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 Essentials of physics and chemistry writ 
 
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 Library 
 
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 http://www.archive.org/details/cu31924031267754 
 
BY THE SAME AUTHOR. 
 
 Manual of Differential Medical Diagnosis. (In 
 
 Students' Manuals Series.) i6mo. cloth, $1.25 
 
 Differential Diagnosis of the Diseases of the Skin. 
 
 (In Students' Manuals Series.) i6mo, cloth, $1.25 
 
 G. P. PUTNAM'S SONS, New York and London. 
 
ESSENTIALS OF 
 PHYSICS AND CHEMISTRY 
 
 WRITTEN ESPECIALLY FOR THE USE OF STUDENTS 
 IN MEDICINE 
 
 CONDICT W. CUTLER, M.S., M.D. 
 
 PHYSICIAN-IN-CHIEF OF THE NEW YORK DISPENSARY ; INSTRUCTOR IN DISEASES OF THE 
 SKIN AT THE NEW YORK POST-GRADUATE SCHOOL AND HOSPITAL ; ASSISTANT 
 SURGEON FOR VENEREAL AND SKIN DISEASES AT THE NEW YORK 
 HOSPITAL, OUT-DOOR DEPARTMENT ; AUTHOR OF " DIFFER- 
 ENTIAL MEDICAL DIAGNOSIS," " DIFFERENTIAL 
 DIAGNOSIS OF THE DISEASES OF 
 THE SKIN," ETC., ETC, 
 
 THIRD EDITION, ENLARGED AND REVISED 
 
 NEW YORK AND LONDON 
 
 G. P. PUTNAM'S SONS 
 
 18S9 
 
 E.V. 
 
Copyright by 
 
 CONDICT W. CUTLER 
 
 1888 
 
 P.B. 
 
 Press of 
 
 G. P. Putnam's Sons 
 
 New York 
 
TO 
 
 MEDICAL STUDENTS 
 
 IN RECOLLECTION OF MY OWN STUDENT DAYS 
 
 AND IN EARNEST DESIRE TO ASSIST 
 
 THOSE ACTIVELY ENGAGED IN THE STUDY OF MEDICINE 
 
 THIS VOLUME IS GLADLY 
 
 INSCRIBED 
 
PREFACE TO THE THIRD EDITION. 
 
 These essentials of physics and chemistry are not in- 
 tended to take the place of such standard text-books as 
 Ganot and Fownes, but simply to aid the student in pre- 
 paring for "quiz" or examination. In preparing 'my 
 students for examination, I have felt the need of some 
 such little work that I could recommend to them for a 
 general review or recapitulation of the ground covered in 
 lecture or " quiz." When a student myself, and in active 
 preparation for examination, some such essentials would 
 have been of the greatest assistance, for although having 
 faithfully studied my text-books on physics and chemis- 
 try, when taking them up for a final general review 1 
 could not help thinking how many shells I must crack to 
 obtain the small amount of meat required. For the time 
 spent in digging out this meat and presenting it in a 
 palatable form, I now feel amply rewarded by the favor 
 with which this book has been received by students, — 
 especially medical students, for whom it was originally 
 written. 
 
 This third edition has been changed by the addition of 
 new matter and thorough revision of the old, which will, I 
 trust, together with the different form and shape of the 
 book, add to its merits and insure its continued favor 
 with my friends — the students. 
 150 West 53d St., New York. 
 
CONTENTS. 
 
 PART I.— PHYSICS. 
 
 MATTER. 
 
 CHAPTER PAGE 
 
 I — Matter 3 
 
 II — Simple Machines 7 
 
 III — Liquids . . . .* 8 
 
 IV — Gases 10 
 
 V — Sound 14 
 
 HEAT. 
 
 VI — Thermometers, etc 15 
 
 VII — Expansion 19 
 
 VIII — Fusion and Latent Heat 20 
 
 IX — ^Vapors 22 
 
 X — Hygrometry 24 
 
 XI — Transmission of Heat 26 
 
 XII — Calorimetry 28 
 
 XIII — Sources of Heat and Cold 30 
 
 XIV — Mechanical Equivalent of Heat .... 32 
 
 LIGHT. 
 
 XV — Propagation of Light, etc. 33 
 
 XVI — Intensity of Light 35 
 
 XVII — Reflection of Light 36 
 
 XVIII — Refraction of Light 39 
 
 XIX — Transmission of Light 41 
 
 XX — Dispersion and Achromation of Light ... 43 
 
 XXI — Optical Instruments 48 
 
 XXII — Photography 50 
 
 vii 
 
viii Contents. 
 
 TAGS 
 
 XXIII — Double Refraction 53 
 
 XXIV — Sources of Light 57 
 
 ELECTRICITY AND MAGNETISM. 
 
 XXV— Magnetism 58 
 
 XXVI — Theories of Electricity, etc 61 
 
 XXVII — Statical Electricity 62 
 
 XXVIII — Electrical Machines 64 
 
 XXIX — Effects of Electrical Discharge .... 67 
 
 XXX — Dynamical Electricity 69 
 
 XXXI — Chemical Batteries 71 
 
 XXXII — Attachments to a Battery 75 
 
 XXXIII — Intensity and Resistance of Electro-Motor Force 77 
 
 XXXIV — Effects of Current Electricity .... 79 
 
 XXXV — Electro-Dynamics 82 
 
 XXXVI — ^Voltaic Induction • 84 
 
 XXXVII — Thermo-Electric Currents 89 
 
 PART II.— THEORETICAL CHEMISTRY. 
 
 Theoretical Chemistry 
 
 91 
 
 PART III.— INORGANIC CHEMISTRY. 
 
 I — Hydrogen m 
 
 II — Oxygen 113 
 
 III — Nitrogen 122 
 
 rv — Carbon 130 
 
 V — Combustion 138 
 
 VI — Halogens 141 
 
 VII — Sulphur 151 
 
 VIII — Silicon and Boron i5g 
 
 IX — Phosphorus 164 
 
 X — Alkaline Metals 170 
 
Contents. ix 
 
 PAGE 
 
 XI — Alkaline Earths 175 
 
 XII — Tin, Zinc, and Cadmium 179 
 
 XIII — Lead, Copper, and Mercury ■ 184 
 
 XIV — Platinum, Gold, and Silver 189 
 
 XV — Chromium, Manganese, and Aluminum . . . 192 
 
 XVI — Iron, Cobalt, and Nickel ig6 
 
 XVII — Arsenic igg 
 
 XVIII — Antimony and Bismuth 203 
 
 PART IV.— ORGANIC CHEMISTRY. 
 
 I — Introduction 209 
 
 II — Fatty Groups — Hydrocarbons 211 
 
 III — Methane Compounds and Derivatives . . . 213 
 
 IV — Hydroxyl Substitution 216 
 
 V — Oxygen Substitutions 220 
 
 VI — Sulphur Substitutions 222 
 
 VII — Nitrogen Substitutions 224 
 
 VIII — Phosphorous and Metallic Substitutions . . 229 
 
 IX — Ethane Compounds 232 
 
 X — Hydroxyl Substitutions 234 
 
 XI — Sulphur and other Substitutions .... 240 
 
 XII — Propane Compounds 242 
 
 XIII — Hydroxyl Substitutions 244 
 
 XIV — Butane Compounds 250 
 
 XV — Pentane and Hexane Compounds .... 253 
 
 XVI— Oils and Fats 256 
 
 XVII — Carbohydrates 258 
 
 XVIII — Fermentation 262 
 
 XIX— Aromatic Group 265 
 
 XX — Benzine Derivatives 267 
 
 XXI — Hydrocarbon Substitutions of Benzine . . . 271 
 
 XXII — Aromatic Groups of Organic Compounds . . 276 
 
 XXIII— Alkaloids 279 
 
 XXIV— Animal Chemistry 281 
 
PART I, 
 PHYSICS. 
 
MATTER. 
 
 CHAPTER I. 
 
 Physics treats of the phenomena presented to us by- 
 matter. 
 
 Matter is any thing we can appreciate by our senses, 
 and is made up of sixty-six elements or substances that 
 cannot be dividdd into other substances. 
 
 PROPERTIES OF MATTER. 
 
 The properties of matter may be divided into two 
 classes : 
 
 General. 
 
 Specific. 
 
 A. General properties of matter are those common to 
 all matter, and are six in number, viz. : 
 
 a. Impenetrability. The property of occupying space 
 exclusively. 
 
 b. Extension or volume. The space matter occupies. 
 
 c. Form. The definite shape of matter. 
 
 d. Indestructibility. The inability to destroy matter, 
 even though it may change its form. 
 
 e. Inertia. The inability of matter to put itself in 
 motion when at rest or of coming to rest when in motion. 
 
 f. Divisibility. That property which allows matter to 
 be separated into parts. 
 
 3 
 
/ < 
 
 4 Physics. 
 
 B. The Specific Properties of matter are those which 
 serve to distinguish one form of matter from another, 
 the following being among the most important of such 
 properties : 
 
 a. Ductility. That property of matter which admits 
 of its being drawn into a wire. 
 
 b. Malleability. The ability of matter to be rolled or 
 hammered into sheets. 
 
 c. Tenacity. Inability of matter to be readily pulled 
 apart. 
 
 d. Hardness. Matter is hard when it is not easily in- 
 dented or scratched. 
 
 e. Elasticity. The tendency of matter to return to its 
 original form or volume when the force that altered its 
 shape ceases to act. 
 
 DIVISION OF MATTER. 
 
 Matter may be divided into : 
 
 Atoms. 
 
 Molecules. 
 
 Masses. 
 
 a. Atoms are the smallest divisions of matter, and two 
 or more may unite to form molecules. 
 
 b. A molecule is the smallest group of atoms that will 
 exhibit the physical and chemical properties of the sub- 
 stance, and cannot be divided without losing these char- 
 acteristics. 
 
 c. A mass is a collection of molecules. 
 
 Molecules present themselves in three different states, 
 as : 
 Solids. 
 Liquids. 
 Gases. 
 
Matter. . 5 
 
 a. In a solid state the molecules are naturally in a fixed 
 condition, and as a consequence solid bodies tend to re- 
 tain a given form. 
 
 b. In the liquid state the molecules move freely upon 
 each other. 
 
 c. In the gaseous state the molecules tend to repel each 
 other or to occupy greater space. 
 
 FORCES GOVERNING MATTER. 
 
 1. Force controlling atoms. 
 
 Chemical affinity, or that force which causes atoms to 
 combine or to remain combined. 
 
 2. Forces controlling molecules : 
 Cohesion. 
 
 Adhesion. 
 
 Repulsion. 
 
 Polarity. 
 
 a. Cohesion is that force which unites molecules to 
 form masses. 
 
 b. Adhesion is the molecular force which binds to- 
 gether the surfaces of two or more masses. 
 
 Capillary attraction is that form of adhesion which takes 
 place between solids and liquids, as between water and 
 glass. 
 
 c. Repulsion is that force which causes molecules to 
 occupy more space. 
 
 d. Polarity is that force which unites molecules to 
 form crystals. 
 
 3. Force controlling masses. 
 
 Gravitation is the force attracting masses to each other, 
 and is governed by the following law : — 
 
 The attraction is directly in proportion to the mass and 
 inversely as the square of the distance. 
 
6 Physics 
 
 Gravity is the force exerted by the earth upon a body, 
 and represents weight. 
 
 SPECIFIC GRAVITY. 
 
 specific gravity or density is comparative weight. 
 
 The standards for comparison are — for liquids and 
 solids, water at a temperature of 60° F., and iox gases and 
 vapors, air or hydrogen. 
 
 The principle by which we obtain the specific gravities 
 of substances depends upon the law of Archimedes : — 
 A body immersed in a liquid loses weight equal to the weight 
 of the liquid displaced. 
 
CHAPTER II. 
 
 SIMPLE MACHINES. 
 
 There are six simple machines upon the principles of 
 which all machinery is constructed. They are : 
 
 The lever. 
 
 The inclined plane. 
 
 The wheel and axle. 
 
 The screw. 
 
 The wedge. 
 
 The pulley. 
 
 The lever is the only machine, the principle of which 
 plays an important part in the human mechanism — the 
 bones representing the levers. 
 
 The lever is a bar turning on a pivot. The force used 
 is called the power (P), the object lifted the weight (W), 
 and the pivot the fulcrum (F). There are three kinds of 
 levers : 
 
 a. F being between P and W. 
 
 b. W being between F and P. 
 
 c. P being between W and F. 
 
 In the first and second class of levers power is gained 
 and time lost, but in the third class time is gained and 
 power lost. 
 
 In all forms of levers the distance between F and the P 
 and W is called the arms of the lever, and the power is to 
 the weight as the length of the weight arm is to the length 
 of the power arm. 
 
 7 
 
CHAPTER III. 
 
 LIQUIDS. 
 
 Liquids are but slightly compressible and according to 
 Pascal's law — Pressure is transmitted undiminished in all 
 directions with the same force, and at right angles to all 
 equal surfaces. 
 
 It is on the principle of Pascal's law that the hydraulic 
 press is constructed. This consists of two cylinders, the 
 area of the piston of one being much greater than that of 
 the other. Water is driven by means of the piston from 
 the small cylinder into the large one, and the pressure of 
 the water upon the large piston will be as much greater 
 than that upon the small one, as the area of the base of 
 the large piston exceeds that of the small. 
 
 1. Means of obtaining specific gravity of solids. 
 
 By hydrostatic balance. Weigh the substance first in air, 
 then in water, and divide its weight in air by its loss of 
 weight in water. The result is its specific gravity. 
 
 If the solid is lighter than water — divide its weight by 
 its weight added to the loss it causes a heavier body 
 previously weighed in water. 
 
 2. Of liquids. 
 
 a. By the specific-gravity bottle. 
 
 Subtract the weight of the bottle from the weight of 
 the bottle filled with water, and then from the weight of 
 the bottle filled with the liquid, and divide the latter by 
 the former. The result is its specific gravity. 
 
Matter. 
 
 9 
 
 b. By the hydrometer, which consists of a graduated 
 glass tube loaded at the bottom with mercury so it may 
 sink to a certain depth in fluids, the depth depending 
 upon the specific gravity of the substance. 
 
 The instruments are known under different names, as 
 lactometer, urinometer, alcoholometer, etc., the name 
 signifying the kind of liquids for which they are used. 
 The graduation of the instrument differs according as the 
 liquid is heavier or lighter than water, which is usually, 
 called looo. Thus milk has a specific gravity of 1029, 
 urine 1022, both being heavier than water. The last two 
 figures in the specific gravity represent, approximately, 
 the number of grains of solid matter to each fluid ounce 
 of the substance. 
 
CHAPTER" IV. 
 
 GASES. 
 
 I 
 
 In gases the molecules tend to expand or repel each 
 other. Otto Degarager first established the fact that gases 
 had weight. 
 
 The pressure or weight of the atmosphere at the level 
 of the sea is about fifteen pounds to the square inch, but 
 diminishes proportionally as we ascend. 
 
 Torricellt s experiment. 
 
 Torricelli first determined the pressure of the atmos- 
 phere by taking a glass tube sealed at one end, filling it 
 with mercury, and inverting it by placing the open end 
 covered with the thumb in a vessel of mercury. 
 
 He found by this experiment that the mercury in the 
 tube remained about thirty inches above the level of the 
 mercury in the vessel, and the weight of this mercury 
 represented the pressure of the atmosphere to be in the 
 proportion of fifteen pounds to the square inch. 
 
 The Torricellian vacuum is the space above the mercury 
 in the tube. 
 
 Pascal determined that the height of the mercury in 
 the tube really did depend upon the pressure of the 
 atmosphere, for performing the same experiment on a 
 high mountain, he found the mercury did not remain so 
 high. 
 
 BAROMETERS. 
 
 Barometers are instruments used for measuring atmos- 
 pheric pressure. 
 
Matter. 1 1 
 
 Many of them are based on the principle of Torricelli's 
 experiment — the pressure of the atmosphere being meas- 
 ured by the height of a column of mercury. 
 
 MERCURY BAROMETERS. 
 The simplest form of a mercury barometer consists of a 
 Torricellian tube about 32 inches in length, filled with 
 and inverted into a basin of mercury. This tube is fur- 
 nished with a graduated scale divided into tenths of 
 inches, so as to enable the observer to readily detect 
 slight fluctuations in the height of the mercury column. 
 At ordinary temperatures and at the level of the sea the 
 column of mercury will measure about 30 inches. 
 
 BAROMETRIC CORRECTIONS. 
 Corrections have to be made in mercury barometers 
 for: 
 
 Temperature. 
 Elevation. 
 Capillarity. 
 State of weather. 
 
 a. Temperature. Heat causes an expansion of the 
 mercury and a rise in the barometer, while cold has the 
 opposite effect. 
 
 b. Elevation. At the level of the sea the column of 
 mercury measures about 30 inches, but falls about one 
 tenth of an inch for every 87.2 feet of ascent. On account 
 of the change of temperature and diminished density of 
 the atmosphere as we ascend, the barometric fall is not 
 strictly uniform. 
 
 c. Capillarity causes the mercury to adhere to the y 
 sides of the tube. 
 
 d. In dry weather the atmosphere is dense, and conse- 
 
12 Physics. 
 
 quently the pressure on the mercury causes it to stand 
 higher than it does in wet weather, when the air is rarer 
 and contains more aqueous vapor. 
 
 A storm can usually be predicted by the fall in the 
 barometer. 
 
 BAROMETRIC VARIATIONS. 
 
 The barometer does not stand at the same height at all 
 latitudes. It increases from the equator to 40° latitude, 
 where it reaches its maximum height of 30.04 inches, and 
 then diminishes from there toward the poles. 
 
 There are also daily variations in the barometer, most 
 marked at the equator, where it reaches its maximum 
 height at 10 and its minimum at 4 o'clock. 
 
 AIR BAROMETERS. 
 
 Besides fluid barometers there are air barometers, 
 Aneroid's being a good example. 
 
 This consists of a thin metallic box, exhausted of air, 
 the top of which is so thin that it yields readily to altera- 
 tions in the pressure of the atmosphere. These altera- 
 tions are transmitted by levers to an index which indicates 
 the pressure on a scale. 
 
 LAW OF GASES. 
 
 a. Boyle's law : The volume of a gas is inversely as 
 the pressure. 
 
 b. The rapidity with which gases mix is inversely as the 
 square root of their density. 
 
 c. The density of a gas is directly as the pressure. 
 
 d. Law of Avogadro. Equal volumes of gases at the 
 same temperature contain the same number of molecules. 
 
Matter. 1 3 
 
 SPECIFIC GRAVITY OF GASES. 
 
 Weigh the same volume of air and the gas and divide 
 the weight of the gas by that of the air. The result is the 
 specific gravity of the gas. 
 
 AIR PUMPS. 
 
 The principle of the air pump depends upon the expan- 
 sive or repulsive property of gases. 
 
 We take away a portion of air and the remainder ex- 
 pands so as to fill up the whole space. 
 
 In this way the air becomes greatly rarefied, but an ab- 
 solute vacuum cannot be produced. 
 
 In Sprengel's air pump which depends upon the princi- 
 ple of converting the space to be exhausted into a Torri- 
 cellian vacuum, falling mercury passes the aperture of the 
 vessel to be exhausted of the gas. 
 
 The gas, as it were, is entangled in the falling mercury 
 and in this way a nearly complete vacuum is produced. 
 
 It is on the principle of Sprengel's air pump, that traps 
 in water pipes are syphoned, thus leaving the pipes free to 
 allow the passage of sewer gas. ,_^ , /~rcj 
 
 ^^^. ^U-^ cty^-^^'^J^i. ^Tt/t^^ '^ a.<^^^'^<^ 
 
i CHAPTER V. 
 
 SOUND. 
 
 Impressions which the mind receives through the organ 
 of hearing is called sound. For the production of sound 
 it is necessary that the object producing it should be set 
 in vibration and that it be surrounded by media such as 
 air, water, etc., to carry these vibrations to the ear. 
 
 Velocity of sound. In the air sound travels at the rate 
 of about iioo feet per second. As temperature increases 
 the velocity of sound about one foot per second for every 
 degree of rise, therefore sounds travel more rapidly in 
 summer than in winter. Sound travels in water about 
 four times faster than it does in air. 
 
 Echo is the reflection of sound from any surface. If the 
 sound and its echo reach the ear within one sixteenth of 
 a second they seem as one, hence an echo is not appre- 
 ciated unless the surface producing it is more than thirty- 
 five feet from the source of the sound. 
 
 Pitch is the acuteness of sound, and depends entirely 
 upon the rapidity of the vibrations — the greater the num- 
 ber of vibrations the higher the pitch. Sixteen vibrations 
 per second produces the lowest and about 33,000 the 
 highest number of vibrations appreciable to the ear. 
 
 Intensity of sound is its loudness, and depends upon the 
 j<; properties of the sonorous bodies and the media by which 
 the sound is carried. 
 
 The rarer the media the less intense will be the sound. 
 
 Quality of sound is its peculiarity which distinguishes it 
 from other sounds, and depends upon the physical prop- 
 erties of the sonorous body. 
 
 14 
 
HEAT. 
 
 CHx\PTER VI. 
 
 Theories. 
 
 1. Emission theory : Heat is considered an imponder- 
 able fluid which surrounds all molecules, and the entrance 
 of this fluid into substances causes heat, and its egress cold. 
 
 2. Undulatory theory : Heat is due to a rapid vibra- 
 tory movement of the molecules of any substance. That all 
 space is filled with an imponderable ether, which hot 
 bodies set in rapid vibration, thus communicating a more 
 rapid vibration to the molecules of adjacent substances. 
 
 This theory is the one generally adopted. 
 
