afterward acrid and burning taste. Croton oil contains, besides the glycerids of oleic, crotonic, and fatty acids, a peculiar principle called crotonol, to which the oil owes its vesicating properties. When applied to the skin it produces a pustular eruption, and when taken internally is a drastic cathartic. The oil has an acid reaction to litmus paper. It is soluble in alcohol, its solubility increasing with age. It is very soluble in ether, alcohol, chloroform, and in the fixed and volatile oils. 637. Neat's foot oil is obtained by the action of boiling water upon the feet of cattle, horses, sheep, and other animals. It NATURAL FATS AND FIXED OILS. 373 is a Straw yellow, odorless, nearly tasteless liquid. It is not readily prone to rancidity. 638. Lard oil — oleum adipis (U.S. P.) — is extracted from lard at a low temperature. It is a light yellow, transparent oil, used in cooking, soap making, and in artificial butter, or butter- ine. It is very frequently adulterated, principally with cotton seed and other seed oils, rape oil, earth nut, etc. Tallow is the fat of the ox and sheep, obtained by gentle heat. It is a white or yellowish-white brittle solid, used largely in the manufacture of soap and candles. Tallow oil, or oleo oil, is obtained by expression with gentle heat, the more liquid portion running out and the more solid portion remaining behind in the press. This oil is especially prepared for the manufacture of oleomargarine . 639. Butter consists of a mixture of stearin, palmitin, and olein, not soluble in water, and the glycerids of butyric, cap- roic, caprylic, and capric acids. These last acids are soluble and volatile. Oleomargarine, butterine, suine, etc., are artificial mix- tures of butter with foreign fats, made to imitate butter. The principal foreign fats employed are lard, beef oil, cotton seed, sesam6, and similar oils. The usual method of manufacture is to melt the foreign fats, deodorize them, wl^en necessary, with nitric acid, then either to mix them with genuine butter, or churn them with milk. The mixture usually has a melting point above or below that of genuine butter. Melting points of various fats : — Butterine, 31.3° C. (88.5° F.). Cacao butter, 34.9° C. (94.7° F.). Butter (average), 35.8° C. (96.6° F.). Beef dripping, 43.8°C. (Mi.l° F ' Veal dripping, 47.7° C. ( 1 18° F.) Beef dripping, 43.8°C. (Mi.l° F.). - - ' ' ' ^ "a(ii8°F.). Lard, ' ' 42° C. to 45° C. (107.5° to "3° F-)- Mutton fat, 50° C. to 51° C. (122° to 123.8° F.). Tallow, 53° C. (127.4° F.). A low melting point generally indicates butterine, or vegetable oils, while a high one indicates the presence of animal fats. The detection of foreign substances in butter is a matter of considerable importance, owing to the fact that certain countries have laws prohibiting the sale of artificial butter, or at least restricting its sale. The modern butter substitutes are close imitations of natural butter, and can only be detected by chemicaK processes depend- ent upon the difference in chemical composition of butter fat 374 MEDICAL CHEMISTRY. and other animal or vegetable oils. The butter fat is saponi- fied with a solution of KOH, the soap thus produced is again decomposed with a mineral acid and the fatty acids are separated. Stearic, oleic, and palmitic acids are insoluble in water, while butyric acid and certain others are soluble. Butter fat when thus treated yields from 5 to 8 per cent, of soluble acids and from 85.5 to 88,5 per cent, of insoluble acids. The sura of the insoluble and soluble fatty acids should always amount to fully 94 per cent, of the fat taken. The other fats and oils, when saponified by this method, yield mere traces of the volatile or sbluble fatty acids, and from 95.5 to 97.7 per cent, of insoluble acids. These variations are taken advantage of for the identifi- cation of genuine butter or the detection of mixtures. In actual practice 2.5 grms. of the purified butter fat is taken and saponified with KOH, the soap decomposed with dilute HjSOi, and the mixture submitted to distillation. The soluble or vola- tile acids distil off and are estimated by titration with a standard alkali. From the amount of alkali required to neutralize the volatile acids, the quantity or percentage may be calculated. The insoluble acids remain behind in the distilling flask. If it be desired to do so they may be filtered out and weighed. Another method that is sometimes employed for the detection of adulter- ation in butter is the amount of alkali, KOH, required to saponify a known weight of butter. This is known as, its saponifying equivalent. It is determined by adding to a known weight of the purified butter fat an excess of standard solution of KOH, and heating until saponification is complete. The excess of KOH is then estimated by a standard acid. The difference between that added, and the free alkali remaining, gives that in com- bination with the fatty acids of the butter, or the saponifying equivalent. The amount of alkali required for the saponification of butter is much greater than that of most other oils. Another method which is depended upon to distinguish butter from other fats or oils, is the amount of iodine or bromine that a given weight of butter fat will absorb under prescribed conditions. For particulars concerning these various processes we must refer the student to special works on the subject. 640. Identification of Fixed Oils. — Various methods have been devised for the identification of fixed oils and fats. Some of these depend upon the separation of the fat into its con- stituents, and the quantitative estimation of these constituents. These processes are rendered necessary because of the extensive adulteration to which commercial oils and fats are subjected. NATURAL FATS AND FIXED OILS. 375 Some of these processes are designed especially for the detec- tion of the falsification of butter. Otliers are applicable only to the commercial oils other than butter. One of the first characteristics of oil is its sp. gr., which is usually determined by the use of the sp. gr. flask, the method of using which has been described in Part I. In the first column of the table, P^gs 377i will be found the sp. gr. of the priticipal oils there mentioned. The liquefying temperature is one characteristic property of oils which is made use of for their identification. These temperatures are given in the third column of said table. Of the chemical methods that are employed for the identification of fixed oils, only the simpler ones can be here described. The rise of temperature which ensues on treating a fixed oil with H2SO4 is the measure of the extent or intensity of the chemical 'reaction between the two. The rise of temperature has been taken advantage of by Maumene for the identification of many of the fixed oils. It is found that with a given oil the rise is fairly uniform. The method of applying the test is as follows; 50 grms. of an oil are weighed into a 4-oz. beaker. The beaker is placed in a cotton-wool nest, to prevent conduction of heat. The temperature is carefully observed. Ten c.c. of concentrated sulphuric acid, of the same temperature as that of the oil, is now allowed to run into it during the space of about one minute, the mixture being constantly stirred with the thern\ometer until no further rise of temperature ensues. The rise of temperature may now be readily observed. In the fourth column of the table are given the changes in temperature of the various oils when the test is carried out according to directions. With some oils, sulphuric acid gives characteristic colorations. The next two columns of the table show the effect produced in placing a drop or two of sulphuric acid in the center of about 20 drops of the oil, and observing the color before and after stirring. The colors produced by different samples of the same kinds of oils are liable to some variations from those indicated in the table. Many of the fixed oils give characteristic color reactions with nitric acid as well as sulphuric acid. The method of applying the test is to agitate together from 3 to 5 c.c. of the oil with I c.c. of nitric acid of sp. gr. 1.32. Heat the two for five min- utes in boiling water and then take it out and observe the color of the oil from time to time for an hour and a half. If the acid be of higher sp. gr. it will be unnecessary to apply the heat. The colors given by this test are to be found in the last column of the table. 376 MEDICAL CHEMISTRY. The elaidin reaction is also a characteristic test for many of the fixed oils. It depends upon the action of nitrous acid upon oleic acid of the oils, by which it is changed into elaidic acid, which is solid at ordinary temperatures. The best method of obtaining this reaction is with the following solution : i c.c. of mercury is dissolved in 12 c.c. of cold con- centrated nitric acid, i c.c. of this freshly made solution is then shaken in a wide-mouth stoppered bottle with 25 c. c. of the oil to be tested, the agitation being kept up at intervals for from one to two hours. When treated in this manner oils con- sisting of nearly pure olein give a solid product of greater or less consistency. Olive oil is remarkable for the firmness of the lemon-yellow elaidin production. The behavior of the more important fixed oils when tested in this manner is as follows: — 641. Elaidin Test. — Behavior of most important fixed oils. ' (a) A solid, hard mass : Olive, almond, arachis, lard, sperm, and sometimes neatsfoot. (^) A buttery consistence : Neatsfoot, mustard, sometimes sperm arachis and rape. (c) A btrttery mass separating from a liquid : Rape, sesame, cotton-seed, cod-liver, seal, whale, and porpoise. (//) Liquid products : Linseed, hempseed, walnut, and other drying oils. 642. Fat in the Human Body. — Fats which occur in the animal body are mixtures of olein, palmitin, and stearin in varying proportions. The normal fat in each animal, or class of animals, is characteristic in its composition. Thus, in the fat of man and the carnivora, palmitin is in excess over the other two. In the fat of herbivora, stearin predominates, and in that of fishes olein The fat of butter, as seen above, contains several other glycerids in addition to these three. The fat .that is accumulated in the animal body during fattening cannot be accounted' for by the fat given as food. A large part of it may come from the con- version of proteids and carbohydrates into fat. The manner in which this conversion takes place has been the subject of consid- erable dispute. The belief now is, however, that both proteids and carbohydrates can give rise to the production of fat in the animal body. The total amount of fat in the human body varies within wide limits, but from 3 to 5 per cent, may be taken as a fair average, It is generally greater in women and children than in men. It is generally greater in middle age than during old age, although sometimes this rule is reversed. The object of the storage of fat in the human body, is to provide a surplus of heat- U., 1-4 a z o CJ a z < CO H Z O « CO .CO o 1 o 8 c:- o bo o bO ■s li u s s o u o ■s i o 2 1 01 i 01 o o 1 1. |i 1 o u o ■g a u 1 u o II 1 c: i i 1 u o c 1. p c S g o =3 (3 1 o OS p. o i o 1 o i £ >> .b s ■a .2 i In o c r 2 3 o a w.So c: g c £ I? >< 1 1 o 1 £ •c s 1' ■g •= n £ P. O If s o 2 1 II 1- •S 1°- Q&gS KgoE s u S S d d 2 U o 6 o OD O U o C3 U o , 1 d o O d d o 1 v5 2 + s o 1 o T o + T 2 o 1 oo 1 o 00 2 o °o CQ o o 4 O h Si; g o d o c i o cn 2 o o o « ■>»■ c> in o 1^ 00 d in o i ■» u o 5v in M C7> o» - O m 0\ ' CTi ffl-J 1? J O id o u 5 1 1 -d' s c o a 3 O H *« 1/1 c 1 1 ■s c a 3 m o o 1 1 ■s" cd h9 3 377 378 MEDICAL CHEMISTRY. producing elements for periods of starvation and disease. It also serves to lubricate the different organs, to give rotundity to the form, and to protect the internal structures from sudden changes of temperature, owing to its non-conductivity of heat. The principal service of the fat in the economy is as a producer of heat and energy, by its oxidation. In wasting diseases and starvation, the fats previously stored up are rapidly consumed to sustain the body. In cold climates, therefore, more fats are de- manded than in temperate or hot climates. When fat is taken in excess of that needed by the body, it is either discharged in the faeces, or it is absorbed and stored up as fat. 643. Soaps. — Soaps are metallic salts of the fatty acids, i. e., oleic, palmitic, and stearic. Those of potassium, sodium, and ammonium are soluble in water, those of the other metals are insoluble. Hard soaps are salts of the fatty acids with sodium ; soft soaps are salts of potassium. Soaps are made from almost any fat, but the best varieties are made from lard, olive, peanut, or palm oils. Cocoanut and palm oil soaps are much used at sea, on account of their property of dissolving in salt water. Castor oil is extensively employed for making transparent toilet soaps, and now very extensively used for soap making. Lard soaps are very white, solid, inodorous, and valuable for toilet use. Ordinary yellow soap is made by saponifying tallow or palm oil with soda. More or less resin is often added, but the use of too large a proportion renders the soap dark. The principal soaps of commerce contain either an excess of uosaponified oil or fatty acid, on the one hand, or an excess of alkali on the other. The alkali may be either as a carbonate ox caustic alkali. Such soaps are said to be alkaline soajjs. Small quantities of foreign substances are frequently added to soaps, as coloring, perfuming, or medicinal agents. Medicated soaps are now sold, which con- tain a considerable proportion of medicinal agents, such as car- l)Qlic, ■salicylic, or cresylic acids, thymol, tar, sulphur, ichthyol, naphthaline, camphor, etc. An excess of glycerin is sometimes added, which is a valuable ingredient in certain soaps. In the manufacture of soap the alkali is either added to the fat previously saponified with superheated steam, or to the free fatty acids. In the first case the glycerin is partially left in the soap, in the second the glycerin has been removed. After the formation of the soap, it is separated from the solution by either evaporating down and allowing it to solidify, or it is precipitated from its solution by the addition of salt. The flaky precipitate is separated, melted, and cast into moulds. ALEOHYDES. 379 White Castile Soap — Sapo (U.S. P.) — is a soda soap made from olive oil. It is strongly alkaline, hard, yet easily cut when fresh, having a faint, peculiar odor free from rancidity, and has .a disagreeable alkaline taste. It is soluble in water and in.alco'hol, more readily with the aid of heat. Soft Soap— Green Soap— Sapo Viridis (U. S. P. '80)— Sapo Mollis (U. S. P. '93) — is a potassifltn soap made from lin- seed oil. It is a soft, unctuous mags of a yellowish- brown color, soluble in about 5 parts of water to a clear liquid. It is also readily soluble in alcohol. Lead Soap — Lead Plaster — Emplastrum Plumbi (U. S. P.) — is a soap prepared by saponifying olive oil with oxide of lead. It is a yellow, white, pliable or tenacious, but not greasy mass, gradually acquiring a brownish color on exposure to the air. It is insoluble in water but is soluble in benzene and chloroform. When a solution of a soluble soap is added to a water containing the heavier metals in solution, an insoluble soap is usually produced. Hard waters usually owe their hardness to the salts of calcium and magnesium. The soaps produced in this case are the insoluble calcium and magnesium soaps. Acids decompose soaps, liberating the fatty acids and forming other salts with the metal. ALDEHYDES. 644. The aldehydes are compounds formed by the oxidation of the primary alcohols. They differ from the corresponding alcohols by having two atoms of hydrogen removed ; thus ethyl alcd^l forms ethyl or acetic aldehyde : — CH3_C^^^ + O = CH3-C = + Hfi. By oxidation aldehydes yield The corresponding acid. It will be observed that, as two atoms of hydrogen lia-ye been jemoved without putting any atoms in their places, aldehydes are unsatu- rated bodies. On this account, they are very liable to undergo changes with reagents. They are especially prone to undergo oxidation to produce acids, and therefore act as strong reducing agents. They can also take up hydrogen, and regenerate the alcohol. They combine with ammonia to form aldehyde am- monias, and with the acid sulphites of the alkalies to form crys- talline compounds. With chlorine and bromine they unite to 380 MEDICAL CHEMISTRY. form chloride or bromide of the oxygenated radical. With HSj, they form sulphaldehydes. 1. CjHjOH + Oj = 2C2H3OOH 2. C2H3OH + HjCnascent) = CjHjOH. 3. C,H,0H + NH3=C,H,/°g^ 4 . CjHjOH + CI2 = CjHjOCl + HCl. 5. CjHjOH + HjS = CjHjSH + Hfi. Preparation. — Formaldehyde and polymeres of this com- pound (glucose, etc.) are formed in growing plants. (See part V.) 2. The aldehydes may be formed artificially by partial oxida- tion of primary alcohols. 2CJH5OH + 02= 2CjHsOH + 2H2O. 3. They may also be prepared by the action of nascent hydro- gen (sodium amalgam) upon the chlorides or anhydrides of the corresponding acids. CjH,OCI + Hj =CjH,OH + HCl. Acetyl chloride. Acetic aldehyde. §h'o)° + ^"» = 2C,H30H + H,0. Acetic anhydride. Acetic aldehyde. 4. By distilling a mixture of the calcium salt of the corres- ponding acid with calcium formate. Ca(CH02)2 + CaCQHp^)^ = Calcium formate. Calcium butyrate. 2CaCO, -j- CjHjOH. Calcium carbonate. Butyric aldehyde. 645. Formaldehyde, CH20H = ^\H^ is produced by the dry distillation of calcium formate, or by the oxidation of methyl alcohol. It is a gas at ordinary temperatures, and on standing it is gradually polymerized into paraformaldehyde, C3H9O3 = 3(CH20H), a crystalline solid. Formaldehyde has been intro- duced into the market, under the name of formalin, as a 40 per cent, solution in water. It is used as an antiseptic. 646. Acetic Aldehyde — Aldehyde, C2H4O — is prepared on a large scale in the manufacture of alcohol, when it distils over with the first of the distillate. Commercial alcohol generally contains traces of aldehyde. It may be prepared by distilling from a retort a mixture of ALDEHYDES. 381 three parts of crystals of potassium dichromate, four parts of sul- phuric acid, twelve parts of water, and four parts of alcohol. The receiver must be placed in a freezing mixture. Manganese dioxide may be used instead of the dichromate. The impure aldehyde thus obtained is treated with dry calcium chloride to remove water, and then mixed with twice its volume of ether, surrounded by a freezing mixture, and saturated with dry ammonia gas. The crystalline aldehyde ammonia thus formed is separated, and distilled with diluted sulphuric acid from a flask or retort, connected with a well-cooled receiver. It may then be freed from water by standing over fused calcium chloride and redistilling. Aldehyde is a colorless, transparent, mobile liquid, boiling at 21° C. (69.8° F.). It has an acrid, suffocating odor, irritat- ing the eyesi It mixes in all proportions with water, alcohol, and ether. It acts as a strong reducing agent. If mixed with a solution of ammoniated silver nitrate, and warmed, the silver is reduced and deposited upon the glass in the form of a mirror. It gives the general reactions of the aldehydes. A general test for the aldehydes is their property of restoring the red color of a solu- tion of fuchsine which has been decolorized with sulphurous acid. The vapor of aldehyde when inhaled produces asphyxia. When taken internally it produces intoxication. When pure aldehyde is left for some time in contact with HCl, SOj, COCI2, or ZnCIj it undergoes a change, forming two polymeric com- pounds known as paraldehyde and metaldehyde. 647. Paraldehyde, (QH3OH),, or CHrCH | cnrCOH/^' is used in medicine as a hypnotic. It is prepared by treating al- dehyde with a very small quantity of HCl or with ZnClj. The tem- perature of the liquid rises and almost complete conversion into paraldehyde takes place. Purification is effected by freezing out and rectifying. Paraldehyde is a clear, colorless liquid, with an etherial odor, and a burning, afterward cooling, taste. Specific gravity, 0.998. Boils at 124° C. (255.2° F.), and congeals to a crystalline mass at 10° C. (50° F.). One part dissolves in ten of water, forming a neutral solution, miscible in all proportions with alcohol and ether. BaCIj and AgNOs solutions should give no precipitate with it (absence of sulphates and chlorides), and it should give no coloration after two hours' contact with a solu- tion of KOH or NaOH (absence of aldehyde). It may be given in doses of 20 to 40 minims. 382 MEDICAL CHEMISTRY. 648. Metaldehyde, (C^HiO),, is formed from aldehyde by HjSOi or HCl gas at a temperature below 0° C. (32° F.). It is a white, crystalline solid, occurring in needles or prisms. When heated, it sublimes without melting at 112° to 115° C. (234° to 239° F.). It is insoluble in water, but soluble in hot alcohol and ether. It has been also used as a hypnotic. 649. Sulphaldehyde, C2H3SH, is prepared by the action of HjS upon aldehyde. It is an oily liquid with a disagreeable odor. When treated with acids it polymerizes like aldehyde, producing a solid thio-paraldehyde, giving physiological effects like those of paraldehyde. Of the large number of aldehydes known, a few occur in natural products of vegetable origin. 650. Benzoic Aldehyde, CeHjCOH, occurs in oil of bitter almond, in which fruit it is prepared by the decomposition of the glucoside, amygdalin, by the ferment emulsin. It is a colorless, pale yellow, oily liquid with characteristic odor. It is prepared artificially from toluene. Cinnamic Aldehyde, CgHjCOH, occurs in the oils of cin- namon and cassia. When oxidized it gives .cinnamic acid. Salicylic Aldehyde, CeHjO.COH, or oil of spir^a (mead- ow sweet), is prepared from salicin by distilling with H2SO4 and KjOrgO^. Cuminic Aldehyde occurs in the oils of cumin, carraway, etc. Vanillic Aldehyde, or Vanillin, C,H,02.C0H, is extracted from the vanilla bean pods. It is now made artificially from coniferin, a glucoside obtained from the pine family. 651. Trichlor-aldehyde, or Chloral, CCU^COH, is alde- hyde in which the three hydrogen atoms of the radical have been replaced by chlorine atoms ; thus : C2H3OH. CjClsOH. It is prepared by passing dry HCl gas into absolute alcohol un- til it is saturated. The liquid separates into two layers. The lower layer is separated and shaken several times with H2SO4, 4nd finally distilled from the acid. It is thus obtained as a col- orless, oily liquid, having a pungent, irritating odor and a bit- ter, acrid, caustic taste. It boils at 94.5° C. (202° F.), sp. gr. 1.502. It is very soluble in water, alcohol, and ether. It dis- solves the halogens, sulphur and phosphorus. It answers to all the general tests of the aldehydes mentioned above. Oxidizing agents convert it into trichlor-acetic acid, C2CI3OOH, a colorless, crystalline solid, soluble in water. Trichlor-acetic acid has been ALDEHYDES. 383 used as a delicate test for albumin in the urine. Chloral is con- verted into chloroform and a formate by the alkaline hydroxides. QCljOH + NaOH = NaCHO, + CHCl,. This reaction is employed to prepare a very pure chloroform for anaesthetic purposes. It unites with water to form chloral hy- drate, CjClsOH.HjO, a colorless, transparent, crystalline solid, having a pungent odor and an acrid taste. It volatilizes slowly at ordinary temperatures, fuses at 57° C. (134 6° F.), and boils at 98° C. (208° F.), with partial decomposition into water and chloral. Chloral hydrate is readily soluble in water. Under the influence of sunlight, potassium chlorate decomposes chloral with violence. Chloral combines with a considerable range of organic sub- stances. When dissolved in alcohol the temperature rises, OH and chloral alchoholate crystallizes out, CCI3CH ^.^ tt Chloral liquefies when triturated with an equal weight of cam- phor, menthol, thymol, or phenol. Action on the Economy.^ — It has been claimed that the action of chloral on the economy is due to the formation of chloroform Snd a formate, by decomposition after absorption, or in the intestine. Such is probably not the case. When taken in an overdose, chloral acts as a poison, 30 grains having proved fatal, although five or six times that amount has been taken by others with no bad eflect. The symptoms of poisoning by chloral are not uniform or very characteristic. Strychnine has been recommended as a physiological antidote. The stomach should be emptied, and stimulants given freely. Dcrath is likely to occur from heart depression. Tests. — Chloral may be detected in the contents of the stomach by rendering them alkaline with KOH, heating on a water bath, and conducting the vapors through a red-hot tube, and then allowing them to bubble through a solution of AgNO,. If chloral is present it decomposes, giving off chloroform, which is decom- posed, in passing through the hot tube, into HCl and free chlorine. The HCl gives a white precipitate of AgCl. The same experi- ment without the addition of KOH, if it gave positive results, would prove the presence of chloroform, and not chloral, in the contents of the stomach. If the use of chloral hydrate be long continued, it induces a chloral habit. 652. Croton Chloral, or Butyl-Chloral, CsHjClsCOH, 384 MEDICAL CHEMISTRY. bears the same relation to butyl alcohol that chloral does to ethyl alcohol. CjHjOH CjH,OH CjCljOH Ethyl alcohol. Aldehyde. Chloral. CjHjOH C4H.OII CjHjCljOH Butyl alcohol. Butyl aldehyde. Tri-chlor butyl aldehyde, or Croton chloral. It is prepared by substituting aldehyde for alcohol in the pre- paration of chloral. It is an oily liquid of pungent odor, boiling at 164° C. (327.2° F.). It combines with water to form croton chloral hydrate, a crystalline solid, used in medicine as a hypnotic. Chloral combines with ammonia to form chloral-ammonia _ /H CCI3 C — OH, a white, crystalline powder, consisting of fine \NH, needles, fusible at 62° to 64° C. (143.6° to 147.2° F.), soluble in water, and easily decomposing when in solution. It has been used as a hypnotic in doses of 15 to 30 grains. Chloral shows a readiness to combine with the compound ammonias, amids, and camphors. Chloral-amid, chloral- formamid, chloral-imid, chloral-menthol, chloral-ure- than, and a number of like compounds, or mixtures, have been introduced and advocated as remedies for various purposes. 653. Hypnal is a crystalline body formed by the action, at ordinary temperatures, of chloral hydrate upon antipyrin in solu- tion. It is a tasteless, odorless body, soluble in 5 or 6 parts of water. It is used as a hypnotic and anodyne. ACETALS. 654. If acetic aldehyde be heated with alcohol for some time, there is a reaction between them, as indicated by the following equation : — CH3 - COH + aC^H^OH =r CH3 " CHqC^I + ^'°- Aldehyde. Alcohol. Acetal. The compound formed, as here indicated, differs from the aldehyde by having the two oxethyl radicals in the place of the oxygen atom, and is a type of a series of compounds known as acetals. KETONES. 385 Acetal is a colorless liquid, sparingly soluble in water, but miscible with alcohol. OCH 655. Methylal, CH Qpjr', is formed by distilling a mixture of MnOj, H2SO4, and CH3OH, collecting and redistilling the product, and freeing from water by standing in contact with dry KjCO,. The reaction is first to oxidize the methyl alcohol to formaldehyde, which reacts upon more CH3OH. CHp + 2CH3OH = CH, °^|^3 ^ HjO. Methylal is a colorless, mobile liquid, with penetrating ethe- real odor, and boiling at 42° C. (107.6° F.). It is soluble in 13 parts of water, and in alcohol, ether, fixed and volatile oils. It should not decolorize potassium permanganate solutions acidified with sulphuric acid. Strong HjSOj decomposes it, but alkalies do not. It has been used as a hypnotic, and as a cerebral sedative. KETONES. 656. These bodies are the first result of the oxidation of second- ary alcohols, i. e., upon an alcohol that contains the group C --.„ •a instead of C --.tt , as in the primary alcohol. The ketones all contain the group CO. The relation of these bodies will be made clear by the following graphic formulae : — f ^^ -wt /-■ TT C* ^ ^^ f^ ^ H— C— O— H + O = C=0 + HjO. C=Hj + O = C=H. + H.O. II II C=H3 C=H3 C=H, C=Hj Isopropyl Di-methyl ketone. Propyl Propyl, alcohol. or acetone. alcohol. aldehyde. In the nomenclature of the ketones, the name is made to contain the names of all the radicals attached to the CO" group. Thus, ethyl-methyl-ketone would express the name of the following : CH3~CH2~CO -CH3. Ketones are distinguished from aldehydes by their behavior with reagents. Nascent hydrogen regenerates the secondary alcohol with 33 386 MEDICAL CHEMISTRY. ketones, and a primary alcohol with aldehydes. Oxidation pro- duces with aldehydes the corresponding acid, while the oxida- tion of ketones splits the molecules with the formation of two acids. 1 P=0 '-— OH C— OH C= -f 0, = = 1 + 1 1 C=Hs H C^Hs Acetic acid. Formic acid. Acetone. 657. Acetone — Acetyl-methylid — Di-methyl Ketone, (CH3)jCO — is formed by dry distillation of the acetates, sugar, tartaric acid, and by a number of other reactions. It is usually obtained by distillation of calcium acetate. 2Ca(CsH30j), = (CH3)2CO + CaCO, + 3H,0 + CaO. Calcium Calcium Calcium acetate. Acetone. carbonate. Water. oxide. Acetone is present in very small quantities in normal urine and blood, but in larger quantity in diabetes mellitus and iii. aceton- uria. It is a transparent, colorless liquid, having a peculiar ethereal odor. It is miscible with alcohol and ether. It is solu- ble in water, but separates oh addition of salts. It shows the aldehyde reaction with fuchsine and sulphurous acid. It is a good solvent for resins, fats, camphor, gun cotton, etc. It is used as a solvent in varnish manufacture. Its specific gravity is 0.7921. It boils at 56° C. (132.8° F.). Chlorine or bromine, in presence of alkalies, convert it into chloroform or bromoform. 658. Sulphur Derivatives of the Hydrocarbons and Alcohols. — As we have seen in inorganic chemistry, sulphur can replace oxygen in many compounds, especially where it acts as a linking atom. Thus corresponding to HjO we have HjS ; to NH4OH, NH4SH ; to H,CO„ H.CS, So in alcohols we may have sulphur take the place of oxygen. These compounds are frequently called Mercaptans (mercuro captum) from their pro- perty of readily taking up mercury. They may be more properly named sulpho-alcohols or thio-alcohols. In the ethers and aldehydes we may have the same substitution of sulphur for oxy- gen, giving rise to sulphides of the hydrocarbon radicals or sulpaldehydes. These compounds, as a class, are generally ill- smelling compounds, and are frequently produced in the putre- factive fermentation of organic substances containing sulphur. KETONES. 387 The following is a list of some of the more important of this class of compounds : — Sulphides of the Hydrocarbon Radicals. Methyl sulphide, (CH3),S Diethyl disulphide, (CjH5)2Sj " disulphide, (C'Hj)jS, " trisulphide, (C,H5),S3 " trisulphide, (CHjjjSj " tetrasulphide, (C2H5),S4 " hydrosulphide, CH3SH " pentasulphide, (QHjj^Ss (methyl mercaptan) Ethyl hydrosulphide, CjHjSH " di-ethyl oxysulphide, (C,- (mercaptan) 115)2802 (ethyl sulphone) Ethyl oxysulphide, (C2H5)2SO, Xanthic acid C2H5OCSSH Ethyl-sulphonic add, C2H5SO2OH Diethyl sulpho-dimethyl-methane, or sulphonal, (CH3l2C(S02CjH5)2. Of these compounds but few have sufficient importance to claim our attention. Compounds similar to the foregoing may be. formed by other radicals than those here mentioned. 659. Mercaptan, CjHjSH, is prepared by distilling calcium sulph-ethylate with potassium hydro-sulphide. CaCCjHsSO^), + 2KnS = CaSOt + KjSO, + 2(c^n^sn). Calcium sulphethylate. Mercaptan. Mercaptan forms the upper layer of the distillate. Mercaptan has a powerful smell of garlic. It is a volatile liquid, sp. gr. .0835. It burns with a blue flame. It is sparingly soluble in water, dissolves in alcohol and ether. It forms, with metallic sodium and potassium, sodium mercaptid, CjHjSNa, which is a crystalline compound soluble in water. Mercuric oxide reacts with mercaptan, evolving heat and forming a crystalline, inod- orous compound, mercuric mercaptid. When a mixture of I molecule of mercaptan with 2 molecules of an aldehyde is treated with dry HCl, a mercaptal is produced which may be regarded as an acetal whose oxygen is replaced by sulphur. If this same reaction is produced with an acetone in place of an aldehyde, a mercaptol is produced, which differs from the mercaptal in that the alcoholic radical is substituted for the re- maining H atom of the methane. The relation of these bodies may be seen by reference to the following graphic formulae : — HX^/OCjHj HXp/SCjHj CHjVp/SCjHs CH,/-^\OC2H5 CHj/^XSC^Hj CHj/'-VSC^Hs. Acetal. Mercaptal. Mercaptol. CH3\p/SOjC2H5 C2H5\„/S02C2H5 C,U,\^/SO^C,H^ CHj/^XSO.CjHj CHj/^xSOjCjHs C2H5/^\S02C2H5. Sulphonal. Trional, Tet-ronal. 388 MEDICAL CHEMISTRY. 660. Ethyl mercaptol, (CH3)jC(SC2H5)2, is produced by the action of dry HCl upon amixiure of acetone and mercaptan, or upon a mixture of sodium-ethyl thio-sulphate and acetone. The liquid gradually becomes turbid and separates into two layers, of which the upper is mercaptol, the lower dilute HCl. Mercaptol is a mobile liquid whose odor is not disagreeable. It boils at 80° C. (i 76° F.). When mercaptol is oxidized by potassium perman- ganate, it is converted into sulphonal or diethyl sulphon-di- methyl-methane, according to the following equation : — Mercaptol. Sulphonal or diethyl-sulphon- dimethyl-methane. 661. Sulphonal is a colorless, inodorous, practically tasteless, crystalline body, melting at 125° C. (257° F.). It is soluble in I'S parts of boiling water and is about 450 of cold. It is freely soluble in hot alcohol and less so in cold. Sulphonal is a very stable body, being unaffected by acids, alkalies, oxidizing agents, bromine, or chlorine. Owing to its insolubility and stability, it does not present many characteristic reactions. Its solutions are neutral to test paper, and are unaffected by barium nitrate or silver nitrate. It should burn away without residue when ignited with free access to air. When sulphonal is heated with potassium cyanide, the odor of mercaptan is evolved, and when the residue is dissolved in water a drop of FejCle gives a red color to the solution. The urine of patients taking consid- erable doses of sulphonal assumes a peculiar reddish-brown color, due to the presence of haematoporphyrin. This substance is most easily detected by the spectroscope. Sulphonal is used in medicine as a hypnotic, and has become official in the pharma- copoeias of several European countries. By oxidation of ethyl mercaptan, ethyl sulphonic acid is formed. aCjHjSH + 30j = aC^H^SO^OH. Ethyl mercaptan. Ethyl sulphonic acid. 662. Sulphonic acids may be formed by acting directly upon unsaturated hydrocarbons with sulphuric acid. H^SO, + Cell. = CjH^SOjOH -f Hfi Sulphuric Benzene. Benzene sulphonic Water. add. acid. H^SO, -f, CeH^CH, = CeH^CHjSOjOH + H^O Toluene. Toluene sulphonic acid. It will be seen by the above reactions that sulphonic acids correspond with the sulphites. KETONES. 389 663. Ortho-phenol sulphonic acid — sozolic acid — or f OH aseptol, CsHj -j „/-) Qri is sometimes employed as a non- poisonous, non-irritating antiseptic. It occurs sometimes in small, deliquescent needles, but generally appears in the form of a heavy, red liquid of a Syrupy consistency. It has an astringent taste and an odor resembling that of phenol. It is freely soluble in water, alcohol, and glycerin. It has been employed as an anti- septic, both internally and externally. A calcium salt of beta-naphthol sulphonate has recently been introduced as an antiseptic under the name of asaprol, Ca(C]oH5S020H)2. It occurs in acicular crystals, readily soluble in water and alcohol. It has been used internally in doses of from 15 to 60 grs. 664. Saccharin, or benzoil-sulphonic imide, CeHi- COSOjNHj, has been introduced as a sweettning agent. Its sweetening power is 200 to 300 times that of sugar. The sub- stance is usually prepared from toluene sulphonic acid. It is a white powder, with an intense sweet taste and a fine almond odor. It is slightly soluble in water, forming a feebly acid liquid. It is more soluble in alcohol, glycerin, ammonia water, or in a solution of sodium bicarbonate. Saccharin has been largely recommended as a sweetening agent for use by diabetics, to avoid the use of sugar. It has, however, proven unsuitable for this purpose, owing to its disturbing effects upon the digestion. Owing to these effects, also, its use has been prohibited by statute in several European countries. It is sometimes employed to sweeten wines. It is sometimes used in pharmacy to sweeten elixirs, syrups, etc., and to correct the taste of the alkaloids and bitter principles. 665. Icthyol is a sodium salt of a complex sulphonic acid, having the empirical formula C28H38S30e(NH4)2. It is obtained by the distillation and purification of a pitch-like mineral deposit. It is a dark-brown, pitch-like mass, having a disagreeable, tarry odor. 666. Organo metallic Compounds. — The hydrocarbon radicals can be made to combine with certain metals. They are usually obtained by the action of the iodide of an alcoholic radical upon the metallic element in an atmosphere of H. They are substances which have been put to no use in the arts or in medi- cine, but are of interest principally in chemical synthesis. The hydrocarbon radicals also combine with ammonia, phosphine, arsine, and stibine. These compounds are similar to the ammo- nium compounds, which we shall study later. They are of no therapeutic interest. 390 MEDICAL CHEMISTRY. 667. The Nitro Derivatives of the Hydrocarbons. — These are colorless liquids of ethereal odor, usually insoluble in water. They distil without decomposition and sometimes explode on being quickly heated. They are distinguished from the ethers by not being saponified and by yielding amins on re- duction ; the N not being separated from the hydrocarbon radical. Thus : — CH3NO2 + 3Hj = CH3NH2 + 2H2O. Nitro methane. Methyl amin. These nitro-compounds may be formed by treating the iodide of the hydrocarbon radical with silver nitrate, or, in some cases, by the direct action of nitric acid upon the hydrocarbon. This reaction, however, seldom takes place with the paraffins. The constitution of the nitro compounds is distinguished from the ethers in not being saponifiable, and from the fact that the nitrogen is not split off in their reduction, but remains bound to the carbon. From this we conclude that the nitrogen in them must be directly joined to the carbon, and not linked to it by oxygen, as in the case of nitrous ethers. The graphic formula of O O nitro methane must be considered to be CH. — N^ I or CH, — Nr^ , while nitrous ether must be considered to be CH3 — O — N = O. The nitro-paraflins are not so numerous or important as those of the benzene or aromatic compounds, which will be considered later. 668. Nitrils, or Cyanides of Hydrocarbon Radicals. — Hydrocyanic acid yields two classes of derivatives by the exchange of its H atom for alcohol radi- cals, neither of which can be grouped among the ethers, since they do not go back into alcohols and hydrocyanic acid upon saponification, but decompose in another direction. These two classes of compounds are known as nitrils and iso-nitrils. The nitrils are either colorless liquids which volatilize without decomposition, or solids of ethereal odor, lighter than air and relatively stable. They boil at about the same temperature as the corresponding alcohols. They are formed by heating the iodide of the radical with potassium cyanide, or by heating potassium ethyl-sulphate with potassium cyanide. CH3I + KCN = KI + CHjCN Methyl cyanide. KO\ CjHsO; SOj + KCN = CjHjCN + K^SO^ Potassium ethyl Potassium Ethyl ' Potassium sulphate. cyanide. cyanide. sulphate. They may also be prepared by the dehydration of the ammonia salts of the corresponding acid, by means of PjOj, C^HjO^NHj = CHjCN + 2U.f) QHjONHj = CH3CN + H^O Ammoniurri Methyl cyanide, or Acetamid. Methyl cyanide, or acetate. aceto-nitril. aceto-nitril. or by distilling the ammonium salts of mono basic acids, which contain one atom KETONES. 391 of carbon more than the alcohol which would correspond to the nitril desired. C^HjOjNHj = CH3CN + 2H2O. As a consequence of these modes of for- mation, these compounds are termed the nitrils of the monobasic acids, that is, CH3CN is named aceto-nitril ; CjHjCN, propio nltril, or ethyl cyanide. When these compounds are heated with acids, alkalies, or superheated steam, they break up into the acids from which they were originally prepared, and ammonia. Nascent H converts them into amins (see aceto-nitril, methyl cya- nide). CHjCN is present in the products of the distillation of coal tar. It is a colorless liquid, boiUng at 82° C. (179° F.), is combustible, and miscible with water. The other nitrils of the higher hydrocarbon radicals are only oi theoretical interest. Cyanide^ of the other series of hydrocarbons also exist. Fulminate of Mercury (Hg (CN2) O,) is obtained by warming alcohol with nitric acid and mercuric nitrate. It crystallizes in fine, silky prisms, which explode with great violence on being heated or struck. Fulminate of silver, having a similar composition, is even more explosive. These fulminating compounds are used in the manufacture of percussion caps. The iso-cyantdes, or iso-nitrils, or carbamins, are colorless liquids, easily soluble in alcohol and ether, but slightly soluble, or insoluble, iu water. They have a feeble alkaline reaction, disagreeable odor, and poisonous proper- ties. They are prepared first by healing the iodides of the alcohol radicals with silver cyanide instead of potassium cyanide. CNAg + QH^I = Agl -f C^HjNC Ethyl iso-cyanide . They may also be formed by the action of chloroform, and an alcoholic solu- tion of KOH, upon the primary amins. The iso-nitrils differ from the nitrils by their behavior with water or dilute acids. When superheated with water or with acids in the cold, they split up into formic acid and an amin base. They do not decompose with alkalies as nitrils do. Aceto iso-nitril has the composition CH3NC, while aceto-nitril has the composition CH3CN, i. e., the N and not the C is tied to the CH, group in the iso-nitril. The iso-nitrils, therefore, are generally distinguished from the nitrils by reversing the positions of the C and N. The following graphic formulae will make this distinction clear : — CH, CH, C=N N=C Aceto-nitril. Iso-aceto-nitril. CH3 CHj CH, CHj I I C=N N=C Propio-nitril. Iso-propio-nitril. In most cases the cyanides of the hydrocarbon radicals — nitrils — can be con- verted into acids by heating them with KOH, HCl, or with H^SO^, diluted with its own volume of water, thus : — CH5CN -f 2HjO = CH5COOH + NH, 392 MEDICAL CHEMISTRY. The relation of the derivatives of the various substitution pro- ducts of the hydrocarbons may be illustrated by the following formulae, derived from the first two members of the paraffin series: — Hydrocarbon. Methane, CgH^. Ethane C=H3C=H3. Haloid Ether. • Methyl Chloride, C=HaCl. Ethyl Chloride, C=h,C=H2C1. Monohydric Alco- hol. Methyl Alcohol, C§HaOH. Ethyl Alcohol, C=hC=hPH. Dihydric Alcohul. Ethylene Glycol or Glycol, ChHsChO^H,. Ether or Oxide. Methyl Ether, ^^3 |o. Ethyl Ether, {^f^^^}o. Compound Elher. Methyl Nitrite, CH3— O— N=0. Ethyl Acetate, CHs-O-QHjO. Aldehyde. Formaldehyde, C^^ » Ethyl Aldehyde, C=HaC_^ Ketone or Acetone Can exist only with three carbon atoms. Acetone, C-HaC oC— H3. Acetal. Methylal, CH^^^JJ' .\cetal, C=H,^~^2"s Nilril. Methyl Cyanide, C=H3C=N. Ethyl Cyanide, C^H^ 0=N. Monobasic Acid. Formic Acid, C^^qjj Acetic Acid, C§h^C~qtt Dibasic Acid. Oxalic Acid, C=Oq~][][ ORGANIC ACIDS. 669. The characteristic feature of an organic acid molecule is that it must contain the carboxyl group — COOH. The basicity of the acidwill depend upon the number of these groups contained in its molecule. The. organic acids partake of the general properties of the inorganic acids. They may be referred to the water type, and be considered as one or more molecules of water, in which ORGANIC ACIDS. 393 one-half the hydrogen has been replaced by an organic com- pound radical containing oxygen — a negative radical — while the remaining hydrogen remains as replaceable or basic hydrogen. H— O— H. II— O— C.H,0. H— O— 1 f, „ , , H— O— / * *"* Water. Acetic acid. Tartaric acid. As in inorganic acid only those hydrogen atoms which are linked to the radical by oxygen, are replaceable by a metal or basic radical. Organic acid may be formed by the oxidation of a primary alcohol, or an aldehyde. The presence of an alkali favors the formation of an acid by oxidation. Acids may be monobasic, dibasic, tribasic, etc., accord- ing as their molecules contain one, two, three, etc., carboxyl groups, ( — COOH). Acids may also contain one or more hy- droxyl groups, (OH), which are not basic, because not imme- diately attached to or associated with CO, to form the carboxyl group. The hydrogen of these hydroxyl groups is called alco- holic hydrogen, to distinguish it from the other replaceable hydrogen, designated as basic. The number of hydroxyl groups in a molecule of either an alcohol or an acid is said to be its atomicity. It is evident that the atomicity of an acid may be greater than its basicity, when it is said to be an alcohol acid. Lactic Acid, (H-0—C0CH(0H)CH3 = (c.,H^0 | qh)' ^^ a good example of a diatomic and monobasic acid. The number of organic acids known is very large ; only a few of the most prominent ones, can, therefore, be mentioned here. Of the many series of acids, the most numerous and important are those of the acetic or fatty acid series, corresponding to the marsh gas series of hydrocarbons. The acids of this series are obtained by the oxidation of the corresponding alcohols or aldehydes. CjHj— O— H -f- Oj = C2H3O— O— H + HjO. Alcohol. Acetic acid. 2CJH5OH + Oj = 2CJH3O— O— H. Aldehyde. Acetic acid. They may also be obtained by the action of the alkaline hydroxides upon the cyanides of the radical of the next lower alcohol. CH3CN -f KOH + HjO = NH, -I- KCjHjO,. A few have been obtained by synthesis from carbon monoxide. CO -1- KOH = CHO— O— K. 34 Potass, formate. 394 MEDICAL CHEMISTRY. FATTY ACID SERIES. 670. The following is a list of the principal members of the fatty acid series, general formula C„H2„+iC00H. Fusing Boiling Point. Point. 4°C. 100° C. 17° C. IISOC. -2I°C. 140° C. -20° C. 162° C. -16° C 185° C. -2°C. 205° C. -io°C. 224° C. 14° c. 236° c. 18° c 254° c. 30° c. 270° c. 4.1° t^- 54" <-■. 62° C. 60° c 70° c. 7S°C. 76° C. 77° c. 80° c. yo° C Occurrence. Formic acid, Acetic acid, Propionic acid, Bulyric acid. Valerianic acid, Caproic acid, CEnanthylic acid. Caprylic acid, Pelargonic acid, Capric acid, Laurie acid. Myristic acid. CHOOH, CHjCOOH, CjHjCOOH, CjHjCOOH, C^H^COOH. C5H11COOH, CjHijCOOH. CjHisCOOH, CgH^COOH, CgHijCOOH, CjjH.jCOOH CjjH^jCOOH, Palmitic acid, C15II31COOH Margaric acid, Slearic acid, Arachidic acid, Bebenicacid, Hysenic acid, Cerolicacid, Melissic acid. Ci.HjjCOOH, CjjHjsCOOH, CijH^gCOOH, C,,H,3C00H., C,,H,,COOH, C,,H,3C00H, C„H3„COOH, Red ants, nellies. Vinegar. Sweat, oxidation of oils. Rancid butter. Valerian root. Rancid butter. Oxidation of castor oil. Rancid butter, cocoanutoil. Geranium leaves. Butter. Bay berries. Cocoanut oil, nutmeg, but- ter. Palmitic acid, palm oil, animal fats. Synthesis. Most solid animal fats. Certain vegetable oils. it It (( Fat of hysena. Beeswax. MONATOMIC ACIDS. CnHauOg = CnH-2n -f iCOOH. Of the large number of acids in this group, we shall notice formic, acetic, butyric, valerianic, palmitic, oleic and stearic. 671. Formic Acid, CHO — O — H, is a colorless liquid, of a very acid reaction and sharp, pungent odor. It boils at about 100° C. (212° F.) and solidifies at about 0° C. (32° F.). It exists ready formed in the red ant, stinging nettle and pine needles. It acts as a reducing agent, reducing silver and mer- cury salts and depositing the metals. It is used in silvering glass, to reduce the silver which de.posits upon the walls of the con- taining vessel. The best method of obtaining it is by heating to about 100° to iio°C. (212° to 230° F.) pure anhydrous glycerin MONATOMIC ACIDS. 395 and dry oxalic acid, adding more oxalic acid from time to time, and continuing the distillation. Carbon monoxide dissolved in potassium hydroxide, yields some potassium formate. 672. Acetic Acid, C2H3O— O — H, occurs in the form of acetates, in some vegetable and animal fluids. It is usually obtained by the fermentation of saccharine fluids, after they have undergone the alcoholic fermentation, or by the dry distillation of wood, starch, etc. In distilling wood, gases, methyl alcohol (wood spirit), acetic acid, water, creasote and tar are obtained. The liquid portion is distilled at a gentle heat, when the alcohol is separated. The remaining liquid, containing the acetic acid, is saturated with sodium carbonate, evaporated to dryness, and heated to 250° or 350 ° C. (482° to 662° F.) to char the tarry matters. The resi- due, containing sodium acetate, is dissolved in water, filtered, evaporated, and allowed to crystallize out. If the free acid is desired, the residue, after carbonizing, is distilled with a slight excess of sulphuric acid. This gives a colorless, strongly acid, sour-smelling liquid, which crystallizes at about 1 7° C. (63° F.) and is known as glacial acetic acid. Acetic acid applied to the skin, blisters and causes considerable pain. When not too strong it acts as a styptic. It is soluble in water, alcohol and ether in all proportions. It dissolves resins, camphor, fibrin, and coagulated albumin. It precipitates mucin, and is used to separate this body from its solutions. It is also used, with the aid of heat, as a test for albumin ; but care is taken not to add too much, as it dissolves the albumin. Under the ac- tion of chlorine, acetic acid furnishes a series of chlorine sub- stitution compounds, in which the chlorine is substituted for the hydrogen of the radical ; thus, we have monochlor-, dichlor-, and trichlor-acetic acids. CjHjClOjH, CjH^Cip^H, and C^C]fi.,U. The last of these is mentioned elsewhere as a test for albumin in urine. 673. Vinegar. — This name is given to the mixture obtained by the fermentation of wine, cider, whiskey, molasses, infusion of malt, etc., under the influence of the growth of mycoderma aceti, and should contain at least four per cent, of acetic acid. QHjOH -I- Oj = C2H3O— O— H -t- HjO. Alcoholic fermentation always precedes the acetous. As vinegar always contains more or less of this ferment, called 396 MEDICAL CHEMISTRY. mother of vinegar, it is customary to add some of this fluid to start the process. The fermentation takes place slowly, in vats or casks, because of the small amount of surface presented to the air. The process is rendered very much more rapid by allowing the fluid to trickle over beech- wood shavings or chips, placed upon trays or in perforated barrels, so as to expose a large sur- face to the air. After having passed over the shavings four times, it will be found to be pretty thoroughly acetified. The temperature should be kept at about 25° C. (77° F.). The vinegar of the market is frequently adulterated with — i, water; 2, mineral acids, especially sulphuric ; 3, metallic impu- rities, as arsenic, lead, zinc, copper and tin ; 4, wood vinegar; 5, organic substances, such as coloring matters, capsicum, etc. The addition of water can only be detected by the estimation of the per cent, of acetic acid. The most objectioi^ble adulterant is sulphuric acid. The simplest method of detecting free mineral acids is to evaporate a portion of the vinegar to dryness ; heat the residue to dull redness for some time, to convert the acetates of the alkaline metals into carbonates, which salts can easily be detected by their effervescence with hydrochloric acid. If any free mineral acid existed in the vinegar, it would expel the acetic acid from the alkali metals, and convert them into inorganic salts, which remain unchanged on ignition. Another test for mineral acids is methyl violet. Two or three drops of a solution of this compound (o. i to 100) is added to 25 c.c. of vinegar. If .2 per cent, of any mineral acid be present, the color is blue ; if .5 per cent., blue-green; if i per cent., green. A simple test for sulphuric acid, is to evaporate a portion to dryness in a white porcelain dish, with a little cane sugar. Near the end of the process, the residue becomes black by the charring of the sugar by the acid. A small quantity of sulphuric acid is sometimes added to make the vinegar keep. The poisonous metals likely to be found are mercury (corrosive sublimate), copper, arsenic and lead. These metals may be detected by saturating the vinegar with hydric sulphide, or by separate tests for each. Burnt sugar, capsicum, etc., may be detected by taste or odor in the residue left on evaporation. The acetates are eliminated from the body as carbonates. 674. Propionic Acid, CjHsC^OOH, is a colorless liquid, boiling at 140° C. (284° F.). It resembles acetic acid in odor and taste. Its salts are soluble and crystallizable. It is best prepared by heating ethyl cyanide — propio-nitril — with KOH MONATOMIC; ACIDS. 397 until the odor of ether has disappeared, when the propionate of potassium is obtained. The acid may be obtained by decom- posing this salt with HjSOj. The acid is produced during the putrefaction of various organic bodies, and in the destructive distillation of wood and of resin. 675. Butyric Acid (QHiO. O— H).— This acid is found with other fatty acids, in butter, human perspiration, faeces, flesh juice, and in some beetles. It exists in butter as a glycerid or glyceric ether. Pathologically, it appears in a free state in urine, blood, and ovarian cysts, and in the sputa of gangrene of the lung, and bronchiectasis. It also appears in the intestinal contents, as the result of secondary fermentation of saccharine articles of food. It is best prepared by maintaining at a temperature of 35° to 40° C. (95° to 104° F.) a solution of sugar containing lime or chalk, and sour milk or rotten cheese. A mixture of 10 parts of sugar, I part of cheese and 10 parts of chalk, answers very well. Lactate of calcium is first produced, which afterward changes, under the influence of the ferment of cheese, into butyrate of calcium. The solution should remain alkaline or neutral. Car- bon dioxide and hydrogen are set free. When the fermentation is finished, 30 or 40 parts of crystallized sodium carbonate are added, and the mixture warmed and filtered. The filtrate is evaporated nearly to dryness, and hydrochloric or sulphuric acid added, which sets free the butyric acid as an oily layer, which may be purified by distillation. It boils at 162° C. (323° F.). It is a colorless liquid, with the characteristic penetrating odor of rancid butter. It is soluble in pure water, but separates if solu- ble salts are added to the solution. It is soluble in alcohol, oils and ether. The butyrates are all soluble in water. Isobutyric acid, an isomer of the foregoing, is obtained by oxidation of secondary or isobutylic alcohol. The following graphic formulae show the constitution of these bodies : — H H H H H H H H— C— C— C— C— O— H H— C— C— C— C=° „ I I I I III ~°~^ H H H H H H H BuLylic alcohol. Butyric acid. H H H H H H H— C— C— C— H H— C=C— C— H III III H I H H H „ A—n I =0 "■~^ — O— H '-—O— H Isobutyl alcohol. Isobutyric acid. 398 MEDICAI. CHEMISTRY. 676. Valeric or Valerianic Acids, QH9COOH. — There are four possible isomeric valerianic acids corresponding to the four amyl alcohols. Three are known. Normal Valerianic Acid, CH3CH2CH,,COOH, occurs in angelica and valerian roots, and its araraonium salt is formed by the putrid fermentation of albuminoid matters. It is some- times found in the urine and faeces in smallpox, typhus fever, and yellow atrophy of the liver. It is obtained by distil- ling the powdered root with water. It is best prepared by the oxidation of amylic alcohol. A mixture of one part of amyl alcohol and four parts of concentrated sulphuric acid, is run slowly into a retort containing' four parts of water and five of potassium dichromate. The first product is valeraldehyde, which distils over. By elevating the beak of the retort so as to run the aldehyde back into the oxidizing mixture, it is changed into valerianic acid. The mixture is finally distilled, the distil- late neutralized with sodium carbonate, evaporated and decom- posed with sulphuric acid. Valerianic acid is a thin, oily liquid, boiling at 175" C. (347" F.), and possessing a sour, old cheese odor. The most of the valerianates are soluble in water, and, when moist, smell like the acid. Valerianates of ammonium, bismuth, caffeine, quinine, iron and zinc are used in medicine. 677. Palmitic Acid, C15H31COOH, is the first of the fatty acids, properly so called, which occurs in the animal fats and forms true soaps with the alkalies. On a large scale palmitic acid is made from palm oil. The oil is decomposed, in a still, by super- heated steam at a temperature of about 315° C. (599° F.). When the condensed liquid is run out into receivers, it separates into two layers, the upper of which consists of the free fatty acids. On cooling, palmitic acid forms a white crystalline solid, and is used for making candles. It may also be prepared on a smaller scale by boiling palm oil with potassium carbonate, which con- verts it into potassium palmitate and oleate. On decoinposing these salts with dilute H2SO4, the mixture of palmitic and oleic acids separate. This is washed, dried and dissolved in hot alcohol, from which the palmitic acid crystallizes leaving the oleic acid in solution. Palmitic acid crystallizes in needles which fuse at 62° C. (143.6° F.). It decomposes by distillation, except in the presence of water. Adipocere, a wax-like mass which is sometimes left when animal bodies decompose in the earth, is a mixture of the palmitates of calcium, potassium and MONATOMIC ACIDS. 399 occasionally ammonium. This substance is formed especially in bodies buried in damp soil, or in bodies which remain in the air some time after death. It is found to occur in muscles in a definite order. The amount of adipocere present is a good gauge of the time a body has been dead. Palmitic acid is insoluble in water, and is soluble in alcohol and ether. 678. Stearic Acid, CuHsjCOOH, exists as a glycerid in all solid animal fats, and in many oils. It may be prepared from tal- low by boiling it with potassium carbonate, decomposing the resulting soap with HCl, drying, separating the fatty acids and dissolving in a large quantity of hot alcohol. Afterward, the hot solution in alcohol is partly precipitated by a strong solution of barium acetate. The precipitate is decomposed with HCl, when stearic acid precipitates. This is collected, washed,- dried, and recrystallized from alcohol. Stearic acid is a white, crystal- line solid of the same sp. gr., as water, fusing at 69° C. (156-. 2°F.). Stearic acid exists in fats as stearin mixed with palmitin and olein. These glycerids may be saponified by superheated steam. Stearic acid is insoluble in water but soluble in alcohol and ether. It burns with a luminous flame, and is much employed in the manufacture of candles and soaps. The so-called stearine candles area mixture of palmitic and stearic acids. Both pal- mitic and stearic acids are found in the free state in the intestines during the digestion of fats, a portion of which are decomposed by the action of the pancreatic juice, and sometimes found as white masses in the stools. 679. Margaric AcidjCisHssCOOH, is synthetically obtained. The substance formerly known by this name, and supposed to exist in natural fats under the name of margarin, is a mixture of palmitic and stearic acids. 680. Oleic Acid— Acidum Oleicum (U. S. P.)— CijHa,- COOH, occurs as olein in most fats and oils. It is prepared by boiling olive oil witli potassium carbonate, decomposing the solution with HCl, collecting the oily layer which separates, and heating it with litharge to 100° C. (212" F.) for some hours, when a mixture of oleate, palmitate, and stearate of lead are formed. The oleate is dissolved out of the mixture with ether, and solution shaken with HCl to precipitate the lead. The ether is then distilled away and the impure oleic acid is dissolved in am- monia and precipitated by BaCij. The barium oleate is recrys- tallized from alcohol, and finally decomposed by tartaric acid. Oleic acid is a yellowish, or brownish yellow, oily liquid, having 400 MEDICAL CHEMISTRY. a peculiar lard-like cdor and taste, and becomes darkenedon exposure to the air. Sp. gr. is about .900. It is insoluble in water, soluble in alcohol, chloroform, benzene, oil of turpendne, and other fixed and volatile oils. At about 4° C. (39° F.) it becomes semi-solid, and at lower temperatures a whitish, solid mass. It cannot be distilled without decomposition, except in the presence of steam. When heated to about 95° C. (^03° F.) it begins to decompose, giving off acrid vapors. Its alcoholic solution has a faintly acid reaction upon litmus paper. Equal volumes of oleic acid and alcohol should give a clear mixture at ordinary temperatures, but if any oil be present, it separates in drops. Oleic acid is a by product in the manufacture of candles. The commercial acid absorbs oxygen readily when exposed to the air. By the action of nitrous acid, or nitrous fumes, oleic acid is converted into isomeric elaidic acid, a solid crystalline acid, fusing at 45° C. (113° F.). This acid is formed in the preparation of unguentum hydrargyri nitratis (U. S. P.). The nitrous fumes given off convert the oleic acid of the oil or lard into elaidic acid, which exists in the ointment in combi- nation with mercury. 681. ACIDS DERIVED FROM GLYCOL. The glycols, it will be remembered, are diatomic alcohols, and by oxidation may give rise to two series of acids, thus : /-_OH r— OH I -f O, = j + H,0 C=H2 C=H, OH ^OH and Ethyl glycol. Glycolic acid. Q—on CZP^ ! + 20, = j + 2H,0 fcH, C==o OH • \oH Ethyl'glycol. Oxalic acid. The Other glycols can in the same manner furnish both series of acids, the one diatomic and monobasic, and known as the lactic acid series, and the other dibasic and known as DIATOMIC AND MONOBASIC ACIDS. 40I the oxalic (or succinic) series. These glycols and acids are as follows : — Gi-YCOL Series. Lactic Series. Oxalic Series. CjHj (OH)j „„ — COOH CO.OH Ethyl glycol. '""'i-OH | Glyco''c acid. CO OH QH. (OH), _COOH ""'"VnnTT Propyl glycol. "-2"*_OH CH, ^Xr!lJ Lactic acid. „ —y'y,'^ „^^ Malonic acid. C.H."^" C H -COOH ,. -COOH 4 8_oH "-s^e—oH ''2"4— COOH Butyl glycol. Oxybutyric acid. Succinic acid. DIATOMIC AND MONOBASIC ACIDS. But two acids of this group are worthy of special mention ; viz.: gly colic and lactic acids. CHj— O— H 682. Glycolic Acid, | is found in unripe grapes, CO— O— H and in the green leaves of Virginia creeper. When pure, it forms large, regular crystals, which deliquesce in moist air, and melt at 79° C. (174° F.)- 683. Lactic Acid — Hydroxy-propionic Acid — Acidum Lacticum (U. S. P.). — There are at least three isomeric lactic acids known, and a fourth has been described. Their graphic formulae are : — CH3.CHOH.COOH. CH2OH.CH2.COOH. Ethylidene-lactic acid. Hydracrylic or Ethylene-lactic acid. CH3 In addition to these, sarcolactic acid is well-known, ch.— o— h. CO.O-H Lactic acid is the acid of sour milk and sour cabbage, and is produced by a special ferment, the bacterium lactis, or lactic ferment. It is found in small quantity in the gastric juice, urine, and intestinal juices. It is produced on a large scale by lactic fermentation of cane sugar and glucose. Flour is first treated with dilute sulphuric acid, to convert the slarch into glucose ; the free acid is then neutralized with milk of lime. To this is then added sour milk, and it is allowed to ferment ; care being taken to stop the process before butyric acid fermentation sets in, by heating the mixture 40 2 MEDICAL CHEMISTRY. to boiling. The hot solution of calcium lactate is separated by filtration, evaporated down, and allowed to crystallize. From this salt, the acid may be obtained by saturation with sulphuric acid. It has been prepared synthetically by the oxidation of propyl glycol. A solution containing 75 per cent, of the acid is official in the U. S. P. It is a colorless; syrupy, odorless, very acid liquid, freely miscible with water, alcohol, and ether. It has been used to check lactic and butyric fermentation in the intestinal tract, as an excess of this acid prevents the further growth of the ferment. It has been prepared synthetically by heating alde- hyde with hydrocyanic acid. It is used in the preparation of syrup of the lactophosphates (U. S. P.). Ferrous Lactate is used in medicine. It occurs in pale, greenish-white, odorless, crystalline crusts or grains, permanent in air, and soluble in water. Strontium Lactate, Sr(C3H503)2.3H.^O, also used in medi- cine, occurs as a white, granular powder, soluble in water. 684. Sarcolactic Acid, or Paralactic Acid, is isomeric with the above. It has not been prepared synthetically, but is char- acteristic of muscle juice, and gives to muscular tissue its acid reaction. It occurs in the blood, especially after active muscular exercise. It is found in the urine, and in increased amount after violent muscular exertion, and very strikingly after extirpation of the liver in birds and frogs. It has been found in the fluid of ovarian cysts, and other pathological fluids. It is found in extracts of beef, and may be prepared from Liebig's extract after precipitating with alcohol, acidifying with H2SO4, and shaking the filtrate with excess of ether, which dissolves it. On evapor- ating the ether, dissolving the residue in water and precipitating with zinc acetate, the zinc salt is obtained. By recrystallizing this salt, suspending it in water, and decomposing with hydrosul- phuric acid gas, the acid is obtained in solution. It may be separated by dissolving it out with ether. The acid thus ob- tained is similar in most of its physical and chemical properties to ordinary lactic acid. It is dextro-rotatory, however, while ordi- nary lactic acid is optically inactive. Sarcolactic acid obtained from muscular tissue is said to con- tain another acid, known as ethylene-lactic acid, in small quan- tities. Dead muscle has an acid reaction, which is greater as rigor mortis appears. During life, the acidity increases with active contraction, and diminishes with rest. The acid is probably produced by decomposition of the muscular tissue during con- DIBASIC ACIDS. 403 traction, although some have claimed that the acidity is due to acid phosphates' produced from the phosphates of the tissue dur- ing contraction, while others have thought that the lactic acid is due to the transformation of the glycogen usually found in muscle. Lymphatic, thymus; and thyroid tissues are alkaline during life, but become rapidly acid after death, from the presence of sarcolactic acid.' Tests for Lactic Acids. — Both of these acids give an intense yellow color with a very dilute solution of ferric chloride. If to about 10 c.c. of water two drops of carbolic acid and a drop of ferric chloride solution be added, and to this violet solution a mere trace of lactic acid be added, it instantly changes to yellow (Ufifelmann). This test will show one part of the acid in 10,000 parts of water. Oxybutyric Acid is found in the urine of diabetics, and is mentioned in the chapter on the urine. DIBASIC ACIDS. CO.O— H 68";. Oxalic Acid, I = HaCaOi. — This important acid •* CO.O— H ^ occurs in many plants (Oxalis, Rumex, Rhei) as acid calcium or potassium oxalates. Calcium oxalate is also found in the urine. Oxalic acid is easily obtained by acting upon many organic substances with oxidizing agents. Glycol, glycolic, or acetic acids may be made to yield it. It is best prepared from the carbohydrates (sugar, starch, etc.), by treating them with strong nitric acid, or by fusing with caustic potash. Commercial oxalic acid is prepared by fusing sawdust with a mixture of caustic soda and potash, and treating the oxalates thus formed with hydro- chloric acid. The acid crystallizes in colorless prisms with two molecules of water which they lose at 100° C. (212° F.). It is soluble in eight parts of cold water, and in alcohol. On heating the acid, it is resolved into carbon monoxide, dioxide, water and formic acid. Strong oxidizing agents convert it into carbon dioxide and water. It is a strong dibasic acid, and forms both acid and neutral salts with most of the metals. Oxalic acid easily oxidizes, into CO2 and HjO. This may be effected by chromic acid, potassium permanganate in presence of dilute HjSO,, and even on exposure of its watery solution to 404 . MEDICAL CHEMISTRY. air and sunlight. Dehydrating agents, H2SO4 and H3PO4 de- compose it into CO,C02 and H2O. Oxalic acid resembles mag- nesium sulphate, and has been taken by mistake for this salt. Oxalic acid is both a corrosive and a systemic poison. Death has followed the use of 3j (4 grms) but persons have recovered after faking much larger doses. Much will depend upon the concen- tration of the poison. When the solid or a strong solution is taken, its local effect is most marked, and death may come within half an hour. If recovery takes place, owing to prompt treatment, the aftereffects will be those of any of the corrosive poisons. If the acid is taken in dilute solution, the local effect is much less, or almost wanting. In such cases the poison is ab- sorbed and acts as a systemic poison. Vomiting and cramps are usually, though not always, present. The soluble salts of oxalic acid are almost as poisonous as the acid, but do not have the same local corrosive effect. The treatment should be prompt and judicious. It is im- portant to learn, if possible, the condition in which the acid was swallowed. If in concentrated solution or as the solid, the stomach pump, or even the stomach tube, should not be used. If taken diluted, and the burning epigastric pain is not too severe, the soft stomach tube may be used with care, washing the stomach out thoroughly with lime water, followed with pure water. If lime water is not procurable, milk of magnesia or a solution of magnesium sulphate (epsom salts) may be used. If it is deemed unsafe to use the tube, vomiting may be induced, and the stomach washed out by giving a lukewarm mixture of equal quantities of lime water and sink or well water. Tests for Oxalic Acid. — Calcium chloride gives, even in very dilute neutral or alkaline solutions, a fine white heavy pre- cipitate. The precipitate is soluble in HCl, but not in acetic acid. Silver nitrate gives a white precipitate, soluble in HNO3 and in NH4OH. Lead acetate gives, in not too dilute solutions, a white precipi- tate soluble in HNO3 but not in acetic. It discharges the color of KaMnjOg in presence of dilute H,SO,. 686. Succinic Acid, CsHiC^^^yyjj. — This acid is found ready formed in amber and some other resins, in several plants, in the spleen, in thymus and thyroid glands, in hydrocephalic and hydrocele fluids. It is obtained in small quantities in alcoholic fermentation and in the putrefaction of proteids. DJBASIC ACIDS. 405 It may be prepared by the spontaneous fermentation of tartaric or malic acids. It is one of the products of alcoholic fermentation of sugar, and may be prepared by the action of reducing agents on malic and tartaric acids. It may be obtained in quantity by the dry distillation of amber ; the aqueous portion of the distil- late is heated to boiling, and filtered ; on cooling, crude succinic acid crystallizes out. Succinic acid crystallizes in monoclinic prisms, melting at 180° C. (356° F.), and decomposing into water and succinic anhydride at 235° C. (455° F.). It is soluble in 23 parts of cold water, and very freely soluble in hot water. By adding neutral solution of ferric chloride to a soluble succinate, a brown, gelatinous, ferric succinate is pro- duced j this reaction is used as a qualitative test for the acid. The succinates of the alkaline metals are soluble ; those of the other metals are either slightly soluble or insoluble. There are two isomeric succinic acids, but iso-succinic acid is unimportant. 687. Dibasic Acids Containing Alcoholic Hydroxyl. — The simplest acid of this class must contain three carbon atoms, and in that case may be regarded as being derived from the triatomic alcohol, glycerin. By the oxidation of glycerin we may form two acids, thus : — r—o-H r=H, r— O-H V=H, 7 O-H V=0 I _0— H 1_H L-_H ' OH — H '-OH I I I C=Hi, r=o n=o \0-H \0-H *^— O-H Glycerin. Glyceric Tartronic acid. acid. r CO O-H 688. Malic Acid — Oxy-succinic Acid — C2H3 \ O-H ( CO O-H, may be viewed as a homologue of tartronic acid, or as derived from succinic acid. It occurs in many acid fruits, as cherries, apples, raspberries, gooseberries, rhubarb (stalks and leaves), unripe mountain ash berries, unripe grapes and quinces. It is best pre- pared by nearly saturating the boiled and filtered juice of the berries of the mountain ash with milk of lime. On continued boiling, calcium malate, CaC4H3(HO)04.H20, separates as a crys- talline powder, from which the acid may be obtained by treatment with dilute nitric acid. Malic acid crystallizes in groups of small, colorless, deliquescent crystals. It melts at 100° C. (212° F.), and 4o6 MEDICAL CHEMISTRY. decomposes at 150° C. (302° F.). Putrefactive ferments convert malic into acetic, succinic, butyric and carbonic acids. There are tiiree isomeric malic acids possible, of which two are known. The alkaline malates are soluble ; other malates are slightly soluble or insoluble ; all are crystalline. The malates are easily oxidized and are converted into car- bonates in the animal body. 68g. Tartaric Acid— Acidum Tartaricum (U. S. P.) — O H H O c-c- '■-"■ I I I I is a dibasic, tetratomic acid. (Compare the formulae 0000 H H H H of succinic, malic, and tartaric acids.) Four isomeric tartaric acids are known ; two of which — dextro and lasvo-tartaric acids — are optically active, and two — racemic and mesotartaric acid- — are optically inactive. Ordinary, or dextro-tartaric acid is found in many fruits, particularly in ripe grapes, as acid potas- sium tartrate (cream of tartar), which, during the fermentation of ihe must, is deposited, mixed with yeast, coloring matter, cal- cium tartrate, etc., as a brown crust, or deposit, known as crude argol. Tartaric acid is prepared'from argol by first treating with hot water, filtering, decolorizing with animal charcoal, convert- ing the acid potassium tartrate into calcium tartrate by the addi- tion of milk of lime, then decomposing this with sulphuric acid. Tartaric acid is thus obtained in solution, and may easily be separated by crystallization. Tartaric acid is usually made in the same factories where cream of tartar is prepared in large quantities. It usually occurs in beautiful, oblique prisms, per- manent in the air, soluble in one-half their weight of water, or in 2.5 parts of alcohol, and insoluble in ether.- When heated, it melts at i8o°C. (356° F.) and forms metatartaric and pyrotartaric acids, and tartaric anhydride (CiH^Os). At a higher tempera- ture it decomposes, with a burnt-sugar odor. Tartaric acid has a strong, acid taste. It precipitates calcium in neutral or alkaline solutions, but not in strong acid solutions. Ammonium salts prevent this precipitation. Heated with hydri- odic acid and phosphorus, tartaric is first changed into malic, and then into succinic acid. The principal tartrates are the neutral and acid potassium tartrates, sodio-potassium tartrate (Rochelle Salt) and tartar emetic, or antimonyl potassium tartrate, all of which are men- tioned in another place. Ferro-potassium tartrate and ferro- ammonium tartrate are also used in medicine. They both belong TRIBASIC ACIDS. 407 to the class of substances known as scale compounds ; /. e. , compounds which do not crystallize readily, and are prepared by spreading the material, evaporated to a syrup, upon plates of glass to dry, and then scraping off the thin scales. The above- mentioned compounds occur in the form of garnet-red scales, slightly deliquescent, very soluble in water, but insoluble in alcohol. Tartaric acid is used in making effervescing drinks, in calico printing, and by confectioners, to prevent the crystalliza- tion of the sugar. When taken in too large quantities, it acts as an irritant poison. One ounce has caused death. When taken in not too great quantity its salts are oxidized to carbonic acid, but if taken in very large quantity it may escape complete destruction, and may appear in the urine and perspira- tion. It is, therefore, not so easily oxidized as malic, succinic, and some other organic acids. TRIBASIC ACIDS. 690. Citric Acid— Acidum Citricum (U. S. P.) — CHjCO.OH CH.co.OH-C6H60<{OH)3.— This acid occurs in the juice of lemons, CH (OH)CO.OH currants, gooseberries, beet roots and other plants. It is manu- factured on a large scale from lemon juice, which is clarified by boiling it with albumin, and then saturated, while hot, with powdered chalk or milk of lime. The precipitated calcium citrate is decomposed by an equivalent quantity of sulphuric acid, and filtered from the resulting gypsum. On evaporating the filtrate, the acid crystallizes out in large, transparent, rhom- bic prisms, having an agreeable, sour taste, and containing one molecule of water of crystallization. The acid melts at ioo°C. (212° F.), and is readily soluble in water and alcohol. At 175° C. (347° F.), the acid loses water, and is converted into aconitic acid, C,H,03(OH)3. Solutions of citric acid soon develop mould, and are thereby decomposed. Citric acid forms three classes of well defined salts with the metals. Citrates of the alkaline metals are solu- ble in water. The citrates are decomposed into carbonates in the body, and, in case of the citrates of the alkalies, are elimi- nated by the kidneys as carbonates; hence, these citrates are frequently prescribed in acid conditions of the urine. Citric acid is not known to exert any injurious action upon the econ- omy, even in considerable quantities. Citrates of bismuth, iron, iron and ammonium, iron and qui- 4o8 MEDICAL CHEMISTRY. nine, iron and strychnine, lithium, potassium, bismuth and am- monium, and syrup of citric acid are official in the U. S. P. When boiled with excess of lime water, citric acid precipitates basic calcium citrate. This distinguishes it from oxalic and tartaric acids. 691. Meconic Acid, C40H(CO.OH)3, is found in opium, in combination with the alkaloids. It may be prepared by dissolv- ing in hot water, neutralizing with CaCOjand then precipitating with CaCij. The precipitate may be dissolved in hot dilute HCl and the acid crystallized out. The acid occurs in crystalline plates, dissolving rather sparingly in cold, but easily in hot water and alcohol. Ether dissolves it but sparingly. It has an astringent taste. Solutions of meconic acid give a blood red color with ferric chloride, which is not discharged by HgClj, or dilute acids, but is discharged by stannous chloride and sodium hypo- chlorite. THE PHENOLS. 692. Compounds derived from the Aromatic or Ben- zene Hydrocarbons. — It has been thought best to study the derivatives of the benzene hydrocarbons by themselves, because of certain peculiarities of these compounds, and to avoid making the study of the others too complicated. We have already studied the principal hydrocarbons of this series which interest the phy- sician and pharmacist. The H atoms in benzene may be replaced by halogens, hydroxyl, sulphur or other hydrocarbon organic radicals. In fact the higher members of the series are all pro- duced by substitutions for H in the original benzene nucleus. By the substitution of CI, Br or I for H in the principal chain, or in the lateral chain, we may form a very great number of compounds, few of which are of sufficient interest to claim special study. By the substitution of hydroxyl for H in benzene, we have what is termed a phenol. By the substitution of two hydroxyls for two atoms of H in benzene we have the diatomic phenols. By the substitution of three hydroxyls we have the tri-atomic phenols. It will be seen that in the higher homo- logues of benzene, in toluene for example, CeHsCHj, where there is a side chain, it is possible to substitute the hydroxyl for one of the H atoms of the benzene nucleus, or for one on the side chain. In the first instance we have a phenol, in the second we have an alcohol. That is, the first cannot be oxidized to produce an acid, because the carboxyl group COOH cannot be produced. In the second place we can form COOH by oxidation, and it is therefore a true alcohol. The phenols thus formed have differ- TRIBASIC ACIDS. 409 ent properties from the alcohols. The phenols differ from the alcohols, in not furnishing corresponding aldehydes and acids on oxidation ; in not dividing into water and hydrocarbons under the influence of dehydrating agents, as all alcohols should ; and in not reacting with acids to form ethers. The phenols form with metallic elements, more stable compounds than the true alcohols. These compounds resemble the salts rather than the alcoholates ; i. e. , the phenols exhibit acid properties, while in structure they are alcohols. 693. Phenol-^Phenic Acid — Carbolic Acid — Acidum C-O-H HCe fiCH Carbolicutn (U. S. P.) — ^i. ^^ is met with in the products of c H the destructive distillation of coal and wood, and is found in small quantities in human urine, and in castoreum. In the arts, it is pre- pared from that portion of the coal tar oil distilling between 150° C. (302° F.) and 190° C. (374° F.). This is agitated with a con- centrated solution of caustic soda, when a crystalline carbolate of sodium is formed, while the neutral oils are left unacted upon. After the latter have been separated, the carbolate is decomposed by hydrochloric acid, and the impure carbolic acid thus obtained, again treated with sodium hydroxide. On exposing this solution to the air, the greater portion of the im- purities become oxidized, and separate as a tarry mass. The clear solution of sodium phenate (or carbolate) is again decom- posed by hydrochloric acid, and the resulting carbolic acid separated and submitted to distillation. From the portion passing over below 190° C. (374° F.) phenol separates out as colorless needles on cooling, which melt at 42° C. (108° F.), and boil at 184° C. (364° F.). Pure phenol is a crystalline solid, having a characteristic odor and pungent, caustic taste, producing a white eschar with animal tissues. The crystals are liquefied by the addition of about 5 per cent, of water. This liquid is made turbid by the addition of more water, until 2000 parts are added, when the acid dis- solves to a clear solution. It is soluble in twenty parts of water at the ordinary temperature. The addition of glycerin increases its solubility. It is readily soluble in alcohol, ether, benzene, carbon disulphide, glycerin, and fixed and volatile oils.. Carbolic acid coagulates albumin, and its aqueous solution gives 35 410 MEDICAL CHEMISTRY. a permanent violet-blue color with ferric chloride, while that produced by creasote is first green and then brown. It forms with bromine water, a white precipitate of tribromphenol. When quite pure, carbolic acid is permanent in the air ; but the com- mercial acid frequently changes to a pink or red color. Am- monia and chlorinated soda solution produce a blue color with carbolic acid. Carbolic acid is very much used as an antiseptic, in medicine and in the arts. Some of the carbolates have also been used for the same purpose. Carbolic acid is very poisonous when taken into the body, aiid cases of fatal poisoning by it are not uncommon. Dangerous symptoms have been produced by six or seven drops, and fatal poisoning has occurred from its use as a surgical dressing. The urine is dark colored and smoky in such cases, and its appearance should be watched while using the acid, either internally or locally. 694. Phenates. — When phenol is heated with KOH or NaOH the following reaction takes place : — C5H5OH + KOH = CgHjOK + Hfi. Fhenol. Potassium phenate. The phenol here acts as an acid and gives rise to the name phenic acid or carbolic acid. Certain other metals and the alkaloids may be employed to replace the alcoholic H of phenol,' to give phenates. Mercuric phenate, quinine phenate, and even other salts of this class have been employed in medicine. f CH 695. Cresylic Acid, or Cresol, CeH^ i QTT^ — There are three possible compounds having this formula, the ortho, meta, and para-cresol. Two of these, at least, are found in coal tar together with phenol, and obtained from it by fractional distilla- tion. The impure varieties of commercial coal tar creasote, or carbolic acid, contain in addition cresylic acid or cresol. Cresol may be prepared by dissolving toluidin in sulphuric acid, adding potassium nitrite, and distilling with steam. CjH^CHjNHj + HNO2 = C,H4CH30H + aHjO + Nj. By the same method of preparation the three isomeric cresols are prepared from the three corresponding isomeric toluidins. Ortho Cresol (i : 2) is a crystalline solid, fusing at 31° C. (87.8° F.) and boiling at 185° C. (365° F.). Meta Cresol (1 : 3) is a liquid boiling at 195° C. (383° ¥.). Para Cresol (1:4) is a solid, fusing at 36° C. 96.8° F.) TRIBASIC ACIDS. 41 t and boiling at 198° C. (388° F.). Para cresol occurs in the urine and is a product of the putrefaction of albumin. The graphic formulae of these three compounds are as follows : — OH OH OH C C C ^■\ /^\ ^^\ HCg jCCH, HQ jCH Ha ,CH I II I II I II HC5 ,CH Hq 3CCH, HC5 ,CH %4/ ^4/ %i/ C C C ■ H H CH, Ortho-cresol. Meta-cresol. Para-cresol. 