 TEMPERATURE. 
 
 Heat causes all substances to expand ; hence by the 
 different expansive qualities of liquids, solids, and gases, 
 we can measure temperature. 
 
 Temperature is the greater or less extent a substance 
 tends to impart sensible heat to other substances. 
 
 THERMOMETERS. 
 Thermometers are instruments used for measuring 
 temperatures, and whose principle depends upon the 
 contraction and expansion of substances. They usually 
 consist of a glass tube and bulb filled with some fluid 
 substance, and then hermetically sealed and graduated. 
 
 15 
 
1 6 Physics. 
 
 But beside the liquid thermometers, air and solid (pyrom- 
 eters) thermometers are also constructed. 
 
 Liquid thermometers are generally used — mercury and 
 alcohol being the best suited for this purpose. Mercury, 
 because it boils only at a very high temperature, and has 
 a nearly uniform rate of expansion ; and alcohol, because 
 it does not freeze even at the lowest temperatures. 
 
 MERCURY THERMOMETERS. 
 In constructing an ordinary mercury thermometer, two 
 fixed points are determined for graduation — viz. : 
 
 a. Boiling point of water at the level of the sea. 
 
 b. Freezing point of water. 
 
 As these two temperatures are constant and the expan- 
 sion of mercury is nearly uniform, the graduation of the 
 thermometer is accomplished by dividing the space be- 
 tween the freezing and boiling points of water into an 
 equal number of parts called degrees. 
 
 The size of these degrees differs in various countries. 
 
 In this country the Fahrenheit scale is used — freezing 
 point 32°, boiling point 212°. 
 
 In France and on the Continent generally, the Centi- 
 grade scale — freezing point taken as 0°, and boiling point 
 100°. 
 
 In some portions of Germany the Reaumur scale is 
 chiefly used — the freezing point being 0°, while the foiling 
 point is taken at 80°. 
 
 CONVERSION OF DEGREES. 
 
 1. Fahrenheit to Centigrade. 
 
 (F - 32°) I = C. 
 
 2. Fahrenheit to Reaumur. 
 
 (F - 32°) i = R. 
 
Heat. 17 
 
 61 
 
 Centigrade to Reaumur. 
 
 fC = R. 
 Centigrade to Fahrenheit. 
 
 I C + 32 = F. 
 Reaumur to Fahrenheit. 
 
 f R + 32 = F. 
 Reaumur to Centigrade. 
 
 iR = C. 
 
 ALCOHOL THERMOMETERS. 
 
 Alcohol thermometers are used for determining low 
 temperatures only, for alcohol boils at 78° C, and as it 
 nears the boiling point it expands very irregularly, thus 
 destroying its accuracy for high temperatures. As mer- 
 cury freezes at.40'^ C, and alcohol does not freeze at the 
 lowest temperatures, it is here that alcohol thermometers 
 are found so useful. 
 
 They are graduated by means of comparison with the 
 mercury thermometer at different degrees of temperature. 
 
 AIR THERMOMETERS. 
 
 Air thermometers are so constructed that they contain 
 both air and fluid, the principles of which are based on the 
 expansion of air by increase of temperature. This expan- 
 sion is noted by the rise and fall of a colored liquid in the 
 tube of the thermometer. The graduation of the scale 
 is made by comparing the position of the fluid with the 
 indications of a mercury thermometer at equal tempera- 
 tures. 
 
 Thermometers may be : 
 
 Delicate. 
 
 Accurate. 
 
1 8 Physics. 
 
 a. A delicate thermometer is one that measures rapidly- 
 very small changes of temperature. 
 
 b. A thermometer is accurate when it indicates the 
 changes of temperature correctly. 
 
 PYROMETERS. 
 
 Pyrometers are instruments used for measuring very 
 high temperatures. They are various in kind. 
 
 a. Some are made of metals that melt at a known 
 temperature. 
 
 b. Others depend upon the principle of the air ther- 
 mometer. 
 
 c. Still others on the electric thermometer — higher the 
 temperature the better the conductility. 
 
 d. While others on the expansive property of certain 
 substances at very high temperatures. 
 
CHAPTER VII. 
 
 EXPANSION. 
 
 1. Of solids. 
 
 Solids expand in three dimensions. 
 
 a. Linear. 
 
 b. Superficial. 
 
 c. Cubical. 
 
 The co-efficient of expansion is the expansion due to the 
 rise of temperature from o° to i" C. The co-efiScient of 
 expansion in solids varies to a marked degree, and from 
 this fact many applications are made. 
 
 Thus in the compensation pendulum the distance between 
 the centre of oscillation and the centre of suspension re- 
 mains constant at all temperatures by properly using 
 metals with different degrees of expansibility, in its con- 
 struction. 
 
 2. Of liquids. 
 
 The co-efficient of expansion of a liquid is the increase 
 of the unit of volume for a singly degree. 
 
 With an increase of temperature there is an increase of 
 volume. In water, however, if the temperature fall below 
 4° C, it expands till the freezing point is reached. 
 
 Hence the maximum density of water is at 4° C. 
 
 3. Of gases. 
 
 The co-efficient of expansion of a gas is its increase of 
 volume for 1° C. 
 
 This co-efficient is nearly uniform for all gases at all 
 degrees of temperature. 
 
 Gases expand -^ of their volumes for each degree of 
 Centigrade. 
 
 19 
 
CHAPTER VIII. 
 
 FUSION. 
 
 Fusion is the passage of a body from the solid into the 
 liquid state. 
 
 Every substance begins to fuse at a certain tempera- 
 ture, and that temperature remains the same until fusion 
 is complete. 
 
 All substances that expand on passing from the solid 
 to the liquid state, as the great majority do, any increase 
 in pressure will raise the melting point. The reverse is 
 true in all substances — such as ice — that contract during 
 fusion. 
 
 LATENT HEAT. 
 
 Latent heat is that heat which causes change of state or 
 fusion, and is not indicated by the thermometer. Thus 
 if one pound of water at 80° C. be mixed with one pound 
 of ice at 0° C, the result will be water at 0° C. Hence 
 it takes as much heat to melt one pound of ice as will 
 raise one pound of water 80° C. Therefore, 80° C. is called 
 the latent heat of water. 
 
 As it requires a certain amount of heat not indicated 
 by the thermometer to turn a solid into a liquid, so it 
 does to convert a liquid into a vapor. 
 
 The latent heat of evaporation or steam is 540° C, and 
 this heat has to come from surrounding substances, such 
 as heat produced by rapid combustion, etc. Hence evap- 
 orization produces cold, and by appropriate apparatus 
 water, mercury, etc., can be frozen by it. 
 
Heat. 2 1 
 
 For example, if ten pounds of water at io° C. be mixed 
 with one pound of steam at ioo° C, the temperature of 
 the mixture would be 6"]° -\- C. 
 lO X lo = lOO — Total number of degrees of tempera- 
 ture in the ten pounds of water, 
 loo X I = lOO — Temperature of the steam. 
 540 — Latent heat of steam. 
 
 740 — Total number of degrees. 
 
 740 -T- 1 1 (the number of lbs. of both water and steam) 
 = 6"]° -\- the temperature of the mixture. 
 
 During solution a quantity of heat becomes latent. It 
 is on this principle of fusion that artificial cold is pro- 
 duced. 
 
 In passing from a solid to a liquid state a certain amount 
 of heat is required, and the extraction of this heat from 
 surrounding substances lowers their temperatures. 
 
 Chemical affinity accelerates fusion, hence acid and a 
 salt or ice and salt acting in this way are better freezing 
 mixtures than a salt or ice alone would be. 
 
 Crystals. Fluids which pass slowly into the solid state 
 usually assume regular geometrical forms called crystals. 
 
CHAPTER IX. 
 
 VAPORS. 
 
 Vapors are aeriform fluids into which volatile substances 
 are changed by the absorption of heat. Vapors are trans- 
 parent and usually colorless. 
 
 Vaporization is the rapid passage of a liquid into the 
 gaseous state. 
 
 Evaporation is the slow production of vapor from the 
 free surface of a liquid. 
 
 Under ordinary conditions liquids pass but slowly into 
 the gaseous state, but in a vacuum all volatile liquids are 
 immediately converted into vapors. 
 
 Heat also hastens vaporization. 
 
 Saturated vapors. When a vapor is so dense that any 
 increase of vaporization or pressure, or any decrease of 
 temperature, will cause a portion of it to assume a liquid 
 state, the vapor is said to be saturated. 
 
 ■The higher the temperature the more vapor it takes to 
 reach the point of saturation. 
 
 Tension. The pressure exerted by a gas is called its 
 tension. The tension of a gas is measured by the pres- 
 sure it exerts on a column of mercury, and is expressed 
 in milimetres. It is obtained experimentally by evapo- 
 rating gases at different temperatures in the Torricellian 
 vacuum. Increase the temperature and the tension of a 
 gas is increased proportionally. 
 
 Boiling is the rapid production of bubbles of vapor in 
 
Heat. 
 
 23 
 
 the mass of liquid itself. Boiling takes place when the 
 tension of its vapor is equal to the pressure of the atmos- 
 phere, hence any increase in the pressure will raise the 
 boiling point, and any diminution in the pressure will 
 lower the boiling point. 
 
 The former fact is made use of in Papiris digestor. 
 
 The boiling point is the temperature at which a liquid 
 boils. 
 
 EVAPORATION. 
 
 Evaporation is aided by : 
 
 a. Heat. 
 
 b. Dryness of surrounding atmosphere. 
 
 c. Increase of surface. 
 
 d. Renewal of atmosphere. 
 
 LIQUEFACTION OF VAPORS AND GASES. 
 Liquefaction of vapors and gases is accomplished by 
 means of 
 
 a. Cold. 
 
 b. Pressure. 
 
 c. Chemical affinity. 
 
 Distillation is an example of liquefaction of vapors by 
 means of cold. All gases such as hydrogen, nitrogen 
 and " laughing gas " can be liquefied by pressure. 
 
 SPHEROIDAL CONDITION. 
 When a drop of water is thrown upon a red-hot surface,' 
 as iron, it does not boil or rapidly evaporate, but forms a 
 globule that rotates rapidly over the iron. This, is called 
 spheroidal state and is due to the globules resting upon a 
 cushion of its own vapor produced by the heat radiating 
 from the hot surface to its under surface. Many liquids 
 have a spheroidal state. 
 
CHAPTER X. 
 HYGROMETRY 
 
 Hygrometry is determining the quantity of aqueous 
 vapor contained in a given quantity of air. 
 
 The air is never saturated, but the ratio of the quantity 
 of aqueous vapor to the atmosphere when saturated is 
 called the hygrometric state. 
 
 There are a number of instruments made for determin- 
 ing this state, called hygrometers. 
 
 These are : 
 
 Chemical hygrometers. 
 
 Condensing " 
 
 Absorbing " 
 
 Psychrometers. 
 
 a. Chemical hygrometers are based on the property 
 that some substances have of absorbing all the water in 
 the air passed through them. 
 
 The substance, such as the chloride of calcium, having 
 been weighed before and after the passage of the air 
 through it, the difference in weight represents the amount 
 of aqueous vapor present. 
 
 b. Condensing hygrometers are based upon the fact 
 that if the temperature of the atmosphere is lowered, at a 
 certain degree the point of saturation will be reached, and 
 as a result moisture will be deposited. 
 
 This temperature at which the air is saturated is called 
 the dew-point. 
 
 24 
 
Heat. 
 
 25 
 
 Comparing the temperature of the surrounding at- 
 mosphere and the dew-point, and dividing the tension of 
 the atmosphere at dew-point by the tension of the sur- 
 rounding air at the given temperature, will give the 
 hygrometric state of the air. 
 
 For example : 
 
 Temperature of the air = 15° C. 
 
 " dew-point = 5° C. 
 
 Tension of the air at 15° C = 12.69 i"™- 
 S°C= 6.53 " 
 
 ■j'jS^S-j = 0.5, the hygrometric state of the air. In other 
 words, the air would be half saturated with moisture. 
 
 c. Absorption hygrometers are based upon the property 
 which some organic substances have of elongating when 
 moist, and shortening when dry. 
 
 d. The psychrometer, or wet-bulb hygrometer, is based 
 upon the fact that a fluid evaporates more rapidly in the 
 air, in proportion as the air is drier, and consequently the 
 temperature of the fiuid falls in the same proportion. 
 
 The instrument consists of two thermometers, the bulb 
 of one covered with wet muslin. 
 
 The nearer the air is to being saturated, the nearer the 
 two thermometers will indicate — the wet-bulb thermom- 
 eter always indicating the lower temperature. 
 
 The absolute amount of moisture in the atmosphere is 
 greater in summer than in winter, and at its maximum 
 about six o'clock in the morning. It varies, however, 
 much with the temperature from day to day. The dry- 
 ness of the air increases with the distance from the sea, 
 and usually with the altitude. 
 
CHAPTER XL 
 TRANSMISSION OF HEAT. 
 
 Heat is transmitted by : 
 "^' Radiation. , 
 ',tonduction. 
 i^onvection. i 
 
 a. Radiated heat is that which is transmitted to a body 
 from the source of heat without affecting the temperature 
 of the intervening medium, and its intensity is inversely as 
 the square of the distance, and directly as the temperature 
 of its source. 
 
 Bodies that transmit radiated heat readily are called 
 Diathermanic, while those that stop radiated heat, Ather- 
 manic. Bodies that absorb the most heat are the best 
 radiators, the two properties being equal. 
 
 b. Conducted heat is that which is transmitted in the 
 mass of the body itself. Bodies conduct heat with very 
 different degrees of facility. Metals are the best con- 
 ductors, while organic substances and liquids are poor 
 conductors. Gases conduct heat very little if at all. 
 
 c. Convected heat is that which is transmitted in liquids. 
 When liquids are heated at the bottom, ascending and de- 
 scending currents are produced by the heated layers be- 
 coming less dense and rising while the'denser and colder 
 layers above sink to the bottom. This method of trans- 
 mitting heat is called convection. 
 
 26 
 
Heat. 27 
 
 REFLECTION OF HEAT. 
 
 The laws governing the reflection of heat are like those 
 of light. {See chapter on light.) 
 
 Some bodies have much greater reflecting power than 
 others. Metals have the greatest and lamp-black the 
 least. 
 
 White bodies reflect heat well but absorb little ; the re- 
 verse is true of black substances. 
 
CHAPTER XII. 
 
 CALORIMETRY. 
 
 Calorimetry is the measure of the quantity of heat a 
 body loses or gains during change of state or temperature. 
 
 Quantities of heat in* substances are expressed ' by the 
 extent of their power to raise the temperature of a known 
 quantity of water. 
 
 A Thermal unit is the standard of comparison for quan- 
 tities of heat, and is the amount of heat necessary to raise 
 one pound of water i° C. 
 
 Specific heat is the quantity of heat it takes to raise dif- 
 ferent substances to the same temperature, and is deter- 
 mined in three ways: 
 
 a. By melting ice. 
 
 b. By mixtures. 
 
 c. By cooling. 
 
 The melting-ice method is based upon the fact that it 
 takes to melt one pound of ice 80 thermal units. This 
 gives a standard for comparison, as some substances will 
 take more thermal units than others to melt the ice. 
 
 By mixtures. A known weight of the substance whose 
 specific heat is required is heated to a certain temperature 
 and then immersed in water whose quantity and tempera- 
 ture are known. From the temperature of the water 
 after mixing, the specific heat is determined. 
 
 For example: If a pound of mercury at 132° F. be 
 poured into a pound of water at*32'', the temperature will 
 
 28 
 
Heat. 
 
 29 
 
 be 35.25° — that is, the water is heated 3.25° and the mer- 
 cury is cooled 96.75°. Then 96.75 : 3.25 : : i : (0.033) the 
 specific heat of mercury, — i representing the specific heat 
 of water. 
 
 The cooling method is based upon the fact that bodies 
 of different specific heat will occupy different lengths of 
 time in cooling through the same number of degrees. 
 Those that have the greatest specific heat will take the 
 longest to cool. Water and fluids in general have greater 
 specific heat than metals. 
 
 The specific heat of water is taken as unity. 
 
 The specific heat of substances increases with the tem- 
 perature, and especially as they near their fusing point or 
 change of state. 
 
CHAPTER XIII. 
 SOURCES OF HEAT AND COLD. 
 
 Sources of heat : 
 
 1 . Mechanical. 
 Compression. 
 
 , Friction. 
 Percussion. 
 
 Heat due to percussion is not the result of compression, 
 but to a vibratory motion given to the molecules. 
 
 2. Physical. 
 
 a. Solar radiation. 
 
 b. Terrestrial heat. 
 
 c. Electricity. 
 
 d. Change of state. 
 
 At a certain depth below the surface of the earth there 
 is a constant temperature ; below this the temperature in- 
 creases on the average of i° C. for every ninety feet of 
 descent. 
 
 3 . Chemical. 
 
 a. Combustion. 
 
 b. Animal heat. 
 
 c. Vegetable heat. 
 
 The heat of combustion depends upon the quantity, 
 while- the temperature upon the rapidity, of the combus- 
 tion. ' 
 
 Vegetable heat is more marked in plants at the time of 
 blossoming when oxidation accompanies the process. 
 
 30 
 
Heat. 31 
 
 ' The process of vegetation in general is not accompanied >. 
 by heat, for it is not an oxidation. 
 
 Under the influence of the sun's rays the green parts of 
 the plant decomposes the carbonic acid in the atmosphere 
 into oxygen and carbon which unite with the elements of 
 water to form cellulose, sugar, starch, etc. To effect this, 
 heat is required which is stored up in the plant and reap- 
 pears during combustion of wood, coal, etc., arising from 
 its decomposition. 
 
 SOURCES OF COLD. 
 
 a. Change of state. 
 
 b. Expansion of gases. 
 
 c. Radiation. 
 Especially nocturnal radiation. 
 
CHAPTER XIV. 
 MECHANICAL EQUIVALENT OF HEAT. 
 
 Heat is the result of motion, and it is found in all cases 
 in which motion is the direct producer of heat, that me- 
 chanical force is consumed. 
 
 By numerous experiments it has been found that the 
 mechanical equivalent of heat is 772 foot-pounds Fahren- 
 heit scale, or 1390 foot pounds Centigrade scale. 
 
 In other words, heat and mechanical energy are converti- 
 ble, and heat requires for its production, and produces by 
 its disappearance, mechanical energy in the ratio of 772 
 foot-pounds for every thermal unit. 
 
 WORK OF ENGINES. 
 
 Multiply together the mean pressure on the piston, the 
 area of the piston, and the length of stroke, the result will 
 equal the working power of the engine. 
 
 This work is compared \.o horse power, vi'a\c\i. represents 
 ^■i^o foot-pounds raised one foot per second. 
 
 A foot-pound is the work necessary to raise a pound a 
 foot high. 
 
LIGHT. 
 
 CHAPTER XV. 
 
 Theories : 
 
 1 . Emission theory. This theory assumes that all lu- 
 minous bodies emit an imponderable substance which, 
 penetrating-the eye, acts upon the retina, causing vision. 
 
 2. Uudulatory theory. This theory assumes that all 
 space and substances are filled with luminiferous ether, 
 and the luminosity of any body is due to the rapid vibra- 
 tory movement of its molecules, thus setting in motion 
 this ether, which in turn, acting upon the retina of the eye, 
 causes vision. 
 
 The undulatory theory is the one usually adopted. 
 
 PROPAGATION OF LIGHT. 
 
 Bodies may be : 
 
 Luminous. 
 
 Transparent. 
 
 Translucent. 
 
 Opaque. 
 
 a. Luminous bodies are those that admit light. 
 
 b. Transparent bodies, those that transmit light so ob- 
 jects can be distinguished through them. 
 
 c. Translucent bodies, those that transmit light im- 
 perfectly, so that objects are not distinguisl^able through 
 them. 
 
 33 
 
34 Physics. 
 
 d. Opaque bodies are those that do not transmit light. 
 Aluminous ray is the direction of the line in which light 
 is propagated. 
 
 A pencil of light is a collection of rays. 
 Rays of light may be : 
 
 a. Parallel. 
 
 b. Divergent. 
 
 c. Convergent. 
 
 A homogeneous medium is one whose chemical composi- 
 tion and density are the same in all parts. In homogene- 
 ous mediums, light is propagated in straight lines. 
 
 SHADOWS. 
 
 Shadow is the space behind an opaque body upon which 
 light is thrown. 
 
 Penumbra is the dark space around the true shadow of 
 an object, and is due to the light coming from a source 
 greater than a single point. 
 
 VELOCITY OF LIGHT. 
 
 The velocity of light has been obtained by means of as- 
 tronomical observations in noting the difference in time 
 of occultation of one of Jupiter's moons when the earth 
 is on opposite sides of its orbit. 
 
 This difference has been found to be i6' 36", which rep- 
 resents the time it takes light to travel across the earth's 
 orbit, and gives for its velocity nearly 190,000 miles a 
 second. 
 
CHAPTER- XVI. 
 INTENSITY OF LIGHT. 
 
 The following law governs the intensity of light : 
 
 The intensity of light is inversely as the square of its dis- 
 tance from the source of light. 
 
 Photometers are instruments for measuring the relative 
 intensities of light. 
 
 The sperm candle burning two grains per minute is 
 taken as the standard for this measurement. 
 
 Most photometers, as Rumford's and Bunsen's, are made 
 upon the principle that to obtain equal shadows light 
 must be of the same relative intensity. Therefore, by 
 placing the sources of light nearer or farther away from 
 the object casting the shadows, until they — the shadows — 
 are equal, the intensity of the light is determined by the 
 law that the intensity of light varies inversely as the 
 square of the distance. 
 
 Thus if one light is a foot away and a second light two 
 feet away from the object casting equal shadows, the light 
 two feet distant has four times the intensity of the one 
 only a foot away. 
 
 35 
 
CHAPTER XVII. 
 REFLECTION OF LIGHT. 
 
 The reflection of light is governed by the following 
 law : 
 
 The angle of reflection is equal io^^e^ng^e^^o^inpidencei 
 both rays being in the same plane and perpendicular to the 
 reflecting surface. ^ 
 
 By drawing a perpendicular to the reflecting surface at 
 the point where the rays meet it, the angle of incidence is 
 the angle these rays make with the perpendicular, while 
 the angle of reflection is the angle reflected rays make with 
 the perpendicular. 
 
 The intensity of the reflecting power of a body in- 
 creases with the degree of polish, and diminishes with the 
 obliquity of the incident ray. 
 
 REFLECTING SURFACES. 
 
 Mirrors are bodies with polished surfaces which show 
 by reflection objects presented to them. The image is the 
 place where the objects appear. 
 
 The surfaces of mirrors are : 
 
 Plane. 
 
 Curved. 
 
 I. Plane mirrors. In plane mirrors the image is formed 
 behind the mirror at a distance equal to that of the object 
 forming it, and on the perpendicular let fall from this object 
 
 36 
 
Light. 37 
 
 to the mirror. The image is erect, virtual, and equal in 
 size to the object forming it. 
 
 A virtual image is one formed by the prolongation of 
 the reflected rays, and not by these rays themselves. 
 
 A real image is one formed directly by the reflected 
 rays, and not by their prolongation. 
 
 Multiple images are formed by proper arrangement of 
 several mirrors, as for example in the kaleidoscope. 
 
 II. Curved mirrors. Curved mirrors may be : 
 
 Spheroidal. 
 
 Parabolic. 
 
 A. Spheroidal mirrors. The centre of curvature is the 
 centre of the sphere of which the mirror forms a part. 
 
 'Y^i^ principal axis is the line drawn from the centre of 
 curvature to the centre of the mirror. 
 
 The secondary axis is a line drawn from the centre of 
 curvature to any point on the mirror. 
 
 T\y& focus is the point at which the reflected rays meet. 
 
 The principal focus is the point where reflected parallel 
 rays meet. 
 
 The conjugate focus, the point where other than parallel 
 reflected rays meet. 
 
 Spheroidal mirrors are : 
 
 Concave. 
 
 Convex. 
 
 a. In concave mirrors which tend to converge all re- 
 flected rays, the principal focus is situated midway be- 
 tween the centre of curvature and the mirror. 
 
 The position of the image depends upon the relation of 
 the object to the mirror. 
 
 I. If the object is at such a distance that the rays 
 from it are parallel, the image will be situated at the prin- 
 cipal focus — real, smaller than the object, and inverted. 
 
38 Physics. 
 
 2. If the object is beyond the centre of curvature, the 
 image will be real, inverted, smaller than the object itself, 
 and situated between the centre of curvature and the 
 mirror. 
 
 3. If the object is between the centre of curvature and 
 the mirror, but nearer the centre of curvature, the image 
 will be real, inverted, larger than the object, and beyond 
 the centre of curvature. 
 
 4. If the object is between the centre of curvature 
 and mirror, but nearer the mirror, the image will be erect, 
 virtual, and larger than the object. 
 
 b. In convex mirrors, all reflected rays tend to diverge ; 
 whatever be the position of the object in relation to the 
 mirror, the image is always virtual, erect, and smaller than 
 the object itself. 
 
 B. Parabolic mirrors. 
 
 In parabolic mirrors, when the light is placed at the 
 principal focus, the reflected rays are nearer parallel than 
 they are in the simple concave mirrors. The light thus 
 reflected maintains its intensity for a greater distance, for 
 it is the divergence of the rays that diminishes the inten- 
 sity of light. 
 
 Parabolic mirrors are used as head-lights in engines, for 
 lantern reflectors, etc., on account of the reflected rays 
 being parallel, and hence maintaining their intensity. 
 
 SPHERICAL ABERRATION. 
 
 When concave mirrors are large the rays that are re- 
 flected from near the edges meet the axis of the mirror 
 nearer the mirror than those that are reflected from the 
 central portions. As a result, the image is not precise, or 
 there is spherical aberration by reflection. 
 
CHAPTER XVIII. 
 REFRACTION. 
 
 Refraction of light is the bending of the ray of light in 
 passing from one medium to another. 
 
 In passing from a denser to a rarer medium the ray is 
 bent from a perpendicular drawn to the surface of the 
 medium at the point of emergence, but toward the per- 
 pendicular in passing from a rarer to a denser medium. 
 
 There is in refracted light an angle of incidence and re- 
 fraction. 
 
 If a perpendicular be drawn to the surface separating 
 the two media at the point where the rays enter it, the 
 angle of incidence is the angle made by the ray and the 
 perpendicular ; and the angle of refraction is the angle 
 make by the prolongation of the perpendicular and the 
 bent ray as it passes through the second medium. 
 I The incident and refracted rays are in the same plane ' 
 I and perpendicular to the surface separating the two i 
 * media. 
 
 Most substances only refract the incident ray once, but 
 some crystalline bodies cause double refraction. 
 
 The index of refraction is the ratio between the sines 
 of the incident and refracted angles. 
 
 To find the angle of refraction of any substance, divide 
 the sine of the angle of the incident ray by the index of 
 refraction, and the result will be the sine of the refracting 
 angle. 
 
 39 
 
40 Physics. 
 
 For example. In the diamond say the angle of inci- 
 dence is 45° ; its sine would be .70711. The index of re- 
 fraction is 2.75. Thus, .70711 -^ 2.75 = .257, the sine 
 of the angle of refraction which corresponds to an 
 angle 15". 
 
 When a luminous ray passes from a greater to a less 
 refracting medium, at a certain obliquity of the ray the 
 angle of incidence is so great that the refracted ray 
 emerges parallel to the separating surface, and the critical 
 angle is the angle this oblique ray makes with the perpen- 
 dicular. Any greater obliquity of the incident ray will 
 Y cause total refraction and none of the rays will pass out of 
 the first medium. 
 
 MIRAGE. 
 
 Mirage is an optical illusion by which inverted images 
 are seen as if below ground or in the atmosphere. It is a 
 phenomenon of refraction and due to the unequal density 
 of different layers of air when they expand by contact 
 with the heated soil — the least dense rays being the 
 lowest. 
 
CHAPTER XIX. 
 TRANSMISSION OF LIGHT. 
 
 Light may be transmitted through : 
 Media with parallel faces. 
 Prisms. 
 Lenses. 
 
 1. When light is transmitted through media with 
 parallel faces the emergent rays are parallel to the inci- 
 dent rays. 
 
 2. K prism is any transparent medium between faces 
 inclined to each other. Any ray of light passing through 
 a prism is refracted twice in the same direction, once in 
 passing into the prism and then again on emergence. 
 
 The angle of deviation is the angle this emergent ray 
 makes with the incident. 
 
 3. Lenses may be considered as made of a number of 
 prisms. Lenses are named from their shape : 
 
 Convex. 
 Plano-convex. 
 Concave. 
 Plano-concave. 
 Diverging concavo-convex. 
 Converging concavo-convex. 
 The curved surfaces of lenses are arcs of circles. 
 The focus of a lens is the place the refracted rays 
 meet. 
 
 41 
 
42 Physics. 
 
 The real focus is that formed on the opposite side of the 
 lens from the luminous rays. 
 
 The virtual focus is that formed at the same side of the 
 lens as the luminous rays. 
 
 In convex lenses the principal focus, or the point where 
 parallel rays meet, corresponds nearly to the centres of 
 curvature of the lens. Convex lenses tend to converge all 
 luminous rays passed through them. 
 
 The position of the image depends upon the distance 
 away the object is from the lens. 
 
 a. If the object is at such a distance that the rays pro- 
 ceeding from it are parallel, the image will be real, in- 
 verted, smaller than the object, and situated at the 
 centre of curvature of the lens. / 
 
 b. If the object is beyond the centre of curvature, the 
 image will be real, inverted, smaller than the object, and 
 situated a little beyond the principal focus. 
 
 c. If the object is just beyond the centre of curvature, 
 the image will be real, inverted, larger than the object, 
 and situated some distance beyond the principal focus. 
 
 d. If the object is between the centre of curvature 
 and the lens, the image will be virtual, erect, larger than 
 the object, and situated beyond the principal focus. 
 
 Concave lenses. All rays passing through concave 
 lenses tend to diverge ; hence the image is always erect, 
 virtual, and smaller than the object. 
 
 SPHERICAL ABERRATION IN LENSES. 
 
 When the lens is large, the rays which are transmitted 
 near the edge reach a focus nearer the lens than those 
 rays which pass through near the axis, consequently the 
 image is indistinct, or there is spherical aberration by 
 refraction. 
 
CHAPTER XX. 
 
 DISPERSION AND ACHROMATION OF LIGHT. 
 
 When white light, or that which reaches us from the 
 sun, passes from one medium into another, it is decom- 
 posed into several kinds of light. This decomposi- 
 tion is called dispersion of light. 
 
 Thus if a pencil of solar light pass through a prism, and 
 be thrown upon a screen, seven principal colors are pic- 
 tured there, which are, from above downward, violet, 
 indigo, blue, green, yellow, orange, and red. These colors 
 thus produced are called the solar spectrum. The violet 
 is the most refrangible color, and the red the least. 
 
 The spectra formed by artificial light seldom contain all 
 the colors of the solar spectrum, but those present are in- 
 variably in the same order as those composing that spec- 
 trum. The colors of the spectrum are simple — that is, 
 they cannot be further decomposed. If, however, the 
 various colors are recombined, the result is white light 
 again. 
 
 The color of bodies depends upon the fact that one por- 
 tion of the colored rays contained in white light is ab- 
 sorbed, while the other portion is reflected, giving them 
 their color. 
 
 The bodies that reflect all the colors are white, while 
 those that reflect none are black ; mixed colors are those 
 produced by a combination of two or more colors. 
 
 Complementary colors are those which, when combined, 
 
 43 
 
44 Physics. 
 
 produce white. Homogeneous light is light containing but 
 one color, or monochromatic light. 
 
 Common salt burnt in Bunsen's lamp gives nearly a 
 homogeneous light. 
 
 PROPERTIES OF THE SPECTRUM. 
 
 a. Luminous properties. Light in the yellow portion of 
 the spectrum has the greatest, and in the violet the least 
 intensity. 
 
 b. Heating properties. The hottest portion of the 
 spectrum is just beyond the red, but depends somewhat 
 upon the kind of prism used to effect the dispersion. 
 
 c. Chemical properties are more marked just beyond 
 the blue portion of the spectrum. 
 
 DARK LINES IN THE SPECTRUM. 
 
 The color of the solar spectrum is not continuous, but 
 for several grades of refrangibility rays are wanting, and, 
 in consequence, it contains many dark lines. These lines 
 are always in the same position. 
 
 In spectra of artificial lights and stars the positions of 
 the dark lines are changed or replaced by bright ones, 
 when compared with the solar spectrum. 
 
 Fraunhofer s lines is the name given to the most marked 
 dark lines in the solar spectrum, and are designated by 
 letters of the alphabet. 
 
 Incandescent vapors have the power, of absorbing rays of 
 the same refrangibility as they UDi/mtf, and it is this prop- 
 erty of incandescent gases that explains the dark lines in 
 the solar spectrum and leads us to believe that the sun is 
 surrounded by incandescent gases which absorb the rays 
 produced by the luminous properties of the same incan- 
 descent substance in the sun. 
 
Light. 45 
 
 SPECTRUM ANALYSIS. 
 
 A very delicate means of detecting some of the in- 
 gredients in unknown substances is afforded by volatiliz- 
 ing a portion of the substance in a flame and denoting 
 the color it imparts to certain of Fraunhofer's lines. 
 
 This method of examination is called spectrum analysis. 
 It has been ascertained that whenever salts of the same 
 metal are introduced into a flame they always produce 
 lines identical in color and position. 
 
 Therefore by comparing the spectrum of any given sub- 
 stance with the solar spectrum, and noting which of 
 Fraunhofer's lines are replaced by bright lines, a delicate 
 means of analysis is afforded. For example, sodium 
 always give a bright yellow line in the exact position of 
 Fraunhofer's line D. with part of the spectrum absent. 
 
 The spectroscope is an instrument used for the study of 
 the spectrum, and in its simplest form consists of two tel- 
 escopes mounted on a common footing and a prism for 
 forming the spectrum. One telescope collects the rays of 
 light from the burning substance and throws them on the 
 prism, while the other is used to magnify the spectrum 
 produced. When three telescopes are used the spectra 
 are formed by burning the substance to be examined in 
 front of one of the telescopes by means of a Bunsen 
 burner, which gives but little light of its own and thus 
 does not obscure the lines in the spectrum to be pro- 
 duced, and some of the suspected substances in front of 
 another. 
 
 The spectra thus formed are brought by means of a 
 prism so they may both be seen by looking through the 
 third telescope and a comparison made by noting the 
 position of their bright lines. For example, if sodium is 
 suspected of being present in a given substance, burn a 
 
46 Physics. 
 
 portion of it in a Bunsen flame in front of one of the tel- 
 escopes, and a little sodium in front of the other, and if 
 the bright lines of the two agree, the supposed substance 
 is present. The spectroscope is also used in detecting 
 certain fluids, as blood and bile. / 
 
 This is done by placing some of the fluid between the 
 source of light and the spectroscope. The spectrum thus 
 produced has characteristic dark bands depending onj the 
 kind of fluid. 
 
 KINDS OF SPECTBIA. 
 
 Continuous. 
 
 Discontinuous, or bright-lined. , 
 
 Absorption, or dark-lined. 
 
 Positive, or bright-banded. 
 
 Negative, or dark-banded. 
 
 a. Continuous spectra are those formed by ignited fluids 
 and solids. 
 
 b. Discontinuous spectra are those produced by ignited 
 gases and elements. 
 
 c. Absorption spectra are those produced by the fixed 
 stars and the sun. 
 
 d. Positive or bright-banded spectra are those produced 
 by comets. 
 
 e. Negative or dark-banded spectra are those produced 
 by blood, bile, chlorophyl, and other liquids. 
 
 FLUORESCENCE. 
 
 Fluorescence is that property some substances have of 
 appearing colored when viewecf by reflected light, but are 
 colorless when seen by transmitted light. 
 
 This property is due to the retardation of the wave 
 movement by the light being reflected and thus brought 
 within compass of the eye. 
 
Light. 47 
 
 Fluorescence is not limited to reflected light, but may 
 also be produced by transmitted light, due to a change in 
 the refrangibility of the rays by passing them through the 
 substance. Thus placing a quinine solution in the solar 
 spectrum the invisible ultra-violet rays become visible 
 owing to a diminution in the refrangibility of these rays. 
 
 •CHROMATIC ABERRATION. 
 
 Simple lenses when a certain distance from the eye 
 give colored images, due to the unequal refrangibility of 
 the different colors, or wchromatic aberration. To correct 
 this, achromatic lenses, or lenses preventing decomposition 
 of light, are used, and made by combining lenses of differ- 
 ent substances, such as crown and flint glass. 
 
CHAPTER XXI. 
 
 OPTICAL INSTRUMENTS. 
 
 Among the most important optical instruments are the : 
 
 Microscope. 
 
 Telescope. 
 
 Magic-lantern. 
 
 Camera-obscura. 
 
 a. The simple microscope consists of a single convex lens 
 of short focal length, the object being placed between the 
 lens and its principal focus. Asa result there is produced 
 an erect, magnified, and virtual image. The compound 
 microscope in its simplest form consists of two convex 
 lenses. The one nearer the object is called the object-glass 
 or objective, and has a short focus ; the other is called the 
 eyepiece or power, and has a longer focus or is less con- 
 densing. 
 
 The object has to be placed very near the objective, 
 just beyond its principal focus. This forms a real, magni- 
 fied, and inverted image, which in turn is magnified by the 
 eye-piece, as is the object in the simple microscope. 
 
 To bring more of the rays into the field of vision, a 
 third convex lens, called the " Field lens," is sometimes 
 employed and placed between the objective and its image, 
 thus bringing the rays nearer together. 
 
 b. Telescopes. In astronomical telescopes there are object- 
 glasses and eye-pieces. The object is beyond the princi- 
 pal focus of the objective, hence a smaller, inverted, and 
 
 48 
 
Light. 49 
 
 real image is formed, which is magnified by the eye-piece, 
 as in the compound microscope. 
 
 The terrestrial telescope differs from the astronomical in 
 producing images in their proper positions. This is 
 effected by means of two convex lenses placed between 
 the objective and the eye-piece, so that the image when 
 magnified by the eye-piece will appear erect. 
 
 In Galileo's telescope, on the principle of which opera 
 glasses are constructed, the eye-piece consists of a double 
 concave lens, which gives at once an erect image, and in 
 this way differs from the astronomical telescope. The 
 eye-piece is so placed that the image formed by the ob- 
 jective would fall behind it, if it were not that the rays in 
 passing through the eye-piece are refracted and diverge, so 
 that the eye which receives them sees the image near by, 
 magnified, and erect. 
 
 c. Magic-lantern. This is an instrument for throwing 
 magnified images upon a screen. The reflected rays of a 
 lamp are made to fall upon a convex lens, which concen- 
 trates them upon the object to be magnified. 
 
 A double convex lens is then placed at a little more than 
 the principal focal distance from the object, and con- 
 sequently 2. real, magnified, and inverted image is produced 
 on the screen. 
 
 d. Camera-obscura, consists of a dark chamber with a 
 small aperture to admit the light. 
 
 The rays proceed from external objects through this 
 opening, and form small inverted images of these objects 
 on the opposite wall. The images are made much 
 brighter and clearer by placing a double convex lens in 
 the aperture. Photographs are taken by the camera. 
 
CHAPTER XXII. 
 
 PHOTOGRAPHY. 
 
 Photography is the art of fixing images of the camera- 
 obscura on substances sensitive to light. 
 
 The first real important step taken in photography was 
 by Daguerre in 1839, and in honor to him the pictures 
 thus taken are called daguerreotypes. A well-polished cop- 
 per plate is made sensitive by exposing it to bromine and 
 iodine vapors, which form iodide and bromide of silver. 
 This plate is then placed in the camera at the point where 
 the image will be formed, and allowed to remain a few 
 minutes thus exposed to the rays of light. 
 
 The plate is next exposed to the action of mercurial 
 vapor, which deposits metallic mercury only on the parts 
 affected by the light. All other portions of the iodide 
 and bromide of silver are removed from the plate by a 
 solution of hyposulphite of soda, which does not affect the 
 mercury. The plate is then washed with a solution of 
 the chloride of gold, which combines with the mercury 
 and increases the lustre of the picture. 
 
 Photographs are now taken on glass and then transferred 
 to paper. The glass plate is first coated with collodion 
 impregnated with iodide of potash. This plate is then 
 immersed in a solution of nitrate of silver, thus forming 
 on the plate iodide of silver, which is very sensitive to 
 light. The plate is next exposed to the light in the cam- 
 era, as in taking the daguerreotypes. 
 
 50 
 
Light. 5 1 
 
 A developer or solution of protosulphate of iron is then 
 poured over the plate, which reduces to the metallic state 
 those parts of the iodide of silver acted upon by the light. 
 The rest of the iodide of silver is washed off the sensitive 
 plate with hypo^dsphite of soda. 
 
 The image thus produced is called the negative. The 
 positive picture is obtained by impregnating paper with 
 the chloride of silver, placing over it the negative, and ex- 
 posing it then to the direct action of the sunlight for some 
 time. That portion of the chloride of silver on the paper 
 not acted upon by the light is then removed by a solution 
 of hyposulphite of soda. The light portions of the 
 negative are replaced by shades in the positive, thus 
 making the pictures to a certain extent more natural — 
 taking white, white ; and black, black. 
 
 Gelatine plates are frequently used instead of glass ; 
 the process of taking the picture, however, is essentially 
 the same. 
 
 Pictures produced by direct action of light : 
 
 Daguerreotype. 
 
 Talbotype — negative and positive prints. 
 Wax-paper process — Dr. Gray. • 
 
 Albumen on glass. 
 Wet collodion process. 
 Ambrotypes. 
 
 r Silver. 
 Prussian blue. 
 Platinum. 
 Uranium. 
 Gelatin. 
 Glass positives. 
 Dry plates — Honey — Tannin. 
 
 Paper prints- 
 
52 52 Physics. 
 
 7. Collodion emulsion. 
 
 8. Gelatine emulsion. 
 
 II. Photo-mechanical process : 
 I. Woodbury types. 
 
 Albertypes. 
 
 2. Collotypes 
 
 Artotypes. 
 
 Heliotypes. 
 
 Indotints. 
 
 „ , . ^ ( Photo-lithographs. 
 
 Gelatme transfers i th ^ 1 ^ ^ 
 
 ( Photo-electrotypes. 
 
 •D 1- f ( Photo-electrotypes. 
 
 Relief process ■< _,, . ■' ^ 
 
 ( Photo-engravmgs. 
 
 T . 1- (Photo-etching. 
 
 Intaglio process \ ° 
 
 t Photo-electrotypes. 
 
CHAPTER XXIII. 
 
 DOUBLE REFRACTION. 
 
 Some crystals, as Iceland spar, have the property of 
 splitting up the ray of light which passes through therri 
 into two parts, so that when any object is seen through 
 one of these crystals it appears double. 
 