696. Beech- wood Creasote — Creosotutn (U. S. P.) — is a mixture of phenols consisting chiefly of guaiacol and cresols ob- tained during the distillation of wood tar, preferably that of the beech. It contains, in addition to the above, a small quantity of phlorol. It is an almost colorless, yellowish or pinkish, highly refractive, oily liquid, having a penetrating, smoky odor and a burning, caustic taste. Its sp. gr. is 1.070 or higher. It is soluble in about 150 parts of water, but it does not form a perfectly clear solution. It is soluble in all proportions in alcohol, ether, chloro- form, benzene, carbon disulphide, acetic acid, fixed and vola- tile oils. It begins to boil at about 200° C. (402° F.) and most of it distils between 205° and 215° C. (401° and 419° F.). When cooled to -20° C. (-40° F.) it docs not solidify like carbolic acid, but becomes gelatinous. It is inflammable. Its solution gives a reddish-brown precipitate with bromine water, which distinguishes it from phenol. Creasote is employed in medicine, both internally and exter- nally and by inhalations. It is also employed as an antiseptic. To distinguish creasote from phenol, which is often substi- tuted for creasote, the following tests may be applied. Phenol gives with FejCI^ a purple color, while creasote gives a violet which rapidly changes to green and finally to brown, with the formation of a brown precipitate. Phenol is soluble in glycerin, while creasote is not. Phenol precipitates collodion from its solution, while creasote does not. The cresols possess wonderful antiseptic properties, and are less poisonous to the animal organism than phenol. A serious hindrance to their employment as germicides is their in-. solubility. Cresols have recently been introduced as disin^ fectants under special names, as creolin, lysol, solveol, and 4T2 MEDICAL CHEMISTRY. solutol. These substances seem to be derivatives from cresols. Creolin is a dark brown alkaline liquid. It is free from caustic or irritating properties, and may be administered internally. It forms with water a more or less turbid, or milky mixture or emulsion. It mixes with chloroform, ether, and dilute alcohol in all proportions. For external application, it is used in the form of an ointment, or as a i to 2 per cent, aqueous solution. 697. Lysol is a preparation resembling creolin in its properties, and is made by dissolving the fraction of tar oil, which boils between 190 and 200° C. in fat, and afterward saponifying with alkalies, with the addition of alcohol. It is a brown, oily-look- ing, clear liquid, with an aromatic, creasote-like odor. It is said to contain 50 per cent, of cresols. It is miscible with water, forming a clear, saponaceous, frothing liquid ; also with alcohol, benzene, chloroform, and glycerin. It is a good disinfectant, five times more active than phenol, and much less poisonous. It is non-caustic. 698. Solved is a solution of sodium cresol in excess of cresol, and solutol a solution of cresol in cresylate of sodium. It is said to contain 60 per cent, of cresylic acid — one- fourth in the free state, and three-fourths combined with sodium. Cresol iodide has also been introduced into medicine in the form of a light- yellow powder, of not very pleasant odor. It is insoluble in water, but soluble in the oils, alcohol, ether, and chloroform. 699. Cresotic Acids — Oxytoluic Acids — CsHgCHsOH- GOOH. — There are three of these corresponding to the ortho-, meta-, and para-cresols. They are prepared by the action of sodium hydroxide and carbon dioxide upon the cresols, according to Kolbe's method of preparing salicylic acid from phenol. They may also be prepared by melting the homologues of phenol with excess of potassium hydroxide. The cresotic acids all crystallize in long white prismatic needles, which can be volatil- ized in a current of steam. They are soluble with difficulty in cold, but more so in hot water j readily soluble in alcohol, ether, and chloroform. In solution their reactions are similar to salicylic acid. Several salts of cresotic acid have been sug- gested as medicinal remedies. Sodium cresotate, and sodium (CH, para-cresotate, CsHj i OH have been used. The latter (COONa, salt is a fine crystalline powder, with a bitter taste, soluble in 25 parts of water. It has been used in rheumatism, in doses of from 8 to 45 grains. TRIBASIC ACIDS. 413 (CH3 700. Dimethyl Phenols— Xenols—Xylenols.CeHj, ^ CH3 (oh There are six possible dimethyl phenols, four of which have been obtained. We may also have three possible ethyl phenols, ^""^ I OH. (CH3 Thymol — Propyl-meta-cresol, CeH, ^ C■M^, has already (oh been described among the Camphors. (See page 318.) (CH3 701. Carvacrol, or Propyl-ortho-cresol, QHj \ C3H,, (oh. ■exists in the essential oil of origanum. It is an isomer of thymol. It is a thick, oily liquid, which does not solidify even at — 25° C. (—13° F.). It boils at 233° C. (451.4° F.). It is very soluble in chloroform, ether, and olive oil, but insoluble in water. Its iodide is a yellow-brown powder, sometimes employed in medi- cine. It is obtained by the action of iodine upon camphor. It is employed externally as a substitute for iodoform. I OCH3 702. Eugenol, or Eugenic Acid, CeHj.; C3H5, is a body (oh closely resembling carvacrol, obtained from the oil of cloves, cinnamon, bay, pimento or sassafras, by oxidation. Eugenol occurs as an aromatic liquid, boiling at 233° C. (455° F.), slightly soluble in water, freely so in alcohol. It is employed as an antiseptic and is considered superior to phenol. It has also been used internally as a febrifuge. Several compounds of eugenol have also been employed, benzoyl-eugenol being one of them. 703. Chlor-phenols and Brom-phenols. — When chlorine is passed nito phenol, ortho-and para-chlor-phenols are formed. The corresponding Br and I substitution products are obtained by the action of those elements on phenol. Mono-chlor-phenol, CsHjClOH, has been employed as a remedy for inhalations in phthisis and other lung troubles. It is a volatile liquid having an odor somewhat resembling phenol. Bromol, or Tri-brom-phenol, CsH^BrjOH, also called tri- bromophenol, is prepared by the action of Br upon an aqueous solution of phenol. It occurs as a white, crystalline powder of an astringent sweetish taste, and an odor resembling that of Br. 414 MEDICAL CHEMISTRY. It melts at 95° C. (203° F.). It is insoluble in water, but solu- ble in alcohol, ether, chloroform, glycerin and the fatty and ethereal oils. It has been recommended as a local remedy in diphtheria and as an intestinal antiseptic. 704. A Di-iodo Thymol, ^»^^'}c,H,(lO)C-C(lO)C,H,{g^j formed by the action of a solution of I in Klupon an alkaline solution of thymol, has been proposed as a substitute for iodo- form, under the name of annidalin. It occurs as a reddish- brown, odorless powder, which is decomposed under the action of heat and light, with evolution of iodine. This substance is now more generally known as aristol, or di-thymol di-iodide. It is insoluble in water and glycerin, slightly soluble in alcohol and readily so in ether and collodion. It is taken up by fatty oils or vaseline when rubbed with them. When heated in a glass tube, iodine vapors are given off. 705. Tri-nitro-phenol — Picric Acid— Carbazotic Acid, C6H2(N02)30H. — The phenols are acted upon by strong nitric acid, forming mono-nitro, di-nitro and tri-nitro phenols. The first two of these are of little importance to the physician, but the third is employed in the arts as a yellow dye for silk and wool, and is frequently employed as a test for albumin in urine, and as a pre- cipitant of the alkaloids. Two tri-nitro phenols are known, one in which the NO2 group is attached to carbon atoms i, 2 and 4, and in the other attached to 2, 4 and 6. The latter compound is ordinary picric acid. It is prepared by the action of strong nitric acid upon phenol, salicin, indigo, silk, wool and many other organic substances containing the benzene nucleus. It occurs in yellow crystalline plates. It is nearly odorless and has an intensely bitter taste and an acid reaction. It is sparingly soluble in water, very soluble in alcohol, ether and benzene. When quickly heated it detonates. It forms salts with the metals which are explosives. When taken internally in considerable doses it acts as a poison. • Tests. — (i) Its taste is so bitter that this together with its bright lemon yel- low color serves as a delicate test. (2) Its solutions give a green crystalline precipitate with an ammoniacal solution of CuSOj. (3) Glucose heated with an alkaline solution of the acid gives a reddish- brown colored solution. (4) It gives an intense red color when warmed with an alkaline solution of KCN. DIATOMIC PHENOLS. 415 DIATOMIC PHENOLS, 706. These compounds are derived from benzene and its homo- logues by replacing two atoms of hydrogen by hydroxyl. There are three such compounds possible, all of which, in the case of benzene, are well known. Their graphic formulae and the cause of the isomerism is shown by the following : — H I o I c ^'\ HCs 2C— O— H I II HCs 3CH C H H I O I c ./'\ HCs 2CH I II HCs 3C— O- C H -H Ortho-dihydro-phenol. Meta-dihydro-phenol, Pyrocatechin. C,H,(OH),(i : 2) Resorcin. C,H,(OH),(i : 3) H I O 1 c HCs 2CH I II HCs 3CH C— O— H Para-dihydro-phenol. Hydroquinone. CeH,(OH),(l : 4) It will be observed that in the first formula the hydroxyls occupy positions on two adjoining carbon atoms, or I and ^. In the second the positions are I and 3, and in the third they are I and 4. These three include all the possi- ble relative positions of two hydroxyl groups in this molecule. The properties change with the changed position of the second hydroxyl group. {OH OH is most easily prepared by passing SO2 through a warm saturated solution of quinone, QHiGj, when hydroquinone separates in six- sided prisms, fusing at 169° C, and subliming on further heating. It is moderately soluble in water, and easily soluble in alcohol and ether. It has been recommended as an antipyretic, anti- fermentative and antidiarrhceal remedy. It is claimed that it is harmless, even in large doses. It is given in 5- to 8-grain doses. It is used in photography as a de- veloper, owing to its reducing properties. f OH 708 Resorcin — Resorcinol, CgHi i ^„ an isomeride of hydroquinone, has come into prominence recently in the treatment of certain maladies. It forms colorless crystals, melting at 100° C. (212° F.), and boiling at 276° C. (519° F.). It is very soluble 4l6 MEDICAL CHEMISI RV. in water, alcohol, and ether, and possesses a sweetish, harsh taste. It is prepared by fusing certain gum resins (galbanum), extract of sapin-wood ; or, by distilling Brazil-wood, with caustic potash. It is a strong antifermentative. It is now prepared synthetically from benzene but the process is compli- cated. When a small quantity is warmed with twice its weight of tar- taric acid, and lo drops of H2SO4, it gives dark carmine red liquid. A solution of 5 parts of resorcin and 3 parts of white sugar in 100 parts of alcohol, forms a very delicate test for free HCl when warmed in a dish with the suspected fluid. It is used to detect free HCl in the gastric juice. It gives with HCl a purple red color. The physiological action of resorcin is similar to that of phenol, but it is not poisonous. It is given internally as an antiseptic and antipyretic, in doses of two grains, and in some cases as high as 15 grains (i gram). 709. Fluorescein or resorcin-phtalein, CjoHuOa, is also u^ed in medicine, and occurs as dark-brown crystals, which form with ammonia a beautiful red solution with a green fluorescence. 710. Pyrocatechin is another isomeride of hydroquinone that has found use as a remedial agent. It forms flat crystals or plates, readily soluble in water, alcohol and ether. It is pre- pared by distilling extract of catechu, kino and other extracts containing tannin. It is found in crude pyroligneous acid dis- tilled from wood. It has weak acid properties. Solutions of pyrocatechin reduce silver salts in the cold, and Fehling's solutions on warming. If made alkaline they absorb oxygen from the air and turn green. 711. Quinone, C6H4=:02, is a type of a number of compounds obtained by the oxidation of quite a number of para-benzene derivatives. It is a yellow crystalline powder, subliming slowly at ordinary temperatures. Nascent hydrogen or reducing agents convert it into hydroquinone. 712. Orcin — Orcinol — Dihydroxy Toluene, CeHj.CHs- ^OH)2 — is prepared from certain lichens which furnish litmus, cudbear and archil. The lichens are boiled with lime and water, the lime precipitated with CO2, and the orcin extracted with ether. Orcin crystallizes in prisms, has a sweet taste and is soluble in water, alcohol and ether. Orcin forms with ammonia a purple solution, from which acetic acid precipitates orcein, the chief coloring matter of litmus, and the other dyes made from lichens, by mixing them with lime and urine and exposing them to the air. TRI ATOMIC PHENOLS. 417 713. Guaiacol or Methyl-pyrocatechin, QH, i ^„ ' is a constituent of creasote,of which it constitutes about 60 to 90 per cent. It is prepared by fractional distillation of beech-wood crea- sote, collecting that coming over between 200° and 205 C. It is a liquid having a pleasant odor, and boiling at a little above 206° C. (401° F.). Its sp. gr. is 1. 133 at 15° C. (59° F.). It is not very soluble in water, requiring 85 parts of water to take up one part of it. It has been introduced as a remedy in tuberculosis in place of creasote. It is best given in capsules. Guaiacol Iodide, Guaiacol Carbonate and Guaiacol Salicylate have been prepared- and proposed for the same pur- poses as guaiacol. ( OCH 714. Benzoyl-Guaiacol — Benzosol — CeH, -j QpQo ti is a crystalline compound of guaiacol in which the H of the OH group has been replaced by benzoyl. It is prepared by first forming the potassium salt of guaiacol, and warming it with benzoyl chloride. Or, by the reaction between guaiacol and benzoic anhydride. Benzosol is a colorless, tasteless, nearly odorless crystalline powder. It is insoluble in water, soluble in hot alcohol, in ether and chloroform. It contains 54 per cent, of guaiacol. It should not melt below 44° C. (111.2° F.). Guaiacol and its derivatives are not easily oxidized in the body, and are usually partially excreted in the urine, and may be detected in that fluid one-half hour after taking a single dose. It may be detected by distilling the urine with HjSO, (dilute), and adding a drop or two of ferric chloride solution, when, if guaiacol is present, it will give a reddish-brown color. Benzosol is used for the same purposes as guaiacol, and it is decomposed by the alkalies in the same manner as salol. It is given internally in 4 to 12 grains. TRIATOMIC PHENOLS. 715. Phlorogiucin, C6H3(OH)3, is obtained by the fusion of potash or soda with various resins and resorcin, or by the action of alkalies upon phloretin. It occurs as large prisms, which dissolve in water, alcohol, and ether, and possesses a very sweet taste. Its solutions give a dark violet color with FcjCIb. A solution of two parts of phlorogiucin and one part of vanillin in 36 41 8 MEDICAL CHEMISTRY. thirty of absolute alcohol, is used as a very delicate test for free HCl in gastric juice. It. will detect one part of HCl in 20,000 parts of water (Giinzburg). 716. Pyrogallin, Pyrogallol, or Pyrogallic Acid, f 0-H CeHs, ^ 0-H. — This acid is a trihydro-benzene, and is prepared (O-H by heating gallic acid,C6H,(OHl3C02H, to 300° C (572° F.). It crystallizes in white, shining needles, and gives a dark-blue color with ferrous, and red with ferric salts. An alkaline solution, when exposed to the air, rapidly absorbs oxygen, and assumes a dark color. Silver and gold salts are reduced, in the light, to the metallic state by it; hence it is used as a developer in photography. It has been used in the treatment of skin dis- eases. 717. Gallaceto-phenone, C2H3O, CeH2(OH)3, isa derivative of pyrogallol, containing the radical of acetic acid. It is a pale- yellow crystalline powder, readily soluble in hot water, and in alcohol and ether. It is soluble in glycerin, but sparingly solu- ble in cold water. It has bsen used as an exiernal remedy in psoriasis. 718. Aromatic Alcohols differ from the phenols in consti- tution. They all contain tli« group of atoms CHjOH, and by the oxidation of this group it becomes COOH, carboxyl, with the formation of an aldehyde and an acid, thus: — CjHsCHjOH + Oj = CjHjCOH + 0^ = CeH^COOH Beiizy lie alcohol. Benzoic aldehyde. Benzoic acid. Benzylic Alcohol is formed by distilling benzoic aldeh>de with KOH. It is a colorless Liquid of theoretical interest only. 719. Benzoic Aldehyde, CeHjCOH, is a constituent of bitter almond oil, and is a product of the decomposition of amygdalin, along with hydrocyanic acid, glucose, and benzoic acid, under the action of emulsin ferment. It may be prepared by a number of synthetic reactions. It is prepared from the oil, by forming a crystalline solid with sodium bisulphite, separating the crystals and after dissolving them in water decomposing with a strong solution of NajCOj. It is a color- less, oily liquid with the odor and taste of bitter almonds. Sp. gr. 1.043, and boiling point 179° C. (354.9° F.). Oxid- izing agents give benzoic acid, and nascent hydrogen gives benzylic alcohol. When pure it is not poisonous, but the com- mercial article is seldom free from hydrocyanic acid. AROMATIC ACIDS. 419 720. Salicylic Aldehyde— Salicylal—Salicylous Acid, CjHi -j Q„ or Oil of Spirae (meadow sweet) is obtained by oxidizing salicin with KiCr^O, and HjSOj, and distilling off the aldehyde. It may be pre|)ared synthetically by the action of chloroform and KOH and phenol. Salicylic aldehyde is a colorless fragrant liquid, sp. gr. 1.17, and boiling at 196° C. (384.8° F.). It is sparingly soluble in water, but freely in alco- hol. It gives an intense violet color with Fefilg. Cuminic Aldehyde, CsHnCOH, occurs in the aromatic oils of cummin, caraway, and water- hemlock. Anisic Aldehyde, CeH^OCHjCOH, is obtained as a fragrant oil, by oxidizing the oil of fennel, and oil of anise with HNO3. Vanillic Aldehyde or Vanillin, QHjOjCOH, is extracted from the pods of the vanilla bean — Vanilla planifolia. It is now made synthetically from coniferin, a glucoside found in the bark of trees of the conifera family. AROMATIC ACIDS. c-c" 721. Benzoic Acid, hc c— co-o— h— C7H5O2H. — This \ _ / jjC = Cjj acid occurs in gum Benzoin, and in the leaves of the aspen ; also found in the urine of herbivorous animals. Benzoic acid is prepared from gum benzoin by sublimation. The powdered resin is gently heated in an iron pan covered with a perforated paper cover; over this is placed "a paper or felt cone; the benzoic acid is sublimed and collects on the inner surface of the cone. It is also prepared by boiling the resin with milk of lime, filtering, concentrating the filtrate by evaporation, and precipitating the acid with hydrochloric acid. It is also prepared from naphtha- line, CioHg, occurring in coal tar,- and from hippuric acid found in the urine of cows. Properties. — Benzoic acid occurs in large, thin, brilliant plates, or needles ; it melts at 120° C. (248° F.) and boils at 250° C. (482° F.), but sublimes at a lower temperature. It is soluble in hot water and alcohol, but sparingly soluble in cold water. It has a peculiar, aromatic, irritating odor. The benzoates are generally soluble in water. 420 MEDICAL CHEMISTRY. The benzoates of ammonium, lithium and sodium are official. The one most used is ammonium benzoate. This salt occurs in colorless and transparent, prismatic crystals, or in white and granular crystals, becoming yellow on long exposure to the air. It has a slight odor of the acid, a saline, afterward bitter taste ; soluble in 5 parts of water. The sodium salt is soluble in 1.8 parts of water, has a sweetly astringent taste, is free from bitterness, and has a neutral reaction. The acid and its salts have an antifermentative and antiseptic action. The benzoates may be taken internally without harm. They are eliminated partly unchanged and partly as hippuric acid. ' Solutions of benzoates give a flesh-colored or reddish precipi- tate with ferric chloride. 722. Salicylic or Oxybenzoic Acid. — Hc_c_0-H / \ HC C— CO-O-H = CoHifOHjCOjH. \ ^ C — C H H This acid occurs in the flowers of several species of spircRa, and its methyl ether, CgHj ■< pooppr > forms a large part of oil of wintergreen, from which it was formerly prepared. It is now prepared on a large scale by passing COj into a heated retort containing sodium carbolate CjHjONa + CO, = CeHi(OH)CO.ONa and decomposing the mass with hydrochloric acid, to obtain the acid. When pure, salicylic acid occurs as fine, white, prismatic, needle-shaped crystals, permanent in air, having a sweetish, slightly acrid taste and acid reaction ; soluble in 450 parts of cold water, and in 2.5 parts of alcohol. Its solutions give an intense violet color with ferric salts. This is used as a test. Salicylic acid is sometimes added to wines, beer, and other arti- cles of food, as a preservative, a use which should be prohibited. The salicylates of potassium, lithium, sodium, bismuth, and some of the alkaloids are used in medicine. The salicylic ethers are very numerous. (See Art. 619.) 723. Closely related to salicylic acid is a glucoside of oxyben- zoic alcohol, called salicin. prr rOH f, „ rOH Oxybenzoic alcohol. Salicin. AROMATIC ACIDS. 42 1 Salicin is found in the bark of different kinds of willow and poplar, and in castoreum. It is prepared by boiling the bark with water and lead oxide, filtering, precipitating the lead with hydric sulphide, and evaporating down. The salicin separates from the solution in fine, colorless, needle-like prisms, having a very bitter taste and neutral reaction ; soluble in 28 parts of water, and in 30 parts of alcohol ; insoluble in ether or chloro- form ; very soluble in hot water. When heated with acids it yields glucose and seligenin. It is used in medicine. 724. Gallic Acid — Tri-oxy-benzoic Acid — C6Hj(OH)3.- CO.OH, is prepared from gall-nuts by keeping them in a warm, moist place until they undergo fermentation, extracting the mass with boiling water and crystallizing. It may be obtained from tannic acid by boiling with dilute acids or alkalies, or by spon- taneous fermentation, as above described for gall-nuts. Gallic acid crystallizes from water in fine, silky needles, readily soluble in three parts of boiling water, in ether and alcohol. It gives a blue-black precipitate with ferric salts, and reduces the salts of silver, mercury and gold. Its normal salts are perma- nent, but their solutions readily decompose. It has a strong astringent taste, and is used in medicine, in common with tannin, as a haemostatic and astringent. 725. Sulpho-carbolic Acid — Ortho-phenyl Sulphonic Acid — CgH^HO.SOjOH. — If one part of crystallized carbolic acid be mixed with one part, by weight, of strong sulphuric acid, phenyl-sulphonic or sulpho-carbolic acid is formed. C5H5OH -f HjO^SO^ = CjHpH.SOjOH -f Yif). If this solution is diluted with water, and barium carbonate added in excess, a solution of barium sulphocarbolate is pro- duced. From this salt the other salts may be prepared. The acid is a reddish viscid liquid, soluble in water. It has antiseptic properties, and may be used internally. It is non- poisonous and non-irritating. The sodium and the zinc salts have been employed in medicine. Sodii Sulphocarbolas (U. S. P.) is a colorless transparent crystalline solid, with a cooling, saline, slightly bitter taste. It is soluble in 4.8 parts of water and in 132 parts of alcohol. Its solutions give with FejClg a pale violet color. 726. Sozoiodol — Di-iodo-para-phenolsulphonic Acid, CsHjIjOH.SOjOH, is a crystalline solid, occurring in acicular prisms, readily soluble in water, alcohol and glycerin. 422 MEDICAL CHEMISTRY. It is prepared by the action of a solution of iodide and iodate of, potassium upon sulphocarbolate of potassium dissolved in dilute HCl. It has been used as a substitute for iodoform in surgical dressings. roH 727. Salicyl-sulphonic Acid, CeHs.] COOH, is formed (.SO2OH by the action of strong sulphuric acid upon salicylic acid. It separates from the mixture as a white, crystalline powder, very soluble in water. It has been used as a very delicate test for albumin in urine, with which it gives, even in dilute solutions, a voluminous coagulum. ORGANIC BODIES CONTAINING NITROGEN. Amins, Amids, Imids, Nitrils. 728. We have frequently spoken in these pages of types of compounds, especially of the water type. We now come to speak of compounds constructed upon the ammonia type . (^ Ammonia, N-j H, is a type of a large number of organic (^ compounds. An amin (or amine) may be regarded as formed from ammonia by replacing one or more of the H atoms by hydrocarbon radicals. When formed from one molecule of NH3 they are called mon-amins ; when from two or three, they are called di-amins and tri-amins respectively. Primary, secondary and tertiary amins are formed by replacing one, two, and three atoms of hydrogen respectively. We may represent these different classes of atnins as follows : — MON-AMINS. Primary. Secondary. Tertiary. f " f C,H, fCH, rcH, N H. N \ H . N \ CI-I3. N-^CsHj. (h Ih . Ih UeH, Ammonia. Ethylamin. DImethylamin. Methyl-diphenyl-amin. DI-AMINS. fH, fCA (C,H, rc,H, nJh,. nJh, nJc,h,. nJc,h, Ui, (H, u, 1 iW, Condensed Ethylcne-dlamin. Diplj.enylene-diamin. Diethylene-diethyl- ammonia: diamin. ORGANIC BODIES CONTAINING NITROGEN. 423 Amins all have basic properties, and, like NH3, combine directly with acids to form salts. Amids may be regarded as formed by replacing the hydro- gen atoms in ammonia with negative or acid radicals, as : — H ^N. [3OJ C,H3( Acetamid. These bodies are classified and named like the amins. Second- ary and tertiary amids, with very few exceptions, are unknown. They differ from the corresponding acids in containing amid- ogen, NHj, in place of hydroxyl, OH. Thus: — HOCjHjO. HjOjCO. Acetic acid. Carbonic acid. HjN— QHjO. (H,N)jCO. Acetamid. Carbamid (urea). Acid Amids or Amido-acids are formed by replacing a part of the hydroxyl in a polybasic acid by amidogen, NH^, thus: — NH,.IIO.CO. NH^HOQOa. Carbamic acid. Oxamic acid. The hydrogen of the amidogen in these compounds may be furttier replaced by hydrocarbon radicals, thus : — Ftienyl oxamid. Hippuric acid, or benzamidacetic acid. Imids differ from the amids in containing the radical NH, where the latter has NHj, thus : — NH.,CO.OH — HjO = NHCO. Acid carbamid. Carbimid.^ Tne carbamids are converted by heat into isomeric bodies, which may be regarded as compounds of nitrogen with a triad radical, and known as nitrils, thus: — f (CjH^), . Nj \ Hj gives N { C3H5, HjO and CN.CjH.. (.CO '^ Diethyl carbamid. Propionitril, Ethyl cyanide. 729. Amins. — Of the large number of compounds which belong to this class of bodies, we can only mention a few in detail. As before mentioned, the amins are bases, or organic alkalies. 424 MEDICAL CHEMISTRY. They unite directly with acids to form salts, and, with platinic and auric chlorides, to form double salts similar to those formed with ammonia. When heated, amins expel ammonia from its salts. The lower members of the group are gases, while the higher members are liquid or solid. The amins containing the lower alcohol radicals bear the closest resemblance to NH3, but are more strongly alkaline. In some cases they are caustic. They have an ammoniacal odor. They combine directly with acids, like NH3, to form salts. They precipitate the metallic salts, the precipitate being often soluble in excess of the reagents. The lower members are combustible gases, soluble in water. The solubility decreases as the carbon increases. They are lighter than water and ammonium bases, /. ^., these compounds, which resemble NHjOH in constitution, are ' solid hygroscopic and resemble KOH in properties. Some of these, bodies occur in nature ready formed. The most of them, however, are products of synthesis. Methylamin and trimethylamin occur ready formed. 730. Preparation of Amins. — First : By treating the cyanate of the alcohol radical with a solution of KOH. CNQH5 + 2KOH = QHjNH + K2CO3. This reaction yields only primary amins. Second : By heating a concentrated solution of ammonium hydroxide with the chloride, iodide, bromide, or nitrate of the radical. NHjH + CHsI = NHjCHj + HI Ammonia. Methyl iodide. Methylamin. HI -f NH2CH3 = NH2CH3HI Methylamin. Methylammonium iodide. Treated with KOH, NH^CHsHI + KOH = NHjCH, + Kl + HjO Methylamin. Treated with CH3I, CH3I + NH.CH, = NH(CH3),HI. This treated with KOH gives NH (CH3\. By treating these last compounds with a fresh quantity of CH5I, we have the fol- lowing : — NH(CH3), + CH3I = NrCH,),! Te.tra-methylanimoniiim iodide. This final result of the substitution with CH3I cannot be decom- posed on distillation with KOH solution. By using ethyl in the ORGANIC BODIES CONTAINING NITROGEN. 425 above series of reactions, in place of CH3, we obtain a series of amins, in which C2H5 takes the place of CH3. Numerous iso- mers exist among the amin bases. When combined with acids, amins behave like NH3, the ammonium bases like NHiOH. The salts thus obtained are white, crystalline, frequently hygroscopic, compounds, easily soluble in water. The chlorides form double salts with PtCl,, similar to aNHjCLPiCli. 731. Hydroxyl Amin, (NH3O or Nh ). — This compound, O-H closely related to ammonia, may be regarded as a molecule of ammonia in which one hjdrogen atom has been replaced by the hydroxyl radical. Prepared by treating tin with dilute nitric acid, or a mixture of this and hydrochloric acid. The nascent hydrogen generated, reduces the acid and forms the above com- pound, which combines directly with the remaining free acid. HKO3 + 3H, = H3NO + 2H,0 It is an unstable liquid, not obtainable in a free state, and possesses decided basic properties — /. e. , it cojors red litmus paper blue, and combines directly with acids to form salts. H3NO -t- HCl = NHjOH.HCl Hydroxyl amin. Hydrocblorate of hydroxyl amin. The hydrocblorate has been used as a local application in certain fkin diseases, such as psoriasis, lupus, etc. 732. Methylamin, NH2CH3, occurs in certain plants (Mer- curialis perennis), in the distillate from bones and wood, and in herring brine. It is formed in many decompositions of nitro- genous bodies. It is more strongly basic than NH3. It has a power- ful ammoniacal odor, is soluble in water, and its solution behaves with metals like NH.OH. It is a colorless inflammable gas. One volume of water dissolves 1154 volumes of the gas. It forms a well-defined series of methylamin salts with the acids, which are generally crystallizable and soluble in water. Dimethylamin, NH(CH3)2, occurs in Peruvian guano and pyroligneous acid. 733. Trimethylamin, NH(CH3)3, is pretty widely dis- tributed in nature, is found in herring brine, chenopodium, arnica flowers, and blossom of the pear. It also occurs naturally in cod-liver oil, guano, human urine, in ergot and many flowers. It may be prepared by the action of potassium hydrate on many of the vegetable substances, such as alkaloids, etc. It is an oily liquid, having a disagreeable odor, is strongly alkaline, soluble 426 MEDICAL CHEMISIRY. in water, alcohol, and ether. It combines with acids to form crystallizable salts. These three methylamins, above described, are produced by the putrefactive decomposition of animal mat- ters, being accompanied by smaller quantities of other amins, and peculiar alkaloids known as ptomaines. It has been discovered in the residue from the evaporation of water contaminated with sewage. Trimethylamin occurs in yeast, and is frequently ob- tained by the distillation of distillery waste. Propylamin, NH2C3H,, is a colorless liquid, boiling at 50, °C. (122° F.) Its hydrochlorate has been used in medicine. 734. Tetramethylammonium hydroxide, N0H(CH3)i. This compound is obtained by decomposing the corresponding . iodide, NI(CH3)4. It is a crystallme solid, very soluble in water, a stropgly caustic alkali resembling ammonium hydroxide. It forms crystallizable salts with acids. 735. Cholin,trimethyl-oxethyl-ammonium hydroxide, NOH(CH3)s(C2H50), occurs in combination in the human body, in the complex substance known as lecithin. It was first dis- covered among the decomposition products of the bile. It is a colorless fluid of oily consistency, possesses a strong alkaline reaction, and forms deliquescent salts with acids. The salts with HCl, PtClt and AuCla are the most important. Cholin is a most unstable body, the mere heating of its aqueous solution sufficing to split it up into glycol, trimethylamin, and ethylene oxide. It may be prepared from the yolk of eggs by decompos- ing the residue of the yolk left after complete extraction of the substance with alcohol, by boiling it for an hour with Ba02H2. The Bfe compound is decomposed with CO2 and the cholin pre- cipitated from this solution with PtClj. By oxidation with nitric acid it yields an extremely poisonous alkaloid, muscar- in, CjHisNOj. Cholin itself is more or less poisonous and is now recognized as one of the ptomaines which occur in putrefy- ing animal matters. 736. Neurin, Tri-methyl-vinyl ammonium hydroxide, NO-H j >, TT ''^- — This substance is closely related to cholin both in composition and origin. It is a decomposition product of lecithin and protagon, and is formed by the putrefactive decom- position of animal tissues. It is one of the alkaloidal bodies known under the name of ptomaine. It is, like cholin, a syrupy fluid with strong alkaline reaction and is extremely soluble in water. It forms double salts with platinum and gold, similar. to ORGANIC BODIES CONTAINING NITROGEN. 427 those of cholin. Neuriii is a much more powerful poison than cholin. 737. Muscarin, NOH(CH3)2C2H502, is closely related to cholin and .neurin. 'It occurs in the poisonous mushroom, Agan'cus muscarius, and is produced during putrefactive decom- position of albuminoid substances. The free alkaloid occurs in very deliquescent crystals, colorless, odorless, tasteless, and strongly alkaline. It is soluble in water and alcohol in all proportions, sparingly soluble in chloroform, and in- soluble in ether. It is a more powerful base than ammon- ium hydroxide, and forms a series of salts. Like cholin and neurin, it is a very active poison. The symptoms of muscarin poisoning are salivation, vomiting and diarrhoea, contraction of the pupils, diminution of the rapidity of the pulse, interference with respiration and locomotion, gradual depression of the heart's action, and finally death. Atropine is physiologically antagonistic to muscarin and diminishes its intensity of action. 738. Phenylamin, or anilin, NHjCsHj, is the best known amin. It is obtained from benzene by first converting this into nitro-benzene, by the action of concentrated nitric acid. QH, + HNO3 = CeHjNO^ + H2O. Nitrobenzene is generally a brown or pale yellow, strongly refractive liquid, boilmgat 220" C. (428° F.); it has a burning, sweet taste, and an odor resembling that of bitter almonds and cinnamon. It is used in perfumery under the name of essence ofmirbane. It is a violent poison. When treated with nascent hydrogen, generated by zinc and sulphuric or hydrochloric acid, anilin is produced. C^HsNO^ + 3H2 = CeH^NHj + 2H,0. Nitrobenzene. Anilin. The anilin combines with the acid present, forming crystalliza- ble salts. Like all the amins, it acts as a base, uniting directly with acids. Anilin is, when pure, a colorless, oily, refractive liquid, boil- ing at 182° C. (359° F.), and is insoluble in water. It is the basis of a large number of beautiful coloring matters, very much employed in dyeing and calico printing. In 1858, Perkins obtained a purple dye, Tsy acting upon anilm oil with potassium dichromate and sulphuric acid. Other colors were soon ob- tained ; greens, yellows, reds, blues, violets, and black have all been obtained from anilin. These dyes are soluble in alcohol 428 MEDICAL CHEMISTRY. and glycerin, and are used for a variety of purposes. They are not very permanent. Anilin is easily detected by the addition of a solution of sodium hypochlorite (chlorinated soda), with which it gives a purple- colored solution. Anilin is a powerful antiseptic, especially in its action on the tubercular bacillus. Anilin is a powerful narcotic poison, whether taken internally, or inhaled .as vapor. The salts, when pure, are comparatively innocuous. 739. Diamins. — Few of the diamins known are of import- ance to the physician or pharmacist. Some of them have been discovered among the products of putrefaction of albuminoid substances, and it is quite probable that some of the natural vegetable alkaloids belong to this class of bodies. CjHioNj. — This is a synthetical compound recently introduced as a solvent for uric acid. It is prepared by the action of ammonia on ethylene bromide or chloride. The reaction is complex, giving salts of a number of bases. When this product is distilled, it yields a distillate between 130° C. and 180° C. (266° F. to 356° F.) from which diethylene-. diamin separates. It is isolated by forming a dinitroso piperazine by the action of a nitrite. This product, when treated with HCl, evolves nitrous acid and hydrochlorate of piperazine. Piperazine is a white, lustrous, crystalline solid, melting at 104 to 107° C. (219.2° F. to 224.6° F.) and boiling at 145° C. (293°.F.). It is very soluble in water. It absorbs water and CO2 from the air and becomes liquefied. The aqueous solution is nearly tasteless and has a strong alkaline reaction. The compound which it forms with uric acid is 17 times more soluble than lithium urate, it being soluble in 50 parts of water. It is not decomposed in the body and is excreted in* the urine as a neutral urate. 741. The amids differ from the amins in having an acid radical where an amin has a hydrocarbon radical. They may be primary, secondary, or tertiary. They may be mon-amids, di-amids, or tri-amids. The primary 'mon-amids containing radicals of the fatty acid series are solid, crystallizable bodies, neutral in reaction, volatile without decomposition, and are usually soluble in alcohol and ether. They unite with acids to DERIVATIVES OF ANION. 429 form salts. They also unite with certain alkaline hydroxides to form metallic salts. 742. Formamid, NHjCHO, is a colorless liquid, soluble in water and alcohol, boiling at 192° C. (387.6° F.) with partial decomposition. It is prepared by heating ethyl formate with an alcoholic solution of ammonia or by dry distillation of ammo- nium formate. It combines with chloral to form a compound which has been introduced into medicine as a hypnotic under the name of chloralamid. ("CHO 743. Chloralamid — Chloral-formamid — NH^OH ( CCI3CH It occurs in the form of colorless, odorless, faintly bitter crystals, fusing at 115° C. (239° F.), and is sparingly soluble in water. It requires about 20 parts of cold water, or i}4 parts of 96 per cent, alcohol, to dissolve one part of the substance. Hot water decomposes it into chloral hydrate and ammonium formate. The same effect is produced by alkalies, but not by dilute acids. It is employed as a hypnotic in from 10 to 40 gr. doses. Chloralimid, HN -j pp, p, is a compound closely related to chloralamid. It is formed by the action of ammonium acetate upon chloral hydrate, or by the action of heat upon chloral ammonium. It is a crystalline solid, sparingly soluble in water, readily soluble in ether, alcohol, and in the fatty oils. When heated to about 180° C. (356° F.) it decomposes into chloro- form and formamid. It is very stable, being unaffected by light, air, or moisture. It has been employed in medicine as a hyp- notic, but has since been discarded. Acetamid, N -{ H , is obtained by heating ethvlacetate (.QH3O and aqua ammonia, and purifying by distillation. It is a solid, crystalline substance, very soluble in water, alcohol, and ether. Strong alkalies decompose it into ammonia and acetates of the alkaline metals. DERIVATIVES OF ANILIN. The remaining H atoms of the original ammonia, from which anilin is supposed to be derived, may be replaced by a consider- able number of radicals. We may substitute CI for the H, form- ing several isomeric chlor-anilins. In all such cases the N is -430 MFDICAL CHEMISTRY. assumed to be attached to C atom number one of the benzene ring. A large number of isomeric compounds are thus pro- duced, none of which have been employed in medicine. The nitro derivatives, which may easily be formed, are not employed in medicine. The anilids may be considered as a class of com- pounds in which one or more of the remaining H atoms in anilin have been replaced by an acid radical. They may also be regarded as amids, a part of whose remaining H of the amidogen group has been replaced by phenyl. (CeH^ 744. Acetanilid — Antifebrin— N ^ C^Hfi, differs from ani- lin in having the radical of acetic acid substituted for one hydrogen atom. It is prepared by the distillation of anilin acetate, or by boiling anilin with glacial acetic acid. It occurs in white, shining plates, melting at 112.8° C. (235° F.), and boiling at 292° C. (558° F.). It is sparingly soluble in cold water, but is more freely soluble in hot water, from which it crystallizes on cooling. It is very much employed in medicine as an antipyretic, i. e., to lower the bodily temperature in fevers. It is used in the arts for the pre- paration of derivatives of anilin. It is prepared by the prolonged action of pure anilin upon glacial acetic acid at a high temperature, submitting the mixture to fractional distillation, collecting what passes over at 295° C. (563° F.), and recrystallizipg from boiling water. CiH^NH, + CjHjO.H = CeH5NHC,H,0 -I- H,0. Anilin. Acetic acid. Acetic anilid. It is official in the U. S. P. and in several foreign countries. It is identified by the development of a yellow-green color with a green efflorescence (flavanilin) when heated for some time with an equal weight of ZnClj. Acetanilid is only partly decomposed in the animal body, being excreted in the urine in the form of complex phenols. Antifebrin is the copyright name of acetan- ilid. 745. Methyl-acetanilid, or Exalgin, N-^ C2H3O, is pro- (.CH, duced by the substitution of CH3 for H in the acetanilid. It is formed by the action of methyl iodide, CH3I, upon sodium acetanilid. It occurs as a tasteless, crystalline powder, with a melting point of 100° C. (212"^ F.), and boiling without decom- DERIVATIVES OF ANILIN. 43I position at 240° to 250° C. (464° to 482° F.). It is readily soluble in alcohol, but with difficulty in water. It is employed in medicine for the relief of pain, and is best given in capsules or powders. 746. Hydrazins. — The hydrazins are a series of peculiar bases, mostly liquid and closely resembling the amins. They differ from them in containing two atoms of N instead of one, and in their ability to reduce an alkaline cojjper solution (Fehl- ing's) in most cases even in the cold. They are derived from diamidogen or hydrazin, NHjNHj, of which little is yet known. In hydrazin, as in ammonia, we may replace one or more of the H atoms with a hydrocarbon radical. If one H atom be replaced we have a primary hydrazin ; if two are replaced, we have a secondary hydrazin. Thus Ethylhydrazin, C2H5NH — NHj, is a primary hydrazin. Diethyl hydrazin, (CzHjlj^N— NHj, is a secondary hy- drazin. 747. Phenylhydrazin, CeHsNH — NHj, is a colorless, crys- talline solid, melting at 23° C. (73° F.) to a colorless oil which boils at 233° C. (451° F.) without decomposition. It combines with HCl to form phenylhydrazin hydrochlorate, CsHjNjHsHCl, which forms white, crystalline plates. Like all hydrazins, it is characterized by its strong reducing power, reducing Fehling's solution in the cold. It is prepared by reducing diazo-benzene chloride with SnClj and HCl. It is sparingly soluble in water, but soluble in alcohol and ether. It is important as an exceed- ingly delicate test for aldehydes and ketones, combining wiih them to form a class of bodies known as hydrazones. Most of these compounds are solid and crystalline, and may easily be recognized. They are employed in the separation of ihe sugars from one another. (See Arts. 594-603.) 748. Hydracetin— Pyrodin — Acetyl-phenyl-hydrazin — CsHsNHNHCHjCO, is prepared by heating phenylhydrazin and acetic anhydride, dissolving the product in boiling water and crystallizing. It is also prepared by the prolonged action of glacial acetic acid on phenylhydrazin, distilling with an excess of acid and crystallizing. It occurs as a white, tasteless, odor- less, crystalline powdtr, melting at 128° C. (262.4° F.) and soluble in 50 parts of water. When boiled with HCl it splits up into acetic acid and phenylhydrjzin hydrochlorate. Like phen- acetin and methacetin, it forms a colorless solution with HjSOi, which turns red by the addition of HNO3. It is a strong reduc- ing agent, reducing silver nitrate, AgNOj, and gold chloride, 432 MEDICAL CHEMISTRY. AuClj, precipitating the metals. It has been recommended as an antipyretic and for external use in skin diseases. It is a well marked blood poison, destroying the blood corpuscles. For this reason care must be exercised in its use. ( C6.H4 — O — CjHj 749. Phenacetin — Acetphenetidin — N ] C.1H3O . . As will be seen from a comparison of the formulae, this compound is closely related to acetanilid. It is prepared from sodium para-nitro-phenol by converting it into para-nitro-phenetol by the action of ethyl iodide. This is reduced to paraphenetidin, which on prolonged boiling with glacial acetic acid, yields phenacetin. Phenacetin occurs as colorless, tasteless, inodorous, glistening, scaly crystals, melting at 135° C. (275° F.). It is sparingly soluble in cold water, but soluble in about 70 parts of hot water. It is more soluble in alcohol. It is very much employed in medicine as an antipyretic, and for the relief of pain, in doses up to 15 grs. It has slight, if any, toxic properties. It may be identified by the production of a deep red color with chromic acid, when added to the drug dissolved in dilute hydrochloric acid. Its freedom from acetanilid may be proven if its aqueous solution does not become turbid on addition of Br water. Sul- phuric acid should dissolve it without color. Heated with free access of air, it burns off, leaving no residue. 750. Antipyrin— Phenazone (B.P.) — Phenyl-dimethyl- SCOCH NCH rCH ' ^^ prepared by the action of phenylhydrazin and acetylactic acid by which phenylhydrazin acetylactate is formed. By the action of heat, this separates into ethyl alcohol and phenyl-methyl-pyrazolon. By warming this compound with methyl iodide, a dimethyl phenylpyrazolon is produced. Antipyrin forms small, lustrous, rhombic needles, or plates, which are odorless and have a bitter taste. It melts at 113° C. (235° F.) and is readily soluble in water, alcohol and chloroform, but is less soluble in ether. On exposure to the air it. takes up a small quantity of water and thus melts at a lower temperature. It is decomposed by strong NaOH solution, the base separating as a milky oil speedily collecting into oil globules. The aqueous solution exhibits no alkaline reaction with litmus paper, but does so with methyl orange. It may be quantitatively estimated by titration in an aqueous or alcoholic solution with methyl orange as an indicator. It is a strong univalent base. Its salts, most of which are soluble, do not crystallize. Several of these salts have been used in medicine. The benzoate, obtained by the addition DERIVATIVES OF ANILIN. 433 of antipyrin to a boiling solution of benzoic acid, has a pungent taste and slight odor of benzoic acid. It is slightly soluble in water, but freely so in alcohol and ether. The salicylate, or salipyrin, is the only one of these salts which has been used in medicine. It is prepared by the direct combination of antipyrin and salicylic acid. It occurs as a white, coarsely crystallized, odorless powder, with a harsh sweetish taste, almost insoluble in water, but readily soluble in alcohol, from which it crystallizes in hexagonal tables. It has been recommended as a remedy in the treatment of rheumatism. It also forms compounds with phenol. Phenopyrin is prepared from equal parts of crystallized phenol and antipyrin. Pyrogallopyrin, naphthopyriivand resOK^- rin are compounds of pyrogallic acid, naphthol, and resorcin, respectively, with antipyriji. Antipyrin forms several compounds with chloral. One of these has been used in medicine under the name of hypnal. lodopyrin is a substitution product of anti- pyrin, in which one atom of H of the benzene nucleus has been replaced by iodine. The formula is QHiI — N ■< »jpTT pptr It occurs as a tasteless, colorless, crystalline powder. It is slightly soluble in cold, and readily in hot water. Tests. — Antipyrin gives a delicate and characteristic blood-red coloration with Fe2Cl5. The reaclion is distinct in a solution of i in 2000. The red color is discharged by HCl. This reaction is given at once by urine contain- ing antipyrin. On cautiously adding a solution of iodine in potassium iodide to a solution of antipyriii, a permanent brick-red precipitate is produced, per- ceptible in a solution containing I part in 20,000. Antipyrin gives a white precipitate vvith Millon's reagent. When heated with strong HNO3 until re- action commences, and the liquid then allowed to cool, a purple color is pro- duced. On adding water a violet precipitate is thrown down. This reaction is probably due to the formation of nitrous acid, which gives with antipyrin a beautiful green coloration, perceptible in I part in 20,000. When the liquid is heated it becomes purple-red. In strong solutions, small green needle-shaped crystals occur. These consist of iso-nitroso antipyrin, CjjHj.NjOj. Ni- troso antipyrin explodes when heated to about 200° C. (392 F.). It is said to be poisonous. A green coloration of antipyrin with nitrous acid thus be- comes a delicate test, but is common to all pyrazolons. With spirit of nitrous ether, antipyrin rapidly acquires a dark green color, and green needles of ni- troso antipyrin, separate. This green compound has been claimed to be poi- sonous, but experiments upon rabbits and dogs seem to show that 4 grains produce no perceptible poisonous effects. From the variety of reactions which antipyrin may undergo, there are a considerable number of medicines which are incompatible with it. It should, therefore, generally be given by itself, and hot mixed with other substances. 37 434 MEDICAL CHEMISTRY. ARTIFICIAL ORGANIC BASES. 751. These are compounds which are generally derived from coal tar, and probably are closely related to the amins. Bases similar to, and isomeric with a few of these, have been obtained by the distillation of some of the alkaloids with potash. For exam- ple : quinolin, or chinolin, CaHjN, has been prepared both from the alkaloids and from coal tar. It has been prepared by the action of HjSOj and nitrobenzene upon anilin and glycerin. The mixture is heated to 130° C. (266° F.), the lamp removed when reaction begins, and then heated again for three hours, and finally distilled with lime. When quinolin distils over with anilin, from which it may be separated by fractional distillation. It may also be obtained by distilling quinine with an alkali. When pure, quinolin, or chinolin, is a colorless liquid, with characteristic aromatic pungent odor, of sp. gr. 1.084. It is freely soluble in alcohol, ether, chloroform, and hot water. It is insoluble, or only slightly soluble, in cold water. It has been employed as an antiseptic and antizymotic, and to a slight extent as an antipyretic. For internal use a tartrate has been recom- mended. When quinolin is treated with H2SO4 it yields a sul- phonic acid. This, treated with nascent H, and the resulting product with methyl iodide, the body C9H,oO(OCH3) or QoHis NO, methyloxychinolin, is produced. This substance closely resembles quinine, C20H24N2O2. Its hydrochlorate is used medi- cinally under the name of kairin, as a substitiite for quinine. The corresponding ethyl derivative is also employed for the same purpose. The kairins act as powerful antipyretics, but their use has been attended with unpleasant after effects. 752. Thallin is an antipyretic remedy, metameric with kairin, tetra-hydrochin-anisol. Its constitution is as follows : CeHj NHCH ^"^ CeHioNOCHs- It is prepared by heating paramidoanisol and paranitroanisol with glycerin and H2SO4, and reducing the product with nascent H. It is a strong base, crys- tallizing in colorless prisms, having a bitter, saline, pungent taste. It melts at 42 C. (107.6° F.), and is insoluble in water, but is readily so in alcohol, ether, chloroform, and benzene. Thallin forms a series of well-defined salts. A sulphate and a tartrate have been used in medicine. The former is a yellowish white, crystalline powder, of a saline, bitter and spicy taste.' It is soluble in 7 parts of cold water. It is also soluble in alcohol, but almost insoluble in chloroform and ether. With iodine its THE PYRIDIN BASES. 435 solutions give a brown precipitate, with tannic acid white, with Nessler's reagent lemon-yellow, with Fe^Cle an emerald green. The tartrate closely resembles the sulphate in most of its proper- ties. These compounds are blood poisons, i. e., they disintegrate the red-blood corpuscles. THE PYRIDIN BASES, 753. These artificial bases are produced by the decomposition of bone gelatin, or ossein, in the destructive distillation of bones. They form a series of homologous bases which have received the name of pyridin bases. Some of them have also been found in coal-tar. They are liquids of a disagreeable, pungent, tarry odor, and belong to the tertiary monamins. They may be ex- tracted from the oflFensive oil known as Dippel's oil, obtained from the distillation of bones. By the addition of, or by shak- ing the oil with H2SO4, sulphates of the bases are produced which dissolve in water. The bases may be separated again on adding potash or soda. They are separated from each other by frac- tional distillation. The pyridin bases are often present in com- mercial ammonia. Their names are as follows: — Boiling points. Boiling points. Pyrid[n, C5H5N, 1 15° C. (239° F.). Collidin. CjHuN, 170° C. (338° F.). Picolin, CjHjN, 133° C. (271° F.). Parvolin, CgHijN, 188° C. (370.4° F.). Leutid n, CjH^N, 15;° C. (309° F.). Coridin, C,(,H,5N, 211° C. (411.8° F.). Rabidin, CnH^N, 230° C. (4^6° F.). Viridin, Ci^HijN, 251° C. (483.8° F.). 754. Pyridin is obtained from Dippel's oil, and is also ob- tained synthetically from piperidin, which is itself derived from black and white pepper. It may be prepared synthetically by a number of other reactions. It is a colorless liquid with a tarry odor and pungent taste. It boils at 115° C. (239° F. ), and has a sp. gr-. of .9858. It is raiscible with water in all proportions, and is hygroscopic. It forms salts with acids by direct addition, like the alkaloids; and, indeed, many of the alkaloids are be- lieved to be salts of this base. It has been employed in medi- cine in 3- to 4-drop doses as a stimulant in heart disease. It has been used as a local application in diphtheria and, by evapo- ration into the air, in the treatment of asthma. For medicinal uses it should not be altered by exposure to light. Pyridin bases occur in tobacco smoke. 755. Pyrrol, QHjN, is a weak liquid base occurring in coal tar and in Dippel's oil, from which it may be extracted by sulphuric 43^ MEDICAL CHEMISTRY. acid and distilling from the sulphate with a stronger base. It possesses an odor similar to that of chloroform. By the action of the ethereal salts of iodine upon pyrrol a tetra-iodo-pyrrol is obtained, C4I4NH. This compound is used in medicine under the name of iodol. 756. Iodol occurs as a grayish-brown, odorless, tasteless powder. It is of a light yellow color when pure, and is more or less crystalline. It decomposes between 140° and 150° C. (284° and 302° F.) and evolves iodine vapors. It is soluble in alcohol and ether but is sparingly so in water. AMIDO-ACIDS, OR ACID AMIDS, AND THEIR DERIVATIVES. 757. These compounds may be regarded as araids formed by re- placing a part of the hydrogen of a radical of an organic acid with amidogen. They exhibit both acid and basic properties. Many of these compounds and their derivatives exist in the human body. The simplest representative of the amido-acids is Gly- cocol— Glycocin, or Amido-acetic Acid — N < p|j COOH It is prepared by heating monochloracetic acid with ammonia, CHjClCOjH + 2NH3 = CHjNHjCOOH -|- NH4CI or boiling glue with alkalies or acids. HjSOi is added to the mass to separate the alkali as a sulphate. It is then evaporated to dryness, and the residue exhausted with alcohol and allowed to crystallize. It may also be prepared from ox bile and from uric acid, or by the action of formaldehyde upon a solution of hydrocyanic acid. CH^O + HCN + H^O = NHjCH^COOH. It appears as large colorless, transparent crystals, having a sweet taste and melting at 170° C. (338° F.) and decomposing at higher temperatures. It is sparingly soluble in cold water but more soluble in warm. It is insoluble in alcohol and ether and has an acid reaction. It combines with acids to form crystalline salts, which are generally decomposed by boiling water or by treatment with strong acids. When heated under pressure with benzoic acid, it forms hippuric acid. Its acid function is more marked than its basic. It expels carbonic and acetic acids from many of their salts. With ferric chloride, FejCIs, it gives an intense red colored solution, discharged by acids and returning AMIDO ACIDS AND THEIR DERIVATIVES. 437 on neutralization. With phenol and NaOH solution, it gives a blue color similar to that given by ammonia. It gives a charac- teristic copper salt like most of the amido-acids. This salt serves for the separation of these acids, Glycocol does not occur in the free state in the animal body, but enters into the composition of several important substances, more especially hippuric and glycocholic acids. It exists in combination in the gelatins, and with cholic acid as sodium gylcocholate in the bile. 758. Hippuric Acid — Benzamidacetic Acid — /COCeH, N — CjHjO.OH. This acid is found in the urine of herbivorous \H animals, and in small quantity in human urine.. When benzoic acid or oil of bitter almonds is taken internally, hippuric acid appears in the urine. It is generally,prepared by evaporating the urine of the cow or horse to one-tenth its volume, and precipi- tating with hydrochloric acid. It forms large, rhombic prisms, soluble in hot but sparingly in cold water; soluble in alcohol, but not in ether. The hippurates resemble the benzcates. 759. Methyl-glycocol or Sarcosin, N ■{ CH3 is (.CH.COOH found only in combination in the human body. It is of some interest as having been employed in experiments to determine the origin of urea in the body. It combines with cyanamid to form creatin. It therefore, enters into the composition of creatin. p TT SO2OH, occurs in traces in the juice of muscles and of the lung. It is known chiefly as a constituent of taurocholic acid, one of the characteristic biliary acids, especially of the carnivora. It crys- tallizes in colorless, four or six-sided prisms. It is readily sol- uble in water, less so in alcohol. Its solutions are neutral. It is a very stable compound, resisting a temperature of less than 240° C. (464° F.) and is not decomposed by dilute alkalies or acids even on boiling. The metallic salts do not precipitate it. It may be prepared from ox bile by boiling for several hours with dilute HCi. A resinous scum separates, and the bile acids are then precipitated from the liquid with lead acetate, the ex- cess of lead being removed with HjS. The filtrate from the PbS is concentrated and set aside to crystallize. It is purified by recrystaliization. When taurin is introduced into the ali- 438 MEDICAL CHEMISTRY. mentary canal, the larger part appears in the urine in combina- tion with carbamic acid as tauro-carbamic acid. When injected subcutaneously, it is largely excreted in an unaltered form. 761. Creatin — Methylguanidinacetic Acid — (— H ,N(CH3).CH;.C00H N ^ = C( =CiH9N302.— When sarcosin (. ^NH, is treated with cyanamid, creatin is produced. When cyan- amid is treated with boiling ba.ryta water it takes up a molecule of water and forms urea. CNNH2 + HjO = CO(NHj)j Cyanamid. . Urea. When creatin .is similarly treated, it yields sarcosin and urea, showing the relation between urea and creatin, which body is probably one of the sources of urea in the human body. Creatin occurs characteristically in the muscles and hence in meat extracts. The amount is variable but may be taken as from 0.2 to 0.3 per cent of the weight of the muscle. It is also found in nervous tissues and in several other tissues of the body. It may also be found in the urine, where it is believed to b^ derived from creatinin. Creatin, when pure, occurs in white, opaque, colorless, transparent crystals. It is soluble in 75 parts of water, slightly soluble in alcohol and insoluble in ether. Its solutions are neutral in reaction. Creatin is a weak base, form- ing crystalline compounds with some of the acids. It is most easily prepared from extract of beef, which is dissolved in water, precipitated with basic acetate of lead, filtered, and the lead separated from the filtrate with H2S, concentrated at a moderate temperature to a syrup, and set aside to crystallize. As stated above, creatin may easily be derived from creatinin, and the reverse. Creatin very readily loses a molecule of H2O and thus becomes Creatinin, CjHjNsO. It occurs normally as a constant constituent of the urine, varying in amount from 0.5 to 4.9 grms. per day, according to the amount of meat eaten. It crystallizes in colorless prisms or tables according to the condi- tion in which it is crystallized. It frequently assumes the pecu- liar whetstone shape of uric acid crystals. It is readily soluble in cold water, and alcohol, but is scarcely soluble in ether. Its solutions are usually alkaline and it acts as a powerful base, forming compounds with the acids and salts which crystallize well. It is precipitated from its solutions with ZnClj in the form of a crystalline precipitate or warty lumps of aggre- AMIDO-ACIDS AND THEIR DERIVATIVES. 439 gated crystals. This compound is formed whenever the solutions are brought together in a neutral and somewhat concentrated form. The addition of alcohol to the solution renders the pre- cipitate more complete. This compound with ZnCIj is em- ployed as a characteristic test for creatinin. 762. Leucin — Amido-caproic Acid, — QHisNOj, is a prg- duct of the decomposition of proteids and gelatin by either boil- ing acids, caustic alkalies, pancreatic digestion, or putrefactive fermentation. It occurs normally in variable amounts in the pan- creas, spleen, thymus, thyroid, liver, and salivary glands, also in plants, such as bulbs, tubers, and seeds, where reserved material is stored. It is most easily prepared by the pancreatic digestion of proteids, when it is produced in quantities of from 8 to ic per cent, of the proteid digested, and is then, always accom- panied by tyrosin. It sometimes occurs in the urine, par- ticularly in cases of acute yellow atrophy of the liver, although it does not always occur in this disease. Leucin forms yellow brown spheres consisting of masses of needle-shaped crystals, soluble in water, slightly soluble in alcohol, and insoluble in ether. Under the microscope the spheres resemble fat globules. When pure it forms very thin, white,- glistening crystals. Leucin is very soluble in the presence of acids and alkalies, the acid solution being laevorotatory, the alkaline solution being dextrorotatory. When heated, leucin decomposes into COj and amylamin, CeHijNO, = CO, -f CjH.iNH,. With HI it gives caproic acid and ammonia, C^H^jNO, -1- 2HI = CgHiA + NH3. With H2SO4 it gives ammonia, NH3, and valerianic acid. With potassium permanganate it gives oxalic acid, carbonic acid, valerianic acid, and ammonia.. It is probable that similar decom- positions occur in the human body. It is probably one of the intermediate products in the formation of urea. 763. Tyrosin — Amido-oxy-phenyl-propionic Acid. — Propionic acid has the formula CsHsO.^. Amido-propionic acid has the formula C3H5NH2O2. Oxy-propionic acid has the for- mula C3H5(C6H40H)0,i. If another H in this formula be re- placed by NH2 we get OH.QHjCNHOCOOH, which is the formula of tyrosin. Tyrosin always accompanies leucin, though less in amount, as a product of the pancreatic digestion of proteids, but not of gelatin. It is also a product of the putre- 44° MEDICAL CHEMISTRY. factive decomposition of proteids and gelatin, as well as of the action of boiling mineral acids and alkalies. It is found normally in the pancreas and some other tissues. It occurs in the urine, together with leucin, in phosphorus poisoning, and certain diseases of the liver, especially in yellow atrophy. It is also present, along with leucin, in many plant tissues. Tyrosin crystallizes in very fine needles, usually collected together in feathery masses. The crystals are colorless, tasteless, and odor- less. They are sparingly soluble in cold water, almost insoluble in alcohol, and quite insoluble in ether. They are readily solu- ble in acids and alkalies. It may be obtained, along with leu- cin, by boiling horn shavings with H2SO4 (5 of acid to 13 of water). The HjSOi is separated with lime, and the filtrate from the CaSOi, evaporated down and crystallized. It is purified by recrystallizing from boiling water. It is separated from leucin by repeated crystallization, faking advantage of the great solu- bility of leucin and the slight solubility of tyrosin. When heated with Millon's reagent, tyrosin yields a brilliant crimson or pink coloration. If moistened on a watch glass with strong H2SO4 and warmed for five or ten minutes on a water-bath, it forms tyrosin sulphonic acid and turns pink. 764. Cystin — Amido-sulpho-lactic Acid— CsHtNSOs, = C3H4(HS)(NH2)03. — It is a constituent of rare urinary calculi occurring in men and dogs. It may also occur in renal concre- tions. It is occasionally found in the urine, from which it separates as a sediment on standing. It is prepared from this sediment, or from a cystic calculus, by Solution in ammonia and crystallizing. It crystallizes in regular six-sided tables, characteristic in appear- ance. It is insoluble in ether, alcohol, and water, but is readily soluble in NH4OH. When boiled with NaOH, a sulphide of sodium is obtained, which gives a dark stain on silver coin. Aspartic Apid, C4H,N04, is amido-succinic acid. It is obtained from asparagin, which occurs in plants. Glutamic Acid, C5H9NO4, is amido-glutaric acid. 765. Carbamic Acid, or amido-formic acid, NHjCO.OH, is not known in the free stale. These three acids are products of the decomposition of proteids. Carbamic acid is of interest on account of the important part it is supposed to play in the formation of urea in the animal body. It maybe formed by the direct union of dry NH3 and COj, a second molecule of NH3 uniting with it, at the same time, to form the ammonium car- bamate, thus: 2NH3 -I- CO, = NHjCCOjNHj). Ammonium carbamate. AMIDOACIDS AND THEIR DERIVATIVES. 44.1 By simple dehydration this salt yields urea, NH^NHCOj = HjO. + (NHj)2CO. Urea. Ammoniutn carbamate is extremely soluble in water, in which solution it is gradually converted into the carbonate. When it is heated to 60° C. (140° F.) it decomposes into NH3 and CO2, but when heated under pressure at 130° to 140° C. (266° to 284° F.) it yields urea. 766. Urea — Carbamid — (NH2)2CO, is the chief nitrogenous constituent of urine. The urine of birds contains a small quan- tity. When on a meat diet the average normal human urine con- tains from 2.5 to 3.5 per cent., the average daily excretion being about 30 grms. It is also found in minute quantities in normal blood, serous fluids, lymph, perspiration, and the aqueous humor. It is also met with in the liver. It crystallizes from a concen- trated solution in the form of long, thin, glittering, needle- shaped crystals. If deposited slowly it forms four-sided prisms with pyramidal ends. They are anhydrous. Urea is very soluble in cold water, less soluble in alcohol, and insoluble in pure ether and petroleum ether. It possesses a somewhat bitter, cooling taste, resembling that of saltpetre. It may be prepared from the urine by concentrating to a syrup, extracting the resi- due with boiling alcohol, and concentrating the alcoholic extract by slow, spontaneous evaporation, until the urea crystallizes out. It is then purified by recrystallization from alcohol, decolorizing with charcoal if necessary. Or the urea may be pre- cipitated as nitrate by the addition of nitric acid to the concen- trated and cooled urine. The nitrate is then decomposed by suspending it in water and adding barium carbonate. The urea is then crystallized as before. It may be prepared synthetically in several ways ; the most convenient method is by mixing equal quantities of ammonium sulphate and potassium cyanate. The ammonium cyanate thus formed, on being evaporated to dryness, is transformed into urea, NH^CON = NH.CONH^. This synthesis was performed by Wohler in 1828, and was the first substance of animal origin that was artificially prepared, and maybe regarded as the beginning of synthetic chemistry. Urea forms well-defined salts with both bases and acids. The nitrate, (NHj)2CO.HNOs, is easily obtained from urine by evaporating it down to about one-fourth its volume, adding pure nitric acid, and keeping the solution cool. The crystals will separate in a few minutes in the form of rhombic tables, frequently 38 442 MEDICAL CHEMISTRY. aggregated into masses. The crystals are only slightly soluble in HNO3 or alcohol, but are soluble in water. The oxylate of urea crystallizes out in rhombic tables, closely resembling those of the nitrate, and under the same conditions. Of the many salts which urea forms with bases and salts, those which it forms with mercuric nitrate are important, because this salt is used as a reagent for the quantitative estimation of urea. When a solution of mercuric nitrate is added to one of urea, a precipitate is formed as long as urea remains in solution. Urea may be heated dry at about 1 20° C. (248° F.) without decomposing, but at about 132.6° C. (271° F.) it gives off ammonia, and at 150° C. (302° F.) it is convened largely into biuret. 2(NH2)2CO =- NH, CONHCONHi! -f NH3. On heating to a higher temperature (about 200° C. (392° F.) ) it is largely converted into cyanuric acid. When boiled in water with strong H2SO4 or alkalies, it gradually absorbs two molecules of water, and is converted into carbonic acid and ammonia. A similar change is produced under the influence of certain micro-organ ii-ms, which are found in urine undergoing the alkaline fermentation. The best known of these is'the micrococcus ureae, from which a soluble hydrolytic enzyme may be extracted. The most prolific source of the urea enzyme is the mucous urine passed in inflammatory diseases of the bladder. In these cases the enzyme seems to be associated with mucin, and is presumably secreted by the mucous mem- brane. This explains why, in all inflammatory diseases of the bladder, the urine so readily undergoes the alkaline fermentation. When treated with nitrous acid, urea undergoes decomposition into CO2, N and H^O. A similar decomposition is obtained by the action of NaClO or NaOBr. (NHj )jCO + 3NaBrO = 3NaBr + CO, + N, + 2HjO. Since the volume of N evolved is constant for a given weight of urea, this reaction is made the basis for the quantitative estima- tion of urea in urine. It may be detected in solution by evapo- ration with nitric acid or oxalic acid, and examining the crystals under a lens. Mercuric nitrate should give a precipitate in the absence of sodium chloride in excess. Yellow nitrous acid should produce an effervescence. With furfurol and hydro- chloric acid, in not too dilute solution, urea gives a play of colors passing rapidly from yellow through green, blue, violet, and finally purple. The estimation of urea will be considered in a chapter on the examination of urine. The origin of urea in the body has been the subject of a great AMIDO-ACIDS AND THEIR DERIVATIVES. 443 deal of discussion and experiment. There is no doubt that its origin is in the decomposition of muscular and other tissues. The immediate antecedents of urea are not so clearly known. It is supposed, however, that creatin, creatinin, glycin, leucin,and other members of the amido-acid class are the intermediate pro- ducts between the proteids on the one hand, and urea on the other. The seat of the changes of these araids into urea is sup- posed to be largely in the liver. In the case of leucin, the evi- dence of this is direct, and there is increasing evidence that this organ is largely concerned in the synthetic changes which lead to the formation of urea in mammals, and of uric acid in birds. Schroeder has shown that the conversion of (NH4)2COa into urea occurs in the liver, and Minkowski has shown a similar relation to the formation of uric acid in birds. When the liver is dis- eased, leucin and tyrosin escape conversion, and appear in the urine, and at the same time there is a marked diminution in the excretion of urea. When urea is given to birds it appears externall)?- as uric acid. These changes do not occur after extir- pating the liver. NH— CO 767. Uric Acid, CsH.N.Os, CO c— nh\ , is a common con- NH— C— NH/ stituent of urine in birds and reptiles, and occurs sparingly in this secretion in men and most mammals. It is present also in the spleen, and traces have been found in various other tissues. It sometimes occurs as a concretion or calculus in the bladder an^ kidneys. In gout, accumulations of uric acid salts deposit in certain tissues, especially about the joints. When pure, it is a colorless, crystalline, tasteless powder without odor. Its crys- talline form is very variable, the shape of the crystals depending upon the condition of the fluid at the time of crystallization. To the naked eye, these crystals, when separated from the urine, always appear reddish or yellow in color, but under the micro- scope they appear to be colored yellow throughout. Uric acid is remarkably insoluble in water, one part requiring 15,000 parts of cold water and 1600 parts ^f boiling water to effect solution. It is insoluble in ether and alcohol. H2SO4 dissolves it in the cold without decomposition, as do also many of the alkaline salts and the caustic alkalies. Ammonia, however, does not dis- solve it. It is fairly soluble in glycerin and to some extent in solutions of lithium carbonate. It occurs in the urine also in the form of the neutral and acid urates of sodium, the latter of which appears as a sediment, and is frequently spoken of as 444 MEDICAL CHEMISTRY. lithates, and the term lithic acid is sometimes employed- instead of uric acid. In urine that has undergone alkaline fer- mentation, ammonium urate will frequently be found, occurring in the form of small, brown, nearly opaque balls with radiating spicules easily seen with a microscope of moderate power. The' amount of uric acid in human urine is very small. Pathologi- cally it is sometimes found in considerable quantities. It may be prepared from human urine by adding from 2 to 3 per cent, of strong HCl, and allowing the solution to stand for 24 hours in a cool place. The crystals form on the sides of the containing vessel and may be filtered out. It is usually prepared from guano or snake excrement. From the latter it is obtained by' boiling with one part of KOH to 20 of water as long as NH3 is evolved, when the solution is filtered. On cooling, CO is passed through the solution, when the acid urate of potassium precipitates. This salt is dissolved in KOH, and carefully neutralized with HCl, when the uric acid precipitates. Detection of Uric Acid. — The acid is usually detected in the urine by the microscopic appearance of its crystals. It occurs in a variety of forms, all of which are more or less colored when separated from the urine, and ap- pear as rhombic plates, or in whetstone shaped crystals, occasionally in the form of dumb-bells, and often in groups embedded in one another. It may be detected also by evaporating the suspected solution nearly to dryness, cool- ing, adding a few drops of HNO3, and evaporating to complete dryness on a water bath. The residue thus obtained is moistened with ammonia, when a brilliant, reddish-purple color is developed if uric acid be present. This color deepens on warming, while a similar color obtained by guano does not ; thus the two substances are distinguished. The test depends on the formation of murexid, an ammonium salt of purpuric acid, and is known as the Murexid test, SchiiTs reaction is obtained by dissolving the substance in Na2COs, and bringing a drop of the solution in contact with a solution of AgNOj, upon a piece of filter paper, when a yellow or black stain, due to the reduction of the nitrate of silver, is at once obtained. When heated with Fehling's fluid, uric acid reduces the copper with the production of a grayish precipitate of cuprous urate. Uric acid is estimated quantitatively with some difficulty. The best method is that of Haycraft. According to this method the uric acid is precipitated by an ammoniacal solution of AgNO,, in the presence of ammonium magnesium chloride. The precipi- tate contains one atom of silver to one molecule of uric acid. The precipitate is filtered out, dissolved in HNO3, and the silver estimated volumetrically with a standard solution of potassium sulphocyanate, using a few drops of ferric alum as an indicator. Uric acid contains the nucleus of two molecules of urea and is AMIDO-ACIDS AND THEIR DERIVATIVES. 445 •sometimes regarded as a diureid. In some of its decompositions it yields urea, as one of its products. For this reason it was for- merly believed to be one of the antecedents of urea, and to be a stage in the oxidation of nitrogenous waste short of that neces- sary to produce urea. It occurs in increased amounts when, for any reason, the oxidation within the body is interfered with, as in diseases of the lungs, liver or skin, or in excessive partaking of nitrogenous food. It may be diminished in such cases by agents that will increase the oxidation in the blood and tissue^. By the oxidation of uric acid with nitric acid, it decomposes into a molecule of alloxan and one of urea. By fur- ther oxidation alloxan is converted into parabanic acid or oxal-ur.ea and CO2. C5H4NA + O -I- H,0 = QH,NA + (NH,)jCO. Uric acid. Alloxan. Urea. C,H,NA + O = C,H,N,03 + CO,. Alloxan. Parabanic acid or oxal-urea. When parabanic acid is heated with alkalies, it forms oxaluric acid, and this by prolonged boiling is converted into urea and oxalic acid. By oxidation with KzMnjOa, uric acid is decomposed into allantoin and COj. Allantoin with HNO3 gives urea as one of its decomposition products. 768. Oxaluric Acid, CaH^NjO^, occurs in minute traces in human urine, and. is a white crystalline powder, not very soluble in water. Its alkaline salts, however, are readily soluble. 769. Allantoin, C4H5N4O3, is a characteristic constituent of the allantoic fluid and of the amniotic fluid. It is also found in the urine of many animals for a short period after their birth. It is found in the urine after the internal administration of uric acid. It has been found also in vegetable tissues. It crystal- lizes in small, shining, colorless, hexagonal prisms, soluble in 160 parts of cold water, and insoluble in cold alcohol and ether. The alkalies dissolve it, forming salts. It gives no reactions which are sufficiently characteristic to admit of its de- tection in urine or other fluids. It must be separated from them and be obtained in the crystalline form. Allantoin has been ob- tained synthetically by heating together glyoxalic acid and urea. 770. Alloxan, CiH^NjOi. — This is another of the decom- position products of uric acid under mild oxidation. It has been found in the intestinal mucus in cases of diarrhoea. It crystallizes in colorless crystals, readily soluble in water. 446 MEDICAL CHEMISTRY. 771. Murexid— Ammonium Purpurate — C8H4(NH4)N508, ■ is produced by the oxidation of uric acid, alloxan, guanin and a number of other derivatives of uric acid, with subsequent treat- ment with NH+OH. It is an ammonium salt of a hypothetical acid which has not yet been isolated. It is of a brilliant reddish- purple color, and has before been referred to in the murexid test for uric acid. NH— CH 772. Xanthin, CO c— nh = CcHiNiOj, was first discovered ' \ I \ NH— C=N— CO in urinary calculi and called xanthic oxide. It is a normal, though scanty, constituent of urine, muscle, liver, spleen, thymus and brain substance. It occurs in large quantities together with hy- poxanthin in "extract of meat" and is also found in traces in certain vegetable tissues. . In nearly all cases it is accompanied by hypoxanthin. It may be prepared from extract of beef. When pure it is a colorless powder, almost insoluble in water, alcohol and ether, but it dissolves readily in dilute acids and alkalies, forming crystallizable compounds. NH— CH 773. Hypoxanthin— Sarcin — ch'' (!:-nh\ -Ct^tfifi, N — c=.n/ is closely related to xanthin and usually occurs with it in the tis- sues and fluids of the body. It is obtained from fluids or tissue extracts. A silver salt of xanthin and hypoxanthin is employed for their separation from fluids. Methylxanthin — Heteroxanthin — CeHeN^Oa, occurs in minute quantities in normal urine of man and dog along with xanthin, hypoxanthin and paraxanthin. Dimethlyxanthin — Paraxanthin — CiHgNiOj, is an isomer of theobromine. As stated above, it occurs in very small amounts in urine, and is closely related to the above compounds. Its physiological action, when administered internally, is identical with that of theobromine. 774. Carnin, QHsNiOa, is another base closely allied in com- position to the above compounds. It occurs in extract of meat, of which it forms about one per cent. It may be prepared by pre- cipitating extract of meat with Ba02H2 water, avoiding excess. The precipitate is filtered out, and the carnin precipitated from the filtrate with basic lead acetate. The precipitated lead salt is suspended in hot water, and the lead separated with HjS ; the filtrate is concentrated and the carnin crystallized out. AMIDO-ACIDS AND THEIR DERIVATIVES. 447 It separates in white masses composed of very irregular crystals, readily soluble in hot water, slightly soluble in cold water, and insoluble in alcohol and ether. It unites with acids and salts to form crystalline compounds. Carnin may be converted into hypoxanthin by treatment with chlorine or HNO3, or still more readily by bromine. NH— CH 775. Adenin, ch c— nh\ = C5H5N5, is another base "^ 'si c-nh N— C— N / closely related to xanthin in composition, and was first obtained from the pancreatic tissue. It is said to have been found in the urine. A number of the foregoing compounds, as will be seen, occur in the extract of meat. It has been proved that the chief virtue of extract of meat is in the stimulant properties of these bases. 776. Guanin, C5H5N5O, is found in Peruvian guano and in small quantities in the pancreas, liver, muscle extract, and many of the products of the action of acids upon nuclein. It may also occur in the urine. It is a white, amorphous powder, insoluble in water, alcohol, ether and ammonia. 777. Guanidin, CN3H5, is one of the oxidation products of guanin. It does not occur in the free state m any of the normal tissues or fluids of the body, but has been obtained by the oxida- tion of proteids. It may be made to yield urea by treatment with hot dilute H2SO4. It has also been obtained by synthesis. 778. Indol, CgHjN, occurs characteristically in the faeces, to which, with skatol,.it imparts their unpleasant odor. It is formed during the putrefactive decomposition of proteids, which usually occur, to a greater or less extent, in the alimentary canal. A part of the indol leaves the body by the urine as a potassium salt, or as indoxyl sulphuric acid. The remnant passes out with the faeces. It may be obtained, together with phenol and skatol, by acidulating and distilling the products of a somewhat prolonged, alkalme,4)utrefactive, pancreatic digestion of proteids. Indol passes over with the distillate, from which it is extr.acted by shaking with eiher, and is left as an oily liquid when the ether evaporates. It may also be prepared by heating most proteids with excess of KOH. Indol is a crystalline body soluble in boiling water, alcohol and ether. It may be detected as follows : — A strip of pine wood, moistened with HCl, is colored a bright crimson when dipped into an alcoholic solution of indol. The alcoholic solution turns red when treated with nitrous acid. Its aqueous solution gives a red precipitate with the same reagent. 448 ■ MEDICAL CHEMISTRY. 779. Skatol — Methylindol — C9H9N, occurs also in human faeces together with indol, being present in larger amounts than the latter. The conditions of its production are the same as those for indol, so that the two substances of cur mixed in the pro- ducts of putrefactive decomposition of proteidf, and of the action of caustic potash upon proteids at a high temperature. A portion of the skatol produced in the intestine is abforbed, oxidized, and appears in the urine as skatoxyl sulphuric acid. 780. Indoxyl-sulphuric Acid, CgHeNOSOaOH, is the indi- can frequently mentioned as occurring in the urine. This com- pound is not identical with the indican found in plants, which is a glucoside. It is in reality a sulphuric ether of indoxyl, CgHjNOH, a compound similar to phenol and cresol. Indican is increased in carnivorous animals, under a meat diet, but is not increased by the administration of gelatin. It is more plentiful in the urine of herbivora than of carnivora. Indoxyl sulphuric acid occurs in the urine combined mostly with potassium. When warmed with HCl it decomposes into indoxyl and acid potassium sulphate. CgHgNOSOjOK -f HjO = CjHjNOH -|- KHSO^. Potassium indoxyl sulphate. Indoxyl. Irdoxyl by oxidation is converted into indigo blue. 2CaHeNOH + 0, = C„H,„NA+ 2HjO. The formation of indigo blue is used in Jaffa's test for indican in the urine. The te.'t is applied as follows: — lo c. c. is mixed with an equal volume of strong HCl and 2 to 3 c. c. of chloroform. A Strong solution of chloride of lime is then added, drop by drop, shaking after the addition of each drop. If indican be present, the chloroform, on separating and standing, will be colored irore or Jess deeply blue, accoiding to the amount of indican present. Skatol alsooccuis in the urine. When Jafi^'s test for indican is applied to urine which contains skatoxyl compour.ds the urine turns red or violet on the addition of HCl, and bright crimson on the addition of HNO3. A similcr color is obtained if it is waimed with HCl and FejClji 781. Indigo Blue, Ci6H,oN202, is formed as above staled from indican, and gives rise to the blue color sometimes observed in sweat and urine. It may be obtained by slow formation from indican, in fine crystals insoluble in water, but slightly soluble in alcohol, ether, chloroform and benzene. Indican is soluble in strong H^SOi, forming two sulphonic acids. The sodium salts of these acids are soluble in water and, when mixed with sodium sulphate, constitute "indigo carmine" of commerce, AMIDO-ACIDS AND THEIR DERIVATIVES. 