 This property is explained by assuming that ether in 
 double refracting bodies is not equally elastic in all direc- 
 tions, so that the vibrations at right angles to each other 
 are transmitted with unequal velocities. One of the rays 
 into which the incident ray is divided is called the ordi- 
 nary, as it represents the ordinarily refracted ray ; and the 
 other the extraordinary ray, as it differs from commonly 
 transmitted light. 
 
 The images formed by double refraction are called the 
 ordinary and extraordinary, from the rays that produce 
 them. 
 
 The ordinary rays and images correspond to those of 
 single refraction. 
 
 INTERFERENCE OF LIGHT. 
 
 When two luminous rays from different sources meet at 
 acute angles, the mutual action produced is called inter- 
 ference of light, and as a result well-marked colors and 
 bands are formed which depend wholly upon the meeting 
 of these rays. 
 
 Interference of light or diffraction takes place when 
 
 53 
 
54 Physics. 
 
 light traverses the edge of a body, or through a small 
 aperture. It is also produced when light is reflected from 
 finely striated surfaces, as the mother of pearl, or from thin 
 transparent laminje, as glass, ice, soap bubbles, etc. New- 
 tons rings are examples of interference of light, and can 
 be seen by either transmitted or reflected light. They 
 are produced by a thin layer of air interposed between 
 two glasses tightly compressed. 
 
 This phenomenon produced by the interference of 
 light is due to the meeting of the waves of luminiferous 
 ether, and, coming from different sources, either weaken 
 or strengthen each other. As the waves of luminiferous 
 ether have different lengths and velocities for each color, 
 this interference of two rays consequently causes a differ- 
 ent display of colors than would have been produced by 
 either. 
 
 The red rays have the longest and the violet the short- 
 est wave-lengths. 
 
 POLARIZATION OF LIGHT. 
 
 Light, besides undergoing double refraction, is some- 
 times polarized — that is, made to vibrate in one plane 
 only. 
 
 Thus if a ray of light which has undergone ordinary 
 refraction be allowed to pass through a second crystal, it 
 may be divided into ordinary and extraordinary rays with, 
 unequal intensities, so that rotating the second crystal 
 will cause one ray to disappear entirely and the other to 
 be increased in brightness. The same is true with the ray 
 which has undergone extraordinary refraction, if made to 
 pass through the second crystal. 
 
 When light is polarized, the ordinary and extraordinary 
 rays are polarized in planes at right angles to each other. 
 
Light. 55 
 
 MEANS OF POLARIZING LIGHT. 
 
 Light may be polarized by: 
 Reflection. 
 Single refraction. 
 Double refraction. 
 
 a. By reflection. The instrument used for polarizing 
 light by reflection is called a. polariscope. It consists of a 
 hollow tube with a plate of dark glass at each end, so ar- 
 ranged as to be able to revolve about each other, and to 
 assume any angle. If light strike the first reflecting sur- 
 face at an angle of 35° 25', called th& polarizing angle, the 
 reflected light becomes polarized — that is, vibrates in one 
 plane only. If the surface of the second glass is parallel 
 to that of the first, the polarized ray will be reflected, but 
 if at right angles to it no light will be reflected. All re- 
 flected surfaces have a polarizing angle — that for water 
 being 52° 45'. 
 
 b. By single refraction. When a luminous ray falls 
 upon a glass plate at the polarizing angle, part of it is 
 reflected and part refracted. That which is refracted is 
 found to be partially polarized also, and if made to pass 
 through several such plates placed parallel, the refracted 
 ray will be found completely polarized. 
 
 c. Double refraction. By this means of polarizing light, 
 two prisms are needed. One is called an analyzer, for by 
 means of rotating it the ordinary and extraordinary rays 
 are made to appear and disappear, thus indicating that 
 the light is polarized ; and the other the polarizer, by 
 means of which the light is polarized. 
 
 The best prisms used for polarization are made of tour- 
 maline, which has the property of absorbing the ordinary 
 ray, and Iceland spar, which also, as in Nicol's prism, has 
 the property of transmitting only one beam of the polar- 
 ized light. 
 
56 Physics. 
 
 INTERFERENCE OF POLARIZED LIGHT. 
 
 When rays of polarized light meet, they cause inter- 
 ference, as do the rays of ordinary refracted light, and as 
 a result are produced fringes of light with various colors, 
 these colors depending upon the planes of polarization. 
 
 This phenomenon is best produced by transmitting the 
 polarized ray through lamina of double refracting cr>'stals, 
 compressed glass, etc. By rotating these crystals beauti- 
 ful colored rings are produced. 
 
 ROTATORY POWER OF LIQUIDS. 
 
 A great many liquids, as saccharine solutions, possess 
 the power of rotating the plane of polarized light either 
 toward the right or the left, and by noting the direction 
 and the number of degrees this plane is rotated from its 
 original position, the composition of different substances 
 may be detected when chemical analysis fails. 
 
 This rotatory polarization is determined by passing the 
 polarized light through the liquid when the analyzer is so 
 placed that no light is transmitted. The polarized beam 
 will now pass through the analyzer, and by turning it to 
 the right or left until no light is transmitted, will give the 
 number of degrees of the liquid's rotatory power. 
 
 Soleil's saccharimeter is an apparatus, the principle of 
 which is based on the rotatory power of saccharine solu- 
 tions. 
 
 By noting the number of degrees any given saccharine 
 solution causes the plane of polarized light to rotate, the 
 amount of sugar can be approximately obtained. 
 
CHAPTER XXIV. 
 SOURCES OF LIGHT. 
 
 l^ight is furnished us by : 
 
 a. Heavenly bodies. 
 
 b. Chemical combustion. 
 
 c. Electricity. 
 
 d. Phosphorescence. 
 
 Phosphorescent substances are those that after exposure 
 to certain conditions will shine in the dark. This phe- 
 nomenon may be referred to the following causes : 
 
 a. Spontaneous phosphorescence, or that seen in vege- 
 tables and animals. 
 
 b. Elevation of temperature. 
 
 c. Mechanical effect. 
 
 d. Electricity. 
 
 e. Exposure to the sun's rays. 
 
 The sulphate of calcium and strontium are two such 
 substances, and will shine in the dark for many hours 
 after exposure to strong light. 
 
 57 
 
ELECTRICITY AND MAGNETISM. 
 
 CHAPTER XXV. 
 
 MAGNETISM. 
 
 Magnets are bodies that attract iron, and the force ex- 
 erted is called magnetism. 
 
 Theory of fnagnetism : 
 
 In all bodies, two magnetic fluids, called positive and 
 negative, are circulating in opposite directions among the 
 molecules. In most substances these fluids neutralize 
 each other, but in magnets the positive fluid collects at 
 one end of each molecule and the negative at the other 
 end. 
 
 KINDS OF MAGNETS. 
 
 Magnets are either : 
 
 Natural. 
 
 Artificial. 
 
 a. A natural magnet, or loadstone, is an oxide of iron — • 
 FeeO^. 
 
 b. Artificial magnets ■m&y he : 
 
 1. Temporary. 
 
 2. Permanent. 
 
 Temporary magnets are made of iron, which assumes 
 the property of magnets by passing an electric current 
 around the iron {see chapter on electro-magnets), or by 
 magnetic induction. 
 
 58 
 
Electricity and Magnetism. 5g 
 
 After the exciting cause is removed the iron loses its 
 magnetic properties. 
 
 Permanent magnets are made of steel, which assumes 
 the magnetic property by passing a - strong current of 
 electricity around the steel, or by rubbing the steel with 
 a magnet for some time. 
 
 After the exciting cause is removed the steel retains its 
 magnetism. 
 
 PROPERTIES OF MAGNETS. 
 
 Magnets have the following properties : 
 
 Attracting iron. 
 
 Assuming a given direction. 
 
 Declination. 
 
 Inclination, or dip. 
 
 Magnetic induction. 
 
 Magnetic rupture. 
 
 a. The attracting force of a magnet is more marked 
 the nearer the ends are approached, and diminishes tow- 
 ard the centre, at which point it is absent. 
 
 The poles of a magnet are near the ends, where the 
 attracting force is the greatest. 
 
 The neutral point is at the centre of the magnet, where 
 the attracting power is nothing. 
 
 b. A magnet or magnetic needle, when freely suspended, 
 assumes a given direction, with its poles always pointing in 
 the same direction. The pole pointing toward the north 
 is called the north pole, while the one toward the south is 
 called the south pole. 
 
 Poles of the same name repel each other, while those of 
 opposite name attract each other. 
 
 An astatic needle is one not influenced by the earth's 
 magnetism, and is usually a combination of two needles, 
 with poles in contrary directions. 
 
&0 Physics. 
 
 c. Declination of magnetic needle. The north and 
 south poles do not point geographically north and south. 
 The amount of declination, however, is not constant, but 
 differs in places and from time to time. 
 
 d. Inclination or dip of the magnetic needle is its ten- 
 dency, when freely suspended, to incline from the hori- 
 zontal plane. North of the equator the north pole dips 
 as the geographical pole is approached, until, before that 
 point is reached, the needle becomes vertical in direction. 
 
 The same is true of the south pole south of the equa- 
 tor. Those points where the needle assumes the perpen- 
 dicular are called the magnetic poles of the earth. 
 
 e. Magnetic induction is that property which magnets 
 have of temporarily making magnets of iron when brought 
 directly or nearly in contact with the iron. Such a tem- 
 porary magnet has in turn, but to a lesser extent, power 
 of induction on other iron. 
 
 As soon as the influence of the permanent magnet is 
 taken away, the iron loses its magnetic properties. 
 
 f. Rupture of magnets. When a magnet is broken 
 into a number of pieces, every portion will become imme- 
 diately a complete magnet in itself. 
 
CHAPTER XXVI. 
 ELECTRICITY. 
 
 Electricity is a physical agent manifesting itself by- 
 attraction, repulsion, heat, light, etc. ; not inherent in 
 bodies, but evoked by a variety of causes, as friction, 
 chemical action ; and the electrical condition of such a 
 body is called potential. 
 
 Theories : 
 
 1. FranklirCs theory. All substances contain an im- 
 ponderable fluid in a quiet state, but when excited, as by 
 friction, a portion of this fluid is drawn off, leaving a pre- 
 ponderance of the other portion, which causes the phe- 
 nomena of electricity. 
 
 2. Timmer's theory. All substances contain two fluids 
 which ordinarily neutralize each other, but when excited 
 are separated and cause the manifestations of electricity. 
 
 Admitting this fluid theory of electricity, any body may 
 be charged with an excess of either one fluid or the other, 
 which are called positive and negative fluids, and from 
 which we have the following law: Two bodies charged 
 with the same electricities repel each other, but with opposite 
 electricities attract each other. 
 
 CONDUCTORS AND NON-CONDUCTORS. 
 Bodies in which electricity passes rapidly from one part 
 to another are cdXled good conductors ; but those bodies in 
 which it does not, are called poor conductors or non-con- 
 ductors. Glass is the best non-conductor. Poor conductors 
 are also called insulators. 
 
 6i 
 
CHAPTER XXVII. 
 KINDS OF ELECTRICITY. 
 
 There are two principal kinds of electricity : 
 
 1. Statical. 
 
 2. Dynamical. 
 
 STATICAL ELECTRICITY. 
 
 Statical or frictional electricity was the first kind of 
 electricity discovered, and is produced by friction. 
 
 PROPERTIES OF STATICAL ELECTRICITY. 
 
 Statical electricity has the properties of : 
 Surface distribution. 
 Rapid dissipation. 
 Induction. 
 
 a. The distribution of electricity in any body charged 
 with statical electricity, is upon the surface, and has the 
 greatest intensity at the most acute points on that sur- 
 face. 
 
 b. Statical electricity is rapidly dissipated from bodies 
 even when they are properly insulated — that is, mounted 
 on non-conductors. 
 
 Electricity is dissipated by : 
 
 The air. 
 
 Imperfect insulation. 
 
 c. There is induction by statical electricity as there is 
 induction by magnets. Thus, when an insulated con- 
 
 68 
 
Electricity and Magnetism. 63 
 
 ductor is charged with electricity, any body in a neutral 
 state and insulated, placed near it, will be acted upon in a 
 manner analogous to that of a magnet upon soft iron. 
 
 In other words, it decomposes the neutral fluid in the 
 body, attracting the opposite and repelling' the like kind 
 of electricity. This body will in turn have a similar ac- 
 tion on other insulated bodies, but all will have their 
 electric fluids neutralized again by withdrawing the in- 
 fluence of the charged conductor. 
 
 The different kinds of electric fluid — negative and 
 positive — are collected at the extremities of these bodies 
 charged with induced electricity, while at the centre is a 
 space destitute of free electricity. 
 
CHAPTER XXVIII. 
 
 ELECTRICAL MACHINES. 
 
 Among the most important of statical electrical 
 tnachines are the : 
 
 ■ Electroscope. 
 
 ■ Glass plate machines. 
 Electrophorus. 
 Leyden jar. 
 
 a. The electroscope is an instrument used for detecting 
 the presence and kind of electricity in a body. 
 
 This consists essentially of an insulated metallic rod at 
 the end of which two gold leaves are attached. 
 
 If any electrified body is brought near the rod, the elec- 
 tric fluid will be decomposed by induction, and conse- 
 quently the gold leaves will be charged with one kind of 
 electricity, causing them to diverge, while the opposite 
 end of the rod will be charged with the other kind. 
 
 The presence of electricity is thus determined by the 
 divergence of the gold leaves, but not the kind. This is 
 determined as follows : While the rod is still charged by 
 induction from an electrified body, touch the end of the 
 rod. This will remove one kind of electricity and leave 
 the rod charged with the opposite or other kind. After 
 removing the finger take away thedKducing agent and 
 apply to the rod a positively electrified body, as an excited 
 brass rod. 
 
 If the gold leaves diverge more widely the former body 
 
 64 
 
Electricity and Magnetism. 65 
 
 was negatively charged, for like electricity will be repelled 
 to the opposite extremity. The reverse is true if the 
 gold leaves are less divergent. 
 
 b. Plate electrical machines are instruments used princi- 
 pally for storing up statical electricity. The usual form 
 of this machine consists of a circular plate of glass at the 
 upper and lower parts of which are two cushions which 
 act as rubbers when the plate is turned. In front of the 
 plate are two insulated conductors terminating in 
 branches which are bent around the plate between the 
 rubbers and studded with points projecting toward the 
 glass. When the plate is turned or revolved it becomes 
 charged with positive electricity by friction against the 
 rubbers. To equalize this positive electricity on the glasis 
 plate, negative electricity is given off from the conductors 
 through the projecting points, thus leaving the conduc- 
 tors charged with positive electricity. 
 
 The cushions are connected with the earth by a me- 
 tallic chain so that the negative electricity from the plate 
 can escape to the ground. Holtz invented a machine by 
 which a body is electrified by friction once for all, and 
 made to act by induction in such a way as to produce a 
 continual generation of electricity by the rotation of a 
 glass plate. The electrophorus acts on the same principle. 
 
 c. The electrophorus consists of a disc of resin and a me- 
 tallic disc with an insulated handle. The resin is electrified 
 by friction and the metallic plate then placed upon it, 
 which in turn becomes charged with electricity by induc- 
 tion from the resin. If this plate still in position is touched 
 by the finger, the like kind of electricity passes to the 
 ground, while the plate remains charged with the opposite 
 kind. If now removed from the resinous disc by means 
 of the insulated handle, it still contains but one kind of 
 
66 Physics. 
 
 electricity, and by touching it a spark denotes the union 
 or the neutralizing of the two fluids. 
 
 This can be repeated a number of times without again 
 exciting electricity in the resin. 
 
 CONDENSATION OF ELECTRICITY. 
 
 A condenser is an apparatus for storing up a large quan- 
 tity of electricity on a small surface. 
 
 There are a great many forms of condensers, but the 
 Leydenjar is the most convenient. 
 
 d. The Leydenjar consists of a glass bottle, the interior 
 of which is coated with tin-foil, and the exterior of the 
 neck of the bottle with the same material. The neck of 
 the bottle is provided with a cork through which passes a 
 brass rod terminating externally in a knob and internally 
 by a chain communicating with the tin-foil. 
 
 The jar is charged by connecting the external surface 
 with the ground and the interior, by means of the brass 
 knob with the source of electricity. In this way the inner 
 surface of the jar becomes charged with one kind of elec- 
 tricity and the outer by the opposite kind, owing to the 
 law of attraction and repulsion of electrical fluids. 
 
 By connecting the outer with the inner coatings of the 
 jar, by means of a good conductor, the two fluids unite, or 
 the jar is discharged, as indicated by a spark. 
 
 It is found by experiment that nearly all the charge of 
 electricity resides on the inner and outer surfaces of the 
 glass and not on the tin-foil, the mutual attraction of the 
 two opposite electricities causing them to approach as 
 nearly as possible, their union being prevented by the 
 poor conductivity of the glass. 
 
 The extent of charge for a Leyden jar depends direct- 
 ly upon the extent of surface and inversely upon the 
 thickness of the insulator — glass. 
 
CHAPTER XXIX. 
 EFFECTS OF ELECTRICAL DISCHARGE. 
 
 The electric discharge is the phenomenon which accom- 
 panies the union of two opposite electric fluids, and may 
 be either continuous or sudden, the difference being one of 
 degree and not of kind. 
 
 The effects of the discharge may be either: 
 
 Physiological. 
 
 Luminous. 
 
 Heating. 
 
 Magnetic. 
 
 Mechanical. 
 
 Chemical. 
 
 a. The physiological effects consist in a violent exciting 
 action on the sensible and contracting elements of the 
 organic tissues through which electricity passes. 
 
 b. Luminous effects often accompany the recombination 
 of the two electrical fluids, and manifested by flashes or 
 sparks of light, the color depending upon the surrounding 
 medium. Its spectrum is full of dark lines. 
 
 c. Heating effects. The electric spark is the source of 
 intense heat. Gas can be ignited, alcohol set on fire, etc., 
 by the spark coming in contact with it. 
 
 d. Magnetic effects. By passing the discharge through 
 a coil of wire inside of which a steel needle is placed, the 
 needle will afterwards be found magnetic. 
 
 e. Mechanical effects consist in lacerations, fractures, etc., 
 
 67 
 
 < < 
 
68 Physics. 
 
 which follow a powerful discharge of electricity through a 
 poor conductor. 
 
 Lightning rods are placed on buildings to allow of the 
 harmless passage of electricity from the clouds to the 
 ground. They are best made of gas-pipe filled with pul- 
 verized charcoal ; the tips made of solid iron. The rods 
 should extend in the ground below moisture, and should 
 be connected both above and below ground. 
 
 f. Chemical effects result in decomposition and recom- 
 binations, produced by the passage of the electrical dis- 
 charge through substances. 
 
 Thus gases in proper proportions are made to combine, 
 by passing a spark through them. 
 
CHAPTER XXX. 
 
 DYNAMICAL ELECTRICITY. 
 
 The discovery of dynamical or current electricity is du^ 
 to Galvani, whose investigations on the influence of elec- 
 tricity on animals, especially the frog, led to additional 
 discoveries as to the nature of this form of electricity. 
 
 Volta attributed the contractions of the frog's legs in. 
 Galvani's experiments to the metal conductor used to ex- 
 cite these contractions, so he constructed the Voltaic pile „ 
 which consists of a series of discs of copper, zinc, and wet 
 cloth arranged in uniform order. 
 
 This experiment worked so well that it led to further 
 investigations, which resulted — as the general belief that 
 this form of electricity was due to chemical action — in the 
 construction of chemical batteries for the production of 
 electricity. 
 
 ELECTRICAL UNITS. 
 
 Before considering the construction of electric batteries 
 it is important to understand the units of measurement 
 used in electricity. 
 
 These are the : 
 
 Coulumb. 
 
 Ampere. 
 
 Volt. 
 
 Ohm. 
 
 Watt. 
 
 69 
 
70 Physics. 
 
 a. A coulumb or weber is the quantity of electricity that 
 passes in one second under a force of one volt and against 
 one ohm. 
 
 b. An ampere is the current produced by one volt 
 against one ohm, and will decompose .00142 of a grain of 
 water. 
 
 c. A volt is the force necessary to produce a current of 
 one ampere against one ohm. It about equals the force 
 produced by one Daniell cell (see kind of batteries). 
 
 d. An ohm is the resistance to the current electricity 
 necessary to allow of one ampire under a force of one 
 volt. It is equivalent to the resistance offered by a tele- 
 graph wire ^y diameter and 250 feet in length. 
 
 e. A watt is the power developed by one ampire falling 
 one volt, and is equal to y^^ of a horse-power. 
 
CHAPTER XXXI. 
 
 CHEMICAL BATTERIES. 
 
 In all batteries the metal acted upon is called the posi- 
 tive and the other the negative plate. 
 
 If these two plates are connected with a wire the direc- 
 tion of the current is determined by the positive metal — 
 I that is, the current always passes from the positive to the 
 'negative in the fluid, and from the negative toward the 
 positive out of the fluid. 
 
 By the direction of the current is always meant the 
 direction of the positive current, or the one above 
 described. The negative current always takes the oppo- 
 site direction, but for all practical purposes it is never 
 Iponsidered. 
 
 ; If the wire connecting the two plates be divided, the 
 electricity collects at the divided ends, hence these are 
 called the po/es or electrodes. 
 
 The positive electrode is always the one connected with 
 ! the negative plate, while the negative electrode is connected 
 with the positive plate. 
 
 KINDS OF BATTERIES. 
 
 Among the many batteries constructed the following 
 are the most important : 
 The simple battery. 
 Daniell's battery. 
 Grove's battery. 
 
 71 
 
72 Physics. 
 
 Bunsen's battery. 
 Gravity battery. 
 Grenet battery. 
 Leclanche battery. 
 
 a. The simple battery consists of a plate of copper and 
 one of zinc suspended in a weak solution of sulphuric 
 acid. The chemical action which results, causing the 
 production of electricity, is as follows : 
 
 Sulphuric acid. Zinc. Hydrogen. Zinc sulphate. 
 