449 and, in the pure form of sulphindigolate of soda, is employed as a test for sugar in the urine. Indigo possesses a pure blue color, and leaves a red streak when diawn across a hard body. Treated with reducing agents in strongly alkaline solution it is reduced to indigo white ; on exposure to air the indigo white again becomes indigo blue. It thus proves a convenient reaction for the detection of indigo, or for reducing substances like dextrose. Biliary Acids. — The bile contains the sodium salts of two amido-acids and several acids derived from these by deccmpo- sition. The two acids contained in the bile are glycocholic and taurocholic acids. 782. Glycocholic Acid, C26HJ3NO6, occurs in bile as a sodium salt. The acid occurs in two foims, the one as fine crystalline needles, and the other as an amorphous resinous solid. It is monobasic. It is soluble in hydrochloric, sulphuric and acetic acids, without decomposition. Soluble in glycerin, slightly soluble in cold and readily in hot water. Very soluble in alcohol and insoluble in ether. When boiled with alkalies or mineral acids it splits up into cholic acid and glycocin, CjsH^NO^ + H,0 = C„H^„05 + QHjNH.O,. Cholic acid. Glycocin. 783. Taurocholic Acid, C26H45NSO,, occurs in small quan- tity in human bile, but in larger quantity in that of the carnivora. It is soluble in water and alcohol. With boiling alkaline or acid solutions, it forms cholic acid and taurin, C2H,NS03. The spontaneous decomposition of bile causes the same change. Both glycocholic and taurocholic acids form salts which have the power of dissolving cholesterin and of emulsifying fats. They also form insoluble compounds with the salts of the alka- loids and with peptone. These salts are soluble, however, in excess of the biliary salts. The taurocholate of morphine is crystallizable. The glycocholate of sodium exists in the bile, and may be prepared from fresh ox bile. They may be precipi- tated from neutral solutions by lead acetate, but the precipitate is soluble in an excess of the precipitant. -Tests for Biliary Acids. — To a solulion of the biliary acids add a few drops of a solution ol cane sugar (i to lo), and then strong sulphuric acid; A cherry red, followed by a deep purple violel color is produced. This test, known as Petlenkofer's, cannot be applitd to organic mixtures, as uiine, be- cause numerous other bodies give the same color. To apply it to such mixtures, evaporate to dryness, exhaust the residue with absolute alcohol, decolorize the solution with animal charcoal, evaporate to dryness, di.ssolve in water, and then test -as above. 43° MEDICAL CHEMISTRY. NATURAL ORGANIC BASES, OR ALKALOIDS. 784. Many plants, and especially those having medicinal and poisonous properties, contain basic principles, or compounds containing nitrogen, which are called alkaloids. Some are volatile, while others decompose when heated. Most of them resemble the amins or compound ammonias in properties, while some correspond more nearly to the ammonium compounds. Most alkaloids are sparingly soluble in water, more freely in alcohol, the solutions having an alkaline reaction and bitter taste. They combine directly with acids, like NH3, forming crystalline salts, which are generally soluble in water. Their hydrochlorates form crystalline double salts with the chlorides of gold, platinum, mercury, etc. Most of them are precipitated by solutions of tannin, the double iodide of potassium and mercury, double iodide of cadmium and bismuth, phosphomolybdic, phosphoantimonic, phosphotungstic, and picric acids, and by a solution of iodine in potassium iodide or hydriodic acid. These reagents are, therefore, used to precipitate the alkaloids from other substances found with them. By ti-eating these precipitates with an alkaline hydroxide the bases are separated. PROPERTIES OF THE NATURAL ALKALOIDS. 785. The true vegetable alkaloids, or plant bases are very nu- merous. Many of them are imperfectly known, while others have been studied very completely. The alkaloids are generally found in all parts of plants, though in some cases they are restricted to certain portions. The vegetable alkaloids are in most cases intensely poisonous, while in others, as the alkaloids of coffee, cocoa, and cinchona, they produce characteristic physiological effects but are not actively poisonous. They generally have a bitter taste. The most of them are solid at ordinary tempera- tures. The non-oxygenized, volatile bases are liquid. The al- kaloids are alkaline in reaction. They unite with acids to per- fect neutrality and form well-defined crystallizable salts. In some cases the basic character is feebly marked, when no acids exist, and even the salts with the stronger acids are easily decom- posed. As a rule the vegetable alkaloids, except the volatile bases, are sparingly soluble in water and are, therefore, usually precipitated by the addition of solution of a strong base to a solution of their salts. They are nearly all readily dissolved by alcohol, except rhoeadine and pseudomorphine. PROPERTIES OF THE NATURAL ALKALOIDS. 45 1 The salts of the alkaloids are generally more soluble in water than the bases themselves and, as a rule, dissolve on the addition of alcohol. As a rule the alkaloids form a class of double salts, /. e., chloroplatinates, mercuro-iodides, etc., with platinic chloride and mercuric iodide. Immiscible solvents, such as chloroform, amyl alcohol, ether, benzene, bisulphide of carbon, differ con- siderably in their solvent powers of alkaloids and alkaloidal salts. 786. Nomenclature of Alkaloids. — While there is a great deal in favor of the reform in spelling of many chemical terms, and while we have adopted the practice of dropping the final e in the artificial bases and compound ammonias, we shall retain the final e in the spelling of the names of the alkaloids. The alkaloids, being very active and frequently poisonous substances, should be sharply distinguished from the glucosides and bitter principles, and the very numerous synthetical substances recently introduced into medicine. This distinction, which has existed for years, and which is -well fixed in the minds of a large proportion of the physicians and pharmacists of all English speaking countries will be preserved by retaining the final e. Thus we shall use mor- phine instead of morphin, and quinine instead of quinin. 787. Reagents for Precipitating Alkaloids. — Alkaloids as a class give precipitates with a considerable number of re- agents, especially the compounds of the heavy metals. Of these precipitants the most generally used are a solution of I in KI, a solution of phosphomolybdic acid (Sonnenschein's reagent') and a solution of double iodide of mercury and potassium (Mayer's reagent). With the exception of tannin, which should be em- ployed in neutral or slightly alkaline solution, the precipitants of alkaloids are usually added to the solution slightly acidulated with HzSOi or acetic acid. Mayer's Reagent is made by dissolving 13.546 grms. of mercuric chloride and 49 8 grms. potassium iodide in 1000 c. c. of water. This solution precipi- tates all alkaloids, forming white or yellowish-white crystalline compounds of definite composition, for which reason this solution is used for volumetric esti- mation of alkaloids. Phosphomolybdic Acid, mentioned above as a reagent for alkaloids, is prepared asibllows; — Dissolve 15 grms. ammonium molybdate in a little ammonia water and add water to make 100 c. c. This solution is poured into 100 c. c. of strong nitric acid, and this mixture is added to warm 5 per cent, solution of solium phosphate, as long as a precipitate forms. The precipitate is collected on a filter, washed, dissolved in a very little of NaOH sotudon, and evaporated to dryness, or heated, until all NH, escapes. The residue is to be dissolved in about 10 parts of water, anl enough HNO3 added to redis- 452 MEDICAL CHEMTSTRY. solve the precipitate which at first forms. This reagent gives precipitates not only with alkaloids, but also with salts of ammcnium and potassium. . Both of these reagents, while being dtlicaie tests (or alkaloids, precipitate albuminous and other matter not alkaloidal in nature. Picric Acid is employed as a saturated aqueous folution. It is very suitable for precipitating the cinchona bases, emetine, berberine and veratriiie. Iodine dissolved in a solution of potassium iodide (Wagner's reagent) yields reddish or red-brown precipitates with nearly all alkaloids, even in very dilute solutions. The preci)jitales form more readily in solutions rendered slightly acid with HjSOj. Excess of the reagent should be avoided. This test is so generally successful in precipitating alkaloids, that a negative reaction is conclusive proof of the absence of ordinary alkaloids, although precipitation is not absolute proof of the presence of an alkaloid. In alcoholic solutions the precipitates are deposited slowly, sometimes not at all, owing to their solu- bility in alcohol. The strength may vary within wide limits. A solution containing 20 grms. of iodine and 50 grms. of potassium iodide per liter is about the right strength. Marine's reagent is a solution of the double iodide of potassium and cadmium. It is employed in solutions acidulated with HjSO^, and gives characteristic precipitates with many of the alkaloids. The double iodide of potassium and bismuth ( DragendorfFs xe- agen^), is made by saturating a hot concentrated solution of potassium iodide with bismuth iodide, and then adding an equal volume of a cold, saturated solution of potassium iodide. It cannot be diluted, but is applicable to solu- tions of alkaloids strongly acidulated with HjSO^. Platinic chloride and auric chloride are frequently employed to precip- itate alkaloids and to distinguish them from other bitter principles. Platinic precipitates have a yellow or yellowish-red color. The gold precipitates of a number of the alkaloids blacken, by reduction, on standing, 788. Color Reactions.— Many of the alkaloids give charac- teristic colors, when in the pure state, by treatment with certain reagents. These color reactions are subject to variations by im- purities, concentration, temperature, and by time. Color reac- tions are, therefore, confirmatory rather than conclusive, and should always be confirmed by control tests upon a portion known to be the alkaloid in question. The reagents that are employed to give color tests are: — (i) Concentrated sul- phuric acid; (2) Frohde's reagent, concentrated sulphuric acid, containing molybdic acid (i mgm. molybdic acid to i c.c. H2SO4) ; (3") Nitric acid, sp. gr. r.40 to 1.42 ; (4) Sulphuric acid, followed by a minute addition of HNOj or KNO,; (S) Sulphuric acid, and cane sugar. The dry substance to be tested, is mixed with six pat th of cane sugar, and a few trgms. of the mixture are placed upon a drop or two of pure H2SO4 on a white plate. The colors given by a nuinber of the most important alkaloids with some of these reagents are given in a table on page 453. ^ S O ^ w .H <: : H O 3 < H 1 & '5. ■| p* T3 o li is Si? "5. a i 5 The addition of a few drops of chlorine water to a solution of berberine in not too small a quantity of hydrochloric acid, produces a red color.- Boiled with perchloric acid a madeira color is developed. A solution in dilute sulphuric acid (i.8) is turned fine red by bichromate of potassium. ■H-3 !! 11 sg-s jC o o SJ'c Z o Mg o.t;.- "? S EA ^ cd .Ig.& IP 4) > Qt en i ■S o c "5 i 4 o •a If the blue color produced by adding saltpetre to the solution in H3SC)4 is allowed to fade away, the residue is colored red by potash. s "3 a* 3 q 1* ■ li S2 ■^ p. 0-2 0-2 zg: i s o O -J 31 (3= Q o o o O o o o o o Si o o o o ° V 3 s o i = ^ * u o It ■s oi o i o i o- ■g 1 £ 4 it- o o o o o o O O ii •^1 51 o ii o O- o o_ o 0-? li o OS, o o o o o o 3 < 1 i t < a S •e 1^ •3 g 3i i 1 u "a .1 a o •g c 5 a ■B ■E o i i IS ■s 3 1 is 'S '5 453 c in a o ►J : < < b O 1/1 z ■ o . t— I , < w o o u 2 O H u Pi g h O il 15 •It "1 |l o c. u o 1 E 3 ■c S •s V -a 1 ■a II a s 1 i 1 i ll 11 1^ s" 'in li ss ISO' •§■? — u si IS- PS II u > fl U 9 .2■ V o Isi oi «1 o P4 o OS o 4 < o o > J5 . ill o o it Is go' o O o III o o It o a s < < 0) '5 o u J i § o 4) B u B 1 o 1 .E o li E ■c > 1 u C 'a bo 1 V s •fr •; B ■E s 454 .fi Q < < O t/) g u <: ai s o u z, o e u s H O 8-" - og i" = .2 ?.-3 !i It ES-I < o':S Is SIC li II H c 1 g a o. o ;z; •s.l' + -nil o •5 = p Jg: o o o > T3 (5 o ■§,„• o o o ~a . as o o c 6 Si am + o o o3 o o u Pi o o T3 . §•5 5" ■5 " r^ s < < 1 c i c g s ■i u 6 s 1 1 455 456 MEDICAL CHEMISTRY. 789. Separation of Alkaloids. — The vegetable substance, the seed, bark or leaf, is first disintegrated and extracted thor- oughly with slightly acidulated water^ which dissolves out the alkaloid. The volatile alkaloids are recovered from the solution by distillation after the addition of an alkali. Non-volatile alkaloids may be precipitated from an acid solution by an alkali, and the impure base thus obtained may be filtered out and dis- ■ solved in acids, and purified by recrystallization. Or, the pre- cipitated alkaloids may be dissolved in alcohol, in which they are generally soluble, and the alcohol evaporated off. In some cases alcohol is employed for the extraction of alkaloids, as most of the alkaloids and alkaloidal salts are soluble in alcohol. The separation and detection of alkaloids in organic mixtures, especially when present in small quantities, requires an expendi- ture of considerable time and patience. When it is undertaken in toxicological examinations it should only be by an expert who has made himself thoroughly familiar with the minutest details of the work. It should not be undertaken by any one without a sufficient feeling of responsibility. The general method em- ployed in such cases is, in outline, as follows : First. The substance to be examined is properly divided, or disintegrated, and digested at about from 40 to 50° C. (104 to 122° F); with water slightly acidulated with H^SO^. After this digestion the solution is filtered and the filtrate evaporated over a water-bath to a thin syrup. This is then mixed with alcohol and digested for several hours at about 3010 40° C. (86 to 104° F.), cooled, filtered, and again evaporated nearly to dryness. The alkaloids will be found in this residue as sulphates. A small quantity of water is now added, and the solution submitted to a series of immiscible solvents— first to the acidu- lated solution, and then to the same solution made alkaline. The acidulated solution is transferred from the evaporating vessel to a separating funnel, thoroughly, and repeatedly shaken for a few minutes with freshly rectified petroleum ether, which should boil at about 65 to 70° C. (149 lo 158° F.). The treatment is repeated until on evaporating a small portion of the ether it leaves no residue, showing that it ceases to dissolve anything. Petroleum ether removes mostly the coloring matter, etc., but none of the alkaloids. Second. This same process is to be repeated with benzene, the boiling point of which is 81° C. (177.8° F.). This removes digitaline, cantharidine, and santonine, which are crystalline, and elaterine, and colchicine, which are amorphous. Third. A solution which has been treated as above is next shaken with chloroform, which removes cinchonine, digitaline, and pyrotoxine. The chlo- roform is next dissolved out of the solution by again shaking with petroleum ether. Fourth. The solution is now made alkaline with ammonium hydroxide, NHjOH, and shaken with petroleum ether at a temperature of about 40° C. (104° F.) when in the petroleum ether will be found any strychnine, quinine, VOLATILE ALKALOIDS. 457 brucine, and veralrine, -if Ihey are present. In a similar manner, petroleum dissolves coniine and nicotine. Fifth. The solution is next shaken with benzene, C^Hg, when any remain- ing strychnine, biucine, quinine, cinchonine, atropine, byoscyamine, physo- stigmine, aconitine, codeine, aid narceine will be dissolved out. Sixth. Chloroform is next emplo)ed in a similar manner, which removes traces of morphine if this alkaloid be present. Seventh. Amyl alcohol is then employed in a similar manner, which dissolves morphine, sclanine, and the glucoside salicin, if present. Eighth. Evaporate the watery liquid with powdered glass and treat the residue with chloroform, when curarine, if present, will be extracted. After all these immiscible solvents have been separated, it then becomes necessary to isolate the residue by distillation of the solvent and, by proper tests, deter- mine the alkaloid present. The most important alkaloids with their behavior with immis- cible solvents are given in tabular form on pages 458 and 459, with their formulae and solubilities. Of the volatile alkaloids two only are of importance. VOLATILE ALKALOIDS. 790. Coniine, CgHisN, an alkaloid obtained from Coniunt maculatum, is a colorless, oily liquid having ah acrid taste and disagreeable odor. It can be distilled when protected from the air. It boils at 212° C. (113° F.). It is sparingly soluble in water, but is more soluble in cold than in hot water, is soluble in all proportions in alcohol. It is soluble in six volumes of ether and is soluble in most fixed and volatile oils. On expo- sure to air it becomes thick and resinous. It gives off vapors at the ordinary temperature of the air which form white fumes with HCI, similar to ammonia. It has been obtained syntheti- cally from butyric aldehyde and alcoholic solution of ammonia. When heated with H2SO4 it gives a red color changing to green and an odor of butyric acid. With nitrobenzene it givesa blue color changing to red and yellow. 791. Nicotine, QoHhNj, occurs in tobacco. It is a color- less, oily liquid which turns brown on exposure to light and air. It has a bitter, caustic taste, and disagreeable penetrating odor. It distils at 250° C. (392° F.), and burns with a luminous flame. It is soluble in water, alcohol, ether, and the oils. It may be re- moved from its aqueous solution by shaking with ether. Its salts are deliquescent and crystallize with difficulty. It gives a violet c'olpr with HCI, and an orange with HNO3. It is actively poisonous, producing death, when given in sufficient doses, some- times with great rapidity. 39 458 MEDICAL CHEMISTRY. Q O H Aconitum napelhis. Atropa belladonna. j Berberis vulgaris. 1 Calumba root. Nux vomica. Coffee and tea. Cinchona bark. Cinchona bark. d S a o *>, ° c tl W O Colchicum autumnale. j Water hemlock. 1 Conium maculatum. Delphinium staphisagria. s s Ed .2 c ■s Hyoscyamus niger. Opium. Opium. Opium. Tobacco (tabacum). Opium. it i2 ^ .„• ^ 2 °' a a a ^ ::^ ^ m * ^ ^ c .£ "^ .S .5 .5 • '. ^ in in tn CO 1 tn t/i §> <" " "? tn" 3 tn £ tn tn tn - u X - a ^. a a a " ^1 § §. 1 ^ ■-■-"" = .s .= en t/i CO g tn CO 3 c 1 ^ in tn si . 3- . 2 . tn '"MM I '■" -^ tn N cq ui ft ! >? en tri ! -S .5 !2 a ;^"- CO . i i " 1 - .f " .1 c/i c/i II "^ m "^ « ■J 0" s" ■b 1 35 ^ 5 S S S S 3 a_^ ; 53^ a^ J E_ u *J. u J J < :, • : • "" -s III iiii 1 f 11 1 1 1 ■■: < « M u u u. 4? u" *« 'C i •i « 3 u u P i 1 .5 s ■2. aj" • ... 1 1 § § s R- NATURAL ALKALOIDS. 459 u as ^ ^ lA « 1 ft J3 c CO id -a 1 1 2 o u c c u cs e c o ■g C o 1 8 g 6 3 C3 s H "« J3 '5. c B 'o. o 2 'S. O O *-> U O U D O m z o O > o . ~^ 2 £ i o. a . p. c/i t/i o Q y) tfi r- in tn N -r 3 M c .5 en c in en C o M in" ■XI "s" 2 ~w "3 i£ K a Q« a. a td "o o "o O .1 'o c H c/i c 1— 1 0\ c u> S m c ii oi cri en ^ en td i i en" -8 -5 en tfi ui en u5 e/i - § en .5 ■= tn P3 «• «5 < - M e: tA c« i cc s" \ ] in' ,1 en U en u5 c en (= in = en en u Z 1 - j2 1 «; c T3 ^ -S O c s. .9* is 4> > •> .3 -? ^ :r # cQ o i; u & m tn f^ en c ■ _: a a M y> s 'i o en c c li- c iz; en en o :n en en en W iz; a R en en en en D '"' _) O p. o en en en en o c en en i c en tn o" o o O o" 6* 09 B> * X a: a X X X o u u U u ^ c a. 5 "So 1 O 'S (4 'c o a a ft Ck i^ en i)5 E z o o " 5 bA < >J X 460 MEDICAL CHEMISTRY. 792. Sparteine, Ci^H^bN, is an alkaloid extracted from the common broom, scoparius. It is a liquid, heavier than water, boiling at 288° C. (550° F.). It is sparingly soluble in water, giving an alkaline, bitter solu- tion. It smells like anilin, and like it, becomes brown on exposure to the air. The sulphate is used in medicine as a heart stimulant. NON-VOLATILE ALKALOIDS. 793. Properties of the Principal Non-volatile Alka- loids. — Aconitine. — Glacial mass, or white powder, crystallizes with difficulty, in rhombic plates. It possesses a sharp, pungent taste, and in general, the physiological properties of the plant, The commercial alkaloid is probably a mixture of several alka- loids, of which aconite root contains at least nine. The alkaloid is very poisonous, and care should be exercised in tasting it. The most characteristic test is the numbness of the tongue and lips which it produces in from one to fifteen minutes after tasting it. This numbness suffices to detect as small a quantity as .01 of a milligramme of the alkaloid. It neutralizes acids, forming crystalline salts. It is precipitated from its aqueous solutions by- alkalies, phosphomolybdic acid, Mayer's reagent and by iodine in KI. It is not pptd. by PtClj, HgCI, or picric acid. 794. Atropine— Daturine — Atropina(U.S.P.) — occurs in belladonna and stramonium. It crystallizes in prisms, or stel- lated tufts, white and fusible. It has a bitter taste, and dilates the pirpil, either when free or as salts. It is odorless. It is distinctly alkaline, and neutializes acids forming crystalline salts. Atro- pinae sulphas, is official, and appears as a white crystalline powder soluble in water. It is an active poison producing dry- ness of the throat, flushing of the face, dilatation of the pupils, loss of speech and of muscular power, dizziness, delirium and coma. Fatal cases of poisoning are not frequent. The treat- ment should consist in removing the unabsorbed drug with the stomach tube, after the administration of some, liquid containing tannin, as tea. A solution of atropine dropped into the eye of a cat dilates the pupil. This is used as a test for the alkaloid. 795. Brucine, Q^^i^^Oi-i^f), accornpanies strychnine in the seeds and bark of different varieties of strychnose, or nux vomica. . It forms oblique prisms or plates, sparingly soluble in water, readily soluble in alcohol, chloroform and amyl alcohol, which readily lose their water when dried in the air. It is in- tensely bitter and has a strong basic reaction, forming crystalline NON-VOLATILE ALKALOIDS. 461 salts. Its action in the economy is similar to that of strychnine, but less active. With strong nitric acid it gives a red, fading to yellow color ; SnClj changes the above red color to violet. Chlorine water colors it a bright red, which is changed to yellow brown by NH,OH. 796. Caffeine — Theine — Guaranine — Caffeina (U.S.P.), CsHioNjO-i -\- HjO. White silky needles ; fuses and sublimes ; has a faint bitter taste ; poisonous in large doses ; 0.4 to 0.5 gr. produces death in cats and rabbits. It exists in coffee, tea and some other plants. Hot, fuming HNO3 turns it yellow, which, after evaporation, and treatment with NH4PH, becomes purple. 797. Cinchona Alkaloids. — Cinchona bark contains a con- siderable number of alkaloids, several of which are employed in medicine. No less than 33 of these alkaloids have been isolated. They exist chiefly, though not wholly, in the bark and are re- markable for their valuable antiper-iodic and febrifuge properties. They all have well defined basic characters, and their salts are usually crystallizable. Their basic character is such that they may be estimated by titration with standard acid. They are but slightly soluble in water, but dissolve more readily in alcohol, and very easily in ether and chloroform. The latter liquids will re- move them from ammoniacal solutions by agitation, but will not from a solution acidulated with H^SOi or HCl. A solution of these alkaloids in H2SO4 exhibits a characteristic strong blue fluorescence. They are precipitated by the fixed alkalies, alka- line carbonates or ammonia. The most important cinchona alka- loids are : Quinine, Quinidine, Cinchonine and Cinchonidine. 798. Quinine — Quinia — Quinina (U. S. P.) — CjoH^NjOj.- 3H2O, exists in the bark of the various species of the cinchona, growing in the mountains of the northern part of South America. Different samples of the cinchona bark vary in the richness of alkaloids. They vary from 33 per cent, to as low as 5 per cent. It occurs as a white, flaky, amorphous, or crystalline powder, permanent in the air, having a very bitter taste. It is soluble in 1670 parts of water and in six parts of alcohol. It is also solu- ble in chloroform, ether, carbon disulphide, benzene, ammonia water and dilute acids. When treated at 100° C. (212° F.) it loses a part of its water of crystallization, but the remainder is expelled at 125° C. (257° F.). It has an alkaline reaction upon litmus paper, brazil wood, or methyl-orange. A sulphate,' bisulphate, hydrobromate, hydrochlorate, and valerianate are official. The tannate, salicylate, phenate, and numerous other salts are employed in medicine. 462 MEDICAL CHEMISTRY. Quinine Sulphate— Quininae Sulphas (U. S. P.) — (C^- H24N202)2H2S04.7H20, is- manufactured on a large scale for use in medicine. It is found in while, silk-like, needle-shaped crys- tals, somewhat flexible, making a very light and easily compres- sible mass, which efflDresces in dry air, absorbs water in moist air and becomes colored on exposure to light. It has a persistent, very bitter taste, and is not very soluble in water but more readily in alcohol. It is soluble in 740 parts of water, 65 parts of alco- hol, in 40 parts of glycerin, and is freely soluble in dilute acids. When exposed to air at a temperature of 100° C. (212° F.) for some hours, it loses all of its water of crystallization. The solution, especially in excess of.HjSO^, exhibits a vivid blue fluorescence. The alkaloid is precipitated on the addition of ammonia water, but the precipitate is soluble in excess of ammo- nia. On treating 10 c. c. of an aqueous solution of the salt with two drops of bromine water, and then with an excess of ammonia water, the liquid assumes an emerald green color. Quinine Bisulphide — Acid Quinine Sulphate — Qui- nine, Bisulphas (U. S. P.) — CjoHj^NjOjHjSOi. 7H2O, occurs as colorless, transparent, or whitish crystals or small needles, odorless, and having a very bitter taste. They are freely, solu- ble in water, exhibiting beautiful blue fluorescence. It loses all of its water of crystallization at 100° C. (312° F.). It gives the same reaction with bromine water and ammonia as the sulphate. Solution of iodine precipitates from the acetic acid solution of the basic sulphate, a tourmaline-like, crystalline body with a green reflection. The solutions of quinine and its salts are laevorotatory. When dissolved in chlorine water, ammonium hydrate produces a deep emerald -green solution. If KjEeCys be first added, NH4OH gives a deep red color. . Quinine Hydrobromas, QoHjiNjOjHBr, Quininae Hy- drochloras, QoHj^NjOjHCl, Quininae Valerianas, CjoHj,- NjOaCsHioOzHjO, occur as white, lustreless, silky needles, odorless and having a very bitter taste, and are official. 799. Quinidine and Quinicine are isomeric with quinine and are found with it. Quinidine is distinguished from quinine by its strong dextrorotatory power. Quinicine is produced by the action of heat upon quinine, and does not exist in the bark. Quinidine occurs in large prisms, soluble with difficulty in water, but soluble in alcohol. Gives the same reaction as quinine with chlorine and ammonia. It has a bitter taste and tonic properties NON- VOLATILE ^ALKALOIDS. 463 similar to quinine, and its salts resemble those of quinine. It is dextrorotatory. The sulphate is official. 800. Cinchona — Cinchonine — Cinchonina — CigHjjN^O, occurs in cinchona bark, together with quinine and the other alkaloids. It occurs in four-sided ' needles, fusing at 150° C. (302° F.). It is soluble in 3810 parts of water and 140 parts of alcohol. Its solutions are dextrorotatory ; chlorine and ammo- nia give yellow precipitate ; separated from quinine by insolu- bility in ether ; very bitter and has less tonic properties than quinine. The sulphate is official. 801. Cocaine, CnH^iO,, is an alkaloid which occurs in the leaves of Etythroxylon coca. It occurs in monoclinic, glistening prisms. Heated with strong HCl, it decomposes. The hydro- chlorate has powerful anaesthetic properties. Coca leaves are used in Peru as a stimulant. Its taste is at first bitter, producing paralysis of the sense of taste and a consequent numbness of the tongue. When heated with strong HCl, it decomposes into benzoic acid, methyl alcohol and ecgonine, CgHisNOs, a new base. Owing to its stimulant and exhilarant properties, cocaine is sometimes employed as a stimulant, and occasionally cases of the cocaine habit are met with, which is often more demoralizing than the morphine habit. 802. Colchicine, C2iH22(CH30)N05, occurs in Colchicum au- tumnale and in other plants of the same family. It is a yellow- white, gummy, amorphous substance, (usually amorphous), with a melting point of about 147° C. (296° F.). It is readily solu- ble in water, alcohol and chloroform. It is employed, like the plant, in the treatment of rheumatism and gout, in doses from y^th to ^Ijfth gr. By the process of hydrolysis, this alkaloid yields a second one called Colchiceine, C2,H220HN05. — This substance is readily solu- ble in boiling water, alcohol and chloroform and but slightly soluble in cold water. It is occasionally employed in medicine. 803. Hyoscyamine, CijHjsNOs, is an alkaloid obtained from hyoscyamus. It occurs as yellow-white, amorphous, resinous- like masses, or as prismatic crystals, having, particularly when damp, a tobacco-like odor, and an acrid, nauseous, bitter taste. It is deliquescent on exposure to air. It is very soluble in water and alcohol, and almost insoluble in ether. It dilates the pupils, like atropine, and possesses sedative properties. Hyoscyaminae Sulphas, (Ci,H23N03)2H2S04, and Hyos- cyaminse Hydrobromas, C^HssNOaHBr, are official. 464 MEDICAL CHEMISTRY. 804. Hyoscine, C„HjiN04, is another alkaloid obtained from hyoscyamus. Hyoscine hydrobromat is official. It occurs in colorless, transparent, rhombic crystals, soluble in water and alcohol. Its solution has a bitter, slightly pungent taste. It is employed as a sedative and hypnotic, and is especially used in mania and neuralgia. It is given in doses of from -^-^ to ^^5 of a grain. 805. Opium and its Alkaloids. — Opium is a concrete, milky exudation of the unripe capsules of the Papaver somnif- erum, or Poppy. It is, chemically, a mixture of a large num- ber of substances, containing gum, albumin, wax, volatile and coloring matters, meconic acid, meconin, and no less than 16 or 18 alkaloids, the most important of which are morphine and codeine. The value of opium in commerce is generally determined by an assay for the quantity of morphine present in it. Ordinary opium should not contain less than 9 per cent, of morphine, and when dried at 85° C. (185° F.) it should contain from 12 to 16 per cent, of this alkaloid, when estimated according to the method of the U. S. P. Opium occurs in the market in irregular or globular masses, with the remnant of poppy leaves adhering to the surface. It is usually plastic in consistency, of a dark brown color, and a somewhat shining appearance. It has a nauseous, peculiar, bit- ter taste. When the gum is dried, powdered, and exhausted with ten times its own weight of strong ether, the ethereal solu- tion separated, and sugar of milk is added, to restore the original weight, it forms the denarcotized opium of the U. S. P. The principal alkaloid of opium is morphine. . Morphine — Morphinae(U.S.P.) — CuHigNOs. It occurs in short, transparent, trimetric prisms, odorless, very bitter, and fusing at 120° G. (248° F.). Morphine is soluble in hot water, alcohol, and amyl alcohol, but nearly insoluble in cold water and only slightly soluble in cold alcohol and amyl alcohol. It gives a blue color with neutral solutions of. FczCle ; it decom- poses iodic acid, giving, free iodine. • Its solutions are laevorotat' tory. It is especially noted for its anodyne properties. Morphine dissolves readily in dilute acids, forming very solu- ble and crystallizable salts, the most important of which are the official sulphate, hydrochlorate and acetate. When heated with large excess of HCl, it gives apomorphine, CnH-nNOj, which is precipitated as a white powder by sodium carbonate, and turns green on exposure to the air. It is said to be formed spontane- NON-VOLATILE ALKALOIDS. 465 ously in old morphine solutions. The hydrochlorate is a speedy, non-irritant emetic. 806. Physostigmine— Eserine— Physostigmina, CisH^i- N3O,, is an alkaloid obtained from the Calabar bean, Physostigma venenosum. It is a crystalline or amorphous brown-yellow pow- der. Its solutions vary in color from red to blue, and are strongly alkaline in reaction. It is a violent poison and strongly contracts the pupils. The salicylate, occurring in crystalline prisms, and the sulphate a yellow-white crystalline powder, are official. 807. Picrotoxine, Ci,HisO.HjO, colorless, lustrous, bitter needles, obtained from the fruit of Anamirta cocculus. It reduces alkaline copper solutions. It has an intensely bitter taste. Soluble in alcohol and in water. It is employed in medicine. 808. Piperine, CnH^NO, is the alkaloid of pepper. It crystal- lizes in colorless, tasteless, inodorous prisms, melting at ioo° C. (212° F.). The alcoholic solution has a sharp, peppery taste and neutral reaction. It is soluble in alcohol, but almost insoluble in water. 809. Pilocarpine, CiiHisNjO-rt is the principal alkaloid of Jaborandi. It is uncrystallizable, but its salts crystallize from alcohol. With HjSOi it forms a colorless solution. The nitrate and hydrochlorate are much used in medicine. Given internally they produce rapid and profuse diaphoresis and salivation, quickened pulse, and lowered temperature. With large doses, the heart stops in diastole. The hydrochlorate — Pilocarpinae hydrochloras (U. S. P.), is official. 810. Strychnine, CjiHjjN^Oj, exists in the seeds and bark of Strychnos nux vomica, and in the seeds of Strychnos ignatice, " St. Ignatius' bean," and other plants of the same family. It crystallizes in white, fusible, four-sided trimetric prisms. Its bitter taste can be detected in a solution containing one part in one million parts of water. It forms soluble crystalline salts. Is a violent poison, producing tetanic convulsions. The physi- ological antidotes are morphine, atropine, and chloral hydrate. A delicate test is to dissolve in sulphuric acid and add a frag- ment of potassium dichromate, when a deep purple-red color is produced. The British Pharmacopoeia does not recognize any of the salts of strychnine. In Germany, the nitrate is official, and in the U. S. P., the sulphate, which is used largely in medicine, as is also the phosphate and nitrate. 811. Theobromine, CiHgNiOj, occurs in the seed or bean of 40 466 MEDICAL CHEMISTRY. Theobroma cacao. It closely resembles caffeine in its physiolog- ical action. It is eliminated by the kidneys, and can be detected in the urine. It forms small, white, trimetric crystals, sparingly soluble in water, alcohol, and ether. It has a slightly bitter taste. The salicylate of theobromine and sodium is used under the name of duretin. Salts are unstable and decompose in contact wiih water. 812. Veratrine, CsoH^sNaOs, occurs in Asagrcsa officiralis. White prisms or powder, melting at 115° C. (239°r.)and solidi- fying, on cooling, to a resinous mass. Its dust causes violent sneezing; it is a violent poison. Concentrated H^SOi forms a yellow solution, which gradually becomes red. It forms crys- talline salts. The oleate and an ointment of veratrine are official. PTOMAINES. 813. Putrefactive, or Cadaveric Alkaloids. — These alka- loids are produced during the putrid decomposition of animal and vegetable matter, and probably in certain pathological con- ditions in the human body during life. Some of these bases are very poisonous, producing symptoms resembling those caused by strychnine, atropine, coniine, etc. Selmi obtained poisonous bases containing arsenic, from the body of a subject who had died of arsenical poisoning, and was ex- humed fourteen days after death. It is probable that the symp- toms of poisoning by preserved foods such as preserved fish, meat, etc., that are occasionally s^een, are due to the presence of some one of these alkaloids. Tainted meat, fish, etc., should not be eaten. The author has known of a number of cases of poisoning from this cause. Some of these alkaloids decompose with great ease, giving a cadaveric odor, while others remain permanent. Although they are most likely to be found in putrefying animal matters, they have been produced by the putrefaction of maize, leguminous substances, flour, etc. Many of the ptomaines are volatile and amorphous, but form crystalline salts with the acids. They answer to nearly all the ordinary reactions of the vegetable alka- loids. They seem to possess less stability, and generally have a greater tendency to undergo oxidation than the vegetable bases, and hence frequently act as reducing agents. The number of these alkaloids that have been isolated is con- siderable. A large number of them belong to the amin group PTOMAINES. 467 of bodies, while certain others contain oxygen, and others have not been sufficiently studied to determine their constitution. Some of these bases so closely resemble the vegetable alkaloids, that they have been mistaken for the latter by chemists. The alkaloids likely to be confounded with ptomaines are coniine, nicotine, strychnine, morphine, atropine, digitaline, veratrine, delphinine, and colchicine. Not only do the ptomaines have many reactions that have been heretofore regarded as characteristic of the above-named alkaloids, but their presence in some cases pre- vents the detection of certain alkaloids by the usual reagents. These facts have a very important bearing upon the toxicological search for the alkaloids. Indeed, serious mistakes have been made by chemists who have had charge of such analyses, owing to imperfect knowledge of these putrefactive alkaloids. The separation of the ptomaines from the vegetable alkaloids, is attended with great difficulty. Tamba states that the oxalates of the vegetable alkaloids are precipitated from solutions of mixtures in ether, while the oxalates of the ptomaines are solu- ble. That is, if to an ethereal solution of the alkaloids, an equal volume of a saturated solution of oxalic acid in ether be added, the oxalates of the vegetable alkaloids separate out on standing, while the ptomaines remain in solution. Cadaverin is said to precipitate along with the vegetable alkaloids. "■ 814. Physiological Action of Ptomaines. — The cadav- eric alkaloids are not all toxic. Of those which are, there is great variation in degree, as well as in the symptoms produced. The free ptomaines are more energetic than their salts. The principal symptoms observed in dogs are the following : ist, dilatation of the pupil, followed by contraction, sometimes irregular contrac- tion of the pupils ; 2d, paralysis of the vasomotor nerves, causing an increased cutaneous heat and injection of the helices of the ears ; 3d, diminished or slowing of the respiration ; 4th, somno- lence, followed by convulsions and death ; 5 th, loss of muscular contractility to electric stimulus. The symptoms in man, although varied by the character of the poison and the condition of the individual at the time, are gen- erally those of a powerful gastro-intestinal irritant. There is usually a period of incubation of from two to six hours. With a given article of food containing ptomaines (undergoing putrefac- tion) there is frequently a remarkable agreement in this period of incubation in diiferent persons, the symptoms in all beginning within a few minutes. There is usually sudden and severe retch- ing, with abdominal pain, prostration, disturbed circulation, and 468 MEDICAL CHEMISTRY. often delirium. There is sometimes dilatation of the pupil and rednfess of the skin, or a fine scarlatinal-like eruption. Thirst is usually intense. Diarrhoea is frequent, but not always found ; the discharges are very offensive. Muscular twitchings and even convulsions may be met with. There is a tendency to collapse, which must be guarded against. The temperature is in some cases elevated, and at others depressed below normal. The above description applies to the symptoms of ptomaine poisoning as usually met with in cases of poisoning by putrid or decomposing food, and not to the individual ptomaines. While the poisonous properties of some ptomaines are well marked, in others they are more or less wanting. The poisonous ptomaines are sometimes called toxins, in order to distinguish them from the non-poisonous ones. The term toxin, however, is more fre- quently applied to poisons produced by bacterial action, without definite knowledge as to whether it be a ptomaine or an albu- minous substance with poisonous properties. Among the non- poisonous ptooiaines, are a number of the amin bases which may be formed by other processes than putrefaction. Among these may be mentioned methylamin, dimethylamin, trimethylamin ethylamin, diethylamin, triethylamin, propylamin, neurodiil, most of which have been mentioned among the amins. Among the amins may be mentioned mydin, CsHuNO, pyrocyanin Ch- HuNOa, and betaine, C5H13NO3. 815. The most important part of the poisonous ptomaines are the following : — Cadaverin, CjHuNa, occurs very frequently in decomposing animal tissue. It is not very poisonous, but is capable of pro- ducing intense inflammation and suppuration, even in the absence of bacteria. It appekrs late in the putrefactive process, but readily in cultivations of the cholera bacillus, and the Finckler- Prior vibrio. It belongs to the diarains and is chemically penta- methylen-diamin. It is a syrupy liquid, possessing an unpleas- ant odor resembling that of coniine. Cholin, CgHisNOj, is similar in properties to neurin, and has been already mentioned- among the organic bases. Muscarin, C5H13NO2, was first discovered in poisonous mush- rooms, Agaricus muscarius. It has also been obtained by the oxidizing action of HNO3 on cholin. It is closely related, therefore, to this base. It has been obtained also from putrid fish. It is a very active poison, acting upon the muscular tissue itself, especially of the heart. It is antagonistic to atropine in its action upon the heart. Atropine may, therefore, be regarded as its physiological antidote. PTOMAINES. 469 Neurin, CjHisNO, is asyrupy base of strong alkaline reaction, and has been obtained synthetically by boiling protagon from brain substance with baryta, and by other synthetic processes. It is a constant product of cadaveric putrefaction, and is a more powerful toxic agent than cholin, with which it is usually asso- ciated. Atropine is its physiological antagonist, and its poisonous symptoms may frequently be dispelled by a hypodermic injection of a small dose of this alkaloid. Cholin, Muscarin, and Neurin usually occur together. They are all active poisons; cholin and neurin acting like curara; mus- carin acting on the muscular tissue itself. They are all antagon- ized by atropine, so far as relates to their action on the heart. They are usually present in the putrefaction of proteids, and are often concerned in producing the symptoms seen in cases of poisoning by putrid meats. Gadinin, CvHjeNOj, has been obtained from putrefying cod- fish. Mytilotoxin, CgHisNOj, is the active agent in poisonous mussels. Typhotoxin, QH^NOz, is an alkaloid which has been ob- tained from pure cultures of the bacillus of typhoid fever, and is supposed to be the chemical poison concerned in producing the symptoms in this disease. Typhotoxin, when injected into the circulation of animals, produces a lethargic or paralytic condition, in which the animal falls down helpless. Frequently diarrhceal evacuations take place, and death follows in from one to two days. Tetanin, CiaHsoNjOi, is supposed to be the chemical poison in cases of tetanus. It produces in animals the characteristic symptoms of tetanus, such as tonic and clonic convulsions. Tyrotoxicon is a poison which has been separated from poisonous cheese, ice-cream, and milk. Its true chemical com- position has not yet been established. It is supposed to be the active agent in producing the symptoms usually seen in cases of cheese poisoning. Putrescin,*C4Hi2N2, tetramethyldiamin, is usually found accompanying cadaverin, but makes its appearance much later. It is found together with cadaverin in faeces and urine. It is a poison, but not very virulent. The symptoms produced by it are very similar to those of cholera, but the muscular cramps and other symptoms produced in cholera are probably caused by other poisonous substances. 47° MEDICAL CHEMISTRY. TOXINES. 8i6. Poisonous Proteids and Allied Poisons.— Protein substances readily undergo decomposition under the influence of the growth of various micro-organisms. Some of the.se decom- position products, when introduced into the circulation, are poisonous. -The poisonous proteids are not easily distinguisliable by chemical or physical properties, from non-poisonous or food proteids. The most important of the vt-getable proteid poisons, are those contained in the seeds of Jequirity, that associated with papain, and that from lupinus luteus. The most important of the animal poisons are, snake poison, the proteids in the serum of the conger eel, that found in certain spiders, albumoses, and peptones. In the case of snake poison, no bacteria seem to be present, and the proteids obtained in the pure condition, are as poisonous as the original venom. The venom of the cobra and viper, according to the most recent analysis, are found to contain globulin, albumin, and syntonin in the former, and globulin, albumin, and albumoses in the latter, all of which are poisonous. The chief symptom produced is asphyxia. The disease-producing bacteria form, as a result of their growth, certain substances which are more or less. poisonous. Pure cultures of the anthrax bacillus produce a substance which, if inoculated into animals, renders them im- mune from anthrax. This principle is believed to explain the cause of immunity in animals who have suffered from certain specific diseases. The immunity of animals who have suffered from a contagious disease, is supposed to be due to the production of these products of the growth of the specific micro-organism of that disease, and immunity niay be produced by injecting these products. Most specific organisms produce a toxine, or poison, and a vaccine, or protective principle. It does not, however, appear that in all cases two substances are necessarily formed. The bacillus of diphtheria has been shown to produce a proteid which, when injected into animals, produces diphtheritic symp- toms. These proteids obtained from bacterial growth have been named toxalburains. They appear, however, to be albumoses rather than albumins. Other poisonous proteids have been obtained from cultures of the bacilli of tetanus, cholera, typhoid fever, and cholera infantum. The proteids found in the latter case are usually highly poisonous when injected under the skin of dogs or other lower animals, producing vomiting, purging, LEUCOMAINES. 47 1 collapse, and death. Koch's tuberculin is the impure tox- albumin, or alburaose, resulting from the growth of the tubercu- lar bacillus in pure cultures. Tuberculocidin is the purified albumose which is used in the treatment of tuberculosis. The amount employed is said to be about }i grain per day. LEUCOMAINES. 817. This term is applied to those alkaloidal or basic sub- stances elaborated in the body during life. They are either the result of fermentative changes within the body, or of the natural physiological processes in the retrograde changes in the nitro- genous tissues. The most of these alkaloids are deleterious to the subject. They act especially upon the nerve centres, pro- ducing sleepiness, lassitude, or occasionally vomiting and purga- tion. Some of them produce a febrile condition, while others produce a lowered temperature. Some of them are to be found in the excreta, viz. : in the urine, faeces, perspiration, breath, etc. Some are to be found principally in the muscles, saliva, brain, liver, spleen, and other glandular bodies. The quantity and character of the leucomaines vary with pathological condi- tions. The urinary leucomaines have received special study. Though scarcely to be found in certain normal urines, they are greatly increased in certain diseases, so that this fluid miy at times become very poisonous when introduced into the circula- tion. Without giving a detailed description of these bodies, we give the following list of names, formulae, and sources of the principal leucomaines : — 818. The Betain-Uric Group of Leucomaines. — These are all closely related to uric acid, as will be seen by comparison of the formulae. The most of them have already been described in a former chapter. - (Uric acid, CsH^N^O,.) Adenin, C5H5^f5, pancreas, spleen, kidneys, lymphatic glands. Hypoxanthin, CjHjNjO, spleen, muscles, urine, kidney, etc. Guanin, C5H5N5O, guano, liver, pancreas, lungs. Xanthin, CjHjN^O,, urinary calculus, almost all tissues. Heteroxanthin, C^HgN^Oj, urine of man and dog. Paraxantliin, C,HjN402, urine of man. Carnin, CjHgN^Oj, extract of meat. Pseudoxanthin. C^HjNjO, beef muscle. Spermin, CjHsN, spermatic fluid, sputa of bronchitis, spleen. 472 MEDICAL CHEMISTRY. 819. The Creatinin Group of Leucomaines. — Creatinin, CjH,N,0, urine. Creatin, C^HgNjO. urine. Xanthocreatinin, CjHijN^O, muscle. Crusocrealinin, CjHgN^O, muscle. Amphicreatinin, CjHigNjOj, muscle. Some of th€se bodies are said to be poisonous, and it is suspected that uraemia arid many of ihe neiAous symptoms of djspepHa are due to their action. There are probably many more of these substances than have been isolated. It is known that there are certain poisonous substances destroyed in the liver. There are certain poisons thrown out with the breath, the urine in certain diseases, the saliva of man and other animals, and in various other tissues and fiuids. Much remains to be known of these substances. THE GLUCOSIDES. 820. The glucosides are a class of compounds widely distributed throughout the vegetable kingdom. They may be resolved into a sugar and another compound by acids, alkalies, or ferments. They are probably ethers of glucose. A few of them occur in the animal body. Many of them are used in medicine. We can mention here but a few of the more important of these bodies. Amygdalin, C2(|H2,NOii, occurs in bitter almonds, in kernels of cherries, plums, apricots, and in leaves of laurels. Extracted from almonds by boiling alcohol, and precipitated by adding ether, it is obtained as pearly scales. Crystallizes in prisms. When emulsin (the ferment of bitter almonds) is added, it splits up into prussic acid, HCN, benzaldehyde, CeHaCOH, and glucose. Arbutin, CisHisOa. — Extracted from leaves of Uva-Ursi. Soluble in water, has a bitter taste, and is crystalline. Emulsin and dilute acids yield glucose and hydroquinone. Antiarin, CuHzoOjaHjO. — The active principle of the arrow- poison of Java J crystalline, soluble in water and alcohol. Ob- tained from the milky juice of Antiaris toxicaria. Coniferin, CieHjjOs, occurs in the carabian layer of the conifercB family, and crystallizes in stellate groups of prisms. Emulsion yields glucose and coniferyl alcohol. This latter, when treated with sulphuric acid and potassium dichromate, yields artificial vanillin, a body identical with that obtained from the vanilla bean. It is now manufactured on a considerable scale. Convolvulin, CsiHjoOis. — Active principle of jalap; a resin- THE GLUCOSIDES. 473 ous mass, soluble in alcohol and alkalies. Jalapin exists wiih the above in jalap. Digitalin. — A poisonous substance existing in common fox- glove ; forms an amorphous powder having an intensely bitter taste. It is readily soluble in water and absolute alcohol. Four glucoside principles have been described as occurring in digi- talis ; digitalein, digitonin, digitalin, and digitoxin. Digi- talein, whose formula is C5H8O2, occurs as a yellowish amorphous powder, freely soluble in water and alcohol. It is said to com- bine the properties of digitalin and digitoxin. Digitoxin, CjjHaOt, is a white crystalline body of a bitter taste, readily soluble in chloroform, but insoluble in water. When subjected to hydrolysis it does not yield sugar but other products. It is used in medicine. Esculin, CjiHjjOis, and Esculetin, CsHeO,, occur in the bark of the horse-chestnut tree; sparingly soluble in cold, more freely in hot water, are crystalline and have a bitter taste. Fraxin, CjsHseOj, is found in the bark of the ash and horse- chestnut tree, and forms colorless, needle-like crystals, soluble in water, furnishing a bitter, fluorescent solution. Glycyrrhizin, or Liquorice- Sugar, CiiHseO,, is the sweet principle of licorice. It is a yellow, amorphous powder, having a sweet, acrid taste. It is soluble in water and alcohol. Acids split it into glucose and glycyrrheiin. Helleborin, CsjH^Oe, is found together with helleborein, CjjH^jOiB, in the root of green hellebore. It is insoluble in water, and forms glistening needles. A powerful poison. Indican, CjzHejNjOM, occurs in all plants yielding indigo. It is a pale-brown, syrupy liquid, having a bitter taste. When allowed to ferment, or when treated with dilute acids, it forms indigo blue and indiglucin, a form of sugar. Indigo has been prepared synthetically from cinnamic acid, which may be pre- pared from toluene. A substance called indican is found in the urine, but this is not identical with plant indican. Populin, C20H22O8, occurs with salicin, in the bark and leaves of the aspen. It forms small prisms, having a sweet taste. Boiled with barium hydroxide, it yields salicin and benzoic acid. Phlorizin, QiHj^Oio -f 2H2O, occurs in the root bark of the apple, plum, pear and cherry tree, and is soluble in alcohol. It is soluble in hot water, from which it crystallizes in silky needles having a bitter laste. Boikd with dilute acids, it yields glucose and phloretin. 474 MEDICAL CHEMISTRY. Polychroite, CisHmOib, is the coloring matter of saffron, and forms an amorphous, deliquescent, ruby-red mass. Quercitrin or Flavin, CaiHaaOu, occurs in tea, quercitron, sumach, grape-vine, catechu, etc. It is slightly soluble in water, soluble in alcohol, and forms small, yellow crystals, which may be partially sublimed in beautiful yellow needles. It is colored green by FejClg. Salicin has already been described under Salicylic Acid, q.v. Santonin — Santoninum (U.S. P.) — CisHuOs, is a glucoside with acid properties obtained from various species of Artemisia. It crystallizes in colorless, tasteless, odorless, rectangular prisms, which turn yellow on exposure to the light. It is sparingly soluble in hot water, alcohol and ether, and insoluble in cold water. Patients taking santonin excrete the coloring matter by the urine, which assumes a yellow color, which, on treatment with an alkali, changes to cherry red or crimson, this color being discharged by an acid. The coloring matter is also de- posited in various other tissues and when a patient is taking large doses, objects appear green from the staining of the tissue of the eye. Saponin, CsaHjjOis, occurs in quillaia, ox soap-tree bark, and other plants. Soluble in water and alcohol. Its solution behaves like soap solutions. It is poisonous, but it is sometimes added to soda water to produce a permanent froth. Its dust causes sneezing. Solanin, C„Hg,N0i6, occurs in sprouted potatoes. It is a glucoside ; soluble in alcohol, nearly insoluble in water, and forms gum-like salts. Strophanthin, CjoHjtOio, is a glucoside obtained from strophanthus, in the form of white, bitter, crystalline plates ; slightly soluble in water, soluble in alcohol and insoluble in ether, carbon disulphide or benzene. The Tannins form a group of bodies found widely distributed in plants. These bodies are soluble in water, have an acid reac- tion, an astringent bitter taste, and form an insoluble compound with gelatin and albumin. Thety unite with animal skin, form- ing leather. With ferric salts, they form blue-black or green precipitates. They are used in the preparation of inks, in dye- ing and tanning. Gallotannic Acid — Acidum Tannicum (U. S. P.) — CiiHgOsH, occurs in oak birk, nutgalls, sumach and some other plants, in considerable quantities. It may be extracted with a mixture of ether and alcohol. -It is an amorphous, shining PROTEIDS. 475 mass. Ferric salts give with it a bluish-black precipitate (ink), tartar emetic a white one. It precipitates starch, gelatin, albu- min, and most alkaloids. Its watery solutions decompose when exposed to the air for some time, yielding gallic and ellagic acids. Dilute mineral acids, when boiled with it, give gallic acid and glucose. Quinic or Quinotannic Acid, C,H,j06, occurs chiefly in cinchona barks as a salt of quinine, but is also found in the bil- berry and coffee bean. It occurs as oblique, rhombic prisms. It is soluble in water. On dry distillation it yields, among other products, benzoic acid and phenol. Other tannic acids are known, as cafFeetannic, of coffee ; quercitannic, of oak ; catechutannic, of catechu ; kinotannic, of kino, etc., which vary slightly in properties, according to source. PROTEIDS. ALBUMINOUS COMPOUNDS. 821. This important class of bodies form the chief part of the solid constituents of blood, muscle, lymph, glands and other organs of animals, and are also found in plants, principally in the seeds. They are the principal substances taking part in the physiological changes in the organism. They are colloid (not crystalline), do not readily diffuse through anima> membranes, and are very prone to putrefaction. They all contain carbon, hydrogen, nitrogen and oxygen, while most of them contain sulphur in addition, andall contain some ash, mostly in the form of calcium phosphate. Independent of the ash, they have the following composition : — Carbon, 52 to 54 per cent, Hydrogen, 6.7 to 7.3 Nitrogen, 13 to 18 Oxypen, 21 to 26 " Sulphur, 0.4 to 1.6 " This would give approximately the formula Ci36H2,9N3504,S. GENERAL PROPERTIES OF THE PROTEIDS. 822. Solubility. — All proteids are insoluble in alcohol, some are soluble in water, others insoluble. Some of those insoluble in water, are soluble in weak saline solutions. Some are insoluble in concentrated saline solutions, while others are soluble. AH 476 MEDICAL CHEMISTRY. proteids are soluble with the aid of heat, in concentrated mineral acids, caustic alkalies, and acetic acid. They are soluble in the gastric and pancreatic juices, but, in these last cases, they under- go chemical change during solution. Heat Coagulation. — Many of the proteids, which are solu- ble in water or NaCl solutions, are rendered insoluble when these solutions are heated to near the boiling point. This precipita- tion is termed coagulation. The temperature at which the proteids coagulate is fairly constant for the same substance, and, as different proteids coagulate at different temperatures, this method may be employed for the separation of mixtures of dif- ferent proteids. Unless in very concentrated solutions, they are not coagulated by heat in alkaline solutions, but are con- verted into alkali albumin. Acid albumin does not form so readily as alkali albumin, and hence slightly acidulated albumin solutions coagulate readily. Excess of acid, however, dissolves the precipitate, thus forming an acid albumin. The temperature of coagulation of the different proteids varies between 73° and 84° C. (163.4° and 183.2° F.) for albumins, and between 56° and 7s°C. (132.8° and 167° F.) for globulins. All proteids which are coagulated by heating their solutions, come under two classes ; the albumins, which are soluble in water and weak saline solutions, and the globulins, which are insoluble in water and soluble in weak salme solutions. All the proteids are Isevorotatory. If pure and in solution, they may be detected and estimated by their specific rotatory power. The specific rotatory power of serum albumin is — 56 ; egg albumin, — 35 ; serum globulin, — 59-7. - GENERAL REACTIONS OF PROTEIDS. 823. First. Heated with strong HNO3 they, and their solutions, turn yellow, which deepens into an orange color on adding NH^OH, NaOH or KOH. (Xantho-proteic reaction). If proteids be present, except albumoses and pep- tones, a yellow precipitate is always obtained on adding the acid. Second. Millon's reagent is prepared as follows : One part, by weight of mercury and two of strong HNO3 are mixed and gently warmed until the mercury is dissolved. The solution is diluted with twice its bulk of water, and the precipitate allowed to settle. The clear supernatant fluid is Millon's re- agent. If a few drops of this solution be added to a solution of the proteids, a white precipitate occurs which, on heating, becomes a brick red color. If they are present in only traces, no precipitate is obtained, but the solution is colored red. Third. Add excess of glacial acetic acid, and th^n concentrated HjSOj. A violet color with a feeble fluorescence is formed if proteids are present. This reaction is not delicate. (Adamkiewicz's reaction.) PROTEIDS. 477 'HxvHd-ins aHddo^ • ■ • • • • • • • S-2 aadJO^ HXIM. HaixoaaAH nniaos "oS 2 - - > •q' 2 - 5 2 :: > o > : : : 13 a! i ■aazaoi oiunoHaj^ •ssvioj '£ *ao 'sivis -ONQX Mniaog 'a laioy oiaDij 'i HXiM aiDv oixaDV •2 D.- - - - D.* - * -^ - » '6 z : : a- - •0 c HilAV MINMVX MO ^OHO^^v aimosay 3 D.- - * - ■s o.- - "• - - - : : = a* " t =ONH aanj D." - - 5 ■saiiEitiB -pWE Oh : z : ■B ft: •0 2 "HaiNVADoaaa,,; ■SSVXO^ HXIM ai3V 3tLH3V 3 a- - - - 3 a,- - - - - - '2 o. : : z ■2. a. p. 2 HXIM NOiivanivS- ■6 a- - - = a- - - " * - a : : : 2. a- 0. a :z; HO ^OV^lJ dO NOIX -mos auxvanxvg a. 0-, ^ ^ ^ o 2 !=. = = !. 1 -3 = : 5 ')oq uaifAL siqniog a.- 13 ! 2 •(jSS ox i) iZ)Vii ao tfic/j'cficnc/5 •3ui -Iioq uo'-pidj M : : : c/5cn CO u5 'N0ixinnDV03 HO aanxvuadHax uucjud o o a o o ud 'ud'JcJ O O "O o o o - ■{WHVAV HO aio;^) aaxv^ Ni Axniamog tfi(/)tnt/;m (T, , C 5 : : u5 C t/3 c/i ^ a u O U g •< : : . ■ 1 -a ■4 ii tn<(J is s ii i |i 1 a c 1 Serum Albumin, Muscle " Lactalbumin, . Serum Globulin Fibrinogen. . Globin, . . . 478 MEDICAL CHEMISTRY. . Fourth. If albumin is precipitated with alcohol aud washed with ether, it gives a deep violet color when heated with HCl. (Liebermann's reaction.) Fifth. If mixed with excess of strong solution of NaOH, and one or two drops of a dilute solution of CuSO, be added, a violet color is obtained, which deepens in tint on boiling. (Piotrowski's reaction.) In the case of albumoses and peptones, the color is rose-red with KOH, and reddish- violet with NH^OH. This is also termed the biuret reaction. The above tests serve to detect traces of proteids, and depend upon the de- velopment of colors. The following reactions depend upon the precipitation of the proteid from its solution. Sixth. Make the fluid strongly acid with acetic acid and add a few drops of a solution of KjFe(CN)j. The precipitate shows the presence of proteids, except peptones and some forms of albumose. Seventh. Render the fluid strongly acid with acetic acid and add an equal volume of a concentrated solution of Na^SOj and boil. This precipitates all proteids except peptones. This test is useful because it effects a very complete separation of proteids, except peptones, and the reagent employed does not in- terfere with other tests which are likely to be performed upon the solution, after the removal of the proteids by filtration. It is, therefore, useful to separate albumin from solutions before testing for sugar. The following precipitate all proteids : Tarinic acid in the presence of a faint excess of acetic acid ; double iodide of mercury and potassium with slight excess of HCl (Brucke's reagent) ; phosphotungstic acid in the presence of a considerable excess of HCl ; excess of absolute alcohol in neutral or faintly acid solutions. Various neutral salts, more particularly ammonium sulphate and magnesium sulphate, have been employed for the precipitation and separa- tion of the several proteids. CLASSIFICATION OF THE PROTEIDS. 824. The proteids are conveniently classified as follows: Class I. Native Albumins. — Soluble in H^O ; solution co- agulated by heating, especially with dilute acids ; not precipi- tated by alkaline carbonates or NaCl ; e. g., egg albumin (pptd. by ether), serum albumin (not pptd. by ether), cell albumin, m.uscle albumin, lact-albumin. Class 2. Globulins. — Insoluble in water; soluble in dilute NaCl solutions; soluble in very dilute acids or alkalies; with strong acids and alkalies rapidly changed into members of Class 3 ; readily precipitated by saturating their solutions with NaCl, MgSOi, (NHJuSOi, and certain other neutral salts; their solu- tions are precipitated by heat; e. g., i, crystallin, of the crys- talline lens; 2, vitellin from eggs; 3, serum globulin or para- globulin; 4, fibrinogen; 5, myosin; 6, globin. Class 3. Derived Albumins, or Albuminates. — Insoluble in distilled water and in dilute neutral saline solutions; soluble in acids and alkalies; solutions not coagulated on boiling; ALBUMINS. 479 e.g., acid albumin, or syntonin, and alkaline albumin, casei- nogen. Class 4. Fibrins. — Insoluble in water; difficultly soluble in strong acids and alkalies, and undergoing a simultaneous change into members of Class 3 ; soluble by prolonged action of 10 per cent, solution of NaCl, with change into members of Class 2. Class 5. Coagulated Proteids. — These are products of the . action of heat on members of the preceding classes, or of Class 3 when pptd. by neutralization and heat. They are also obtained by the prolonged action of alcohol in excess upon Classes i, 2, and 4. Class 6. Albutnoses (proteoses or pro-peptones) and Pep- tones. — The peptones are very soluble in water ; are not preci- pitated by acids, alkalies, neutral salts, or many other reagents which precipitate other proteids. They are precipitated by prolonged action of strong alcohol, but not coagulated. They are readily diffusible. The albuminoses are readily soluble in water, and are distin- guished from the peptones by being precipitated by saturation with neutral ammonium sulphate. They yield precipitates with many of the reagents which precipitate other proteids. A char- acteristic feature of the albumoses is, that the precipitate with HNO3 and KiFe (Cy)6, in presence of acetic acid, disappears when the solution is warmed and reappears on cooling. Class 7. Lardacein, or Amyloid Substances. — Insoluble in water, dilute acids, and alkalies; converted into albuminates by strong acids and alkalies. ALBUMINS. 825. Serum Albumin exists in blood, chyle, lymph and in small quantity in milk. In certain renal diseases, it appears in the urine. When its solutions are heated to about 73° C. (161.6° F.), it coagulates toa flocculent precipitate, which, when dried, forms a compact mass. Its solutions have a specific rotatory power of — 56° Strong mineral acids first precipitate it, then dissolve the coagulum. It is not precipitated by acetic acid alone, but when acidified with this acid, potassium ferrocyanide and ferricyanide coagulate it. It may be obtained from blood serum by saturating it at 36 C. (96.8. F.) with MgSOi, which precipitates the globulin. The filtrate is saturated with sodium sulphate at about 4o°C. (104° F.), which precipitates the serum albumin, containing small quan- 48o medica'l chemistry. tities of salt. To obtain it pure, this precipitate is suspended in water and submitted to dialysis. Pure serum albumin is a white, or pale yellow, amorphous sub- stance, dissolving readily in water, forming a slightly alkaline, opalescent liquid, slowly coagulating at about 73° C. (163.4° F.). It is not precipitated by ether, and with difficulty by alcohol. The following reagents may be used to detect its presence in solution ; citric or acetic acid with potassium ferrocyanide, potas- sio-mercuric iodide, mercuric chloride, picric acid, concentrated nitric acid, or trichloracetic acid. Egg Albumin is found in the white of eggs, and differs from the above in being almost insoluble in nitric and hydrochloric acids, and is precipitated by alcohol and ether. Its specific rotary power is less than that of serum albumen, being — 35-5. The white of egg is a semifluid substance, situated between tTie shell and the ovum proper, or yolk. It is permeated by a meshwork of fibrillated matter. This network is insoluble in hot water, dilute alcohol and acetic acid. The liquid is alkaline in reaction, and especially rich in proteids, containing about 12.2 per cent, as a mean, varying considerably in different eggs from II to 13 per cent. It has the following composition ; water 82 to 88 percent., solids about 13.3 per cent. "proteids about 12.2 per cent., sugar about .5 per cent., fats, alkaline soaps, lecithin, and cholesterin about .66 per cent. (Lehman.) The proteids of white of egg are : i, globulins, precipitated by dilute acetic acid, or by saturation with MgSOi or NaCl ; 2, al- bumins then remaining. Vegetable Albumin occurs in small quantity in most vege- table juices. It shows the same general properties as the other albumin, but contains less sulphur. THE GLOBULINS. 826. The globulins differ from the albumins in being insolu- ble in water, but soluble in sodium chloride solution (i per cent.). Except vitellin, they are precipitated by saturated solutions of the same salt. They are soluble in very dilute HCl (i part in 1000 being sufficient), with production of acid albumin. Vitellin occurs in yolk of egg. A white granular body, solu- ble in dilute NaCl solutions, and not precipitated by a saturated solutionof the same. It coagulates at about 75''C. It dissolves readily in dilute acid (^ per cent.) and in alkalies. It is pre- cipitated by alcohol. THE GLOBULINS. 48 1 It is readily soluble in i per cent, solution of NajCOj and is inconnpletely precipitated from its solution by dilution, but com- pletely by passing a stream of COj through it. It has not as yet been obtained free from lecithin. It may be prepared from egg yolk, by extraction with successive portions of ether as long as it yields any color to the solvent. The ether is evaporated, the residue is dissolved in the smallest possible amount of 8 to lo percent. NaCl solution. It is precipitated from this solution by excess of water, and purified by the repetition of this process. The operation must be conducted as rapidly as possible, since the prolonged action of water renders the vitellin insoluble in NaCl solution. Thus obtained, it is still a mixture of vitellin with a small amount of lecithin. Crystallin is usually regarded as identical with vitellin. It can be prepared in the pure form from the crystalline lens, in which it occurs to the extent of 24.6 per cent. In dilute saline solution it coagulates at 75° C. Serum Globulin — Paraglobulin — Fibrinoplastin — oc- curs in blood, chyle, lymph, serous fluids. In many of these fluids it exists in large quantity, and these coagulate spontaneously when removed from the living body, forming fibrin — probably by the combination of two modified forms of globulin, called fibrinogen and fibrinoplastin. Globulin is not completely precipitated by a saturated solution of NaCl, but is precipitated by alcohol, or by carbon dioxide allowed to bubble through the liquid. Pure paraglobulin is insoluble in water. Its dilute saline solu- tion coagulates on heating to 75" C. (167° F.). Globulins also occur pathologically in the urine, and may usually be discovered by dropping a few drops of the urine into a large quantity of dis- tilled water, when the globulin is precipitated as a white cloud. Cell Globulin has been described as occurring in lymph cor- puscles, and may be extracted from them by NaCl solutions. Fibrinogen. — This globulin is found in blood plasina, to- gether with paraglobulin and serum albumin. It is also found in chyle, lymph, serous fluids, transudations, and hydrocele fluid. During the clotting of blood it is converted largely, if not entirely, into fibrin. It resembles paraglobulin in its general properties, but is distinguished from it by the fact that in blood plasma, or in I per cent, solution of NaCl, it coagulates at 56° C. (132.8° F.), while paraglobulin coagulates at 75° C. (167° F.). It is also readily precipitated by the addition of 16 per cent, of NaCl to its solution, whereas paraglobulin is not precipitated until at least 20 per cent, is added. 41 402 MEDICAL CHEMISTRY. It may be prepared from blood plasma which has been pre- vented from coagulating by the addition of MgSO^. By the addition of an equal volume of a saturated solution of NaCi, the fibrinogen is precipitated while the paraglobulin remains in solu- tion. The characteristic properties of fibrinogen are that in the presence of minute quantities of certain salts, of which NaCl and CaSOi are examples, the addition of fibrin-ferment causes a rich formation of fibrin. Without such addition, the solution of fibrinogen may remain permanent. Myosin. — When an irritable contractile muscle passes into rigor mortis, the substance of which the muscle fibrillae are com- posed undergoes a change similar to the clotting of the blood, which results in the formation of a clot of myosin. Myosin is the name given to a solid which separates on the coagulation of muscle plasma. Muscle plasma, freed from blood, is a yellowish, opalescent, syrupy fluid, which filters with difficulty, and clots spontaneously at temperatures above o° C. (32° F.). It may be diluted with solutions of varying strengths of several neutral salts, by which its_clotting may be delayed, and the changes it under- goes may be studied. Muscle plasma contains a globulin, myo- sinogen, which is a generator of myosin, which resembles fibrin- ogen, and coagulates at 56° C. (132.8° F.). This is converted into myosin on clotting by the action of a specific ferment, and there remains in the solution, after the formation of the clot, myoglobulin and an albumin resembling serum albumin. Apart from these general reactions, myosin is distinguished by its low heat coagulation temperature, 56° C. (132.8° F.). It is con- verted into an insoluble proteid by the prolonged action of water, and into syntonin by the action of acids. Globulins closely resembling myosin, occur in vegetable protoplasm and in the cells of the liver. Myosin is readily digested by pepsin, more slowly by trypsin. Globin is produced by the spontaneous decomposition of hemoglobin on exposure to the air. It is an insoluble proteid of which little is known. It is scarcely soluble in dilute acids or alkalies, or in solutions of NaCl. DERIVED ALBUMINS, OR ALBUMINATES. 827. There are two forms of these compounds, the acid albumin and alkali-albumin. They are obtained by dissolving albumin in acids or alkalies. Some of the acid-albumins contam sulphur, while the alkali-albumins do not. When freshly pre- DERIVED ALBUMINS, OR ALBUMINATES 483 pared, they are soluble in dilute acids, alkalies, and alkaline carbonates, and their solutions are precipitated by careful neu- tralization, but not by boiling, and with difficulty by alcohol. Globulins are more readily converted into acid-albumins than the native albumins. Coagulated proteids, as fibrin, require acid in a concentrated form. As obtained from the various proteids, the products exhibit certain marked differences, indicating that each proteid yields its own special acid-albumin. Preparation of Acid-albumin. — Blood serum, or dilute white of egg, is digested at 40° to 50° C. (164° to 122° F.) for several hours with i per cent, to 2 per cent. HCl. The solution is filtered, carefully neutralized, and the precipitate col- lected on a filter and washed with distilled water. It may be rapidly prepared by beating the white of egg with glacial acetic acid. A jelly is thus formed which can be dissolved in warm water, and from this solution the acid-albumin is precipitated by neutralizing and washing as before. Syntonin is merely an acid-albumin which results from the action of acids on myosin, or muscle globulin. It has certain properties which distinguish it from the similar products of the action of acids on other proteids. For example : It is soluble in lime water; it is insoluble in acid sodium phosphate, NaHj- PO4 ; while other acid-albumins are soluble. When precipitated from its acid solution by neutralizing, the precipitate is more gelatinous than that of the other acid albumins, and is less readily soluble in alkalies. Alkali- alt)uniin may be obtained by the action of dilute alkalies on native albumin solutions, upon coagulated albumm or other proteids. The jelly produced by the action of KOH solution upon white of egg, is alkali-albumin. If serum, egg albumin, or muscle juice be treated with dilute alkali, the pro- teid undergoes a change, and is converted into alkali-albumin. This solution is no longer coagulated by heat. The proteid is entirely precipitated on neutralization, and the precipitate is in- soluble in water and in neutral NaCl solutions, and is readily soluble in dilute acids or alkalies. It has been a matter of con- siderable discussion, whether acid-albumin and alkali-albumin, when precipitated by neutralization, are identical or different substances. Casein or Caseinogen is a natural alkali-albumin found in milk of mammals, and differs only in some slight particulars from that found in blood, muscle, etc. Casein exists in milk in the soluble form, or in a state of semi- 484 MEDICAL CHEMISTRY. solubility. Under a high magnifying power the casein can usu- ally be seen as very fine granular particles, and therefore a por- tion of it, at least, must be in suspension, instead of in actual solution. There is a slight difference in the composition and properties of casein of cows' and of human milk, which explains a part of the difference in digestibility of the two. The former is more soluble in water and alcohol than in the latter. Casein is somewhat richer in nitrogen than alkali-albumin ; it yields sul- phur to heated potassium hydroxide, which alkali-albumin does not. It is coagulated by rennin, which is not thecase with alkali- albumin. Its solutions do not coagulate on boiling, are precipi- tated by most acids, but not by simple neutralization in presence of an alkaline phosphate. Potassium ferro- and ferri-cyanides and dilute sulphuric acid precipitate casein in presence of free acetic acid. Rennet contains a special curdling ferment, rennin, as also do gastric and pancreatic juices, which can precipitate casein from alkaline solutions at slightly elevated temperatures. This precipitation is due to the specific action of an enzyme, which results in the formation of a substance differing essentially from casein and called tyrein. It has been proposed to call the coagulated product casein, and the substance in solution caseinogen. The relation of these bodies is the same as that between fibrin and fibrinogen. Simultaneously with the forma- tion of the clot, a by-product is formed having the properties of the soluble albumins. The curd differs from casein in the fact that it is less soluble " in acids and alkalies ; casein always leaves a [larger amount of residue on ignition. Calcium phos- phate seems to play an important part in the coagulation of casein. If the casern be freed from calcium phosphate, and dissolved in a dilute alkali, it will not yield a curd. It may be also stated that casein precipitated by acids instead of by rennin cannot be em- ployed for the . manufacture of cheese, as it will not " ripen." Cheese can only be made by the use of rennin. When milk is submitted to dialysis, to separate the inorganic salts, it yields no clot ; but if the salts be added again it yields a clot with rennin. The action of calcium phosphate appears to be, that it assists in the separation of the clot from the solution. The calcium salt is not alone essential for this, as similar salts of Mg, Ba, or Sr will give similar, though less efficient, results. Solutions of the alkali-albumin cannot be made to clot by the action of pure rennin. The casein of cows' milk differs from that of human milk in the following particulars : i. liuman milk forms finer coagula COAGULATED PROTEIDS. 485 than cows' milk and sometimes not at all with rennin. 2. In human milk the casein yields a very imperfect precipitation with acetic acid, which is a finely flocculent precipitate as compared with the coarsely flocculent precipitate yielded by cows' milk. The casein can be completely precipitated from human milk only by saturation with MgSOj, and not with acetic acid. 3. Casein from human milk is less soluble in water than that of cows' milk. When digested with gastric juice casein yields caseoses instead of albumoses, and coagulated proteids. COAGULATED PROTEIDS. 828. Very little is known of the chemical characteristics of the proteids after coagulation. These products are produced by heating solutions of the proteids, generally in slightly acid solu- tions, or by the action of various agents which have been mentioned above. They are insoluble in water, dilute acids, alkalies and neutral saline solutions of all strengths. They are soluble only in strong acids or alkalies, though often the pro- longed action of dilute acids or alkalies will effect some solution, especially at a high temperature. During these solutions, how- ever, a destructive decomposition takes place, some acid- or alkali- albumin always being produced, together with some peptone and allied substances. The coagulated proteids are readily converted into peptones, at the temperature of the body, by the action of the gastric or the pancreatic juice. All proteids in solutions are precipitated by alcohol. If the alcohol be rapidly removed, the proteids are again soluble in water; but if the precipitate be left in contact with the alcohol for some time, it loses its solubility. Fibrin, is a white, elastic, more or less fibrillated solid, in- soluble in water or dilute salt solution. Soluble in acids (i to 5 per cent.) with difficulty. With strong hydrochloric acid, it forms a violet solution. When boiled with caustic alkaline solu- tions, it forms ammonia and alkaline sulphides. Fibrin may be prepared by whipping blood with a bundle of twigs, and washing the coagulum with water and then with alcohol and ether. It is doubtful whether fibrin is a single substance or whether there are several. The solubilities and behavior of fibrins depends very much upon the conditions of their formation. When un- boiled fibrin is washed until it is white, and digested by active trypsin, it is largely converted into coagulable proteids during the first stages of the digestion. These proteids are globulins, one of which is closely related to paraglobulin, as its saline solu- 486 MEDICAL CHEMISTRY. tions coagulate at 75° C. (167° F.). A second globulin, the product of trypsin digestion, coagulates at 55 to 56° C. (131 to 132.8° F.), and in this respect closely resembles fibrinogen. Globulins are also produced by the action of pepsin in the first stages of its action upon raw fibrin. If the fibrin is boiled or treated for some time with alcohol before digestion with trypsin or pepsin, mere traces, if any, of these globulins are obtained. It is possible, therefore, that the globulins obtained by this treat- ment may be present in the raw fibrin, existing as such. When boiled with water or treated for some time with alcohol, fibrin loses its elasticity, its solubility in the various reagents is lessened and its digestion with pepsin and trypsin is rendered more diffi- cult. It resembles the other coagulated proteids. Fibrin has the peculiar property of decomposing hydrogen peroxide. Pieces of fibrin placed in this fluid seem to undergo no change, but decom- pose the HjOz. Guaiacum- is turned blue by fibrin in the pres- ence of H2O2 or turpentine, in this respect giving the reaction for blood with this reagent. In comparing globulin, myosin and fibrin, they form a series in which myosin is intermediate between the globulin and fibrin in its solubility and most of its reactions. Myosin is in fact, a somewhat more soluble form of fibrin, depositing in clumps or masses instead of in threads or filaments. ALBUMOSES AND PEPTONES. 829. When any of the proteids above described are submitted to the digestive action of pepsin, trypsin or certain other en- zymes, certain intermediate products are produced in the earlier stages, which finally become peptones. When the digestive fluid employed is pepsin with dilute HCl (two per cent, solu- tion), a small portion of the proteid may be first converted into acid-albumin. This product may be obtained by neutral- izing such a digestive fluid in the early stages of the digestion. At a later stage of the digestion, this acid-albumin disappears, and a considerable amount of para-peptone is formed, and other products make their appearance which are known collectively under the name of albumoses. By the continued action of pepsin and hydrochloric acid, these albumoses are changed into peptones as a final product. No further change takes place under the action of pepsin. If trypsin be employed in the digestion of the proteids, in alkaline solutions (.25 per cent. NazCOs), the decomposition of ALBUMOSES AND PEPTONES. 487 the proteid is much more complicated, than is the case with pep- sin. Instead of acid all)umin, a small quantity of alkali-albumm is at first formed, together with more or less coagulable globulin. Soon albumoses make their appearance, which are somewhat rapidly converted into peptones, some of which, in turn, are converted into leucin, tyrosin and other products. Similar products of decomposition may be produced by the action of acids and alkalies alone upon proteids. The character of the products depends upon the concentration of the acid, the tem- perature and the duration of the action. Proteids may also be peptonized by the action of water at a high temperature and under pressure. The albumoses are thus the true primary products of the action of enzymes upon pro- teids and are themselves changed by the same ferments into pep- tones. According to Kiihne, there must be at least two albu- moses, called by him antialbumose and hemialbumose. . Antialburaose may be converted into a peptone by further action of pepsin, and still more readily by the action of trypsin, so that it is not found in the prolonged action of either peptic or tryptic digestion. The peptone into which it is converted he calls antipeptone, for it does not yield leucin and tyrosin with trypsin. Antialbumose differs from parapeptone by the fact that the latter can only be peptonized by trypsin, while the former by either pepsin or trypsin. Hemialbumose is the other product into which albumin, or proteid is split by the action of digestive ferments. It is also met with in the body elsewhere than in the dig'estive solutions. It has been found in the urine, and is probably a product that was formerly frequently reported under the name of peptone. It has also been found in the marrow of bones and in the cerebro- spinal fluid. It is best prepared by the action of a small amount of very active pepsin on a large amount of fibrin previously treated with 2 per cent, of HCl at 40° C. (104° F.). Under the action of pepsin the fibrin liquefie.s, and, as soon as this is complete, dilute NajCOj is added until the reaction is faintly alkaline, when the acid albumin is precipitated. This is removed by filtration, and the filtrate contains hemialbumose with but a faint trace of pep- tone. Hemialbumose may be precipitated from this solution by strongly acidifying with acetic acid and saturating the solution with NaCl. The hemialbumose, as thus precipitated, may be collected on a filter and washed with a saturated solution of NaCl. It may again be dissolved in water if desired. Pure 488 MEDICAL CHEMISTRY. hemialbumose is not readily soluble in water. It is soluble in traces of both acids and alkalies and in weak solutions of neu- tral salts. Hemialbumose is probably not a single substance, in fact it has been pi oven that it consists of at least four closely allied albumoses, protoalbumose, deuteroalbumose, heteroalbu- mose, and dysalbumose, which differ from one another by slight difference in solubility. Decomposition of Proteids by Digestive Ferments (Enzymes). Albumin 1 Antiallnimose 1 Hemialbumose i Antipeptone Aiitipeptone Hemipeptone Hemipeptone Leticin Tyrosin Leucin Tyros Solutions of albumoses give the following reactions : First. Acetic or nitric acid added drop by drop precipitates the solution in the cold, the precipitate dissolving on warming to separate again on cooling. Second. If the solution be slightly acidulated with acetic acid, avoiding all excess, and a trace of potassium ferrocyanide be added, a precipitate forms, which disappears on warming to reappear again on cooling. Third. On adding caustic soda in excess and a drop of a copper sulphate solution the biuret reaction is obtained. This reaction is also obtained with solutions of peptones, but not with other soluble proteids. (See Table, p. 477.) 830. Peptones. — The gastric, pancreatic, and probably the intestinal juices convert albuminous bodies into a more soluble and diffusible form, called peptones. Several different peptones have been described, but some of them are probably mixtures of partially peptonized albuminoids and true peptone ; since the conversion is a gradual process of hydration, it is but natural to expect such a mixture. Dehydrating agents or simple heat can reverse the process, and convert peptone into albumin. It seems certain that the first action of gastric juice is to produce two bodies closely resembling, if not identical with syntonin (acid albumin). These are further changed into two kinds of peptone, named by Kiihne hemipeptone and antipeptone. The reactions of peptones are mostly negative. Solutions of peptone do not exhibit a viscid character, are not coagulated by heat, nitric acid, or acetic acid and potassium ferrocyanide. Alcohol precipitates it, but the precipitate is soluble in water. Tannin, mercuric chloride, picric acid, and potassio-mercuric iodide precipitate it. THE COLLAGENS. 489 The most marked property is its extreme solubility in water, and its ready difFusibility through animal membranes. Amyloid matter is not converted into peptone by pepsin or trypsin. Peptones may be separated from albumoses by saturating the solution with ammonium sulphate, when the albumoses are pre- cipitated, while the peptones are not. Notwithstanding the formation of peptones in considerable quantities, during stomach and intestinal digestion, very little can be found in these localities at any time. They are probably absorbed as soon as formed. It is also a matter of interest, that they disappear as soon as absorbed, and are converted back into other proteids as soon as they enter the blood, or in passing through the mem- branes. It is believed that this change is produced by the tissue cells of the mucous membrane or of the villi. 831. Lardacein, or Amyloid Matter, is an amorphous, friable mass, occurring in certain regions of the body as a patho- logical product. It seems to be a derivative of fibrin. It is generally found as little transparent grains, or corpuscles, some- what resembling starch granules. The usual locations are the liver, spleen and kidneys. It gives many of the proteid reac- tions. It is stained a reddish-brown color with iodine, which is changed to a violet or blue tint by dilute sulphuric acid. Anilin violet stains it rose-red or violet instead of blue. Eosin stains it a bright red color. THE COLLAGENS. 832. Collagen is the name given to the substance composing white elastic tissue of the skin, tendons, etc. When boiled for some hours with water, it forms gelatin. Collagen and ossein seem to be closely allied in both composition and properties. Ossein is the proteid basis of bones, and is converted into gela- tin by boiling with water. Embryonic tissues when boiled, yield mucin and chondrin instead of gelatin. Gelatin in the pure state, is a colorless or slightly yellowish, transparent, vitreous, tasteless mass. It swells in cold water, and readily dissolves in hot water or glycerin, forming a thick, viscid solution, which sets or gelatinizes on cooling. Heating to 140° C. (284° F.) or long continued boiling destroys this power of gelatinizing. It is soluble in dilute acetic and other acids, but insoluble in alcohol, ether and oils. Solutions of gela- tin dissolve copper oxide with a blue color, which, on boiling is reduced, but without separation of red oxide ; it therefore in- 42 490 MEDICAL CHEMISTRY. terferes with the copper test for glucose. An impure gelatin pre- pared from animal refuse (bones, hides, etc.), when in the dry state, forms glue. Liquid glue is a solution of glue in acetic acid. Solutions of gelatin are precipitated by tannic acid, mer- curic chloride, alcohol and chlorine water, but not by acetic acid and potassium ferrocyanide, alum, or acetate of lead. Gelatin is laevorotatory. Chondrin exists in permanent cartilages, and forms gelatin on boiling with water. The gelatin from this source differs slightly from that obtained from collagen, or ossein. Mucin occurs in the cement substance of connective and epithelial tissues. It is also present in bile, and secretions of mucous membranes. To prepare it from bile, precipitate with alcohol, dissolve the precipitate in lime water, precipitate again with acetic acid, filter, and wash with alcohol or ether. It swells up in a little water, and dissolves in a large quantity. Its solutions do not coagulate on heating, and it contains no sulphur. It is insoluble in alco- , hoi, ether, chloroform, or gastric juice. Its solutions are precipitated by acetic acid, alum, basic acetate (sub-acetate) of lead, and very dilute mineral acids. Its solu- tions dissolve oxide of copper, and thus hinder the copper test for sugar, when applied to urine conlaining an abundance of mucus. Clastin. This is the characteristic component of elastic tissue, after the removal of gelatin, mucin, fats etc. It is usually prepared from the ligamentum nuchse of the ox, which is cut into fine slices, boiled for three or four days in water, and then for some hours with i per cent. KOH solution, and finally with water. This is then repeated with lo per cent, acetic acid, and finally it is treated 24 hours in the cold with 5 per cent. HCl, washed with water, boiled with 95 per cent, alcohol and exti-acted for at least two weeks with ether to remove the fat. There is left a pale yellowish powder, in which the fragments of the original elastic tissue may be distinguished under the microscope. When moist it is yellow and elastic, but on drying becomes brittle. It may be digested with pepsin or trypsin and is readily corroded and dissolved by papain. Keratin. This is the chief constituent of the hair, nails, feathers, horns and epidermal structures in general. It is mixed however, in these structures, with small quantities of proteids and other substances, from which it may be freed by thorough extrac- tion with Water, alcohol, ether and dilute acids, followed by VEGETABLE PROTEIDS. 4gi digestion with pepsin and trypsin. The composition of keratin is closely allied to that of the true proteids. Neuro-keratin is an allied substance found in brain tissue. Chitin, C15H2SN2O10, is not found as a constituent of any mammalian tisssue, but is found in the exoskeleton of many in- vertebrates. It is more analogous to the cellulose of plants than to the proteids. The most convenient source is from the shell of crabs and lobsters. Nuclein is the name given to the material of which the nuclei of plants and the nuclei of cells are composed. When pus or yeast cells, or red blood corpuscles, yolk of egg or salmon eggs are extracted with water and dilute HCl, the cells are broken up and dissolved and the nuclei separated from them. By treatment of the solution with alcohol and ether, and final digestion with pepsin, the substance of the nuclei is not affected. The residue obtained from this digestive solution is a sub- stance called nuclein. When prepared pure, it is an amorphous substance, rich in phosphates, which is set free as phosphpric acid when it is boiled with alkalies. At the same time a proteid is produced, as one of the products of the decomposition. Adenin has been obtained by the treatment of the nuclei of the yeast cells with hot, dilute H^SO,. When casein is digested with pepsin a residue of nuclein is left, and it appears likely that casein may be a compound of nuclein with a proteid, or a substance that has been called nucleo-albumin. Egg yolk is also believed to contain nucleo-albumin. Synovial fluid is also stated to con- tain a similar substance. VEGETABLE PROTEIDS. 833. The amount of proteid matter in plants is less than in animals. They do not diifer essentially in composition or properties from those found in animals. They occur in solution in plant juices, or as composing the protoplasm of the cells, or deposited in the form of granules (aleurone grains.) Plant proteids have received less attention than the proteids of animals. Representatives of each of the same five or six classes of proteids above mentioned are to be found. Vegetable albumins are sparingly found. The most of the proteid substance found dissolved in plant juices, and precipi- tated by boiling, is globulin and not albumin. Plant globulin or plant vitellin is the most abundant pro- teid found in plants. This globulin, like animal vitellin, is in- 492 MEDICAL CHEMISTRY. soluble in water, and soluble in saturated solution of NaCl. It coagulates at about 75° C. (167° F.). This substance, as it occurs in aleurone grains of many plants, is distinctly crystalline. It is thus the purest native proteid known. Plant myosin and paraglobulin have also been found. Of the vegetable albuminates the two best known are legumin or vegetable casein, and conglutin of almonds and lupines. Legumin occurs in the leguminous plants, as an alkali albu- ininate. It may be obtained from softened peas or beans. It resembles casein in its properties. Some recent investigators claim that it does not occur as an alkali albuminate in the plant, but as a globulin, which is changed into an albuminate by the method of extraction. Like all the globulins, it is easily soluble in alkalies and acids. Proteoses or Albumoses. — Several plants contain proteids of this class. Martin has described four proteoses found in papaw juice, and two in wheat flour. In the papaw they are as- sociated with the ferment papain, and are probably produced by the action of this ferment upon the globulins of the plant. Papain acts upon animal proteids in alkaline or weak acid solu- tions, to convert them into proteoses and finally into peptones. It does not form peptone wiih vegetable proteids. Leucin and tryosin are formed, however, in small amounts. Peptones, for the above reason, do not occur in plants. Coagulated proteids of vegetable origin are produced by heating the plant, when the albumins and globulins are coagu- lated. The fibrin-like body formed from wheat flour, by treat- ment with water, and frpm which the starch may be washed with cold water, is a compound or mixture of two proteids found in the flour. The proteids in wheat compose about ten per cent, of the weight of the grain. The most recent investigations show that there are four different proteids present. An albumin existing in from o 3 to 0.4 per cent, of the weight of the grain, a globulin in from o 6 to 0.7 per cent., a proteose in about 0.3 per cent., gliadin existing in 4.25 per cent., and glutenin (gluten casein; in 4.5 per cent, of the grain. Gluten fibrin or gluten is principally made up of a mixture of the last two of these bodies. Gliadin is soluble in pure water, but in the presence of the salts of the flour, it forms a sticky, tenacious mass which adheres to the glutenin, which is insoluble, forming a tough glutinous mass inclosing starch to form a dough. By washing or kneading this dough with cold water, the starch may be washed THE PRINXIPAL ANIMAL PIGMENTS. 493 out together with the other proteids, and gluten is left. Some investigators have claimed the presence of a ferment, while no one has ever isolated it, and some deny its presence or the necessity for it, in the formation of gluten. Gluten is soluble in weak alkalies and acids, and it forms peptones with gastric and pancreatic digestion. THE PRINCIPAL ANIMAL PIGMENTS. BLOOD PIGMENTS. 834. The haemoglobins, or blood pigments, form the chief constituent of red blood corpuscles in vertebrates, and occur in the muscle of mammals, and in the blood of a few of the inver- tebrates.. They all crystallize, but not with equal facility. All haemoglobins are of a blood-red or brick-red color when in pow- der. They contain from .4 to .6 per cent, of iron, and differ slightly in composition. The crystalline forms of haemoglobins vary in different-ani- mals. The crystalline blood pigments are oxyhaemoglobins. Haemoglobin forms a feeble compound with oxygen, which it releases by heating its solutions in a vacuum, or in presence of ferrous sulphate, ammonium sulphide, stannous chloride, etc. Reduced haemoglobin and oxyhaemoglobin are distinguished by their absorption spectra, the latter showing two such bands sepa- rated by a green band, while the former shows but one broad band occupying nearly the position occupied by the greenish- yellow band between the dark ones above mentioned. (See Figs. 10 and II, Frontispiece.) Haemoglobin unites with nitric oxide, carbon monoxide, hydrochloric acid, hydrocyanic acid, carbon dioxide, etc. Some of these compounds give peculiar spectra; these gases are not easily expelled by oxygen, and hence are deadly poisons when inhaled. Haematin, Ca^Ha^NjFeOj, is obtained in the form of a salt, by the decomposition of oxyhaemoglobin with an acid. It is an amorphous, blue-black mass, with a metallic lustre, insoluble in water or alcohol, but soluble in alkalies. It yields two different spectra ; one with oxygen, and another with carbon dioxide. Haematin Hydrochlorate, or haemin crystals, may be obtained by heating haemoglobin, or dried blood, with common salt and glacial acetic acid. It forms thin, rhombic plates, having a brown-red color. The formation of these blood crystals is used to detect blood stains in criminal cases. The drop of dried blood is placed upon a microscopic slide, together with some 494 MEDICAL CHEMISTRY. pulverized common salt, and then treated with glacial acetic acid, and a cover glass placed upon it. The slide is heated until bubbles appear in the acid, cooled, and examined with a }^ inch objective. The presence of blood is indicated by the presence of the crystals. The amount of haemoglobin in the blood is most easily deter- mined, for clinical purposes, by the haemoglobinometer. The process depends upon the imitation of the color of a standard solution of hgemoglobin, by dilution of a measured volume of blood until its color is that of the standard solution. Of course the solutions must be examined by transmitted light, and the examination tubes must be of the same diameter, so as to examine the solutions in layers of equal thickness. By observ- ing the degree of dilution of the blood, its depth of color relative to the standard may be determined. The actual contents of the standard, in haemoglobin, being known, the haemoglobin in the blood or other fluid may be calculated. Other methods are used, but this one, known as Gower's, is the simplest and best for clinical purposes. Methxmoglobin is a slightly changed derivative from oxyh£Emoglobfn, pro- duced by the action of many reagents, as acids, alkalies, many salts, etc., or by simply exposing '^ * pigment derived from haemoglobin by dissolving it in strong HjSO^, or by heating it with HCl. By diluting this solution with water the coloring matter is thrown down, especially in neutralizing the acid. This pigment occasionally appears in the urine, as urohsematoporphyrin or urohsematin. Haematoidin, CjgHjgNjOj, occurs as reddish, rhombohedral crystals in old blood clots, in corpora lutea and in the urine in cases of haematuria. It is believed to be identical with bilirubin, and shows the origin of bilirubin to be probably in the decomposed or disintegrated blood pigment, separated by the liver. BILIARY COLORING MATTERS. 495 BILIARY COLORING MATTERS. 835. There are two pigments obtainable from bile and biliary calculi, viz. : bilirubin and biliverdin. Bilifuscin, bilipra- sin, bilicyanin, choletelin, bilihumin and hydrobilirubin have also been described. The principal one of these, and probably the only one contained in bile when first secreted, is bilirubin, from which the others are derivatives. Bilirubin, CisHisNjOs, is met with in the free state, in the bile of man and the carnivora, and ox bile ; also, together with bilifuscin, QsHjoNjOi, and biliprasin, C16H22N.2O5, in combina- tion with calcium, in biliary calculi. It is probably identical with the red crystalline matter of old hemorrhagic clots, called hematoidin, and with biliphaein, bilifulvin and cholepyrrhin. It may be prepared by treating the powdered biliary calculus first with ether, then with boiling water slightly acidified with hydrochloric acid. The residue is washed with pure water, dissolved in hot chloroform and filtered. The chloroform is dis- tilled off from the filtrate and the residue treated with absolute alcohol and ether, by which the bilifuscin is removed and bili- rubin left. By dissolving this residue in chloroform and setting aside, a part of it may be obtained as a dark-red crystalline powder. It also exists as an orange-red, amorphous powder. It acts the part of a weak acid, combining with sodium, cal- cium, barium, lead etc. Formula of the calcium salt, (CjsHnNj- OjCa. Bilirubin is closely related to haematin, a derivative of haemo- globin. This is its probable source. G„H3,N.FeOs + + H^O = CO,C3,H3, + CO, + Fe(OH),. Moderately strong nitric acid, added to an ammoniacal solution of bilirubin, first colors it green, then blue (bilicyanin), violet- red and finally yellow. (Gmelin's test for bile.) Nearly the same series of colors are produced by adding bromine to the chloroform solution, with the exception that it finally becomes colorless. Nascent hydrogen converts it into hydrobilirubin, CajH^NiOj (urobilin of urine, stercobilin of fseres). Hydro- bilirubin, is a dark-brown amorphous powder, soluble in alkalies, sulphuric and acetic acids, alcohol, ether and chloroform.. It does not give the play of colors with nitric acid. It is probably formed in the faeces by the action of the nascent hydrogen, set 496 MEDICAL CHEMISTRY. free by the butyric and putrefactive fermentations, upon bili- rubin. Biliverdin, CieHjoNjOs (or CisHiaNjOi), is an oxidation pro- duct of bilirubin, and is readily formed by exposing alkaline solutions of this pigment to the air, or by similar treatment of fresh bile.. It forms a green, amorphous powder, insoluble in water, ether and chloroform. It is soluble in alcohol, acetic acid and alkaline solutions, and reacts with nitric acid as does bili- rubin. Hydrobilirubin may be prepared from it. Biliprasin, CijHjzNjOs, is found in human gall-stones, and bilifuscin, CieHjoNzOi, occurs in small quantities in old bile, and in gall- stones. According to Stadeler, biliverdin is bilirubin -f- O and H2O. Biliprasin is biliverdin -f HjO. Bilifuscin is bilirubin -{- H2O. Viewed in this light these various pigments would appear to be formed in the following order: Haemoglobin, hsematin or haematoidin, bilirubin, hydrobilirubin (urobilin), bilifuscin, biliverdin and biliprasin. Fuscin (retinal melanin) is found in the retinal epitheliurri, Lipochrin and chromophanes are found in the fat globules in the retinal epithelium. Visual-purple is also found in the retina of all vertebrates. Pyocyanin is the green or blue color of pus. 836. Urinary Pigments. — Besides urobilin, the urine con- tains at least one and possibly more, coloring matters. Uro- xanthin or indigogen, is a normal constituent of urine, but is much increased in the first stage of cholera, and in carcinoma of the liver. According to some authors, this coloring matter is identical with indican. Uroxanthin may be detected in urine by adding to the urine its own volume of hydrochloric acid, and a few drops of a solution of chloride of lime j the solution is colored red, violet, green, or blue, according to the amount of uroxanthin present. In some cases this test succeeds with hydrochloric acid alone. In some cases the urine containing uroxanthin becomes blue, on standing for some days, from spontaneous putrefaction. Urobilin may be detected in fever urines by making them alkaline with ammonia, filtering, and adding a few drops of zinc chloride solution, when it will show a green fluorescence. This urobilin reaction may be obtained more distinctly by shaking the urine with ether, separating the ethereal solution, and, after evaporating the ether, dissolving the pigment in absolute alcohol. This solution will usually show the green fluorescence. Uro- chrome (Thudichum), uromelanin (Thudichum), uroery- IMPORTANT VEGETABLE COLORING MATTERS. 497 thrin, and other pigments have been described, but the whole subject is enveloped in much uncertainty and confusion. Black urine is occasionally seen after breathing arseniuretted hydrogen, in carbolic acid poisoning, and after inunctions of tar. Melanin (Melanogen), is the black pigment of the choroid, melanotic tumors, and skin of the negro. Pathologically, it is found in the urine of persons suffering with melanotic cancer, and sometimes with malaria. It is sometimes deposited in the lungs. Urine containing melanin turns dark on exposure to the air, or, more rapidly, with oxidizing agents, as nitric or chromic acids. Its detection is useful to the physician, as an aid to the diagnosis of melanotic cancer of liver, etc. IMPORTANT VEGETABLE COLORING MAT- TERS. 837. Indigo is a blue coloring matter derived from several species of Indigofera, and other plants growing in India, Africa and South America. It exists as a glucoside, called indican, which is extracted with water ; the liquid allowed to ferment in the air, deposits the indigo as a blue powder. Com- mercial indigo is a mixture of several bodies containing about 50 per cent, of indigo-blue or indigotin, CieHioN^Oa. (See p. 448.) In dyeing with indigo, the goods are steeped in indigo- white, and then exposed to the air, when indigo-blue is deposited in the cloth. Indigotin has been prepared synthetically from toluene, C-H,, a homologue of benzene. Litmus is a purplish-blue coloring matter obtained from lich- ens ; generally from Lecanora tartarea, by steeping in urine, and adding lime and potassium carbonate. The mixture is exposed to the air for a few weeks, with frequent stirring, when a thick, blue solution is obtained. The solution is thickened up with plaster-of-Paris or chalk, formed into cakes, and cut into little cubes. The coloring matter of litmus is a weak acid forming salts having a blue color, the commercial product being the potassium salt. With acids it becomes red, from the liberation of the acid. Turmeric is the root of Cucvrvia longa; it yields a j'ellow tincture, which turns brown with alkalies. It is used to a large extent to give a yellow color to various articles of food, as mustard, chow-chow, vermicelli, etc. SafTron is the stigmas of the flower of Crocus sativa. It yields 498 MEDICAL CHEMISTRY. to dilute alcohol, a yellow coloring matter called polychroit, C^HeoOis, or a glucoside of crocin, QeHigOs. Tinctura croci is ofificial (U. S. P.). Saffron is used to color certain articles of food, as butter, cheese, macaroni, etc. Annatto is a yellow color, obtained from the seeds of Bixa orellana. It is used in coloring butter, milk, cheese, etc. Logwood, the wood of Hematoxylon, contains a purple dye, hematoxylin, used for purple and black dyes. It is ofificial, and is used as a tonic and astringent. Brazil wood furnishes red dyes and lakes. Cochineal, the female of the insect Coccus cacti, yields to boiling water and alcohol, a beautiful, red color- ing matter, which precipitated with alum and an alkaline carbo- nate yields carmine. Chlorophyll is the name given to the green coloring matters of the leaves of plants. It occurs as microscopic granules distributed through the cell protoplasm in all the green portions of the plant. It may be extracted with alcohol, ether and benzene. Very little is known of this body, but it seems to be composed of two coloring matters, a blue and a green. It contains iron, and possesses the power, under the influence of sunlight, of decomposing CO, and uniting the carbon to the elements of water. The yellow color of autumn leaves is due to xantho- phyll, an oxidation product of chlorophyll. POISONS AND THEIR ANTIDOTES. 838. Of the emergencies which arise in every-day life, or even in the practice of the young physician, none are more embar- rassing than acute poisoning. The word poison, to many people, carries with it an idea of horror and panic. The pharmacist is often consulted in haste, or may be called upon to render tem- porary aid until the services of a physician can be secured. He may in such cases render great service by administering the pro- per antidote, and thus saving valuable time. Even the physi- cian is liable to something akin to alarm, when he comes into the presence of a victim of a violent poison. It is for these reasons that we introduce a few of the most common poisons, with their antidotes. We do not intend to give a guide to the treatment of cases of poisoning, but merely a few simple rules to be remembered as first aids to those suffering with acute poi- soning. POISONS AND THEIR ANTIDOTES. 499 The first thing to be considered is, the symptoms of poisoning. Not unfrequently persons claim to have taken poison, when such is not the case. Or, .suspicious friends fear that poison has been taken. The author has often met with cases of this kind, where a knowledge of the symptoms of poisoning has saved the patient a very disagreeable experience, and the physician a great deal of trouble and future chagrin. The physician should be familiar with the nature and action of poi- sons, the symptoms which they produce, the circumstances which retard or otherwise modify their action, their chemical and physiological antidotes, the pathological changes they induce, and the methods of combating these results. It is our purpose, here, to name a few of the symptoms of poisoning, and then to offer a few hints as to antidotal treatment. The chief characteristics of poisoning are, more or less severe symptoms coming on suddenly, or within a fe-w hours after taking some substance or fluid into the stomach, the individual being previously in a state of health. These symptoms usually increase steadily and uni- formly, and tend to prove rapidly fatal. The symptoms may be greatly varied as to time and severity, by the quantity or form in which it is administered, the state of the stomach — whether full or empty — the condition of the person — ^wtether asleep or awake — and a certain idiosyncrasy of the individual. The symptoms which should arouse suspicion of acute poison- ing are, the sudden onset of pain in the region of the stomach of a healthy person, especially of a "burning pain," accom- panied by dryness of, or a metallic taste in the throat, more or less vomiting, great prostration of the vital powers, a deathly or cadaveric aspect, or an expression of great fear or concern, the rapid intervention of coma, and speedy death. If all, or the greater number of the above symptoms are present in any case, there is reason for suspicion, and the physician should govern himself accordingly. (See remarks under Arsenic, Art. 235.) Poisons may, for convenience, be divided into the following five classes, based upon their effects upon the human subject : ist, Corrosives ; 2d, Irritants ; 3d, Neurotics ; 4th, Septic Poisons ; 5th, Gaseous Poisons. 839. Corrosive Poisons. — To this class belong those poisons which exert, principally, a local action upon the tissues with which they come in contact. The most important of this class are cor- rosive sublimate (HgCIj), the concentrated mineral acids (sul- phuric, hydrochloric, nitric), and oxalic acid ; the alkalies and 500 MEDICAL CHEMISTRY. their carbonates (potassium, sodium, and ammonium hydroxides and carbonates) ; corrosive sahs, as bisulphates of the alkaline metals, alum, nitrate of silver, chloride of zinc, butter of anti- mony (SbClj). Carbolic acid is a violent corrosive, when con- centrated, and also has a remote effect upon the system after being absorbed. The symptoms of corrosive poisoning follow immediately after taking the poison, and are a sense of acid, alka- line, or metallic, burning pain in the mouth, throat, gullet, and stomach, usually inducing vomiting, which, however, does not relieve the distress. The pain soon extends over the entire abdomen, and is accompanied with symptoms of shock, or col- lapse. There may be staining of the fauces or mouth. 840. Irritant Poisons.- — Irritant poisons give rise to pain in the stomach, of a burning character, usually coming on some minutes or hours after taking the poison. In this respect, they differ in their action from the corrosives. The pain is accom- panied, or followed, by vomiting, faintness, purging, and tenes- mus; the evacuations being often tinged with blood. The pulse is weak or irregular, and there is frequently severe headache. Death is usually caused by collapse, convulsions, or by inducing severe inflammations, which wear the patient out, after a variable period of time. Some have, also, a specific physiological action, besides their irritant action. The following are the more com- mon irritants: Dilute mineral acids, concentrated organic acids, lime, zinc, copper, barium, silver, and mercuric salts ; all com- pounds of arsenic and antimony ; phosphorus, iodine, bromine, etc. Many kinds of food may, under certain conditions, become irritant poisons. Meat, fish, lobsters, tomatoes, etc., especially after having been canned and then exposed to the air. (See Ptomaines.) 841. Neurotic Poisons. — The neurotics exercise their ac- tion through the nervous system, and, therefore, only after absorption into the circulation. They rarely exert any local action. The neurotics are sometimes subdivided as follows : — . Examples Narcotics, or those producing sleep, Opium. Anaesthetics, or those producing insensibility, Chloroform. Inebriants, or those producing intoxication, Alcohol. Deliriants, or those producing delirium, Hyoscyamus. Convulsives, or those producing spasms, Strychnine. Hyposthenisants, or those producing death by syncope, . . . Prussic acid. Depressants, or those producing marked depression, .... Nicotine. 842. Septic Poisons. — To this class belong certain poisons TREATMENT OF ACUTE POISONING. 50I introduced into the body through abrasions of the skin, open wounds, or by the fangs or sting of venomous animals or insects. In many respects these poisons resemble, in their action, the dejiressing narcotics. 843. Poisonous Gases. — -To this class belong carbon mon- oxide (charcoal fumes), carbon dioxide (choke damp), marsh gas (fire damp), illuminating gas, hydrocarbon vapors, sewer gas, confined air of living apartments, and noxious gases and vapors from manufacturing establishments. TREATMENT OF ACUTE POISONING. 844. In every case of acute poisoning, or where the symptoms and circumstances indicate that a poison has been taken, the following is the course to pursue: — 1. Get the poison out of the system as soon as you can, unless it be a caustic. 2. Neutralize what you cannot remove. 3. Favor the natural elimination of the poison. 4. Combat any dangerous symptoms as they arise. The first of these steps may be secured in one of three ways ; viz. : by the use of emetics or the stomach pump or the stomach tube. If a stomach pump is not at hand, or in case corrosives have been swallowed and there is danger of doing damage in inserting it, the stomach tube may be introduced through the mouth or even through the nose. By attaching a funnel to the upper end of this, tepid water may be run into the stomach. On now turning the person upon his face or lowering the end of the tube, it acts as a siphon to run the water out. Repeat this process several times as in the process of lavage or until you are sure all poison is removed from the stomach. In the absence of a funnel, make as a substitute a cup-shaped cavity about the upper end of the tube with wax, putty, or even wet clay. The proper antidote or an emetic may be dissolved in the water used. THE PRINCIPAL EMETICS. 845. Zinc Sulphate. — Give 20 grains at once, or dissolve 353 in two ounces of water, and give tablespoonful every 15 minutes. Copper Sulphate. — 5 grains every 15 minutes, or, still better, 10 grains at once, followed by tepid water. Alum. — A tablespoonful, given in syrup or honey. 502 MEDICAL CHEMISTRV. Mustard (ground). — A dessertspoonful, stirred in tepid water and quickly swallowed. Very efficient, and is somewhat stimu- lating. Apomorphine.— Give Jg- grain hypodermically. Spr. Ipecacuanhae. — Used mostly for children. Is depres- ing. fgj every 15 minutes to a child two years old, until emesis is produced. Tepid Water. — Drink copiously and until emesis occurs. It may be assisted by tickling the throat with a feather or the ex- tended finger. Common Salt. — A tablespoonful in a pint of lukewarm water is often effectual. SPECIAL POISONS AND THEIR ANTIDOTES. THE CORROSIVE POISONS. 846. Strong Mineral Acids. — Sulphuric, hydrochloric, nitric. Symptoms. — Staining of mouth or throat : immediate pain ; vomiting ; great prostration. Antidotes. — Chalk, lime water, whitewash, magnesia, plaster from the wall, baking-soda, soap. Then give oil freely, and mucilaginous drinks. Do not give emetics or use stomach- pump. All antidotes must be well diluted before they are given. Corrosive Vegetable Acids. — Oxalic, tartaric, acetic. Syinptoms. — Burning pain, constriction in throat, and usually vomiting. Extremities cold ; countenance livid. Antidotes. — Same as for mineral acids except in the case of oxalic acid. When this acid is suspected to have been taken, use lime water or chalk only. Then give mucilaginous drinks, and stimulants. Carbolic Acid (Phenol) and Creosote. — Symptoms. — Pain in stomach and whitened stains; odor; contracted pupils ; coma; death by collapse. Treatment. — Oils, then emetics or stomach-tube, unless the quantity taken was large and in the pure state. A mixture of olive and castor oils with magnesia in suspension. Albumin of eggs given freely. Treat the collapse by injecting stimulants. Caustic and Carbonated Alkalies. — Symptoms. — Acrid, burning taste in mouth, throat, oesophagus, and stomach ; hoarse- ness; dyspnoea; vomiting of blood and mucus; surface clammy ; pulse rapid ; pain over abdomen, and diarrhoea. SPECIAL POISONS AND THEIR ANTIDOTES. 503 Treatment. — Well-diluted vegetable acids, such as vinegar, lemon juice, tartaric or citric acids ; fixed oils, such as castor, linseed, olive, oi: cod-liver oil. Mucilaginous drinks may be given freely. Do not give emetics or use stomach-pump. IRRITANTS. For general symptoms, see Art. 838, page 499. 847. Antimony — Tartar Emetic — Wine of Antimony, or Oxide of Antimony. — Symptoms. — Metallic taste ; nausea; violent vomiting ; burning heat and pain in stomach ; purging ; cramps, cold perspiration, and great debility. Treatment.^— AsshX the vomiting by draughts of warm water, or mucilaginous drinks, such as flaxseed tea. Then give a cup of strong tea, or an infusion of oak bark, or a solution of tannin. This may be followed by opiates and stimulants. Chloride of Antimony — Butter of Antimony. — Symp- toms. — Same as above, but more caustic. Afitidotes. — Magnesia, with milk and water, baking-soda, tan- nin, as above, for tartar emetic. Potassium Bichromate. — Symptotns. — Violent purging; painful vomiting of yellow vomit ; dilated pupils ; cramps in legs ; great depression. Treatment. — Free use of lime-water, or magnesia in milk. Arsenic — AA^hite Arsenic — Arsenious Acid. — Symptoms. — Come generally within a half-hour, but may be delayed two or three hours. Faintness; nausea; constant vomiting; burning pain in stomach, increased by pressure, and soon extends over abdomen ; headache (frontal) ; diarrhoea ; great thirst ; catching, painful respiration ; quick, feeble pulse ; cold extremities, and anxious countenance. Death by collapse within twenty-four hours. Treatment. — Expel the poison by thorough emesis. Promote the sickness by free use of albuminous or mucilaginous drinks. As an antidote, give raw eggs, beaten up in milk ; freshly pre- cipitated ferric hydrate or ferric hydrate with magnesia. The first is made by mixing together 100 c.c. of liquor ferri ter- sulphatis (U. S. P.) and no c.c. of ammonia water, dis- solved in 1000 c.c. of water. Let settle and wash by decanta- tion, filter through muslin, and shake the precipitate up with 250 c.c. (r tumblerful) of water. Ferric hydrate with Magnesia is prepared by shaking up 10 grnis. of calcium magnesia in a quart bottle with about 800 504 MEDICAL CHEMISTRY. c.c. of water until a smooth mixture is obtained; add 50 c.c. of solution of ferric sulphate and shake again until a uniform smooth mixture is obtained. Solution of dialyzed iron has been used with success. These should be followed by stimu- lants well diluted. Metallic Salts — Alum. — Alkaline bicarbonates, baking- soda. Soluble Barium Salts. — Soluble sulphates, Epsom or Glau- ber's salt. Then give emetics. EMETIC POISONS. 848. Soluble Copper Salts. — Albumin, white of egg and milk, baking-soda, foltowed by an emetic. Iron — Green Vitriol — Persulphate of Iron. — Baking- soda and emetics or stomach tube. Lead — Sugar of Lead, White Lead. — Solution of Epsom or Glauber's salt given with raw eggs. Then give emetics fol- lowed by castor oil. Mercury — Corrosive §ublimate. — Albumin, white of egg, flour and milk, followed by emetics or stomach-pump, unless the poison was taken in a concentrated form. Then do not use the pump. Silver Nitrate — Lunar Caustic. — Common salt, then emetics. Zinc Chloride— Soldering Fluid, Burnett's Fluid. — Baking soda, milk, white of egg, tea, decoction of bark. Give opium to relieve the pain, then emetics if necessary. Tin, Chloride of. — Baking soda, magnesia, milk and white of egg. Iodine. — Most common from the tincture. — Give boiled search paste, made thin enough to drink. In urgent cases use starch or flour, with cold water. Produce vomiting or use the stomach tube. Phosphorus — Rat Poison. — Has no true chemical an- tidote. Magnesia, milk of magnesia, chalk, or lime suspended in gruel ; turpentine. Give no fixed oils. Produce vomiting or use the stomach tube of j)ump. Poisonous Meat, Fish, Lobsters, Etc. — Symptoms. — Nausea and vomiting 3 to 4 hours after taking food, gastro- intestinal irritation, great depression, scarlet rash at times, con- vulsions in young subjects, pupils either dilated or contracted. Recovery usual. SPECIAL POISONS AND THEIR ANTIDOTES. 505 Treaimen/.—EncouTage vomiting by copious draughts of warm water; counteract depression with diluted brandy or whiskey; relieve pain with opium or one of its preparations. Apply hot fomentations to abdomen. When vomiting ceases, give castor- oil or other laxatives. NEUROTICS. 849. Narcotics — Opium, Morphine, Laudanum, Pare- goric, Soothing Syrups, Quieting Cordials, Etc. — Symp- toms. — Appear in 20 to 30 minutes. Commence with giddiness, drowsiness, stupor, insensibility, with slow and stertorous breath- ing, weak pulse, contracted pupils, not reacting with light, sur- face sometimes cold, sometimes bathed in sweat ; countenance livid. There is occasionally vomiting or convulsions preceding death. Treatment. — First empty the stomach of any poison still re- maining unabsorbed, by emetics or the stomach pump or tube. The patient is to be kept awake by forced walking, by the cold douche, or flagellations with wet towels. Faradic electricity may be applied to the spine. Give strong coffee in abundance. Atropine hypodermically, in y^ grain doses, repeated until the pupils show its effects. Anaesthetics — Vapors of Chloroform or Ether, Chlo- ral, Methylene Bichloride, Nitrous Oxide, Etc. — Pure air, cold douches, artificial respiration, hypodermic injections of brandy, aqua ammonias (diluted), nitrite of amyl or nitro-gly- cerin. Galvanism or Faradism may be employed, if the instru- ments are at hand, but are of doubtful benefit. InebriantST— Alcohol, Cocculus Indicus, Nitrobenzene (Essence of Mirbane), Anilin, Etc. — Emetics or stomach- pump, when there is reason to believe that any poison remains unabsorbed, then ammonium carbonate, hydroxide or acetate well diluted. Treat the narcosis as under opium. Hyposthenisants or Syncopants — Prussic Acid (hy- drocyanic acid). Potassium Cyanide, Laurel Water, Peach Pits, Cherry Pits, Plum Pits, Etc. — No chemical antidote. Emetics or stomach-pump, where there is time. Cold effusions to face and neck, inhalations of ammonia ; spirits of ammonia or nitroglycerin should be given internally with brandy. Aconite (Monkshood, Wolfsbane, Blue Rocket).— .^»«//^»2j. — Heat, numbness and tingling in mouth and throat, giddiness, loss of muscular power, sometimes delirium or purging. The 43 5o6 MEDICAL CHEMISTRY. skin is cold, pulse extremely feeble, breathing oppressed. Death by collapse or asphyxia. Treatment must not be delayed. Emetics or stomach-pump. Give castor-oil, animal charcoal, or strong coffee. Stimulants will be needed — brandy, ammonia, nitrite of amyl, nitroglycerin. Artificial respiration if necessary. D ELI RT ANTS. 850. Belladonna (Deadly Nightshade). — Symptoms. — Dry- ness of fauces, thirst, flushing of face, dilatation of the pupil, double vision, giddiness, indistinct vision, delirium and stupor or occasionally convulsions. Symptoms appear in half-hour after dose. Treatment. — Stimulants, emetics ; morphine acts well in some cases. Stramonium (Thorn-apple, Jamestown weed). — Fruit and leaves are poisonous. Symptoms. — Same as belladonna. Treatment. — As in belladonna. Hyoscyamus Niger (Henbane). — Symptoms. — Giddiness, excitement, sense of weight in the head, drunkenness, delirium, dilated pupils, double vision, ending in coma. Treatment. — Stomach-pump, emetics (ZnSO^), stimulants and full doses of castor-oil. NEUROTICS PRODUCING CONVULSIONS. 851. Nux Vomica, Brucine and Strychnine. — Symp- toms. — Intense bitter taste, followed in a few minutes by difficult breathing, stiffness in neck, muscular twitchings, quivering of frame. The head is drawn back, the body arched backward. The face becomes dusky and drawn. Soon there are distinct spasms and great fear of death. Treatment. — Emetics or stomach-pump before spasms, then tannin, tea, oak-bark tea. Keep patient warm and quiet. Chloroform or chloral to control the spasms. DEPRESSANTS. 852. Digitalis (Purple Foxglove), Tobacco, Lobelia, Colchi- cum (Meadow Saffron), White Hellebore. Symptoms. — Those of great depression, vomiting, irregular heart action. Treatment. — Stimulants, emetics (mustard) and purgatives. Use stimulant freely. Wash out stomach if seen in time, or give mustard emetic. SPECIAL POISONS AND THEIR ANTIDOTES. 507 Bites. — First wash thoroughly, then paint with carbolic acid {\ strength), or tincture of iodine. Tie a handkerchief tightly above wound, until the above applications or strong nitric acid can be applied. Give alcohol freely in bites of snake, scorpion, tarantula, etc. Stings. — Extract " stinger," if left behind. Apply mud, or a paste made of baking soda, or wash with weak ammonia water. Poisoned 'Wounds, ") Apply carbolic acid (^ strength"). Dissecting Wounds, >-or paint the wound and around it Infectious Diseases. ) with tincture of iodine. Give stimulants internally. Poisonous Gases — Sulphuretted Hydrogen, Chlorine, Bromine, Carbon Monoxide and Dioxide, Nitrous Fumes, Illuminating Gas, Sulphurous Oxide, etc. — See special gases in text. Treatment. — Fresh air, rest, and mild stimulation. Artificial respiration when necessary. INCOMPATIBLES. 853. Substances are said to be chemically incompatible when, on being mixed together, they react upon each other so as to cause an entire change in the properties of the substances so mixed. They may cause the evolution of a gas, an explosive mixture or compound, a poisonous or very active substance formed from comparatively inert ones, or, a precipitation of one or the other of the ingredients in the new compounds formed. Sometimes two or more substances are brought togelher with the intent of producing a new Substance different from either ; as, 2KI -\- HgClj =^ HgTg-l- 2KCI. This can hardly be regarded as an incompatible mixture. Of physiological and therapeutical incompatibility we shall have nothing to say here. The student will find the following rules of value to him in the beginning: — 1 . A free acid is incompatible with the alkaloids and the metallic hydroxides and carbonates. The three mineral acids displace the organic acids from their salts. The converse of these statements is also true; i. e., metallic hydroxides and carbonates are incompatible with the acids. 2. If two substances, when mixed, can form an insoluble third body, or can react so as to generate a gas, they are incompatible. A knowledge of the. solubility of the ordinary salts is, therefore, of great importance to the physician. For example, lead or barium cannot exist in a solution with a sulphate; silver^ lead, or mercurous mercury cannot exist in a solution with a chloride. Substances are, therefore, incompatible with their tests and antidotes. 3. The alkaline hydroxides and carbonates are incompatible with the salts of the alkaloids and most salts of the heavy metals. 4. Iodides and bromides precipitate most of the heavy metals, and are there- fore incompatible with them. So8 MEDICAL CHEMISTRY. 3. The vegetable astringents and bitters owe their properties largely to their gallic acid and tannin. Tannin and most vegetable astringents precipitate the heavy metals from their salts, and are therefore incompatible virith them. 6. Powerful oxidizing agents (strong nitric acid, potassium permanganate, hydrogen peroxide, chlorine, the hypochlorites, potassium chlorate, etc.) should not be mixed with easily oxidizable organic substances, for fear of forming explosive compounds. 7. The two principal solvents of the U. S. P. are alcohol and water. Each of these has its own class of easily soluble bodies. These bodies are often pre- cipitated from their solutions in either of these solvents by the addition of the other. Thus the tinctures of iodine, camphor, essential oils, the gums and gum-resins, aloes, etc., are precipitated or rendered unsightly by the addition of water or watery solutions of drugs or chemicals. 8. There are some solutions that should always be prescribed alone, or in a plain watery solution, as they readily decompose. Among these may be mentioned the compound S)rup of hypophosphiles, Fowler's, Donovan's, and Lugol's solutions. These few rules will serve to call the student's attention to the subject, and to the general range of incompatibles. PART VI. PHYSIOLOGICAL AND CLINICAL CHEMISTRY. 854. Origin of Vegetable Energy. — In the consideration of living bodies we are led in the outset to divide them into two distinct classes; plants which grow silently under the action of sunh'ght, and animals which grow also, but manifest their im- pressions and their will by active movements. This difference is not, however, well marked in all cases, as plants are known to exhibit active movements. The difference between plants and animals is more clearly defined by the character of their food, and the chemical pro- cesses which accompany their growth. The vegetable receives its energy principally from the sun's rays, and feeds upon substances from the mineral kingdom, which are destitute of potential energy. With these substances, CO2, N and H^O, it undertakes to build up an organism. In order to do so the absorption of the energy of heat and light is necessary. These it obtains from the sun, or from some artifical source of light and heat which can take its place. By the aid of these, it chemically combines inert bodies into potential organic sub- stances. Animals, on the other hand, decompose and render sensible the potential energy stored up in organic substances prepared by the plant. This energy they convert into kinetic energy (heat, nervous energy, and muscular movement). At the same time, they eject the used up products in the chemically inert form of CO2, H2O and urea, suited for the use of the plant. In a word, the animal lives on the energy stored up by the plant. When an animal respires, it absorbs a quantity of oxygen which varies from 9 to 300 thousandths of its weight in every 24 hours. Almost all of this oxygen is used to produce CO2 and HjO with its combustible matters. This is the prin- cipal source of its energy. Plant cells respire also in the same S°9 SIO MEDICAL CHEMISTRY. way and for the same purpose as animal cells. Plants use up a part of their stored energy in exactly the same manner as do animals, by oxidation. The functions of the protoplasm in plants require the expen- diture of energy, and this energy is produced by oxidation of combustibles. In the plant then, we have two processes going on at the same time ; the taking in of CQj and HjO, and, the construction of complex organic compounds from them, and the burning up of a portion of these compounds to furnish the necessary vital energy to carry on its functions, with the exhala- tion of CO2 and H2O. The balance however, is in favor of the first of these processes, during the daytime, but at night the plant lives like an animal, borrowing its energy from the com- bustion of its reserves. This fact is shown by the increase of temperature of certain plants at night, and of flowers just at the moment of expanding, or in the heat developed by the sprouting of grain, when the only source of energy is the decomposition of reserves. 855. Chlorophyll. — When the green parts of a plant are exposed to air and sunlight, they have the power in some way of absorbing the small amount of CO2 from the air, and returning oxygen to the air. If we examine the plant for the carbon, we find a series of bodies which have been studied under the name of carbohydrates, viz : glucose, laevulose, sucrose, starch, etc. The first of these substances formed, so far as we can learn, are glucose and starch. We also find that certain nitrogenous products are formed. The nitrogen used is usually in the fully saturated or chem- ically inert form ; /. e. ammonia, nitrates and possibly urea and amids or amins found in the soil. It is probable that most of these amid bodies are converted into nitrates before being used by the plant. The mechanism that causes the decomposition of water and carbon dioxide has been proven to be the green coloring matter of the leaves. It can be proven that this coloring matter, or chlorophyll, will produce the change when exhausted from the leaf with alco- hol or petroleum ether. The rapidity of the absorption of COj and evolution of O, is proportional to the intensity of the light. The light from an incandescent electric light, or a strong gas light, will also cause the change. The reaction between CO2 and H^O that takes place, by which PHYSIOLOGICAL AND CLINICAL CHEMISTRY. 51I CO2 disappears and oxygen evolves, would be represented as follows : — CO, + H,0 = O, + C^og I volume. I volume. Formaldehyde, There are reasons for thinking that this reaction does not exactly represent the change that takes place, but that the chlorophyll, under the action of the sun's rays, combines with hydrogen to form a hydride. The hydrogen is obtained by the decomposition of HjO and the liberation of oxygen. This hydride of chlorophyll, or chlorophyllin, gives up its hydrogen to the CO, as follows : — H, + CO, = COH, + O. In either case the first compound formed is formaldehyde, which by polymerizing forms CsHuOe or — H H H H H H O O O O I 0=C-C— C— C— C-C— OH H H H H H It is thus that the plant prepares sugars, starch, and cellulose, by polymerization of the formaldehyde, and then slight changes in the hydration or dehydration of the product. The organic products of plant synthesis can be grouped into the following five classes : — 1. Alcohols, the sugars, and other carbohydrates. 2. The fats. 3. The hydrocarbons. 4. Albuminoid matters. 5. Nitrogenous substances not albuminoid. 856. Assimilation of Nitrogen. — It has been proven by many series of experiments that plants cannot, to any appreciable extent, assimilate free nitrogen from the air. The present state of our knowledge teaches us that plants receive the most of their nitrogen as nitrates and ammonia. By far the largest absorption is as nitrates. These nitrates are pro- duced in the air by electric discharges and the evaporation of saline waters. (See Art. i88.) A considerable production of nitrates takes place in arable soils under the influence of specific organisms which act upon ammonia and nitrogenous matters found in such soils. This organism is known as the nitrifying 512 MEDICAL CHEMISTRY. ferment, and is always present in soils containing vegetable matter. (See Organized Ferments, page 527.) It is probable that plants can absorb urea and some other soluble nitrogenous bodies of. animal origin to a slight degree, but they are quickly transformed in the cells of the roots. As we are not acquainted with the constitution of albuminoids, we cannot follow the reactions for the building up of these bodies in the plant. We do know by experience that plants thrive best on nitrogen in the form of nitrates. That the nitrates enter the circulation and reach the leaves, where they meet with very strong reducing agents in formaldehyde and glucose. This reduction probably takes place as we see it in the warming of alcohol with nitric acid, with the production of hydrocyanic acid, formic acid, and water. This reaction takes place at about 35° to 40° C, /. e., at summer temperature. We may represent the reactibn as it would occur in the leaf as follows : 2HNO5 + sCOHj = 2HCN + 3COj + SH,0 Nitric acid. Formaldehyde. Hydrocyanic acid. The presence of hydrocyanic acid is well known in the al- mond, laurel, rose, peach, and many other leaves, fruits, and flowers. Again it has been shown that hydrocyanic acid, in presence of water and formaldehyde, can form certain amids which have been recognized as among the decomposition products of albu- min. It is probable then that the origin of albuminoid bodies in plants is that here indicated in brief outline, and represented by the following empirical reaction : 66CHjO + 17CNH = CjjHj^NijOjj + 21HCOOH Albumin. Formic acid. The albumin once formed, it can be transformed into other proteids. In a brief way, then, we have traced a few of the syn- thetic reactions by which plants prepare their reserves of poten- tial organic bodies, or bodies that on oxidation in the animal body, when used as food, can give out heat, nervous and mus- cular energy. We have thus the source of the energy of animal life ; for animals subsist upon the products prepared by plants, either directly, or subsist upon animals which in turn feed upon the stores of starch, gum, sugar, and albuminoid bodies laid up by plants. It will be noticed that the edible parts of plants are the PHYSIOLOGICAL AND CLINICAL CHEMISTRY. 513 fruits, tubers or root-stalks in which the plant has stored these reserves intended for the nourishment of the new germ, when needed to start it in its growth. 857. Animal Synthesis. — We have seen that the general result of plant growth is synthetical, while that of the animal is in the main destructive or analytical. In the animal, how- ever, we have synthetic processes, which resemble those of the plant. There are a few animals whose cells possess chlorophyll \Hydra viridis). They behave like plants in sunlight, giving off oxygen and storing up carbon. The formation of fat in the animal body out of albuminoids and carbohydrates is undoubt- edly a synthetic process. Animals find it necessary to store up reserve products, and they first convert a part of the potential energy into kinetic energy, and then reconvert it back into po- tential energy, stored up in the form of adipose tissue. When the food taken furnishes more energy than is required for present needs, the excess is partly stored up in the form of fat, to be liberated for use when the supply is deficient. 858. Proximate Principles. — When animals take food composed of the carbohydrates, fats, and albuminoids, they first get them into a soluble and diffusible form, then absorb them into their circulation. Then there begins a process of assimila- tion or appropriation. The animal foods usually consist largely of albuminoid, fatty, and mineral matters, except in case of milk, which contains all of the classes above mentioned, or it is what has been called a perfect food. Although we take as food various mixtures of vegetable and animal tissues and products, we may divide the proximate principles into carbohydrates (including alco- hols, starch, sugars, and gums), fats, albuminoids or pro- teids, and mineral salts; Each of these has its special uses in the economy, and all of them are necessary to the perfect main- tenance of health. If either of them is lacking in our food, the body can, for a time, overcome the deficiency by transforming the others into a substitute of that which is missing. It is found, • however, that this is always attended with loss of energy and well-being. 859. Origin and R61e of Inorganic Substances in the Human Body. — ^Besides the organic matters of which we have briefly traced the origin, there exist in human tissues certain inorganic or mineral matters, which, from their constant pres- ence, must have an important office to perform. The human body as a whole contains about 70 per cent, of water and 30 per 44 514 MEDICAL CHEMISTRY. cent, of solid matters. The amount of ash left on burning an adult body is from 3 to 5 per cent. There is, therefore, about a fourth of the body made up of dry organic matter. 860, Gaseous Matters. — Oxygen, partly combined and partly in solution, is found in the blood and almost all the liquids of the body. It unites in the blood with the haemo- globin of the red blood- cells, which renders it active and carries it to all the tissues. In this manner it is brought in contact with the oxidizable products of the hydration of proteids, and burns them, and assists all the tissues in disposing of waste products of cell action. An adult absorbs from 770 to 850 grams of oxygen daily, and exhales by the lungs 540 to 720 grams as CO2; a part of the remainder is exhaled by the skin in thesame state, and a part is converted into water, urea, and other oxidation products. The oxygen excreted is about one-fifth more than we inhale ; the excess coming from food taken. Nitrogen is found dissolved in the blood and other fluids, and is contained in all cavities which are filled with gas. In combination it assists very largely in making up the tissues. Carbon Dioxid is met with in expired air, and dissolved in many of the fluids of the body, and in the gases of the intestine. In the blood, saliva, lymph, bile and other fluids it is found in combination as carbonates of the alkaline and earthy metals. In the blood it is also, found combined with the alkal;ne phosphates. One molecule of sodium phosphate, which alka- linizes the blood, combines with 2CO2. This weak compound can be decomposed and the CO.; expelled, by passing through the fluid an inert gas at 37° C. (98.5° F.), or by the presence of oxygen combined with hsemoglobin. It also forms weak combinations with serin and globuhn of the blood. When diluted with water and heated, or when put in a nearly complete vacuum, these compounds part with the carbon dioxid. The CO2 is carried from the tissues to the lungs • in these weak combinations. Hydrogen is found free in the gases of the intestines, where it is formed by fermentation. 861, Water forms about 70 per cent, of an adult human body. The proportion is greater in infants and less in the aged. An adult takes in about 2500 c.c. and excretes about 2600 c.c. daily. The excess of 100 c.c. excreled, above that taken in, comes from the oxidation of the food or tissues. The proportion of water varies considerably in the various tissues and fluids of the PHYSIOLOGICAL AND CLINICAL CHEMISTRY. 5 15 body. The sweat contains 99.5 per cent. ; the lymph 93 to 96 per cent. : chyle 90 to 97 per cent. ; milk 86 to 90 per cent. ; blood 78 per cent., as a mean ; nerves 70 per cent. ; brain 75 per cent. ; muscles 76 per cent. ; cartilage 55 per cent. ; bones 22 to 40 per cent. ; teeth 10 per cent. Water is essential in carrying on the vital processes. It dissolves the substances intended for the nutrition of the tissues, as well as the waste products of their disintegration. It is thus the medium of all chemical reactions taking place within the body, and of the transfer of materials from one place to another. Water is one of the chief agents used by plants in building up the carbohydrates. It is also, in the animal, one of the chief agents used in the digestion, assimilation, and dissimilation of proximate principles of foods. The water of the tissues may be reduced by hemorrhages, diarrhoea and other exhausting dis- charges. The person thus affected usually suffers intense thirst, and water should be supplied freely. It sometimes becomes necessary (hemorrhage, cholera) to supply the water by venous injections of a 0.75 per cent, salt solution. Frogs die when they have lost an amount of water equal to 30 per cent, of their body weight ; but they can live for two days in an atmosphere of pure oxygen, after all their blood has been displaced by a 0.75 per cent, salt solution. (Oertmann.) During this time, they use. the same amount of oxygen and ex- hale the same amount of CO2 as in health. A considerable increase of water in the body is harmful, as it increases tissue waste, dissolves haemoglobin from the red corpuscles, and thus reduces the oxygen-carrying power of the blood, and washes away the soluble saline matters. Injections of a great excess of water into the circulation may cause death. A deficiency of water, if prolonged, leads to the accumu- lation of waste products in the blood and tissues, to deficient nutrition, often leading to constipation, dyspeptic symptoms, loss of weight, and rheumatic or gouty affections. Hydrogen Peroxide has been found in the sweat and a few other fluids of the body. Hydrogen Sulphide is found in the intestine as the result of the decomposition of bile and proteids by bacteria. Ammonia is formed by the same decompositions, but it soon combines with acids to form salts. Acids. Free hydrochloric acid is found in the gastric juice. Lactic Acid occurs in the stomach during digestion, and it is produced in the intestine along with butyric acid by the action Sl6 MEDICAL CHEMISTRY. of special ferments. Sarcolactic Acid is found in the juice of the muscles, during and after active contraction. The acidity of muscle increases for some hours after death. 862. Metallic Salts. — Dissolved in the fluids or combined with the organic substances composing the tissues, are found certain metallic salts, which play an important r61e in nutrition. They give to these organic substances new and special proper- ties, such as solubility, dialysability, the power of solidifying, as in tendons and bones, and the property of elasticity, resist- ance, etc. Iron and copper play a specific role, in the constitu- tion of certain bodies (nuclein, protoplasm haemoglobin, etc.). Sodium Chloride is the most abundant of these saline bodies. We absorb and" eliminate about 14 grams a day. Its principal function is to favor solution and osmosis of the proteid bodies, and it thus facilitates nutrition. It also facilitates the carrying away of the excrementitious matters formed by the activity of the ceils. Common salt is necessary to the function of the various glands of the body. It enters into the composition of cartilage, bone, teeth, etc. A weak solution of this salt in- creases the solubility of most of the proteids. It increases the urinary secretion without increasing the elimination of urea. About 10 to 12 grams of NaCl are excreted daily by the urine, besides that found in the perspiration, tears and faeces. Sodium chloride is more abundant than potassium chloride in the plasma of the fluids, while the latter is more abundant in the cellular elements. Potassiurn chloride cannot take the place of sodium chloride. Potassium Chloride is met with in the cells of every soft tissue, in the intercellular fluids, muscle juice, and nervous tissue. It seems to have a true stimulant action upon the activity of the cells. Plants have need of and contain more potassium than sodium salts. This is probably because the principal work of plants is constructive, which action is stimulated by potassium salts. Sodium chloride rather favors the dissimilation of cell waste. ■ Herbivorous animals require some NaCl to favor a good state of health. The Calcium Salts are furnished by both food and drink. Lime gives solidity to the skeleton, and resistance to the whole body. It is the principal solidifying agent, and when the tissues degenerate it accumulates. In the disease called rickets and osteomalacia it is deficient in the bones, which are soft and easily bent. Magnesium is found in the tissues with lime. Its special PHYSIOLOGICAL AND CLINICAL CHEMISTRY. 517 role is not well understood. It is a constant ingredient in brain matter, muscles, and chlorophyll of plants. The Sulphates are always to be found in the urine and in other fluids. HjSOi is constantly prepared by the disintegrated and oxidized proteids, most of which contain sulphur. About 70 per cent, of the sulphur of proteids appeais as phenol- sulphate, skatoxyl sulphate, or indol-sulphate in the urine. The sulphates of lime and magnesium are abundant in cartilage. We excrete by the urine from 1.5 to 2.5 grams per day of sul- phuric acid combined as sulphates and ethers. They are in- creased by an animal and decreased by a vegetable diet. The Alkaline Carbonates and bicarbonates exist in the lymph, chyle, saliva, bile, blood, etc. These salts of potassium exist in the blood and parotid saliva of herbivorous animals. It is the bicarbonate of sodium that gives most of the alkalinity to the blood and other liquids. With carnivorous animals the alkalinity is due to the phosphates and carbonate combined. These salts are furnished by the food, especially as salts of the organic acids, which by oxidation are converted into carbonates. Both the absorption of oxygen and the oxidation of organic matters are favored by an alkaline medium. The bodies most easily oxidized in alkaline solution are the sugars, alcohols, or^ ganic acids, and then fats ; the last being saponified and the glycerin and acid being oxidized separately. Ammonium Carbonate is met with in traces in the blood. It appears in the blood, stools, and breath at the same time in cholera.' The Alkaline Phosphates are found in almost all tissues of the body. The phosphate of sodium, HNa^POi is the one to which the alkalinity of the blood is largely due. The potassium salt predominates in the blood-cells. The blood of omnivorous and carnivorous animals contains more phosphates than that of the herbivorous. The phosphates are eliminated principally by the urine in the form of neutral or acid phos- phates of sodium, calcium, and magnesium. A little is excreted by the faeces, and a small amount in some other forms. As we take a large part of our phosphates in our food as the- potassium salt, it is probable that the sodium salt is formed by the reaction of NaCl upon K^HPOj in the blood and lymph. From this reaction there results the NajHPOi of the plasma, and KCl of the corpuscles. In all actively growing parts of the body, in red and white blood-corpuscles, in muscles, nerve tissue, yolk of eggs, the Sl8 MEDICAL- CHEMISTRY. seeds and young sprouts of plants, we usually find certain organic bodies, rich in phosphorus, such as lecithin, nuclein, legumin, etc. The Earthy Phosphates are met with in the bones, teeth, and in less amount in certain tissues and in the urine. The Carbonate of Calcium is found to a slight extent in bones and in the shell of moUusks. It sometimes occurs in solution as the bicarbonate, but often in the insoluble state. This salt sometimes gives rise to concretions in the saliva, or upon the teeth, and in the labyrinth of the ear (otoliths). * Silica occurs in small quantity in both plants and animals, but its function has not been clearly made out. It has some well-defined use, and is found very widely distributed in both animals and plants. Iron is found as an essential constituent of certain coloring matters, as haemoglobin, yolk of egg, the pigments of the skin, hair,, eyes, etc. The most remarkable compounds containing it are the haemoglobin of the red blood-corpuscles and nuclein, or the nuclei of the cells throughout the body. One thousand parts of blood of man contain 0.56 part of iron; of beef, 0.51 ; of the goat, 0.33 parts. Most of our food and drink contains traces of iron, and our meats contain enough to satisfy our wants. It is eliminated by the bile and fseces. Iron coiiipound seems to be the principal carrier of oxygen in the blood. We administer it to increase the haemoglobin and the oxidizing power of the blood. In vegetables, it enters into the composition of protoplasm of cells, and possibly in chlorophyll, although this is disputed. Iron seems to be essential to the growth of plants as well as of animals. Copper enters into the composition of some plants and animals. As it always occurs in these organisms, it is safe to say that it has some unknown role to perform. In certain organisms it seems to replace iron. Copper is found to exist in many cereals and food products. Lead, manganese, silver, zinc, and other metals are frequently taken with food or drink, and that they exert some action on the economy is certain, although we are ignorant of their exact function. THE FERMENTS. 863. Very many of the changes that take place in the body are produced through the agency of ferments. Not only do we have to do with those soluble active proteids which produce THE FERMENTS. 519 hydration of other compounds, breaking up complex molecules into simpler ones, but there are a number of such processes due to the action of certain microscopic organized bodies. It will be convenient, therefore, to give here some account of these ferments. They may be divided into two groups, the soluble and the organized ferments. 864. The soluble or unorganized ferments, or enzymes, are a. class of albuminoid bodies which have the power, under favorable circumstances, of causing certain chemical changes in other bodies with which they are brought in contact, without themselves undergoing any change. They are called ferments because of the similarity of their action to that of yeast and other well-known ferments. Some of these bodies are of vegetable, while others are of animal origin. Those of vegetable origin are diastase, emulsin, papain, and myrosin; while those of animal origin are ptyalin (salivary diastase), pepsin, curd- ling ferment, pancreatic diastase, trypsin, invertin, histozym, and probably others. The exact chemical composition of these bodies is unknown, except that they are proteids. They are all soluble in water, are precipitated by alcohol and by lead acetate. They are very diffusible, lose their activity by being boiled with water, but are not precipitated. They have not yet been obtained in a state of absolute purity. The artificial preparations are mixtures of the true ferment with other products found with them in the diges- tive secretions. The soluble ferments are chiefly known under the collective name of enzymes. They are characterized by the fact that a very small quantity of the enzyme is capable of transforming a large amount of the substance acted upon. Their activity is dependent upon the temperature, being absent at very low temperatures, increasing as the temperature is raised to a certain point, which varies slightly in different enzymes, then again diminishing as the temperature is further raised, and at a sufficiently high temperature they lose their activity, the albu- minoid basis being coagulated and precipitated. They are gen- erally sensitive to a change of reaction of the solution in which they are acting, from alkaline to acid, or from acid to alkaline. Certain salts destroy their action, while others only retard it. Their activity is in all cases lessened, and finally stopped, by the presence of an excess of the products which they give rise to. They will stand a higher temperature when dry than when in the moist condition. They may even be heated in the dry state to ioo° C. (212° F.) without permanent loss of their S20 MEDICAL CHEMISTRY. activity. Analysis shows their composition to be more nearly that of the proteids than of any other class of substances. The only means at our disposal for determining the presence of an en;:yme, is that of ascertaining the change it is able to produce in another substance. The soluble ferments have a definite ascertainable limit of energy. Their power is used up in proportion to the work done, and the value of the ferment is generally estimated by deter- mining the amount of food substance which it can convert, under fixed conditions. They are soluble in water, from which they are precipitated by an excess of absolute alcohol. In many cases, they may be precipitated from their aqueous solution by saturation with (NH4)2S04. They are soluble in glycerin, from which they are precipitated by alcohol. They are not diffusible, and may be separated from diffusible substances by dialysis. They are prepared by cell action in certain portions of plants and animals, but in most cases the enzymes do not exist in the free or active condition in the cells, but in the form of an inactive antecedent, to which the name of zymogen is applied It is frequently necessary, therefore, to treat the tissue with some reagent that shall convert the zymogen into an active enzyme, in order to obtain an active extract. The solutions of the enzymes readily undergo fermentation and putrefaction, and lose their activity. It is essential, then, to ensure the preservation of their activity in solutions, that some antiseptic be employed. The most suitable antiseptics for this purpose are chloroform (i in 200), thymol (5 per cent.), salicylic. acid (i per cent.), and alcohol (15 to 25 per cent). In order to distinguish between the soluble enzymes and an organized ferment, it is best to carry on the digestion in the presence of chloroform, which is inert toward an enzyme, but inhibits the growth and activity of organized ferments. Sodium fluoride (i per cent.) entirely checks the growth of the organized, but is without action on the soluble ferments. 865. Diastase, or Maltin, is the ferment formed from the gluten, in the cereal grains, at the time of sprouting. Its chief object is the conversion of starch into dextrin and maltose. Ptyalin of saliva and pancreatic diastase, if not identical with vegetable diastase, act in exactly the same way. They all act upon cooked starch with great rapidity, but have a very slow action upon raw starch. The process is one of hydration, and the action is similar to that which takes place when dilute sulphuric acid is boiled with starch or cellulose. When water is added to H2SO4 THE FERMENTS. 5 21 it probably forms H606S,(H2S04.2H20) or orthosulpliuric acid. This acid, when boiled, tends to part with a portion of its water, and if starch or other easily hydrated compound be present, it imparts this water to that body, in the nascent state, so to speak. Diastase acts upon the starch at ordinary temperatures, in the same way that HsSOe does at a higher temperature. The first effect is to thoroughly liquefy the starch, then convert it into dextrin, and finally the dextrin into maltose. The most probable explanation of how the change is eiiected is, that the enzyme combines with the starch to form a compound which reacts with water, and splits up into two simpler compounds — the one a hydrate of the starch, and the other the original enzyme itself. Kxtracts of Malt, as met with in the market, are infusions of malted barley, sometimes containing dextrin, malt sugar, and dextrose. The bitter non-saccharine "malt extracts," of the market, as a rule, contain little or no diastase, and are simply weak beers. A solid extract is now produced extensively by evaporating an infusion of malt, generally in a vacuum at a low temperature. It should have a light color; the taste should be peculiarly sweet and the odor pleasant. The solution in nine parts of water should be only slightly turbid, and should give an abundant pre- cipitate a few minutes after being mixed with an equal volume of picric acid. The insoluble matter should appear under the mic- roscope as amorphous coagula and hexagonal prisms. The amount of starch that a given weight of diastase can transform is variously stated at from 2000 to 100,000 times its own weight, which, however, seems to be a fixed quantity with any given specimen of diastase. The rapidity of its action seems to depend upon the relative proportions of starch and ferment present. When the ferment is present in large quantity, the action is very fapid, almost instantaneous; while if it is small in proportion to the starch, it is slower in action. Diastasic fer- ment does not exist in the saliva and pancreatic juice of infants, previous to the sixth or seventh month, in sufficient quantity to digest much starch. The digestive power varies greatly in dif- ferent infants. The Diastasic Value of Malt Extracts and Pancreatic Extracts. — The method of determining the diastasic value of malt extracts and of pan- creatic extracts is as follows: A one per cent, solution of starch mucilage is employed. This is prepared by boiling 10 grams of any pure starch in water, ceding, and making up to I liter. Tenc.c. of this standard mucilage is 522 MEDICAL CHEMISTRY. mixed in a beaker with 90 c.c. of water. The mixture is then warmed to about 40° C. (104° F.), and a measured amount of the milt extract or pancreatic extract is added, the exact time of adding it being noted. At short intervals a drop of the mixture is placed upon a plate or white slab with a drop of a dilute aqueous solution of iodine. As long as starch is present in the solution, it will continue to give a blue color. When all the starch is converted into erythro-dextrin, a pink or brown color is produced. When all the efythro- dextrin disappears from the solution no color is produced with iodine. This has been termed the achromic point. This paint should be reached at the end of not less than six minutes, in order that the end reaction mxy be deter- mined with sharpness. When prolonged beyond this time the change is too gradual to be exactly determined. In the statement of the results we employ the following formula : D— _ x ^. in which S = the weight of starch employed ; P, the weight of pancreatic ex- tract or malt extract employed ; T, the observed time from the addition of the malt extract to the achromic point, and 5 the standard time in minutes. If, for example, to c.c. of the starch mucilage was taken and i grm. of a pan- creatic extract was added, and the time required to reach the achromic point was 'I minutes, the above formula would become : — D = — X — = 166.6 c.c. 0.1 3 of the starch mucilage changed to the achromic point by I grm. of the extract in 5 minutes. As the mucilage solution contains i per cent, of dry starch, the 166.6 c.c. of this solution contains 1.666 grms. This method is equally applicable to malt diastase, salivary diastase, or pancreatic diastase. A good dry extract of malt should digest its own weight of starch in twelve minutes. 866. Emulsin or Synaptase occurs in sweet and bitter al- monds. It may be extracted by digesting the almonds, freed from fat by pressure, for several hours, with water. The filtered liquid is acidified with acetic acid, to precipitate cpnglutin, and the emulsin is then thrown down with alcohol, filtered off, washed with alcohol, and dried. It is a white, friable mass, soluble in water, and capable of converting large quantities of amygdalin into sugar, prussic acid, and benzoic aldehyde ; it also converts salicin into sugar and saligenin. Its aqueous solution readily decomposes, yielding lactic acid. Myrosin is the ferment of mustard. 867. Pepsin, contained in gastric juice, is secreted by the glands of the stomach. It may be separated from the other con- stituents of filtered gastric juice by dialysis, as it does not diffuse through membranes. It is readily prepared by digesting the mucous membrane of the pyloric end of the stomach of the pig, first with strong alcohol, and after twenty- four hours expelling the alcohol by pressure, and digesting for some days with glycerin, slightly acidified with hydrochloric acid. Filter through muslin, then through paper, precipitate the pepsin with absolute alcohol, collect on a filter, and dry. Other methods are in use. THE FERMENTS. 523 Pepsin is a yellowish or grayish-white powder, soluble in water and glycerin, but insoluble in alcohol. It gives few of the albu- min reactions, and is precipitated by the acetates of lead. When dry, it may be heated to iio° €.{230° F.) without losing its activity, but its solutions lose it at a much lower temperature. Its activity is greatest at about 40° C. (104° F.), and requires hydrochloric, phosphoric, lactic, or other dilute acid to develop its peculiar action. The presence of o. i per cent, of NaCl favors its action, but more than 0.5 per cent, hinders it. Admixture of bile, carbolic acid, or excess of alcohol retard or entirely prevent its action. Nearly all metallic salts diminish the action of pepsin. Calomel is an exception to this rule, as is also arsenious and arsenic acids. Many of the alkaloidal salts have a retarding effect, but the chlorides have less than the sulphates. Sugar has a retarding action. Sodium salicylate, antipyrin, antifebrin, paraldehyde, and thallin tend to stimulate the action of pepsin. Sodium carbonate quickly destroys it. The acid of gastric juice is mostly hydrochloric during the intervals of digestion, but during digestion several organic acids are set free by the hydrochloric acid from the acetates, malates, tartrates, etc., taken with the food, so that the real work of the digestion is accomplished with the aid of various organic acids instead of hydrochloric alone. The specific action of pepsin is the change of proteids, whether coagulated or not, into peptones. Peptone is scarcely altered by putrefaction. The proteolytic activity of pepsin varies greatly according to the process of manufacture, and the care exercised. The U. S. P. requires that the official pepsin shall digest 3000 times its own weight of freshly coagulated and disintegrated egg albumin in six hours^ when tested by the method given. 868. Valuation of Pepsin. — The digestive value of pepsin is a matter of considerable importance. The method of the U. S. P. requires the following three solutions: — (a) To 294 c.c. of water add 6 c.c. of dilute HCl. .(b) In 100 c.c. of solution a dissolve 0.067 g^m. (i grain) of the pepsin to be tested. (c) To 95 c.c. of solution a, brought to the temperature 40° C. (104° F.), add s c.c. of solution b. ImmeYse and keep a fresh hen's egg for fifteen minutes in boil- ing water. Then remove and place in cold water. When col^ separate the white coagulated albumin, and rub through a clean sieve having 30 meshes to the linear inch, rejecting the first por- tion passing through. Weigh off 10 grms. of the second clean 524 MEDICAL CHEMISTRY. portion, place in a flask of about 200 c.c. capacity, and add J^ of solution c, and bhake, to distribute the albumin evenly through the liquid. Then add the other half of solution c. Place the flask on a water bath and keep the temperature at about 40° C. (104° F.) for six hours, shaking gently every 15 minutes. The albumin should have disappeared at the expira- tion of this time, leaving at most only a few, thin, insoluble flakes. The relative proteolytic power of pepsin stronger or weaker than that described above, may be determined by ascer- taining how much of solution b made up to 100 c.c. with solu- tion a will be required to exactly dissolve 10 grms. of coagulated and disintegrated albumin under the conditions given above. The above method is somewhat cumbersome and tedious. A better method is the following: Prepare two solutions : — No. I. — To 25 grms. of the well-mixed -nhites of several eggs add enougli distilled water to make exactly 250 c. c. Mix well and boil the solution for 5 minutes. After cooling, make up the solution lo the original volume with water. This solution contains 10 per cent, of egg white, or about 1.22 grms. of dry albumin in 100 c. c. No. 2. — I grm. of the pepsin to be tested is dissolved in 25 c. u. of water, 2 c.c. of dilute HCl (U. S. P.) is added, and enough water to make the solution up to 50 c. c. Procedure. — Measure out into a beaker or bottle 50 c.c. of the albumin solution and warm on a water bath to about 40° C. (104° F. ). Add to this 2 c.c. of dilute HCl (U. S. P.), and from 0.5 to 5 c.c, of the pepsin solution. The more active the pepsin, the less the quantity lo be taken. It will some- times be necessary, with an unknown pepsin, to make a preliminary test to determine the approximate time required by the digestion, as it is best to so regulate the quantity of pepsin and albumin, that the digestion should be complete in a little less than 2 hours. The time when the pepsin is added must be carefully noted, artel the temperature kept at about 35 to 40° C. {95 lo 104° F.). At intervals of 10 minutes draw out a few drops of the solution with an ordinary dropper pipette, and float it upon a few drops of pure HNO, in a narrow lest tube. Note the time when the HNO3 ceases to give a coagu- lum of albumin, or when the albumin disappears. We thus get for the cal- culation, the weight of the egg albumin, A ; the weight of the pepsin taken, P ; and the time consumed, T. We next assume the standard time of 3 hours, the average time of stomach digestion. The relation between the quantities of albumin and pepsin is expressed by the fraction p-, i. ?., it is found by di- viding the amount of albumin by the weight of the pepsin. This result gives the amount of albumin digested by one part of pepsin in the time observed in the experiment. To calculate what this would digest in the standard time, yffi must multiply the above ratio by the ratio of the observed time to the standard time, or, to put this in the form of an algebraic equation, we have, D (or digestive power) = -= X J- Suppose 50 c.c. of solution No. i, containing 5 grms. of egg white be taken. THE FERMENTS. 