 H,(S04) + Zn = H, + ZnCSO^). 
 
 The zinc is the positive and the copper the negative plate. 
 
 This form of battery is seldom used, for the current 
 rapidly diminishes until after a few hours it ceases to act 
 at all. 
 
 This diminution is due to the following causes: 
 
 1. Decrease of chemical action. 
 
 2. Local action. 
 
 3. Polarization of negative plate. Local action '\s the 
 production of small closed circuits of electricity in the 
 positive plate, due to impurities. 
 
 This can be prevented to a certain extent by amalga- 
 mating the zinc — that is, rubbing, it over with metallic 
 mercury. 
 
 Polarization is the formation of hydrogen gas on the 
 copper plate, thus interfering with the contact between the 
 fluid and the metal. The hydrogen also decomposes the* 
 zinc-sulphate, causing a deposit of metallic zinc on the 
 copper. 
 
 b. DanieWs battery. This consists of a glass vessel 
 filled with a solution of sulphate of copper, in which is 
 immersed a cylinder of copper and crystals of the sulphate 
 of copper. 
 
Electricity and Magnetism. 73 
 
 Inside the cylinder is a porous earthen cup containing a 
 weak solution of sulphuric acid, suspended in which is a 
 cylinder of zinc. The chemical action resulting is as 
 follows : 
 
 Sulphuric acid. Zinc. Zinc-Sulpliate. Hydrogen, 
 
 H,(SOJ + Zn = Zn(S04) + H^ 
 
 Hydrogen. Copper-Sulphate. Copper. Sulphuric acid, 
 
 H3 + Cu(S04) = Cu + H^CSO^.) 
 
 In this way the hydrogen decomposes the sulphate of 
 copper, thus preventing the polarizing of the copper plate, 
 and the sulphuric acid formed replenishes that which is 
 decomposed by its action on the zinc. The sulphate of 
 copper which is decomposed by the action of the hydro- 
 gen is replenished by the undissolved crystals. 
 
 c. Grove's battery. This consists of a glass vessel filled 
 with diluted sulphuric acid, immersed in which is a cylin- 
 der of zinc. 
 
 Within this cylinder is a porous earthen cup containing 
 nitric acid, suspended in which is a plate of platinum. 
 The following chemical action results : 
 
 zinc. Sulphuric acid. Zinc-sulphate. Hydrogen. 
 
 Zn -f H,(SO,) = Zn(SO,) + H, 
 
 Hydrogen. Nitric acid. Water. Nit. dioxide. 
 
 3H, + HNO3 = 4H2O + N,0, 
 
 The NgOg fumes pass off in the air. 
 • d. Bunsen's battery is the same as Grove's, except the 
 platinum is replaced by a carbon plate, the chemical action 
 being the same. 
 
 e. Tke chromic acid or Grenet batteries are like Bunsen's 
 and Grove's, except the nitric acid is replaced by a solu- 
 tion of bi-chromate of potash in sulphuric acid, thus 
 doing away with the disagreeable fumes. 
 
74 Physics, 
 
 Pot.-bi-chromate. Sulph. acid. Hydrogen. 
 
 KgCr^O, + 4H3S04 + 3H2 = 
 
 Pot. sulph. Chrom. sulph. Water. 
 
 K,SO, + Cr,(SO,)3 + 7 H3O 
 
 f. The gravity battery consists of a glass vessel in the 
 bottom of which is a copper plate covered with crystals of 
 sulphate of copper. The vessel is then filled with water 
 and a zinc cylinder immersed in it. The chemical action 
 is the same as seen in DanieWs battery. 
 
 The sulphate of sine which forms floats on the surface 
 of the sulphate of copper, owing to its lower specific 
 gravity, and the battery thus replenishes itself. 
 
 g. Leclanche battery consists of a carbon rod in a porous 
 cup containing a mixture of gas^ graphite, and peroxide 
 of manganese ; surrounding this porous cup is a zinc plate 
 immersed in a strong solution of sal-ammoniac which is 
 the exciting fluid. The electro-motor force is great, but as 
 the battery soon becomes polarized it is not adapted to 
 continuous work, but if left to itself will soon regain its 
 strength. 
 
 In all these forms of batteries, a single cell is called an 
 element, but a combination of cells a battery. 
 
 In combining the cells, the positive plate in one is con- 
 nected with the negative in another by means of a wire, 
 and so on from one element to another, until all the cells 
 are joined. Increase the number of elements and in this 
 way increase the strength of the current. 
 
 If on the contrary all the same kind of plates in the 
 elementsarejoined together, we increase the surface acted 
 upon, and in this way the quantity of electricity produced 
 is proportionally increased. 
 
 Change the size of the elements and the quantity of elec- 
 tricity is altered, but not its intensity. 
 
CHAPTER XXXII. 
 ATTACHMENTS TO A BATTERY. 
 
 The most important attachments to a battery are the — 
 
 Galvanometer. 
 
 Rheostat. 
 
 Current selector. 
 
 Communicator, 
 
 Rheophores. 
 
 Electrodes. 
 
 a. The Galvanometer is an apparatus by means of which 
 the direction and intensity of currents can be determined, 
 and is based upon the principles of deflection of the 
 needle by the current. 
 
 The direction and measurement of voltaic currents of 
 electricity are determined by the magnetic effects they 
 produce. 
 
 If a wire is suspended horizontally in the direction of 
 a magnet, and a current be passed through this wire, the 
 needle is deflected and tends to take a position which is 
 more nearly at right angles to the magnetic meridian in 
 proportion as the current is stronger. 
 
 If, however, instead of having a single wire, a complete 
 circuit is formed around the needle, or several such cir- 
 cuits are made, the effect is multiplied. 
 
 If the observer imagine himself the wire, the current 
 entering his feet and passing out of his head, and his face 
 always toward the needle, the north pole of the needle 
 will always be deflected toward the left of the current. 
 
 75 
 
76 Physics. 
 
 b. The rheostat is an appliance used to regulate the ex- 
 ternal resistance of a current. It is made of various sub- 
 stances, but the fluid rheostat is the best. It is so arranged 
 that the external current is made to pass through various 
 amounts of fluid, the amount interposed regulating the 
 strength of the current. 
 
 c. The current selector is an apparatus so arranged that 
 any given number of cells composing the battery can be 
 thrown in or excluded from the circuit. It is usually ar- 
 ranged in form of a switch on a key-board. 
 
 d. The communicator is an apparatus for changing the 
 poles of a battery without disturbing the rheophorcs and 
 is also usually arranged as a switch upon a key-board. 
 
 e. The rheophores are the wires transmitting the current 
 from the battery to the electrodes, and are usually made 
 of copper wire insulated with silk or cotton covering. 
 
 f. The electrodes are the termini of the rheophores, and 
 are made of various substances, as sponge, metal, wires, 
 etc. 
 
 The negative electrode is called the katrode, and the 
 positive the anode. 
 
CHAPTER XXXIII. 
 
 INTENSITY AND RESISTANCE OF THE ELECTRO-MOTOR 
 
 FORCE. 
 
 The electro-motor force is that force by which electri- 
 city is set in motion. It is the difference in potential of 
 the cell elements and is therefore unchanged by their size. 
 
 The difificulty which a current has in completing its 
 circuit is called the resistance, and may be either external 
 or internal. 
 
 a. External resistance is that offered to the passage of 
 the current between the negative and positive elements of 
 the cell, and is modified by the length, the diameter, and 
 character of the conductor employed. 
 
 b. The internal or fluid resistance is that offered to the 
 passage of the current between the positive and negative 
 elements of the cell, and may be modified by the distance 
 between, the character of the fluid between, the intervention 
 of some foreign body between, and by the size of, the ele- 
 ments. The larger the elements, the more direct the pas- 
 sage of the current, the better the conducting power of 
 the fluid, and the nearer the elements the less will be the 
 internal resistance. 
 
 The intensity and resistance of the electro-motor force 
 are governed by the following laws : 
 
 a. OhnHs law : The intensity of a current is equal to the 
 electro-motor force, divided by the resistance ; and is inversely 
 
 77 
 
78 Physics. 
 
 proportional to the length, and directly to the section, of the 
 conductor. 
 
 b. The resistance of current is inversely proportional to 
 the intensity of the current and section of the conductor, 
 and directly as the length of the conductor. 
 
CHAPTER XXXIV. 
 
 EFFECTS OF CURRENT ELECTRICITY. 
 
 The effects of current electricity may be : 
 
 Magnetic. 
 
 Heating. 
 
 Luminous. 
 
 Physiological. 
 
 Chemical. 
 
 a. The magnetic effects have already been considered. 
 
 b. Heating effects. The heat disengaged in any given 
 time is directly proportional to the square of the strength 
 of the current and to the resistance. 
 
 A battery of thirty Bunsen elements will melt copper 
 wire, hence the thermal effect of the current is used for 
 firing mines, cauterizing, etc. 
 
 The heating effects depend more upon the size of the 
 plates than upon the number of them when the resistance 
 is not great. 
 
 c. Luminous effects. In making and breaking a vol- 
 taic current at the point of contact a spark i? obtained. 
 If at the two terminals of a strong battery, pencils of car- 
 bon are placed near together, and an intense current 
 passed, the pencils become incandesent, and a luminous 
 arc extends between the two points called the voltaic arc. 
 
 The electric light has the same chemical properties as 
 solar light. Its spectrum has several bright lines. 
 
 79 
 
8o Physics. 
 
 In the incandescent-electric lamps, of which Edison's and 
 Maxum's are good examples, the luminous effects are pro- 
 duced by the intense heating of a carbon thread or plati- 
 num wire by passing an electric current through them in 
 a vacuum or a rarefied atmosphere of nitrogen or gaseous 
 hydrocarbons containing no oxygen. As it takes a current 
 of from 40 to 50 Bunsen elements to produce an electric 
 light equal to 500 candle power, it is found advisable to 
 obtain the required amount of electricity by means of the 
 magneto-electric machine. 
 
 d. Physiological effects. The voltaic current has the 
 property of causing contraction of all protoplasmatic 
 matter, and excitement throughout the nervous system. 
 These effects are only produced at the opening and closing 
 of the circuit. 
 
 e. Chemical effects. Many substances are decomposed 
 into their elements by the voltaic current. This decom- 
 position is called electrolysis. This positive electrodes 
 effecting the electrolysis is called the anode, and the 
 negative the kathode. 
 
 Many substances previously considered elements have 
 by electrolysis been proven to be of a compound nature. 
 In the decomposition of salts the acids are liberated at the 
 anode, and the bases at the kathode. Electrolysis cannot 
 take place in substances unless they are conductors. 
 
 ELECTRO-METALLURGY. 
 
 Electro-metallurgy or galvanoplastics, is the decomposi- 
 tion of salts by which certain metals are precipitated on 
 the negative plate. In this way electro-gilding is done. 
 
 A mould of the object to be reproduced by electro- 
 plating is first taken, and if not a good conductor is 
 made so by coating with graphite. It is then suspended in 
 a solution of the metal to be deposited and connected 
 
Electricity and Magnetism. 8i 
 
 with the negative pole of the battery, while a plate of 
 a similar metal is suspended in the fluid, and connected 
 with the positive pole. The electric current decom- 
 poses the fluid and deposits the metal on the mould (neg- 
 ative plate). 
 
CHAPTER XXXV. 
 
 ELECTRO-DYNAMICS. 
 
 Electro-dynamics treats of the laws of electricity in a 
 state of motion, or the action of electric currents on each 
 other and on magnets. Two currents parallel, and in the 
 same direction, attract each other, but in contrary directions, 
 repel each other. 
 
 Currents impart the same rotatory motion to magnets 
 that they do to currents, directing them at right angles to 
 the current ; but not only do currents act upon magnets, 
 but magnets also act upon currents, causing them to ro- 
 tate when the magnet is fixed. 
 
 The earth, which exercises a directive action on mag- 
 nets, acts also on currents. Thus every vertical current 
 tends to place itself under the earth's influence, in a plane 
 perpendicular to the earth's magnetic meridian, but every 
 horizontal current tends to have a continuous rotatory 
 movement rather than a directive one. 
 
 Not only has the earth a directive tendency on a freely 
 movable current, but also causes, as in the magnet, an in- 
 clination or dip of a circuit when it is properly balanced. 
 
 MAGNETIZATION BY CURRENTS. 
 
 Electro-magnets are bars of soft iron which under the in- 
 fluence of a voltaic current become magnets. But this 
 magnetism is only temporary, for so soon as the current 
 ceases the iron is no longer a magnet, or if at all, a very 
 
 82 
 
Electricity and Magnetism. 83 
 
 weak one, the magnetism remaining being called residual. 
 These electro-magnets are usually made in the horse-shoe 
 form, and the insulated copper wire is wound around the 
 two armatures in the same direction, so as to form 
 bobbins. 
 
 As a general rule electro-magnetic force or strength is di- 
 rectly proportional to the strength of the current, and to the 
 number of windings of the wire, but independent of the na- 
 ture and thickness of the wire. 
 
 It is on the principle of the electro-magnet that all 
 telegraphing is done. 
 
CHAPTER XXXVI. 
 
 VOLTAIC INDUCTION. 
 
 Induction by the voltaic current is the action which cur- 
 rents or magnets exert on conductors. 
 
 Currents thus produced are called induction ox faradic 
 currents. 
 
 Induction can be produced by : 
 
 Magnets. 
 
 Interrupted currents. 
 
 Continuous currents. 
 
 A current upon itself. 
 
 a. If a magnet be introduced into the centre of a hol- 
 low coil of insulated wire, at the moment of introduction 
 and withdrawal a momentary current will be excited in 
 the coil of wire. These excited currents are opposite in 
 direction. 
 
 b. Induction by interrupted currents can be produced 
 by introducing an insulated coil of wire, called primary, 
 into another insulated coil, called the secondary, and 
 passing a current of electricity through the primary. 
 
 At the moment of making and breaking this current, 
 a secondary current will be excited in the secondary coil, 
 but in opposite directions, viz. : at the moment of making 
 in the inverse direction to that in the primary coil, and in 
 the same direction at the time of breaking. 
 
 c. By continuous currents. When a primary coil is 
 traversed by a continuous current and brought near a 
 
 84 
 
Electricity and Magnetism. 85 
 
 secondary coil, or is removed from it, currents are excited 
 in this secondary coil as were produced by the interrupted 
 currents. 
 
 d. Induction can be excited by a current on itself 
 when two portions of the same insulated wire are placed 
 side by side, the sudden making and breaking of a current 
 in one wire will excite a current in the other, called extra. 
 The making of this current is a hindrance to the passage 
 of electricity throughout the length of the wire, for the 
 extra current is an inverse one, but the breaking intensi- 
 fies the current, as it is in the same direction as the 
 current itself. 
 
 By placing a core of soft iron in the interior of any of 
 the coils above mentioned for the production of induced 
 currents, the effect will be intensified, the iron acting as 
 a magnet when the current is transmitted around it. 
 
 The following law governs induced currents : The 
 strength of the induced currents is proportional to the in- 
 ducing currents and to the products of the lengths of the 
 inducing and induced currents. 
 
 APPARATUS FOUNDED ON INDUCTION. 
 
 The following apparatus is founded on induction : 
 
 Magneto-electrical machines. 
 
 Induction coils. 
 
 Faradic battery. 
 
 Telephone. 
 
 a. The magneto-electrical machine in its simplest form 
 consists of a horse-shoe magnet around which two bob- 
 bins are made to revolve. The wire forming these bob- 
 bins is coiled on two cylinders of soft iron jointed by 
 plates of iron or brass, thus forming electro-magnets. So 
 that the induced currents produced may be in the same 
 
86 Physics. 
 
 direction, the wire on the bobbins is coiled in opposite di- 
 rections. By each complete revolution of the electro- 
 magnet, its two armatures become alternately magnetized 
 in contrary directions, and in each wire an induced cur- 
 rent is produced, the direction of which changes at each 
 half turn. By aid of a commu7iicator the currents may all 
 be made to pass in the same direction. 
 
 The difference between a dynamo and a magneto-electric 
 machine is that in the former we have electro-magnets 
 and in the latter permanent ones. 
 
 In the large magneto-electric machines like those now 
 used for electric lighting, electro-gilding, electrolysis, etc., 
 as many as 64 such bobbins are used and made to revolve 
 around the poles of horse-shoe magnets. About 235 rev- 
 olutions per second produce the greatest degree of light. 
 
 For the electric light it makes no difTerence if the cur- 
 rents are produced in opposite directions, but for other 
 purposes the current must be made to pass in the same 
 direction by means of the communicator. 
 
 b. Induction coils, of which Rhumkorff' s is a good ex- 
 ample, are arrangements for producing induced currents 
 of electricity by means of electric currents whose circuits 
 are opened and closed alternately in rapid succession. 
 
 These coils consist essentially of hollow cylinders, pri- 
 mary and secondary, in which are placed bundles of iron 
 wire. The primary coil is connected with the poles of a 
 battery, the current of which is alternately opened and 
 closed by a self-acting arrangement called an interrupter, 
 while the other serves for the development of the induced 
 current. 
 
 By means of an apparatus of this kind, currents of elec- 
 tricity are produced superior in effects to those obtained 
 by electrical machines or Ley den batteries. In Rhumkorff' s 
 
Electricity and Magnetism. 87 
 
 machine there is placed in the bottom a condenser macje of 
 tin-foil so insulated that each alternate layer, forming one 
 coating, is connected with the inducing current, thus 
 storing up some of the electricity from the battery and 
 extra currents, while the remaining layers, forming a 
 second coating, are connected with the secondary or in- 
 duced currents, thus increasing their strength by using 
 this stored-up electricity. 
 
 c. In the faradic battery the current from a galvanic 
 cell is made to pass through a coil of insulated wire called 
 the helix, vihxcSx surrounds a bundle of soft iron wire to be 
 magnetized. When the wires are magnetized by the cur- 
 rent it draws the interrupter toward it, thus breaking the 
 circuit and demagnetizing the wires. The interrupter re- 
 turning to its place reconnects the circuit, and the same 
 steps are repeated. As the current is an alternating one 
 the polarity changes with each interruption. The pri- 
 mary helix is usually surrounded by a secondary one, 
 which has no connection with the battery cell, but re- 
 ceives its current by induction from the primary coil, and 
 is of very high tension. 
 
 This secondary current is modified in strength by a 
 sliding tube of metal which passes between the two coils, 
 thus regulating the amount of induction. 
 
 The rheophores are connected at will with either the 
 primary or secondary coils, and thus made to transmit 
 either the primary or secondary currents. 
 
 d. The telephone is an instrument whose action depends 
 upon the fact that whenever the relative positions of a 
 magnet and a closed coil of wire are altered there is pro- 
 duced within the coil a current of electricity. The magnet 
 and the coil in the telephone remain fixed, but the iron 
 membrane or diaphragm in the mouthpiece, which vi- 
 
88 Physics. 
 
 brates backward and forward when spoken into, becomes 
 magnetized by induction from the magnet. These vibra- 
 tions give rise to currents in the coil surrounding the 
 permanent magnet, which are transmitted through the 
 circuit to the distant coil surrounding its magnet, which 
 in turn alternately attracts and ceases to attract the cor- 
 responding diaphragm, thus producing similar sounds by 
 exciting vibrations in the air. 
 
 In Bell's telephone an electro-magnet is used instead of 
 the permanent magnet in the closed coil of wire. 
 
 The diaphragm vibrating before this electro-magnet 
 produces induced currents in the circuit, which are trans- 
 mitted to the corresponding electro-magnet in the re- 
 ceiver, producing like vibrations in that diaphragm. 
 
 In Edison's telephone a plate of carbon is interposed in 
 the circuit, and the diaphragm is made to vibrate against 
 that, thus alternately increasing and diminishing the 
 pressure on the carbon. It has been found that the car- 
 bon under different pressure transmits the electric cur- 
 rent with different intensities, producing the same result 
 as adding induced currents to the circuit, and therefore 
 causing like vibrations in the diaphragm of the receiver. 
 
 The microphone is an apparatus working on the same 
 principle as the Edison telephone. Compression of the 
 carbon diminishes the resistance of an electric current, 
 while a diminution of the commission greatly increases it. 
 The carbons of this instrument are so arranged that the 
 waves of sound are communicated to them, altering their 
 electric conduction so that very weak sounds are plainly 
 heard in an attached telephone receiver. 
 
CHAPTER XXXVII. 
 THERMO-ELECTRIC CURRENTS. 
 
 Currents of electricity can be produced by applying 
 heat or cold to one of the junctions of a circuit composed 
 of different metals. 
 
 The electricity thus produced is called thermo-electric 
 currents. 
 
 In the thermo-electric pile a large number of elements or 
 metals are used in a small space, and alternately soldered 
 together. 
 
 The elements may be of many kinds, or, better still, 
 many elements of the same kind. 
 
 89 
 
PART II. 
 
 THEORETICAL CHEMISTRY. 
 
 91 
 
THEORETICAL CHEMISTRY. 
 
 Chemistry treats of the atomic composition of matter, 
 and of ttiose changes in matter which result from a re- 
 arrangement of these atoms. 
 
 Matter is any thing we can appreciate by our senses, 
 and is made up of sixty-six elements, or substances that 
 cannot be divided into other substances. 
 
 Matter may be divided into : 
 
 Atoms. 
 
 Molecules. 
 
 Masses. 
 
 Atoms are the smallest divisions of matter, and unite to 
 form molecules. 
 