525 and that I c.c. of solulion 2 be taken, containing .02 grm. of pepsin, and that the time required for the digestion was two hours. If we subslitute these quantities in the above equation we have D = .^'^ X f = -ii = 375 grms. ; i. e., I grm. of this pepsin is capable of digesting 375 grms. of egg albumin in 3 hours, or 750 grms. in 6 hours. As egg white contains about 12.2 per cent, of dry albunjin, i grm. of this pepsin will digest 45.7 grms of dry albumin in 3 hours. Tnis method gives an exact statement of results; requires little if any skill in manipulation, requires no shaking, and the results are uniform. 869. Trypsin occurs in the pancreatic juice, and may be extracted from the pancreas by a process similar to that described above for pepsin, except that no acid is used. Thus prepared, pancreatin is a yellowish-white amorphous powder, soluble in water and glycerin, but precipitated by alcohol. It possesses the property of acting upon the proteids in a way somewhat similar to pepsin, but is active only in alkaline solutions. The pan- creatic juice contains a ferment called steapsin or pialyn, which is not soluble in glycerin and is destroyed by acids and alcohol. It emulsifies and partially saponifies the fats. A part of the peptone at first formed by the pancreatic juice, is afterward converted into tyrosin and leucin. The digestion of the proteids is thus begun in the stomach, in an acid medium, and finished in the small intestine, in an alkaline medium. There is this difference in the two processes, that while acid pepsin readily liquefies the proteid bodies, it does not com- pletely conve'rt them into peptones; this completion of the pro- cess is more quickly and completely done by the trypsin (see under Albumoses). The secretion of Peyer's glands converts dextrin and maltose into glucose, but does not affect starch. The diastase of pancreatic juice, also called amylopsin, is identical in its action with ptyalin of the saliva, and malt dias- tase, already described. Like these, it converts starch into maltose, but it acts better in presence of bile than when alone. The method of determining the diastasic value of pancreatic extracts is the same as that described above for malt extracts. 870. Rennin, or milk-curdling ferment, is found in, the ex- tract of the pancreas. It is not so abundant in this gland, how- ever, as in aqueous and glycerin extracts of the mucous mem- brane of the stomach. Nothing is known of the chemical nature of rennin. Under the name of rennet, it has been employed for centuries to coagulate the casein of milk in the manufacture of cheese. For this purpose it is usually prepared from the stomach of the 526 MEDICAL CHEMISTRY. calf, where it exists, in the form of rennin zymogen, which is converted by standing or by weak acids into rennin. It occurs in the stomachs of both children and adults. It has been found in pmall quantities in normal urine. 871. Fibrin-ferment.— The coagulation of paraglobulin in the formation of blood clot, is now believed to be caused by a special ferment. It may be prepared by mixing blood serum with 10 to 15 vol- umes of strong alcohol, allow to stand 14 days, and filter. The precipitate contains coagulated proteids with the ferment adher- ing to them. The ferment may be dissolved out by water. The blood in circulation does not contain the feVment, but it is formed by some change after the blood is drawn from the vessels; probably by the disintegration of the white corpuscles and the third corpuscle, or blood tablets. It seems to be a globulin-like body. There are other globulins which have a similar action in the formation of fibrin, as this ferment. The myosin of muscle juice is especially to be men- tioned as one of them. This is sometimes described as muscle enzyme. 872. Invertin is a ferment existing in the intestinal juice, which has the power of inverting cane sugar; /. e., it converts it into dextrose and laevulose. Of its composition and other prop- erties little is known. Invertin, or a substance possessing the same property, as well as a diastatic ferment, is found in the liquid portion of bakers' or brewers' yeast, after the cells have been killed by alcohol. While alive, the cells do not impart the invertin to the solution. It does not affect lactose, maltose, starch, or gums. 873. Histozym is a soluble ferment, supposed to exist in the blood, liver, and kidneys, and which has the power of causing a variety of reactions within the body, such as the conversion of benzoic into hippuric acid, etc. Some authors have described certain other ferments under the name of microzimas, which act as active chemical and physio- logical agents in the body during life, and cause its decom- position after death. They appear as minute molecular gran- ules, and are regarded as a part of the living organism by some, and as distinct organized ferments by others. As these molecular granules do not seem to undergo reproduction, and are not destroyed by antiseptics, it seems unlikely that they are organized structures. 874. Papain is a ferment prepared from the milky juice of ORGANIZED FERMENTS. 527 the paw-paw tree. It is a white, amorphous, granular powder. It is soluble in water and glycerin. This ferment peptonizes proteids very rapidly, the end product being leucin. It acts like trypsin. It has'been used to digest the membrane of croup and diphtheria. Hydrochloric acid lessens its action, as does carbolic acid, but they do not arrest it. It can act in an alka- line neutral or feebly acid solution. Under the name of papoid it is found in the market as a remarkably active digestive agent. It resembles in its action the trypsin of pancreatic fluid. ORGANIZED FERMENTS. 875. Somewhat similar in action to the preceding group of ferments, are certain forms of low vegetable organisms, which are known as organized ferments. These organisms vegetate most readily at temperatures of from 20° C. (68° F.) to about 40° C. (104° F.). Temperatures above or belovi^ these limits retard their growth, while a temperature near the boiling point entirely destroys their activity. A very minute quantity of any of these ferments can grow and exert its peculiar action, as long as its peculiar nourishment lasts, and proper conditions of its life are maintained. Organized ferments excite chemical changes, as the direct physiological result of their growth. They are all killed by hydrogen peroxide, and the chemical change is stopped by it. All physiological fermentations in the organism are caused by the soluble ferments, while pathological fermentations are caused by the organized ferments. The antiseptic agents, as a rule, antifermentatives, check the growth and in many cases kill the organized ferments. (See Art. igi.) The changes produced by the enzymes may be distinguished from those pro- duced by organized ferments by the addition of chloroform or sodium fluoride' (i percent.), both of which check the growth of organized ferments, while the action of enzymes is not inter- fered with. The most important of the ferments of this class are yeast, or alcoholic ferment, acetic acid ferment, lactic, butyric, and putre- factive ferments. With the exception of the first of these organ- isms, they all belong to the bacteria family. Yeast (Torula, or Saccharomyces cerevisiae) consists of one-celled, globular or oval-shaped microscopic plants, multi- plying by budding. There are several varieties of this fungus. The principal action caused by yeast in saccharine fluids is, first, 528 MEDICAL CHEMISTRY. to convert the saccharose into invert sugar, and then change this into alcohol, carbon dioxide, and a trace of succinic acid and glycerin. The spores of yeast are always to be found either in •the air, or upon the surface of fruit, whencfe they find their v^ay into the solutions made from their juices, which explains the apparent spontaneous fermentation. Invertin accompanies the growth of yeast. It has the power of inverting cane sugar. (See Art. 872.) Acetic Acid Ferment (Mycoderma Aceti; occurs usually in the form of chains of very small globular bodies, formed by multiplication of the cells by divisions, at right angles to the line of growth. It belongs to the bacteria family. It grows in alcoholic solutions containing a small amount of albuminous matter or ammoniacal salts, and alkaline and earthy phosphates. A little acetic acid favors its growth, as well as a free supply of air. It acts by causing an oxidation of the alcohol to acetic acid j when this change is complete, the ferment dies for want of nourishment. Saccharomycetes Albicans (Oidium Albicans) is the ferment which is found growing upon the mucous membrane of the mouth of infants, producing the disease known as " thrush " or "sprue." The fungus appears as white patches upon the tongue and other parts of the mouth. The cells are globular, oval, or cylindrical, and occur in colonies or rows. It excites alcoholic fermentation but feebly. Lactic and butyric fermentations go hand in hand, the first usually, if not always, preceding the latter. They thrive best in a neutral or alkaline medium, and grow best without oxygen, at a temperature of 35° C. to 40° C. (95° F, to 104° F.). These conditions exist in the intestines, and they are always found there. The substances most prone to these fermenta- tions are sugars, organic acids, soluble proteids, and especially mucus. The products of the fermentation are lattic, acetic, and butyric acids, carbon dioxide, and free hydrogen. These gases distend the bowel and often produce colic. Any excessive pro- duction of mucus in the bowel, greatly favors these fermentations. The growth of the Bacillus butylicus furnishes a ferment which has the power of inverting cane sugar and slowly pepton- izing albuminoids, but it does not hydrolize either lactose or starch. Urea-ferment. — When urine is exposed to the air its acidity at first increases, and then diminishes rapidly, and gives way to an alkaline reaction. The solution is then found to contain ORGANIZED FERMENTi. 529 ammonium carbonate, formed from the urea. This is due to a hydrolytic change resulting from the growth pf certain micro- organisms, of which the best known is the torula urese. Recent investigations seem to prove that tliCbC organisms are not the only agency that brings about this change, but that there is probably a soluble enzyme that assists or may even perform the conversion without the presence of the organisms. It is quite certain that the mucus secreted in catarrh of the bladder can produce the change, as it takes place in the presence of chloroform and of sodium fluoride. If a urine which is full of torula be filtered through a filter that allows no organisms to pass, the change is stopped. If it be treated with alcohol before filtering, the filtrate has the power of producing the change. It thus seems that the alcohol extracts an enzynje from the torula, while water does not. The most prolific source of this enzyme is the mucus of cystitis. Putrefactive Fermentation is caused by the growth of various forms of bacteria. The proteids are most liable to putrid fermentation. This fermentation takes place in all organic in- fusions containing proteid matters, when exposed to the air ; it also occurs in the small intestine in cases of constipation, or in some forms of indigestion, and to a slight extent in the normal cond4tion. The putrefactive ferments are classified into aerobic (those requiring oxygen), and anaerobic. The first give a little gas, little or no ammonia, and odorous products. The second class decompose the albuminoid matters, producing at first hydrogen, and a little carbonic, acetic, lactic, and butyric acids. Then the matter becomes strongly alkaline from the production of ammonia, with escape of nitrogen, ammonia, hydric sulphide, and complex phosphorous compounds. At the end of some days the mass gives off almost pure CO^ and NH3, and there goes into solution a series of amins and amids among which are amido-stearic acid, leucin, tyrosin, caproic, butyric, and palmitic acids. The two last predominate. At the same time phenol, skatol, indol, pyrrol, and phenylacetic, phenyl- propionic, oxyphenyl propionic, skatol-carbonic, and skatol- acetic acids make their appearance. Finally, more or less poi- sonous toxalbumins, peptone, and ptomaines appear. These products do not all appear in all cases, but are modified by the substance acted upon, and other conditions. Nitrifying Ferment. — This ferment consists of certain microorganisms found in all soils containing organic matter, 45 53° MEDICAL CHEMISTRY. and found especially abundant about the rootlets of plants. They are also found in surface waters. Their function is to convert albuminoid matters and ammonia into nitrous and nitric acids. They therefore act as oxidizing agents, similar to the acetic ferment. It is by this agency that polluted waters dispose of their nitrogenous organic matter, and purify themselves. When a water has thus purified itself, the nitrogen will be found in the form of nitrates, or nitrites of the metals. (See Water Analysis.) It is by the aid of these organisms that plants are able to feed upon albuminoid matters in the soil, and it is claimed that they can fix the free nitrogen of the air, and make a plant food of it. Disease-Producing Organisms. — The organisms of the contagious and infectious diseases belong in this class of organ- ized ferments. They are believed to owe their peculiar action on the body to the peculiar toxalbumin which they produce while multiplying in the fluids. In many cases it has been proven that the toxalbumins which the microbes secrete, and which are pre;- cipitable with alcohol, are the active agents. When injected into the circulation they produce, with or without fever, a state of resistance to the growth, of the microbe, or its effects,. called immunity. NUTRITION, 876. As has already been stated, animals derive their nourish- ment from the vegetable kingdom, either directly, or they live upon animals who, in turn, live upon a vegetable diet. Foods are substances which are required for the nutrition of the body. It has been calculated that the average adult man loses about 1000 grms. of matter daily, in the expired air, sweat, urine, faeces, and other excretions. Food is necessary to replace this waste, if the body-weight is to remain constant. Nutrition takes place in five different phases, viz.: digestion, absorption, assimilation, destructive metabolism, and elimina- tion of waste or excretion. Digestion is the process of con- verting food into dialyzable compounds. Digestion is followed by absorption, that is, the passage of the products of digestion through the walls of the alimentary canal into the blood and lymph, which carty the absorbed material to the tissues. The tissues take up the digested and absorbed material for the nutri- tion of their cells. This is called assimilation. In some FOODS AND DIET. 531 cases assimilation is delayed by the storing up of materials for future use, such as the storing of glycogen in the liver and of fat in the connective tissue. Destructive metabolism is the process continually going on in the tissues, by which they are disintegrated during the physiological activity of the cells. It is chiefly a process of oxidation, the oxygen being supplied by the respiration, and the energy of this oxidation is used up in the physiological activity of the tissues and the production of heat. By this process stored energy is converted into muscular or nerve energy. The elimination of waste products is the discharge from the system of the products of the destructive metabolism. These waste products are no longer required in the system, as their energy has been used up. FOODS AND DIET. 877. Foods are mixtures of various inorganic and organic materials, which are usually termed by the physiologists proxi- mate principles. The chief proximate principles of food are the same as the chief proximate principles of the body. They may be classified as follows : Water, metallic salts, proteids, gelatinoids, fats, carbohydrates, and a few other less important organic constituents. These proximate principles do not occur in natural foods in the pure state, but are mixed in varying pro- portions in the different foods. It is necessary, in a suitable diet for man, that all these above-mentioned proximate princi- ples should exist ; and hence we find them mixed for use in natural foods. In milk and eggs, for example, which form the exclusive food stuff for young animals, we find all the proximate principles mixed in suitable proportions ; hence, they are fre- quently spoken of as perfect foods. Eggs, although a perfect food for birds, are not quite perfect for mammals, as they contain too little carbohydrates. In vegetable foods, as a rule, the carbohydrates predominate, and are, therefore, necessarily mixed with fat and nitrogenous substances in the form of animal food. 878. Diet. — A healthy and suitable diet must possess the following characteristics : i. It must contain the proper amount and proportions of the various proximate principles; that is, of proteids, fats, carbohydrates, salts, and water. 2. It must be adapted to the age, sex, climate, and habits of the individual. 3. It must not only contain the proper proximate principles, 53-2 MEDICAL CHEMISTRY. but they must be in a digestible form. 4. The object of food being to nourish the tissues and repair the loss due to destructive inelambrphosis, the relation between food, exercise, and excretion must, therefore, be properly regulated. In the consideration of diet, it is usual to consider chiefly the three proximate principles, carbohydrates, proteids, and fats. It is necessary that these thiee ingredients should be adjusted so that neither should be in great excess over and above the needs of the body. The proportion of carbon to nitrogen in proteids is about as 15 to 53, or i to 3.5. If a person live entirely on proteid food, his diet will contain too much nitrogen and too little carbon. If he live entirely upon carbohydrates, he would not get sufficient nitrogen to nourish the tissues. The fats and carbohydrates taken together are sometimes called the non-nitro- genous foods. In carbohydrates the H and O exist in the pro- portion to form water. We may regard the H, therefore, as completely burned in his body, and not available for combus- tion or the generation of energy, the carbon alone being avail- able for that purpose. Fats contain much less O in proportion to their carbon and H than do the carbohydrates; they, there- fore, generate more heat in their complete oxidation than the latter. It is found that animals thrive best on diets which supply them with the bulk of their carbon from both fats and carbohydrates. The diet which man constructed for himself, long before theories explained why he did so, contained both carbohydrates and fats. Again, the foods which nature has provided for growing animals, in the shape of milk and eggs, contain fat, the carbohydrates and proteids. From this it would be inferred, that all three of these constituents are essential for the proper nourishment and growth of animals. 879. Diet Tables. — The proper construction of the diet for man has been made the subject of a great deal of investigation, and is a matter of considerable importance. Theattempt has been made in various ways to determine the necessary daily diet of a man under different conditions. Moleschott fixes the fol- lowing daily diet for a man performing a moderate amount of work : — PqPJ, NlTROGHN CaKBON IN Gkms. in Grms. 1 20 grms. ( 4.23 oz.) proteid, containing . . i8.88 64.18 90 " ( 3.17 oz.) fat, " . . . o. 70.20 3.30 " ' (11.64 oz.) carbohydrates, containing o. 146.82 Total, 18.88 2S1.20 FOODS AND DIET. 533 Ranke, by experiments upon himself, determined upon the following as the necessary daily diet : — NiTROGRN Carbon IN Gkms, in Gkms. 100 grms. proteids, containing 15.5 53 " "fat, " o. 79 250 " carbohydrales, containing . . . . o. 93 Total 15.5 225 Dr. E. Smith gives as a fairly sustaining, or famine diet : — Cabbon. Nitrogen, For an adult man 43°° gfs. 200 grs. " " " woman, ; . 3900 " iSo "■ The average adult requires 4100 *' 192 '* An adult in idleness requires of nitrogenous food 2.67 oz., and of carbonaceous food 19.61 oz., which equals 3816 " iSo " For short ordinary labor, 4.56 oz. nitrogenous, 29.24 oz. carbonaceous, which equals . . 5688 " 307 " Active labor, 5.81 oz. nitrogenous food, 34.97 oz. carbonaceous food, or .... 6823 " 391 " Playfair, Ranke, Beigel, Vogel, and others give the daily aver- age of N for average labor as 252 grs., and at rest 171 grs. The following table gives the amount of food which will con- tain the average daily needs of the' human body, according to Moleschott's estimates : — Weight of Food which Contains Food. 120 grms. of proLeid. 420 grms. of non-proteid (go of fat, 330 of carbohydrates). Cheese 350 grms. 1530 grms. l-entils 453 " (>93 " Feas, 537 " 7"4 " Beef 566 " 1945 " Hens' eggs 893 " 776 " Wheat bread, . . . 1332 " 543 " Maize, 1515 " 643 " Potatoes, 6000 " 1 75 1 " The following table gives the results arrived at by different investigators, as to the necessary daily amounts of the three proximate principles demanded by adults in different conditions, with the calories generated by these quantities. To convert this last column into the equivalent in work it is only necessary 534 MEDICAL CHEMISTRY. to multiply the number of calories by 3077 to reduce it to foot- pounds, or by 1.539 ^'^ g^' foot-tons: — Soldier in peace, . . . " light service, . " in the field, . Laborer, " in idleness, . . Carpenter (40 years), Young physician, , . . Laborer, servant, . . . English smith, .... " prize-fighter, . . Wood-chopper (Bavarian Laborer (Silesian), . . Seamstress (London), . Soldier in peace, . . . " war, .... Average population (Paris), Albu- min. 119 117 146 130 137 131 127 134 133 176 288 135 80 54 130 146 "S Fat. 40 35 44 40 72 68 89 102 95 71 88 208 16 29 40 59 48 Carbo- hyd'te. 529 447 504 55° 352 494 362 292 422 666 93 876 552 292 551 557 333 Calor- ies. 2784 2424 2852 2903 2458 2835 2602 2476 2902 3780 2189 5589 2518 1688 2900 3250 2219 Author. Plavfair. Hildesheim. Moleschott. Pettenkofer & Voit. Forster. Playfair. Liebig. Meinert. Playfair. Hammersten. It Gautier. Taking the average of the figures in the last column, and rejecting those which are exceptionally high or low, we find that there are seven that average about 2800 calories. The average for light work or no work is 2400 calories. The following amounts of common foods contain the daily supply for an adult doing ordinary labor : — Ounces. 1. Bread, 18 2. Butter, I 3. Milk 4 4. Bacon, ..*'.. 2 5. Potatoes, 8 6. Cabbage 6 7. Cheese 3^ 8. Sugar s}4 9. Salt ^ 10. Water, alone and in tea, coffee, beer, . . 66)^^ 880, Dynamic Energy of Foods. — Heat and muscular power, or dynamic energy, is one of the important offices of all food. The general result of the chemical changes going on in the Altogether these quantities will contain about I lb. 5^ ozs. of dry substance, though they weigh in all 6 lbs. 14^ ozs. FOODS AND DIET. 535 body, sometimes termed metabolism, is chiefly an oxidation process. The oxidation of organic matter always develops more or less heat energy. Heat and muscular power are con- vertible in the body, and articles that produce heat produce also muscular energy. Energy is usually reckoned eilher in terms of work done, or as its equivalents in heat units. Ttie unit of work is the foot-pound or foot-ton in Englisli measure, or the gram-meter or kilogram-meter in the metric system. The heat unit, or calorie, is the amount of heat necessary to raise the temperature of one kilogram of water from zero to 1° C. In English measures a thermal unit is the amount of heat necessary to raise I pound of water from o to 1° C* A thermal unit ^= .45 calorie. A calorie , = 2.2 thermal units. A thermal unit = 1390 foot-pounds or 0.695 foot-ton. A calorie = 425.5 kilogram-meters, or 425,500 gram-meters. A calorie = 3077.6 foot-pounds. I Kilogram-meter = 7.233 foot-pounds. I Foot-pound = 0.138 kilogram-meter. The heat of combustion is the same, whether the food be burnt in the air or in the human body. The apparatus which is em- ployed for determining the heat of combustion of bodies, consists of a vessel surrounded by a known weight of water, and in which the substance is burned with oxygen. The heat is communicated to the surrounding water, and the rise of temperature of the water is carefully measured with a thermometer. It is called a calori- meter. By means of the calorimeter we are able to determine the amount of heat produced by the combustion of the food or food constituents. The following are some of the results obtained in this way : — XT „ D Pounds of Water Pounds Raised i Ft. Name of Princifle. j^^,^^^ ,0 p. High (Foot Lbs.). 10 grs. glucose, 8.42 6500 10 grs. milk sugar 8.63 6651 10 grs. lump sugar, 8.61 6647 10 grs. arrowroot 10 6 7766 10 grs. butter, 18.60 14,421 10 grs. beef fat, 20.91 16,142 These numbers were obtained with the respective foods in the * A thermal unit is sometimes taken as the heat necessary to raise one pound of water 1° F. A smaller calorie is sometimes used, which is the heat required to raise i grm. of water l° C. 536 MEDICAL CHEMISTRY. natural state. When absolutely dry, fat is found to give 2.5 tin:ies as much heat as starch or sugar. One gram of the following proximate principles, when burned, gives the following amounts of heat and work: — Calories. Foot-tons. Kilogkam-meters. Proteid, 42 6.4 1787 Fat 9-3 '4-2 3957 Carbohydrate, 4-' 6-3 '744 Dr. Rubner obtained, by comparative feeding experiments upon animals, and with the calorimeter, the following figures. Taking the thermotic value of fat at 100, he found that to give the same amount of heat it required : — By Feeding Experiments. By Calorimeter Myosin 225 parts. 213 parts. Lean meat 243 " 235 " Starch, 232 " 229 " Cane sugar, 234 " 235 " Grape sugar 256 " 255 " That is, I gram of fat gives the same amount of heat as 2.25 grams of myosin, or as 2.56 of grape sugar. From these or similar experiments, it is possible to arrive at a definite estima- tion of the potential energy produced by foods. It has been found that the heat value of proteids, when completely burned, is equal to that of carbohydrates, and is, therefore, a little less than one-half the value of fat, as heat-producing agents. It must be remembered, however, that there is this difference : that lean meat has for one of its chief offices the building up of tissue and repairing waste. We do not, therefore, obtain all the possible heat and muscular power from it, as we do from the carbo- hydrates and fats. About one-third of its heating power remains in the urea which is formed from it. In accurate experiments in feeding the human body, it has been found that the proteids, fats, and carbohydrates replace one another in almost the exact proportion of their heats of combustion, when the person ex- perimented with is in a state of idleness. The following table, arranged by Frankland, gives the force produced by i gram of the common articles of food : — FOODS AND DIET. 537 Percentage OF Water. Force-producing Value. Food. ^ In Calories In Kilogram- meters. When Burnt in Oxygen. When Burnt in the Body. Cod-liver oil, Beef fat, Butter, ... Cheshire cheese. Oatmeal Flour,. . Pease-meal, . . . Arrow-root, . ... Ground rice, . . . . Yolk of egg. Cane sugar, Hard-boiled egg, . . . Bread crumb, .... Mackerel, Lean beef, Potatoes, . .... Whiting . White of egg, Milk, .... Apples Cabbage, 24.0 47-° " ' 62.3 ■ ■ 44.0 70-S 70-5 73-0 80.0 86.3 87.0 82.0 88.5 9.107 9.069 7.264 4-647 4.004 3936 3936 3-912 3-813 3-4^ 3-348 2.383 2.231 1.789 1.567 1. 01 3 0.904 0.671 0.662 0.660 0.434 3857 3841 3077 1969 1696 1669 1667 1657 161S 1449 1418 1009 94S 758 664 429 383 284 280 280 184 3857 384' 3077 1846 1665 1627 1598 1657 1591 1400 I418 966 910 683 604 422 32s 244 266 273 178 It is therefore possible to calculate from the analysis of a given food, the energy that we may obtain from it on the assumption that it is well digested. We have but to multiply the amount of each proximate principle, in 'grams, by the figures given above to obtain the heat value in foot-tons, or kilogram-meters. The sum of these several amounts for idleness, according to various investigators, as given above, should be 2400 calories, 1,020,000 kilogram-meters, or 3670 foot-tons. For ordinary work they should be 2800 calories, 1,200,000 kilogram- meters, or 4280 foot-tons, or 8,562,400 foot-pounds. It must not be supposed that all the work represented by these figures can be produced by a man by using the above diets. A considerable part of the energy of the food is used up by the work of the heart and lungs, and necessary muscular move- ments, and a part is lost by radiation of heat from the surface '46 538 MEDICAL CHEMISTRY. of the body, and a part is lost with the breath, perspiration, urine, and faeces. McKendrick puts the amount of work done by a laborer in 8 hours as 125,000 kilogram-meters, or 904,125 foot-pounds. The average daily amount of work performed by laborers is about I million foot-pounds. About one-half as much can be accounted for in other work, leaving about four-fifths of the energy of the food taken, as loss. The best steam engine can utilize about ^ of the total energy of the fuel, while the human body gives about \ of the total energy of its fuel in the form of muscular power. It has been estimated by Prof. Gohren that the horse may transform about 32 per cent, of his food into energy, an ox 43 per cent., a man 53 per cent. These results are higher than those of most other observers. The experiments by Rubner on dogs, show that they use the fuel with great economy as long as it is not given in excess over the needs of the body. If, however, more food was given than their bodies required, they stored up a part of the excess as fat for a time, but finally reached the point where the excess was all wasted : /'. e., there seemed to be a limit to their storing up of fat, and after that the excess taken was thrown away. COMPOSITION OF COMMON FOODS. {Gautier.) Name of Food. 151 ig' M < ( Ratio of 1:2:3 Flesh without Bones : — Beef, fat, " medium fat, . . . " salted, . . . . Veal, Horse-flesh, Smoked bam Fork, salted and smoked, Flesh with Bones : — Beef, fat, . . . " medium fat, " slightly salted, " corned, . . Mutton, very fat, . " medium fat Pork, fresh, fat, " salt, fat, . 183 196 190 218 190 318 255 100 156 167 •75 190 135 160 100 120 166 98 120 115 80 65 36s 660 141 83 93 100 332 160 460 540 II 18 18 117 «3 125 100 40 9 IS 85 100 8 10 5 60 640 688 672 550 717 492 280 130 544 58s 480 430 437 520 365 200 150 150 167 180 88 150 70 80 •9 •5 ■63 •S3 .12 .20 1-43 6.60 .90 ■49 •S3 •S3 2.46 I. 4.60 4.50 FOODS AND DIET. 539 COMPOSITION OF COMMON FOODS.— Continued. Name of Food. Flesh with Bones: — Ham, smoked, Eggs, white, " yolk, . Milk, cow, . " human. Fish in General, . . Eel, of rivers (entire) Salmon (entire), . . Sole, " . . Perch, " . . Cod (fresh), entire, . Herring (salted), . . Salmon " . . Cod (dried), . . Vegetable Foods : — Wheat bread (fresh). Rye " " Wheat, Rye Winter Barley, . . Oats Corn, . . Rice Peas, French beans, . . Kidney " . Lentils Potatoes, . . Cauliflower, . ... Apples, Grapes, ... Almonds, Cocoa, Prepared Foods: — Bouillon, Butter, Lard, Swiss cheese, . . Parmesan cheese, . . Extract of Beef (Liebig's Wine (red Bordeaux), Porter, Beer (ordinary), . " (light), ■ . •s 7, • (a < t 20O 103 160 36 '9 135 89 121 MS 100 86 140 200 532 77 146 90 134 119 128 64 225 225 220 26s IS s 5 7 242 140 6 7 3 33S 441 304 7 S 7 300 7 307 40 4S 4S 220 67 14 2 I Z40 108 4 10 10 12 20 28 SS 70 4-3 20 20 IS 25 2 537 480 850 990 250 159 55° 480 679 675 636 615 599 781 575 540 575 580 200 20 20 80 72 180 70 8 13 4 l.l 15 6 10 II 8 132 io6 17 16 16 19 45 30 II 6.1 23 24 25 16 10 5 29 50 3 15 57 175 4 3 2 340 875 520 86s 877 740 352 469 580 440 455 280 460 257 330 400 140 166 130 140 177 144 145 160 130 "5 760 920 820 54 55 985 119 7 346 275 217 830 871 916 90 333 333 250 450 450 340 100 5 17 66 95 Ratio of 1:2:3 1.50 .07 I 92 I. II 2-37 0-33 2.47 0.56 0.09 0.02 0.0 r I. 0.54 o.oi 0.1 1 0.14 0.082 0.22 0.21 0.46 0.54 0.06 0.09 0.09 0.07 0.09 0.09 2.22 3-43 1. 21 3-3° 0-75 0.36 o .07 1-53 2.52 6.25 6.25 4.68 7.50 4-74 5-17 4.69 11.90 2-55 2.43 2.61 2.19 10.30 4.00 16.00 0.30 1.29 9-57 IS 6.85 S40 MEDICAL CHEMISTRY. 88i. The Digestibility of Foods. — A knowledge of the di- gestibility of foods is of great importance. We live, not upon the food we eat, but upon what we digest and absorb. The following table gives the per cent, of the various foods usually digested by man : — Food Materials. Per. Cent. Digested. Proteid. Fat. Carbohydrate. Meats and fish, Eggs Milk Butter, Oleomargarine, . Wheat bread, ... Corn meal Rice Peas Potatoes, Beets Practically all. 88 to ICO 8l to loo 89 84 86 74 72 79 to 92 96 93 to 98 98 96 99 97 99 96 92 82 It will be noticed in this table that the proteids of milk are less completely digested than those of meats. Children, how- ever, do better than adults in digesting the proteids of milk. We must, of course, in considering this question, neglect the idiosyncrasies of various people. What is digested by one, is often difficult to digest by another. Diseases of the digestive canal frequently interfere with the digestion of food. Such variations from the normal cannot be taken into account in con- sidering the digestibility of foods. In the table on pages 538 and 539 will be found the proximate composition of the ordinary articles of diet. 882. Circumstances that Affect the Digestibility of Foods — Source. — The proteids of animal origin are more easily and completely digested than those from the vegetable kingdom. The same may be said of fats. We know in regard to the carbo- hydrates that the starch from one plant is often more digestible than that from another. We know of no explanation for this. With regard to meat, some kinds of flesh are more easily di- gested than others by artificial gastric juice ; thus, fish is more difficult to digest than meat ; white flesh is more digestible than dark, raw beef than smoked. FOODS AND DIET. 54I Observations made in cases of gastric fistula, upon the time food stayed in thfe stomach, have shown that meat remains from two and one-half to five hours, the most digestible being lamb, beef, mutton, fish, veal, and pork, in the order named. Some starchy food, as rice, barley, tapioca, remain two hours or less in the stomach, while others, such as beans, peas, potatoes, re- main two and one-half hours ; white bread three hours, and brown bread four hours. Bulk or Volume of Food. — A bulky food throws ex- cessive work on the stomach, causes discomfort, and all parts of the food cannot so well come in contact with the walls. The same amount of nutriment in small space is more easily digested. One objection to a vegetarian diet is in the fact that the N is so diluted by insoluble cellulose and unnecessary starch, that large volumes of food must be taken to obtain the requisite fifteen to eighteen grms. of N daily. The carbohydrates, too, are apt to undergo fermentative changes, and the gases so formed give rise to flatulence and discomfort. The Reaction of Food. — As a rule, food should be slightly alkaline to excite a flow of gastric juice ; too much alkali, how- ever, neutralizes the gastric acidity and thus hinders digestion. Too much acid, such as lemon juice, vinegar, etc., may diminish digestion, and ultimately lead to serious disorders of the walls of the stomach. Cooking of Food. — The cooking of food is not always a necessity, although it serves several useful purposes. It destroys parasites and the danger of infection. It breaks up the starch grains in vegetable foods and makes them more easily affected by the digestive juices. It converts the insoluble collagen of ani- mal foods into soluble gelatin, and disintegrates the connective tissue. Of the two methods of cooking, roasting and boiling, the former is the most economical, as by its means the exterior is coated over with a coagulated coat which preserves the flavor and juices of the interior. Boiling renders the proteids more insoluble than they are in the raw state, but this is counter- balanced by the greater solubility of the connective tissue. 883. Artificiail Digestion. — It is frequently found necessary with persons of feeble digestion to partially digest the food before it is administered. Artificial gastric juice, pancreatic juice, and juices of the pawpaw plant and the pineapple are employed for this purpose. The food to be digested is warmed to the temperature of about 40° C. (104° F.). The digestive 542 MEDICAL CHEMISTRY. agent is then added, and it is allowed to react for a time limited by circumstances. In such food we present to the enfeebled stomach usually half-digested foods. In the case of meats, the peptonization is seldom carried to the formation of peptone. It is the aim usually to prepare peptone, if at all, in very small quantities. The best commercial preparations of so-called pep- tones are chiefly albumoses containing but a small quantity of peptone. Indeed, the value of peptone as a food seems to be about the same as albumose. Artifically digested foods are usually bitter if the digestion is carried too far. What this bitter substance is, is unknown. It is not albumose or peptone. 884. Absorption of Foods. — The absorption of the digested foods is more a physical and physiological process than a chemi- cal one. It is a process of osmosis, modified by special con- ditions. On one side of the mucous membrane of the intestines we have the blood and lymph, and on the other, a concentrated solution of easily diffusible salts, peptones, dextrin, Isevulose, soaps, and fat in a state of fine emulsion. The soluble carbo- hydrates, that is, dextrin, dextrose, laevulose, etc., absorb slowly and pass principally into the rootlets of the portal vein and are carried to the liver, where a part is stored up as glycogen, the remainder disappearing. The ultimate product of the hydrolysis of proteids, under the influence of pepsin and trypsin and known as peptone, is the most diffusible proteid known. It is absorbed partly by the lym- phatics, also somewhat by the blood-vessels, but is not found as peptone in the blood. If injected into the blood, it disap- pears inside of twenty minutes. If very large doses are injected, the animal suffers profound disturbances and usually death. Most of the peptone is reconverted into albumin while passing through the membrane. Very little unchanged proteid is ab- sorbed. Egg albumin, when mixed with a small quantity of sodium chloride, as well as myosin and alkali-albumin, is ab- sorbed in small amounts. The large intestine absorbs them more readily, the limit being 6 grms. of albumin or 50 grms. of egg white per day. The soluble soaps are easily absorbed. Very little of the fat undergoes saponification before absorption, but it is emulsified after a small amount of saponification. This emulsion is quite readily absorbed by the lacteals, and soaps can be detected in the portal blood, but rapidly disappear. No free fatty acids have been found in blood. Alcohol, in part, at least, tartaric, malic, citric, and lactic acids, glycerin, inulin, and vegetable mucin are absorbed from the intestine ; chlorophyll is FOODS AND DIET. 543 not absorbed; hematin only partly; indigo, madder, alkanet, tumeric, and many other vegetable coloring matters are absorbed. The gums and pectin, not being peptonized, are not absorbed. Poisons are sometimes rapidly absorbed and in others slowly. Some organic poisons are stopped by the liver while others are not. 885. Assimilation. — The function of food is to give heat and cell energy — mental, nervous, and muscular. The ultimate form of food as it leaves the body is HjO, COj, NH3, uric acid, and urea. The intermediate forms and products, besides those of animal heat and motion, are as y€t little known. Just what proportion of the food actually enters into the formation of the tissues before undergoing oxidation, and how much of it is oxidized merely to furnish heat, has been the subject of dispute, but the weight of evidence now seems to be that no proteid food is directly oxidized. Liebig divided food into flesh formers and heat producers. The nitrogenous elements he termed the plastic, or flesh formers. We now know that they produce heat and fat as well as the carbohydrates. Formerly it was supposed that the blood was the seat of oxidation in the body, but now this view is aban- doned. It is in the solid tissues where the principal oxidation takes place. While it is probable that the most of the food becomes assimilated and takes the place of the tissues which are disintegrated, it is certain, however, that not all of the food taken enters into the composition of the tissues, or is assimi- lated. It is quite probable that a part of the glucose, at least, undergoes direct combustion during the circulation in the capil- laries of muscular tissue during its contraction. We have seen that the proteids are all absorbed as peptones, are converted into serin or serum-albumin and serum-globulin, at or immediately after absorption, and circulate in the blood and lymph in this form. By slight modifications, which do not greatly modify the chemical composition, but rather their physical properties, they are converted into myosin, casein, ossein, gelatin, etc., to suit the needs of the different structures. These changes are due in many cases to loose combinations with various inorganic salts. The carbohydrates, we have seen, are absorbed in the form of dextrose. It is also stated by some authorities that a small quantity of dextrin and cane sugar may be absorbed from the stomach, when they enter the venous circulation. It is more likely that dextrose, when taken with food, is absorbed here, as it is more diffusible than either of the others. The dextrose which is absorbed from the intestines is changed 544 MEDICAL CHEMISTRY. by the liter into gl)'cogen, although this substance is also pre- pared from the proteids of the blood. Glycogen is also found in many other tissues, as in the fcetal placenta, the skin, lungs, kidneys, and epithelium. It is especially abundant in the muscles (0.4 to 0.8 per 100). It is augmented by a diet rich in starch, sugar, or dextrin. Dextrose is found in the muscle juice as well as in blood. The glycogen of the muscles accumulates during repose, but disappears during prolonged work, and may be one of the decomposition products of proteids. The fats are absorbed principally as such, and are distributed throughout the body. The animal body also derives fat from the conversion of sugar or glycogen, and from the destruction of albuminoids. The chemical processes involved in the appropriation of the various food substances we have been considering, are not thor- oughly known. But by some sort of combination the dead circulating proteid becomes a part of the living cell. The most important tissue of the body, because most abundant, is the muscular. Half the proteid material of the body and half the water exist in the muscles. We can get some idea of the use of foods by feeding experi- ments upon animals, and strike a balance sheet between the whole of the matter taken into the body in a given time, including food, drink, and air, and the total excretions, including urine, faeces, perspiration, and breath. The following table will illustrate what is meant by such a balance sheet : — EXCHANGE OF MATERIAL ON ADEQUATE DIET. {Ranke.) Income. Expenditure. Food. i u H i < Excretion. i n % i fa V. < Proteid, 100 grms., . Fat, TOO grms., . . . Carbohydrate, 250 grms., I5-S GO 00 53 79 93 Urea, 3 1.5 grms., . 1 Uric acid, 0.5 grm., / Faeces, ...... Respiration (COj), 14.4 I.I 0. 6.16 10.84 208.0 Totals, . . . '5 5 225 iS-5 225.00 FOODS AND DIET. 545 886. Relation Between Proximate Principles of Food. — It has been found that the relation between Carbon and Ni- trogen in our food should be 250 to 15, or 16.6 to i. The proportion of these elements in proteids is 53 to 15, or 3.5 to 1. If a man should attempt to live upon lean meat, he must consume 2 to 3 kilos (5 to 6 lbs.) of beef to get the requisite amount of carbon. This quantity would contain more nitrogen than the body needs and more than can be easily digested or oxidized if absorbed, and more than the kidneys can excrete. The over- working the kidneys would tend to produce chronic inflamma- tion, and the accumulation of nitrogen would tend to produce gout and other troubles. If the quantity of meat be adjusted for the proper amount of nitrogen, there would not be enough carbon to supply the waste, and the body would waste. A pure meat diet, therefore, cannot be maintained for a long time without serious injury. The same thing is true to a limited extent with carbohydrates in the form of cereals, and especially in the flour made from them. By reference to the table on page 533 it will be seen that to get the requisite nitrogen in wheat bread 1.3 kilograms (2.8 lbs.) of it must be eaten, while less than half that amount would fur- nish the carbon. In the practical construction of a diet, we first take enough meat to supply sufficient proteid, and then supplement this with sufficient carbohydrate and fat to furnish the necessary heat. The non-nitrogenous foods, i. e., fats and carbohydrates, are thus termed proteid-sparing foods. The same term may be applied to gelatin, as this is its chief value as a food. The fats and carbohydrates, especially the latter, oxidize more readily than the proteids, and in this way protect the proteids, as well as the fat, from loss. The fats and carbohydrates seem to be able, to a certain extent, to replace each other without detriment. Fats and carbohydrates are both manufactured in the body from pro- teids, but this change is prevented by an abundance of the former. In diabetes mellitus, this conversion of proteids into dextrose is very great, and with consequent rapid loss of flesh and strength. Supplying carbohydrates does not then spare the pro- teids. Fats are formed in the body for fattening purposes, from the proteids of the tissues as one of the retrograde. or destructive changes. Hence it forms a step in degenerations of tissue. Fats are also stored from the fat taken as food, or they are formed from carbohydrates. 887. Food Accessories. — By 'food accessories is meant. 546 MEDICAL CHEMISTRY. those substances taken with food, as alcohol, condiments, stimu- lants, etc. Alcohol, when taken in moderate amounts, is burned in the body, and gives potential energy. One gram of alcohol in burning produces 7.054 calories, while dextrin, which occurs with alcohol in malt liquors, gives 4. 117, and glucose 3.739. These substances are all capable of being used as combustibles. While alcohol acts as a producer of force, it, at the same time, cannot be regarded as equal to the carbohydrates. Like them, it spares the nitrogenous waste, shown by its power of diminish- ing the excretion of urea. In large quantities, however, it in- creases the excretion of urea, with the destruction of nitrogenous tissue. In this respect it behaves like certain active poisons, as arsenic and phosphorus. Like these poisons, it leaves a residue of fat after the decomposition of the tissues, and leads to the accumulation of fat in certain organs. There is another difference between the action of the carbo- hydrates and alcohol, and that is in the local irritant action of the latter on the stomach, other internal organs, and the central nervous system. While it serves to produce heat, spare the pro- teids, and stimulate the heart, it at the same time has a certain injurious action upon some of the tissues. Its paralyzing action upon the nervous system, is shown by the dilatation of the capil- laries, giving a sense of warmth in cold weather. This dilatation of the capillaries favors the loss of heat by radiation and a lower- ing of the general temperature. The larger the dose the greater its paralyzing effect upon the nerves controlling the capillary cir- culation and the greater the elimination of heat. The effect upon digestion, of a small amount of alcohol well diluted, is to assist it. The continued use of the stronger solutions (whiskey, brandy, gin, etc.) produces a catarrhal inflammation, and when used in excess, acute gastritis. The appetite very often either fails entirely, or is singularly modified to crave meats only, as a diet. This leads to the over-production of urea and uric acid, with gout, rheumatism, cystitis, or nephritis. Statistics based upon observations made upon thousands of men put under the same conditions, as in armies, have shown that " soldiers, in war or peace, in all climates, in excessive heat or cold, in rain and the' hardships of the severest marches, endure best when all alco- holic drinks are withheld." (A. Baer.) We must therefore regard alcohol as an expensive food, with certain good results when taken in reasonably small amount and well diluted, as in claret and beer, but when taken in larger FOODS AND DIET. 547 quantity it acts as a poison, which interferes with the normal metabolism, increasing nitrogen waste, and perverting the func- tion of digestion, nervous system, and some glandular organs. In this last case the net result of its action in the body is injurious. It has been estimated that the human body can burn about two fiuidounces of absolute alcohol per day. This will represent about 4 to 5 ozs. of whiskey or brandy, lo ozs. of sherry or port wine, 20 ozs. of claret, champagne, porter, or Bass's ale, or 40 to 60 ozs. of American beers. Tea, coffee, mate, and cocoa are used principally as nerve stim- ulants. The first three owe their stimulant properties to caffeine (tri-methyl-xanthin) ; cocoa to the related alkaloid theobromine (dimethyl-xanthin). It is noteworthy that &11 peoples in all climates make use of some plant that contains these or similar alkaloids. The most 'of the caffeine so taken is destroyed, but when the amount taken reaches 0.5 grm. (8 grs.) a portion of it passes into the urine. A cup of coffee, according to Bunge, contains about o.i grm. caffeine, and about the same amount is contained in from 2 to 10 grms. of dry tea leaves. Coffee has little influence upon the ex- cretion of urea and does not, therefore, act injuriously unless taken in doses sufficient to over-stimulate the nervous system. It does, however, sometimes act injuriously upon stomach digestion. The same may be said of tea and cocoa. Chocolate is not only a stimulant, but a rich food. It contains about half its weight of fat, and, besides, about 1 2 per cent, of albuminoid matter. It is, therefore, a concentrated food. Beef Tea and Beef Extracts owe their value to the ex- tractives which are stimulants and proteid savers. Some have regarded the inorganic salts as having a large share fn their re- freshing effects. They have little if any food value. The gelatin contained in soups and beef tea saves the waste of nitrogenous tissue during fever, and thus retards the loss of strength, but does not add to the construction of tissue or blood. Liebig's extract and similar preparations owe their effects prin- cipally to the extractives, creatin, xanthin, hypoxanthin, carmin, lactic acid, and inorganic salts. They contain about 78 per cent, of solid matter, of which about 60 per cent, consists of organic matters, principally composed of these extractives, and 18 per cent, of salts. Condiments, such as pepper and other spices, are useful only as means of whetting the appetite. They probably act by irri- tating the mucous membranes, causing an increased flow of the digestive juices. 548 MEDICAL CHEMISTRY. 888, The Source of Muscular Energy. — We have here- tofore spoken of the oxidation or burning of the food in the body, as the source of all heat, muscular power, and nervous energy. We have also seen that the food does not burn as such, but it supplies the place of tissue that has burned, and thus main- tains the equilibrium. When the body neither loses nor gains weight there is just as much food materials converted into tissue as there is tissue destroyed. The action of the food may be roughly ilhistrated by a tul)e open at both ends and filled with marbles. If we push a marble in at one end, one is pushed out at the other. If two or three are put in, two or three are pushed out. The marbles that are pushed out are equal in number, kind, and weight to those pushed in, but are not the same marbles. So the food enters the tissues on one side and crowds out waste products on the other. When more food is taken, more waste is crowded out and excreted. The changes that are observed when a muscle contracts are at first an elevation of temperature, an increase in the circulation in the muscle brought about by a dilatation of the capillaries, and the muscle becomes acid from sarcolactic acid. The eleva- tion of temperature is nearly proportional to the energy of the contraction or the work done by the muscle. It has been demonstrated that the muscle glycogen dimin- ishes rapidly during the contractions, and gradually accumulates when the muscle is in repose ; also that the glucose disappears from the blood flowing through a muscle when at work. Chau- veau showed by analysis of the blood entering and leaving the masseter muscle of a horse : First. That the amount of blood traversing a muscle is 2.5 to 3 times more during work than dur- ing repose. Second. The oxygen consumed by looo grms. of muscle, and the CO2 formed are 3]^ times as much during work as dur- ing repose. Third. That the glucose which disappeared from the blood passed through the muscle in a half hour, was 31^ times as much during work as during the same time in repose. At the same time the glycogen largely disappears from the muscle. The greater part of the real energy of a muS:le comes from the oxidation of glucose, or glycogen. A part of these bodies is changed into lactic acid, and a small amount of nitrogenous waste takes place, with the forma- tion of fat, creatin and other leucomains which accumulate in the muscle. DIGESTION. 549 It has not been demonstrated that urea or uric acid are much increased by muscular work, but the myosin and globulin seem to slightly diminish, and are probably converted into creatin, fat, etc. This explains why the urea excreted is not in proportion to the work performed by a man. The accumulation of leucomains, and the exhaustion of glycogen are the causes of fatigue. It has been shown that a laborer who works ten hours a day must have, to keep his body in a good state of health, over and above that necessary for a state of idleness, the following amounts^ of nourishment (Gautier) : — 42 grms. of albuminoids, giving 163 calories of heat. 12 " " fat, " 102 " " 160 " " carbohydrates, " 693 " " Total, 958 " From this it follows that 81 per cent, of the work done by the laborer comes from the burning of the fats and carbo- hydrates, and 19 per cent, from the albuminoids, which latter must be replaced by the food, molecule for molecule. The 42 grms. of albuminoids consumed, ought to produce 14 grms. of urea if entirely consumed and excreted in this form. In fact, only about one-sixth of this amount is obtained. There is, then, but a very small increase in urea excreted during work, over that excreted in idleness. Fick has demonstrated that about 33 or 34 per cent, of the total intramuscular combustion appears in the form of muscular work, while the remainder is thrown off as heat. This, indeed, is the principal source of animal heat. Helmholtz estimates that of the total heat pro- duced by oxidation in the body, about 7 per cent, is represented by mechanical work, and 74 per cent, is radiated and evaporated by the skin, and the remaining 19 per cent, by the lungs, urine, and faeces. DIGESTION. 889. Digestion has for its object the preparation of food for the nourishment of'th.e tissues. There is an external and an intersti- tial digestion. External digestion is the preparation of the food for absorption ; interstitial digestion is the more hidden process by which the food in the interior of plants and animals is modi- fied and made available for nutrition. External digestion is 55° MEDICAL CHEMISTRY. illustrated by the manner in which certain lower animals take their food, as, for example, the Amoeba, which rolls itself about its food, extracts the nutriment, and unrolls to allow the debris to escape. In the Venus fly-trap we have an example of the same process in plants. The alimentary canal is a prolongation- of the skin and may therefore be considered as being outside of the body. Reserves of food are such portions as are stored up in the bodies of plants and animals for future use, such as fat and glycogen in animals, and starch and sugar in plants. Digestion is carried on by means of soluble ferments or enzymes. The number of ferments employed in the digestion of food used by man is not accurately known. There are at least seven or eight of them. The following table presents these ferments, with their origin and the changeswhich they produce : — 8go. TABLE OF THE DIGESTIVE JUICES AND THEIR FERMENTS. Digestive Juice. Ferments Contained IN Them. Action on Food Materials. Saliva. Salivary diastase or Changes starch into dextrin and ptyalin. maltose. ( It. Pepsin. Changes proteids into peptones Gastric juice. \ in an acid medium. ( b. Curdling ferment. Curdles the casein of milk. f a. Trypsin. Changes proteids into peptones in alkaline and neutral media. b. Curdling ferment. Curdles the casein of milk. Pancreatic juice. c. Pancreatic diastase. Changes starch into dextrin and sugar. d. Emulsive ferment. Emulsifies and partially saponifies fats. Bile. ? Assists in emulsifying fats. ( a. Invertin. Changes cane sugar into invert Intestinal juice. sugar. (_ ^. ? Curdling ferment. Curdles the casein of milk. 891. The Saliva. — The first fluid to which aliments are subjected is the saliva. The saliva is the combined secretion of the parotid, submaxillary, and sublingual glands, mixed together, with mucus from the mucous membrane of the mouth. It is a slightly turbid, viscid, frothy fluid, without taste or odor, slightly alkaline in reaction, and of a sp. gr. from 1002 to 1008. DIGESTION. 551 It contains about .5 per cent, of solids, of which .2 per cent, is salts and the rest ptyalin, globulin, serum albumin, mucin, and salivary corpuscles. Mixed Saliva — Human. (Jacubowitsch.) (Hammerbachbr.) Per Cent. Per Cent. Water 99-Sl 92-42 Solids, 0.48 0.58 Soluble organic bodies (ptyalin, etc.), . 0.13 0.14 Epithelium, . . . 0.16 0.22 Inorganic salts, 0.182 0.22 Potassic sulphocyanate, 0.006 o 004 Potassic and sodic chlorides, . ... 0.084 • • • The alkaline reaction is due to the presence of bicarbonates and neutral phosphates. The alkalinity differs in different indi- viduals, and in the same individual at different times in the day, and may become neutral or acid without disturbance of the health, especially between the meals. Pathologically it may become more alkaline, or even decidedly acid. The salts present are HNaCOa, KCl,NaCl,KCyS,Na3P04, the sulphates and phosphates of cal- cium and magnesium, ammonium nitrate, and sometimes urea. It contains free O, N, and COj in solution. It is richer in CO2 than blood. On exposure to the air, the CO2 escapes, when some of the salts of calcium and magnesium are precipitated, accumulate on the teeth, and give rise to the deposit known as " tartar." The parotid secretion is clear and watery, rich in ptyalin and poor in mucin. The sublingual is richest in ptyalin, is strongly alkaline, is viscid, and traces of cholesterin and fat have been found. The submaxillary is more alkaline than the parotid, is rich in corpuscles and mucus, but poor in ptyalin. The saliva of irritation is alkaline and contains little or no ptyalin. The saliva is increased by stimulation of certain nerves, or by the irritation of pepper, alkalies, and food, or even the thought of food. It is increased by pilocarpine and eserine, but diminished by atropine. In the saliva of the newborn, only that secreted by the parotid contains ptyalin, while it appears in the submax- illary after about two months. Uses. — The saliva moistens and lubricates the food and con- verts starch and glycogen into maltose. The saliva acts best in a neutral or faintly acid solution, if the acidity be due to organic acids. It does not act in the presence of free HCl, or HCl and pepsin. Its activity is increased by small quantities of NaCl,Na2- S04(.4 pef cent.), NH4C1,C02, acetate of quinine, strychnine. 552 , MEDICAL CHEMISTRY. and morphine. Tea has an intense inhibitory effect, coffee and cocoa very little effect. The saliva becomes more alkaline in very acid conditions of the gastric juice, and even more abun- dant, giving the disease known as pyrosis, or water-brash. The saliva acts very feebly on uncooked starch. A peptone-forming ferment has been found in the saliva. 892. Gastric Juice. — The gastric juice is a thin, transparent, faintly yellow, acid fluid, of sp.gr. looi to loio. It contains from . 5 to I per cent, of solids, of which | or less is organic matter. The pyloric end of the stomach gives the alkaline fluid, or succus pyloricus, which is said to convert starch to sugar, and to digest albumin when acidified with HCl, and to dissolve gelatin. The thick slimy secretion of the stomach, in a state of rest, is neutral or alkaline. The normal secretion of the stomach is a mixture of these fluids. The daily quantity of the gastric juice is variously stated at from 16 to 31 pounds, or about 20 pints. Its composition is as follows : — ■ Analysis of Gastric Juice (Human) Mixed with Some Saliva. {After C. Schmidt.) Per Cent. Water . . . 99.44 Solids, . . 0.56 Organic substances (pepsin and peptones), . . . 0.32 Free hydrochloric acid, . . 0.25 Sodic chloride, ... 0.14 Potassic chloride, ... . . ... 0.05 Calcic chloride .... . 0.006 Phosphates of lime, magnesia, and iron, .... . 0.015 The acidity of the gastric juice of some of the lower animals, especially the dog, is greater than that in man. In the dog.it is nearly six times that of man ; in the fish it may even be seven times as much as that of man. The organic matter present is chiefly pepsin and a little mucin, and amounts to about .3 per cent. The acidity of the gastric juice is made up of hydro- chloric and organic acids. The organic acids are chiefly lactic and butyric, with occasionally acetic. These are not secreted in the gastric juice itself, but are produced partly by the decom- position of their salts in the foods taken, and partly by fermenta- tive action ; so that in the earlier stages of digestion the acidity is chiefly due to organic acids, but, in the later stages of diges- tion, chiefly to hydrochloric acid, which is present in quantities varying from .1 to .4 per cent. DIGESTION. 553 The hydrochloric acid is greatly diminished or entirely absent in the acute fevers during the fever, in chronic gastric catarrh with atrophy of the gastric glands, amyloid degeneration of the membrane, in all cachectic states, chlor- osis, certain nervous troubles, many forms of poisoning, Addison's disease, cancer of the stoinach, if it involves a considerable area, or is attended with catarrh of the mucous membrane, which is usually the case. It is absent, as a rule, in cancer of the stomach, and this fact is a valuable aid in the early diagnosis of this disease. The HCl is probably produced by one of the following re- actions: — (I.) 2NajHP04 + sCaClj = 2Ca3P04 + 2HCI + 4NaCl. (2.) CO2 + 2NaCl + H2O = Na^COj + 2HCI. (3.) NaHCOj + NaCl = Na^COj + HCl. Acid sodium Sodium carbonate. chloride. Others think that the HCl in the gastric juice is in combina- tion with some of the amid bodies, as leucin or tyrosin, which are found in all glands. Liebermann claims that there exists an acid-reacting compound of lecithin and albumin, always found in the mucous membrane of the stomach, which takes up the Na2C03 in the second, or the NaHCOj of the third reaction. The compound thus formed gradually sets free the NajCOa, which passes into the blood. Besides HCl and the organic acids above spoken of, the gastric juice contains ferments, two of which are of special interest, namely, pepsin and rennin or labferment. There exists also in the stomach at times, certain gases, especially CO,, O, N, H, and CH4. It is evident that these gases are the result of microbial fermentation of aliments. 893. Action of the Gastric Juice. — The gastric juice acts especially upon the proteids. It modifies them by transforming them successively into syntonin, or acid albumin, then into propeptones or albumoses, and finally into peptones. These compounds have already been described. It is evident from what has just been said, that during digestion a part of the HCl only is in the free state, while a part of it is in combination with albumin, in the state of acid albumin. The phenomena of gastric digestion are due to the hydration of the albumin, and a breaking up of molecules into simpler ones, so that the peptones are richer in H and O than the albuminoid bodies from which they were produced. 894. Chemical Examination of the Gastric Juice. — The chemical examination of the contents of the stomach has, in 47 554 MEDICAL CHEMISTRY. recent times, become an important aid in the diagnosis of dis- eases of the stomach. This generally includes an examination as to the rapidity of absorption, the motility, the reaction and acidity of the gastric juice, the determination of the kind and amount of acids present, an examination for syntonin and pep- tone, and the determination of the digestive activity. The juice for examination is obtained as follows : The usual method is to administer to the patient, on an empty stomach, an ordinary dry roll and a definite quantity, say 300 c.c, or about yi pint, of fluid, either simple warm water or weak tea without milk or sugar. The roll should be of a tolerably uniform weight of about 35 grms., or 540 grs. Such rolls contain about 7 per cent, of N, .5 per cent, of fat, .4 per cent, of sugar, 52.5 per cent, of non-nitrogenous matter, and about i per cent, of ash. This test-breakfast contains chiefly the albuminoids, sugars, starch, non-nitrogenous extractives, and salts. By means of this breakfast the stomach is given all the ingredients usually taken, with the advantage that they are liquefied in a relatively short period of time, or at least sufficiently liquefied to be capable of being easily drawn off through a tube. About one hour after taking the test-breakfast, the stomach tube is inserted, and that which remains in the stomach is drawn off. The amount ob- tained should be about 40 c.c, or ii/^ ozs. A greater variation than 15 to 20 c.c. in either direction should be regarded as pathological. The fluid thus obtained is filtered as soon as possible, and the tests are applied to the clear solution. The Acidity. — The acidity of the gastric juice is due to HCI, lactic acid, acid salts, and, occasionally, butyric or acetic acids. In the clinical examination, it is important to determine the cause of the acidity, as well as its amount. For this purpose various anilin dyes are found to be useful. Of these the best are Congo red and tropaeolin 00. Tropseolin is, when dry, an orange-colored powder, and in a saturated watery or alcoholic solution forms a dark yellow-red solution, which, in the presence of free acids, changes to reddish-brown, but with acid salts straw yellow. Even as little as .25 per 1000, or i in 4000, of free acid can be detected by this reagent. Congo red is also a sensitive reagent for the detection of acids. The solution is of a deep wine-red color, which changes to a sky blue with acids. It is more delicate than tropseolin, and will react to a fluid con- taining but .02 per 1000. Acid, salts produce no change. Benzo-purpurin is another color which has been used. It is also a deep red color, which changes with acids to a deep DIGESTION. sss blackish-blue color. If more than .4 per cent. HCl be present, the color produced is brown-black. If this color be employed in the form of test-paper, previously prepared by dipping un- sized paper in the solution and drying, we may distinguish between organic and inorganic acids, by placing a strip of paper which has been changed in color by the gastric contents, in a test-tube with ether. As the organic acids are soluble in ether, they dissolve out of the paper,' and the color produced by them will disappear, while if the color is produced by HCl, it will remain unaltered. Many prefer to use all these colors in the form of test-papers prepared as above described. A consider- able number of other colors have been recommended for the clinical testing of the gastric contents, but the ones here men- tioned are those most generally useful. The most delicate test for free hydrochloric acid is that known as the Giinzburg's test. The solution is made as follows : — Phlorogluciu, 2 grms. (30 grs.) Vanillin, I grm. (15 grs.) Absolute alcoliol, 30 grms. {i fl. oz.) This solution is pale yellow in color and has the odor of vanilla. It should be kept in blue or black bottles. It is em- ployed as follows : A few drops are spread out in a thin layer upon a porcelain dish or slab, which is then gently heated and a drop of the solution to be tested is allowed to flow across it, or a glass rod dipped in the solution is drawn across the plate. If free hydrochloric acid be present, a deep scarlet-red streak is developed. If the acid be very weak, no change is observed until the solution evaporates entirely to dryness ; blowing on the dish will cause the red streak to appear more rapidly. With this test it is unnecessary even to filter the gastric contents. This test is not simulated by the albuminoids, nor is it inter- fered with by acid salts, if present in the usual proportions, nor by organic acids. Its delicacy is such that it shows one part of HCl in 20,000 parts of water. Tropaeolin paper fails when the HCl falls below one part in 3500. The reagent of Boas seems almost as delicate as Giinzburg's. It is prepared as follows : — Resorcin, pure, S grms. White sugar, . . . 3 grms. Dilute alcohol, . . ... 100 grms. This reagent is employed in the same manner, and the indica- tion is similar to that above described for Giinzburg's reagent. 55 6 MEDICAL CHEMISTRY, The red color produced with it is positive proof of HCl, and is never produced by organic acids. 895. Detection of the Organic Acids. — There are two lactic acids met with in the stomach, sarco-lactic acid and fermentation lactic acid. Sarco-lactic acid is formed in the stomach from meat taken as food ; the other lactic acid may be formed by fermentation. A very simple and rapid test for clinical practice is that of Uffelmann. Dilute solutions of ferric chloride turn canary yellow in the presence of lactic acid. A still better solution is the following : A few drops of a dilute neutral solu- tion of ferric chloride are mixed with two drops of pure carbolic acid, and water added until the solution assumes a beautiful amethyst blue color. A few drops of a i in 2000 solution of lactic acid changes the color to yellow instantly. The delicacy of the reaction is very great. Lactates, as well as free lactic acid, unfortunately, produce this yellow color. It is said that alcohol, sugar, and certain salts can produce the same color. The test becomes certain if we first extract the organic acid from the gastric contents with ether, and apply the test to the residue left on evaporating off the ether. Acetic and butyric acids can usually be detected by the odor. The odor of acetic acid is usually unmistakable. It may also be detected by the use of ferric chloride, with which it gives a red color. Butyric acid changes Uffelmann's reagent to a tawny reddish color, and this only occurs when it is present in over 5 parts per 1000. Alcohol is found only in rare cases of yeast fermentation. 896. The quantitative estimation of the total acidity is best done by titration with decinormal alkali. Ten c.c. of the clear filtered liquid is diluted with 30 or 40 c.c. of water, a few drops of an alcoholic solution of phenol-phthalein or litmus solution are added, and the decinormal NaOH solution is run in from a burette (see Fig. 60) until a change of color is produced. As I c.c. of the decinormal alkali neutralizes 0.003637 grms. of HCl, and as we usually express the acidity in its equivalent in this acid, the number of c.c. of alkali used multiplied by this factor gives the amount of HCl, or its equivalent, in the 10 c.c. used. Thus if 6 c.c. alkali was used, the acidity will be 6 X .003637 = .021822 grm. in 10 grms. of liquid, or 0.218 per cent. The total acidity of the gastric juice is made' up of HCl, organic acids, and acid salts. As the organic acids are soluble in ether, they may be dissolved out before tritration, by shaking 10 c.c. of the liquid with 100 c.c. of ether. The acidity of the DIGESTION. 557 liquid then represents HCl and the acid salts. It is necessary also to distinguish the free acid from the HCl combined with the proteid as acid albumin. There may be an abundance of HCl in the liquid with but a slight acidity, as the most of the acid has combined with the proteids. The free acids may be estimated by the titration of lo c.c. of the fluid after treatment with i grm. of precipitated and thoroughly washed CaCOj. The free acids decompose CaCOj, while the acid salts do not. The acidity of the filtrate, after treatment with the precipitated chalk, gives that due to acid salts, which, deducted from the total acidity, gives the free acids. A simple ~and easy method of estimating the free HCl is to dilute the filtered fluid, that has given a positive reaction with Gunzburg's test, to ^, ^, ^, etc., until the test fails with the diluted solution. Since we know the, limit of reaction to be i in 20,000 (0.005 P^r i°o)j we can tell the amount of HCl present. Thus, if the red color fails with dilutions weaker than the ^, this will contain 0.005 X 20 = o. i per 100 or o.i per cent. Another method for obtaining the free HCl is as follows : If a mixture of organic acids and free or loosely combined HCl be treated with BaCOj, evap- orated to dryness, and reduced to ash, all the chlorine combines with the Ba as BaClj, which is soluble in water. The organic barium salts are decomposed during the ignition and do not go into solution, but remain as BaCOj. This solution is filtered and treated with NajCOj, which precipitates the Ba as BaCOg. This is filtered out and again dissolved in HCl. The excess of HCl is removed by evaporating to dryness, and the dry residue again dissolved in water, when the chlorine is estimated with decinormal silver nitrate, using potassium chromate as an indicator. One c.c. of the decinormal silver solution corresponds to 0.003637 grms. of HCl, from which the amount of HCl in the gastric juice taken may be calculated. For clinical purposes it is unnecessary to employ this somewhat complicated process. Hydrochloric acid may occur free in the contents of the stomach, it may occur combined loosely with the proteids, or it may occur as chlorides of inorganic bases. It is generally con- sidered important to estimate the free acid as well as that com- bined with the proteids. To estimate the free HCl, 10 c.c. of the filtered stomach contents are taken and titrated with a deci- normal soda solution, added from a burette, until Gunzburg's re- action no longer occurs. The alkali added corresponds to the amount of free HCl present. For example : If 10 c.c. of gastric juice no longer reacts with Giinsburg's reagent, after adding 1.3 c.c. decinormal soda solution, then the amount of free HCl is 1.3 times .003637 = .047 per cent. HCl. The loosely com- 5S8 MEDICAL CHEMISTRY. bined HCl may be estimated by continuing the above titration drop by drop after the failure of Giinzburg's reaction with congo-red as an indicator. 897. Estimation of Free HCl, Organic Acids, Acid Salts and Loosely Combined HCl, in the Same Solu- tion. — Ten c.c. of the filtered fluid, which has reacted positive with Giinzburg's test, is measured out, and y^ NaOH added, a few drops at a time until a drop of the solution fails to give Giinzburg's test. The reaction is now tested with a piece of Congo paper. If it shows no acid reaction, less than 0.02 per cent, of lactic or other organic acid is present. If the paper turns blue or lilac, continue to add the alkali solution until the red color of the paper is restored. The quantity of NaOH solution required after the failure of the Gunzburg test, to the changing of the Congo paper gives the lactic acid. Butyric and acetic acids would have been detected by the odor. The lactic, acid may be calculated as lactic acid, but it is usually expressed as HCl, or simply as the number of c.c. of NaOH solution required for 100 c.c. of the gastric contents. Thus if I c.c. be required for 10 c.c, we may say the lactic acid is 0.036 per cent., or that it is represented by 10 c.c. of NaOH solution. Having determined the end reaction with Congo paper, a few drops of phenol-phthalein may be added, and then enough alkali to produce a faint pink color. The amount of alkali now added gives the HCl combined with albumin plus the acid salts. The total amount added from the beginning gives the total acidity. By this one process, then, we determine the free HCl, the free lactic acid, and the loosely combined HCl and the acid salts. When the Congo paper gives a negative test, after Giinzburg's test has failed to show free HCl, there are no free organic acids. If the filtered gastric contents should show a negative test with both Congo and Giinzburg's reagent, the titration is begun upon 10 c.c. with decinormal HCl solution. This is continued until Congo paper shows a faint blue coloration, and the quantity used noted. The Giinzburg test is now applied. If a positive test is obtained, no organic acids are present. If negative, more HCl is added until the test is positive. The number of c.c. of deci- normal acid added, after the positive reaction with Congo is ob- tained, to the positive reaction with Giinzburg's reagent, will indicate the lactic acid in the 10 c.c. Usually, lactic acid is not detected by Uffelmann's test, DIGESTION. 559 or by titration in specimens obtained one hour after Ewald's test-breakfast. The titration, however, is best carried out in every instance. Accepting o. 2 per cent, as the average amount of HCl contained in stomach contents during digestion, we are able to detect by titration even very slight variations from the normal. In normal digestion the free HCl should require from 40 to 60 c.c. of decinormal NaOH solution, for 100 c.c. of the fluid, while the total acidity should not require more than 75 to 80 c.c. of alkali. 898. Syntonin or Acid Albumin, Albumose and Pep- tone. — These are recognized by the biuret test. The filtered fluid is rendered strongly alkaline with NaOH or KOH and a few drops of a solution of a CuSOi added. A red or violet color indicate the presence of one of these substances. The presence of peptones necessarily indicates the presence of diges- tive power in the stomach. Syntonin, or acid albumin, may be detected by simple neutralization of the filtrate, when it is pre- cipitated. Albumoses may be shown to be present if the filtrate from the precipitate of syntonin, or the liquid in the absence of syntonin, is saturated with ammonium sulphate. Albumose is precipitated as a white cloud, soluble on warming. The filtrate from the precipitation of the albumose may be tested for pep- tone by the biuret test, or by the addition of picrid acid solution, which precipitates peptone. 899. The Ferments, Pepsin. — The test for pepsin is accomplished by the addition of coagulated egg albumin to the filtered gastric contents, and keeping this mixture at a tempera- ture of about 40° C. (104° F.) for a definite time, and noting whether the albumin is corroded. If the gastric contents have been found by the above test to be destitute of sufficient HCl, enough should be added to bring the quantity up to about 2 parts per thousand. Coagulated albumin discs, made by cutting the white of boiled eggs in thin flakes of uniform thickness, and punching out by means of a cork borer or glass tube, and pre- served in glycerin, are best used for this purpose. The presence of rennin is best shown by carefully neutral- izing 5 c.c. of the filtered gastric contents, and mixing this solution with an equal volume of carefully neutralized milk. If rennin be present, the milk is coagulated in a few minutes. 900. Rapidity of Absorption from the Stomach is tested by giving the person a capsule containing o.i grm. of potassium iodide and then testing the saliva for the iodine re- 560 MEDICAL CHEMISTRY. action. With a normal stomach, iodine appears in the saliva 10 to 15 minutes after giving the capsule. The iodine is detected in the saliva as follows : Strips of filter paper are soaked in starch mucilage and dried. One of these papers is pressed upon the tongue, removed, and then touched with a glass rod previously dipped in some yellow nitric (nitrbus) acid. The appearance of a blue spot shows the presence of iodine. 901. The Motility or Motor Function of the stomach is a matter of importance, and its determination is sometimes required. When the motility is normal or increased, the food, even if it is not digested, is passed on into the duodenum before any disturbance arises from lack of digestion. The motor function may in this way compensate for lack of digestive power in the stomach. The lack of proper motor power, on the other hand, may produce dyspeptic symptoms where the digestive power is normal, because of the long delay of the food in the stomach, with secondary fer- mentations. Ewald's Salol Test is the best test of the motility of the stomach. It does not decompose until it reaches the duodenum, when it forms phenol and salicylic acid, which latter is then ab- sorbed and appears in the urine from 60 to 75 minutes after taking about 0.6 to i grm. in a capsule. Or, we may note how long the salicylic acid continues to be eliminated by the urine. If the reaction shows the acid in the urine at 30 hours or longer, it may be regarded as proof of deficient motility of the stomach. Salicylic acid is easily detected in the urine, by wetting a piece of filter paper with this fluid, and dropping on the moistened spot a drop of a 10 per cent, solution of ferric chloride. The edge of the drop will assume a violet color in presence of traces of salicylic acid. These papers may be dried and preserved, if necessary, as records of the test. Klemperer pours 100 c.c. (3^ ozs.) of pure olive oil into the empty stomach, and removes with the stomach tube what remains after two hours, to determine how much has been passed into the duodenum. 902. The Pancreatic Fluid. — The pancreatic fluid is the secretion of the pancreas, poured out into the duodenum at the junction of the middle and lower third of the duodenum through the pancreatic duct. In some lower animals there are two ducts. The rabbit, dog, and cat each have two ducts. The pancreatic juice is a transparent, colorless, odorless, saltish, alkaline fluid. DIGESTION. S6i effervescing with the acids. It is composed of water 90 per cent, and of solids 9.93 per cent. There are few cells, if any, in its solution, and it is, therefore, clear. The pancreatic fluid has at least three ferments, or zymogens that furnish at least three fer- ments ; the diastasic ferment, amylopsin, allied to if not iden- tical with ptyalin, trypsin, a peptone-forming ferment, and pyalin, a saponifying ferment. The secretion of the pancreatic juice begins as soon as food is taken, increases for two hours, then falls, and a second rise takes place in from 5 to 6 hours, when it falls again to o in about 18 hours, if no more food be taken. The most marked charac- teristic of- the pancreatic secretion is that it acts in neutral or alkaline solutions rather better than in acid solutions. A slight excess of HCl destroys it entirely. Its most marked action is upon proteids and starches, converting the former into peptone with certain side products, and the latter into maltose, which is afterward rapidly changed into glucose. Pancreatic digestion differs from peptic digestion in certain well-marked features which are shown below : — Active Pepsin. — Acid Medium. Pancreatin. — Alkaline Medium. Fibrin swells before dissolving. Fibrin corroded away. Assisted by HCl. Assisted by NajCOj. Destroyed by NajCOj. Destroyed by HCl. Forms syntonin, albumose, and Forms alkali albumin, antipeptone, peptones. hemipeptone, leucin, tyrosin, hy- poxanthin, and aspartic acid. Acts best on albumin. Acts best on fibrin. The pancreatic fluid is the chief digestive fluid concerned in the complete digestion of starch. It contains the ferment amylopsin, or pancreatic diastase, which readily converts starch into maltose and finally into glucose. The extract of the pancreatic gland is exceedingly active in its effect upon cooked starch. This secretion in the newborn is destitute of amylopsin, which makes its first appearance at about the end of the second month. Previous to this time, infants cannot usually digest starch. Some infants, however, seem to be endowed with the property of digesting starch, and it would seem, therefore, that they must secrete some diastase, either in the saliva or the pancreatic fluid. The milk-curdling property of the pancreatic fluid is less marked than in the case of the gastric fluid. Of the fat-splitting ferment little is known, except that a special ferment exists in the pancreatic juice which has this property. It decom- 48 562' MEDICAL CHEMISTRY. poses lecithin into neurin, and saponifies fats to a slight extent only, but sufficient to assist in the formation of a perfect emul- sion. A small amount of free acid in the oil greatly assists its emulsification with a dilute solution of sodium carbonate. For this reason a slightly rancid oil emulsifies more readily than a neutral oil. 903. The Succus Entericus is the digestive fluid secreted by the mucous glands of the intestinal mucous membrane, princi- pally by Lieberkuhn's and Brunner's glands. The secretion from Brunner's glands contains proteids, mucin, and ferments. It dissolves proteids, slovifly changes starch to sugar, changes maltose to glucose, and iiiverts cane sugar. It is a light yellow, opalescent, strongly alkaline fluid. The succus entericus is most active in the dog. Its diastasic power is less than that of the saliva or the pancreatic fluid, and when it acts upon starch it forms glucose instead of maltose. The large intestine contains none of this ferment. 904. The Bile. — The bile is a viscid, transparent, golden- yellow colored liquid secreted by the liver. It has a bitter taste and alkaline reaction. Specific gravity, 1009 to 1020. Its composition is highly complex, but is represented principally by the following : — Per Cent. Per Cent. Water, . 91.68 Soaps, . . Mucus and pigment, . . . .129 Fat, . . Olycocholate of sodium, . ■ 3-"3 Lecithin. . Taurocholale of sodium, . . 0.87 Cholesterin, 1.39 •73 •S3 ■35 The amount of bile secreted in 24 hours is variously staled at from 1000 to 1700 grms., or from .23 to 47 ozs. The bile is prepared in the liver from the large amount of blood received by it. More is secreted during digestion than during fasting, and the per cent, of solids increases during digestion. In abstinence from food, or with a fatty diet, little is secreted ; more is secreted with bread and rice, still more with meat, but most with a mixed diet. The bile is stored in the gall bladder when not needed, and poured into the duodenum near the point of exit of the pan- creatic duct. On standing, the bile becomes of a brown-yellow color and readily undergoes decomposition. The constituents of the bile are described elsewhere. The functions of the bile are : — First. To assist in emulsifying fats and, in the presence of the pancreatic juice, it assists in saponifying a small portion. THE FjECES. 563 Second. It readily wets the mucous membrane, dissolves fats, and assists in their absorption. Third. Checks putrid fermentation in the intestines. Fourth. It precipitates the pepsin, syntonin, albumoses, and peptones from the chyme, and stimulates the production of intes- tinal juice. Fifth. It contains a diastasic ferment which converts starch into sugar. Sixth. The bile stimulates the contractions in the muscular coat of the intestines and villi, increases the moisture in the in- testine, acts as a lubricant, and favors the passage of the con- tents of the small intestine. A considerable portion of the bile is re-absorbed; apart of the coloring matter at least being excreted by the kidneys, while a part passes out with the faeces. The biliary acids are mostly absorbed from the ilium and jejunum, only a trace being found in the faeces. Toxic Effects. — Obstruction to the discharge of the bile leads to its absorption by the lymphatics, giving rise to cholaemia, or absorptive jaundice. The coloring matter passes into the cir- culation and stains the tissues yellow. The effect upon the heart is to produce a slow pulse and respiration, low temperature, irri- tation of the skin, lassitude, headache, and coma. THE F.ffiCES. 905. Chemical Composition of Faeces. — An adult, upon a mixed diet, passes about 120 to 150 grras. of moist excrement in twenty-four hours. A vegetable diet increases the weight. If much indigestible food be taken, it may be as much as 500 grms. The consistency depends upon the amount of water present, which is usually about 75 i)er cent. A pure flesh diet gives a relatively dry faeces, while substances rich in sugar yield faeces with a relatively large amount of water. The quantity of water taken has no influence upon that found in the faeces. The water in the faeces seems to be in direct ratio with the energy of the peristalsis. The faeces have a neutral, sometimes alkaline, and rarely acid, reaction. The alkalinity is derived from the ammoniacal fermentations, while the acidity is from the lactic and butyric acid fermentations. Acetic and propionic acids have also been found in the faeces. The copious secretion of mucus favors the occurrence of the neutral or alkaline reaction. 564 MEDICAL CHEMISTRY. The color depends upon the amount of altered bile pigment mixed with them, to which the .bright yellow to dark-brown color is due. The color of the food is sometimes imparted to the faeces. If much blood be present, that is, after hemorrhages, the faeces are brownish-black from heraatin. Preparations of iron, bismuth, or lead, taken by the mouth, color the faeces black from the formation of the sulphides of these metals. Some green vegetables impart a brownish-green color, due to chloro- phyll. The green color of infants' faeces is believed to be due to butyric and lactic fermentation, and the action of these acids upon the biliary coloring matters. In adults green passages may be due to a green microscopical plant, or chlorococcus. The disagreeable odor of normal faeces is due in great part to indol and skatol. These are products secreted by the putrid bacteria, and come from the decomposition and transformation of albuminoid matters. Hydrogen sulphide, and sometimes a trace of hydrogen phosphide, contribute to the odor of faecal matter. The faeces contain, first': Alimentary substances which are assimilable, but which had been taken in excess, as starch, fatty matters in notable quantities, and a small proportion of non- assimilable proteids. Second. Indigestible substances, such as vegetable fibre, cellulose, chlorophyll, gums, pectic substances, resins, elastic tissue, epidermic tissue, tendons, diverse coloring matters, nu- clein, chittin, insoluble salts (silicates, insoluble sulphates, am- monium magnesium phosphate, and calcium phosphate). • Third. Products coming from the digestive tube itself; in- testinal mucus, epithelial cells, biliary acids (in part transformed as above described), cholesterin, lecithin, and bacteria. Fourth. Substances which failed of absorption, as emulsified fatty matters, the free fatty acids, leucin, and biliary acids. Fifth. Decomposition products due to microbic action, as the free fatty acids from acetic up to palmitic, this last quite abundant; also butyric, isobutyric and lactic, phenol, cresol, indol, skatol, stercorin, excretin, ammoniuni carbonate and sul- phide, amins, amids, ptomains, leucin, tyrosin, phenylpropionic, phenylactic and parahydroxylphenylactic acids. Some of these bodies, especially the ptomains, acids, phenols, and coloring matters, are absorbed, the phenols passing into the urine in com- bination with sulphuric acid as sulphuric ethers. Sixth. Pigments. The pigments found are stercobilin, heraa- tin, biliary pigments, hydrobilirubin, and food-coloring matters. Seventh. Gases. The origin of the gases of the intestine is THE FMCES. 565 partially from fermentation, partially from air swallowed with food and drink, and partially from diffusion from the blood or other tissues. The gases are composed of hydrogen, nitrogen, carbon dioxide, and marsh gas. The composition varies con- siderably with the character of the food and the character of the fermentation, the length of time the food remains in the diges- tive canal, and the activity of the digestion. The discharge of carbon dioxid, frequently very great, which is rapidly produced in hysterical persons, probably comes from diffusion of the gases from the blood into the intestine and stomach. Marsh gas is derived from the fermentation of cellulose and other similar bodies. The nitrogen gas comes partially from swallowed air, but in small part from the blood and putrefactive fermentation. The following figures give the analysis of 1000 parts of fresh excrement :-^ Adult Man. Infant. Water, 733. 851.3 Fixed solids, 267. 148.7 Total organic matter, 208.75 '57-' Mineral matter, 10. 95 13.6 Alimentary residue, 83. . . The analyses of excrement have their importance principally, as a guide to the assimilation or malassimilation of food, and also because the excrement of various animals is employed as a fertilizer. The meconium, or the residue which accumulates in the intestinal canal during foetal life, and which is passed soon after birth, contains bilirubin and biliverdin in abundance, also biliary acids, some fatty acids, the alkaline sulphates, chlorides, and the phosphates of calcium and magnesium. It does not con- fain urobilin, glycogen, peptone, lactic acid, leucin, or tyrosin. Two peculiar substances are found in fseces which do not occur elsewhere in the body. These are excretin and stercorin, or serolin. Excretin may be obtained from the fseces by making an alcoholic extract, and keeping it for a considerable time at a temperature below 0° C. (32° F.), when there is deposited an olive-colored granular body, having a faecal odor and acid prop- erties, from which Marcet has named it excretoleic acid. It resembles cholesterin in its properties. Stercorin is a body closely resembling cholesterin, and has frequently been con- founded with it. It may be obtained from the dry faeces by ex- hausting with ether, filtering through animal charcoal, and allow- ing the ether to evaporate. Stercorin is left in the form of small, needle-shaped crystals, frequently in radiating groups. 566 MEDICAL CHEMISTRY. MILK. 906. The milk is the secretion of the mammary glands, the presence of which is characteristic of the mammalia. The milk of different animals differs somewhat in composition, but always contains the same constituents. It contains all the necessary constituents of a perfect food, and is intended for the nourish- ment of the young until they are able to live upon other foods. Milk is. an opaque, white fluid, containing fat globules in suspen- sion, albumin, sugar, and salts in solution, and casein in partial solution. The reaction of human milk is generally feebly alkaline; that of the cow is usually neutral or faintly acid, while that of the carnivora is generally acid. Milk readily becomes acid or sour on exposure to the air, due to lactic fermentation. Microscopical examination reveals the fat in a state of perfect emulsion, the fat globules remaining suspended and separate from one another. The fluid seen between the globules is not perfectly clear, but contains small granules of casein, which may be filtered out by passing it throt^igh a clay filter. The milk which is secreted for the first few days after parturition, shows the presence of a few corpuscles of a peculiar character. These corpuscles seem to be epithelium cells containing fat globules, which they have not yet liberated. These cells are called colostrum cor- puscles, and the milk of the first few days of lactation is called colostrum. It is believed by some that each fat corpuscle is surrounded by a shell, or membrane, of casein. Others deny the existence of this membrane. The specific gravity of milk is usually determined with the hydrometer. The specific gravity of cow's milk varies from 1029 to 1035. An excess of fat lowers the specific gravity, and the removal of fat raises it. The addition of water will lower the specific gravity. These facts are made use of for the detec- tion of the ordinary adulterations of milk. The amount of milk secreted varies with the health of the animal, the amount of food taken, and various other conditions. The amoiint secreted by a woman each day is about i liter. A good cow secretes about 7 to 10 liters. The composition of milk varies in different classes of animals, with the state of nutrition of the animal, the constitution, the age, the period of lactation, and the character of the food. 907. Composition of Milk. — The published analyses of milk are very numerous, and the older analyses made by older methods differ somewhat from the analyses made by more recent 56; methods. The comparative composition of the milk of different animals is given in the following table: — Analysis of Human Mri.K and Cow's Milk (Konig). Woman's Milk. emu's Milk. Mean. Minimum Maximum. Mban. Minimum. Maximum Water, . . 87.09 83.69 90.90 87.41 80.32 91.50 Total solids, 12.91 9.10 16.31 11.59 8.50 19.68 Fat, . . 3-9° 1.71 7.60 3.66 I.15 7.09 Milk sugar. 6.04 4.II 7.80 4.92 3.23 5.67 Casein, . . 0.63 0.18 I. go 3-ot 1. 17 7.40 Alliumen, . I-3I 0.39 2.35 0.7s 0.2t 5 -04 Albuminoids, ■ 1-94 O.S7 4-25 376 1.38 12.44 Ash, . . . - 0-49 0.14 ? 0.70 50 0.78 Besides the constituents mentioned in the table, milk also contains very small quantities of certain extractives, among which are creatin, leucin, the odorous principle, etc. It also usually contains certain gases, principally carbon dioxide, oxy- gen, and nitrogen. Colostrum contains a larger proportion of solid matter than ordinary milk, a larger amount of albuminoid materials, and less sugar. The proteids which occur in milk are probably three in num- ber — caseinogen, lactalbumin, and lactoglobulin. Lacto-protean and peptone have also been described by some observers. When milk is allowed to stand at the ordinary temperature, a part of its lactose is converted by fermentation into lactic acid. When this has accumulated to a certain extent, the caseinogen is pre- cipitated. When milk is treated with rennin, or gastric juice containing this ferment, the caseinogen is rapidly converted into casein, and at the same time coagulation or precipitation occurs. When rennet is added to cow's milk, the result is a coherent clot or curd and a clear yellowish fluid called whey. The curd contains the fat entangled with the casein. The whey contains the albumin, sugar, and salts. In human milk the curd is formed of smaller flocculi, and the same appearance may be produced with cow's milk, if it is previously boiled or diluted with lime water. Caseinogen is often compared to alkali albu- min ; the latter, however, does not coagulate with rennet, and is readily soluble in acids, while caseinogen is not. Caseinogen resembles the globulins somewhat in its behavior with neutral salts. The globulins, however, coagulate when heated, while caseinogen does not. Casein. — This name is sometimes restricted as above to the 5 68 MEDICAL CHEMISTRY. proteids formed by the action of rennet and acids, from case- inogen of milk. Casein is the chief constituent of cheese. Lactalbumin. — After the precipitation of the casein by acetic acid, this proteid is left in the solution. The scum which forms on the top of milk on boiling is probably formed by the coagulation of a part of the lactalbumin. The boiling of milk before it is used as food is advantageous, in that all germs of disease are destroyed, and that the rennet gives a floccular instead of the heavy curdy precipitate. The lactalbumin is modified by the boiling, and precipitates on add- ing acid to the cold boiled milk. Lactoglobulin. — Various observers have discovered other proteids than the two mentioned above. Lactoglobulin, whey proteid, lactoprotein, proteoses, peptones, and nuclein have been mentioned as occurring in milk, but our knowledge of them is so slight that we will pass them with the mere mention. The lactoglobulin has the property of liquefying cooked starch, and of partially digesting it. This property is destroyed by sterilization. Fat.— -The chemical composition of milk fat is very nearly like that of adipose tissue, with small quantities of the triglycerides of butyric, caproic, caprylic, myristic, and arachinic acids. Milk also contains minute quantities of lecithin, cholesterin, and yellow lipochrome. Cream is simply the upper layers of milk which has been left to stand, and in which the fat globules are more numerous than in all milk. The amount of cream that will separate from the milk in 24 hours is sometimes made use of as a test for the richness. A fair market milk will give from 10 to 12 per cent, of cream, while good milk will frequently give from 15 to 20 per cent. , or even more. Butter is the fat of milk in which the fat globules are broken up by mechanical agitation in the churn. About one-sixth of the fat remains in the buttermilk. Buttermilk contains, there- fore, about from 0.5 to i per cent, of fat. Butter also contains small quantities of casein and lactose. Butter from human milk is richer in fluid fats than that made from cow's milk. By exposure to the air, butter becomes rancid, due to the breaking up of some of the glycerides of the fatty acids. Milk Sugar, as will be seen in the above table, occurs to the extent of about 4.5 per cent, in cow's milk, and about 6 per cent, in human milk. The characteristics of this sugar have been described in Part V. MILK. 569 The Salts of milk are the phosphates of potassium and sodium, calcium, and magnesium, with chlorides of potassium and sodium, and a trace of iron, which is in combination in the nuclein. 908. Sterilized and Pasteurized Milk. — Owing to the ease with which milk undergoes the lactic fermentation and be- comes sour, various methods have been tried to preserve milk for use in large cities. Subjecting the milk to a low temperature has been in use for a long time, and is of great service. Milk kept at a temperature of about 10° C. (50° F.) will keep sweet for a number of days. For use as a food for infants, this has been found to be imprac- ticable. Even with the greatest precaution, the lactic ferment will slowly progress and will grow in such abundance, as soon as the food is taken, as to disturb the child's digestion. This may and often is prevented by heating the fresh milk to 100° C. (212° F.) for 15 to 20 minutes, and then closing it up in an air- tight bottle or jar until needed for use. This " sterilized milk " is to be found in the markets. It has not met the success in use that was at first expected. The heat coagulates the lact- albumin, the globulin, and modifies the casein. On acidifying sterilized milk all the proteids are precipitated at once in a firm curd that does not afterward digest, but appears in the faeces. Experience shows that children fed upon this milk do not thrive. The' temperature at which these changes in the proteids begin is about 75° C. (167° F.). If milk is. heated to this temperature, and not above, many organisms are killed, and others so weakened that the keeping quality is greatly improved, without altering the taste or composition. This process is called Pas- teurization, and is now used to preserve milk for use as a food for infants. 909. Modified Milk. — By this term is meant cow's milk that has been changed in composition so as to resemble the composition of human milk. As the caseinogen of cow's milk is about three or four times that of human milk, and the albumin is but half that of human milk, there is a very decided difference in the digestibility of the two. Rennin coagulates the caseinogen only. The curd formed in the stomach from cow's milk is more abun- dant and forms tough masses, difficult to digest, while that from human milk is slight in amount and flocculent. The sugar of cow's milk is present in about 4.5 percent., while that of human milk is nearly 2 per cent, higher. These 57° MEDICAL CHEMISTRY. differences in composition make it necessary to modify the com- position of cow's milk for the successful nourishment of many infants. Various methods have been proposed for accomplish- ing this, and have led to the production of numerous prepara- tions put upon the market as baby foods. The most successful of the attempts to modify cow's milk to imitate human milk is a mixture of milk, cream, water, lime water, and milk sugar, made to correspond to the average analysis of human milk, and then Pasteurizing the mixture. The milk used for this process, as well as the cream, must be fresh, and the cream should be of nearly constant composition. The only way to secure this is to use cream separated by the centrifugal machine. With such a cream, containing 20 per cent, of fat, the follow- ing proportions will give very nearly the composition of average human milk (Rotch) : — Milk, 2 parts, or. Milk 4 fluid ounces. Cream 3 parts. Cream, 6 fluid ounces. Water, 10 parts, Water, . ... 20 fluid ounces. Lime water, i part, Lime water, ... 2 fluid ounces. Milk sugar ^ part. Milk sugar, ... 7 drachms. It is generally thought best to add the lime water at the time of feeding, but the author has usually added it before Pasteur- izing. The analysis of the above mixture will be about as follows when a good milk is used : — Water, .... 88.42 Fat 4 Sugrr, . . 6.26 Solids,. . . 11.58 Albuminoids, . 1. 11 Ash, 0.21 The albuminoids in this mixture are too small in amount for most children after the first three months, and the milk and cream should then be used in equal volumes, for practical experience has shown that children thrive better on the latter proportions. 910. Changes in Milk Produced by Disease. — The milk of a strong, healthy woman is more nourishing than that of the weakly, sickly woman. The character of the secretion of milk in the human subject, as well as in some of the lower animals, is greatly varied by the emotions, and inilk secreted during periods of excessive mental excitement has frequently proven poisonous to the young. Certain drugs pass through the mother into the milk, as, for example, iodine, arsenic, anti- mony, lead, zinc, bismuth, and mercury. Opium and morphine. MILK. 571 although they may not be detected in the milk, have frequently passed into the milk in sufficient quantities to narcotize the infant. In the cow the character of the food and the state of the health has an important bearing on the composition of the milk. In cases of the cattle-plague the milk has been found to contain blood. The milk in cases of tuberculosis, a common disease in cows, is capable of communicating this disease to calves, as well as to human subjects. Milk from tuberculous cows should never be used. The milk from foot-and-mouth dis- ease is also injurious. Milk is often the carrier of the infectious or contagious diseases, as measles, scarlet fever, diphtheria, smallpox, and typhoid fever. Milk is a good cultivating medium for the growth of various bacteria, and several characteristic bacteria occur in milk pro- ducing coloring matters, one giving it a blue, another a purple- red, and another a yellow color. Milk is sometimes rendered poisonous by certain bacterial growths. These poisons are either ptomains or toxic albumins produced by the growth of these bacteria. gii. The Adulterations of Milk. — The adulterations usually practised are the extraction of cream and the addition of water, or both. Occasionally the addition of some foreign substance, as sodium carbonate, common salt, or sugar, is met with. The detection of the adulterations of milk usually depends upon the determination of the specific gravity, the fat, total solids, and the ash. The quantity of these ingredients is not perfectly uni- form, and hence certain limits of allowable variations have been determined "upon from time to time. The standard adopted in many States in this country is, for specific gravity, not less than 1029, for total solids not less than 12 per cent., of which 3 per cent, shall be fats. The legal limits for total solids vary from 12 to 13.13 per cent., and the solids not fat from 8.5 to 9.5 per cent. The Society of Public Analysts of Great Britain have adopted for total solids, 11.5 — fat, 3, and solids not fat, 8.5 per cent. Milk Testing. — There is no instrument of simple construc- tion which will with certainty detect the presence of a small amount of adulteration in milk. The lactometer, or lacto- densimeter, which has been employed very largely in the sanitary in.spection of milk, is a hydrometer with a scale cpver- ing the variations usually met with in milk. (See Fig. 56.) The lactometer of the New York Board of Health is a hydro- 572 MEDICAL CHEMISTRY. meter on which the scale is so constructed that ioo° indicate a specific gravity of 1029, the supposed lowest specific gravity of pilre milk. ' The space between 1000, the specific gravity of water, and 1029 is divided into 100 arbitrary degrees. The scale is extended, to 120°, which corresponds to a specific gravity of 1034. When taken alone it is of very little value. If, however, it be taken with the estimation of either the total solids or the fat, it is of considerable service. In very excep- tional cases the milk of a single cow may have a specific gravity below 1029, but such milk should be regarded as abnormal. Fig. 56. Fig. 57. Hydho- Creamo- ' %r • METER. METER. Feser's Lacto- {S^arr.) {Siarr.) SCOPH. {Queen.) Such depression of the specific gravity never occurs in the mixed milk of several well-fed cows. A specific gravity below 1029, therefore, unless accompanied by an excessive amount of fat, may be taken as evidence of contamination, probably with water. The fat for such examinations may be estimated by the creamometer, or by some form of lactoscope, or the lacto- butyrometer. The creamometer, or cream gauge, is simply a graduated cylinder, the graduations being -j^ of the total capacity of the cylinder to the o mark. (See Fig. 56.) The milk is added in the cylinder to this zero mark, and allowed to remain at rest for twenty-four hours, when the MILK. 573 number of the divisions covered by the cream is read off. This should not be less than lo per cent. The lactoscope depends upon the fact that the opacity of the milk is proportional to the amount of fat which it contains. In Feser's lactoscope (Fig. 57), a measured volume of milk is placed in a graduated vessel, A, by means of the pipette, B. It is then diluted with water until the black lines of the inner cylinder of opaque white glass can be seen through the layer of the mixture between the walls of the inner and outer cylinders. It is then only neces- sary to read off the per cent, of fat on the scale of the outer cylinder. This method of determining the fat in milk, although answering for the purpose of municipal control, is not to be depended upon for scientific purposes, or as evidence upon which to base legal proceedings. The lactoscope is of value in estimating the fat in human milk for clinical purposes. In a large experience with this instrument the author has seldom seen the readings vary more than .3 per cent, from the accurate methods. Usually it is much nearer than this. 912. The Chemical Analysis of Milk. — An easy, rapid, and satisfactory method for estimating the fat in milk is that known as the 'Werner- Schmid Process. Ten c.c. of the milk are measured out into along test tube, holding 50 c.c. and graduated at every 10 c.c, and treated with 10 c.c. of strong HCl. If desired, the milk may be weighed into a small beaker glass and then washed into the test tube with the acid, when the test tube need not be graduated. After mixing the milk and acid together, the mixture is brought to a boil, or it is corked and heated in a water bath for 5 or 10 minutes, or until the liquid turns brown, but not black. The tube and contents are then cooled and 30 c.c. of well-washed ether added, corked, and the mixture well shaken. As soon as the ether separates from the remainder of the fluid, the cork is removed and the wash-botlle arrangement, shown in Fig. 58, inserted. The lower end of the exit tube is now adjusted by sliding it in the cork so that it is just above the line of separation of the two fluids. The ether solution of the fat is now blown off into a weighed beaker or flask. Two more portions of ether of 10 c.c. each are added, shaken up, and blown off into the first portion. The ether is now distilled off and the fat dried in a water oven and weighed. The amount of fatso obtained represents that contained in 10 c.c. of milk, or in the amount weighed out. The results agree quite closely with the Adams method de- scribed below. 574 MEDICAL CHEMISTRY. Fig. s8. The total solids and water are determined by placing in a weighed platinum dish, a weighed quantity of the milk to be tested, say about 5 c.c. This is then placed upon a water bath and evaporated to dryness. Jt is now transferred to the water or air oven and dried at 100° C. until it ceases to lose weight. The loss in weight represents the water, the residue represents the total solids. Where great accuracy is unnecessary, the fat may be determined in the residue by treating it with warm ether and pouring this through a small filter, and repeating this pro- cess until the fat is completely dissolved out, which will require usually about 75 c.c. of ether. The ether is allowed to evaporate and the fat which remains behind is weighed, or the residue left in the dish may be again weighed, when the difference between this weight and the weight of the dry solids will give the amount of fat. The results in the fat are about 0.3 too low. The ash may now be determined by igniting the residue left after treatment with ether, at a dull red heat, until all the organic matter is burned off, weighing the residue, and calculating it as ash. For many purposes the fat may be calculated from the specific gravity and total solids. This is especially useful in the clinical ex- amination of human milk. It rests upon the assumption that every per cent, of milk solids not fat, raises the specific gravity by a definite amount, while every per cent, of fat lowers it by a definite amount.. An accurate determination of the specific gravity and total solids will, therefore, furnish the necessary dala for calculating the amount of fat. The formula by which the calculations are made is that of Hehner and Rich- mond. It is as follows : F. ^= 0.859 T. — 0.2186 G., in which F. = fat, T. := total solids, and G. ^ specific gravity, as ex- pressed in the third and fourth figures. Or, when the fat is known, the formula may be transposed so as to calculate the total solids, as follows : — .p_. F-f 0.2186 G. 0.859. The specific gravity must be determined with care, and for MILK. 575 rapidity only 5 c.c. of milk are evaporated to dryness to deter- mine the total solids. This may be conducted in a watch glass, using 2 or 3 c.c, if a platinum dish is not at hand. To illustrate the use of these formulae, let us assume in the examination of a given milk that the specific gravity, or G, was found to be 1030, that the total solids, on examination, gave 12 per cent. Substituting these figures in the above formula, we have : — Fat = .859 X 12 — -2186 X 30 = 3-75- Or if the fat has been determined, instead of the total solids, and found to be 3.75 per cent., then — Total solids = 3-75 + .^.86X3° ^ ,2. ■859 Another method has been proposed to calculate the solids not fats, from data afforded by the lactometer, specific gravity, and Feser's lactoscope, by means of the formula — — — , where G equals the specific gravity of the milk and A the remainder obtained on multiplying the per cent, of fat, as shown by the lactoscope, by .001 and deducting this from 1000. For example: Suppose in a given sample of milk the specific gravity, or G, is found to be 1030. The value of A in the above equation will be found by multiplying Ihe per cent of fat, 3.7, by .001, which will be equal to .0037, which, deducted from 1000, equals .997. Substituting 1030 for G, and this remainder, .997, for A in above equation, we have '°3° — -997 __ g of total solid. ^ .0037 ^ These short methods will be found useful in the examination of human milk, where long, tedious processes are not likely to be entered into. They are not to be mentioned as scientifically accurate, but are sufficiently so for clinical purposes and for the the use of sanitary inspectors in sorting milks. In the accurate estimation of the fat of milk the officially recognized method is that of Adams. Instead of drying the solids in the usual way, the milk is absorbed by bibulous paper previously thoroughly exhausted with ether and alcohol. This paper is usually cut in the shape of long strips, and these are rolled into a coil and put in a special apparatus known as an extractor and shown in Fig. 59. The coil is put into the chamber of the middle piece of the apparatus, which is then connected with a condenser as shown. Sufficient ether to fill this chamber is put into the flask below, which is gently warmed. The ether distils up into the condenser and runs back upon the coil, filling the chamber until it flows over through the siphon tube into the flask below. This is repeated until exhaustion is 576 MEDICAL CHEMISTRY. complete. The ether is finally distilled off, and the fat in the flask is dried and weighed. The results obtained by this method are about .3 per cent, higher than those obtained by the method above described, of evaporating in a platinum dish and treat- ment with ether. This has been adopted by official chemists, both in England and in this country, as the standard method of estimating fat. For the accurate estimation of fat in milk in well-equipped laboratories, it leaves little to be desired in the way of accuracy, but is a little difficult without these facilities. 913. Milk Standards. — For ordinary purposes Fig. 59. the estimation of the total solids, the fat and the ash, are considered sufficient to determine. the question of the adulterations usually met with in the market. The standards that have been fixed by law in a number of the States all refer to specific gravity, fat, and total solids. Prosecutions are, therefore, usually based on these data. To calculate the per cent, of pure milk in a mixture the following formula may be adopted, based upon the legal standard of the State of New York, viz.: 12 per cent, of milk solids, 3 per cent, of fat, and 9 per cent, of solids not fat. 9 : solids not fat : : 100 : x = milk used in making loo parts of the mixture. For other standards the first member of the equa- tion will be the legal percentage of solids not fat. When the solids not fat are less than 9 per cent., it indicates some form of falsification. Suppose, for example, the solids not fat in any given analysis was 8.1. Substituting this in the above proportion we have — 9 : 8.1 : : lOo: x^go or this sample of milk had been made from 90 per cent, of milk and 10 per cent, of water. If the milk is skimmed the percentage of fat removed can be ascertained by the following formula : — fXS-F=x in which S = solids not fat, and F = fat found. Suppose, for example, the fat in a given case be 2 per cent, and the solids not fat 8 per cent. Substituting these in the above equation we have — §X8-2=x=2 MILK. 577 That is, 2 per cent, of fat has been removed from this milk. 914. The Estimation of Sugar. — For ordinary purposes a sufficiently correct estimation of milk sugar can be made by exhausting the residue that remains after the extraction of the fat by the process above given with weak boiling alcohol. This dissolves the sugar and the soluble portion of the ash. The solution is filtered, evaporated to dryness in a platinum or porce- lain capsule, and weighed. The residue is then ignited and the ash weighed and deducted from the weight of sugar and ash, to obtain the amount of sugar. Lactose may also be estimated with Fehling's solution, after the coagulation and removal of the casein withacetic acid. 915. The Determination of Casein. — Casein and albumin are generally determined by difference. When the direct deter- mination is desired, they may be precipitated by tannin, the pre- cipitate dried and washed with a mixture of i part of alcohol to 3 of ether until the washings show no trace of tannin. The whole is then dried and weighed. The albuminoids can also be determined by the method of Ritthausen, who employs a solution of CuSO,, containing 6.5 grms. to the liter and a solution of alkali of the strength of 14.2 grms. of KOH, or 10.2 grms. of NaOH to the liter. The copper salt precipitates the albuminoids together with the fat. Twenty c.c. of milk are taken, diluted with water to 400 c.c. ; 10 c.c. of the copper solution is added with constant stirring until the coagulum settles and the supernatant liquid is clear. The alkali solution is now added until the liquid is neutral, and the contents of the beaker are filtered, using a dried and tared filter paper. The precipitate is 'all transferred to the filter. It is washed first with water, then with dilute alcohol, and finally with ether, until all fat is removed. The remaining precipitate is again washed with alcohol and dried at iio° C. (230° F.) and weighed. The bluish mass is burned, and the loss, after deducting the weight of the filter paper, is reckoned as albumin- oids. 916. Detection of Impure Water. — The addition of water to milk, if it be pure water, can be regarded as harmless to adults. It is rather a sophistication than a harmful adulteration. As the "water usually is well water, which may itself be impure, it becomes a matter of importance, because the water may carry with it germs of typhoid fever, cholera, or other diseases, and will impart to the milk injurious properties. To detect impure water 49 578 MEDICAL CHEMISTRY. in milk the following process may be used: The milk is coagu- lated with acetic acid and filtered. To a suitable quantity of the whey add equal parts of a solution of naphthylamin sulphate and a freshly prepared solution of sulphanylic acid in sulphuric acid. The test may be made in an ordinary test tube or in a cylinder. If the milk contains nitrates due to an impure water, a rose-red color will appear, varying in intensity with the amount of nitrites present and deepening on standing. The test is very delicate. The following may also be employed: loo c.c. of the milk is boiled with 1.5 c.c. of a 5 per cent, solution of CaCl, and fil- tered. A small portion of the filtrate is treated with HjSOi con- taining 2 per cent, diphenylamin. This mixture is then floated upon concentrated H^SO,, when, if nitrates or nitrites be present in the milk, a blue zone will appear at the line of contact of the two liquids. Or the above test may be applied as follows : One c.c. of a solution of diphenylamin in HjSOi is placed in a small porcelain dish and a few drops of the milk allowed to flow down the side into the acid. If the milk contains nitrites or nitrates, a blue color will appear at the line of separation be- tween the acid and the milk. This test is very delicate and will detect the presence of a very small quantity of impure water. Nitrites and nitrates are not found in milk, even if contained in the food of cows. 917. Condensed Milk. — Owing to the difficulty of keeping ordinary milk, several processes of preserving it by concentration have been employed. As early as 1837 Newton preserved milk by evaporating it in shallow pans at 50° C. (122° F.), during which time air was blown through the milk. From that time to the present, preserved or condensed milk has been an impor- tant article of commerce. When milk is simply evaporated without the addition of a preservative it is called condensed milk. This is also put into the market sometimes under the name of evaporated cream. This term is also applied to what properly should be termed preserved milk, or milk which has been condensed with cane sugar added. Preserved milk is much thicker in appearance than condensed. Milk is usually con- densed to about one-third its original volume, although the makers usually claim that it is condensed to one- fourth the original volume. Analyses of a large number of samples made at' various times in this country give the average as a little short of one- third. The addition of two parts of water to one of the con- densed milk should, therefore, produce a milk of the same degree THE URINE. 579 of richness as the whole milk before condensation. Analyses made by Cornwall, of the condensed milks found in the American market, showed the following- average : — Water 26.95 percent. Milk sugar 13.38 percent. Milk solids 34-36 " " Cane sugar, . . . 38.82 " " Casein and albumin, 9.25 " " Ash 1.92 " " Fat 9.69 " " Calculating from these results, he found that the condensation varied from 2.27 to 3.12 times, the average of all analyses being about 2. 74 times, or the milk was condensed to not quite one-third the original volume. Condensed milk is largely used as a nour- ishment for young infants. For this purpose it is usually diluted with about 9 to 12 parts of water. Meigs has shown that if i part of the best commercial sweetened condensed milk be mixed with 9 parts of water, the mixture somewhat closely resembles in composition that of human milk, with the exception that it is deficient in fat, and that this mixture, with a small portion of cream added, gave a milk of nearly the chemical composition of human milk. In digestibility, condensed milk is inferior to cow's nvlk or human milk. It is open to the objection above mentioned to sterilized milk. It is open to the additional objection that a large part of the sugar present, when sweetened milk is used, is cane sugar instead of lactose, the natural sugar of milk. Cane sugar more readily undergoes acid fermentation in the stomach or intestine of the infant than lactose. Infants fed exclusively upon condensed milk show a tendency to develop rickets, or a failure of the nourishment of the bony structures. As a result, the development of the teeth and the ability to walk are somewhat delayed. THE URINE. gi8. The urine is an excretory fluid thrown off by animals. It IS partially filtered from the blood by the kidneys, and partly elaborated by these organs from waste materials found in the blood. It is composed of a watery solution of certain inorganic salts and nitrogenous principles which are of no further use to the body. As will be seen from the table below, human urine is not a liquid of uniform composition, but subject to very con- siderable variations. These variations may be physiological, or they may be indicative of diseased conditions, and a knowledge of them is an essential to correct diagnosis of many diseases. 580 MEDICAL CHEMISTRY. 919. General Physical Properties. — Normal urine, when fresh, is a clear, amber-colored, transparent liquid, having a peculiar, aromatic, characteristic odor, a bitter, saline taste, a distinctly acid reaction, and a specific gravity of from 1018 to 1022. The average specific gravity is generally given as 1018 to 1020. When it is kept in a clean vessel and away from contact with air, it will undergo but slight changes in several days. Reaction. — Normal urine is faintly acid, and grows more acid for a few hours after being voided, due to the so-called " acid fermentation." During this period of acid fermenta- tion, there is frequently deposited a whitish or pinkish, or, at times reddish, sediment, due to the separation of the acid urate of sodium or to crystals of uric acid. This sediment disappears again on warming the solution. On standing still longer exposed to the air, the acidity begins to grow less and less, and at the same time an odor of ammonia begins to be developed, and finally the reaction changes from acid to neutral, and from neu- tral to alkaline, with a strong odor of ammonia and more or less odor of putridity. The rapidity with which these changes take place is dependent upon the condition of the secretion and temperature, taking place more rapidly in warm than^in cold temperatures. An abundance of mucus, which can usually be seen after a few hours as a light, flocculent cloud, settling near the bottom of the vessel containing the fluid, greatly hastens these fermentative changes. This is especially the case if the bladder or the kidneys are in a diseased condition. There is produced with the mucus, especially in diseased conditions of the bladder, a peculiar soluble ferment, which hastens the above changes. The reaction of urine is best tested by dropping a small piece of a red and a blue litmus paper into the solution. If both are found red after a few minutes, the reaction is acid. If both are blue, it is alkaline. If they remain unchanged, the reaction is said to be " amphotic." If the alkalinity is due to ammonium carbonate, the red paper on drying .and warming over a flame turns red again. If due to the fixed alkalies, it remains blue on drying and warming. The fermentation of urine is due to certain microorganisms, of which the torula ureae is the best known. Normal urine is free from these organisms when passed, but in certain, abnormal conditions it may undergo an alkaline fermentation while still in the bladder, and that apparently without the intervention of these organisms. It has been found that the fermentation may be THE URINE. 581 complete in presence of an amount of carbolic acid which is fatal to the development of microorganisms. It has been as- sumed that an enzyme is secreted with the thick mucous secre- tion of urinary catarrh, which possesses active hydrolytic powers on a solution of urea. As the urine becomes alkaline from the production of ammonium carbonate from urea, it becomes tur- bid and acquires a paler color. The turbidity is due to the pre- cipitation of the phosphates of calcium and magnesium, the oxalate of calcium, and microorganisms. The phosphate of calcium and ammonium-magnesium phosphate, which separates when the urine becomes alkaline, are generally called the earthy phosphates. The latter of the two is called the triple-phosphate and is found in nearly all alkaline urines. 920. Composition. — The urine is chiefly a solution of urea and certain organic and inorganic salts, holding in suspension epithelial cells and mucous. The composition will be found in the table at the end of this chapter, with the chief variations met with in diseased conditions and their significance. The urine, like the milk and other animal fluids, is not of constant com- position. It is influenced by the amount of water and other fluids taken, by the temperature of the skin, by the emotions, by the blood pressure, local or general, the amount of work done, the time of day, the age, sex, the influence of medicine, etc. 921. The quantity of urine passed in 24 hours varies consider- ably. The average daily quantity passed by a healthy adult is about from 1400 to 1600 CO., or about 50 fluid ounces. The quantity of total solids contained in this is about 60 grras., or 1000 grs., and about one-half of these solids is composed of urea. The variations in the quantity will be found in the table at the close of this chapter. 922. The Color and Transparency. — In health, the color is usually a light amber. In general, the greater the quantity the lighter the color; and vice versa, the smaller the quantity the higher the color. As the color deepens by concentration it becomes more reddish. The color, as well as the quantity, is subject to great variations, even in health. It may vary from almost as clear as water to a dark yellowish-red, according to the degree of concentration. After drinking large quantities of fluids the quantity is very much increased and the color is light. After severe sweating, or in abstinence from drinking, it becomes concentrated and darker in color. The normal color of the urine is due to several more or less closely allied pigments, the chief of which are urobilin and indican, or uroxanthin. 582 MEDICAL CHEMISTRY. These coloring matters are probably decomposed products of the biliary coloring matters. The abnormal coloring matters are chiefly those of the blood or bile, melanin, hemoglobin, and coloring matters due to medicinal substances and certain vege- tables. An excess of the normal pigments of the urine may be expected in febrile conditions, and in diseases in which the blood is undergoing rapid destruction. Urobilin, when it exists in ex- cessive quantities, colors the urine a dark brownish-red, even without concentration, and the foam of such a urine is a yellow or yellowish-brown color. There is a marked increase of uro- bilin in conditions where the hepatic cells fail to perform their proper function, that is, in the condition known as biliousness. In such cases the skin and other tissues may also show the pres- ence of the same yellow color. The Tests for Urobilin. — First. The spectroscopic ex- amination shows absorption bands in the green between the lines b and F. In order to. see these lines it is often best to dilute the urine by pouring water carefully upon the top of the heavier urine in the test tube. After allowing the liquids to remain at rest for a short time, examine the water above the urine for the absorption bands. Second. Chemically we may test for urobilin by the addition of ammonia to the urine, when, if much urobilin be present, it grad- ually assumes a greenish hue. It is then filtered and a watery solution of ZnClj added, when there appears a rose-red color with greenish fluorescence, due to urobilin. Indican occurs in normal urine, but it occurs in increased quantities when there is an accumulation of the intestinal con- tents, as in occlusion, in peritonitis, or obstinate constipation. It is here probably not due simply to the accumulation of the intestinal contents, but to putrid fermentation of the contents when too long retained. The presence, then, of an excess of indican is an index of the amount of intestinal putrefaction. Indican is always found in all forms of severe cachexia, as well as in Asiatic cholera. It is detected in increased amounts by the addition of an equal volume of strong nitro-hydrochloric acid, and dropping into this 2 or 3 drops of a concentrated solution of chlorinated soda. Immediately, or after a few seconds, there is formed just beneath the surface a bluish-black cloud of indigo. By stirring the chlorinated soda solution into the urine, we ob- tain, according to the quantity of indican present, a more or less dark coloration of the whole fluid. If we now shake the fluid with chloroform, the indigo is dissolved out by the chloroform. THE URINE. 583 and settles as a blue layer at the bottom. Care must be taken not to add too much of the chlorinated soda. Coloring matters of the bile and blood will be considered again. Certain medicines and vegetables may color the urine. Rhu- barb and senna color the urine a brownish color, but if alkaline, or if made alkaline, it becomes a purple-red. The coloring agent in this case is the chrysophanic acid found in these medi- cmes. After taking logwood the urine becomes reddish, or violet when made alkaline. Santonin colors it yellow or green- ish-yellow, which, on the addition of an alkali, changes to red. Picric acid also gives a yellow color, which does not change to red on the addition of an alkali. Phenolnaphthalin, creasote, preparations of tar, or arsine (AsH,), impart either a greenish or a greenish-black color to the urine. Brown or brownish-black urine is observed in patients with melanotic tumors. The color- ing matter in this case is due to melanin. 923. Transparency. — Normal urine is transparent, con- taining only a slight flocculent cloud of mucus, visible after standing a few minutes. If the urine is turbid when passed, it is pathological. It is usually turbid in all diseases of the urinary passages, from the excessive amount of mucous and epithelial elements, and because the urine in this condition readily under- goes alkaline fermentation in the bladder, when the earthy phosphates are precipitated as a white sediment. In fevers, the quantity of urine is occasionally so small that the urates separate even in the bladder, and especially is this the case in certain diseases of children where the oxidation is deficient, as in capillary bronchitis and pneumonia. Admixtures of blood, pus, and chyle make the urine turbid. The most striking turbidity is produced by the admixture of chyle, which gives a milky-white appearance. Here the milky appearance is due to an admixture with the urine of emulsified fat and imperfectly dissolved proteids. Many urines which are clear when passed, become turbid on standing, from the sei)aration of the acid urates of sodium or ammonium. The turbidity of alkaline urine has already been mentioned. 924. Specific Gravity. — It varies from 1015 to 1028, ac- cording to the degree of dilution or concentration. Pathological urines may vary from almost that of water to 1050. As a rule, the urine of Bright's disease is of low specific gravity, and in diabetes of high specific gravity. The specific gravity of urine 584 MEDICAL CHEMISTRY. is generally determined by the uririometer, which is a small hydrometer graduated to include the variations in specific gravity usually found in urine. (See page 13.) It is usually graduated so that only the last two figures of the specific gravity appear upon the stem, and so as to read correctly at 60° F. If the temperature is above 60° F., it will be sufficiently accurate for clinical purposes to add one degree in specific gravity for every ten degrees in temperature, i. e., if it read 1018 at 80° F., it would read 1020 at 60° F. The ordinary urinoraeters of the market are apt to be unreliable. It is best, therefore, to test the instrument by careful determinations of the specific gravity of solutions of common salt, with the specific gravity flask, and compare the readings of the urinometer with these determin- ations. The urinometer is used as follows : The urine is placed in the upright jar, or cylinder, wide enough to allow the instrument to float freely, and deep enough to float it. When it has come to rest, the surface of the fluid in the jar is brought to the level of the eye, and the reading taken at the lower edge of the meniscus formed by the upper surface of the urine. The mark on the instrument wh'ich is cut by this line, and which can be distinctly seen, is taken as the correct reading. If the urine be turbid, this method cannot be employed, as the reading will be more or less uncertain. 925. Total Solids. — As stated before, the normal amount of solids passed by an adult An twenty-four hours is about 60 grms., or 1000 grs. An approximate estimation of the total solids may be made by multiplying the last two figures of the specific gravity, carefully taken, by the factor 2.33, which will give the number of grms. of solid matter in 1000 c.c. of urine, from which it will be easy to calculate the amount in 24 hours. If, for example, the quantity in 24 hours be 1500 c.c, and the specific gravity 1020, the total solids would be 20 X 2.33 = 46.6 grms. of solids in 1000 c.c. In 1500 c.c. there will be 1.5 as much, or 69.9 grms. If it be desired to use English meas- ures, we may determine the total solids by multiplying the last two figures of the specific gravity by the number of fluid ounces passed. Thus, if the number of fluid ounces be 50, and the specific gravity 1020, then the total solids will be 50 X 20 ^ 1000 grs. These methods of calculating the total solids give only approximate results, but in most cases will be found suffi- ciently accurate for clinical purposes. THE URINE. 5S5 A more exact method for determining the total solids, is to evaporate 10 c.c. in a white porcelain dish aud dry in a water oven to constant weight. The difference between the weight of the dish and of the dish with the solids, will give the weight of the solids in 10 c.c. of urine. Even by this method there is some loss during the evaporation. 926. Odor. — The odor of normal urine has been described as aromatic. A putrid odor is due to the odor of products of decomposition. Occasionally the urine is putrid when passed, the putridity being due to the putrid fermentation of pus, albumin, or some other foreign matter mixed with the urine in the bladder. Sulphuretted hydrogen sometimes occurs in the urine, and a faecal odor is occasionally met with, indicating a fistulous opening between the bladder and the intestine, or from abscesses between the bladder and rectum. A number of sub- stances when taken internally, cause the urine to assume a characteristic odor. Many aromatic substances impart their odors, as oil of turpentine (giving the odor of violets), cubebs, copaiba, asparagus, garlic, valerian, etc. 927. Inorganic Constituents of the Urine. — The urine contains certain inorganic salts, which are especially the chlo- rides of potassium and sodium, the phosphates of potassium, sodium, magnesium, and calcium, and sulphates, or sulphuric ethers, of indol and skatol. These salts are generally tested for, by tests for the detection of the corresponding acids. 928. Chlorides. — For the detection of the chlorides add a few drops of nitric acid, and then a solution of silver nitrate (i to 10). The chloride of silver separates as a white, curdy pre- cipitate, which should occupy not more than one-fourth the volume of the urine taken. If the settled precipitate occupies much more or less than one-fourth the volume of the quantity of urine taken, the quantity is increased or diminished. It is always best, in making this test, to compare the specimen under examination with normal urine. In most cases this approximate estimation of the chlorides will be all that the clinician will demand. Occasionally, however, it becomes necess.-iry to make a more accurate determination. For this purpose it is necessary to have a decinormal solution of silver nitrate, t. e., a solution containing 16. 96 grms. of pure silver nitrate, dissolved in a liter of distilled water. ' Quantitative Estimation of Chlorides.— Dilute lo c.c. of the urine with about 50 c.c. of water and add a few drops of a rather strong solution of potas- sium chromate. Now drop the silver solution from a graduated burette (see 50 S86 MEDICAL CHEMISTRY. Fig. 60) drop by drop, until a permanent reddish color indicates tliat the chlorine has all been precipitated, and that the silver has begun to form silver chromate. i c.c. of silver solution represents 0.00354 grm. of chlorine, or .00584 grm. of NaCl. In Fig. 6a highly colored urines this method is sometimes inap- plicable, owing to ihe charge of color being masked by the color of the urine. In such cases it is best to use the follovfing method." Second Method. When to a solution of silver nitrate, acidulated with nitric acid, sulphocyanafe of ammonium or potassium is added, a white precipitate forms, which is insoluble in nitric acid. If the fluid contains a ferric salt, a blood-red color forms at the moment when the last of the silver is precipitated. Volhard's method of estimating the chlorides makes use of this principle. The following solutions are needed in the process, i. Pure nitric acid. 2. A strong solution of ferric alum (sulphate of iron and ammonia) free from chlo- rine. 3. A decinormal ni- trate of silver solution made by dissolving 16.96 grms. in a liter of distilled water. 4. A decinormal solution of potassium sulphocyanate or of ammonium tulphocyanate. This should be6f exactly the same strength as the silver solution. It is made by dis- solving 6.5 or 7 grms. of the sulphocyanate in about 400 c.c. of water. To standard- ize the sulphocyanate solu- tion a portion of it is put into a'burette and 10 c.c. of the decinormal silver nitrate solution brought into a beaker with a few drops of the solution of iron alum. The. mixture is well stirred and the sulphocyanate solution added drop by drop until a slight but permanent red color appears. In accordance with the result obtained the Graduated Burettb THE URINE. 587 sulphocyanate solution is diluted to such a point that 10 c.c. of it will just neutralize 10 c.c. of the AgNO,, solution. If, for example, 8 c.c. of the sulpho- cyanate produce a red color, we then know the amount of sulphocyanate in 8 c.c. is that which should be in 10 c.c. Therefore, we dilute the 8 c.c. with sufBcient amount of water to make it 10 c.c, or if we have 500 c.c. we shall add to every 8 c.c, 2 c.c. of water, or we make the calculation by the follow- ing proportion : — 8 : 10 : : 450 : x = 562.5, or 450 c.c. of the solution first made up will re- quire to be diluted to 562.5 c.c, or there must be added 12.5 c c of water. Having thus corrected this solution to make it agree in strength with that of the silver solution, we again compare them to see if it is correct. The process is conducted as follows: 10 c.c. of the urine is measured out with a pipette, and placed in a graduated flask of 100 c.c. capacity. Fifty c.c. of water are added, and then, successively, 4 c.c. of nitric acid and 10 c.c. of silver solution. The flask is closed with a glass stopper, and agitated until the precipitate ceases to form, and the fluid tends to clear. Distilled water is added to the 100 c.c. mark. A portion of the fluid is then passed through a dry filter, and when 50 c.c. have run through, a few drops of the iron alum solution is put in, and then the sulphocyanate solution run in until a red color appears. The amount of sulphocyanate solution added deducted from the amount of silver solution added, gives the amount of silver used up by the chlorine in ^ of the 10 c.c of urine, or 5 c.c. 929. Phosphates. — Phosphoric acid exists in the urine coiubined with the alkalies (about ^), and with lime and mag- nesium. These phosphates are, therefore, generally distinguished by the terms alkaline and earthy phosphates. The acidity of 'the urine is generally believed to be due to the acid sodium phosphate (NaHjPO^). Sodium phosphate (NajHPO,) is neutral in reaction, and NajPOi is alkaline. In acid urines we have NaH.,P04, Na^HPO^, CaHPO^, CaHj- (P0,)2, MgHPO,, while in alkaline urines we find in solution NajPOj, and as precipitates Ca3(P04)2, Mgj(P04)2, and MgNHi- By adding an alkali to normal urine the phosphates of calcium and magnesium, termed earthy phosphates, are precipitated. The phosphates of sodium and potassium remain in solution. The earthy phosphates may be approximately estimated by adding a few drops of ammonium hydroxide solution to the urine, and observing the amount of turbidity produced after boiling. By comparing this with the amount obtained by the same treatment of normal urine, it will indicate whether the quantity is excessive or deficient. The alkaline phosphates may be detected in the filtrate from the earthy phosphates, by the addition of a few drops of MgSO, solution and some NH^CI. This precipitate shotald be much more voluminous than that 588 MEDICAL CHEMISTRY. produced by the earthy phosphates, and whether in excess, normal, or deficient, may best be determined by comparison with normal urine. The quantitative estimation of the phos- phates is rarely required. 930. Sulphates. — The sulphates are detected by the addi- tion of BaClz in the presence of free HCl. It appears as a fine white precipitate of BaSOi, rendering the solution opaque, and milk-like in appearance. An approximate estimation may be made by comparing the turbidity with that of normal urine treated in the same way. An excess of sulphuric acid generally indicates an excess of putrefactive decomposition in the intes- tine, unless it should be due to the taking of an excessive amount of sulphates with food or drink. 931. Organic Constituents — Urea, CO(NH2)2. — Urea is the most important constituent of the urine, as it is the chief condition in which nitrogen leaves the body. It is by far the most abundant solid ingredient of the .urine. Its chemical properties have already been described. The qualitative detection of urea may be made by evaporat- ing a few drops of urine on a glass slide, moistening with nitric acid and allowing it to crystallize, and examining the crystals of urea nitrate, CO(NH2)2HN03, under a microscope of low power. The quantitative estimation of urea in urine is a matter of considerable importance, as it is generally looked upon as an index of the retrograde or destructive changes going on in the body, or of the eliminating power of the kidneys. The quantity of urea in 24 hours has been put down at from 30 to 33 grms., or from 430 to 550 grs. The quantity will be increased by the increased consumption of a nitrogenous diet, or by increased exercise, and it will be diminished by non-nitrogenous diet and by lessened exercise. In estimating what should be regarded as a normal amount of urea, the condition of the patient, as to exercise, appetite, and dietary, should be taken into account. Roughly, in the absence of sugar, albumin, and other abnormal ingredients, the urea may be regarded as one-half the total solids. The more accurate quantitative estimation requires so little time, apparatus and skill, that it is now generally employed. The determination is based upon the fact that urea is decomposed by alkaline hypochlorites or hypobromites into carbon dioxide, water and nitrogen. CO(NH2)2 -f- 3NaBiO = 3NaBr + COj H" 2U.fl + N^. U'HE URINE. 589 Fig. 61. n\ The liberated N escapes and may be collected and measured, while the other products of the reaction remain in solution. The hypoba-omite solution is prepared as follows : 100 grms. of NaOH are dissolved in 250 c.c. of water, and to this solution, when cold, 25 c.c. of bromine is added, and the solution kept cold. This solution contains sodium hypobromite, hydroxide, and bromate. The solution should be freshly prepared, as it readily undergoes decomposition. Owing to the unstaibility of this solution and the excessively disagreeable handling of bromine, the author employs a solution of sodiuna hypochlorite, or chlorinated soda, with the addition of KBr. This solution acts as well, by the method to be described, as the above. Various forms of apparatus have been devised for the quantitative estimation of urea. The simplest of these is the one devised by Dr. C. A. Doremus, which is represented in Fig. 61. The tube. A, is filled with the above-mentioned solution of hypobromite, and i c.c. of urine is introduced with the pipette, B, as nearly as pos- sible at the center of the lower portion of the up- right limb. The urea is decomposed and the N rises to the upper closed end. After the decom- position is complete, the urea is determined by reading the graduations at the surface of the column of liquid. This ureometer, according to the graduation, gives either the mgrms. of urea in i c.c. of urine, the per cent., or grs. per fluid ounce. The author uses a graduated tube closed at one end. The graduations indicate at once the number of grs. of urea in a fluid ounce of urine, when i c.c. is taken for the estimation. (See Fig. 62.) The process is conducted as follows: A 25-per-cent. solution of KBr is added to the fifth division. The chlorinated soda solution is then added to the fifteenth or twentieth division. The tube is now inclined and pure water poured carefully down the side of the tube and floated upon the top of the fluids already in. I c.c. of urine is then added, in the same inclined position, so that it will not mix with the reagents below, but remain in the water at the surface of the fluid. The open end of fhe tube is now quickly closed with the thumb, and the top firmly grasped in the right hand. The tube iS now inverted, and the contents well mixed. A rapid decomposition takes place, which is usually 59° MEDICAL CHEMISTRY. ended in from three to five minutes. During this time the liquid is kept agitated without violent shaking. As soon as the effer-i vescence has ceased, the reading is taken at the surface of the fluid, with the tube still held in the inverted position. It is now opened under water, when the column of fluid in the tube will fall, and the reading is taken again. It is best to have a wide, deep jar for the water, so that the tube may be depressed to bring the surface of the liquid in the tube to the surface of the water in the jar ; but an ordinary bowl may be used, as the error caused by the differ- ence of thre& or four inches of water is very slight. The difference in the two readings gives the number of grains of urea in a fluid ounce of urine. This quantity, multiplied by the number of fluid ounces passed in twenty-four hours, gives the amount of urea excreted in twenty-four hours, which should be not far from 500 grains. A less quan- tity than 350 grains in an adult, who is eat- ing the usual amount, should be regarded as pathological, and suspicious of nephritis, or deficient kidney excretion. 932. Uric Acid, CsHiNA. is a con- stituent of normal urine, sometimes occur- ring in the free state, but oftener in combi- nation with potassium, sodium, ammonium, and occasionally with calcium and magne- sium, usually called collectively urates. For the description of this acid see Part IV. Uric acid is soluble in 14,000 parts of cold water, and is, therefore, frequently met with as a sediment and is then detected by microscopical examination. In quantity it varies from .4 to .8 grm. (from 6 to 12 grs.) in 24 hours. Detection. — It is best recognized when in the free state by the microscope. The crystals, as seen with this instrument, are colored yellow or reddish, and appear in a variety of shapes, the most common being the "lozenge" or "whetstone" shape. They are 'sometimes large enough, to be seen with the naked eye, when they appear as minute, gari>et-colored grains adhering to the sides of the vessel or upon the bottom. Chemical Tests.— No. 1.— Murexid Teat.— Evaporate Fig. 62. V Ureometer THE URINE. 591 a portion of the urine to dryness in a porcelain dish upon a water bath. Moisten the residue with nitric acid, and after evaporating off the acid, moisten the residue with ammonium hydroxid. If uric acid be present, either in the free state or combined, the residue assumes a beautiful purple red color, due to the formation of murexid. The reaction is said to occur also with xanthin, hypoxanthin, tyrosin, and some other bodies. No. 2. Carbonate of Silver Test. — Render the urine decidedly alkaline with NajCOj or K2CO3, and moisten a filter paper with the liquid. Now touch the moistened paper with a solution of AgNOs. A distinct gray stain indicates the presence of uric acid. The quantitative estimation of uric acid is tedious aad difficuU. The usual method is to acidify the urine with HCI and set aside for 24 hours. At the end of that time the uric acid, which has been set free by the HCI, separates out, owing to its insolubility, and is found aihering to the sides and bottom of the vessel. It is collected on a weighed filter, washed thoroughly, and dried at 100° C. (212° F.), and weighed. The weight of the filter with its contents, minus the weight of the filter alone, gives the weight of the uric acid in the volume of urine taken. The acidity of the urine is nearly proportional to the amount of uric acid excreted. The total acidity of normal urine is equivalent to the acidity of 2 to 4 grms. of oxalic acid in 24 hours. The greater part of this acidity is due to the acid sodium phosphate produced by the reaction of uric acid upon NajPOj, and the rest is due to the organic acids, most likely lactic. The acidity may be estimated by a decinormal solution of sodium hydroxide. 25 c.c. of the urine is diluted withes c.c. of water in a beaker. Three drops of an alcoholic solution of phenolphthalin are added, and a decinormal alkali run in from a burette, until a slight pink color is produced. The urine must be fresh for this estimation. The acidity may be calculated as phosphoric acid, as acid sodium phosphate, or, as is frequently done, as oxalic acid. Each c.c. of the decinormal alkali is equivalent to 0.0049 g""™- of phosphoric acid, or 0.012 grm. (.1198 more exactly) of acid sodium phosphate, NaHjPOi, or 0.0063 "f oxalic acid. Each molecule of acid sodium phosphate, or each 120 parts, is the equivalent of one-half molecule, or 84 parts, of uric acid, as will be seen by the following reaction : — Na^PO, + 2CjHjNp,Hj = NaHqH^NPj + NaHjPO,. Hence, each c.c. of decinormal alkali is the equivalent of 0.0084 of uric acid. 592 MEDICAL CHEMISTRY. ABNORMAL CONSTITUENTS OF URINE. These are albumin, globulin, albumose, peptone, glucose, acetone, diacetic acid, bile-coloring matters and acids, blood, blood-coloring matters, pus, chyle, and abnormal sediments, such as casts, excessive amount of epithelium, mucus, etc. 933. Albumin. — Albumin is found in the urine at times with- out apparentdisturbanceofhealth. ■Usually,however,it is regarded as pathological, and is so often associated with the various inflam- matory diseases of the kidney, that its presence is often taken as evidence of some one of these diseases. It occurs principally in the form of serum albumin. It is coagulated in the urine by a temperature of from 73 to 75° C. (163.4 to 167° F.). In all cases, the urine should be clear before applying the tests for albumin. If not clear, it should be either settled and decanted or filtered. The tests for albumin usually depend upon its coagula- tion, and the formation of a turbidity in the solution. A few tests depend upon a change in color. The tests that are most satisfactory when applied to the urine, are as follows : — 1. Heat about 5 c.c. of the urine to boiling in a test-tube. It is then examined for even the slightest amount of turbidity. This turbidity, if present, will be due to albumin or earthy phosphates. Now add, slowly, a few drops of acetic or nitric acid. If the turbidity be due to the phosphates it disappears, while if it be due to albumin, it remains permanent. Care must be taken in the addition of the acid, after boiling, to note the effect after each drop is added, and to go on adding until there can be no doubt that the urine is distinctly acid. This test will show traces of albumin under the most favorable conditions. 2. The Contact Method. — Place 2 c.c. of pure HNO3 in a test-tube, and, inclining the tube to one side, pour the urine carefully down the side olF the tube so that it may float upon the acid. This is best done with a pipette, or by pouring the urine from one test-tube into another, holding both in a nearly hori- zontal position. If this be done carefully, there will be very little admixture of the two liquids. If albumin be present, a white, opaque zone of coagulated albumin appears at the line of contact of the two fluids. A brown zone will frequently be seen at this point, which grows in intensity on standing, and is due to the action of the acid on the coloring matters, but it does not give any turbidity unless albumin is present. If bile be present. ABNORMAL CONSTITUENTS OF URINE. 593 the color may be green ; if blood, brown-red. This test is de- cidedly more delicate than No. i. Precautions. — Occasionally after the administration of tur- pentine, or balsams and resins, these are precipitated by HNO3 as a yellow-white cloud, which, however, is soluble in alcohol. I have never seen the uric acid, sometimes set free by HNO3, to even resemble the precipitated albumin so as to give any possi- bility of a mistake. Roberts modifies this test by using, instead of pure nitric acid, a mixture of one volume of HNO3 and five volumes of a saturated solution of MgSOi. This reagent is as sensitive as HNO3, and pleasanter to handle. It is used in the same way. 3. Acidulate the urine with acetic acid, filter if much mucin is precipitated, and then add a few c.c. of a solution of potas- sium ferrocyanide. Or, better, float the acidulated urine over the K^FtCys solution. If albumin be present, it appears as a white precipitate. This reagent does not precipitate peptone, mucin, or alkaloids. It is a very delicate and reliable test. 4. A cold, saturated solution of picric acid may be used by the cont;act method. At the line of contact, the albumin appears as a white zone. No previous acidulation of the urine is usually required. Some prefer, however, to add acetic acid to insure decided acidity. Heat afterward to dissolve alkaloids, mucin, peptones, and urates, which are precipitated with the albu- min. It is better to heat the urine before adding the test solution. 5. Sodium Tungstate Solution. — Reagent: Made by mixing equal parts of cold saturated solution of sodium tungs- tate and citric acid. As its specific gravity is heavier than that of urine, it is best applied by the contact method. This is an extremely delicate test, and precipitates at the same time pep- tones, mucin, some alkaloids, and urates, which are dissolved by heatiner. 6. Tanret's Test. — Potassio-mercuric Iodide Test. — : Reagent prepared as follows: Mercuric chloride 1.35 grms., potassium iodide 3.32 grms., acetic acid 20 c.c, distilled water 80 c.c. ; the HgClj and KI are separately dissolved in water and then united, and the acetic acid afterward added. The result- ing liquid is heavier than urine (specific gravity 1040) and is best used by the contact method. It is exceedingly delicate, detecting I part of albumin in 20,000 parts of urine. Heat to dissolve the alkaloids, mucin, and peptone, as in tests 4 and 5. 7. Acidulated Brine Test. — Reagent: To a pint of a saturated solution of common salt add one ounce of HCl and 594 MEDICAL CHEMISTRY. filter if necessary. This is a delicate test for albumin when properly used. It has a high specific gravity and is best used as follows : The solution is heated to boiling and the urine added by the contact method. If albumin be present, it appears as a zone at the contact surface. It does not precipitate peptone, albumose, or the alkaloids. 8. Trichloracetic Acid. — This is a white crystalline acid, sometimes employed as a test for albumin. It may be used in the form of a saturated solution, by the contact method, or the crystals may be added directly to the urine, when they will form a strong solution at the bottom of the tube. It presents no decided advantages over the tests above mentioned. 9. A solution of salicyl-sulphonic acid in water is a very delicate test for all forms of albumin, and is to be recommended because it does not precipitate peptone, mucin, or alkaloids. It is a white, crystalline compound formed by saturating strong H2SO4 with salicylic acid, and setting aside to crystallize. Metaphosphoric, or glacial phosphoric acid, has also been recommended by some as a reliable test for albumin in urine. Albumin test papers, suggested by Dr. Oliver, may be prepared by saturating bibulous paper in solutions of potassio- mercuric iodide, of potassium ferrocyanide, and of citric acid. To use these papers the urine is acidified with one of the citric acid papers, and then either a potassio-mercuric iodide, or a potassium ferrocyanide paper added. The quantitative estimation of albumin is of considerable importance, but somewhat difficult to perform. Comparative tests are all that the clinician will usually find necessary. The easiest approximate method, is to boil a given quantity of the urine in a test tube, add 2 or 3 drops of nitric acid, set aside for 12 hours, and note the volume occupied by the precipitated albumin. This is generally spoken of as volume per cent., and has no relation to actual percentage. A more accurate method, and one sufficiently so for clinical purposes, is with Esbach's albuminometer. This consists of a graduated glass tube, shown in Fig. 63. To use the instrument, fill to U with urine, and to R with the test liquid. Close the tube by a rubber stopper, mix by agitation, and set aside for 24 hours. Each of the main divisions which the precipitate covers, represents i grra. of albumin in i liter of urine. Test solution : Picric acid, 10 grms. Citric acid, 20 grms. Water 1000 grms. ABNORMAL CONSTITUENTS OF URINE. 595 Densitnetric Method. — Take the specific gravity as accu- rately as possible, noting the temperature. Coagulate the albumin, by boiling with the least amount of acetic ^'°- ^3- acid that will completely do this. Filter from albumin. Bring filtrate to the same temperature as before -and take the specific gravity again. The difference in specific gravity degrees multiplied by 0.4 gives the grams in 100 CO. of urine. Or, a difference of one degree in sp. gr.. gives 0.400 grm. albumin in 100. c.c. of the urine. It will be seen, therefore, that the specific gravity should be very accurately taken with the picnometer. 934. Serum Globulin, or paraglobulin, is usually associated with serum albumin, from which it may be sep- arated. It may be detected in the urine as follows : To a large volume of water in a beaker or urine glass let fall a few drops of albuminous urine. If globulin be present, each drop as it falls will be followed by a milky train, which, when enough is added, forms an opalescent cloud in the water. The addition of acetic acid dissolves this cloud. This test depends upon the fact that globulin is soluble in a weak solution of sodium chloride, but on greatly diluting this solution, the globulin becomes insoluble, as in pure water. It is, therefore, precipitated by diluting the urine until the specific gravity is 1002 to 1003. It may be precipitated by rendering the urine slightly alkaline with NHjOH, filtering to separate the phosphates, and adding to the filtrate an equal volume of a saturated solution of ammo- nium sulphate. If a precipitate forms, it is globulin. It occurs with serum albumin, and rarely without it. It is most abundant in lardaceous kidney, in some cases of acute nephritis, and in the temporary albuminuria of disordered digestion. 935. Albumoses, or Propeptones. — To test for albumose it IS best to first remove the albumin. This is best done by acidifying the urine with a few drops of acetic acid, and adding about one-third its volume of a strong solution of common salt, boiling, and filtering. Albumin and globulin are thus removed. The filtrate is allowed to cool, and any turbidity which separates on cooling, or after the further addition of salt solution, and which disappears by heating to re-appear again on cooling, is albumose or propeptone. Or, after the removal of the albumin and globulin as above, the solution may be saturated with am- monium sulphate, when albumose, if present, will be precipi- 596 MEDICAL CHEMISTRY. tated. The only disease with which it appears to be associated is osteomalacia. 936. Peptone. — Peptone is not present in normal urine, but is occasionally found, either with or without albumin. Peptone differs from albumin and albumoses.in that it is not precipitated by tests Nos. i, 2, 3, 7, and 8,- but is precipitated by Nos. 4, 5, and 6, and by tannin, phospho-tungstic acid,* and Millon's re- agent. When precipitated by tests 4, 5, and 6, it is dissolved when the solution is warmed, and separates again as it cools. Peptone gives with the biuret reaction a rose-red color, while albumin gives a purple or blue. Tests for Peptone. — These all require previous treatnnent of the urine. If albumin be present, it should first be removed, either by saturation with ammonium sulphate and filtration, or by the addition of acetic acid and potassium ferrocyanide and filtering. It is usually desirable to decolorize the urine by the addition of a solution of lead acetate as long as it produces a precipitate, and filtering. The test may now be applied to this filtrate. Phospho-tungslic acid, acidulated with acetic acid, added to this filtrate, will precipitate peptone, if present. But if it be present in small quantities, the cloudiness appears only after 5 to 10 minutes. A less sensitive test than the above is made by floating the urine upon some Fehling's test solution. At the point of con- tact a delicate rose-red zone will indicate peptone. When positive this test is valuable, but when negative it will not prove the absence of peptone. The significance of peptone in the urine, although not posi- tively settled, is believed to be due in most cases to disintegra- tion of pus corpusles somewhere in the body, and the absorption of the decomposition products. It is found in many of the acute fevers and in many acute inflammatory processes. It may serve to tell whether a pleuritic effusion is purulent or not, and to distinguish tubercular from epidemic cerebro-spinal menin- gitis, as the latter is usually attended with peptonuria, while t"he former is not. 937. Mucin. — Mucin is secreted by the healthy mucous membranes. It cannot be regarded, therefore, as abnormal in * Phospho-tungstic acid is made by adding HjPOjto a hot solution of sodium tungstate till decidedly acid. Cool, and render strongly acid with acetic acid. Filler after standing over night. ABNORMAL CONSTITUENTS OF URINE. 597 the urine until it is present in increased amount, and then it indicates an irritated or inflamed condition of the membranes of the urinary tract. It is not precipitated from its solutions by boiling, but is precipitated by alcohol, dilute mineral acids, acetic, picric, and citric acids. It is best detected by its form- ing a sediment on standing, which floats as a translucent cloud near the bottom of the containing vessel, but not upon it. It may also be detected by floating the urine upon a solution of citric or acetic acid, when just above the line of contact a some- what indefinite zone or coagulum gradually makes its appear- ance. Albumin, when present, is not precipitated by these acids without the application of heat. We may also precipitate mucin by the addition of about two parts alcohol to one part of urine, when mucin and any albumi- noid bodies present will precipitate. The precipitate may be filtered out, washed with alcohol, and the mucin dissolved out with warm water, when it may be precipitated from the filtrate again with alcohol or the dilute acids. 938. Accidental Albuminuria. — Whenever the urine con- tains blood, pus, or serous discharges it will of necessity contain albumin. Fibrin will be found when there are hemorrhages from the genito-urinary passages, and in intense or acute inflam- mations of the kidneys. It also occurs in the urine of most cases of chyluria. It is readily recognized by its spontaneous coagulation, forming a thick, gelatinous, glairy mass, separating at the bottom of the containing vessel. These coagula may be filtered out and their solubility determined. If insoluble in dilute alkalies and lo per cent. NaCl solution, it is fibrin. 