 A molecule is the smallest group of atoms, that will ex- 
 hibit the physical and chemical properties of the substance, 
 and cannot be divided without losing these characteristics. 
 
 A mass is a collection of molecules. 
 
 COMPOSITION OF MOLECULES. 
 
 The composition of a molecule is ascertained by : 
 
 a. Analysis, which consists in separating the molecule 
 into its constituent atoms ; and 
 
 b. Synthesis, which consists in uniting the constituent 
 atoms to form the molecule. 
 
 The atoms thus composing any molecule may be alike, 
 forming elemental molecules ; or unlike, forming compound 
 
 93 
 
94 Theoretical Chemistry. 
 
 molecules. Rearrangement of the atoms in any elemental 
 molecule yields no new kind of matter, as does the re- 
 arrangement of atoms in compound molecules. 
 
 There have been found but sixty-six such elemental 
 molecules or substances, and these have received the name 
 of elements. 
 
 From these sixty-six kinds of atoms, all masses of mat- 
 ter are made up. 
 
 These elements are all named, and each name has, for 
 convenience, received a symbol. They are as follows : 
 
 TABLE OF ELEMENTARY BODIES, WITH THEIR SYMBOLS 
 AND ATOMIC WEIGHTS. 
 
 
 TABLE I. 
 
 
 NAME. 
 
 SYMBOL. 
 
 ATOMIC WEIGHT. 
 
 Aluminum, 
 
 Al 
 
 27.4 
 
 Antimony, 
 
 Sb 
 
 120 
 
 Arsenic, 
 
 As 
 
 75 
 
 Barium, 
 
 Ba 
 
 137 
 
 Bismuth, 
 
 Bi 
 
 206.5 
 
 Boron, 
 
 B 
 
 II 
 
 Bromine, 
 
 Br. 
 
 80 
 
 Cadmium, 
 
 Cd 
 
 112 
 
 Caesium, 
 
 Cs 
 
 133 
 
 Calcium, 
 
 Ca 
 
 40 
 
 Carbon, 
 
 C 
 
 12 
 
 Cerium, 
 
 Ce 
 
 141 
 
 Chlorine, 
 
 CI 
 
 35-5 
 
 Chromium, 
 
 Cr 
 
 52.4 
 
 Cobalt, 
 
 Co 
 
 58.8 
 
 Copper, 
 
 Cu 
 
 634 
 
 Didymium, 
 
 D 
 
 144.78 
 
 Erbium, 
 
 E 
 
 165.9 
 
 Fluorine, 
 
 F 
 
 19 
 
Theoretical Chemistry. 95 5 
 
 NAME. 
 
 SYMBOL. 
 
 ATOMIC WEIGHT. 
 
 Fluorine, 
 
 F 
 
 19 
 
 Gallium, 
 
 Ga 
 
 68.8 
 
 Glucinum, 
 
 Gl 
 
 9 , 
 
 Gold, 
 
 Au 
 
 197 
 
 Hydrogen, 
 
 H 
 
 I 
 
 Indium, 
 
 In 
 
 1 1 3-4 
 
 Iodine, 
 
 I 
 
 127 
 
 Iridium, 
 
 Ir 
 
 192 
 
 Iron, 
 
 Fe 
 
 S6 
 
 Lanthanium, 
 
 La 
 
 138.S 
 
 Lead, 
 
 Pb 
 
 207 
 
 Lithium, 
 
 Li 
 
 7 
 
 Magnesium, 
 
 Mg 
 
 24 
 
 Manganese, 
 
 Mn 
 
 54 
 
 Mercury, 
 
 Hg 
 
 200 
 
 Molybdenum, 
 
 Mo 
 
 96 
 
 Nickel, 
 
 Ni 
 
 58.8 
 
 Niobium, 
 
 Nb 
 
 94 
 
 Nitrogen, 
 
 N 
 
 14 
 
 Osmium, 
 
 Os 
 
 199.2 
 
 Oxygen, 
 
 
 
 16 
 
 Palladium, 
 
 Pd 
 
 105.7 
 
 Phosphorus, 
 
 P 
 
 31 
 
 Platinum, 
 
 Pt 
 
 194.4 
 
 Potassium, 
 
 K 
 
 39-1 
 
 Rhodium, 
 
 Rh 
 
 104.4 
 
 Rubidium, 
 
 Rb 
 
 85.4 
 
 Ruthenium, 
 
 Ru 
 
 104.4 
 
 Scandium, 
 
 Sc 
 
 44 
 
 Selenium, 
 
 Se 
 
 78.8 
 
 Silicum, 
 
 Si 
 
 28 
 
 Silver, 
 
 Ag 
 
 108 
 
 Sodiflm, 
 
 Na 
 
 23 
 
 Strontium, 
 
 Sr 
 
 87.6 
 
9^ Theoretical Chemistry. 
 
 NAME. 
 
 SYMBOL. 
 
 ATOMIC WEIGHT. 
 
 Sulphur, 
 
 S 
 
 32 
 
 Tantalum, 
 
 Ta 
 
 182 
 
 Tellurium, 
 
 Te 
 
 128 
 
 Thallium, 
 
 Tl 
 
 204 
 
 Thorium, 
 
 Th 
 
 233 
 
 Tin, 
 
 Sn 
 
 118 
 
 Titanium, 
 
 Ti 
 
 50 
 
 Tungsten, 
 
 W 
 
 184 
 
 Uranium, 
 
 U 
 
 238 
 
 Vanadium, 
 
 V 
 
 51.2 
 
 Ytterbium, 
 
 Yb 
 
 172.7 
 
 Yttrium, 
 
 Y 
 
 89.8 
 
 Zinc, 
 
 Zn 
 
 65.2 
 
 Zirconium, 
 
 Zr 
 
 89.6 
 
 NUMBER OF ATOMS IN ELEMENTAL MOLECULES. 
 
 From the law of Ampfere : Equal volumes of all bodies in 
 the gaseous state contain the same number of molecules, it 
 follows, that the m,olecules of all bodies when in the gaseous 
 state are of the same size ; and their weight compared to 
 that of hydrogen is proportional to the weight of any given 
 volume, compared with the same volume of hydrogen. For 
 example, if one volume of hydrogen gas contains one 
 hundred molecules, then an equal volume of chlorine will 
 contain one hundred molecules. 
 
 If these volumes be mixed together and exposed to 
 the sunlight, they will unite and form two volumes of 
 hydrochloric-acid gas, containing two hundred molecules. 
 
 The atomicity of any molecule is the number of atoms 
 which it contains. Most of the elements contain two 
 atoms to the molecule, but mercury, cadmium, zinc, 
 and barium contain one ; ozone, three ; phosphorus and 
 arsenic, four ; and sulphur, six. * 
 
Theoretical Chemistry. 97 
 
 ATOMIC AND MOLECULAR WEIGHTS. 
 
 The atomic weight of any atom is its relative weight 
 compared to hydrogen, which is taken as unity (i). 
 
 The molecular weight of any molecule is the sum of the 
 atomic weights of its constituents. 
 
 Thus the molecular weights of chlorate of potash, 
 KCIO3, would be : 
 
 Atomic weight, 
 
 K 39.1 
 
 CI. 35-5 
 
 Os(i6x3) 48. 
 
 122.6 
 
 By dividing the atomic weight of any of these con- 
 stituent elements into the molecular weight of the com- 
 pound, the proportion by weight of each element is deter- 
 mined. Thus in chlorate of potash (KClOg), one third of 
 it by weight is oxygen. The atomic weight of oxygen 
 is 16, but as there are three atoms, their combined atomic 
 weight would be 48 (16x3). The molecular weight of 
 the compound is 122.6; therefore the weight of the oxy- 
 gen would be 1^, or over one third. 
 
 ATOMIC EQUIVALENCE. 
 
 The equivalence of any atom is the quantity of its com- 
 bining power expressed in hydrogen units, which has a 
 combining power of i. 
 
 These atoms having the combining power of one (i) are 
 called monads ; of two (2), diads ; of three (3), triads, etc. 
 Many atoms have more than one combining power — that 
 is, they may have an equivalence of i, 3, 5, etc., or 2, 4, 
 6, etc., but this combining power in the same kind of 
 atoms always increases or diminishes by two. 
 
98 
 
 Theoretical Chemistry. 
 
 Atoms whose equivalence is even are called artiads ; 
 those whose equivalence is odd, perissads. The following 
 table gives the most constant equivalence of elements : 
 
 TABLE II. 
 
 MONADS. 
 
 Hydrogen. 
 
 Fluorine. 
 
 Chlorine, i, iii, v, vii. 
 
 Bromine, i, iii, v, vii. 
 
 Iodine, i, iii, v, vii. 
 
 Lithium. 
 
 Potassium. 
 
 Silver. 
 
 TRIADS. 
 
 Antimony, iii, v. 
 Bismuth, iii, v. 
 Boron. 
 Gold, i, iii. 
 Nitrogen, i, iii, v, vii. 
 Phosphorus, i, iii, v. 
 Arsenic, iii, v. 
 
 HEXADS. 
 
 Chromium, ii, iv, vi. 
 I Manganese, ii, iv, vi. 
 
 Iron, ii, vi, (Feg)"" 
 Cobalt ii, (Cog) ''• 
 Nickel, ii, (Ni^)"- 
 
 For example. Hydrogen is a monad and chlorine is a 
 monad ; consequently one atom of hydrogen will just sat- 
 urate one atom of chlorine. Again, hydrogen being a 
 monad and oxygen a diad, it will take two atoms of hy- 
 drogen to saturate one of oxygen, etc. 
 
 DIADS. 
 
 Strontium. 
 
 Barium. 
 
 Magnesium, 
 
 Zinc. 
 
 Cadmium. 
 
 Cerium. 
 
 Mercury (Hgg)"" 
 
 Copper (Cug)"- 
 
 Oxygen. 
 
 Sulphur, ii, iv, vi. 
 
 Calcium. 
 
 TETRADS. 
 
 Carbon. 
 Silicon. 
 Tin, ii, iv. 
 Aluminum (Alg)"- 
 Platinum, ii, iv. 
 Lead, ii, iv. 
 
Theoretical Chemistry. 99 
 
 Iron, Cobalt, Nickel, Mercury, Copper, and Aluminum, 
 frequently unite with other elements by the use of two 
 atoms as well asione. The equivalence of these elements 
 when combining with the use of double atoms is given in 
 the above Table II. 
 
 Thus one atom of mercury (Hg), which is a diad, will 
 combine with two of chlorine, which is a monad, or two 
 atoms of mercury (Hgg), will combine with two of chlorine, 
 thus making entirely different compounds (Hg Clg) and 
 (Hg, Cy. 
 
 The graphic symbol of any atom is one indicated by a 
 circle with lines radiating from it equal in number to its 
 combining power. Thus an atom of hydrogen would be 
 indicated by a circle with one radiating line — oxygen 
 with two lines, etc. 
 
 MULTIPLICATION OF ATOMS AND MOLECULES. 
 
 Atoms are multiplied by placing a numeral below and 
 to the right of its symbol. Thus C indicates one atom of 
 carbon ; Cg, two atoms of carbon, etc. 
 
 Molecules are multiplied in the same way, after inclos- 
 ing their symbols in brackets, or by placing the numerals 
 before the molecular formula. Thus, (HgO), or 2HgO 
 would represent two molecules of water ; (HgO)3 or 
 3HgO, three molecules of water, etc. 
 
 When the number of atoms of any constituent in a 
 molecule is more than one, this is indicated by a numeral 
 placed below and to the right of its symbol. Thus CO3 
 would represent one molecule of carbon dioxide. 
 
 NEGATIVE AND POSITIVE ATOMS. 
 
 In considering the formation of acids, bases, and salts, 
 the atoms constituting them are either positive or nega- 
 tive. 
 
lOO Theoretical Chemistry. 
 
 K positive atom is one which is attracted to the negative 
 pole in electrolysis. 
 
 A negative atojn is one which is attracted to the positive 
 pole in electrolysis. 
 
 Hydrogen and the metallic or basic elements are 
 usually positive, while oxygen, nitrogen, chlorine, and the 
 other so-called acid elements are negative. 
 
 CHEMICAL FORMULAS. 
 
 A compound molecule is one whose constituent atoms 
 are unlike. 
 
 The representation of any compound molecule by sym- 
 bols is called 3. formula. Thus, HCl is hydrochloric acid ; 
 HgO, water, etc. 
 
 Formulas may be empirical, rational, graphic, or typical. 
 
 An empirical formula is one derived from analysis, and 
 is merely an expression of the kind and relative number 
 of atoms in any molecule. Thus, HgS04 would be the 
 empirical formula for sulphuric acid. 
 
 A graphic formula expresses the kind and absolute 
 number of atoms, together with the arrangement and 
 equivalence of each. 
 
 Thus O 
 
 II 
 H-0-S-O-H would be 
 
 II 
 O 
 
 the graphic formula for sulphuric acid. 
 
 A rational formula is one giving the kind and number 
 of atoms, split up into groups, showing of what it is com- 
 posed and into what elements or molecules it may be 
 decomposed by means of reagents. 
 
 Thus, H^O, SO3 is a rational formula of sulphuric acid 
 
Theoretical Chemistry. lOi 
 
 The typz formula is one built up on the plan or struc- 
 ture of some well-known chemical compound. The 
 water-type formula H-O-H is the most common. By- 
 replacing one or more H's with negative or positive 
 atoms, bodies are said to be formed upon the water type. 
 Thus K-O-H is the water-type formula for potassium 
 hydrate. 
 
 Besides the water type of compounds there are several 
 other types, the most important being the hydrochloric- 
 acid-type, the ammonia type, and the marsh-gas type. 
 
 In the hydrochloric-acid type, H-Cl, by the replacing of 
 the hydrogen atom by other atoms, as sodium, potassium, 
 etc., a new class of compounds is formed, as sodium and 
 potassium chloride, etc. 
 
 The ammonia type H 
 
 H— N— H 
 is also an important type, especially in the formation of 
 organic compounds. These compounds are formed by 
 replacing one or more of the hydrogens by other atoms. 
 Thus by replacing one hydrogen there remains (NHg), 
 called amodogen, which, acting as a monad radical, can 
 unite with the monad potassium, forming (NHg) K, or 
 with the diad calcium, by taking two molecules of the 
 radical, forming (NHg) g Ca. 
 
 H 
 
 I 
 The marsh-gas type, H — C — H 
 
 H 
 
 is also an important type in organic chemistry. New 
 compounds are formed by substituting other atoms in the 
 place of one or more hydrogens. 
 
102 Theoretical Chemistry. 
 
 NAMING MOLECULES. 
 
 Biniary molecules are those containing two atoms di- 
 rectly united, as Na-Cl. 
 
 Ternary molecules are those whose dissimilar atoms are 
 united by a third atom, as K-O-H. 
 
 The names of all compound molecules are derived from 
 those of their constituents. 
 
 When the constituent atoms of binary molecules have 
 but one equivalence, as sodium and chlorine, the termina- 
 tion ide is generally added to the negative element. Thus, 
 NaCl is sodium z\Aoxide. Magnesium and oxygen each 
 have an equivalence of two, hence MgO is magnesium 
 oxide, etc. 
 
 In cases, however, where the constituent atoms have 
 more than one equivalence, as, for example, nitrogen, which 
 has an equivalence of 3 and 5 usually, then the compound 
 with the lower equivalence takes the termination ous, and 
 the higher one ic. Thus nitrogen, a triad, uniting with 
 oxygen, a diad, the result- is nitrous oxide. Again, nitro- 
 gen, a pentad, uniting with oxygen, a diad, the result is 
 nitric oxide. 
 
 Compound molecules having a lower equivalence still 
 than the oi^s, the prefix hypo is attached ; or if higher than 
 the ic, the prefix per. Thus, theoretically, nitrogen may 
 be a monad or a septad, and if united to oxygen, a diad, 
 there would be formed hypo-nitrous oxide and /^r-nitric 
 oxide. 
 
 In a few cases the number of atoms combining to form 
 the molecule is indicated in naming the substance. Thus, 
 CO3 is called carbon di-oxide, because there are two 
 atoms of oxygen, which distinguishes it from CO, carbon 
 mon-oxide. 
 
 The term sesqui, when prefixed to a binary molecule, 
 
Theoretical Chemistry. 103 
 
 indicates that the atoms bear a relation to each other of 
 3 to 2. Thus FegOj is sesquioxide of iron. 
 
 Sub prefixed to a chemical compound means lower or 
 lesser, and is frequently used synonymously with ous. 
 
 CONSTRUCTION OF MOLECULES. 
 
 When atoms with different equivalents unite to form 
 compounds, each atom, must furnish the same number of 
 bonds, this number being the least common multiple of 
 their atomic equivalence ; and the number of atoms re- 
 quired by each constituent is obtained by dividing the 
 least common multiple by the equivalence of each atom. 
 
 Thus, if nitrogen is a triad and oxygen a diad, both 
 must furnish six bonds (2x3 = 6), the least common mul- 
 tiple of 2 and 3. To furnish these bonds, nitrogen, which 
 already has three bonds, must furnish two atoms (6-^-3 
 := 2), while oxygen, having but two bonds, must furnish 
 three atoms (6-^2 = 3). 
 
 The formula formed by this union of nitrogen and oxy- 
 gen must be NgOg, N=0 
 
 >o 
 
 N=0 
 
 SATURATED AND UNSATURATED MOLECULES. 
 
 When the bonds of all the atoms constituting a mole- 
 ctile are mutually combined, the molecule is called satu- 
 rated ; but when some of the bonds remain free, the 
 molecule is unsaturated, and the group of atoms compos- 
 ing it form a compound radical. 
 
 When the unsaturated atoms are all of the same kind, 
 the group is called a simple radical. 
 
 As radicals cannot exist in a free state in nature," they 
 enter into combination with other atoms as do single 
 
I04 Theoretical Chemistry. 
 
 atoms, and take the termination yl. Thus, in water 
 (HgO), if one hydrogen is removed there remains HO, a 
 compound radical called hydroxy//. 
 
 As hydrogen is a monad and oxygen a diad, HO has 
 one free bond which may unite with any atom having one 
 free bond, as potassium, forming KOH, or with other 
 radicals having one free bond, as NO, thus forming 
 HNOg. 
 
 In some cases artiad radicals, or compound radicals with 
 an even number of free bonds, can exist free in nature by 
 mutual saturation of these free bonds. Thus CO, car- 
 bonal or carbon-mon-oxide is a diad radical, carbon having 
 four bonds, only two of which are saturated by oxygen, 
 but as the remaining bonds saturate each other (< C = O) 
 it may exist free in nature. 
 
 In perissad radicals, however, this can never take place, 
 for there always exists an odd number of free bonds, con- 
 sequently the union of any one free bond with another 
 would still leave the molecule unsaturated 
 
 It is by this mutual saturation of bonds that a triad may 
 become a monad, or a tetrad a diad, etc. 
 
 THE FORMATION OF ACIDS, BASES, AND SALTS. 
 
 An acid molecule is one consisting of one or more nega- 
 tive atoms united by oxygen to hydrogen, (Cl-O-H) and 
 has the property of turning' vegetable blues — as litmus- 
 red. 
 
 It is sometimes called a salt of hydrogen. 
 
 Acids are formed from the oxides of negative elements 
 by the addition of a molecule of water. 
 
 Thus ClgO is an oxide of chlorine; add water (ClgO + 
 HgO = 2 HCIO) and an acid of chlorine (HCIO) is 
 formed. 
 
Theoretical Chemistry. 105 
 
 Ortho acids. Primary acids, or those in which all the 
 oxygen has a linking function, are called ortho, and the 
 number of oxygen and hydrogen atoms must be equal. 
 For example: arsenious acid, HgAsOg, is an ortho acid, 
 for all the H's are linked to As by O. Thus : 
 
 /O— H 
 
 As--0— H 
 
 \0— H 
 
 Meta acids. Meta acids are derived from the ortho by 
 taking from them one or more molecules of water, thus 
 forming mono-, di-, or tri-meta acids. For example: 
 HgAsOg is an ortho-arsenious acid ; taking away HgO we 
 have HAsOg, a meta arsenious acid. 
 
 Pyro acids mean those having reverted or changed their 
 chemical formula by means of heat. H^PgO, is pyro- 
 phosphoric acid. 
 
 A basic molecule is one consisting of one or more posi- 
 tive atoms united by oxygen to hydrogen. 
 
 Thus, sodium hydrate (NaOH) is a base. Sodium is a 
 positive atom united by oxygen to hydrogen, Na-O-H. 
 
 Many chemists define a base as a metallic oxide, and a 
 basic element as a metallic element. 
 
 A saline molecule is one consisting of one or more posi- 
 tive atoms united by oxygen to one or more negative atoms. 
 
 Thus NaOCl is a salt of sodium. Sodium is a positive 
 atom united by oxygen to Jjiti-egcn; a negative atom, <5. 
 Na-O-Cl. 
 
 These acids, bases, and salts are formed on the plan of 
 the structure of water (H-O-H), commonly called the 
 water type. Thus exchanging for one of the hydrogens 
 a negative atom an acid is formed, for a positive atom a 
 base ; and by exchanging both hydrogens, one for a neg- 
 ative and the other for a positive atom, a salt is produced. 
 
io6 Theoretical Chemistry. 
 
 Chemically speaking, a salt is usually produced by the 
 action of an acid upon a base, or, theoretically, by re- 
 placing one or more of the hydrogens of any acid by basic 
 elements. 
 
 There are three kinds of salts, called acid, normal, and 
 double. An acid salt is one in which all the hydrogens 
 of the acid have not been replaced by basic elements, as 
 disodium phosphate (NagHPO^). 
 
 An acid salt sometimes takes the prefix of super or bi 
 as in jM/^r-phosphates or ^2-carbonates. 
 
 A normal salt is one in which all the hydrogens have 
 been replaced, as sodium phosphate (NagP04). 
 
 A double salt is one in which the acid hydrogens are re- 
 placed by more than one kind of basic elements, as am- 
 monio-magnesium phosphate (NH4), MgPO^. 
 
 NAMING ACIDS AND SALTS. 
 
 As compound molecules take the terminations ous and 
 ic and the prefixes, hypo and per, according to the num- 
 ber of equivalence of their constituent atoms, so when 
 acids are formed by the union of hydrogen by oxygen to 
 these compound molecules, they also take like termina- 
 tions. 
 
 Thus hyponitrous oxide united to hydrogen by oxygen 
 forms hyponitrous acid. In the same way is formed 
 nitrous acid and nitric acid* 
 
 In a like manner any salt produced by the action of an 
 ous acid forms an ite salt, while an ic acid forms an ate salt 
 either with or without the prefixes hypo and per. Thus 
 we have by the action of xntxous acid on sodium hydrate 
 the formation of sodium mtxite, while the action of mine 
 acid on the same base forms sodium rCitrate. 
 
Theoretical Chemistry. I07 
 
 CHEMICAL REACTIONS. 
 
 All molecules are subject to chemical change, and any 
 change taking place among the atoms constituting any 
 molecule is called chemical reaction. 
 
 This change is expressed by molecular formulae, the 
 chemical reactions being represented in the form of equa- 
 tions. Thus let AB be one molecule of any substance to 
 be acted upon by another molecule CD, then the equation 
 would be expressed thus : AB -\- CD = AD + CB. As no 
 loss of weight can be the result of any chemical change, 
 then the molecular weight of the two sides of the equa- 
 tion must be equal, and also the number of atoms. 
 
 If the chemical change results in the production of any 
 s ubstanc e ins oluble in the naenstiuum e nriployed . such a 
 compound will appeai:,as_a preci^tate. If, on the con- 
 trary, a volatile substance is produced by such a chemical 
 change, itjvill,^ evolved as a gas or vapor. 
 
PART III. 
 
 INORGANIC CHEMISTRY. 
 
 loq 
 
INORGANIC CHEMISTRY 
 
 CHAPTER I. 
 
 Inorganic chemistry treats of all the elements, both me- 
 tallic and non-metallic, in their free and combined states 
 as they occur in the inorganic world. 
 
 The chemistry of plants and animals is treated of under 
 organic chemistry, or chemistry of the carbon compounds. 
 
 In the consideration of each element, the following 
 order of arrangement will assist the student in memorizing 
 the facts in their most important relations : 
 
 I. The name of the element, its symbol, atomic weight, 
 and equivalence. 
 
 II. Its history. 
 
 III. Its occurrence. 
 
 IV. Its preparation. 
 
 V. Its properties. 
 
 a. Physical. 
 
 b. Chemical. 
 
 VI. Its uses. 
 
 VII. Its compounds. 
 
 HYDROGEN. 
 
 Symbol H. Atomic weight i. Equivalence I. 
 
 History. Hydrogen was discovered in 1766 by Caven- 
 dish, who described it under the name of inflammable air. 
 
 Occurrence. Hydrogen exists free in certain volcanic 
 gases, in or around the sun and some of the fixed stars. 
 
112 Inorganic Chemistry. 
 
 In the combined state it is found in water, in all animal 
 and vegetable tissues, petroleum, etc. 
 Preparation : 
 
 1. Water (HgO), by means of electrolysis', will separate 
 into its constituent atoms, oxygen collecting at the positive 
 and hydrogen at the negative pole. Thus : 
 
 Water. Hydrogen. Oxygen. 
 
 H,0= H, + O. 
 
 2. If metallic sodium is thrown upon water, the water 
 is decomposed, and hydrogen is set free. Thus : 
 
 Water. Sodium. Sodium hydrate. Hydrogen. 
 
 HgO + Na = NaOH + H. 
 
 3. By the action of sulphuric acid upon metallic zinc, 
 the sulphuric acid is decomposed and hydrogen set free. 
 Thus : 
 
 Sulphuric acid. Zinc. Zinc sulphate, Hydrogen. 
 
 H2SO4 + Zn = ZnSO^ + H^ 
 
 4. By passing heated steam over anthracite coal. Thus : 
 
 Coal. Water. C. Monoxide. Hydrogen, j 
 
 lie + 2H,0 .= ilCO^+ 2H2. 1^ 
 This when passed over naphtha to keep it together \)Z- 
 comes water gas. 1,0-i^^^y^^ ^ Xi^ -^ "^^ 
 Properties : 
 
 a. Physical. Hydrogen is a colorless, odorless, and 
 tasteless gas. It is the lightest form of matter known, 
 hence its diffusibility is greater than any other gas. It is 
 but slightly soluble in water. 
 
 b. Chemical. Hydrogen is combustible — that is, at an 
 elevated temperature it will combine with oxygen with the 
 evolution of light and heat. It will not support combus- 
 tion. It burns with a pale blue flame, and with an intense 
 heat. Its product of combustion is water. 
 
 Uses. Hydrogen on account of its lightness is used to 
 inflate balloons. It is used also as a heating agent on 
 account of its high temperature produced by combustion. 
 
CHAPTER II. 
 
 OXYGEN. 
 
 Symbol O. Atomic weight i6. Equivalence W. 
 
 History. Oxygen was first discovered by Priestley in 
 1774, and described by him as dephlogisticated air. 
 Scheele discovered it independently the next year, and 
 called it empirical air. 
 
 Occurrence. Oxygen is the most abundant element 
 in nature. It forms one fifth part of the atmosphere, 
 where it exists free. In the combined state it forms two 
 thirds of the globe — water being two thirds and minerals 
 one half oxygen by weight. It is found combined with 
 other elements in all animal and vegetable tissues. 
 
 Preparation : 
 
 1. Mercuric oxide exposed to a high temperature is 
 decomposed and metallic mercury and oxygen are pro- 
 duced. Thus : 
 
 Mercuric-oxide. Mercury. Oxygen. 
 
 HgO = Hg + O. 
 
 2. Carbon dioxide (CO3) in the leaves of plants is de- 
 composed by the sunlight into carbon and oxygen. 
 Thus : 
 
 Carbon dioxide. Carbon. Oxygen. 
 
 COa = C + Og 
 
 3. By electrolysis of water described under the chapter 
 on hydrogen. 
 
 4. It is prepared from the oxygen of the air in the fol- 
 lowing manner: 
 
 113 
 
114 Inorganic Chemistry. 
 
 1. Pure air is passed over a heated mixture of manga- 
 nese dioxide (MnO^) and sodium hydrate (NaOH), thus 
 forming sodium manganate (Na3Mn04) and water HgO. 
 Thus: 
 
 Mang. dioxide. Sod. hydrate. Sod. manganate. Water. 
 
 MnOg + 2NaOH + air = Na^MnO^ + H3O. 
 
 2. This heated sodium manganate (Na2Mn04) is then 
 raised to a high temperature, and a current of steam 
 passed over it, which decomposes it into its original con- 
 stituents again, and setting oxygen free from its mixture 
 with hydrogen. Thus: 
 
 Sod. manganate. Water. Mang. dioxide. Sod. hydrate. Oxygen. 
 
 NagMnO^ + HgO = MnOg + 2NaOH -f O. 
 
 This process can be kept up continually, and oxygen 
 manufactured in large quantities. 
 
 5. The usual method of preparing oxygen for com- 
 merce is by heating chlorate of potash (KCIO3), which 
 yields a large quantity of oxygen. Thus : 
 
 Potass, chlorate. Potass, chloride. Oxygen. 
 
 KCIO3 = KCl -f 3O. 
 Properties : 
 
 a. Physical. Oxygen is a colorless, odorless, and taste- 
 less gas. It is a little heavier than air and but slightly 
 soluble in water. 
 
 b. Chemical. Oxygen enters into combination with 
 all the elements except fluorine. 
 
 The combination of any element with oxygen really 
 constitutes combustion, but the term is usually restricted 
 to those combinations of oxygen which are accompanied 
 with heat and light, the usual result if the oxidation is 
 a rapid one. 
 
 As the result of oxidation, oxides are produced. 
 ' Uses. Oxygen is used for aiding combustion for pur- 
 poses of either heat or light. 
 
Inorganic Chemistry. 115 
 
 In the air, diluted with nitrogen, its uses for respiratory- 
 purposes are well known. 
 
 COMPOUNDS OF OXYGEN AND HYDROGEN. 
 HYDROGEN OXIDE OR WATER. 
 
 Formula, H3O or H — O — H. 
 
 History. Water was considered an elementary sub- 
 stance until Lavoisier, in 1773, proved its compound 
 nature. 
 
 Occurrence. Water occurs abundantly in nature, both 
 free and combined. Occurring in the free state it is 
 either : 
 
 Atmospheric or 
 
 Terrestrial. 
 
 I. Atmospheric water occurs in the form of rain, snow, 
 hail, mist, etc. 
 
 II. Terrestrial waters are : 
 Sweet, 
 
 Salt 
 Mineral. 
 
 a. Sweet water is found in : 
 
 1. Springs. 
 
 2. Rivers. 
 
 3. Lakes. ' 
 
 4. Wells. 
 
 b. Salt water is found in : 
 
 1. Oceans. 
 
 2. Inland seas. 
 
 c. Mineral waters are those that contain an excess of 
 mineral ingredients, and are named from their principal 
 constituents. Thus : 
 
 1. Saline, containing chlorides and sulphates. 
 
 2. Alkaline, containing bicarbonates. 
 
Ii6 Inorganic Chemistry. 
 
 3 
 
 Chalybeate, containing ferrous bicarbonates. 
 
 4. Acid — containing free acids, usually sulphuric. 
 
 5. Alum, containing alum or potash alum. 
 
 6. Acidulous, containing carbonic acid. 
 Sulphur, containing sulphites, HgS, and sulphides. 
 Borax, containing borax. 
 Silicious, containing sodium silicate. 
 
 Saratoga waters are alkaline and contain large quanti- 
 ties of common salt NaCl. 
 
 Water in the combined state presents four degrees of 
 combinations, as : 
 
 a. Hydroscopic moisture, or that which can be driven 
 off at a temperature of 212° F. 
 
 b. Water of crystallization. 
 
 c. Chemical combination, also called hydration. 
 
 d. Solvent. Not always a mere mechanical solution, 
 for heat or cold is often the result. 
 
 Ingredients of water. Natural waters are seldom pure — 
 that is, they contain more than the constituent elements, 
 hydrogen and oxygen. 
 
 Water always contains a certain amount of mineral 
 matter, such as potassium, sodium, calcium, and magne- 
 sium in the form of chlorides, bicarbonates, and sulphates. 
 Besides this mineral matter, it also contains organic mat- 
 ter derived from the decomposition of plants, and gases 
 in solution derived from the air. 
 
 Preparation. Water is always the product of combus- 
 tion in presence of oxygen. It can be prepared by direct 
 union of its constituents mixed in proper proportion by 
 means of an electric spark. It is also the result of many 
 chemical combinations. 
 
 Properties : 
 
 a. Physical. Water is a colorless, odorless, and taste- 
 
Inorganic Chemistry. wj 
 
 less liquid. A poor conductor of heat and electricity. 
 It is taken as the standard for the specific gravity of 
 liquids. Its maximum density is at 4° C, it expanding for 
 all lower and higher temperatures. It freezes at o°C., 
 forming a crystalline solid — ice ; and is converted into 
 vapor or steam at 100° C. 
 
 Most gases are soluble in water ; it dissolves them in 
 proportion to their volume and not their density. 
 
 b. Chemically, water is very active, entering into chem- 
 ical combination with many substances. Thus : 
 
 Calcic oxide. Water. Calcic hydrate. 
 
 CaO + H3O = Ca(OH)g. 
 
 Efflorescent substances are those that lose their water of 
 crystallization and become powdered. 
 
 Deliquescent substances are those that attract moisture 
 and liquefy. 
 
 Uses. Water is used for manufacturing and domestic 
 purposes, and may contain ingredients which make it unfit 
 for either. 
 
 The ingredients present which render the water harm- 
 ful for manufacturing purposes are the minerals, especially 
 the calcium salts, which are deposited in the boilers as 
 calcium carbonate (CaCOg). This salt is not soluble in 
 pure water, but is soluble in water containing carbonic 
 acid (HgCOj). Thus : 
 
 Calc. carbonate. Carbonic acid. Gale, bicarbonate, 
 
 CaCOg + HgCOg = CaH3(C03)2. 
 This salt is soluble in water, but upon the application of 
 heat it is decomposed into carbonic dioxide and calcium 
 carbonate. Thus : 
 
 Calc. bicarbonate. Water. Carbon dioxide. Calc. carbonate. 
 
 CaHg (COj)^ = H3O -\- COg + CaCOg. 
 This calcium carbonate depositing on the inside of boilers 
 
1 1 8 Inorganic Chemistry. 
 
 destroys them. An apparatus called the calcium catcher 
 is sometimes attached to boilers to remedy this danger. 
 Saw-dust and other foreign substances are sometimes put 
 in the boilers for the calcium to deposit upon instead of 
 upon their iron plates. 
 
 Slacked lime and alum (i gr. to gallon) will, when 
 added to water, precipitate the lime salts which will not 
 form incrustations, and are therefore frequently used for 
 that purpose. 
 
 In water for domestic use the presence of mineral mat- 
 ter does no harm unless the water contains much calcium, 
 which renders it " hard," and hence poor for washing and 
 cooking purposes. 
 
 It is here, however, that the organic matter present 
 may or may not prove very harmful to health. If the 
 organic matter present in the water be due to the de- 
 composition of vegetable matter, and it is not great in 
 amount, it will do no harm. 
 
 If, on the contrary, the organic matter is the result of 
 animal impurities, sewage, etc., in which disease germs 
 are often present, it may be the means of causing much 
 sickness. Boiling the water will destroy these impurities, 
 but freezing will not. 
 
 The presence of much chlorine, ammonia, or nitrites in 
 the water renders it suspicious — chlorine, for it indicates 
 sewage contamination ; ammonia, organic matter ; and 
 nitrites, animal decomposition. 
 
 Tests : 
 
 a. For chlorine. Add to the water a little nitric acid 
 (HNO3) and then nitrate of silver (AgNOg). The chlo- 
 rine is precipitated in white flakes, as the chloride of 
 silver. 
 
 b. For organic matter. Add permanganate of potash 
 
Inorganic, Chemistry. 119 
 
 to the water; if much organic matter is present it will 
 oxidize the potash solution and thus destroy its color. 
 
 c. For ammonia. Add to the water a little " Nessler 
 reagent " — a solution of iodide of mercury (Hgig) and 
 caustic potash (KOH), — and if ammonia is present it will 
 turn the water a dark yellow color ; the more the am- 
 monia, the darker the solution. 
 
 To make a complete analysis of drinking-water, find the 
 amount of: 
 
 1. Total solids. 
 
 2. Volatile organic matter. 
 
 3. Chlorine. 
 
 4. Sodium chloride. 
 
 5. Free ammonia. 
 
 6. Nitrates. 
 
 7. Nitrites. 
 
 8. Albuminoid ammonia. 
 
 9. Hardness. 
 
 The water should also be examined microscopically, for 
 by this means bacteria, micro-organisms, and various 
 organic substances are discovered, and, if found suspicious 
 by their presence, " cultures " may be produced by adding 
 a drop of the water to sterilized gelatine. 
 
 HYDROGEN DIOXIDE OR FREE HYDROXYL. 
 
 Formula. HgOg. H-O-O-H. 
 
 Preparation. It is always the result of slow oxidation, 
 and is prepared by the action of carbonic or hydrochloric 
 acid (HgCOg or HCl) upon barium oxide. Allowing the 
 water present to evaporate slowly, leaves the HgOg behind 
 as a syrupy liquid. Thus : 
 
 Barium oxide. Carbonic acid. Barium carbon. Free hydroxy]. 
 
 BaOg + H2CO3 = BaCOg + HgOg. 
 
I20 Inorganic Chemistry. 
 
 Properties. Hydrogen dioxide is a colorless, syrupy- 
 liquid, which decomposes at temperatures over ioo° into 
 water and oxygen. As it evolves oxygen readily, it is an 
 oxidizing agent. 
 
 Uses. It is used in bleaching vegetable colors and as an 
 antiseptic. 
 
 OZONE. 
 
 Symbol O3. Molecular weight, 48. 
 
 Ozone is not an element but a form of oxygen with 
 three instead of two atoms to a molecule, and sometimes 
 described as active oxygen. 
 
 History. Although ozone was really discovered in the 
 eighteenth century, Schonbein, in 1840, was the first to 
 describe it. 
 
 Occurrence. Ozone is found free in the air, especially 
 after a thunder-shower. It is probably produced also in 
 the atmosphere by the growth of plants. 
 
 Preparation : 
 
 1. Electricity. By its passage through the air, as by 
 lightning, or by the electrolysis of water acidulated with 
 hydrochloric acid (HCl), ozone is formed. 
 
 2. Ozone is prepared by the slow oxidation of phos- 
 phorus or sulphur. Thus : 
 
 Phosphorus. Oxygen. Phosphoric oxide. Ozone. 
 
 P2 + 30a = P^O, + O3. 
 or by the rapid oxidation of red-hot platinum. 
 Properties : 
 
 a. Physical. Ozone is a colorless gas with an odor like 
 that of weak chlorine. It is a little heavier than oxygen. 
 
 b. Chemically it is a more active oxidizer than oxygen. 
 It bleaches strongly and is poisonous to animal life, 
 
 although easily converted into oxygen. It decomposes 
 potassium iodide (KI), setting free iodine vapor, which 
 
Inorganic Chemistry. 121 
 
 colors starch solution blue. This acts as a test for the 
 presence of ozone. 
 
 Uses. Ozone is a powerful bleaching agent, and as it 
 readily oxidizes it is used by many as a disinfectant for 
 water-closets, etc., to destroy foul odors. 
 
CHAPTER III. 
 
 NITROGEN. 
 
 Symbol'^. Atomic weight 14. Equivalence \-\l\-Y . 
 
 History. Nitrogen was discovered by Rutherford, in 
 1772, in the air which had been breathed by animals. 
 
 Occurrence. Nitrogen is found free in the atmosphere. 
 In the combined state it is found in the ammonia com- 
 pounds, nitrates and nitrites, and in many of the animal 
 and vegetable tissues. 
 
 Preparation. The easiest way to obtain nitrogen is 
 from the air, where it exists in a free state. This is 
 accomplished by using the accompanying oxygen by 
 combustion — in other words, by burning out the oxygen. 
 
 Chemically it is prepared by heating ammonium nitrite 
 (NH4NO2), thus breaking it up into water and nitrogen. 
 Thus : 
 
 Ammonium nitrite. Water. Nitrogen. 
 
 (NHJNO^ = (H,0), + Ng. 
 
 Properties : 
 
 a. Physical. Nitrogen is a colorless, odorless, and 
 tasteless gas. It is lighter than air and soluble in water. 
 
 b. Chemical. Nitrogen is very inert, entering directly 
 into combination with very few elements. In combina- 
 tion, however, it is very active, forming corrosive and ex- 
 plosive mixtures as nitric acid, nitro-glycerine, etc. It 
 will not support combustion. 
 
Inorganic Chemistry. 123 
 
 Uses. One of the principal uses for nitrogen is a nat- 
 ural one in diluting the oxygen of the air so as to render 
 it suitable for respiratory purposes, and for limiting its 
 oxidizing properties. 
 
 THE ATMOSPHERE. 
 
 Composition. The atmosphere is made up of a mixture 
 of normal and abnormal ingredients. These are : 
 
 1. J-wormai. parts per 100. 
 
 I. Oxygen, 
 
 20.50 
 
 2. Nitrogen, 
 
 78.00 
 
 3. Watery vapor. 
 
 1.40 
 
 4. Carbon dioxide. 
 
 .05 
 
 5. Ozone, 
 
 trace 
 
 6. Gaseous hydrocarbons, 
 
 trace 
 
 7. Hydrogen sulphide, 
 
 trace 
 
 8. Ammonia, 
 
 trace 
 
 9. Acids, 
 
 trace 
 
 Total, 
 
 100.00 
 
 II. Abnormal. 
 
 
 A. Dead matter. 
 
 
 a. Mineral. 
 
 
 I. Sand. 
 
 
 2. Clay. 
 
 
 3. Cosmical dust. 
 
 
 4. Sodium chloride 1 , 
 
 "J „ , . 1 1, 4. ^ ^I'O'^ sea water. 
 
 5. Calcium sulphate ) 
 
 
 
 b. Non-mineral. 
 
 
 I. Animal substances. 
 
 
 2. Vegetable substances. 
 
 
 3. Excrements. 
 
 
 4. Products of decomposition. 
 
 
124 Inorganic Chemistry. 
 
 (CO, 
 
 5. Sewer gas. < HgS CH4. 
 (NH3 
 B. Live matter. 
 I. Pollen of plants. 
 
 ! Disease germs. 
 Fungi. 
 Yeast plant. 
 
 Ground air is that found in the earth down to the level 
 of the water. It is apt to be very unwholesome, as it 
 takes up microbes from the sewers and bad water which 
 percolates through the ground. This air readily gains ac- 
 cess to houses through the cellars unless they are properly 
 cemented. 
 
 Properties : 
 
 a. Physical. Air is one of the standards used for the 
 specific gravity of gases. It exerts a pressure of 15 lbs. 
 to the square inch on the surface of the earth. The 
 height of the atmosphere is not known, but probably ex- 
 ists for fifty miles above the earth, its density diminishing 
 as it ascends. 
 
 b. Chemical. It is a mixture of oxygen and nitrogen, 
 and not a chemical union. The gases do not separate on 
 account of the law governing their diffusion. 
 