939. Blood. — The presence of blood may be detected most readily and certainly by the microscope, when the red blood cor- puscles may readily be seen. Chemically, blood coloring matter can be detected by the use of the following test : Mix a small portion of the urine in a test tube with an equal volume of a mixture of freshly prepared tincture guaiacura and spirits of turpentine. The turpentine should previously have been exposed to the air for some time. If blood-coloring matter be present, the mixture assumes an in- digo blue color, whose rapidity of formation and depth of color depend upon the amount of blood-coloring matter present. Pus frequently, if not always, gives the same test. Saliva and salts of iodme also give a blue color with this test, but the color due to these substances appears only after a considerable lapse of time, and is seldom likely to mislead. From the depth of color of the 598 ' MEDICAL CHEMISTRY. urine, and the rapidity of the appearance of the blue color, one can judge of the relative atnount of blood in solution. The spirits of turpentine used in this test may be replaced by a solu- tion of peroxide of hydrogen, or a mixture of ether and H2O2 (ozonic ether). Having determined that blood is present in the urine, it is a difficult matter to decide whelher the albuminuria is due entirely to the albumin introduced with the blood, or whether it is a true albuminuria of renal or inflammatory origin. This will often depend upon other symptoms than those to be found in the urine. Dissolved blood-coloring matter is sometimes met with in the urine, when it is called hemoglobinuria. In hemoglobinuria, blood corpuscles are not to be found with the microscope, while in haematuria the corpuscles are found. It occasionally happens that the urine rapidly becomes alkaline after being secreted, and the red blood corpuscles are disintegrated and dissolved by the alkaline urine. The urine containing the dissolved corpuscles is then always alkaline, while the urine of true hemoglobinuria is usually acid. We may conveniently distinguish, then, two conditions: In one, the blood color- ing matter is in solution, and in the other it is in suspension as blood corpus- cles. In the former case the coloring matter will not separate on standing, while in the latter, there will usually separate within a few hours, a more or less abundant red sediment. If the hemorrhage be a profuse one, especially if from the bladder or ureters, the blood will almost all of it settle to the bottom of the containing vessel, and leave a clear yellow, almost normal-looking urine above ; while if the hemorrhage be a gradual oozing in acute inflammation of the kidneyi the coloring matter will remain in su.spension and the liquid retain its color for many days. If we add an alkali to urine containing blood, the earthy phos- phates are precipitated, carrying down with them the blood- coloring niatter and forming a blood-red deposit. By the appli- cation of heat the sediment deposits more rapidly. If the urine is already alkaline, and the phosphates have separated out, we can produce a precipitate for the purpose of carrying down the blood-coloring matter, by the addition of a few drops of a solu- tion of MgSOi. Hsemin crystals may be prepared from this precipitate, by spreading a small portion of it upon a glass slide and treating it with a crystal of common salt and a drop or two of glacial acetic acid, covering with a cover-glass, warming it gently, and examining, after a few hours, with the microscope. The crystals appear as small, oblique plates of a dark red or brown color. They are easily recognizable by a good one-quarter inch lens. 940. Pus. — If the urine contains pus it will always be turbid' to the naked eye, and rapidly deposit a white or greenish-white sediment. The clear solution will be found to contain albumin and globulin. The application of heat to the sediment does not ABNORMAL CONSTITUENTS OF URINE. 599 dissipate it, as it does the sediment of urates. Neither is it dis- solved by dilute acids, as is the somewhat similar looking pre- cipitate of the earthy phosphates. A whitish sediment, there- fore, which is insoluble by heat or dilute acids, and which dissolves in strongly alkaline solutions, giving a gelatinous, ropy liquid is probably pus (Donn6's test). When pus is treated with a solution of hydrogen peroxide it undergoes rapid effer- vescence. This is a valuable test for pus in the urine or ii) other fluids. The microscope is a more certain test for pus. Having detected pus in the urine, it is sometimes very difficult to determine whether the albuminuria accompanying it is acci- dental, i. e., whether the albumin is derived from the pus, or whether there is a true albuminuria due to some disease of the kidney. The symptoms of the patient will, in many cases, assist in determining, though not always. 941. Sugar. — It has been claimed by many that glucose occurs in normal urine, and it has been disputed by equally good authority. The most delicate tests do detect glucose in most urines otherwise normal, though not in all. Suffice it to say that the usual tests and those here mentioned, except Mo- lisch's, will not detect this substance in normal urine. Its appearance, then, in sufficient quantities to be detected by any of them must be regarded as abnormal. When glucose occurs in the urine in an appreciable amount, it is known as glycosuria. When its occurrence persists for a considerable time and in considerable amount, and is attended with an increased amount of a light-colored urine, generally of high specific gravity, it is pathological, and the disease is known as diabetes mellitus. The specific gravity is of some guide to the detection of diabetes mellitus, but the specific gravity alone is not conclusive. A high specific gravity with a large quantity of light-colored urine, is strong presumptive evidence of diahetes mellitus. The finding of sugar in such a case is confirmatory. The detection of sugar in the urine is a com- paratively simple process. Tests for Glucose. — Trommer's Test. — To 4 or 5 c.c. of urine in a test-tube, add one-half its volume of liquor sodae or liquor potassae, and i or 2 drops of a solution of CuSO^ (i to 10). If sugar be present a clear, deep blue color is obtained. If excess of copper sulphate be added, a clear solution may not be obtained, and will, in this way, disturb the test. The solu- tion is now to be heated almost to boiling, but it is better not to boil. If sugar be present, at first a greenish, and then a 6oo MEDICAL CHEMISTRY. yellow turbidity forms, which rapidly changes to a reddish- yellow color and precipitates red cuprous oxide. A flocculent precipitate of the earthy phosphates always forms on adding the alkali, and must not be mistaken for suboxide of copper. Urine containing an abundance of uric acid and mucus, and other substances found in some urines, will decolorize the blue solution, but there will be no red precipitate. In fever urines, this decolor- ization without precipitation, interferes greatly with the employ- ment of this test. It is, therefore, not to be relied upon in doubtful cases. 2. Other Forms of the Copper Test. — Haines' solu- tion is made by dissolving copper sulphate in a mixture of equal quantities of glycerin and water. This solution may be used in larger quantities than the aqueous solution of copper used in Trommer's test, and some of the difficulties of that test overcome. The decolorizing effect of normal urine is not sufficient to de- colorize a large amount of copper solution. By adding a con- siderable amount of Haines' solution before heating, this error is partially eliminated. Fehling's solution is sometimes em- ployed as a qualitative test, but usually only as a quantitative test ; Haines' solution has all the advantages of Fehling's with the additional advantage that it keeps well. 3. Bismuth Test. — To a few c.c. of the urine in a test-tube add an equal volume of sodium hydroxid, and then a fragment of bismuth subnitrate ; mix well and boil for three to five minutes. If sugar be preseiit, black metallic bismuth will be deposited as a sediment. If the quantity of sugar be small, only a part of the bismuth will be reduced, and the precipitate will appear gray.; Albumin must be removed before this test is applied, or it will be decomposed by boiling with the alkali, forming the sulphide of bismuth, which will give a black precipitate. 4. A better form of this test is as follows : A solution is made of bismuth subnitrate, 2 grms. ; Rochelle salt, 4 g^ms. ; sodium hydroxid, 8 grms.; and distilled water, too c.c. The urine is heated to boiling, and a few drops of this alkaline solu- tion of bismuth added, and on continuing the boiling, if sugar is present the mixture turns black. As in the previous test, albumin must be absent before this test is applied. This reagent is exceedingly delicate, and it is claimed to detect .025 per cent, of glucose. 5. Picric Acid Test. — To about 5 c.c. of urine add one- half as much of picric acid solution (as in testing for albumin), and then 2 c.c. of liquor potassas or liquor sods, and boil. If ABNORMAL CONSTITUENTS OF URINE. 6oi sugar is present, a dark mahogany-red color is developed. If no sugar be present, a dark hue is developed before boiling, but not the dark color above described. If albumin is present, a tur- bidity will form on the addition of the picric acid, but it does not interfere with the test. 6. Moore's Test. — Add to the suspected urine one-half its volume of liquor sodse, and boil. If sugar is present, a dark- yellow, brown, or chocolate color is produced. The depth of color is proportional to the amount of sugar present. 7. Indigo-carmine Test. — Reagent: Mix one part of dried commercial extract of indigo with 30 parts of pure dry sodium carbonate. To 5 c.c. of the suspected urine, add enough of the above powder to give a transparent, blue solution, and heat to boiling. If sugar is present, the solution changes to violet, cherry-red, and finally yellow. On agitation, these colors appear in the reversed order. Instead of extract of indigo, a solution of sulphate of indigo with excess of sodium carbonate may be employed. None of the ordinary constituents of the urine affect this test, while all the acids of the urine affect Fehling's solutions; and many other substances which reduce the copper test do not affect the indigo-carmine test. In careful hands it is very much to be recommended as a sensitive and reliable test for glucose in the urine. 8. Phenylhydrazin Test. — For the details of this test see glucose in part V of this book. 9. Alphanapthol Test. — Molisch's Test. — To i c.c. of the urine add 2 c.c. of a saturated solution of a naphthol, and after mixing, add excess of H2SO4. If suga/ be present, a deep violet color is developed. On dilution with water a blue pre- cipitate occurs, which is soluble in alcohol, ether, and potassium hydroxide to give a yellow solution. If instead of naphthol we use thymol or menthol, a deep red color is produced which gives a carmine-red flocculent precipitate on dilution, which dissolves as above with the formation of a yellow solution. This test is exceedingly delicate and reacts with most sugars and glucosides. Urea, indican, creatinin, xanthin, uric acid, hippuric acid, phenol, pyrocatechin give negative results. Nor- mal urine, however, generally responds to this test, and Molisch, therefore, concludes that it contains sugar. The Quantitative Estimation of Glucose. — This is' generally made with Fehling's solution. This solution is best prepared in two parts, which are to be kept separately, as the 5' 602 MEDICAL CHEMISTRY. completed solution does not keep well. These solutions are pre- pared as follows: No. i. 34.639 grms. of pure recrystallized copper sulphate is dissolved in distilled water and made up to exactly 500 c.c. No. 2. 175 grms. of crystallized Rochelle salt and 60 grms. of sodium hydroxide are dissolved in distilled water and made up to exactly 500 c.c. When needed for use, exactly equal volumes of these two solutions are mixed. The solution will be of such strength that 10 c.c. is decolorized by .050 grm. of glucose or diabetic sugar. The process is conducted as follows: 10 c.c. of Fehling's solution are measured out into a beaker or porcelain basin, diluted with about 40 c.c. of water, and brought to the boiling point. The urine is delivered into this blue solution from a burette, until the blue color is just discharged. The amount of urine added will then be read off from the burette, and this amount will contain .050 grni. of sugar. From this it will be easy to calculate the quantity contained in 100 c.c. or a liter. If the urine contains a considerable quantity of sugar, it will be necessary to dilute it with four volumes of water before beginning the titration. It is always somewhat difficult to determine the exact disappearance of the blue color, owing to the presence in the solution of the precipitated suboxide of copper. This difficulty may be overcome by the addition of some substance that will prevent the precipitation of the cuprous oxide as NH^-' OH,KCy or K^Fe (CN)e. The author's method is as follows: Ten c.c. of Fehling's solution are measured out into a suitable flask. To this 10 c.c. of a freshly prepared 10 per cent, solution of potassiiim ferro- cyanide is added, ajid about 30 c.c. of water. The mixture is heated on a water-bath and the urine, previously diluted with water, if it contains much sugar, is run in from a burette, drop by drop, until the blue color just disappears, which can readily be seen, as the solution remains clear to the end of the reaction. The addition of the slightest excess of sugar shows itself by the solution becoming quickly brown. By careful comparative tests the author has found this method to be accurate, reliable, and rapid, provided the solution be not boiled during the reduction. The. best temperature for the process was found to be between 80° and 90° C. (176° to 194° F.). Estimation by the Polariscope. — This is the most con- 'venient and quickest method for the determination of glucose when the quantity exceeds i per cent., and when all appliances are at hand, which is seldom the case except in well-equipped ABNORMAL CONSTITUENTS OF URINE. 603 laboratories. The method, briefly, is as follows : The suspected urine, freed from albumin, is treated with a solution of basic lead acetate, in the proportion of i to lo of the urine, and filtered. The tube of the polariscope is filled with this fluid, when it is placed in position and the rotation determined. The readings must be increased by one-tenth (allowance for the lead acetate solution). The specific rotatory power of glucose is + S2-5°- The weight of the sugar in the solution will be given by the formula : W =i — ^---,. In which a = observed rotation, 1 the 52-5 X 1 . . ■ ' . length of the tube in decimeters, and W the weight of sugar in I c.c. of the solution. Suppose, in a given case, the rotation observed was 4°, after allowing for the lead solution, and the length of the observation tube was two decimeters. We will then have W = — - — , or 52-5 X 2 — = .038 grm. in i c.c. of urine, or 3.8 per cent. As Iffivulose sometimes occurs with glucose in cases of dia- betes, and as it will rotate the plane of polarized light to the left instead of to the right, and, in fact, as there are a number of substances likely to occur in the urine which rotate the plane of polarized light, this method of determining sugar is not always free from error. Lactose or milk sugar, occurs in the urine of nursing women or of women soon after weaning. Its recognition requires first its'separation from the fluid. Dextrin has been found in the urine. of diabetics, where it seems to take the place of glucose. Other carbohydrates found rarely in the urine are inosite, maltose, and animal gum. 942. Acetonuria. — Normal urine contains traces of acetone, but it occurs in excessive quantities as a pathological condition. It is found in many of the fevers, certain forms of cancer, in starvation, and in certain nervous troubles accompanying diabetes. The commonest of these is febrile acetonuria. Its appearance in diabetes indicates an advanced stage of the disease. Detection. — Four or five c.c. of the urine is treated virith a few drops of a freshly made solution of sodium nitroprusside and with a strong solution of NaOH. The red color "produced, which rapidly disappears if acetone be present, gives place to a purple or violet color on the addition of acetic acid. For a more accurate test it is necessary to distil the urine and apply the following test to the distillate : — Lieben's Test. — To several c.c. of the distillate add a few drops of a solu- tion of iodine in jjotassium iodide, and then a solution of KOH. If merely a trace of acetone be present, a precipitate of iodoform crystals is deposited. This test is reliable and delicate in the absence of lactic acid and alcohol. 6o4 MEDICAL CHEMISTRY. 943. Diacetic Acid appears in the urine of diabetics and certain fevers, and is always an abnormal constituent. It is most common in the contagious fevers of childhood, and in such cases has little significance; but in adults it is a grave symptom, as it usually precedes the advent of coma. It usually occurs together with acetone, and in the presence of ferric chloride produces a wine-red color, which is not entirely characteristic, because other substances produce the same color. The following process will serve for its detection : A fairly strong solution of ferric chloride is cautiously added to the urine, and if a phosphate precipitates, this is removed by filtration, and more Fc2Clg added to the filtrate. if a red color appears it is divided into two portions. One portion is boiled, whilst the other is treated with H^SQ^, and extracted by shaking with ether. If the urine which has been boiled shows little or no change, while the FejCl^ reaction in the ethereal extract is not evident after twenty-four hours, and if at the same time it is found to be rich in acetone, diaceturia may be inferred. Usually, if the reaction with ferric chloiide is very marked, and no acetone is discovered to be present, we m.iy conclude that diacetic acid is present, with- out the above somewhat tedious test. The urine for this test must be fresh, as diacetic acid is rapidly converted into acetone on standing. Acetone is an oxidation product of diacetic acid. If the quantity of acetone be large it may cause toxic symptoms. Ozybutyric Acid is found in the blood of diabetic patients, and its oxida- tion produces diacetic acid. The relation of these three bodies are then oxy- butyric acid, diacetic acid, and acetone, in the order named. 944. Lipaciduria is a term which has been applied to the condition in which volatile fatty acids are found in the urine. These occur in traces nor- mally, especially formic, acetic, and butyric acids. As a symptom of disease, however, they are often present in quantity ; .thus, in the urine of fevers, in certain diseases of the liver, and in diabetes, formic, acetic, propionic, and butyric acids have been detected. For their detection the urine is distilled with phosphoric acid, and the test applied to the distillate. For simpler tests we may apply the following : Acetic acid may be detected by the odor of acetic ether when the urine is warmed with alcohol and sulphuric acid. Ferric chlo- ride gives a red tint, which disappears on boiling if acetic acid is present. Formic acid gives a while precipitate with silver nitrate, which blackens on warming. 945. Fat. — Fat occasionally occurs in the urine and gives to it a more or less turbid appearance, which clears on shaking the solution with ether. On separating and evaporating the ether, the fat globules remain behind. In chyluriawe have an opacity due to fat and albuminous substances in imperfect solution. In some cases the appearance of this urine is intermittent, appear- ing only at certain times of the day, in others it is constant. In some cases chylous urine deposits a spontaneous clot of fibrin, while in others it does not. The fat may be separated by extrac- tion with ether, but the turbidity may still remain. In some cases, however, the turbidity disappears with the extraction of the fat. Detection. — Its detection is usually sufificiently e^sy from ABNORMAL CONSTITUENTS OF URINE. 605 the milky-white color and the separation of the fat on standing. Microscopically, the fat globules can be detected in some cases, l}ut in others the microscope fails to reveal them. The author has seen a case where they were not visible with a one-sixteenth inch objective. 946. Bile. — Urine containing bile usually has an abnormal color — either a brilliant yellow, a greenish-yellow, or brown. When the bile is abundantly present, the froth or foam produced on shaking the urine is quite permanent, and is more or less col- ored. A piece of filter paper or linen moistened with such urine retains the yellow color on drying. Gtnelin's Test. — Upon i or 2 c.c. of a partially decomposed yellow nitric acid, in a test tube, carefully float 4 or 5 c.c. of the suspected urine. If bile-coloring matters be present, succes- sive colors will appear in the urine, beginning with green, then passing through blue, violet, "red, and yellow, the green appear- ing at the top and the others in the order named downward. The green color is always present when bile is present, but the reddish-violet color must not always be taken for evidence of bile, as the normal coloring matters may produce such a coloration. If the decomposed nitric acid, or nitrous acid, be not at hand, it may readily be prepared by adding a fragment of zinc to ordi- nary pure nitric acid. This test may also be applied as follows: The urine may be mixed with a concentrated solution of sodium nitrate, and the mixture floated upon sulphuric acid, when a play of colors will be obtained as before. Ultzmann's Test. — To 5 c.c. of the urine add 2 c.c. of a strong solution of KOH (i 103); mix well and add excess of pure hydrochloric acid. The mixture will assume an emerald- green color if bile-coloring matters be present. Tincture of Iodine Test. — Upon the surface of the urine in a test tube float a few drops of tincture of iodine. At the Ime of contact of the two fluids, there appears after a few min- utes a beautiful emerald-green zone when biliary coloring matters are present. This test seems to be delicate and reliable. Biliary Acids. — While the acids usually occur in the urine of jaundiced patients along with the coloring matters, their de- tection is not so easy. Pettenkofer's test can be applied here only after evaporation to dryness, the solution of the biliary salts in alcohol, evaporating the alcohol, dissolving the residue in water, and the application of the test to this solution. Dr. Oliver's peptone test is, however, applicable to urine. The reagent is prepared as follows : Pulverized peptone (Savory and 6o6 MEDICAL CHEMISTRY. Moore), 2 grms. ; salicylic acid, 0.250 grm. ; acetic acid, 2c.c.; distilled water, sufficient to make 250 c.c. The. urine, rendered perfectly clear by filtration, is rendered acid and diluted until the specific gravity is 1008. One c.c. of this urine is run into about 4 c.c. of the above test solution. If biliary salts are present, a distinct milkiness promptly appears, but it becomes more intense in five minutes. Albumin, if present, should be separated before the application of this test. The test is very delicate and apparently reliable. 947. Diazo-reactian. — This reaction is one that is obtained in the urine of persons suffering from certain specific fevers, especially typho'd fever, mea- sles, septicaemia, and in some cases of phthisis. The test is made as follows : One grm. of sulphanilic acid is dissolved in a mixture of 350 c c. of water and 15 c.c. of hydrochloric acid. A second solution is made by dissolving .5 grm. of sodium nitrite in 100 c.c. of water. Five c.c. of urine are mixed with an equal volume of sulphanilic acid solution, and then with 3 or 4 drops of the sodium nitrite solution, and, finally, 10 drops of ammonia water. Normal iirine shows with this test a yellow or orange color with the precipitation of phosphates. In certain of the above-named diseases, especially in typhoid, the urine gradually assumes a carmine-red color. The froth produced on agita- tion is also distinctly red, and the prfecipitated phosphates show a green or violet color. Many phenol derivatives give a similar color reaction wiili the above test, and may lead to erroneous conclusions. According to Ehrlich, this reaction is characteristic of the urine in typhoid, measles, and acute tuber- culosis. Others deny the value of the test, the difference being possibly dqe to the interference of phenol derivatives. " 948. Ferments Found in the Urine. — Pepsin, trypsin, and a diastasic ferment have been found in the urine in addition to the organized ferments of lactic, butyric, and acetic acids, and urea. The pepsin ferment of the urine is said to be absent in the urine of typhoid fever, carcinoma of the stomach, and, according to some, in nephritis. Detection. — Pepsin is best detected by Sahli's method. A little pure fibrin is placed in the urine and set aside for several hours. It is then re- moved, placed in dilute HCl (.2 per cent.), and the mixture kept at a temper- ature of from 30° to 40° C. (86° to 104° F.). Any pepsin present in the urine is taken up by the fibrin, and the latter is slowly digested in the acid fluid.' The diastasic ferment is detected in the usual manner by its effect upon starch mucilage. The milk-curdling ferment has occasionally been found in the urine. See also Organized Ferments. 949. Ptomaines have been found in healthy urines as well as in mor- bid urines. In most fevers, especially in the specific and contagious fevers, the urine contains certain poisonous alkaloids. These cati be detected by first acidifying the urine and filtering from any mucus present, and then precipita- ting witli the doiible iodide of potassium and mercury. The precipitate, which contains the alkaloids, is distinguished from albumin or other substances by its solubility in alcohol at a gentle heat. The Diamins of the urine may be precipitated as benzoyl compounds by the action of benzoyl chloride and caustic potash. By this means cadaverin, putrescin, and other diamins have been detected in the urine of vesical ca- tarrh. Normal urine is said to be free from these bodies. URINARY DEPOSITS OR SEDIMENTS. 607 URINARY DEPOSITS OR SEDIMENTS. 950. Normal urine is clear, but on standing it will usually deposit more or less sediment. Urine that is turbid when passed will usually deposit a sediment which may contain mucus, pus, earthy phosphates, acid urate of sodium, or an abundance of epi- thelium from the kidney, ureters, or bladder. A turbidity which appears within a few hours after the urine is voided is most likely to be due to acid urates, the oxalate of lime, or the earthy phos- phates. When such a deposit is to be examined, a few ounces of the urine are set aside in a cylinder or tall vessel to allow the sediment to accumulate. The sediment may be removed from the solution by means of a pipette, or narrow glass tube, by holding the fingSr upon the upper end until it is depressed to the bottom of the glass, and then on removing the finger for an instant the sediment will be drawn up into the tube, when it may be removed for examination. To the crystalline deposits belong uric acid, urates, calcium oxalate, the phosphates or carbonates of mag- nesium and calcium, cystiii, hippuric acid, leucin, tyrosin, etc. Organized deposits may include mucus, blood, pus, casts, epi- thelium, fungi, and bacteria. The chemical examination of the deposits should be preceded by a microscopical examination. In fact, with a little experience, the microscopical examination will usually obviate the neces- sity of a chemical examination. Most of the unorganized and crystalline sediments may be easily recognized by microscopical as well as chemical means. 951. Crystalline Deposits. — Uric acid occurs in crystals deeply stained a brownish yellow to light leraon-yellow color, differing much in form and size. They are sometimes large, and when grouped together, as at (^), Fig. 65, are large enough to be seen with the naked eye. They dissolve when warmed with NaOH solution. The most characteristic are those -shown in Figs. 64 and 65. Acid Urates. — Amorphous urates consist principally of acid sodium urate. See Fig. 64. The deposit is amorphous unless a very high magnifying power is employed. Then it is seen to be rtiade up of minute globular panicles of a yellow, red, or brown color. This sediment separates only from acid urines. It dissolves to a clear solution on adding a solution of NaOH or KOH, or when heated. For the purpose of testing the solubility of the sediment under the micro- scope, it will be found convenient to place a drop or two of the solvent on the slide at one side of the cover glass, and put on the other side a piece of 6o8 MEDICAL CHEMISTRY. bibulous paper. In this way the fluid is drawn und'er the cover glass on the one side and removed at the other, the old liquid being replaced by the new. Fig. 64. .4 <£j ■ ' »4. ^. J-... i Deposit in "Acid Fermentation" of Ukine, (a) Fungus; (S) Amorphous Sodium Urate ; (c) Uric Acid ; (d) Calcium Oxalate. Fig. 65. Uric Acid, {a) Rhombic Tables (Whetstone Form) ; {i) Barrel Form; (c) Sheaves; {d) Rosettes of Whetstone Crystals. In this way the action of the reagent upon urinary sediments may be readily observed. URINARY DEPOSITS OR SEDIMENTS. 609 Acid sodium urate sometiraes crystallizes during the acid fer- mentation, in the form of larger spheres made up of elongated crystals. They appear under the microscope as yellowish or brown, frequently almost opaque spheres, with one or more spicules. When the urine becomes alkaline from fermentation, the amorphous urates are gradually converted into ammonium urate, which have the appearance seen in Fig. 66. Calcium oxalate occurs as a sedimeni in transparent, strongly refracting, regular octahedrons, .which are readily sol- uble in HCl, but insoluble in acetic acid. Tfiey frequently accompany uric acid crystals, and deposit during the acid fer- Deposit in Ahhoniacal Urine (Alkaline Fermentation). (a) Acid Ammonium Urate; (^) Ammonio-magnesium Phosphate; (<:) Bacterium Ure^e. mentation, as shown in Fig. 64. They are frequently called envelope-shaped crystals from the fancied resemblance to the reverse side of an envelope. They are usually of very small size, and occasionally appear in the form of dumb-bells. (Figs. 68 and 69.) A few isolated crystals of calcium oxalate have no clinical significance. They greatly increase after eating such vegetables as tomatoes, fresh beans, beet root, asparagus, etc. Oxaluria is a disease in which an unusually large proportion of oxalate of lime is found in the urine, together with certain well-marked nervous symptoms. It is usually here associated with an excessive amoupt of mucus and phosphates. 52 6io MEDICAL CHEMISTRY. Triple Phosphate. — Ammonium magnesium phos- phate occurs commonly in neutral or in alkaline urine. Oxalate of Lime, (a) Octa- HEURA; (3) Basal Plane of AN Octahedron forming a Rectangle ; (c) Compound Forms; (rf) Dumb-bells. Fig. 68. Perfect Dumb-bell Crystals of Oxalate OF Lime. The crystals are large, transparent, highly refracting prisms; usually in the form seen in Fig. 71. Occasionally it occurs in Fig. 69. A, Crystals of Cystin ; .5, Oxalate of Lime; (c) Hour-glass Forms ov B. the form of feathery crystals or star-shaped groups. They are never colored. They frequently attain a size sufficient URINARY DEPOSITS OR SEDIMENTS. 6ll to render them visible to the naked eye, especially in a strong light. Fig. 7D. a d Deposit from a Case of Inflamed Bladder (Ammoniacal Fermentation), (n) Detached Epithelium; (^) Pus Corpuscles; (f) Triple Phosphate; [d) Micro- organisms. Fig. 71. The Moke Usual Forms of Triple Phusphatb. X 300. Magnesium Phosphate is deposited occasionally in con- centrated urines of feebly alkaline reaction. 6l2 MEDICAL CHEMISTRY. Calpium Phosphate crystals appear as pointed, wedge- shaped prisms, either singly or in clusters. They are dissolved by acetic or hydrochloric acid. Calcium Sulphate is rarely present as a urinary sediment. It occurs in the form of long, colorless needles or prisms, or in elongated tables with abrupt extremities. Calcium Carbonate occasionally occurs in the urine as an amorphous deposit, but-on. higher magnification it is seen to be made up of minute spherical granules. (See Fig. 74.) Hippuric Acid occurs occasionally as a sediment in the Fig. 72. HlpPUKlC Aciu. urine in the form of four-sided prisms, either occurring separately or in groups. They are soluble in ammonia, insoluble in HCl. It occurs especially after the administration of benzoic acid, and the eating of certain fruits, as cranberries, bilberries, etc. Of no diagnostic importance. Cystin. — The crystals of this body appear as regular hexa- gonal plates, superimposed or contiguous to one another (see Fig. 69). They are insoluble in acetic acid, but soluble in am- monia. It is sometimes also found in solution in the urine. Leucin and Tyrosin always occur together. Tyrosin occurs URINARY DEPOSITS OR SEDIMENTS. 613 in, the sediment in the form of sheaves of very fine crystals.. Leucin, commonly associated with tyrosin, is more soluble, but occurs to some extent in the sediment in the form of small spheres, not unlike oil globules, which in a good light are seen to be marked with radiating striae. When quite pure, leucin crystallizes in delicate plates, but as it separates from the urine it usually forms little spheres (see Fig. 73). Tyrosin has been found in the urine, together with leucin, in phosphorous poison- FlG. 73. ^'mJ ■■■'-. '*^i I ■ I / ■-■■■ ^^w, -/ (fla)XEUCiN Balls: (^^) Tyrosin Sheaves; (c) Double Balls OF Ammonium Urate. ing, in acute yellow atrophy of the liver, leukjemia, and some ot the infectious diseases. Fat is deposited in the form of strongly refracting globules of varying size, and readily soluble in ether. It may be present in the urine in small quantities after fracture of bones, and in some chronic cases of Bright's disease attended with fatty degene- ration. In chyluria it occurs in greater abundance. Indigo occurs in the urine as concretions and amorphous fragments, and also in the form of blue crystals, and fine blue needles cohering together in clusters. The crystals of indigo are not rare in decomposing and fermenting urines. They occur 6i4 MEDICAL CHEMISTRY. more especially in the urine of hepatic abscess and cirrhosis of the liver. 952. Urinary Concretions of considerable size are occa- sionally to be seen in urine, with the naked eye. They consist, for the most part, of urates, or urates with uric acid. Their recogni- tion is important in the diagnosis of renal colic. Their color is usually red or brown when composed of uric acid or acid urates. Phosphatic concretions of larger size occur more rarely. They are light colored. Other concretions are occasionally met with. 953. Foreign Bodies occur in the urine from accidental causes, or from negligence in collecting the specimen. We may Fig. 74. (a) Spermatozoa ; {c) Amorphous Calcium Carbonate ; (^) Crystalline Magnesium Phosphate. mention fungi, yeast cells, microorganisms, fat globules, fibers of silk, linen, wool, feathers, wood, starch, etc. Bodies of this kind will be seen in almost every specimen examined. They will not cause any confusion after a little practice, as but one of the kind will usually be found, and they are so different from any of the sediments that mistakes will hardly be made. Fragments of tumors, as sarcoma, carcinoma, etc., may occasionally be found, and their import is self-evident. 954. Organized Deposits, — Mucous corpuscles are seen as round, finely granular cells, somewhat larger than blood URINARY DEPOSITS OR SEDIMENTS. 6iS corpuscles, and containing from 3 to 5 nuclei. They cannot be distinguished from the colorless blood corpuscles. (See Fig. 78.) Pus corpuscles resemble the mucous corpuscles in their ap- pearance. Water causes these corpuscles to swell, the nuclei becoming more distinct and the outline gradually disappearing. Acetic acid produces a similar change, but more rapidly. Solu- tions of KOH, NaOH, and NHjOH disintegrate these corpus- cles, destroying the cells and granules ; the nuclei are the last Fig. 75. (rt) Micrococci in Short Chains and Groups ; (d) SarciNjE : (c) Fungi from Acid Fermentation; {if) Yeast Cells from Diabetic Urine ; (e) Mycelium of a Fungus. to disappear. In alkaline urines, therefore, the mucous and pus corpuscles, if present, rapidly undergo disintegration. Epithelium cells of a variety of shapes are found in normal urine. Those from the convoluted portion of the tubules are poly- gonal in shape, but on remaining for some time in the urine, absorb water and become globular. They are a little larger than pus corpuscles, and may be distinguished from the latter by hav- ing one large, distinct nucleus. The epithelium cells of the loop of Henle and the larger collecting tubes are columnar in shape. 6i6 MEDICAL CHEMISTRY. Those from the ureter, pelvis, and urethra are elongated and conical, containing one nucleus near the centre. Large, flat epithelium cells are obtained from the bladder, vagina, and female urethra. (Fig. 76.) In chronic cystitis, after the large, flat, irregular cells have been shed off, we may have smaller, . rounded cells, having a large nucleus in comparison with the remainder of the cell. Old cells, slowly proliferated and des- quamated, have a smaller nucleus in comparison with the rest of Fig 76. 7 " e (rt) Epithelium from th^ Male Urethra ; fi) Vagina ; (t) Prostate ; (rf) Cowper's Glands ; {e) Littre's Glands ; (y) Female Urethra ; (^) Bladder. the cell. This is of importance in the diagnosis of new growths likely to be found in the bladder. Blood Corpuscles in the urine appear as small, round, disk-shaped corpuscles of a light straw or red color, and when seen on edge appear bi-concave. They are prone to changes in form and size on standing for some hours. They undergo decomposi- tion in alkaline urines, change their form, and finally become invisible. (Figs. 77 and 78.) 955. Casts. — Casts are fibrinous moulds of the uriniferous URINARY DEPOSITS OR SEDIMENTS. Fig. 77. 617 Ckenated Red Blood Corpuscles in the Urine. X 35°. Fig. 78. Colored and (a) Colorless Blood Corpuscles of Various Forms 6i8 MEDICAL CHEMISTRY. tubules and frequently contain blood or pus corpuscles, epithe- lium cells, crystals, or oil drops, imbedded in the substance of which they are composed, from which they are named epithelial casts, blood casts, granular casts, fatty casts, waxy casts, and hyaline casts. Hyaline Casts are perfectly clear, transparent cylinders with- out markings, having nearly the same refractive index as the urine, and consequently are not readily seen, especially in a strong light. (Fig. 79.) They are more readily seen with oblique illumination or by adding a drop of solution of eosin or fuchsin to the urine while the sediment is ^■°- 79- forming. They are characteristic of the very earliest and the recovering stage of nephritis, and are also found in con- FlG. 80. Hyaline Cast5. Blood Cast. gestion of the kidney, or in simple irritative catarrh of the tubules. Blood Casts contain blood corpuscles imbedded in them, and indicate an acute inflammation of the kidney and the escape of blood corpuscles from the circulation into the tubules. (See Fig. 80.) They are characteristic of the very acute stages of nephritis. Epithelial Casts are those in whose surfaces epithelium cells from the tubules are embedded. (See Fig. 81.) They indicate a shedding of the epithelium lining the tubules, and usually occur in the second stage of the inflammation, i. e., URINARY DEPOSITS OR SEDIMENTS. 619 when the inflammation has loosened the epithelium. They will usually be found only in acute nephritis. Granular Casts are those containing granules, either small or large. The granular matter may come from either the disin- tegration of the epithelium, blood cells, or from the material of the cast itself. They are frequently spoken of as finely granular, moderately granular, and coarsely granular ; the amount of gran- ular matter giving an idea of the amount of the destructive disintegration taking place in the kidney. The dense, coarsely granular varieties, as represented by Fig. 82, i5,.are more espe- cially found in the chronic cases. The finely granular cast seen Fig. 81. Granular Casts. Epithelial Casts. in Fig. 82, a, may be found in such cases, or in the subacute form of the disease. Fatty Casts, or Oil Casts, are such as reveal oil drops in the cast material. They occur in- chronic nephritis attended by fatty degeneration. It is sometimes difficult to determine whether the granular degeneration seen in these casts is due to the degeneration of the cast itself, after having been formed, or whether it is the result of the disintegration of blood or epithe- lium cells. These casts form in the tubules and often remain there for a considerable time — a sufficient time, perhaps, to un- dergo granular and even fatty degeneration. It is certain that 620 MEDICAL CHEMISTRY. the coarsely granular and fatty casts are never found in the first stages of the disease. Waxy Casts are a variety resembling hyaline casts in some instances, but are more dense and more distorted, and frequently are cracked or torn along the edges, or they have lost the regu- larity of their outline. They give a blue color with sulphuric acid and iodine. Mucous Casts are frequently spoken of. They are long, transparent, fibrillar bodies, twisted and branching, and lacking in the terminal, features of casts. They should not be regarded as casts, although we may meet with mucous plugs from the folli- cles in the prostatic urethra, which closely resemble casts. The character of the epithelium with which they are associated will usually serve to distinguish them. The absence of albumin will also assist. Casts can usually be readily distinguished from other bodies met with in the urine by the peculiarly rounded end, formed by the pushing of the cast material through the tubule by pressure from behind, while still in a plastic condition. This, rounded extremity is one of the most characteristic features in casts, and when in doubt as to the identity of an object this will often serve as a guide. Casts formed of urates will oc- casionally be met with and always resemble granular casts. (See Fig. 83.) Masses of micrococci closely resembling casts will also occasion- ally be seen, but these can usually be distinguished by their appear- ance or by their resistance to reagents, as caustic potash, nitric acid, • etc. Leucocyte Casts (Fig. 84) are met with in suppurating conditions of the tubules of the kidney. 956. Granular Detritus. — Under this name we will desig- nate the ill-defined granular or disintegrating masses of material frequently met with in cases of nephritis. These irregular or amorphous masses are probably due to partially disintegrated cells or masses of free granules of this origin. The amount of this material in any specimen of nephritic urine should be noted as an aid in arriving at a clear idea of the amount of destructive change going on in the kidney. This point is ari important one Fig. 83. URINARY DEPOSITS OR SEDIMENTS. 621 in prognosis, as by it we are able to determine that organic destruction of the kidney is rapidly progressing and the prog- nosis unfavorable; or, that there is little or no organic destruc- tion and the prognosis better. The following scheme for the chemical and microscopical ex- amination will be found useful as a guide to rapid work : — URINARY DEPOSITS. CHEMICAL EXAMINATION. White Deposit. Colored Deposit. (^ Insoluble on heating • 957. Draw off a portion of the sediment with a pipette or glass tube, ?nd transfer to a watch glass or small test-tube. ' Dissolves on heating urine, Ammonium ura/e. ( Sol. in NH4OH, Cj's/ine. f Soluble in acetic acid, jEartky Phosphates. Insol.inNHjOH, \' Insoluble in acetic acid. Calcium oxal- l_ ate or oxalurate. Gelatinizes in NH^OH, /"aj (see above). f Visibly crystalline (red), Uric aeid. I r Pale, easily soluble by heat, Urates. ^ Ainornho s J I^^^P <^ol°'^^d, slowly soluble by heat, ^^af ««'«!■« I 1 ivith uroerythriti. I Red, insoluble by heat, alkalies, or acids, . Blood. Deposit is Amorphous. MICROSCOPICAL EXAMINATION.- With a clean .pipette, draw off a small portion of the sediment, transfer to a clean glass slide, and examine with a ^ in. or ^ in. objective. A cover glass may be dispensed with. C Small granules with spicules on I larger granules, ( \\^\'L=Sodium urate. \ Vanishes on adding KOH or NaOH \ i&xV^Ammonium urate. I Permanent, " " " Calcium phosphate (rare). [ Globules, strongly refracting light, Fat. Reddish, cross or whetstone shape, or in group;;. Uric acid. Regular oclahedra, envelope-shaped, Calcium oxalate. Hexagonal plates, soluble in NH^OII (white) Cystin. Bundles of needles crossing each other, . . . Tyrosin. [ Large prisms, soluble in acetic acid (coffin-lid shaped), Amman, magnesium phosphate. I Brown, double spheres, spiculated. Urate of ammo- nium. ' I Club-shaped crystals, single or in groups. Calcium phosphate. Double spheres, radiated structure, soluble in acetic acid, with effervescence. Calcium carbonate (rare). Double spheres, insoluble in acetic acid. Calcium oxalurate (rare). Urine. Acid. Deposit is Crys- talline. Alkaline Urine. Cellular Elements. 622 MEDICAL CHEMISTRY. Double spheres, yellow, or red, radiated Uric acta. Red or yellow discs, biconcave; sometimes irregular in outline, Blood cells. Granulated corpuscles. Witli ") Albumen present Pus. dilute acetic acid show 3 >■ " absent, Mucus corpus- to 5 nuclei, J cles. Round, conical, or flat cells with one nucleus, Epitheliuhi from urinary tract. Tadpole-shape, with long tail, Spermatozoa. Cylinders, parallel margins, clear, granular, or containing epithe- lial cells as blood cells, .... Casts of iiriniferous tubules. Fungi, yeast, hairs, threads, etc., etc., . . Extraneous matters. URINARY CALCULI. 958. Urinary calculi, or concretions, are hard masses of urinary sediments formed in the kidney, ureters, bladder, or sinuses of the prostate gland. They are simple, or composed of one kind of material, or compound or mixed, composed of two or more kinds of material, deposited in concentric layers. In the examination of a calculus it should be sawed through so as to "expose these layers, and small portions of each layer exam- ined separately. An examination of a calculus is necessary to determine the condition which led to its formation, and to sug- gest proper treatmetit to prevent the formation of others. About 60 per cent, of all urinary calculi is composed of uric acid or acid urates. They are generally reddish and smooth, but some- times tuberculated. About 40 per cent, of the remainder of the stones is mixed uric acid and earthy phosphates, containing rather more of the latter ingredients. When the calculus starts as an uric acid concretion, and the urine changes from acid to alkaline, the phosphates are deposited. This is apt to occur sooner or later. The cross section of such a calculus shows very plainly the different layers. Calcium Oxalate, or mulberry, calculi comprise about three per cent, of all cases operated upon. They are gray or dark-brown, very hard, and generally tuberculated. When smooth are often called "hemp-seed calculi." The phosphatic calculi are rare, as are those composed of cal- cium carbonate, cystin, xanthin, fibrin, blood, indigo, and uro- stealite. These last are very rare, but have been met with. The following is a Scheme for the qualitative exam- ination of calculi : — URINARY CALCULI. 623 Heat a portion of the powdered stone on a platinum foil or charco'al with blowpipe. A. // chars and bums with a flame. Probably xanthin, cys- tin, urostealite, or fibrin. 1. The flame burns briefly, and the powder dissolves in am- monia, and on diluting deposits six-sided plates = Cystin. 2. It does not give the murexid test. The powder is soluble in HNO3 without effervescence, and ±he dried residue becomes orange with alkalies and red on warming = Xanthin. 3. The flame is yellow, prolonged, and gives the odor of burning shellac. The powder is soluble in alcohol ^ Uro- stealite. 4. The flame is yellow, prolonged, and gives the odor of burning feathers. Soluble in hot KOH solution, and is precip- itated again by acetic acid = Fibrin. B. It chars, but does not bum with flame. I. The powder gives the murexid test. a. It gives off' NH, when warmed with KOH solution = Urate of Ammonium. b. It gives no NH3 with KOH = Uric Acid. C. The powder does not strongly char or burn. Treated with dilute HCl. 1. It dissolves with effervescence = Calcium Carbonate. 2. It dissolves without effervescence, and the solution gives a white precipitate with NH^OH = Phosphates or Calcium Oxalate. Treat the powder with acetic acid. Phosphates dissolve without effervescence. Mixed phosphates fuse in heating on foil. Calcium phosphate does not fuse. Triple phosphate gives off NH3 when warmed with a little KOH solution. Calcium oxalate is insoluble in acetic acid. After ignition it gives alkaline powder, which effervesces with acetic or dilute HCl. 624 MEDICAL CHEMISTRY. THE URINE OF THE TWENTY-FOUR HOURS— NORMAL AND PATHOLOGICAL. 959. The subjoined table gives the most prominent variations in physical and chemical characters, with brief notes of their significance. As there are numerous handbooks upon this sub- ject, the student is referred to them for details : — Physical Charactbk. Normal. Alterations in Abnormal Conditions. Colo Transparency. Consistence. Odor. Reaction. Pale straw to reddish-yel- low. The average col- or is Amber. Clear, with only a slight flocculent cloudofmu cus. When normal, urine is mo bile, like water. Peculiar to it- self. Slightly acid; becomes moreacidon standing, then b e- comes alka- line. Colorless: neuroses, chronic nephritis, diabetes. High colored: acute fevers. Blood red : blood 01' foreign color. Dark brown : hcematuria, poisoning by carbolic acid, potass, chlorate, or iodoform. Smoky brown : presence of decomposed blood in acute nephritis. Yellow or green : presence of bile. White : chyle or pus. Urine turbid when passed, is abnormal. Whitish sediment may be pus, phosphates, or ammo- nium urate. When viscid, it indicates albumin, bile, or pus. Urintf putrid when passed, indicates cystitis. Urine strongly acid in fevers and inflammations of liver, heart, and lungs; in acid dyspepsia. Urine is alkaline in cystitis, and occasionally in debility, chlorosis, certain organic nervous diseases, typhus, etc. Constituents. Amount in Grains. Alterations in Pathological Conditions. Sulphuric acid. Phosphoric acid. 23 to 38 46 to 54 Having more or less the same source as urea it will increase or diminish therewith. Occurs as sulphuric ethers. Increased in fevers, in nerve exhaustion dis- ease of spinal cord, and in tubercle of the lung. In phosphatic diabetes the alkaline phosphates are greatly increased. URINARY CALCULI. 625 THE URINE OF THE TWENTY-FOUR HOURS— NORMAL AND PATHOLOGICAL.— Con/?"«a035 1-5552 APOTHECARIES' WEIGHT, lb S S 9 gr.. - Pound. Ounces. Drachms. Scruples. Grains. I 12 . . . .96 288 5760 I . . . . 8 24 480 I. ... 3 60 Graintnes, 373-2419 3' -1035 38879 1.2959 .C648 AVOIRDUPOIS WEIGHT. Found. Ounces. Drachvis. Grains. Grammes. I 16 ... . . . 256 7CXJ0 = 453-5926 I 16 437-5 = 28.349s I 27-343 = 1-7718 METRIC MEASURES. MEASURES OF LENGTH. Millimeter = o.ooi of a meter. Centimeter = o.oio of a meter. Decimeter = o.ioo of a meter = about 4 inches. Meter = i.ocx} Meter = 39.37 inches. Decameter == 10.000 meters. Hectometer = 100.000 meters. Kilometer = 1 000 000 meters — about ^ of a mile. Myriameter = io,coo.ooo meters ^= about 6>^ miles. MEASURES OF SURFACE. I Centiare = I Square meter = about 1^ square yards. X Are = 100 Square meters. I Hectare = 10,000 Square meters == about -2.% acres. MEASURES OF VOLUME. Cubic centimeter = o.ooi of a liter. Litre (cubic decimeter) = icoo. cubic centimeters. Cubic meter = 1000 cubic decimeters. Cubic meter = 1000. liters, or 1 kiloliter. Cubic meter = i stere. I Milligramme = I Centigramme = I Decigramme = I Gramme* = r Decagramme == I Hectogramme = 1 Kilo(gramnie) = I Tonneau = MEASURES OF WEIGHT. O.OOI of a gramme o 010 of a gramme. 0.100 of a gramme. 1.000 Gramme 10.000 grammes. 100.000 grammes. 1000.000 grammes 1000. Kilos about g"]- of a grain. about \^% grains. about 2^ fl>s. about I ton. * Sometimes spelled gram in English and American books. APPENDIX. 633 TABLES FOR THE CONVERSION OF WEIGHTS AND MEASURES. Based upon the value 39.37 in. for the meter and 15432.2 grains for the kilogramme. ■ The following tables embrace the chief measures of length, weight, and capacity, giving the required equivalents of the nine units. Higher numbers are found by moving the decimal point to the right, and fractions by moving it to the left. Thus, if it be desired to find the equivalent of 125 grains in milli- grammes, we proceed as follows : By the table 1 gr. :=: 64 80 mgrms., and 100 grs. thea = 6480. mgnns. 2 grs. = 129.6 " " 20 " " = 1296. " S gfs. = 324- " " S " " = 3^4- " 125 grs. 8100. milligrammes. As 1000 mgrms. = 1 grm., the above would be 8.100 grms. If it be desired to find the value of 1.45 grms. in grains we proceed as follows: — I grm. = = 15.43 grains. 4 grms. = 61.72 grains .4 gms. = 6.172 " 5 grms. = 77.15 " .05 " = .7715 " 22-3735 grains. Milli- Grains. Mgrms. Inches. meters. Fl. Oz. c.c. Minims. I = 64.8 I = 25.4 I = 29.7 I = 16.2 2 = 129.6 2 == 508 2 = 600 2 = 32.4 3 = '94-4 3 = 76.2 3 = 90. 3 = 486 4 = 2592 4 = IOI.6 4 = 120. 4 = 64.8 5 = 324.0 5 = 127.0 5 = 150. 5 = 81.0 6 = 388.8 6 = 152.4 6 = 180. 6 = 97-2 7 = 453-6 7 = 177-8 7 = 2ZO. 7 = "3-4 8 = 518.4 8 = 193-2 8 = 240. 8 = 129.6 9 = 583-2 9 = 228.6 9 = 270. 9 = 145-8 Troy. Oz. Grms. Feet. Meters. Pints. Liters. c.c. Fl. Drachms. I = 31. 1 I = 0.3048 I = 0-473 I = 0.27 2 = 62.2 2 =: 0.6096 2 = 0.946 2 = 0.54 3 = 93-3 3 = 0.9144 3 = 1.419 3 = 0.81 4 = 124.4 4 = I. 2192 4 = 1.892 4 = 108 5 = iSS-S 5 = 1.5240 5 = 2-365 5 = '•35 6 = 186.6 6 = 1.8288 6 = 2.838 6 = 1.62 7 = 217.7 7 = 2.1336 7 = 2.311 7 = 1.89 8 = 248.8 8 = 2.4384 8 = 3-784 8 = 2.16 9 = 279-9 9 = 2.7432 9 = 4-257 9 = 2.43 54 634 MEDICAL CHEMISTRY. Av. Oz. Minims. c.c. Grms. Grains. Liters. Fl. Oz. I = 28-35 I =; .0616 I ::= 15-43 I = 33-8 2 = 56.70 2 = .1232 2 = 30.86 2= 67.6 3 = 85.05 3 = .1848 3 = 46.29 3 = 101-4 4 = 113.40 4 = .2464 • 4 = 61.72 4=135-2 5 = 141.7s 5 = .3080 5 = 77-15 5 = 169.0 ■ 6 = 170.10 6 = .3696 6 = 92.58 6 = 202.8 7 = 19845 7 = -4312 7 = 108.01 7 = 236.6 8 = 226,80 8 = .4928 8 = 123-44 8 = 270.4 9 = 25515 9 = -5544 9 = 138-87 9 = 304.2 Av. KlLO- Fl. Cu. Pounds. Grhs. Drachms. c.c. Kilos. Av.Oz. Liters. Inches. I = 0-4536 I = 3-7 I = 2.2 1= 61. 2 = 0.9072 2 = 7-4 2 ^ 44 2 = 122. 3 = 1.3608 3 = II. I 3 = 6.6 3 = 183. 4 = I.8I44 4 = 14.8 4 = 8.8 4 = 244. 5 = 2.2680 5 = 18.S 5 = II.O 5 = 305- 6 = 2.7216 6 = 22.2 6 = 13-2 6 = 366. 7 = 3-1752 7 = 259 7 = 15.4 7 = 427- 8 = 3.6228 8 = Z9.6 8=^ 17.6 8 = 488. 9 = 4.0824 9 = 33-3 9 = 19.8 9 = 549- APPENDIX. 635 AEPHABETICAL TABLE OF EQUIVALENT MEASURES. I Are .= 100 sq. meters = 1 19.6 sq. yards. 1 Barrel (wine) . - . = 1.192 hectoliters. I Barrel (imperial) ". =1.635 hectoliters. I Bushel (dry) ^35.243 liters. I Centimeter = ^^^ mer = .3937 inch. I Cubic centimeter = 1 6.2 minims = .06102 cu. in. I Cubic centimeter of dist. water at 4° C weighs i gram. I Cubic decimeter (I liter) (1000 c.c.) of dist. water . . weighs I kilogram. 1 Cubic decimeter (imperial measure) ....== 61.03 <^"- 'd. = 0.8804 qt. I Cubic decimeter (American wine measure) = 33.8 fluid ounces or 1.056 qts. I Cubic foot = 1628 cu. in. ^= 28,315.31 c.c. I Cubic foot of water at 62° F. (16.6° C.) weighs 62.32 lbs. av. I Cubic inch . *. = 266 minims = 16.386 c.c. I Cubic inch of water at 62° F. (16.6° C.) weighs 252.46 grs. = 16.372 grams. I Cubic meter ( I stere) = 1000 liters ^ 35.30 cu. ft. I Drachm (Troy) = 3.888 grams = 60 grains. 1 Fluid drachm =60 minims = 3.697 c.c. I Fluid ounce (imperial) = 28.4 c.c. = 1.7329 cu. in. I Fluid ounce (wine measure) = 29.57 c.c. = 1.8047 cu. in. I Fluid ounce of water (wine measure") at 62° F weighs 456 grains. " Fluid ounce of water (wine measure) at 60° F. ... weighs 29.57 grams. I Fluid ounce of water (imperial) at 62° F weighs 437.5 grains. I Foot (12 inches) =: 34.48 centimeters. I Gallon (imperial) = 277.27 cu. in. = 4 543 liters. I Gallon (wine) = 231 cu. in. = 3.785 liters. I Gallon of water (imperial) . . . . weighs 10 lbs. Wine gallon, 8.34 lbs. I Grain Troy -. = 0.0648 gram. I Gram (weight of I c.c. of water at 4° C. (39.2° F.) . . = 15.4233 grains. I Inch = 2.54 centimeters. I Kilogram ^= 1000 grams = 2.7 lbs. Troy = 2.2046 lbs. av. I Liter (see cubic decimeter) 61.027 cu. in I Meter (one forty-millionth of earth's meridian) =39.3708 in. I Minim = 0.0616 c.c. i minim of water weighs 0.95 grain. I Ounce (Troy) = 480 grains = 31.1 grams. I Ounce (avoirdupois) = 437.5 grains = 28.35 grams. I Pint (imperial) =20 fluid ounces = 567.93 c.c. 1 Pint (wine measure) =16 fluid ounces := 473-15 c.c. I Pound (Troy) = 5760 grains =373.24 grams. I Pound (avoirdupois) ' 7000 grains = 453.59 grams. 1 Quart (imperial), 40 fluid ozs = 69.97 cu. in. = 1.1358 liters. I Quart (wine measure), 32 fluid ozs = 58.30 cu. in. = 0.9463 liter. I Ton (avoirdupois) . . = 2000 lbs. = 29,167 ozs. Troy=907.20 kilograms. I Tonneau = 1,000,000 grams ^ 1000 kilos ^ 2204.6 lbs. av. 636 MEDICAL CHEMISTRY. TABLE OF SPECIFIC GRAVITIES NAMED IN THE U. S. PHARMACOPCEIA, 1890. Compiled by Dr. J. F. Golding. AT 15° C- Acidum aceticum, about 1.048 '* " dilutuni, . . .about 1.008 " '* glaciale, not higber than 1.058 ** hydrobromicum dilutum, about 1.077 '• hydrochloricum, . . . about 1.163 •* " dilutum, about 1.050 " hypophosphorosum dilutum; about 1.046 " lacticum, about 1.213 *' nitricum, about 1.414 " ** dilutum, . . about 1.057 " oletcu'm, about o goo " phosphoricum, . . not below 1.710 ** ** dilutum, about 1.057 ". sulphuricum, . . . not below 1.835 ** " aromaticum, about 0.939 " " dilutum, . about 1.070 ** sulphurosum, . not less than 1.035 Adeps, about 0.932 Ether,* o 725 to 0.728 " aceticus, 0.893 t0'o.8g5 Alcoholjf about 0.820 " absolutum,J . not higher than 0.797 " deodoratum,g . '. abouto8i6 ** dilutum, II about o 937 AmylNitris, 0,870 lOi).88o Aqua ammbniEe, ... 0.960 " -" fortior, 0.901 " hydrogeniidioxidi, about i.od6 to 1.012 Balsamum peruvianum, , . , 1.135 to 1.150 Benzinum, o 670 to o 675 Bromum, 2.990 Camphora, ; 0-995 Carbonei disulphidum, .... 1.268 to 1.269 Cera alba, 0.965 to 0.975 '* flava, 0.955100.967 Cetaceum, about 0.945 C'hloroformum,lf . . . . not below 1.490 Copaiba, 0.940100.990 Creasotum, not below i 070 Eucalyptol, 0.930 Fel bovis, 1.018 to 1.028 Glycerinum, not less than 1.250 Hydrargyrum, 13-5584 lodoformum, 2 000 lodum, **: Limonis succus, . . not less than 1.030 Liquor ferri acetatis, . . . about 1. 160 " " chloridi, abouti.387 " *' citratis, .... about 1.250 " " nitratis, .... about 1.050 AT 15° C. Liquor ferri subsulphatis, . . . about 1.550 " *' tersulphatis, . . about 1.320 " hydrargyri nitratis, . , about 2.100. " plumbi subacetatis, . . about 1. 195 " potassse, about 1.036 " sodae, about 1.059 ** " chloratae, .... about 1.052 *' sodii silicatis, . . . 1.300 to 1.400 " zinci chloridi, about 1.535 Mel, I-37S Methyl salicy las, 1.183101.185 Oleum adipis, 0.910 to 0.920 " iEthereum, 0.910 " amygdalae amarse, . . 1.060 to j.070 *' " expresgum, 0.915100.920 " anisi, ft " aurantii corticis, .... about 0.850 " " florum, , . . 0.875 to o 890 ** bergamottae, . . . . 0.880100.885 " cadinum, ...... .about 0.990 *' cajuputi, 0.922100.929 *' cari, ; . . . 0.910 to 0,920 " caryophylli, 1.060101.067 " . chenopodii, about 0.970 " cinnamomi, 1.055 to 1.065 " copaibae, 0.890 to 0.910 " coriandri, 0.870 to 0.885 " cubebse, aoout 0.920 " erigerontis, about 0.850 " eucalypti, 0.915100.925 " foeniculi, . . . . not less than 0.960 " gaultherise, 1.175101.185 '* gossypii seminis, . . . 0.920 to 0.930 " nedeomas, 0,930100.940 " juniperi, 0.850 to 0.890 " lavandulas florum, , 0.885 to 0.897 '* limonis, 0.858 to 0.859 " lini, 0.930 to 0.940 " menthae piperilae, , . 0.900 to 0.920 ** •' viridis, . , .0.930100.940 ** morrhuae, 0.920 to 0.925 ** myrciae, 0.975 to 0.990 " myristicse, 0.870100.900 " olivse, 0*915 to o.gi8 " picis liquidae, about 0.970 " pimentse, 1.045 to 1.055 " ricini, 0.950 to o.g70 ". rosae, JJ ** rosmarini, . . . . 0.895 to o.gis " sabinae, o.gio to 0.940 "■ santali, ....... o.g7o to 0.978 " sassafras, 1.070 to i ogo *' sesami, . . . o.gig to 0.923 * 0.714 to 0.717 at 25° C. t 0.812 at 25° C. X 0.789 at 25O C. g 0.808 at 25° C. I About 0.937 at 15° C; about 0.936 at 15.6° C., and about 0.93a at 25° C. 1[i.i73at250C. ""■'= 4.948 at 17° C. ■f-f About 0.980 to 0.990 at 17O C. Jt 0.865 to 0.880 at 20° C. APPENDIX. 637 TABLE OF SPECIFIC At 15° c. Oleum sinapis volatile, . . . 1.018 to 1.029 " terebinthinae, .... 0.655 to 0.870 *' " rectlficatuin, 0.855 to 0.865 " theobromatis, . . . . o 970 to 0.980 ** thymi, 0.900 to 0.930 " tiglii, 0,940 to 0.960 Petrolatum Hquidum, . about 0.875 to 0.945 " molle, * *' spissum, f Phosphorus, % Resina, 1.070 to 1.080 Spiritus aetheris nitrosi,, ahout 0.836 to 0.842 " ammoniae, about 0.810 " '* aromaticus, . about 0.905 GRAVITIES. (Canttnued.) At 15O c. Spiritus frumenti, . not more than o 930 nor less than 0.917 ** glonoini, 0.826 to 0.832 " vini gallici, . . not more than 0.94Z nor less than 0.925 Syrupus, . about i. 317 ** acidi hydriodici, . . . about 1.313 ** ferri iodidi, . . . . about 1.353 Terebenum, about 0.862 " ' ' * 1 liquefied — lighter than water Tinctura ferri chloridi, . . . ■. about 0.960 Vinum album 3 " rubrum, | Zincum, 6.9 (cast) to 7.2 (rolled) Table showing the Solubility of some Chemicals in Glycerin. One Hundred Parts of Glycerin Dissolve the Annexed Quantities of the Salts. — (Klever.) Parts. Arsenious Oxide, 20.00 Arsenic Oxide, 20.00 Acid, Benzoic 10.00 " Oxalic 15.00 " Tannic, 50.00 Alum, 40.00 Ammonium Carbonate, . . . 20.00 " Chloride, . . . 20.00 Antimony and Potassium Tar- trate, 5.50 Atropine, 3.00 " Sulphate 33.00 Barium Chloride, 10.00 Brucine 2.25 Cinchonine, 0.50 " Sulphate, . . . 6.70 Copper Acetate, 10 00 " Sulphate 30.00 Iron and Potassium Tartrate, 8.00 " Lactate, 16.00 " Sulphate, 25.00 Mecuric Chloride, 7.50 Mercurous Chloride, .... 27.00 Iodine, 1.90 Morphine, 0.45 Morphine Acetate, . . . " Hydrochlorate, Phosphorus, . . Plumbic Acetate, . Potassium Arsenate, " Chlorate, " Bromide, " Cyanide, " Iodide, . Quinine " Tannate, . Sodium Arsenate, . " Bicarbonate, " Borate, . . " Carbonate, " Chlorate, . Sulphur, . ... Strychnine, .... " Nitrate, " Sulphate, Urea, Veratrine, .... Zinc Chloride, . . ■' Iodide, . . . " Sulphate, . . Parts. 20.00 20.00 0.20 20.00 50.00 3-50 25.00 32.00 40.00 0.50 0.25 50.00 8.00 60.00 98.00 20.00 o.io 0.25 4.00 22.50 50.00 1. 00 50.00 40.00 35.00 * About 0.820 to 0.840 at 60° C. t About 0.840 to 0.850 at 60° C. t 1.830 at 10° C. } Not less than 0.990, nor more than i.oio at 15.6° C. II Not less than 0,989, nor more than i.oio at 15.6° C. 638 MEDICAL CHEMISTRY. SOLUBILITY OF THE MOST IMPORTANT CHEMICALS USED IN MEDICINE, IN WATER AND ALCOHOL. Explanation of Signs. J. = soluble; «»j. = insoluble ; j/. = sparingly insoluble; v. soluble ; aim. = almost ; dec. = decomposed. very Name of Chemical. Water. At 59° F. or 15° C. At 59° F., or 15O C. grs.pr.fSj, Alcohol. At 59° F., or 15O C. AtS9°F., or 15O C. grs.pr.fSj. One part is soluble in :— Acetanilid, Acid Arsenious, " Benzoic, " Boracic, " Carbolic " Chromic, " Citric, " Gallic, " Salicylic, " Tannic " Tartaric Alum, " Dry (Exsiccatum), . . . Aluminium Hydroxide, . . . . " Sulphate, Ammonium Benzoate " Bromide " Carbonate, . . . . " Chloride, . . . . " Iodide " Nitrate " Phosphate, . . . . " Sulphate, . . " Valerianate, . . . Amylene Hydrate, Antimony and Potass. Tartrate, " Oxide " Sulphide, Antipyrin, " Benzoate Apomorphine Hydrochlorate, . Apyonin, Anthrarobin Silver Cyanide ;' Iodide Parts. 200 30-80 500 25 20 2.28 IS-2-S 7 0.9 18.2 22.8 0-7S 100 45° 6 0.7 lo.s 20 ins. 1.2 S i-S 4 3 I o-S 4 1-3 V. s. 608 45 1. 01 76 651 43-4 22.8 "380' 91:1 300.4 U4 152 456 910 114 350-7 Parts. 10 sp. 3 IS V. s. dec. I 4-S- 2.S 0.6 2.5 ins. ins. ins. aim. ins 28 150 dec. 1-37 9 20 o.s sp. ms. "7 aim. ins. ins. I s. s. 6.8 26.8 456 '67' ms. ins. ins. 5 ins. ins. ins. I sol. 50 sol. s ins. ins. 37-4 124.6 24.9 374 83.1 149.6 623 149.6 13-3 2.4 273 41-5 18.7 748 75 374 7-4 75 APPENDIX. 639 SOLUBILITY OF THE MOST IMPORTANT CHEMICALS USED IN MEDICINE, IN WATER AND ALCOHOL. {Continued.) Name op Chemical. Water. At 59° F., orisOC; At59°F., or 15° C. grs.pr.fSj. Alcohol. At 59° F., or i5°C, At 59° F., or 15OC. grs. pr.fSj. Silver Nitrate " Nitrate (fused), . . . " Oxide, Arsenic Iodide Atropine, " Sulphate, .... Benzanilid Senzonaphthol Benzophenoneid, Benzosol, Belol, Bismuth Citrate " and Ammon. Citrate, " Subcarbonate, . , . " Subnitrate, .... Bromacetanilid Bromine Bromoform Bromol, Caffeine, Calcium Bromide " Carbonate " Chloride, " Hypophosphite, . . . . " Phosphate (precipitated), Lime (Calx), Camphor, Monobromated, . . . . Cerium Oxalate,* Chinolin, " Salicylate, " Tartrate, Chloral, Chloralamid, Cbloralammonium, Chloral urethan, Cinchonidine Sulphate, Cinchonine, " Sulphate Codeine 0.8 0.6 V. Sp. 3S 600 0.4 ins. ins. 100 ins. ins. ins. V. 3. ins. ins. ins. 33 300 prac. ins 75 0.7 ins. 1-5 6.8 ins. 7S0 aim. ins. ins. ins. 80 80 570 760 10 ins. 160 aim. ins. 70 80 130.2 0.7 1152 4.6 13-8 1.6 6.08 65. 300.4 67 0.6 5-7 5-7 4S.6 4-5 6.5 5-7 25 25 ins. 10' V. s. 6.5 60 sol. sol. diffic.sol ins. sp. ins. ins. diffic.sol. dec. freely sol. freely sol. 35 .1 ins. 8 ins. ins. ins. V. ». ins. 5 sol. 150 V. a. ^-3 71 no 6 V. s. 14-3 14.9 37-4 57-5 6.2 10.6 374 46.7 74.8 ' 3-8 i87 ■ (124.6) 5-2 3-4 62.3 640 MEDICAL CHEMISTRY. SOLUBILITY OF THE MOST IMPORTANT CHEMICALS USED IN MEDICINE, IN WATER AND ALCOHOL. {Continued.) Name of Chemical. Chalk (Creta), Copper Acetate " Sulphate, Creolin, . . Creasote, . . Cresalols, . . Cresol Iodide, Cresotic Acid, Dermatol, . Di-iodo p Naphthol Ditbiosalicylic Acid I, " " If, Diuretin, .... Elaterium, . Ethyl Bromide, . Ethylene Bromide Euphorin, . . . Europhen, . . . Exalgin, .... Ferric Chloride, . " Citrate, . . " and Ammon. Citrate, . " " " Sulphate, " " " Tartrate, " " Potass. Tartrate, . " " Quinine Citrate, . " " Strychnine Citrate, " Hypophosphite, *' Lactate, . . " Oxalate, . . " Hydrate, . . " Phosphate, . " Pyrophosphate; " Sulphate, . . " Valerianate, . Fluorescein, . . . Gallacetophenone, . Guaiacol, Hydracetin, .... Hydronaphthol, . . Hydroquinone, . . Water, At 59° F-. ori5°C. ins. IS 2.6 ins. ins. ins. s. s. ins. ins. ins. ins. V. s. ins. ins. ins. ins. ins. s. s. V. s. s. V. s. 3 V. s. >r. s. s V. s. sp. 40 sp- ins. V. s. V. s. 1.8 ins. s. 500 85 50 s. s. At E9° F., or i5°C. grs.pr.f5j. At59°F., orisOC. 30.2 I73-I 152 114 2S3-3 0.9 5-3 91 Alcohol. At 59° F., or 15O C. grs.pr.fSj. ins. 13s ins. s. V. a. S. ins. s. s. irs. V. s. 125 s. V. s. ins. ins. ins. ins. ins. ins. ins. ins. aim. ins. ins. ins. ins. ins. ins. V. s. 2.7 2.9 APPENDIX. 641 SOLUBILITY OF THE MOST IMPORTANT CHEMICALS USED IN MEDICINE, IN WATER AND ALCOHOL. {Continued.) Name of Chemical. Waxes. At59°F., or 15° C. At 59°F., ori5°C. grs.pr.fSj. Alcohol. At59°F., or 15° C. At59°F., orisOC. grs.pr.fSj. Hydroxykmine Hydrochlorate, Hyoscyamine Sulphate, . . . . Hypnal Hypnone . . . Ichthyol lodantipyrin, Iodine, Iodoform, lodol lodophenin, Kairia, Lanolin .456 IS 5-6 ins. 91.2 (76) Lithium Benzoate, " Bromide " Carbonate, " Citrate, " Salicylate Lysol, Magnesium Oxide, " Carbonate, " Sulphate, " Sulphite, Manganesium Dioxide (Black Oxide), , " Sulphate, , Mercuric Chloride, Mercurous Chloride, Mercuric Cyanide, " Iodide (Red), Mercurous Iodide (Green), . . Mercuric Oxide, " Subsulphate " Sulphide (Red) Mercury Sozoiodol, Metaldehyde, Methacetin, Methylal, Methyl Chloride, Methylene (Blue), " Chloride, Microcidin s. s. sp. ins. ins. 4 V. s. 130 5-5 1. s. V. s. aim. ins. aim. ins. 0.8 20 ins. 0.7 16 ins. 12.8 aim. ins. aim. ins. ins. ins. ins. 500 ins. 53° 3 4 vol. s. s. s. s. 3 76 114 3-5 837 570 22.8 es'i ' 28s 3-S 0.9 0.8 152 152 II 80 3 s. 20 80 (78° C.) 12 V. s. ins. sp. V. s. V. s. ins. ins. ins. ins. ins, ins. . 3 ins. 15 130 . ins. ins. ins. ins. s. s. S. 35 vol. s. 23.6 34 4.65 137 4-7 3I-I 124 24.9 2.8 642 MEDICAL CHEMISTRY. SOLUBILITY OF THE MOST IMPORTANT CHEMICALS USED IN MEDICINE, IN WATER AND ALCOHOL. {Continued.) Name of Chemical. At 59° F., orisOC. At59°F, ori5°C. gre.pr.fSj Alcohol. At59°F., or I5°C, At 59° F., ori5°C. grS.pr.fSj. Morphine, " Acetate " Hydrochlorate, . . " Sulphate, Naphthalene, Orexin Hydrochlorate, . . . a-Oxynaphtoic Acid Paraldehyde, Pental, Fhenacetin, Phenocoll Acetate, " Carbonate " . Hydrochlorate, . . . " Salicylate, Phosphorus Physostigmine Salicylate, . . . Picrotoxine, Pilocarpine Hydrochlorate, . . Piperazine, , . . Piperine,' • . Plumbic Acetate, " Carbonate " Iodide, " Nitrate " Oxide Potassium Hydrate, " Acetate " Bicarbonate " Bichromate, ..... " Bitartrate, " Bromide " Carbonate, .... ',' Chlorate, " Citrate " Cyanide " and Sodium Tartrate, " Ferrocyanide, . . . " Hypophosphite, . . " Iodide, " Nitrate, " Permanganate, . . . V. p. 12 24 24 1000 V. s. 38 19 0.4 63 702 s. V. s. ins. 10 ins. ins. 35 ins. 16 s. ins. 1.30 150 V. s. V. S. 45.6 130.2 10 s. V. s. s. s. 28.S 3-S 3-4 V. sp. 12 10 V. S. aim. ins. 1.8 ins. 2000 2 ins. O-S 0.4 32 10 210 1.6 I 16.S 0.6 2 2.5 4 0.6 0.8 4 20 253-3 0.2 228 910 112.S 142.5 45-6 2.1 285 456 27.6 760 228 182.4 114 760 570 114 22.8 30 8 ins. V. sp. aim. ins. ins. 2 2-S aim. ins. ins. V. sp. 200 ins. V. sp. V. sp. sp. aim. ins. ins. 7-3 18 aim. ins. dec. 3-7 S-S 5-9 o.s 37-4 3I-' 37-4 IZ.4 46.7 187 149.6 1.8 51 20.7 APPENDIX. 643 SOLUBILITY OF THE MOST IMPORTANT CHEMICALS USED IN MEDICINE, IN WATER AND ALCOHOL. {^Continued.) Name of Chemical. At 59° F., orisOC. At59°F., ori5°C. gre.pr.fSj. At59°F. orii°C. At 59° F., or i5°C. grs.pr.fSj. Potassium Sozoidol, " Sulphate, " Sulphite, " Tartrate, Pyoctanin Blue (Methyl-violet), Pyridin Pyrocatechin, Qainidine Sulphate, Quinine, " Bisulphate " Hydrobromate, . . . " Hydrochlorate, . . . " Sulphate, " Valerianate Resopyrin, Resorcin, Sugar, Cane, " Milk, Saccharin, Salicylamid, Salipyrin, Salol Solophen, Salicin, Santonin Sodium Hydroxide, " Acetate " Arseniate, " Benzoate " Bicarbonate, " Bisulphite " Borate (Borax), . . . " Bromide, " Carbonate, " Chlorate, " Chloride, " Hypophosphite, . . . Hyposulphite " Iodide " Nitrate " PaJ-acresotate SO 9 4 0.7 So(?l s. 100 1600 10 16 34 740 100 ins. 2 O-S 7 400 250 s. s. ins. ins. 28 aim. ins. 1-7 3 4 1.8 12 4 16 1.2 1.6 i.t 2.8 I i-S 0.6 1-3 9.12 50.6 114 651 sp. aim. ins. 4.5 0.2 45. 6 28.5 13-4 0.6 4-5 228 ' 910 65.1 1. 14 1.82 16.2 268.2 152 114 253-3 38 114 28.5 380 285 44-S 162.8 456 300.4 .76 350-7 6 32 3 3 65 S S s. 1.75 ins. 30 s. s, 10 V. s. 30 40 V. s. 30 V. sp. 45 ins. 72 ins. 13 ins. 40 aim. ins. 30 ins. 1.8 sp. 374 "46.7 62.3 11.6 124.6 124.6 5-7 74.8 75 124.6 37-4 12.4 9-3 12.4 ■ 8.i 5-2 '28.7 9-3 12.4 207 644 MEDICAL CHEMISTRY. SOLUBILITY OF THE MOST IMPORTANT CHEMICALS USED IN MEDICINE, IN WATER AND ALCOHOL. {Continued.) Name op Chemical. Water. At59°F., ori5°C. AtS9°F., or i5°C. grs.pr.fSj. Alcohol, At =9° F., or 15° C. At59°F., erisOC. grs.pr.fSj. Sodium Phosphate, . . " Pyrophosphate, . " Salicylate, . . . . " Santoninate, . . " Sozoidol, . . . " Sulphate " Sulphite, . . . " Sulphocarbolate, Sozoiodol, Strychnine, " Sulphate, . . Sulphaminol, Sulphonal, Sulphosalicylic Acid, . . Sulphur, Tetronal, Thallin Sulphate, . . . " Tartrate, . . . Thiol Thiophen, Thioresorcin, Thymacetin Thymol Trional Urethane, Veratrine Zinc Acetate, " Bromide " Carbonate, .... " Chloride " Iodide, " Oxide, " Phosphide " Sozoiodol " Sulphate " Valerianate, . . . 6 12 i-S 3 14 2.8 4 5 s. 6700 10 ins. 450 s. ins. 4SO 7 10 s. . ins. 76, 38 300.4 152 32-4 162.8 114 91.2 0.06 45.6 I 6s.t 4S.6. ms. ins. 6 12 ins. sp. 132 s. no 60 s. 6S s. ins. s. , too s. s. s. s. 1200 320 V. sp. 0-3 1-4 456 3 V. s. ins. V. s. V. s. 152 ms. ins, 20 0.6 ICO 22.8 760 45 0.6 3 30 V. s. ins. V. s. V. ». ins. ins. s. ins. 40 62.3 3'i 5.8 3-4 6.2 5-8 1.8 374 623 124.6 12.4 9-3 GLOSSARY OF UNUSUAL CHEMICAL TERMS. [The figures in parentheses refer to the pages of this book, where a fuller explanation may be found.] A CTINISM. The chemical effects of light. "^ Aerometer. Hydrometer. .(i3-) .ffirugo. Verdigris. Impure subacetate of copper, .ffithiops. Black sulphide of mercury. HgjS. Alabaster. A light-colored, compact gypsum. CaSOj. (254.) Alchemy. The Arabic name for chemistry, which formerly arose out of the search for the philosopher's stone and elixir of life. Alembic. A form of still or retort, used in sublimation. Alkarsin. Oxide of cakodyl, or cacodylic acid. As(CH3)202H. Alloy. A mixture or compound formed by fusing two or more metals together. Amidon. Starch. (355.) Amorphous. Without a definite crystalline form. Anhydride. An oxide which can combine with the elements of water to produce an acid. Hence, an acid deprived of one or more molecules of water. Anode. The -j- pole of a voltaic circuit. Apple Oil. Valerianate of amyl. Aqua Fontana. Aqua, U. S. P. Aqua Fortis. Crude nitric acid. (172.) Aqua Phagedaenica. Yellow wash. Mercuric hydrate. Aqua Regia. . Nitro-muriatic acid. (173-) Aqua Vitae. Brandy. Argols. Crude cream of Tartar. (239.) Arrack. A spirituous drink made from the juice of the cocoanut tree. Auripigmentum. Orp'iment. Arsenious sulphide. Austral. The south pole of a magnet. Azote. (Fr.) Nitrogen. Azotic Acid. Nitric acid. (172.) 645 646 MEDICAL CHEMISTRY. BALDWIN'S Phosphorus. Fused calcium nitrate, pos- sibly luminous calcium sulphide. Balsam of Sulphur. A solution of S. in olive oil. Barilla. The ashes of sea plants, and Salsola Soda. Basyl. A term applied to an electro-positive radical. Battery. An apparatus for the production of electricity by chemical action. (58.) Baume. The name of the inventor of a hydrometer bearing this name. Bell Metal. An alloy of 6 parts copper and 2 parts tin. Bestuchuf 's Tincture. An ethereal solution of FejClg. Bibron's Antidote. A solution of HgCljjKI, bromine, alco- hol, and water. Bittern, The mother liqjior remaining after extracting NaGl from sea water by evaporation and crystallization. Black Ash. Impure NajCOa, mixed with carbon. Black Drop. Acetum opii. Vinegar of opium. Black Flux. Made by igniting cream of tartar with one-half its weight of nitre ; KNO3. It contains carbon and K2CO3. Black Lead. Plumbago ; a native variety of carbon, used for making lead pencils, crucibles, and stove polish. (199). Black Salts. The ley of wood-ashes evaporated nearly to dry- ness. Black Wash. Contains suboxide of mercury, HgjO. (271.) Bleaching Powder. Chloride of lime. A mixture of chlo- ride and hypochlorite of calcium. (255.) Blende. Native sulphide of zinc. ZnS. (265.) Blue Mass. Pilulse Hydrargyri. Blue Ointment. Unguentum Hydrargyri. Blue Vitriol, or Bluestone. Sulphate of copper. (246.) Bole. An argillaceous earth. Bone Ash. Bone black, or charred bones. (257.) Borax. Biborate of sodium. Tetraborate of sodium, NajB^Oj. (230-) Boreal. The north pole of a magnetic needle. Brass. An alloy of copper and zinc. Brimstone. Roll sulphur. (150.) British Barilla. Black Ash. British Gum. Dextrin. (356.) Bronze. An alloy of copper and tin. Brunswick Green. Oxychloride of copper. Bunsen Burner. A gas burner used for production of heat. It mixes the gas arid air before burning them. GLOSSARY. 647 Burnett's Disinfecting Fluid. Solution of ZnCl2. (164.) Butter of Zinc, Antimony, and Bismuth. Their chlorides. ("'ALAMINE. Impure, native carbonate of zinc. (265.) ^-' Calcareous Spar. Calcite. CaCOj. (258.) Calcedony. A native form of Si02. Calcined Mercury. Mercuric oxide. HgO. Calcining. Igniting a substance in the air, so as to burn off any oxidizable material, or expel volatile products. Calomel. Mercurous chloride. Mild chloride of mercury, Hg^Cl,. (270.) Caloric. Old term for heat. Calorie. The unit of heat used in determining the heat of combination of chemical compounds.' (29.) Camphene. Oil of turpentine. Camphene burning fluid is a solution of turpentine in alcohol. Canton's Phosphorus. Luminous CaS, or luminous paint. Caput Mortuum. The residue left after ignition of FeSO^ or iron pyrites. Impure Fe^Oj. (290) Caramel. Burnt sugar. (349.) Carbolic Acid. Phenic acid. Phenyl alcohol. (409.) Carburet. Carbide. Catalysis. The action of a body in promoting combination or decomposition by its presence, the body itself remaining unchanged. Cathode. The negative pole of a galvanic circuit. Chalk. An amorphous carbonate of lime. (258.) Chameleon Mineral. Permanganate of potassium. Choke- Damp. Carbonic anhydride. COj. (205.) Chrome Green. A mixture of chrome yellow and Prussian blue ; or sesquioxide of chromium. CrjOs. (280.) Chrome Vermilion. Bichromate of lead. PbCrjO,. Chrome Yellow. Chromate of lead. PbCrO^. (222.) Cinnabar. Native red sulphide of mercury. HgS. (269.) Citrine Ointment. Nitrate of mercury ointment. Clay. Impure silicate of alumina. Clay Ironstone. A variety of hematite iron ore. Fefi^. Colcothar. Ferric oxide. FejOj. Rouge ; crocus. Collodion. Solution of gun cotton in alcohol and ether. (358.) Colloids. Jelly-like or non-crystallizable bodies. (74-) Colophony. Common resin, or rosin. (321.) Common Salt. Sodium chloride. NaCl. (225.) 6^8 MEDICAL CHEMISTRY. Condy's Solution. Contains permanganate of potassium. K^Mn^Og. (164.) Copperas. Green vitriol. Crystallized ferrous sulphate. FeSOi.yAq. (288.) Corrosive Sublimate. Mercuric chloride. Bichloride of mercury. (272.) Creapi of Tartar. Acid potassium tartrate. HKCiH^Oo. (239.) Crocus of Antimony, or Crocus Metallorum. Oxysul- phide of antimony. (193O Crocus Martis. Colcothar. FejOs. Crystalloids. Crystallizable bodies, as distinguished from colloids. (74.) Crystals of Venus. Copper acetate. (CuC2H302)j.H20. Cubic Nitre. Sodium nitrate. NaNOg. Cupellation. The process of purifying silver or gold in a cupel or cup made of bone ash. When the alloy is strongly heated in air, the other metals oxidize and the cupel absorbs the oxide, leaving the silver or gold pure. ■p^ECANTATION. The process of pouring off the clear liquid above a sediment. Decoction. An extract of an organic substance, made with boiling water. Decrepitation. The crackling of certain salts when suddenly heated. Deflagration. A rapid and scintillating combustion. It takes place in certain mixtures containing the nitrates or chlorates. Deliquescent. An adjective applied to those substances which attract moisture from the air and liquefy. (75-) Destructive Distillation. Dry distillation, conducted with the object of destroying the substance and producing new ones. (27.) Detonation. Rapid chemical action, accompanied by flame and noise. An explosion. De Valangin's Arsenical Solution. A solution of the chloride. AsCis. Liq. Arsen. Hydrochlor. Dew-point. The temperature at which the moisture of the air begins to deposit. Dialysis. The process of the diffusion of liquids and solutions through membranes. (73.) Dimorphous. Crystallizing in two distinct systems. (74.) GLOSSARY. 649 Displacement. Expelling a fluid from a vessel by another of different density. Dolomite. Magnesium limestone. (264.) Donovan's Solution. Contains the iodides of arsenic and mercury. (183.) Dover's Powder. Compound ipecac, powder; contains opium (i gr. in lo"). Drummond Light. Calcium light. Dry Distillation. The process of subjecting solid .or organic bodies to heat, in a closed retort. Ductile. Capable of being drawn into wire, or rolled out into sheets. Dutch Gold. A species of brass, usually sold in very thin leaves or sheets. Dutch Liquid. Ethene dichloride. C2H4CI2. Dutch White. Impure white lead. PAU de Javelle. A solution of chlorinated potass, or potass. -'-' hypochlorite. KOCl. £ ducts. The proximate principles of which bodies were for- merly supposed to be formed. Effervescence. The rapid escape of gas from a liquid. Efflorescence. The escape of water of crystallization and the consequent crumbling down of the crystal. (75-) Electrode. The pole or wire forming a part of a voltaic cir- cuit. (63.) Electrolysis. Decomposition by means of a strong electric current. (69.) Element. A substance which has never been decomposed. Elixir of Vitriol. Aromatic sulphuric acid. Elutriation. The process of separating the finer and lighter particles of a powder from the coarser, by suspending them in water and pouring off the lighter floating particles with the water. Emerald Green. Schweinfurth green, or aceto-arsenite of copper. See Paris green. Emery. An impure corundum. AI2O3. (277.) Eosine. Tetrabromo-fluorescine. A beautiful, red, artificial coloring matter. Epsom Salt. MgS04.7Aq. (263.) Eremacausis. The slow decay of organic substances in the air. 55 650 MEDICAL CHEMISTRY. Essence of Mirbane. Nitro-benzol. (427-) Essential Oils. Volatile oils. Eudiometer. A graduated glass tube, closed at one end, used for measuring gases. pERMENTATION. (527.) Filter. A porous substance used to separate a solid and liquid by allowing the latter tq pass through, while the former is retained. Fire Damp. Light carbureted hydrogen (Marsh gas), mixed with air. (309.) Fixed Air. Choke damp. CO,. (205.) Flint. An impure variety of silica. SiOj. Flo'wers of Antimony. Oxide of antimony. Flowers of Benzoin. Benzoic acid. (419.) Flowers of Sulphur.' Sulphur sublimatum. U. S. P. (150.) Flowers of Zinc. Oxide of zinc. ZnO. (266 ) Fluorescence. The property possessed by certain bodies,. as quinine salts, of rendering visible the ultra-violet or chemical rays of the solar spectrum. Fluor Spar. Native calcium fluoride. CaF,. (112.) Flux. A material added to ores in smelting, to form an easily fusible slag. Foliated Earth of Tartar. KC2H3O2. Potassium acetate. Fool's Gold. Iron pyrites. Fowler's Solution. Solution of the arsenite of potassium. (185-) French Chalk. Silicate of magnesia. Soapstone; talc. Fructose. Fruit sugar. Fuchsine. Aniline red. Magenta. CjoHigNj. Fuming Liquor of Libarius. Solution of stannic chloride. Fusel Oil. Amylic alcohol. (342.) Fusible Calculus. One composed of a mixture of phosphate of lime, and ammonio-'magnesiuni phosphate. Fusible Metal. Bismuth 2 parts, lead i part, and tin i part. Melts at about 200° F. (""ALENA. Native lead sulphide. (221.) ^^ Galvano- Cautery. A surgical knife heated by a galvanic current. German Silver, An alloy of copper, nickel, and zinc. Glass. An artificial silicate of calcium, sodium, iron, lead etc. Glass of Antimony. Fused trisulphide of antimony. ShzSj. GLOSSARY. 65 1 Glass of Borax. Fused borax. Glauber's Salt. Sodium sulphate. (227.) Glucose. Grape sugar. Now made on large scale from corn starch. (353.) Glucoside. (See p. 472.) Glyceroles and Glycerita. Simple glycerin solutions. Goniometer. An instrument for measuring the angles of crystals. Goulard's Extract, and Cerate. Contain subacetate of lead. Graphine. Carbon deposited in gas retorts. Graphite. Plumbago. Black lead. (199.) Green Vitriol. Copperas. FeS04.7Aq. (288.) Guano. A deposit of excrement of sea fowl. Gypsum. Calcium sulphate. Plaster of Paris. (257.) "LJALOGEN Elements. Haloid Salt. The elements of the chlorine group and their binary compounds, (m.) Harle's Solution. Solution of arsenite of sodiiira. Hartshorn. Ammonia. (165.) Haschisch. Indian hemp. Hepar Sulphuris. Liver of sulphur. Potassium sulphide. Hive Syrup. Compound syrup of squills. Hoffman's Anodyne. Spirit, ^ther. Co. Ether, i pint; alcohol, I pint; ethereal oil, fjvj, Homberg's Pyrophyrus. Is made by igniting potassium, alum, and charcoal. Homologous Series. (304.) Homologues^ (304.) Huxham's Tincture. Compound tincture of cinchona. Hydracid. A binary acid. Contains no oxygen. Hydrate. A compound containing hydroxyl, HO, combined to a positive radical. Hydrochloride. A compound of HCl, fortiied by union of the whole molecule by synthesis; as compounds with the alka- loids. Hydroxide. Same as a hydrate. Hygrometer. An instrument for the determination of the relative amount of moisture in the air. TOE Vinegar. Glacial acetic acid. (395.) Incandescence. The glow of a highly heated body. Incineration. The reduction of a substance to ashes by burning. 652 MEDICAL CHEMISTRY. Incompatible. Incapable of being mixed without chemical change. Infusion. An extract of an organic substance, made by pouring hot water upon it and allowing it to stand for some hours, (146.) Inosite. Muscle sugar. (355-) Ion. A body going to the positive (anode) or negative (cathode) pole of a galvanic battery during electrolysis. Iron Pyrites. Native sulphide of iron. Fool's gold. Isinglass. A variety of gelatin, or fish glue. Sometimes erroneously applied to mica. Ivory Black. Animal charcoal, made by distilling ivory scraps ; is now generally applied to bone black. JAMES' Powder. Antimonial powder. Japan Black. A varnish composed of asphaltum, turpen- tine, linseed oil, and umber. Jesuits' Powder. Powdered cinchona bark. T^AOLIN. A pur-e white clay. Kelp. Ashes of sea weeds; used as a source of iodine and carbonate of sodium. Kermes' Mineral. SbjSs. (194.) King's Yellow. Orpiment. AsjSs. Kyan's Disinfectant. Solution of HgClj. T ABARRAQUE'S Disinfecting Liquid. Solution of hypochlorite of sodium or chlorinated soda. (231.) (165.) Lac Sulphuris. Precipitated sulphur. (151.) Lacquer. A varnish used for brass, etc. Lactin — Lactose. Sugar of milk. (351.) Lady Webster Pill. Pill of aloes. Lake. An organic coloring matter precipitated with aluminium hydrate. Used as pigments. Lampblack. The soot of burning turpentine. (200.) Lana Philosophica. Oxide of zinc. (267.) Lapis Infernalis. Lunar caustic. AgNOj. Laughing Gas. Nitrous oxide. N^O. Dentists' gas. (168.) Lead Water. Diluted Goulard's Extract, containing subace- tate of lead. (221.) Ledoyen's Disinfecting Liquid. Solution of nitrate of lead. (164.) Levigation. The reduclion of a substance to an impalpable powder, by rubbing on a slab, with sufficient water to form a paste, with a flat pestle called a muller. GLOSSARY. 653 Lime. CaO. (256.) Limestone. A native carbonate of linne. (258.) Litharge. PbO. Semi-vitrified oxide of lead. (219.) Lithic Acid. Uric Acid. (443.) Liver of Sulphur. Potass, sulphuret. K2S. (238.) Lixiviation. The separation of the soluble portions of a sub- stance by causing water to filter through it. (146.) Loadstone. The native magnetic oxide of iron, or magnetite. A magnet. (290.) Lugol's Solution. Compound solution of iodine. Iodine held in solution by Ki. (121.) Lunar Caustic. Nitrate of silver. AgNog. (251.) Lute. An adhesive mixture for closing the joints of apparatus, to prevent the escape of vapors, etc. lV/[ACERATION. The long-continued soaking of a sub- stance in water at common temperatures. (146.) Macquer's Salt. Potassium arseniate. Magendie's Solution. Morph. sulphate, gr. xvj; water, j3j. Magistery of Bismuth. Subnitrate. Magma. A pasty mass. Magnesia Alba. Magnesium carbonate. (264.) Malleable. Capable of being worked under the hammer. Marble. Nearly pure native carbonate of lime. (258.) Marine Acid. Muriatic acid. Hydrochloric acid. HCl. (116.) Martial .^thiops. Fefi^. Magnetic oxide of iron. Massicot. Amorphous oxide of lead. PbO. Powdered lith- arge. (219.) Matrass. A glass vessel with a long neck, or a tube sealed at one end. Used for heating dry substances. Menstruum. A solvent, or medium of chemical reaction. Mercaptan. An alcohol in which O is replaced by sulphur. Metalloid. Non-metal. (104.) Metameric Bodies. The same as isomeric. (306.) Microcosmic Salt. NaNH^HPOi. Milk of Lime. Whitewash. (256.) Milk of Sulphur. Precipitated sulphur. Mineral Water. Water charged with carbonic acid ; also natural water holding medicinal substances in solution. (145.) Mineral Yellow. Oxychloride of Lead. Minium. Red oxide of lead. 2PbO.Pb02. (219.) Molecule. (77.) 654 MEDICAL CHEMISTRY. Monsel's Salt. Subsulphate of iron. (290.) Mordant. A substance used to fix colors on fabrics. Mosaic Gold. Brass. Mountain Blue. Azurite. Native basic carbonate of copper. Mountain Green. Malachite. A native basic carbonate of copper. (247.) ^ ^^ Mulberry Calculus. Calcium oxalate. CaCjOj. Muriate. A chloride. Muriatic Acid. Hydrochloric acid. (116.) TSJAPHTHA. A light hydrocarbon obtained from petro- leum, and boiling at about 80° to 105° C. (311-) Natron. Native carbonate of sodium. Neutral. Without action on test paper. Neither acid nor alkaline. Neutral Mixture. Solution of citrate of potassium. Nitre. Saltpetre. K.NO3. (.236.) Normal Salt. Neither acid nor basic. r~)BSIDIAN. Volcanic glass. ^^^ Ochre. A native mixture of clay and ferric oxide, used as a paint. Oil of Vitriol. H^SO^. Sulphuric acid. (155.) Oil of Wine. Ethyl sulphate. (QH5),S04. Oreide. A species of brass resembling gold, and used for jewelry. Orpiment. Arsenious sulphide. AsjSj. (183.) Ortho-acid An acid in which each bond of the kernel is united to hydroxyl. (OH.) Osmosis. The diffusion of liquids through porous septa. See Dialysis. (73.) Ox-acid.- A ternary acid containing oxygen. (91.) pACKFONG. A variety of German silver. Paris Green. Impure Schweinfurth green. Aceto-arsen- ite of copper. (247.) Particle. A minute portion of matter. Pearl.Ash. Impure carbonate of potassium. (237.) Pearl Powder. Subnitrate, or oxychloride of bismuth. (BiO NO3 or BiOCl.) Pearl White. BiONOs, or BiOCl. Pearson's Salt. Arseniate of sodium. Nas^sOi. GLOSSARY. 655 Pewter. Analloy of variable composition. Usually composed of tin, lead, copper, and antimony, or zinc. Pinchbeck Gold. A species of brass. Plaster of Paris. Calcium sulphate. Calcium gypsum. (2S7-) Platinum Black, and Sponge. Finely divided platinum. (294-) Plumbago. Native carbon. Graphite. (199.) Potash. Impure carbonate of potassium. Potassa. Oxide or hydrate of potassium. Powder of Algaroth. Oxychloride of antimony. (193.) Precipitate. An insoluble substance, formed on bringing two or more substances together in solution. Precipitatum Per Se. Mercuric oxide. HgO. Made by heating mercury to near its boiling point until it oxidizes. Preston Salts. Carbonate of ammonia, flavored with some essential oil. Prussian Blue. Ferric ferrocyanide. (214.) Prussic Acid. Hydrocyanic Acid. (505.) Pseudomorph. A mineral crystallized in the form that be- longs to another mineral. Puce-oxide of Lead. Lead peroxide, or brown oxide. Purgative Mineral Water. Liq. magnes. citrat. Purple of Cassius. A pigment produced by treating chlo- ride of gold with a solution of stannous chloride. (253.) Putty. Composed of whiting and linseed oil. Putty Powder. Stannic oxide. Pyrites. Native sulphide of iron. Pyroxilic Spirit. Wood alcohol. Methyl alcohol. (336.) Pyroxylin. Gun cotton. Trinitro-cellulose. (358.) QUANTIVALENCE. Quantity of combining power; applied to atoms. (See Equivalence.) Quartz. SiO^. (214.) Quevenne's Iron. Ferrum redactum. (287.) Quicklime. Caustic lime. CaO. (255.) Quicksilver. Mercury. (269.) "P ADICAL. An atom, or group of atoms, forming the basis , of a series of compounds. (88.) Radical Vinegar. Glacial acetic acid. Realgar. Red .sulphide of arsenic. (184.) Red Precipitate. Red oxide of mercury. HgO. (273.) 656 MEDICAL CHEMISTRY. Red Prussiate of Potash. Ferricyanide of potassium. (214-) Red Tartar. Argol. (239.) Regulus of Antimony. Metallic antimony. Roche, and Roman Alums. Are varieties of potassium alum. Rochelle Salt. Tartrate of potassium and sodium. (240.) Rock Crystal. Quartz. SiOj. (214.) Roman Vitriol. Sulphate of copper. CuSOi. Rouge. Ferric oxide in fine powder. FejOa- Ruby. Native AI2O3, of a beautiful red color. (278.) Rust. Ferric oxide ; generally containing some ferric hydrate. C ACCHARUM Batumi. Acetate of lead. (348.) Safety Lamp, A lamp inclosed in wire gauze, to prevent explosions of explosive gases in mines, cellars, etc. Sal .ffiratus. Potassium bicarbonate. Sal Alembroth. Double chloride of mercury and ammonium. (272.) Sal Ammoniac. Ammonium chloride. (241.) Sal Diureticus. Potassium acetate. Sal Enixum. Potassium bisulphate. Sal Mirabile. Sodium sulphate. Sal Perlatum. Sodium Phosphate. Sal Prunella. Fused nitre. KNO3. Sal Volatile. Ammonium carbonate. Salt of Lemon and Salt of Sorrell. Potassium binoxalate. (239-) Salt of Phosphorus. Microcosmic salt. Salt of Saturn. Acetate of lead. (221.) Salt of Tartar, Pure potassium carbonate. (237.) Saltpetre. Potassium nitrate. (236.) Sapphire. A native form of AI2O3. (278.) Scheele's Green. Arsenite of copper. (185.) Schlippe's Salt. Sodium sulphantimoniate. NasSbSj. Schweinfurth Green. Copper aceto-arsenite. (247.) Seidlitz Powder. A mixture of sodium bicarbonate and Rochelle salt in one paper and tartaric acid in another. Seignette's Salt. Rochelle salt, KNaQH.Oe. (240.) Sienna. A native red pigment. An impure oxide of iron. Sizing. A gelatinous mixture put into paper or cloth, to fill up the pores. Slag. The fused impurities from smelting of ores. (286.) GLOSSARY. 65 7 Smalt. Glass colored blue by oxide of cobalt and powdered. Smelting. The process of recovering the metals from their ores. Soapstone. Talc. (262.) Soda Ash. Crude sodium carbonate. (228.) Soda Saltpetre. Sodium nitrate. NaNOj. (230.) Soda \A^ater. Water artificially charged with CO2 under pressure. Solder. An alloy of tin and lead. Soluble Glass. See Water Glass. (215.) Soluble Tartar. Neutral potassium tartrate. (239.) Speculum Metal. An alloy of copper and tin. Speiss. Impure, fused nickel arsenide. Spelter. Commercial zinc. Spermaceti. A fat obtained from the sperm whale. Spirit of Hartshorn. Spirit of ammonia. Solution of am- monia in alcohol. Spirit of Mindererus. Solution of ammonium acetate. (243.) Spirits of Nitre. Nitric acid. (364.) Spirit of Salt. Muriatic acid. (116.) Spirit of ^A^ine. Alcohol. Steinbuhl Yellow. Barium chromate. BaCrO,. Substitution. The displacement of an atom in a molecule by another atom of a different kind. Sugar of Lead. Lead acetate. (221.) ' Sulphuret. Sulphide. Sulphuric iEther. Ethylic ether. CiHioO. (362.) Sulphur Vinum. Impure sulphur. Horse brimstone. 'X'AL.MI Gold. An alloy of copper and aluminium. Tartar Emetic. Antimony and potassium tartrate. (240.) Tasteless Purging Salt. Sodium phosphate. Th^nard's Blue. A compound of the oxides of aluminium and cobalt. Tincal. Native borax. NajB^O,. C230.) Tincture. A solution in alcohol. When in ether, it is called an ethereal tincture. Tombac. A kind of brass. Tournesol. Litmus. Trituration. Rubbing in a mortar. Trona. Native sodium carbonate. Turnbull's Blue. Ferrous ferricyanide. (214.) 56 658 MEDICAL CHEMISTRY. Turner's Cerate. Calamine cerate. Turner's Yellow. Lead oxychloride. Turpeth Mineral. Yellow sulphate of mercury. (274.) Tutty. Impure zinc oxide. Type Metal. An alloy of lead and antimony (218). T JLTRAMARINE. Lapis lazuli. A compound of alumi- nium sodium silicate with sodium sulphides. A beautiful blue pigment. It is now prepared artificially, as well as a green, red, and violet variety. Umber. A native silicate of aluminium, with oxides of iron and manganese. Used as a brown paint. "\/"ALENCE of Atoms. Quantity of combining power. Vallet's Mass. FeCOj made into a pill mass. Varec. Kelp. Ash of sea weeds. Verd Antique. Precious serpentine. Verdigris. Impure copper subacetate. (247.) Verditer. Basic copper carbonate. Vermilion. Artificial mercuric sulphide. HgS. (274.) Vitriolic Acid. Sulphuric acid. (155.) V\7ATER Glass.' Soluble glass. Sodium silicate. (215.) White Arsenic. Arsenious oxide. ■White Lead. A basic lead carbonate. (220.) White Precipitate. Ammoniated mercury. Mercur-amido- gen chloride. NHjHgCl. (272.) White Vitriol. Zinc sulphate. (267.) Whiting. Prepared chalk. CaCOa. White clay, often sold for whiting. Wood Naphtha and Wood Spirit. Methyl alcohol. (336.) ^Vood Vinegar. Pyroligneous acid. Impure acetic acid. (395-) "VELLO^V Prussiate of Potash. Potassium ferrocyanide. ^ (2I3-) Yellow Wash. Made by adding corrosive sublimate to lime water. It forms mercuric oxide. (272.) yAFFRE. Impure cobalt oxide. Zinc White. Zinc oxide. Used as a paint. (266.) Zymosis. The peculiar action caused by a ferment. NDEX. A BSORPTION spectra, 37 •'*• Acetamid, 429 Acetanilid, 430 Acetin, 431 Acetone, 386 Acetonuria, 603 Acetal, 384 Acetphenetidin, 432 Acetylenes, 312 Acetylid, 312 monosodium, 312 disodjum, 312 silver, 312 Acid, abietic, 321 acetic, 302, 393, 395 acetic, glacial, 395 aconitic, 505 albumin, 482, 559 amido-caproic, 439 amido-formic, 440 amido-oxyphenyl-propionic, amido-glutaric, 440 amido-succinic, 440 amido-sulpho-lactic, 440 antimonic, Z94 arable, 359 aspartic, 440 arsenic, 184, 282 arsenious, 184, 503 benzoic, 419 benzamidacetic, 437 bismuthic, 196 boracic, 276 bromic, 148 butyric, 397 caffeetannic, 475 capric, 373 caproic, 373 caprylic, 373 carbamic, 440 carbazotic, 414 439 Acid, carbolic, 409, 502 carbonic, 209 catechutannic, 475 chloric, 148 chlorous, 148 cholic, 449 chromic, 280 citric, 407 cresylic, 410 cresotic, 412 cyanic, 213 dextrotartaric, 406 diatomic, 401 diacetic, 604 dichloracetic, 395 ethylsulphonic, 388 . ethylsnlphuric, 362, 365 excretoleic, 565 eugenic, 413 gaduic, 371 gallic, 421 gallotannic, 474 glutaric, 440 glycero-phosphoric, 346 glycero-sulphuric, 346 glycocholic, 449 glycolic, 401 hippuric, 437, 612 hydriodic, 121 hydrobromic, 119 hydrochloric, 115 hydrocyanic, 210, 505 hydrofluoric, 112 hydrosulphuric, 152 hydroxypropionic, 401 hypobromous, 148 hypochlorous, 148 hyponitrous, 169 hypophosphorous, l8l hyposulphurous, 154 indigotin sulphonic, 448 659 66o INDKX. Acid, indoxyl-sulphuric, 447, 448 iodic, 148 isobutyric, 397 kinotannic, 475 lactic, 393, 401,515 tests for, 403 Isevotartaric, 406 litliic, 444 malic, 405 mannitic, 347 margaric, 399 meconic, 408 mesotartaric, 406 metaboric, 277 metantimonious, 194 metaphosphoric, 180, 594 irietatartaric, 406 muriatic, 116 nitric, 172 in air, 162 nitric, fuming, 173 tests for, 173 physiological effects, 174 nitro-hydrochloric, n8 nitrous, 170 in air, 162 oleic, 399 organic, 392, 558 orthophosphoric, 179 orthosulpfauric, 156 osmic, 295 oxalic, 403 oxaluric, 445 oxybutyric, 403, 604 oxybenzoic, 420 oxytoluic, 412 oxysuccinic, 405 palmitic, 398 parabanic, 445 paralactic, 402 pectin, 360 perbromic, 148 perchloric, 148 periodic, 148 phenic, 409 phenylsulphuric, 564 phosphomolybdic, 451 phosphoric, 179 glacial, 180 phosphorous, 178 phosphotungstic, 596 Acid, picric, 452, 414 plumbic, 220 propionic, 395 . prussic, 505 pyroantimonic, 195 pyrogallic, 418 pyrophosphoric, 180 pyrotartaric, 406 quercitannic, 475 quinic, 475 quinotannic, 475 racemic, 406 saccharic, 347 salicylic, 303, 420 salicylous, 419 salicylsulphonic, 422, 594 sarcolactic, 402 silicic, 215 sozolic, 389 stearic, 399 succinic, 404 sulphocarbolic, 421 sulphocarbonic, 210 sulphonic, amido-ethyl, 437 ortho-phenyl, 421, 389 sulphuric, 132, 155, 452 fuming, 157 Nordhausen, 1.57, 288 sulphurous, 154 sulphydric, 152 sylvic, 321 tannic, 474 tartaric, 406 taurocholic, 449 tetraboric, 277 trichloracetic, 382, 594 tri-oxy-benzoic, 421 tungstic, 282 uric, 443, 607, 623 uric, detection of, 444 valerianic, 398 valeric, 398 Acids, amido, 440 aromatic, 419 atomicity of, 515 basicity of, 91, 393 biliary, 449, 605 tests, 449 definition, fatty, 394 oxacids, 91 INDEX. 66 1 Acids, organic, 392 . dibasic, 403, 405 moDobasic, 401, 403 tribasic, 407 sulpho, 91 tbionic, 154 vegetable, 502 Aconitine, 460 Actinic rays, 39 Actinism, 39 Addition products, 327 Adenin, 447 . Adhesion, 14 Adipocere, 398 Adracanthin, 359 Air, 160 gases in, 162 Albumin, egg, 480, 592 estimation of in urine, 594 serum, 479 tests for, 592 vegetable, 479, 491 Albumins, derived, 478, 479 native, 478 Albuminates, acid, 478 alkali, 483 Albuminometer (Esbach's), 594 Albuminuria, accidental, 597 Albumose, 479, 486, 492, 595 Alcohol, absolute, 337, 505 estimation of, 339 amyl, 343 aromatic, 418 benzylic, 418 butyl, 342 «ryl, 343 cetyl, 343 commercial, 338 diatomic, 330, 344 ethene, 344 ethyl, 301, 337 heptyl, 336 hexyl, 336 melissyl, 343 menthyl, 318 methyl, 336 octyl, 336 phenyl, 409 propyl. 342 physiological action, 338 Alcohols, hexatomic, 346 Alcohols, monatomic, 335 primary, 335 secondary, 335 table of, 336 tertiary, 335 tetratomic, 346 triatomic, 335, 344 Aldehyde, ethyl or acetic, 381 anisic, 419 benzoic, 418 cinnamic, 382, 419 cuminic, 382,419 formic, 380 propyl, 342 salicylic, 382, 419 trichlor, 382 vanillic, 382, 419 Aldehydes, 379 Algaroth, powder of, 193 Ale, 340 Algin, 360 AUantoin, 445 Alizarin, 326 Alkali' albumin, 483 Alkaline earths, metals of, 253 phosphates, 5 1 7 Alkaloids, 450 cadaveric, 466 color reactions, 455 natural, 450 nomenclature, 451 opium, 464 properties, 450 putrefactive, 466 reagents for, 445 separation of, 456 table of, 458 AUolropism, 115 Alpha-naphthol test, 601 Alum, ammonium, 501 burnt, 278 chrome, 279 ferric, 279 manganese, 279 potassium, 278 Alumina, 278 Aluminates, 277 Aluminite, 278 Aluminium, 277 bronze, 277 chloride, 277 662 INDEX. Aluminium hydroxide, 278 oxide, 278 sulphate, 278 and ammon. sulphate, 278 Amalgam, 269 Amalgamation, 60 Amber, 321 Amethyst, 214 Amids, 423, 428 acid, 423 Amins, 422 preparation of, 424 primary, 1 secondary, >■ 422 tertiary, J Ammonia, 141, 161, 165 action on economy, 243 composition, 166 tests, 167 Ammoniacum, 321 . Ammonias compound, 450 Ammonio-ferrous sulphate, 288 Ammonio-magnesium phosphate, 264, 610 Ammonium, 241 acetate, 243 benzoate, 243, 420 bromide, 241 carbamate, 441 carbonate, 242, 517 chloride, 241 compounds, 241 hydroxide, 198, 242 iodide, 241 molybdate, 282 muriate, 241 nitrate, 243 phosphate, 243 purpurate, 446 sulphate, 243 sulphide, 243 sulphocyanate, 213 sulphydrate, 162, 243, 268 urate, 623 valerianate, 243 Ampere, 56 Ampere's law, 20, 80 Amygdalin, 211, 418, 472 Amyl acetate, 366 alcohol, 342 nitrite, 366 Amylene hydrate, 343 Amyloid matter, 479 Amylopsin, 525, 561 Amyloses, 355 Amylum, 355 Anaesthetics, 505 Anhydride, 154 Analysis, toxicological, 187 Anglesite, 220 Anhydride, boric, 276 carbonic, 205 chlorous, 148 hypochlorous, 147 molybdic, 282 nitric, 171 nitrous, 170 plumbic, 219 silicic, 215 sulphuric, 155 sulphurous, 154 Anhydrite, 257 Anilids, 430 Anilin, 427, 505 colors, 427 derivatives, 429 Animal synthesis, 509 Annatto, 498 Annidalin, 414 Anode, 63 Anthracene, 326 Anthra-quinoue, 327 Antiarin, 472 Antifebrin, 430 Antimony, 192 and potass., tartrate of, 195 butter of, 193, 503 chloride, 193, 503 crocus of, 193 glass of, 193 hydride, 192 oxide, 194, 503 oxychloride, 193 pentachloride, 193 pentasulphide, 194 physiological action of, 195 protochloride, 193 sulphate, 194 sulphide, 194 tartrated, 240 trichloride, 193 trioxide, 194 INDEX. 663 Antimony, trisulpbide, 193 vermilion, 194 wine of, 503 Antipeptone, 488 Antipyrin, 432 Antiseptics, 163, 527 Apomorpliine, 502 Appendix, 627 Aqua, 146 ammonise, 166 fort., 166 chlori, 114 fortis, 172 regia, 173 Arabin, 359 Arabinose, 359 Arbulin, 472 - Archil, 416 Argentum, 249 Argol, 406 Aristol, 414 Aromatic series, 322 Arsenic, 182, 503 disulphide, 184 fluoride, 183 iodide, 183 oxides, 185 pentasulphide, 184 poisoning, 185 tribromide, 183 trichloride, 183 trisulphide, 183 white, 503 Arsine, 182 Asafcetida,.32l Asaprol, 389 Asbestos, 262 Asepsis, 163 Aseptol, 389 Assimilation, 530, 543 Atmosphere, 160 Atomic weight, 83 Atomicity, 393 Atoms, characteristic groups of, < combining power, 84 definition of, lo, 83 equivalent of, 84, 89 Atropinae sulphas, 460 Atropine, 460 Aurates, 253 Auric, chloride, 253 Auric oxide, 253 Aurous chloride, 252 oxide, 253 Avogadro's law, 20, 80 Azurite, 244 ■DACTERIUM lactis, 401 ^ Baking powders, 239, 240 Balsam copaibse, 321 Peru, 322 Balsams, 319 Bands, dark, 36 Barite, 261 Barium, 260 carbonate, 261 chloride, 260 nitrate, 261 oxide, 260 peroxide, 260 physiological effects of, 261 sulphate, 261 Barometer, 17 Baryta, 260 Base, 91 Bases, artificial organic, 434 natural organic, 450 organic, 423, 434 pyridin, 435 Basicity of acids, 91, 393 Ba'^sorin, 359 Batteries, care of, 60 polarity of, 60 storage, 61 Battery, Bunsen, 58 Callaud, 59 Grove, 58 Leclanche, 59 Beef tea or extracts, 547 Beer, 340 Belladonna, 506 Benzene, 324, 326 dinitro, 324 hexachloride, 324 nilro, 324 Benzoates, 419 , Benzoic aldehyde, 3S2 • Benzoin, gum, 419 Benzol, 324 Benzo-purpurin, 554 Benzosol, 417 664 INDEX. Benzoyl chloride, 606 Berthelet's laws, 99-101 Beryllium, 253 Bessemer steel, 287 Beverages, 339 Bile, 562, 60s composition of, 562 toxic effects of, 563 Biliary coloring matters, 495 in urine, 495, 605 compounds, 494 Bilicyanin, 495 Bilifulvin, 495 Bilifuscin, 495 Bilibumin, 495 Biliphaein, 495 Biliprasin, 495 Bilirubin, 495 hydro, 495 Biliverdin, 495,496 Bismuth, 196 carbonate, 197 chloride, 196 citrate, 180, 198 nitrate, 196 oxide, 196 subcarbonate, 197 subnilrate, 197 physiological action of, 198 test, 600 tests, 198 Bites, 507 Bitumen, 311 Biuret reaction, 478 Black, wash, 271 Blast furnace, 286 Bleaching powder, 25S , Blende, 265 Blood, in CO^ poisoning, 208 crystals, 493 dragons, 320 in urine, 597, 616, 617 tests for, 597 Blue stone, 246 vitriol, 246 Bodies, organise containing nitrogen, 4^2 Body, deBnition of, 10 Boiling point, 26 Bone ash, 257 black, 2CO Bone phosphate, 257 Borax, 230, 276 Boroglyceride, 277 Boron, 276 chloride, 276 fluoride, 276 Brandy, 339 Braunite, 283 Brazil wood, 498 Brighton green, 248 Brimstone, 150 British gum, 356 Bromides, tests for, 120 Bromine, 118, 507 Bromoform, 333 Bromol, 413 Brucine, 460, 506 Bunsen's battery, 58 Burnett's fluid, 164 Butane, 310 Butene, 312 Butter, 373. 534, 5^8 cacao, 372, 373 of antimony, 193 Butterine, 373 Butyric acid, 397 pADAVERlN, 468 ^ Cadmium, 268 chloride, 268 compounds of, 268 hydroxide, 268 iodide, 269 oxide, 268 sulphate, 268 sulphide, 269 Caesium, 240 Caffeine, 461 Calamine, 265 Calcium, 254 bromide, 254 . carbonate, 258, 518, 612 chloride, ^54 sulphide, 259 hydroxide, 256 hypochlorite, 255 hypophosphis, 259 iodide, 254 light, 256 oxalate, 258, 609 INDEX. 66s Calcium oxide, 255 phosphates, 257, 612 acid dicalcium monocalcium precipitatus tricakic or bone physiological eiTects of, 259 silicate, 256 sulphate, 257, 612 Calculi, analysis of, 623 Calculus, compound, 622 fusible, 622 mixed, 622 mulberry, 622 simple, 622 Callaud's battery, 59 Calomel, 270 Calorie, 29, 535 Calorimeter, 535 Calx, 255 cblorata, 255 sulphurata, 259 Camphor, 317 Borneol or Borneo, 317 common Japan, 317 dibromide, 317 monobromated, 317 salol, 367 Camphors, 317 Cane sugar, 348 Cantbaridin, 319 Caoutchouc, 314 Caput mortuum, 290 Caramel, 349 Carat, 252 Carbamins, 391 Carbamid, 441 Carbinol, 342 Carbohydrates, 347, 513 Carbon, 199 amorphous, 200 and hydrogen, 296 and nitrogen, 210 qualitative examination of, and oxygen, 204 and sulphur, 209 detection of, 297 dioxide, 161, 507 in air, 161 physiological effects, 206 Carbon dioxide, tests for, 208 disulphide, 162, 209 gas retort, 200 monosulphide, 210 monoxide, 204, 507 nuclei, 303 suboxide, 204 Carbonates, 209 Carmine, 498 Carnallite, 234 Carnelian, 214 Carnin, 446 Carvacrol, 413 Casein, 483, 567 determination of, 492 Caseinogen, 483, 484 Caseins, vegetable, 492 Cassiterite, 215 Castorin, 320 Casts, blood, 618 epithelial, 618 fatty, 619 granular, 619 hyaline, 618 mucous, 620 oil, 619 renal, 616 waxy, 620 Calaphoresis, 68 Cathode, 63 Caustic alkalies, 223 poisoning by, 231 lunar, 251 potash, 235 Caustic soda, 226 Celestite, 260 Cell, Bunsen's, 58 galvanic, theory of, 55 Groves', 58 Leclanche, 59 Cellulose, 358 Cement, 256 Cerasin, 360 Cerebrose, 355 Cerium, 222 oxalate, 223 Cerussite, 217, 220 Chain, open, 303 closed, 303 Chalcocite, 244 Chalcopyrite, 244 666 INDEX. Chalk, 258 prepared, 258 Charcoal, 200 animal, 200 official preparations of, 201 wood, 200 Charge, 45 Charles, law of, 19 Chemical affinity, 14 elements, definition of, 77 elements, table of, jS equations, 98 notation, 85 physics, 16 reactions, 98 rules forj^ 100 symbols, 85 Chemicals, solubility of, 638 Chemism, 14 Chemistry, definition of, 9 inorganic, 104 organic, 296 physiological and clinical, 509 theoretical, 77 Chitin, 491 Chloral, 382, 505 action on economy, 383 alcoholate, 383 amid, 384, 429 butyl, 383 chloroform, 332 croton, 383 detection of impurities, 333 foramid,'384 habit, 383 hydrate, 383 imid, 384, 429 menthol, 384 urethane, 384 Chlohydrins, 345 mono, 345 di, 345 Chloric tetroxide, 148 Chlorococcus, 564 Chloride of lime, 255 Chlorides in urine, 585 estimation of, 585 Chlorine, 113, 507 oxides, 147 Chloroform, 331, physiological effects of, 332 Chloroform vapors, 505 Chlorophyll, 498, 510 Cholepyrrhin, 495 Cholesterin, 371, 562, 564 Cholin, 426 Chondrin, 489, 490 Chromophanes, 496 Chromates, 281 toxicology, 281 Chrome, alum, 279 green, 280 iron, 279 yellow, 221 Chromic anhydride, 280 chlorides, 280 oxide, 280 . trioxide, 251 Chromite, 281 Chromium, 279 oxides, 280 sulphates, 281 toxicology of, 281 Chromous chloride, 280 hydroxide, 280 Cinchona, 463 Cinchonidine, 453, 458 Cinchonine, 463 Cinnabar, 269 Citrates, 407 Classification of elements, 104 Clay, 214 Coagulation, 476 Coal, 201 anthracite, 201 bituminous, 201 brown, 201 cannel, 201 gas, 202 lignite, 201 tar, 203 wood, 201 Cobalt, 293 compounds of, 293 Cobaltic compounds, 293 Cobaltous compounds, 293 chloride, 293 hydrate, 293 nitrate, 293 oxide, 293 sulphate, 293 sulphide, 293 INDEX. 667 Cobaltite, 293 Cocaine, 463 Cocculus Indicus, 505 Cochineal, 498 Codeine, 454, 458 Cohesion, 14 Coil, induction, 64 Coke, 200 Colchicine, 463 Colchiceine, 463 Colcothar, 290 Colic, painters', 222 Collagen, 489 Collodion, ^^S flexible, 358 styptic, 358 Colloids, 74 Colophene, 313 Colophony, 321 Coloring matters, vegetable, 497 Colors, table of, 33 Combining power, 83, 84 Combustion, 124 moist, 140 Compound body, 90 Compounds, binary, 90 Concretions, urinary, 614 Condiments, 547 Conductors, resistance of, 6l Conglutin, 492 Coniferin, 472 Coniine, 457 Constitution, 305 Convolvulin, 472 Convulsives, 506 Copal, 321 Copper, 244 acetates, 247 ammonio-sulphate, 246 arsenite, 247 basic acetates, 247 carbonates, 247 physiological action, 248 pigments, 248 poisoning, 248 pyrites, 244 stone, 244 sulphate, 246 Copperas, 288 Cordials, quieting, 505 Core, influence of, 67 Corpuscles, 466 Corrosive sublimate, 272 Corundum, 277 Cotton, gun, 358 Cream of tartar, 239, 406 Creasote, beechwood, 41 1 Creatin, 438 Greatinin, 369, 438 Creosote, 502 Cresol, 410 Cresotates, 412 Critical temperature, 206 Crocin, 498 Crocoisite, 217 Crocus, red, 290 Crystallin, 481 Crystallization, 73 water of, 75 Crystallography, 73 Crystalloids, 74 Crystals, forms of, 75, 76 system of, 75 Cudbear, 418 Culinary paradox, 26 Gupric bromide, 246 carlranates, 247 chloride, 245 compounds, 245, 246 hydroxide, 246 oxide, 246 sulphate, 246 tetrammonium sulphate, 246 Cuprite, 245 Cuprous compomiib, -245 chlorides, 245 iodides, 245 oxides, 245 sulphides, 245 Currents, extra, 65 Faradic, 65 induced, 63 interrupted, 54 local, 60 secondary, 65 thermo-electric, 68 Cyanides, 211 compound, 213 iso, 391 tests for, 212 toxicology, 211 Cyanogen, 210 668 INDEX. Cyclops, 143 Cyslin, 440 Cymogene, 311 DAMMAR, 320 Daphniae, 143 Daturin, 460 Decimal system, 14 Decoction, 146 Definite proportion, law of, no Deliquescent, 75 Deliriants, 506 Density, 1 1 Deodorizers, 163 Deoxidation, no Deposits, crystalline, 607 organized, 614 table for analysis of, 621 Depressants, 506 Desmids, 143 Detritus, 620 Dew point, 161 Dextrin, 356 in urine, 603 Dextrorotatory, 44 Dextrose, 353 Diabetes mellitus, 599 Dialyser, 73 Dialysis, 73 Diamins, 428, 606 Diamin, telramethyl, 469 Diamond, 199 Diastase, 519, 526 pancreatic, 5 > 9, 5^ ' Diazo reaction, 606 Dicalcium phosphate, 257 Didymium, 38 Diets, 531 approximate principles of, 531 exchange of material in, 531 Diffusion, 72 of gases, 22 of liquids, 72 Graham's law of, 23 Digestion, 146, 530, 541, 549 artificial, 541 Digitalein, 473 Digitalin, 473 Digitalis, 506 Digitoxin, 473 Dihydro-phenol, 415 Dimorphism, 74 Diphenyl, 325 Disinfectant, Lenande's, 164 Disinfectants, 163 commercial, 165 Distillation, 27, 320 destructive, 27 fractional, 27 Dolomite, 262, 264 Donne's test, 599 _ Drummond light, 256 Dualine, 346 Dulcite, 347 Dulcitol, 347 Dulcose, 347 Duretin, 466 Dynamite, 346 ■CBONITE, 314 A-* Efflorescence, 75 Elastin, 490 Electrical charge, 65 current or circuit, 53 induction, 66 tension, 54 units, 54 Electron, 44 Electricity, 44, 51 effects of, 68, 70 extracurrent, 65 frictional, 45 machine, 48 Toepler-Holtz, 48 magneto-, 67 resistance of conductors of, 61 secondary or induced currents, 65 thermo-, 68 Electrics, 44 Electrodes, 63 Electro-metallurgy or plating, 70 Electro-motive force, 54 Electronegative atoms, 83 Electro positive atoms, 83 Electrolysis, 6g Elements, chemical, definition, 77 classiBcation of, 104 non-metallic, 104 Elemi, 320 Emery, 277 INDEX. 669 Emetics, 501 Emulsin, 472, 522 feiment, 519 Energy, 17 muscular, 548 vegetable, 509 Enzymes, 519 Epithelium cells, 615 Epsom salt, 263 Equations, 98 Equivalence, 85 table of, 89 variation in, 87 Esbach's albuminometer, 594 Esculetin, 473 Esculin, 473 Eserine, 465 Essence of mirbane, 427 Essences, 367 fruit, 367 Esters, 363 Ethane, 309 Ether, 360 acetic, 364 ethyl, 362 luminiferous, 31 nitrous, 364 sulphuric, 362 Ethers, 360 compound, 361, 363 formation of, 361 haloid, 360 mixed, 360 of glyceryl, 368 of paraffine series, 361 simple, 360 Elhine, 312 Ethyl acetate, 364 alcohol, 337 bromide, 334 butyrate, 366 carbamate, 365 chloride, 334 mercaptol, 388 nitrate, 363 nitrite, 364 oxide, 362 sulphate, 365 Eucalyptin, 318 Eucalyptol, 317 Eugenol, 413 Eugenol benzoyl, 413 Evaporation, 27 Exalgin, 430 Excretin, 565 Extension, 14 Extract, Goulard's, 221 pear, 367 pineapple, 367 strawberry, 367 PIECES, 563 ^ Fat in urine, 604, 613 Fats, 513 natural, 368 melting point of, 373 in human body, 376 Feeding experiments, 536 Fehling's solution, 600 Feldspar, 277 Ferment, acetic acid, 528 alcoholic, 337, 527 butylic, 528 curdling, 519 emulsin, 522 fibrin, 526 lactic, 401 nitrifying, 529 organized, 519, 527 pepsin, S59 soluble, or unorganized, 519 urea, 528 Fermentation, alcoholic, 337 butyric, 528 lactic, 528 putrefactive, 529 Ferments in urine, 606 Fermentatives, anti-, 527 Ferric alum, 291 chloride, 289 compounds, 289 hydroxide, 290 with magnesia, 503 nitrate, 291 oxide, 290 phosphate, 292 pyrophosphate, 292 sesquioxide, 290 sulphates, 290 Ferricyanides, 214 670 INDEX. Ferrocyanides, 2 1 3 Ferrous carbonate, 288 chloride, 287 compounds, 287 hydroxide, 288 iodide, 288 lactate, 289 oxalate, 289 oxide, 288 phosphate, 289 protosulphide, 289 saccharated iodide, 288 sulphate, 288 sulphides, 289 tartrate, 291 Fibrin, 479, 485, 597 Fibrinogen, 481 Fibrinoplastin, 481 Filters, silicated carbon, 144 Fire damp, 309 Flavors, arti6cial fruit, 367 pear, 367 pineapple, 367 strawberry, 367 Fluid, Burnett's, 504 soldering, 504 Fluorine, 112 Fluor spar, 1 1 2 Food, absorption of, 542 accessories, 545 approximate principles of, 531 composition of common, 538 cooking of, 541 dynamic energy of, 534 Foods, digestibility of, 540 function of, 543 proteid-sparing, 545 Force, 16 electro-motive, 54 heat, 16 Forces, physical, 1 1 polar, 51 Formulas, empirical, 87 graphic, 87 rational, 87 Fowler's solution, 185 Frauenhofer's lines, 36 Fraxin, 473 Freezing point, 25 Fulminates, -338 Fusel oil, 342 r-ALACTOSE, 355 ^ Galbanum, 321 Galena, or galenite, 217 Gallaceto-phenone, 418 Galvanic cell, theory of, 52 current, 53 Gamboge, 321 Gas, accidental in air, 162 air, 203 coal, 202 composition of, 204 illuminating, 202, 507 marsh, 309 natural, 309 olefiant, 311 water, 203 Gaseous state, 26 Gases, constitution of, 20 difTusion of, 22 poisonous, 501, 507 tension of, 17 Gasoline, 203 Gasometer, 203 Gastric juice, acidity of, 554 action of, 553 analysis of, 552 clinical examination of, 554 Gelatin, 489 Germanium, 215 Germicides, 163 Giant powder, 345 Glass, 215 soluble or water, 215 Glauber's salt, 227 Gliadin, 492 Globin, 482 Globulin, 568, 595 cell, 481 para, 481 plant, 491 serum, 481 Globulins, 478-482 Glucose, 353 detection in urine, 599 estimation of, 601 tests for, 599 Glucoses, 353 Glucosides, 472 Glue, 490 Gluten, 492 fibrin, 492 INDEX. 671 Glycerin, 345 nitro, 346 Glycerins, 344 Glycerinum, 345 Glyceryl trinitrate, 346 Glycocin, 436 Glycogen, 357 Glycol, 344 Glycosuria, 599 Glycyrrhetin, 473 Glycyrrhizin, 473 Gmelin's test, 605 Gold, 252 trichloride, 253 Goulard's extract, 221 Graham's law of diffusion, 23 Gramme, definition, 15 Grape sugar, 353 Graphite, 199 Gravitation, definition of, 11 law of, 1 1 Gravities, specific, table of, 636 Gravity, flask, 13 specific, II Green, Brighton, 248 Brunswick, 248 mineral, 248 mitis, 247 mountain, 248 Neuwieder, 248 Paris, 247 Schweinfurt, 247 verditer, 248 Greenockite, 269 Guaicol benzoyl, 417 carbonate, 417 iodide, 417 salicylate, 417 Guaiacum, 320 Guanidin, 447 Guanin, 447 Guaranine, 461 Gum acacia, 359 Arabic, 359 bassorin, 359 benzoin, 322 British, 356 lac, 320 resins, 321 Senegal, 359 tragacanth, 359 Gums, 319 vegetable, 358 Gun cotton, 358 powder, 237 Gutta percha, 314 Gypsum, 257 U^MATIN,493 '■ ^ hydrochloride, 493 cysto, 494 Hsematite, 285 Hsematoidin, 494 Hsematoporphyrin, 494 Hasmaturia, 598 Hsemin, crystals, 493, 598 Hsemochromagen, 494 Haemocyanin, 494 Haemoglobins, 493 Hsemoglobinuria, 598 Haemoglobinometer, 494 Haines' solution, 600 Halogen elements, 183-298 Haloid derivatives, 330 Hausmanite, 283 Heat, 24 latent, 28 mechanical equivalent, 25 sensible, 30 specific, 29 Heavy spar, 261 Helleborein, 473 Helleborin, 473 Hemaloidin, 495 Hematoxylon, 498 Hemipeptone, 488 Heteroxanthin, 446 Histozym, 519, 526 Homologous series, 304 Hornblende, 262 Hydrates, 85 Hydrazin, 431 acetyl-phenyl, 431 ethyl, 431 hydrate, 431 phenyl, 431 Hydrobilirnbin, 495 Hydrocarbons, 162 benzene, 390 nomenclature of, 308 homologous series of, 308 672 INDEX. Hydrocarbons, nitro-derivatives, 390 radicals, 88 cyanides of, 390 sulphur-derivatives, 390 Hydrogen, 108, 514 alcoholic, 393 ammonium carbonate, 517 and nitrogen, 165 and oxygen, 127 antimoniuretted, 192 arsenide, 182 arseniuretted, 182 basic, 91 bromide, 119 chloride, 115 disodium phosphate, 230 fluoride, 112 nascent, ill oxide, 127 peroxide, 146, 515 phosphoretted, 177 sodium carbonate, 228 phosphate, 230 sulphate, 155 sulphuretted, 152, 507 Hydrometer, 572, 573 Twaddell, 13 Hydro-potassium, carbonate, 238 oxalate, 239 sulphate, 239 tartrate, 239 Hydroquinone, 415 Hydro-sodium sulphate, 227 Hydroxide, 92 Hydroxylamin, 425 Hygroscopic, 75 Hyoscine, 464 hydrobromate, 464 Hyoscyamine, 463 hydrobromate, 463 sulphate, 463 Hypnal, 384 Hyponitrous oxide, 168 Hyposthenisants, 505 Hypothesis, definition of, 9 Hypoxanthin, 446 TCE, 130 A Ichthyol, 389 Illuminating gas, 507 Imids, 422 Imids, benzoyl-sulphonic, 389 Incompatibles, 507 India rubber, 314 Indican, 473, 497, 582 Indigo, 448, 497, 613 carmine, 448 test, 601 Indigotin, 497 Indol, 447 methyl, 448 Induction,. coil, 64 electrical, 46 Inebriants, 505 Inertia, 14 Infusion, 146 Inosite, 355 Invertin, 519, $26 Iodine, 120, 504 compound solution, 121 oxides, 148 Iodoform, 334 lodol, 436 Iridium, 285 Iron, 285, 518 ammonio citrate, 29 1 and ammon. tartrate, 291 and potass, tartrate, 292 and quinine citrate, 292 and strych. citrate, 292 cast, 286 chrome, 279 citrates, 291 oxides, 288 persulphate, 504 phosphates, 289, 292 pig, 286 protosulphate, 288 pyrophosphate, 292 scale compounds of, 291 sulphates, 288 tartrates, 289, 291 wrought, 286 Isologous series, 304 Isomeric bodies, 305 Isomerism, 305 Irritint poisons, 503 TALAP, 320 J Jalapin, 473 Jequirity, 470 Jewelers' rouge, 290 INDEX. 673 KAIRIN. 434 Kalium, 233 Kephir, 352 Keratin, 490 Kermes' mineral, 194 Kerosene, 311 Ketones, 3S5 di- methyl, 386 ethyl-methyl, 385 Kumyss^ 352 T ABARRAQUE'S solution, 231 ^ Labdanum, 320 Lac-dye, 320 Lac sulphuris, 151 Lactalbumin, 568 Lactometer, 13, 571 Lactosazone, phenyl, 351 Lactoscope, 572 Lactose, 351 in milk, 568, 577 in urine, 603 Lamp black, 200 Lana philosophica, 267 Lapis infernalis, 251 Lardacein, 479, 489 Laudanum, 505 Laughing gas, 168 Laurent s polarimeter, 42 Law of Ampere, 20, 80 Avogadro, 20, 80 Berthelet, 99 Charles, 19 definite proportions, 1 10 Graham's, 23 Mariotte, 18 Ohm's, 62 periodic, 105 Leaching, 146 Lead, 217, 504 acetates, 221 binoxide, 219 black, 199 carbonate, 220 chlorids, 218 chromate, 221 dioxide, 219 iodide, 219 nitrate, 220 oxides, 219 Lead peroxide, 219 plaster, 218, 310 protoxide, 219 . -puce oxide, 2ig physiological action, 222 red, 219 sugar of, 221, 362, 504 sulphate, 220 sulphide, 221 white, 220, 362, 504 Lecithin, 346 Legumin, 492 LSpidolite, 224 Leucin, 439, 612 Leucomaines, 471 betain-uric group, 47 1 creatinin group, 472 Levulose, 354 Lieben's test, 603 Light, 31 chemical effects of, 38 color and intensity of, 33 double refraction of, 40 polarization of, 39 transmission of, 32 Lignin, 358 Lime, 255 chloride of, 255 chlorinated, 255 milk of, 256 slaked, 256 stone, 254 superphosphate of, 257 water, 256 Limonite, 285 Liniment, saponis, 317 Ljpaciduria, 604 Lipochrin, 496 Liquid state, 17 Liquor, 146 acidi arsenosi, 185 ammon. acetatis, 243 arsenii et hydrarg. iodidi, 183 calcis, 256 calcis saccharatus, 256 ferri chloridi, 290 nitratis, 146, 291 perchloridi, 290 pernitratis, 291 subsulphatis, 290 tersulpbatis, 290 57 674 INDEX. Liquor, mother, 74 plumbi subacetalis, 146, 221 polasSEB, 235 potass, arsenitis, 185 specific gravity of, 1 6 sodee, 226 sodii arsenatis, 185 chloratse, 231 Liquorice sugar, 473 Liquors, distilled, 339 fermented, 339 malt, 339 Litharge, 219 Lithic acid (uric acid), 443 Lithium, 223 benzoate, 224 bromide, 224 carbonate, 224 citrate, 224 chloride, 223 oxide, 224 salicylate, 224 Litmus, 497 Liter, 15 Liver of sulphur, 238 Lixiviation, 146 Lobelia, 506 Logwood, 498 Lugol's solution, 121 Lunar caustic, 25 1 , 504 Lysol, 412 lUACERATION, 146 '■'^ Madder, artificial, 326 Magnesia, 263 alba, 264 calcined, 263 hydrated, 263 milk of, 263 Magnesite, 264 Magnesium, 262, 516 carbonates, 264 chloride, 263 citrate, 264 hydroxide, 263 oxide, 263 phosphates, 264, 610 sulphate, 263 Magnetic needle, 49 Magnetism, 49, 71 Magnetism, theory of, 51 Magnetite, 285 Magneto-electricity, 67 Magnets, electro, 50 properties of, 49 poles of, 49 Malachite, 244 Malt extract, 521 diastasic value of, 521 Maltin, 520 Maltosazone-phenyl, 353 Maltose, 352 Manganates, 284 Manganese, 283 black oxides, 284 Manganic compounds, 284 Manganite, 283 Manganous carbonate, 283 chloride, 2S3 compounds, 283 hydroxide, 283 oxide, 283 sulphate, 283 sulphide, 283 Manna, 346 dulcite, 347 Mannite, 346 Mannilol, 346 Mannitose, 347 Marble, 258 Mariotte, law of, 18 Marsh gas, 309 Mass, definition of, 10 Massicot, 219 Mastic, 320 Matter, definition of, 9 divisions of, lo radiant, 21 three states of, 16 Maumen^'s test, 375 Measures, table of, 632 Meerschaum, 262 Melanin, 497 Melanogen, 497 Melting point, 25 Menthol, 318 Mercaptan, 387 Mercaptal, 387 Mercaptid, 387 Mercaptol, 387 Mercurial tremors, 275 INDEX. 675 Mercur-amidogen chloride, 270 ammonium chloride, 272 Mercuric chloride, 272 compounds, 272 iodide, 273 nitrate, 274 sulphate, 274 sulphide, 274 Mercurous chloride, 270 compounds, 270 iodide, 271 nitrate, 271 sulphate, 271 Mercury, 269 ammoniated, 272 fulminate of, 391 physiological action, 274 tests, 275 Metabolism, 531 Metaldehyde, 382 Metalloids, 104 Metals, 104 alkali, 223 of the alkaline earths, 253 of group I, 223 group II, 262 group III, 276 group V, 279 group VI, 279 group VII, 283 group VIII, 28s platinum, 294 Metarabin, 360 Meter, 14 Methsemoglobin, 494 Methane, 309, 331 mono-chlor, 331 oxychinolin, 434 trichlor, 331 Methyl acetate, 331 alcohol, 301 amins, 425 bromide, 331, 333 chloride, 331 ether, 302 glycocol, 437 guanidin, 438 iodide, 331 oxide, 361 pyrocatechin, 416 -prophyl-phenol, 318 Metric system, 14 use in prescriptions, 16 Mica, 277 Microzimas, 526 Milli-amp4re, 55 Milliampdremeter, 56 Milk, chemical analyses of, 573 composition of, 566 modified, 569 of lime, 256 of magnesia, 263 standards, 576 sterilized or Pasteurized, 569 sugar (lactose), 568 Mindererus, spirit of, 243 Mineral green, 248 waters, 145 Minium, 219 Mitis green, 247 Mobility, 11 Molasses, 349 Molecular attraction, 14 weights, 80, 82 Molecules, 10, 77 and atoms, multiplication of, 86 composition of, 305 compound, 77, 90 constitution, 305 definition of, 77 elemental, 77 number of atoms in, 81 salt, 92 size and weight of, 21 ternary, 91 Molybdenite, 282 Molybdenum, 282 Molybdic trioxide, 282 Monocalcium phosphate, 257 Monopotassium sulphate, 239 Monosodium phosphate, 230 Monsel's solution, 290 Morphine, 464, 505 Mortar, 256 hydraulic, 256 Motility of stomach, 560 Mountain green, 248 Mucidin, 487 Mucilage, vegetable, 360 * Mucin, 489, 490, 596 Mucus, 490 Murexid, 446 676 Muscarin, 427 Mustard, 502 Mycoderma aceti, 39S, 528 Myohsematin, 494 Myosin, 482 plant, 492 Myosinogen, 482 Myrosin, 522, 519 Myrrh, 321 Mytilotoxin, 469 AJ APHTHA, 324 ^' Naphthaline, 326 Naphthol, 326 Narceine, 458 Narcotics, 505 Narcotine,458 Nascent state. III Natrium, 225 Natural science, definition of, 9 Neurin, 426, 469 Neurotics, 505 Neutrals, 91 Neuwieder green, 248 Niccolite, 292 Nickel, 292 compounds, 293 glance, 292 Nickelous cyanide, 293 hydroxide, 293 sulphate, 293 sulphide, 293 Nicotine, 457 Niobium, 279 Nitrates, 138 Nitre, 236 sweet spirits of, 364 Nitric anhydride, 171 oxide, 169 Nitrils, 422 Nitrils, iso-, 391 Nitrites, 138, 170 Nitro-benzene, 505 Nitro-glycerin, 346 Nitrogen, 159, 297 514 and hydrogen, 165 assimilation of, 511 chloride, 167 dioxide, i6g, 171 INDEX. Nitrogen group, 158 iodide, 168 monoxide, 168 peroxide, 171 protoxide, 168 tetroxide, 171 Nitrous anhydride, 170 fumes, 507 hypo- oxide, 168 oxide, 168, 505 Nomenclature, 93 examples of, 93 irregularities in, 97 of homologous hydrocarbons, 308 rule for, 93 simplified, 95 Non-metallic elements. III, 158 Nuclein, 491 Nutrition, 530 Nux vomica, 506 OCCLUSION, no Ohm, 55 international, 56 Ohm's law, 62 Oidium albicans, 528 Oil, almond, 370 apple, 343 benne, 370 of bergamot, 315 castor, 372 cinnamon, 315 of cloves, 315 cod-liver, 370 of copaiba, 315 cottonseed, 370 croton, 372 of cubebs, 315 elemi, 315 fusel, 342 juniper, 315 lemon, 315 linseed, 371 mineral sperm, 311 neats' foot, 372 olive, 369 r orange peel, 315 palm, 372 peanut, 370 INDEX. 677 Oil, pear, 343 pepper, 315 sesame, or teel, 370 Oils, essential, 315 drying or siccative, 369 fixed, 368 lubricating, 311 non-volatile, 369 sweet principle of, 345 Olefines, 311 Olein, 369 Oleomargarin, 373 Oleoptenes, 315 Oleoresins, 321 Oliver's te6t for biliary acids, 605 Opium, 464, 505 Orcin, 416 Orcinol, 416 Organic bodies containing nitrogen, 422 chemistry, definition of, 296 compounds, synthesis of, 328 radicals, 307 disease- producing, 530 Organic compounds, action of reagents on, 328 constitution of, 301 nomenclature of, 306 qualitative examination of, 297 Organisms in water, 143 Orpiment, 183 Osmium, 295 tetroxide, 295 Osmosis, 73 Ossein, 489 Oxaluria, 609 Oxidation, 124 Oxygen, 122 Oxyhaemoglobins, 493 • Ozocerite, 311 Ozone, 126 PALLADIUM, 294 Palmitin, 369 Pancreatic extracts, 521 diastatic value of, 521 juice, 52s, 560 Papain, S19, 526 Papaverine, 458 Paradox, culinary, 26 Paraffin, 308, 310 meso, 310 neo, 310 normal, 310 Paraxanthin, 446 Paraglobulin, 481, 595 Paraldehyde, 381 Parchment paper, 156, 358 Paregoric, 505 Paris green, 247 Pearlash, 237 Peat, 201 Pectin, 360 Pepsin, 519, 522 Peptone, 596 hemi and anli, 488 tests for, 596 Peptones, 488, 492 in urine, 596 Permanganates, 284 Petroleum distillation, 31 1 Pettenkofer's test, 449 Phenacetin, 432 Phenanthene, 327 Phenates, 410 Phenazone, 432 Phenol, 408, 409 di-hydro, 415 di-methyl, 413 monorbrom, 413 mono-chlor, 413 triatomic, 417 tri-brom, 413 tri-nitro, 414 Phenylamins, 427 Phenyl glucosazone, 354 Phloretin, 473 Phlorizin, 473 Phloroglucin, 417 Phosphates, earthy, 518 Phospho-tungstic acid, 596 Phosphine, 177 Phosphorus, 174, 298, 504 oxides, 179 oxychloride, 178 pentoxide, 179 » physiological action, 176 red, 175 trichloride, 178 Phosphorus trioxide, 178 678 INDEX. Physical forces, 1 1 science, definition of, 9 Physician, duty of, in poisoning, 185 Physics, 9 chemical, 16 Physostigmine, 465 Pialyn, 525 Picnometer, 13 Picrotoxine, 465 Figments, animal, 493 biliary, 495 blood, 496 urinary, 496 Pilocarpine, 465 Piperine, 465 Plaster-of- Paris, 257 lead, 379 Platinum, 294 compounds, 294 metals, 294 sponge, 294 tetrachloride, 295 Plumbago, 199 Plumbates, 220 Plumbic anhydride, 219 Plumboso-plumbic oxide, 219 Flummer's pills, 194 Podophyllin, 320 Poisonous foods, 504 • gases, 501 Poisons and their antidotes, 1 87 corrosive, 499, ^^^2 deliriant, 505 emetic, 504 Poison, rat, 504 Poisons, irritant, 500 neurotic, 500 septic, 500 Polarimeter, Laurent's, 42 Polarity of atoms, 83 of the elements of batteries, 60 Polariscope, 41 Polarization of plates, 60 plane of, 41 rotation of, 41 Poles, 49 Polychroite, 474 Polymerism, 305 Populin, 473 Potash, 235. binoxalate of, 239 Potash, by lime, 235 neutral tartrate, 239 red chromate, 281 red prussiate, 214 yellow prussiate, 210, 213 Potassa, 235 Potassium, 198, 233 acetate, 239 antimonyl tartrate, 240 arsenite, 185 bicarbonate, 238 bichromate, 503 bromide, 234 carbonate, 237, 238 chlorate, 236 chloride, 234, 516 chromate, 281 chrome alum, 279 cyanide, 234, 505 dichromate, 281 ferricyanide, 214 ferrocyanide, 213, 268 fluoride, 234 haloid salts of, 233 hydrate, or hydroxide, 235 hypochlorite, 236 iodide, 198, 234 manganate, 284 mercuric iod., 593 nitrate, 236 oxalates, 239 oxide, 235 pentasulphide, 238 perchlorate, 236 permanganate, 284 plumbate, 220 quadroxalate, 239 sulphates, 238 sulphides, 238 sulphites, 239 tartrates, 239 Potato spirit, 342 Potential, 47 Powder, of algaroth, 193 putty, 217 Power, electrical horse, 56 rotatory, 43 the specific, 43 Pressure, standard of, 19 Prism, Nicol, 40 Propeptones, 595 INDEX. 679 . Propylatnin, 426 Protagon, 346 Proteids, 470, 475, 513 classificatioq of, 478 coagulated, 479 poisonous, 470 Prussian blue, 214 Prussic acid, 210 Pseudomorpliine, 459 Ptomaines, 466 in urine, 606 physiological action, 467 Ptyalin, 519, 525 Purple of Cassius, 253 Pus in urine, 598 Pyalin, 561 Putrescin, 469 Pyrethrum, 320 Pyridin, 435 Pyrocatechin, 416 Pyrogallin, 418 ; Pyrogallol, 418 Pyrogallopyrin, 435 Pyrolusite, 283 Pyromorphite, 217 Pyroxylin, 251, 358 Pyrrol, 435 QUARTZ, 214 Quercitannic acid, 475 Quercitrin, 474 Quieting cordials, 505 Quinicine, 462 Quinidine, 462 Quinine, 461 acid sulphate, 462 bisulphate, 462 hydrobromate, 462 hydrochlorate, 462 sulphates, 462 valerianate, 462 RADICALS, 88 compound, 88 organic, 307 Radiometer, 21 Ranke's experiments, 533 Ray, ordinary and extraordinary, 40 Reactions, 98 rules for writing, 100 synthetical, 328 Reagent, definition of, 98 Dragendorff's, 452 Fr5hde's,452 Marm^'s, 452 Mayer's, 45 1 Sonnenschein's, 45 1 Wagner's, 452 Reagents, action of, 328 Realgar, 184 Red crocus, 290 Reduction, no Reinsch's test, 188 Rend-rock, 345 Rennet, 525 Rennin, 525 Resin soap, 321 Resins, 315, 319, 321 fossil, 321 gum, 3 '9. 321 oleo, 319, 321 separation of, 320 Resopyrin, 433 Resorcin, 415 ptyalin, 416 physiological action of, 416 Resorcinol, 415 Rboeadine, 450 Rheophores, 63 Rhigolene, 311 Rhodium, 285 Rhodochrosite, 283 Rhombohedra, 230 Roberts' test, 593 Rochelle salt, 240 Rotation, specific, 348 Rouge, jeweller's, 290 Rosin, 321 Rottlerin, 320 Rubidium, 240 Ruby, 277 Rum, 340 Rust, 287 .Ruthenium, 285 CACCHARATES, 351 '-' Saccharimeters, 41 Saccharine, 389 68o INDEX. Saccharomycetes albicans, 528 Saccharoses, 348 Saccharum lactis, 351 Saffron, 498 Sal ammoniac, 241 volatile, 242 Saleratus, 238 Salicin, 474 Salicylates, 366 phenyl, 366 Saliva, composition of, 550 uses of, 551 Salol, 366, 560 Salophen, 367 Salt, common, 225, 502 Epsom, 263 Glauber's, 227 of lemon, 239 of Saturn, 221 of sorrel, 239 of tartar, 237 Rochelle, 406 Saltpetre, 236 Chili, 230 Salts, 92 acid, 92, 179 basic or sub-, 93 double, 92, 179 ferric, 97 ferrous, 97 metallic, 504, 516 normal, 92, 179 copper, 504 Santonin, 474 Santoninum, 474 Saponification, 344, 363 Saponin, 474 Sapphire, 277 Sarcosin, 437 Saturated solution, 72 Scale compounds of iron, 291 Scales, thermometric, 30 Scheele's green, 185, 247 Schulite, 282 Schweinfurth green, 247 Science, definition of, 9 natural, g physical, 9 Scoparius, 460 Selenium, 158 Series, 311 Serolin, 565 Serpentine, 262 Serpents, Pharaoh's, 213 Shell-lac, 320 Siderite, 285 Silica, 518 Silicates, 215 Silicic anhydride, 215 hydride, 214 oxide, 215 Silicium, 214 Silicon, amorphous, 214 crystalUzed, 214 graphitic, 214 Silver, 249 bromide, 250 chloride, 250 cyanide, 251 fulminate, 338 iodide, 250 nitrate, 250, 504 oxides, 250 salts in photography, 251 Skatol, 448 Slag, 286 Smaltite, 293 Smithsonite, 265 Soaps, 378 green, 379 lead, 379 resin, 320 sapo mollis, 379 viridis, 379 soft, 379 white Castile, or Sapo, 379 Soapstone, 262 Soda, 226 ash, 228 process, 228 blackball, 228 caustic, 226 lye, 226 sal, 228 washing, 228 water, 206 Sodii, arsenas, 23 1 sulphocarbolas, 421 Sodium, 198, 225 benzoate, 231 bicarbonate, 229 bisulphate, 227 INDEX. 68i Sodium bisulphite, 227 borates, 230 bromide, 225 carbonate, 228 chlorate, 231 chloride, 225, 516 cresotate, 412 hydrate, 226 hydroxide, 226 hypobromite, 148 Hypochlorite, 231 hyposulphite, 227 iodide, 226 sulphate, 227 nitrate, 230 oxides, 226 phosphates, 230 potassium tartrate, 240 pyroborate, 230 P3rrophospfaate, 230 salts, physiological action of, 232 sulphates, 226 sulphite, 227 tetraborate, 230 thiosulphate, 227 tUDgstate, 282, 593 Solanine, 474 Solid state, 1 7 Solution, 71, 72 Fehling's, 247 Lugol's, 121 Monsels, 290 of gases, 7 1 Solveol, 412 Soninal, 365 Soot, 200 Sorbin, 355 Sorbinose, 355 Sorbite, 347 Sorbitol, 347 Sozoiodol, 421 Spar, heavy, 261 Sparteine, 460 Specific gravity, 1 1 Spectra, absorption, 37 Spectroscope, 34 Spectrum, 33 analysis, 36 continuous, 35 solar, 36 Spelter, 265 58 Sphalerite, 265 Spirit of Mindererus, 243 methylated, 337 wood, 336 Spirits, 317 of nitre, 364 Sprue, 528 Staunum, 215 Starch, 356 paste, 356 Steapsin, 525 Stearin, 369 Stearopienes, 315 Steel, 286 Bessemer, 287 Stercobilin, 495 Stercorin, 565 Siibine, 192 Stings, 507 Stochiometry, loi Stolzite, 282 Stomach pump, 501 Stone, blue, 246 Storax, 322 Stout, 340 Stramonium, 506 Slrontianite, 260 Strontium, 260 bromide, 260 iodide, 260 lactate, 260 nitrate, 260 Strophanthin, 474 Strychnine, 465, 506 Sublimate, corrosive, 272, 504 Sublimation, 28 Substitution products, 327 Succus entericus, 562 Sucrates, 351 Sugar, barley, 349 cane, 348 grape, 353 in urine, 599 invert, 349 liquorice, 473 malt, 352 milk, 351,568 of lead, 221 Sugars, 348 Suine, 373 Sulphates in urine, 517,588 682 INDEX. Sulphates, tests for, 157 Sulphocarbolate, 232 Sulphocarbonates, 210 Sulphocyanates, 213 Sulphonal, 388 Sulphonate, beta-naphthol, 389 Sulphur, 149-298 flowers of 1 50 liver of, 238 roll, 150 " Sulphuretted hydrogen, 151 Sulphuric ether, 362 Sulphurous bromide, 1 53 chloride, 153 iodide, 153 oxide, 154, 162, 507 Superphosphate of lime, 257 Sylvite, 234 Synaptase, 522 Syncopants, 505 .Synthesis, animal, 513 of organic compounds, 328 Syntonin, 482, 483 Syrup ipecacuanhEe, 502 soothing, 505 specific gravity of, 1 6, 637 TABLE of behavior of soluble pro- teids, 477 of chemical elements, 78 of compound radicals, 89, 307 of diet, S3 1 of digestive juices and their fer- ments, 550 of electro-chemical series, 84 of hydrocarbon radicals, 307 of identification of principal fixed oils, 377 of solubility of chemicals, 637,638 of specific gravities, 636 of wave lengths, 33 of weights and measures, 632 Talc, 262 Tallow, 373 Tannin, 474 Tanret's test, 593 Tantalum, 279 Tartar, cream of, 239, 406 crude, 239 Tartar, emetic, 240, 406, 503 soluble, 239 Taurin, 437, 449 Tellurium, 158 Temperature, critical, 124, 206 - definition of, 29 standard, 20 Terebene, or terpin, 313 Terra alba, 257 Test, Bethendorf's, 190 elaidin, 376 Ewald's salol, 560 Fleitmann's, 189 Gmelin's, 605 Gutzeit's, 190 Marsh's, 188 Pettenkofer's, 449 Reinsch's, 188 Tetanin, 469 Tetramethylammonium, 426 Tetramethyldiamin, Thebaine, 459 Theine, 461 Theobromine, 465 Theory, definition of, 9 Thermal unit, 29, 535 Thermometers, 30 Thrush, 528 Thymol, 318, 413 Tin, 215 chloride, 504 compounds of, 216 foil, 216 sheet, 216 stone, 215 Tincal, 230 Tinctures, 338 Tinctures, sp. gr. of, 16 Tolu, 322 Toluene, 325 dihydroxy, 416 Torula, 527 Toxicological analysis, 185 Toxines, 470 Treacle, 349 Tricalcium phosphate, 257 Tricupric carbonate, 247 Trimethyl-oxethyl-aramonium, 426 Tri-methyl-vinyl ammonium, 426 Triple-phosphate, 610 Trommer's test, 599 INDEX. 683 Tropseolin, 554 Trypsin, 519, 525, 561 Tuberculin, 471 Tuberculocidin, 471 Tungstates, 282 Tungsten, 282 Turmeric, 497 TurnbuU's blue, 214 Turpentine, 313 Turpeth mineral, 274 Types, ammonia, 422 water, 422 Typhotoxin, 469 Tyrein, 484 Tyrosin, 612 Tyrotoxicon, 469 TTRANIUM, 279 *-' Urates, 607 Urea, 441 estimation of, 442, 58S origin of, 442 Urethane, 365 tesu, 365 Urinary deposits, 607 pigments, 496 tests, 441 Urine, 579 analysis of, 579 black, 497 chlorides in, 585 color, 581 composition, 581, 624 general properties, 580 odor, 585 phosphates in, 587 quantity, 581 reaction, 580 speciGc gravity, 583 total solids, 584 Ultzmann's test, 605 Urinometer, 13 Urobilin, 496, 582 Urochrome, 496 Uroerythrin, 496 Urohsematin, 494 Uromelanin-, 496 Urostealite, 623 Uroxanthin, 496 V 'ANADIUM, 279 Vanillin, 382 Vapor, watery, in air, 161 Veratrine, 466 Verdigris, 247 Vermilion, 274 Vinegar, 395 Vitellin, 480, 491 Vitriol, blue, 246 green, 288, 504 white, 267 Volt, 54 international, 56 Vulcanite, 314 WASTE, elimination of, 531 VV Water, 127, 514 alkaline, 145 analysis, 134 chalybeate, 145 character of good drinking, 134 glass, 215 hardness of, 136 ice, 133 laurel, 505 lime, 255 mineral, 145 natural, 132 of constitution, 264 of crystallization, 73 potable, 132 purification of, 144 rain, 132 saline, 145 snow, 132 soda, 206 spring, 133 sulphuretted, 145 surface, 134 thermal, 146 vapor of, 161 well, 133 Waters, acid, I46 biological examination, 143 carbonated, 145 deficiency of, SIS detection of impure, 577 medicated, 317 Watt, 5S Wax, mineral, 311 684 INDEX. Weight, atomic, 83 molecular, 82 Weights and measures, table of, 632 Werner-Schmid process, 573 Whiskey, 340 White lead, 221 permanent, 221 precipitate, 272 vitriol, 267 Wine, 341 Wines, composition of, 340 Witherite, 261 Wolfram, 282 Wolframite, 282 Wood spirit, 336 Wounds, 507 Wulfenite, 217 XANTHIN, 446, 623 Xanthophyll, 498 Xenols, 413 Xylenols, 413 Xyloidin, 356 ^EAST, 527 Yellow wash, 272 7ERO, 19 ^ Zinc, 265 amalgamation of, 60 butter of, 266 chloride, 266, 504 hydroxide, 267 oxide, 266 sulphate, 267 sulphocarbolate, 232 tests, 268 toxicology, 268 white, 221 Zinci acetas, 267 bromidum, 266 carbonas precipitatus, 267 flores, 266 iodidum, 266 phosphidum, 266 valerianas, 267 Zincum, 266 Zymogen, 520 CATALOGUE No. 7. MARCH, 1804. BOOKS FOR STUDENTS, INCLUDING THE ? QUIZ-COMPENDS ? New Series of Manuals^ Anatomy, , CONTENTS. FAGB Chemistry^ . Children's Diseases, pentistry. Dictionaries, £ve Diseases, Electricity; . Gynecology, Hygiene, Materia Medica, Medical Jurisprudence, Nervous Diseases, . . 6 PAGE Obstetrics. . , , .10 Pathology, Histology, , . 11 Pharmacy, . . ... 12 Physical Diagnosis, . .11 Physiology, , Practice of Medicine, Prescription Books, ? (^uiz-Compends ? Sl«ih Diseases, . . .12 Surgery and Bandaging, . 13 Therapeutics, . , , g Urine and Urinary Orgaijs, 13 Venereal Diseases, . .13 . II IX, 12 14, 15 PUBLISHED BY P. BLAKISTON, SON & CO., Medical Booksellers, Importers and Publishers. LARGE STOCK OF ALL STUDENTS" BOOKS, AT THE LOWEST PRICES. 1012 Walnut Street, Philadelphia. *0* For sale by all Booksellers, or any book will be sent by mail, postpaid, upon receipt of price. Catalogues of books on all branches (tf Medicine, Dentistry, Pharmacy, etc., supplied upon application. GOULD'S } c r. ^ DICTIONARY / See Page 16. "An excellent Series of Manuah." -^Arektves of Gynmcelo£iy. A NEW SERIES OF STUDENTS' MANUALS On the various Branches of Medicine and Surgery. Can be used by Students of any College. Price ot each. Handsome Cloth, $3.00. Full Leather, $3.60 The object of this series is to furnish good manuals for the medical student, that will strike the medium between the compend on one hand and the prolix text- book on the other — to contain all that is necessary for the student, without embarrassing him with a flood of theory and involved statements. They have been pre- pared by well-known men, who have had large experience as teachers and writers, and who are, therefore, well informed as to the needs of the student. Their mechanical execution is of the best — good type and paper, handsomely illustrated whenever illustrations are of use, and strongly bound in uniform style. Each book is sold separately at a remarkably low price, and the immediate success of several of the volumes shows that the series has met with popular favor. No. 1. SURGERY. 318 Illustrations. Third Edition. A Manual of the Practice of Surgery. By Wm. J. Walsham, M.D., Asst. Surg, to, and Demonstrator of Surg, in, St. Bartholomew's Hospital, London, etc. 318 Illustrations. Presents the introductory facts in Surgery in clear, precise language, and contains all the latest advances in Pathology, Antiseptics, etc. " It aims to occupy a position midway between the pretentious manual and the cumbersome System of Surgery, and its general character may be summed up in one word — practical." — The Medu eal Bulletin. " Walsham, besides being an excellent surgeon, is a teacher in its best sense, and having had very great experience' in the preparation of candidates Tor examination, and their subsequent professional career, may be relied upon to have carried out his work successfully. Without following out in detail his arrange- ment, which is excellent, we can at once say that his book is an embodiment of modem ideas neatly strung together, with an amount ot careful organizsation well suited to the candidate, and, indeed, lo the practitioner." — Britiek Medical Journal, Price ot each Book, Cloth, $3.00; Leather, $3.60. THE NEW SERIES OF MANUALS. No. 2. DISEASES OF A^OMEN. 160 Hlus. NEW EDITION. The Diseases of Women. Including Diseases of the Bladder and Urethra. By Dr. F. Winckel, Professor of Gynaecology and Director of the Royal University Clinic for Women, in Munich. Second Edition. Re- vised and Edited by Theophilus Parvin, M.D., Professor of Obstetrics and Diseases of Women and Children in Jefferson Medical College. 150 Engrav- ings, most of which are original. " The book will be a valuable one to physicians, and a safe and satSsfactoiy one to put into the hands of students. It is issued in a neat and attractive form, and at a very reasonable price." — Boston Mtdical and Surgical Journal . No. 3. ANATOMY. Sixth Edition. 311 ILLUSTRATIONS. Holden's Anatomy. A Manual of the Dissections of the Human Body. By John Langton, f. r. c. s., Sur- geon to, and Lecturer on Anatomy at, St. Bartholo- mew's Hospital. Carefully Revised by A. Hewson, M.D., Demonstrator of Anatomy, Jefferson Medical College; Chief of .Surgical Clinic, Jefferson Hospital; Mem. Assoc. Amer. Anatomists, etc. 31 1 Illustrations. This book comes bound in oil- cloth — price ;jS3.oo — as well as in the regular cloth and leather styles. *• The work before us is a brilliant example of the new order of text-books. * * * We would call special attention to the character of the illustrations with which the volume is bountifiilly furnished " — American Jtmrnal of Medical Sciences. No. 4. PHYSIOIiOG-Y. Sixth Edition. 354 ILLUSTRATIONS AND A GLOSSARY. A Manual of Physiology. By Gerald F. Yeo, m.d., F.R.C.S., Professor of Physiology in King's College, London. 254 Illustrations and a Glossary of Terms. Sixth American from last English Edition, revised and improved. This volume was specially prepared to furnish students with a new text-book of Physiology, elementary so far as to avoid theories which have not borne the test of time and such details of methodi as are unnecessary for students in our medical colleges. "The brief examination I have given it was so favorable that I placed it in the list of text-books recommended in the circular of the University Medical College." — Prof. Lewis A. Stzmson, m.d., 57 East 33d Street t New York. Price of each Book, Cloth, $3.00; Leather, $3.60. THE NEW SERIES OF MANUALS. No. 6. DISEASES OP CHILDREN. SECOND EDITION. A Manual. By J. F. Goodhart, m.d., Phys. to the Evelina Hospital for Children; Asst. Phys. to Guy's Hospital, London. Second American Edition. Edited and Rearranged by Louis Starr, m.d., Clinical Prof, of Dis. of Children in the Hospital of the Univ. of Pennsylvania, and Physician to the Children's Hos- pital, Phila. Containing many new Prescriptions, a list of over 50 Formulae, conforming to the U. S. Pharma- copoeia, and Directions for making Artificial Human Milk, for the Artificial Digestion of Milk, etc. Illns. " The author has avoided the not uncommon error of writing a book on general medicine and labeling it ' Diseases of Children,' but has steadily kept in view the diseases which seemed to be incidental to childhood, or such points in disease as appear to be so peculiar to or pronounced in children as to justify insistence upon them. * * * A safe and reliable guide, and in many ways admirably adapted to the wsftits of the student and practitioner." — American Journal of Medical Science. No. 6. MATERIA MEDIOA, PHARMACY, PHARMACOLOGY, AND THE- RAPEUTICS. A Handbook for Students. By Wm. Hale White, M.D., F.R.C.P., etc.. Physician to, and Lecturer on Ma- teria Medica, Guy's Hospital; Examiner in Materia Medica, Royal College of Physicians, London, etc. American Edition. Revised by Reynold W. Wilcox, M.A., M.D., Prof, of Clinical Medicine at the New York Fost-Graduate Medical School and Hospital ; Assistant Visiting Physician Bellevue Hospital. 5^° pages. In preparing this book, the wantsof the medical student of to-day have been constantly kept in view. The division into several sub- jects, which are all arranged in a systematic, practical manner, will be found of great help in mastering the whole. The work of the editor has been mainly in the line of adapting the book to the use of American students ; at the same time, however, he has added much new material. Dr. Wilcox's long experience in teaching and writing on therapeutical subjects particularly iits him for the position of editor, and the double authorship has resulted in mak- ing a very complete handbook, containing much minor useful in- formation that if prepared by one man might have been overlooked. Price ol each Book, Cloth, $3.00 ; Leather, $3.50. THE NEW SERIES OF MANUALS. No. 7. MEDICAL JURISPRUDBNCB AND TOXICOLOGY. THIRD REVISED EDITION.^ By John J. Reese, m.d.. Professor of Medical Jurispru- dence and Toxicology in the University of Pennsyl- vania ; President of the Medical Jurisprudence Society of Phila.; Third Edition, Revised and Enlarged. " Tliis admirable text-book." — Amer.Jour. of Med. Sciences. " We lay this volume aside, after a careful perusal of its pages, with the profound impression that it should be in the hands of every doctor and lawyer. It fiiUy meets the wants of all students He has succeeded in admirably condensing into a handy volume all the essential points." — Gncinnati Lancet and Clinic. No. a DISEASES OF THE BYE. iVeBlus. FOURTH EDITION. Diseases of the Eye and their Treatment, A Handbook for Physicians and Students. By Henry R. Swanzy, A.M., M.B., F.R.C.S.I., Surgeon to the National Eye and Ear Infirmary; Ophthalmic Surgeon to the Adelaide Hospital, Dublin; Examiner in Ophthalmic Surgery in the Royal University of Ireland, Fourth Edition, Thoroi^hly Revised. 176 Illustrations and a Zephyr Test Plate. 500 pages. ** Mr. Swanzy has succeeded in producing the most intellectually conceived and thoroughly executed Tesume of the science within the limits he has assigned himself. As a 'students' handbook/ small in size and moderate in price, it can hardly be equaled." — Medical News. *' A full, clea,r, and comprehensive statement of Eye Diseases and their treatment, practical and thorough, and we feel folly jus^ tified in commending it to our readers. It is written in a clear apd forcible style, presenting in a condensed yet comprehensive fotm current and modem information that will prove alike beneficial to the student and general practitioner." — Southern Practitioner. No. 9. MENTAL DISEASES. WITH ILLUSTRATIONS. JUST READY. Lectures on Mental Diseases, designed for Medical Stu- dents and General Practitioners. By Henry Putnam Stearns, a.m., m.d., Physician Superintendent at the Hartford Retreat, Lecturer on Mental Diseases in Yale University, New Haven, Conn., Hon. Mem. British Psycho. Asso'n, etc. With Illustrations and a Digest of the Laws of the various Stafes relating to the Commit- ment and Care of the Insane. 636 pages. Price of each Book, Cloth, $3.00 ; Leather, $3.60. 6 STUDENTS* TEXT-BOOKS AND MANUALS. ANATOMY. Morris' New Text-Book on Anatomy. Now Ready. By ten leading Surgeons and Anatomists, and Edited by Henry Morris, f.r.'C.s. 791 Specially Engraved Illustrations, 214 ot which are printed in colors. Octavo. 1280 pages. Price in Cloth, 7.50 ; Sheep, 8,50 ; Half Russia, giso *#* Send for Descriptive Circular and Sample Pages. Macalister's Human Anatomy. 816 Illustrations. A new Text-book for Students and Practitioners, Systematic and Topo- graphical, including the Embryology, Histology, and Morphology of Mao. With special reference to the requirements of Practical Surgery and Medicine. With 816 Illustrations, 400 of which are original. Octavo. Cloth, 7.50; Leather, 8.50 Ballou's Veterinary Anatomy and Physiology. Illustrated. By Wm. R. Ballou, m.d.. Professor of Equine Anatomy at New York College of Veterinary Surgeons. 29 graphic Illustrations, lamo. Cloth, 1.00; Interleaved for notes, 1.25 Holden's Dissector. A manual of Dissection of the Human Body. Sixth Edition. Edited by A. Hewson, m.d.. Demonstra- tor of Anatomy at Jefferson Medical College. 311 Illustrations, many of which are new. Oil-cloth, 3.00; Sheep, 3.50 Holden's Human Osteology. Comprising a Description of the Bones, with Colored Delineations of the Attachments of the Muscles. The General and Microscopical Structure of Bone and its Development. With Lithographic Plates and Numerous Illus- trations. Seventh Edition. 8vo. Cloth, 6,00 Holden's Landmarks, Medical and Sui^cal. 4th Ed. Clo,,i.25 Potter's Compend of Anatomy. Fifth Edition. Enlarged. x6 Lithographic Plates. 117 Illustrations. Seepage 14. Cloth, i.oo; Interleaved for Notes, 1.25 CHEMISTRY. Bartley's Medical Chemistry. Third Edition. A text-book prepared specially for Medical, Pharmaceutical, and Dental Stu- dents. With 50 Illustrations, Plate of Absorption Spectra, and Glossary of Chemical Terms. Revised and Enlarged. Cloth, Trimble. Practical and Analytical Chemistry. A Course in Chemical Analysis, by Henry Trimble, Prof, of Analytical Chem- istry in the Phila. College of Pharmacy. Illustrated. Fourth Edition, Enlarged. Svo. Cloth, 1.50 Bloxam's Chemistry, InorgSnic and Organic, with Experiments. Seventh Edition. 281 Illustrations. Cloth, 4.50 ; Leather, s.50 48- See faget 2 to sfor list of Studentt' Manuals . STUDENTS' TEXT-BOOKS AND MANUALS. 7 Chemistry : — Continued. Richter's Inorgranic Chemistry. Fourth American, from Sixth German Edition. Translated by Prof. Edgar F. Smith, ph.d. 89 Wood Engravings and Colored Plate of Spectra. Cloth, a.oo Richter's Organic Chemistry, or Chemistry of the Carbon Compounds. Illustrated. Second Edition. Cloth, 4.50 Syroonds. Manual of Chemistry, for the special use of Medi- cal Students. By Brandrbth Sthonds, a.m., m.d., Asst. Physician Roosevelt Hospital, Out-patient Department ; Attend- ing Physician Northwestern Dispensary, New York. Cloth, 2.00 LefTmann's Compend of Medical Chemistry. Including Urinary Analysis. Third Edition. Revised. See page IS- Cloth, i.oo; Interleaved for Notes, 1.25 Muter. Practical and Analytical Chemistry. Fourth Edi- tion. Revised, to meet the requirements of American Medical Colleges, by Prof. C. C. Hamilton. Illustrated. Cloth, 1.25 Holland. The Urine, Common Poisons, and Milk Analysis, Chemical and Microscopical. For Laboratory Use. Fourth Edition, Enlarged. Illustrated. Cloth, i.oo Woody. Essentials of Chemistry for the Medical Student. Third Edition. Cloth, 1.25 CHILDREN. Goodhart and Starr. The Diseases of Children. Second Edition. By J. F. Goodhart, m.d.. Physician to the Evelina Hospital for Children; Assistant Physician to Guy's Hospital, London. Revised' and Edited by Louis Starr, m.d.. Clinical Professor-of Diseases of Children in the Hospital of the Univer- sity of Pennsylvania; Physician to the Children's Hospital, Philadelphia. Containing many Prescriptions and Formulae, conforming to the U. S. Pharmacopoeia, Directions for making Artificial Human Milk, for the Artificial Digestion of Milk, etc. Illustrated. Cloth, 3.00; Leather, 3.50 Hatfield. Diseases of Children. By M. P. Hatfield, m d.. Professor of Diseases of Children, Chicago Medical College. Colored Plate. i2mo. Cloth, i.oo; Interleaved, 1.25 Starr. Diseases of the Digestive Organs in Infancy and Childhood. With chapters on the Investigation of Disease, and on the General Management of Children. By Louis Starr, H.D., Clinical Professor of Diseases of Children in the Univer- sity of Pennsylvania. Illus. Second Edition. Cloth, 2,25 J^ See pages 14 and IS for list o/fQuiz-f^tnpendsf 8 STUDENTS' TEXT-BOOKS AND MANUALS. DENTISTRY. Fillebrowil. Operative Dentistry. 330IUUS. Cloth, 2.50 Flagg's Plastics and Plastic Fillingf. 4t^ Ed. Cloth, 4.00 Gorgas. Dental Medicine. Fourth Edition. Cloth, 3.90 Harris. Principles and Practice of Dentistry. Including Anatomy, Physiology, Pathology, Therapeutics, Dental Surgery and Mechanism. Twelfth Edition. Revised and enlarged by Professor Gorgas. 1028 Illustrations. Cloth, 7,00 ; LeaUier, 8.00 Richardson's Mechanical Dentistry. Sixth Edition. By Warren. 600 Illustrations. 8vo. Cloth, 4.50; Leather, 5.50 Sewill. Dental Surgery. 200 Illustrations. 3d Ed. Clo.,3.00 Taft's Operative Dentistry. Dental Students and Practitioners. Fourth Edition. 100 Illustrations. Cloth, 4.25 ; Leather, 5.00 Talbot. Irregularities of the Teeth, and their Treatment. Illustrated. 8vo. Second Edition. Cloth, 3.00 Tohies' Dental Anatomy. Third Ed. 191 lUus. Cloth, 4.00 Tomes* Dental Surgery. 3d Edition. 292 Illus. Cloth, 5.00 Warren. Compend of Dental Pathology and Dental Medi- cine. Illustrated. 2d Ed. Cloth, i. 00; Interleaved, 1,25 DICTIONARIES. Gould's New Medical Dictionary. Containing the Definition and Pronunciation of all words in Medicine, with many useful Tables, etc, % Dark Leather, 3.25 ; % Mor., Thumb Index, 4.25 Gould's Pocket Dictionary. 12,000 Medical Words Pro- nounced and Detined, Containing many Tables and' an Elaborate Dose List. Thin 64mo. Leather, gilt edges, 1.00; with Thumb Index, 1.25 Harris* Dictionary of Dentistry. Fifth Edition. Completely revised by Prof. Gorgas. Cloth, 5.00; Leather, 6.00 Cleaveland's Pronouncing Pocket Medical Lexicon. Small pocket size. Cloth, red edges .75 ; pocket-book style, i.oo Longley *s Pocket Dictionary. The Student's Medical Lexicon, giving Definition and Pronunciation , with an Appendix giving Abbreviations used in Prescriptions, Metric Scale of Doses, etc. 24mo. Cloth, I.oo; pocket-book style, x.35 EYE. Hartridge on Refraction. 5th Edition. Illus. Cloth, 2.00 Swanzy. Diseases of the Eye and their Treatment. 176 Illustrations. Fourth Edition. Cloth, 3 00; Leather, 3.50 Fox and Gould. Compend of Diseases of the Eye and Refraction, 2d Ed. Enlarged. 71 Illus. 39 Formulae, Cloth, I.oo; Interleaved for Notes, x.25 9^- See pages 2 to s /or list of Students' Manuals. STUDENTS' TEXT-BOOKS AND MANUALS. 9 ELECTRICITY. Bigelow. Plain Talks on Medical Electricity. Cloth, x.oo Mason's Compend of Medical Electricity. Cloth, x.oo Steavenson and Jones. Medical Electricity. A Practical Handbook. Just Ready. Illustrated. i2mo. Cloth, 3.50 HYGIENE. Coplin and Bevan. Practical Hygiene. By W. M. L, Cop- lin. Adjunct Professor of Hygiene, Jefferson Medical College, Philadelphia, and Dr. D. Bevan. Illustrated. Cloth, 4.00 Parkes' (£d. A.) Practical Hygiene. Seventh Edition, en- larged. Illustrated. 8vo. Cloth, 4.50 Parkes' (L. C.) Manual of Hygiene and Public Health. Second Edition. i2nio. Cloth, 2.50 Wilson's Handbook of Hygiene and Sanitary Science. Seventh Edition. Revised and Illustrated. Cloth, 3.25 MATERIA MEDICA AND THERAPEUTICS. Potter's Compend of Materia Medica, Therapeutics, and Prescription Writing. Fifth Edition, revised and improved. Seepage!^. Cloth, 1.00; Interleaved for Notes, 1.25 Davis. Essentials of Materia Medica and Prescription Writing. By J, Aubrey Davis, m.d., Demonstrator of Obstet- rics and Quiz-Master on Materia Medica, University of Penn- sylvania. i2mo. Interleaved. Net, 1.50 Biddle's Materia Medica. Twelfth Edition. By the late John B. Biddle, m.d. Revised by Clement Biddle, m.d. 8vo. Illustrated. Cloth, 4.25; Leather, 5.00 Potter. Handbook of Materia Medica, Pharmacy, and Therapeutics. Including Action of Medicines, Special Thera- peutics, Pharmacology, etc. By Saml. O. L. Potter, m.d., M.R.c.p. (Lond.), Professor of the Practice of Medicine in Cooper Medical College, San Francisco. Fourth Revised and Enlarged Edition. 776 pages. 8vo. Qoth, 4.00; Leather, 5.00 W^hite and Wilcox. Materia Medica, Pharmacy, Phar- macology, and Therapeutics. A Handbook for Students. By Wm. Hale White, m.d,, f.r.c.p., etc.. Physician to and Lecturer on Materia Medica, Gny's Hospital. Revised by Reynold W. Wilcox, m.d.. Professor of Clinical Medicine at the New York Post Graduate Medical School, Assistant Physician Bellevue Hospital, etc. American Edition. Clo.,3.00; Lea., 3.50 9^- See pages 14 and ij for list of f Quix- Compends f 10 STUDENTS' TEXT-BOOKS AND MANUALS. MEDICAL JURISPRUDENCE. Reese. A Text-book of Medical Jurisprudence and Toxi- cology. By John J. Reese, m.d., Frofessor of Medical Juris- prudence and Toxicology in the Medical Department of the University of Pennsylvania ; Physician to St. Joseph's Hospital. Third Edition. Cloth, 3.00; Leather, 3.50 NERVOUS DISEASES. Gowers. Manual of Diseases of the Nervous System. A Complete Text- book. By William R. Gowers, m-d.. Prof. Clinical Medicine, University College, London. Physician to National Hospital for the Paralyzed and Epileptic. Second Edition. Revised, Enlarged, and in many parts Rewritten. With many new Illustrations. Octavo. Vol. I. Diseases of the Nerves and Spinal Cord. 616 pages. Cloth, 3.50 Vol. II. Diseases of the Brain and Cranial Nerves. General and Functional Diseases. Cloth, 4.50 Ormerod. Diseases of Nervous System, Student's Guide to. By J, A. Ormerod, m.d., Oxon,, f.r.c.p. (London), Member Path- ological, Clinical, Ophthalmological, and Neurological Societies, Physician to National Hospital for Paralyzed and Epileptic and to City of London Hospital for Diseases of the Chest, Demon- strator of Morbid Anatomy, St. Bartholomew's Hospital, etc. With 75 Wood Engravings. Cloth, 2.00 OBSTETRICS AND GYN-ffiCOLOGY. Davis. A Manual of Obstetrics. By Edw. P. Davis, Clinical Lecturer on Obstetrics, Jefferson Medical College, Philadelphia, 16 Plates, and 130 Illustrations. i2mo. 2d Edition. Cloth, Byford. Diseases of Women. The Practice of Medicine and Surgery, as aj^lied to the Diseases and Accidents Incident to Women. By W. H. Byford,A.M.,M.D., Professor of Gynaecology in Rush Medical College and of Obstetrics in the Woman's Med- ical College, etc., and Henry T. Byford, m.d., Surgeon to the Woman's Hospital of Chicago. Fourth Edition. Revised and Enlarged. 306 Illustrations, over zoo of which are original. Octavo. 832 pages. Cloth, 2.00 ; Leather, 2.50 Lewers* Diseases of Women. A Practical Text-book. 139 Illustrations. Second Edition. Cloth, 2.50 Parvin*s Winckel*s Diseases of Women. Second Edition. Including a Section on Diseases of the Bladder and Urethra. 150 lUus. Revised. See page 3. Cloth, 3.00; Leather, 3,50 W^ells. Compend of Gynaecology. Illustrated. Cloth, x.oo Winckel's Obstetrics. A Text-book on Midwifery, includ- ing the Diseases of Childbed. By Dr. F. Winckel, Professor of Gynaecology, and Director of the Royal University Clinic for Women, in Munich. Authorized Translation, by J. Clifton Edgar, m.d.. Lecturer on Obstetrics, University Medical Col- lege, New York, with nearly 200 handsome Illustrations, the majority of which are original. 8vo. Cloth, 6.00 ; Leather, 7.00 4®* See Paget 2 to sfor list o/Neiv Manuals. STUDENTS' TEXT-BOOKS AND MANUALS. 11 Obstetrics and Gynecology: — Continued. Landis' Compeiid of Obstetrics. Illustrated, sth Edition, Enlarged. By Wells. Cloth, i.oo; Interleaved for Notes, 1.25 PATHOLOGY. HISTOLOGY, ETC. Stirling. Outlines of Practical Histology. A Manual for Students. 2d Edition. 368 Illustrations. 12010. CI0&, 3.00 Wethered. Medical Microscopy. By Frank J. Wethered, M.D., M.R.c.F. 98 Illustrations. Cloth, 2.50 Hall. Compend of General Pathology and Morbid Anat- omy. Illustrated. Cloth, i.oo; Interleaved, 1.25 Gilliana's Essentials of Pathology. A Handbook for Students. 47 Illustrations. lamo. Cloth, .75 Virchow's Post-Mortem Examinations. 3d Ed. Cloth, 1.00 PHYSICAL DIAGNOSIS. Fenwick. Student's Guide to Physical Diagnosis. 7tli Edition. 117 Illustrations. i2ino. Cloth, 2.35 Tyson's Student's Handbook of Physical Diagnosis. Illus- trated. 2d Edition. i2mo. Cloth, 1.50 PHYSIOLOGY. Yeo'a Physiolf^y. Sixth Edition. The most Popular Stu- dents' Book. ]^ Gerald F. Yeo, h.d., f.r.c.s.. Professor of Physiology in King's College, London. Small Octavo. 254 carefiiUy printed Illustrations. With a Full Glossary and Index. See page s* Cloth, 3.00; Leather, 3.50 Brubaker's Compend of Physiology. Illustrated. Seventh Edition. Cloth, i.oo; Interleaved for Notes, 1.25 Kirke's Physioloey. New 13th Ed. Thoroughly Revised and Enlarged. 502 Illustrations, some of which are printed in colors. {Blakision's Authorized Edition.) Red CI. , 4.00 ; Leather, 5.00 Landois' Human Physiology. Including Histology and Micro- scopical Anatomy, and with special reference to Practical Medi- cine. Fourth Edition. Translated and Edited by Prof. StirUng. 845 Illustrations. Cloth, 7.00; Lea&er, 8.00 *' With this Text-book at his command, no student could fail in his examination." — Lancet. PRACTICE. Taylor. Practice of Medicine. A Mamial. By Frederick Taylor, h.d.. Physician to, and Lecturer on Medicine at, Guy's Hospital, London ; Physician to Evelina Hospital for Sick Chil- dren, and Examiner m Materia Medica and Pharmaceutical Chemisyy, University of London. Cloth, 2.00; Leather, 2.50 -•*" See Paget 14 and IS for list of f Quiz-Compends f 12 STUDENTS' TEXT-BOOKS ANB MANUALS. Practice : — Continued, Roberts' Practice. Revised Edition. A Handbook of the Theory and Practice of Medicine, By FreBerick T, Roberts, M.D., M.R.C.F., Professor of Clinical Medicine and Therapeutics in University College Hospital, London. Seventh Edition. Octavo. Cloth, 5.50; Sheep, 6.50 Hughes. Compend of the Practice of Medicine. 5th Edi- tion. Two parts, each. Cloth, 1.00; Interleaved for Notes, 1,25 Part i. — Continued, Eruptive and Periodical Fevers, Diseases of the Stomach, Intestines, Peritoneum, Biliary Passages, Liver, Kidneys, etc., and General Diseases, etc. Part ii. — Diseases of the Respiratory System, Circulatory System, and Nervous System; Diseases of the Blood, etc. Physicians* Edition. Fifth Edition. Including a Section on Skin Diseases, With Index, i vol. Full Morocco, Gilt, z. 50 From John A. Robinson, M.D., Assistant to Ckair of Clinical Medicine f now Lecturer on Materia Medica, Rush Medical Col- lect Chicago. "Meets with my hearty approbation as a substitute for the ordinary note books almost universally used by medical students. It is concise, accurate, well arranged, and lucid, . . . just the thing for students to use while studying physical diagnosis and the more practical departments of medicine. PRESCRIPTION BOOKS. Wythe's Dose and Symptom Book. Containing the Doses and Uses of all the principal Articles of the Materia Medica, etc. Seventeenth Edition. Completely Revised and Rewritten. Just Ready. 32mo, Cloth, i. 00; Pocket-book style, 1.25 Pereira's Physician's Prescription Book. Containing Lists of Terms, Phrases, Contractions, and Abbreviations used in Prescriptions, Explanatory Notes, Grammatfical Construction of Prescriptions, etc., etc. By Professor Jonathan Pereira,'M.D. Sixteenth Edition, samo. Cloth, 1.00; Pocket-book style, 1,25 PHARMACY. Stewart's Compend of Pharmacy. Based upon Remington's Text-book of Pharmacy. Fourth Edition, Revised in accordance with new U, S P. Clothe i.oo ; Interleaved for Notes, 1.25 Robinson. Latin Grammar of Pharmacy and Medicine. By H, D. Robinson, ph.d.. Professor of Latin Language and Literature, University of Kansas, Lawrence. With an Intro- duction by L. E. Sayre, ph.g.. Professor of Pharmacy in, and Dean of, the Dept. of Pharmacy, University of Kansas. i2mo. Second Edition. Cloth 2.00 SKIN DISEASES. Crocker. Diseases of the Skin, their Description, Pathology, Diagnosis, and Treatment, with Special Reference to the Skin > ruptions of Children. By H. Radcliife Crocker, p.r.c.p., Phy- sician for Diseases of the Skin in University College Hospital. Second Edition. Revised and Enlarged, with 92 Wood-cuts. Cloth, 5.00 Van Harlingen on Skin Diseases. A Handbook of the Dis- eases of the Skin. By Arthur Van Harlingen, m.d. 3d Edition. Enlarged and Illustrated. i2mo. /« Press. 9^ See pages 2 to S for list of New Manuals. STUDENTS' TEXT-BOOKS AND MANUALS. 13 SURGERY AND BANDAGING. Moullin*s Surj^er^T) by Hamilton. 600 Illustrations (some colored), 200 of which are original. Second Edition. Cloth, net, 7.00; Leather, net, 8.00; Half Russia, net, g.oo *«* Complete circulars, with sample pages and Illustrations, &ee upon application. Jacobson. Operations in Surgery. A Systematic Handbook for Physicians, Students, and Hospital Suigeons, By W. H. A. Jacobson, b.a. Oxon., F.R.q.s. Eng.; Ass't Surgeon Guy's Hos- pital ; Surgeon at Royal Hospital for Children and Women, etc. 199 Illustrations. zao6 pages. 8vo. Clodi. 5.00; Leather, 6.00 Heath's Minor Surgery, and Bandaging. Tenth Edition. 158 Illustrations. 62 Formube, and Diet Lists. Cloth, 2.00 Horw^itz's Compend of Surgery, Minor Surgery and Bandaging, Amputations, Fractures, Dislocations, Surgical Diseases, and the Latest Antiseptic Rules, etc., with Differential Diagnosis and Treatment. By Okvillb Horwitz, b.s., m.d.. Demonstrator of Surgery, Jefferson Medical College. 5th Edition. - Enlarged and Rearranged. Many new Illustrations and Formulae, lamo. Cloth, z.oo ; Interleaved for the addition of Notes, 1.25 *#* The new Section on Bandaging and Surgical Dressings con- sists of 32 Pages and 41 Illustrations, Every Bandage of any importance is figured. This, with the Section on Ligation of Arteries, forms an ample Text-book for the Surgical Laboratory. Walsham. Manual of Practical Surgeiy^. Third Edition, Bv Wm. T. Walsham. m.d.,f.r.c.s., Asst. Surg, to, and Dem- of Practical Surg, in, St, Bartholomew's Hospital; Surgeon to Metropolitan Free Hospital, London. With 318 Engravings, See page 2. Cloth, 3.00; Leather, 3.50 URINE, URINARY ORGANS, ETC. Holland. The Urine, and Common Poisons and The Milk. Chemical and Microscopical, for Laboratory Use. Illus- trated. Fourth Edition. i2mo. Interleaved, Cloth, i.oo Ralfe, Kidney Diseases and Urinary Derangements. 42 Illus- trations. i2mo. 572 pages. Cloth, 2. 75 Marshall and Smith. On the Urine. The Chemical Analysis ot the Urine. Colored Plates. i2mo. Cloth, 1,00 Memminger. Diagnosis by the Urine, Illus. Cloth, 1,00 Tyson. On the Urine. A Practical Guide to the Examination of Urine. With Colored Plates and Wood Engravings. Eighth Edition, Enlarged. i2mo- Cloth, 1.50 Van Ntiys, Urine Analysis. Illus. Cloth, x.oo VENEREAL DISEASES. Hill and Cooper. Student's Manual of Venereal Diseases, with PormulsB. Fourth Edition. z2mo. Cloth, 1.00 4®" See pages 14 and is for list of t Quit- Compends f PQUIZ-COMPENDS? The Best Compends for Students' Use in the Quiz Class, and when Pre- paring for Examinations. Compiled in accordance with the latest teachings of promt' nent Lecturers and the most popular Text-books. They form a most complete, practical, and exhaustive set of manuals, containing information nowhere else col- lected in such a condensed, practical shape. Thoroughly up to the times in every respect, containing many new prescriptions and formulse, and over six hundred iUustra- tions, many of which have been drawn and engraved specially for this series. The authors have had large ex- perience as quiz-masters and attaches of college, with exceptional opportunities for noting the most recent ad- vances and methods. Cloth, each $z.oo. Interleaved for Notes, $1.25. No. X. HUMAN ANATOMY, " Based upon Gray." Fifth Enlarged Edition, including Visceral Anatomy, formerly published separately. 16 Lithograph Plates, New Tables, and X17 other Illustrations. By Samuel O. L. PoiTER, M.A., M.D., M.R.c.p. (Lond,), late A. A. Surgeon U, S. Army, Professor of Practice, Cooper Medical College, San Fran- cisco. Nos. 2 and 3. PRACTICE OF MEDICINE. Fourth Edi tion. B]^ Daniel £. Hughes, m.d.. Demonstrator of Clinical Medicine in Jefferson Medical College, Philadelphia. In two parts. Part I. — Continued, Eruptive, and Periodical Fevers, Diseases of the Stomach, Intestines, Peritoneum, Biliary Passages, Liver, Kidneys, etc. (including Tests for Urine), General Diseases, etc. Part II. — Diseases of the Respiratory System (including Phy- sical Diagnosis), Circulatory System, and Nervous System; Dis- eases of the Blood, etc. *#* These little books can be regarded as a full set of notes upon the Practice of Medicine, containing the Synonyms, Definitions, Causes, Symptoms, Prognosis, Diagnosis, Treatment, etc., of each disease, and including a number of prescriptions hitherto unpub- lished. No. 4. PHYSIOLOGY, including Embryology, Seventh Edition. By Albert P. Brubaker, m.d.. Prof, of Physiology, Penn'a College of Dental Surgery; Demonstrator of Physiology in Jefferson Medical College, Philadelphia.' Revised, Enlarged, with new Illustrations. No. 5. OBSTETRICS. Illustrated. Fifth Edition, By Henry G. Landis, m.d. Edited by William H. Wells, m.d.. Assistant Demonstrator of Clinical Obstetrics, Jefferson College, Philadelphia. New Illustrations. BLAKISTON'S ? QUIZ-COMPENDS ? No. 6. MATERIA MEDICA, THERAPEUTICS, AND PRESCRIPTION WRITING. Fifth Revised Edition. With especial Reference to the Physiological Action of Drugs, and a complete article on Prescription Writing. Based on me Last Revision of the U. S. Fharmacopceia, and including many unofficinal remedies. By Samuel O. L. Potter, m.a., m.d., M.R.c.P. (Lond.), late A. A. Surg. U. S. Army ; Prof, of Practice, Cooper Medical College, San Francisco. Improved and Enlarged, with Index. No. 7. GYNECOLOGY. A Compend oi Diseases of Women. By Wm. H. Wells, h.d., Ass't Demonstrator of Obstetrics, Jefferson Medical College, Philadelphia. Illustrated. No, 8. DISEASES OF THE EYE AND REFRACTION, including Treatment and Surgery. By L. Webster Fox, h.d.. Chief CUnical Assistant Ophthalmological Dept., Jefferson Med- ical College, etc., and Geo. M. Gould, h.d. 71 Illustrations, 39 Formulae. Second Enlarged and Improved Edition. Index. No. g. SURGERY, Minor Surgery and Bandaging. Illus- trated. Fifth Edition. Including Fractures, Wounds, Dislocations, Sprains, Amputations, and other operatipns; Inflam- mation, Suppuration, Ulcers, Syphilis, Tumors, Shock, etc. Diseases of the Spine, Ear, Bladder, Testicles, Anus, and other Surgical Diseases. By Orville Horwxtz, a.h., m.d.. Demonstrator of Surgery, Jefferson Medical College. Revised and Enlarged. 98 Formulae and 167 Illustrations, No. 10. CHEMISTRY. Inorganic and Organic. For Medical and Dental Students. Including Urinary Analysis and Medical Chemistry. By Hbnrt Leffhann, m.d.. Prof, of Chemistry in Penn'a College of Dental Surgery, Phila. Third Edition, Revised and Rewritten, with Index. No. XI. PHARMACY. Based upon " Remington's Text-book of Pharmacy." By F. E. Stewart, h.d., ph.g., Quiz-Master at Philadelphia College of Pharmacy. Fourth Edition, Revised. No. 13. VETERINARY ANATOMY AND PHYSIOL- OGY. 29 Illustrations. By Wh. R. Ballou, h.d.. Prof, of Equine Anatomy at N. Y. College of Veterinary Surgeons. No. 13. DENTAL PATHOLOGY AND DENTAL MEDI- CINE. Containing all the most noteworthy points of interest to the Dental student. Second Edition. By Geo. W. Warren, D.D.S., Clinical Chief, Penn'a College of Dental Surgery, Phila- delphia. Second Edition, Enlarged and Illustrated. No. 14. DISEASES OF CHILDREN. By Dr. Marcus P. Hatfield; Prof, of Diseases of Children, Chicago Medical College. Colored Plate. No. 15. GENERAL PATHOLOGY AND MORBID ANATOMY. By H. Newbery Hall. m. d., Professorof Pathology and Medical Chemistry Post-Graduate School; Sur- geon Emergency Hospital, Chicago, etc. 91 Illustrations, Booad la Cloth, $1. InterleaTed, for the Addition of 27otes, $1.25. Jt^' ^0 series of books are so complete in detail^ concise in language^ or so well printed and bound. Each one forms a complete set of notes upon the subject under con- sideration. Illustrated Descriptive Circular Free. 25,000 COPIES Of These Books Have Already Been Sold. GOULD'S NEW Medical Dictionary. Based on Becent Medical Iiiterature. Small 8vo, Half Morocco, as above, with Thumb Index, . , $4.23 Plain Dark Leather, without Thumb Index, 3.25 A compact, concise Vocabulary, including all the Words and Phrases used in medicine, with their proper Pronunciation and Definitions. "One pleasing feature of the book is that the reader can almost invariably find the definition under the word he looks for, without being referred from one place to another, as is too commonly the case in medical dictionaries. The tables of the bacilli, micrococci, leucomaines and ptomaines are excellent, and contain a large amount of information in a limited space. The anatomical tallies are also concise and clear. . . . We should unhesitatingly recommend this dictionary to our readers, feeling sure that it will prove of much value to them." — American Journal of Medical Science. JUST PUBLISHED. GOULD'S POCKET DICTIONARY, 12,000 Medical Words Pronounced and Defined. Leather, gilt edges, $1.00; with Thumb Index, ^1.25 ■^>ifi..;v:.r-?--:^ -;?- M^->^.i.l"