 The atmosphere is a good supporter of combustion and 
 a poor conductor of heat and electricity. It is slightly 
 soluble in water. 
 
 Uses. The most important use of the atmosphere is 
 for respiratory purposes. 
 
 The most deleterious ingredient in the air is the disease 
 germs. These are especially found in sewer gas and are 
 conveyed to the air mechanically from sewage by bubbles. 
 
Inorganic Chemistry. 125 
 
 Compounds 
 
 I. OF NITROGEN AND HYDROGEN. 
 
 HYDROGEN NITRIDE, OR AMMONIA. 
 H 
 
 Formula: H3 N or N — H. 
 
 I 
 H 
 
 History. Ammonia has been known for many cen- 
 turies, but the name was not given it until 1781 by Breg- 
 man. 
 
 Occurrence. It occurs but sparingly in nature, a little 
 being found in water, air, soil, and animal matter. 
 
 Preparation. The compounds of ammonia are usually 
 prepared by the destructive distillation of animal matter, 
 or from the ammoniacal liquor obtained from distillation 
 of coal. 
 
 Ammonia gas is best prepared by the action of quick- 
 lime (CaO) upon ammonium chloride (NH^Cl). Thus: 
 
 Ammonium chloride. Calcic oxide. Calcic chloride. Water. Ammonia. 
 
 (NH^Cl)^ -f CaO = CaCl, + H,0 + (H3N),. 
 
 a. Physical. Ammonia is a colorless, pungent, and al- 
 kaline gas, turning red litmus paper blue. It is very ^vol- 
 atile, lighter than air, and freely soluble in water. Will 
 not saponify fats. 
 
 b. Chemically, it will not support combustion, and is 
 slightly combustible at elevated temperatures. It is 
 readily decomposed by heat and electricity into nitrogen 
 and water. 
 
 2. OF NITROGEN AND OXYGEN. 
 As nitrogen has an equivalence of I., III., and V., we 
 have by combination with oxygen several oxides of nitro- 
 gen. Thus : 
 
126 Inorganic Chemistry. 
 
 N 
 
 > O 
 
 N NgO or hyponitrous oxide. 
 
 II 
 N 
 
 > O 
 
 N NgO 3, or nitrous oxide. 
 
 II 
 
 O 
 O 
 
 II 
 0=N 
 
 > O 
 0=N NjjOj, or nitric oxide. 
 
 II 
 O 
 
 From these oxides, acids are formed on the plan of the 
 water type by substituting for an atom of oxygen in each 
 of the oxides two hydroxyls (OH) ; or by adding a mole- 
 cule of water to each. Thus : 
 N-O-H 
 
 N-O-H, (HNO)3 =: NgO + HgO, (HNO)^, or hyponi- 
 trous acid. 
 
 NgOj -f HgO = (HN0g)2, or nitrous acid. 
 NgOg -f H3O = (HNOg)^, or nitric acid. 
 
 The salts of these acids are formed theoretically by re- 
 placing the hydrogen by basic elements. 
 
 HYPONITROUS OXIDE. 
 
 Formula: NjO. 
 
 Preparation. Hyponitrous oxide is prepared by heat- 
 ing ammonium nitrate (NH4NO3), which decomposes 
 into hyponitrous oxide and water. Thus : 
 
 Ammonium nitrate, Hyponitrous oxide, Water. 
 
 NH4NO3 = NgO -1- sHjO. 
 
Inorganic Chemistry. 127 
 
 Properties : 
 
 a. Physical. It is a colorless, odorless gas with a 
 sweetish taste. It is commonly called " laughing-gas," 
 or nitrous oxide. When inhaled it produces insensibility. 
 It is heavier than air and soluble in water. 
 
 b. Chemical. It supports and accelerates combustion 
 by being decomposed by heat and its oxygen set free. 
 
 Uses. As an anesthetic. 
 
 NITROUS ACID. 
 
 O 
 
 II 
 Formula : HNOg, N— O— H 
 
 Properties. Nitrous acid is a very unstable compound. 
 It is a bluish liquid, and has to be kept at a low tempera- 
 ture or it will decompose into nitric acid (HNO3), water, 
 and nitrogen dioxide NgOg. Thus: 
 
 Nitrous acid. Nitric acid. Water. Nitric dioxide. 
 
 3HNO, = HNO3 + H3O + NgO,. 
 The salts formed from the union of nitrous acid and a 
 base are called nitrites, and are much more stable com- 
 pounds than the acid. 
 
 NITRIC ACID. 
 
 o 
 
 II 
 
 Formula.: HNO,, N— O— H, 
 II 
 O 
 
 Preparation. Nitric acid is prepared by heating a mix- 
 ture of sulphuric acid (H2SO4) and a nitrate, usually 
 sodium nitrate (NaNOg). The sulphuric acid unites with 
 the sodium. Thus : 
 
 Sod. nitrate. Sulpli. acid. Hyd. sod. sulph. Nitric acid. 
 
 2NaN03 + H2SO4 = Na2S04 + zHNOj. 
 
128 Inorganic Chemistry. 
 
 Properties : 
 
 a. Physical. Nitric acid is a colorless, fuming, cor- 
 rosive, and poisonous fluid, heavier than water. 
 
 b. Chemically it is a powerful oxidizing agent. Many 
 such substances as glycerine cotton, sugar, etc., are con- 
 verted into explosives by the action of nitric acid. Mixed 
 with hydrochloric acid (HCl), in the proportion of i to 3, it 
 will dissolve gold, hence this mixture is called aqua regia. 
 
 When nitric acid contains some of the nitrous acid it is 
 then cs^^A fuming nitric acid, for the nitrous acid decom- 
 poses and sets free nitrogen dioxide, which, combining 
 with the oxygen of the air, forms yellowish fumes of 
 nitrogen teroxide (N3O4). 
 
 The union of nitric acid with bases forms nitrates, such 
 as the nitrate of potash (KNO3). 
 
 Uses. Nitric acid is used for etching, for the manufac- 
 ture of explosives, and for oxidizing purposes. 
 
 Besides the regular oxides of nitrogen already con- 
 sidered, there are two others in which nitrogen having 
 the equivalence of III. and V. — two of the bonds saturate 
 each other. Thus : 
 
 N=0 
 
 I 
 N = 0, NgOg or nitrogen dioxide. 
 
 O 
 
 II 
 N=0 
 
 I 
 N=0, N3O4 or nitrogen teroxide. 
 
 II 
 O 
 
 NITROGEN DIOXIDE. 
 
 Formula : N g O g . 
 
 Preparation. It is prepared by reducing nitric acid, 
 HNOp, by metals, as copper, silver, etc. Thus : 
 
Inorganic Chemistry. 129 
 
 Copper. Nitric acid. Copper nitrate. Water. Nitrogen dioxide. 
 
 CU3 + (HN03)8 = 3Cu (NO3), 4H,+0 +N2O,. 
 
 Properties. It is a colorless gas and heavier than air. 
 It does not support combustion, but has strong attrac- 
 tions for oxygen. 
 
 It will unite with the oxygen of the air, forming the 
 yellowish-brown suffocating fumes of nitrogen teroxide 
 (N3O4). This is the vapor which arises from the chemi- 
 cal batteries using nitric acid and has such a disagreeable 
 odor. 
 
 As nitrogen has an equivalence of I., III., and V., and 
 oxygen of II., then NO or N — O — , 
 
 O O 
 
 II II 
 
 NOg or N— O— , and NO3 or N— O— 
 
 II 
 O 
 
 may all be considered as compound radicals, with one 
 free bond, and by union with basic elements form salts. 
 Thus : 
 
 KNO or (NO)-K is potassium hyponitrite ; 
 NaNOg or (NOg^Na is sodium nitrite; 
 
 (NO3) 
 Ca (N0g)2 or > Ca (calcium having two bonds), 
 
 (NO3) 
 is calcium nitrate. 
 
CHAPTER IV. 
 
 CARBON. 
 
 Symbol Q,. Atomic weight 12. Equivalence II. and IV. 
 
 History. Carbon in one form or another has been 
 known for centuries. 
 
 Occurrence. Carbon in the free state exists only as a 
 soHd, but in three distinct forms. 
 
 1. Diamond. 
 
 2. Graphite. 
 
 3. Coal. 
 
 Chemically these substances are the same, but physi- 
 cally entirely different. 
 
 In the combined state carbon exists in the air, lime- 
 stone, petroleum, and in all animal and vegetable tissues. 
 
 DIAMOND. 
 
 History and occurrence,. The diamond was found to 
 consist only of carbon by Lavoisier, in 1776, who burned 
 it in oxygen and obtained as a product of this combustion 
 carbon dioxide (CO^)- 
 
 It is found principally in India and Brazil. 
 
 Preparation. Diamonds have never been prepared 
 physically or chemically. 
 
 Properties : 
 
 a. Physical. The diamond is a crystalline, transparent, 
 and solid body with a very high refractive and dispersive 
 
 130 
 
Inorganic Chemistry. 131 
 
 power. It is the hardest substance known, and a very 
 poor conductor of heat and electricity. 
 
 b. Chemically little is known of the diamond except 
 that it is combustible at a high temperature, and com- 
 posed of carbon alone. 
 
 Uses. Diamonds are used as ornaments and for cutting 
 hard substances, such as glass., ,-» '^}- dtvSiMA , 
 
 GRAPHITE. 
 
 Occurrence. Graphite is found in the United States, 
 England, Ceylon, and many other places as pure carbon. 
 Properties : 
 
 a. Physical. It is a crystallizable, soft, blackish solid, 
 friable and oily to the touch. It is a good conductor of 
 heat and electricity, and has a metallic lustre, 
 
 b. Chemically it is combustible only at high tempera- 
 tures and with some difficulty, and is composed entirely 
 of carbon. 
 
 Uses. It is used as a polish for metals, such as iron, 
 preventing the formation of rust. It is also used in the 
 manufacture of lead-pencils and crucibles. 
 
 COAL. 
 
 Carbon as coal exists in two varieties. 
 
 a. Charcoal. 
 
 b. Mineral coal. 
 
 CHARCOAL. 
 
 Occurrence. Charcoal is not found free in nature, but 
 is the result of destructive distillation. 
 
 Preparation. It is obtained by heating animal or vege- 
 table matter to redness in nearly closed vessels. In this 
 
132 Inorganic Chemistry. 
 
 way the volatile matters are driven off, leaving the carbon 
 behind. 
 Properties : 
 
 a. Physical. Charcoal is a black, porous, soft solid, 
 and very light. It will absorb gases to a great extent, 
 and is a good decolorizer. 
 
 b. Chemically it is a good oxidizer and very combus- 
 tible. 
 
 Uses. It is used largely as a disinfectant by absorbing 
 and oxidizing noxious gases, also as a decolorizing agent 
 in refining sugar, and as a fuel. 
 
 MINERAL COAL. 
 
 Occurrence. It is found in nature as anthracite, bitu- 
 minous, and cannel coal, the first being much the purest 
 carbon. It is the result of geological changes taking 
 place in primitive vegetation, and is thus the product of 
 vegetable life ; the anthracite variety is of the oldest 
 formation. 
 
 Properties : 
 
 a. Physical. Coal is an amorphous, hard, black, heavy 
 solid, with more or less lustre. 
 
 b. Chemically it is combustible with some difficulty, 
 and is not composed of pure carbon. 
 
 Uses. Coal is used principally for heating and illumi- 
 nating purposes. 
 
 All three forms of carbon are alike in being non-vola- 
 tile, solid, and remaining unaltered in the air at ordinary 
 temperatures. They are not subject to decay. 
 
 Compounds 
 
 I. OF CARBON AND HYDROGEN. 
 These compounds are called hydrocarbons, and many 
 of them belong exclusively to organic chemistry. 
 
Inorganic Chemistry. 133 
 
 HYDROGEN CARBIDE. 
 
 Synonyms. Methane, marsh gas, and fire-damp. 
 
 H 
 
 II 
 Formula: CH^ or H — C — H 
 
 II 
 H 
 
 Occurrence. It occurs free in nature as " marsh gas " 
 by the decomposition of vegetable matter under water, 
 and also in coal mines as fire-damp. 
 
 Properties : 
 
 a. Physical. It is a colorless, odorless, and tasteless 
 
 gas, slightly soluble in water, and next to hydrogen in 
 lightness. 
 
 b. Chemically it is combustible, burning with a slightly 
 luminous flame. With air it forms an explosive mixture. 
 Methane forms the first of a homogeneous series of or- 
 ganic compounds with the general formula of C„Hg„4.0, 
 that is, having twice as many hydrogen atoms as carbon, 
 plus 2. 
 
 Uses. It is used in some localities as an illuminating 
 agent. 
 
 HYDROGEN DICARBIDE. 
 
 Synonyms. Carburetted hydrogen, olefiant gas, and 
 ethylene. 
 
 Formula; CgH^. 
 
 Occurrence. It has been found free in nature among 
 the gases in coal mines. 
 
 Preparation. It is prepared by the destructive distilla- 
 tion of coal in making illuminating gas. 
 
 Properties : 
 
 a. Physical. It is a colorless gas with a sweetish taste 
 and odor. It is soluble in water and lighter than air. 
 
134 Inorganic Chemistry. 
 
 b. Chemical. It is combustible, burning with a brilliant 
 white but smoky flame. When mixed with oxygen it is 
 very explosive. 
 
 Uses. For illuminating purposes principally. 
 
 DIHYDROGEN DICARBIDE. 
 
 Synonym. Acetylene. 
 
 Formula. H^Cg. 
 
 Preparation. Acetylene is prepared by the direct union 
 of its constituents at a high temperature, as when the 
 carbon points of the electrodes of a powerful chemical 
 battery are brought near together in an atmosphere of 
 hydrogen. It is produced in all cases of incomplete com- 
 bustion. 
 
 Properties : 
 
 a. Physical. It is a colorless gas, soluble in water, 
 and has a very disagreeable odor. 
 
 b. Chemically it is combustible, burning with a bright 
 smoky flame. 
 
 It combines readily with some metals, as copper and 
 silver, thus forming violently explosive compounds. 
 
 2. OF CARBON AND OXYGEN. 
 
 CARBON DIOXIDE. 
 
 Formula : COg or C — O. 
 
 II 
 O 
 
 History. In 1520 Paracelsus discovered this gas, and it 
 was the first one distinguished from the air. 
 
 Occurrence. It is found free in the air, especially in 
 volcanic regions, and as it is a regular product of combus- 
 tion and fermentation it is found in large quantities where 
 such processes are going on. 
 
Inorganic Chemistry. 135 
 
 It is often found in large quantities in low places, as at 
 the bottom of wells, and called choke damp. In combina- 
 tion it exists in large quantities in limestone. 
 
 Preparation. It is always the product of combustion in 
 presence of oxygen. Thus : 1 
 
 Carbon. Oxygen. Carbon dioxide. 
 
 C + O3 = CO,. 
 Chemically it is prepared by the action of acids, as sul- 
 phuric (H2SO4), on calcic carbonate (CaCOj). Thus : 
 
 Calc. carbonate. Sulph. acid. Gale, sulphate. Water. Carb. dioxide. 
 
 CaCOj -f H3SO4 = CaS04 + HgO + CO, I 
 It is produced in large quantities by burning calcic car- 
 bonate (CaCOj). Thus: 
 
 Calc. carbonate. Calcic oxide. Carbon dioxide. 
 
 CaCOs = CaO + COg 
 
 Properties : 
 
 a. Physical. Carbon dioxide is a colorless, odorless 
 gas with an acid taste, very soluble in water, and \\ 
 times heavier than air. It is fatal to life if breathed in 
 large quantities. 
 
 b. Chemically it will not support combustion, and is 
 non-combustible. By its solution in water it unites with 
 a molecule of water to form carbonic acid (H^COa). 
 Thus : 
 
 Carbonic dioxide. Water. Carbonic acid. 
 
 CO, + H,0 = H.COg 
 
 This acid is readily decomposed by heat into HjO and 
 CO,. 
 
 The salts of carbonic acid are carbonates, and are 
 formed by replacing the hydrogen atoms by basic ele- 
 ments, as calcium, potassium, sodium, etc. 
 
 Uses. Soda waters and effervescent drinks are waters 
 charged with carbon dioxide. 
 
136 Inorganic Chemistry. 
 
 CARBON MONOXIDE. 
 
 Formula : CO. 
 
 Preparation. It is produced by incomplete combus- 
 tion, or by passing carbon dioxide over heated carbon. 
 Thus : 
 
 Carbon dioxide. Carbon. Carbon monoxide. 
 
 CO3 + C = 2CO. 
 
 Properties : 
 
 a. Physical. It is a colorless gas with a suffocating 
 odor, slightly soluble in water, and very fatal to animal life. 
 
 b. Chemical. It is combustible, burning with a blue 
 flame, but will not support combustion. The gas will 
 pass through heated cast-iron and in this way find egress 
 into rooms from stoves or furnaces. 
 
 3. OF CARBON AND NITROGEN. 
 CYANOGEN. 
 Formula : (CN)^ or C^N 
 
 C=N. 
 Symbol. Cy. 
 
 History. It was the first compound radical isolated. 
 Preparation. It is prepared by heating cyanide of mer- 
 cury (HgCyg). Thus : 
 
 Mercuric cyanide. Mercury, Cyanogen. 
 
 HgCy^ = Hg -f Cy,. 
 Properties : 
 
 a. Physical. It is a colorless, poisonous gas, with an 
 odor resembling that of peach blossoms. 
 
 b. Chemical. It is combustible, burning with a bluish 
 flame. Although we have cyanogen existing as such 
 by saturation of its own bonds, still cyanogen (CN) is 
 really a compound radical with an equivalence of one. 
 
Inorganic Chemistry. 137 
 
 Thus by its union with potassium there results potas- 
 sium cyanide (K-CN), with hydrogen, hydrogen cya/- 
 nide (HCN), commonly called hydrocyanic acid or prus- 
 sic acid. 
 
 HYDROCYANIC ACID. 
 
 Formula : HCN or H-CN. 
 
 Preparation. Prussic acid can be prepared pure by 
 passing sulphurated hydrogen (HgS) over dry mercuric 
 cyanide/CH^lS/g)^ Thus : 
 
 Merc, cyanide. Sulph. hydrog^en. Pruss. acid. Merc, sulphide. 
 
 Hg(CN)2 + H3S = 2 HCN + HgS. 
 
 Properties : 
 
 Prussic acid is a volatile liquid with an odor like that 
 of bitter almonds, which contains a little of the acid. 
 It is the most deadly poison known. 
 
 There are a great many cyanogens, but they belong 
 generally to the organic compounds, and hence treated 
 of under Organic Chemistry. 
 
CHAPTER V. 
 
 COMBUSTION. 
 
 Combustion, in the strict sense, is oxidation, but com- 
 monly speaking it is rapid oxidation or oxidation accom- 
 panied by heat and light. 
 
 Products of combustion : 
 
 The products of combustion are of two kinds : 
 
 Physical. 
 
 Chemical. 
 
 a. The physical products are heat and light. 
 
 b. The cAemical products are always water (HgO) and 
 carbon dioxide (COg), the result of hydrogen and carbon 
 burning in presence of oxygen. 
 
 ILLUMINATING GAS. 
 
 History. In 1792 Murdoch made gas illumination a 
 success, it having been observed before this that the 
 gases obtained from the distillation of coal were com- 
 bustible. 
 
 Preparation. Illuminating gas is ordinarily prepared by 
 heating bituminous coal to a high temperature, thus dis- 
 tilling off the combustible gases with their impurities. 
 
 The gas is first passed through pipes, thus condensing 
 the water, gas-tar, and ammonia liquors. It is next passed 
 through the " purifier," which is filled with dry, slacked 
 lime (CaO), separating the other impurities from the gas, 
 3s sulphur compounds and carbon dioxide (COg). 
 
 138 
 
Inorganic Chemistry. 139 
 
 The gas, now freed from impurities, is ready for use- 
 Gas can also be prepared from wood, petroleum, peat,! 
 etc. That prepared from coal is sometimes passed over a 
 carbonator, an apparatus by means of which heavy hydro- 
 carbons are added to the gas from naphtha to make it 
 more luminous. 
 
 Composition of illuminating gas. The principal gases 
 constituting illuminating gas are : 
 
 1. Diluents. 
 
 H. 30 to 60^. 
 
 CH^. Marsh gas, 40 to 70 ^. 
 
 CO. Carbon monoxide, 7 to 13^. 
 
 2. Luminants : 
 
 C2H4. Olefiant gas, 6 to 12 %. 
 CgHg. Acetylene, 6 to 12^ 
 CaH2n. Hydrocarbons, 6 to 12^. 
 
 3. Impurities. 
 C. 
 
 S. 
 N. 
 
 COg. Carbon dioxide. 
 Properties : 
 
 a. Physical- Illuminating gas is colorless, with a very 
 disagreeable, suffocating odor. It is lighter than air and 
 poisonous to animal life. 
 
 b. Chemically it is combustible, burning with a bright 
 yellow flame. The collateral products from coal-gas 
 manufacture are : 
 
 Coke, 
 Gas-tar, 
 
 Ammoniacal liquors. 
 
 Uses. The gases are used for illuminating purposes, the 
 coke for fuel, the ammoniacal liquors for the manufacture 
 
140 Inorganic Chemistry. 
 
 of ammonium salts, and the gas-tar for making anilines, 
 phenols, and hydrocarbons. 
 
 ANIMAL AND VEGETABLE ECONOMY. 
 
 Animals, as a rule, produce in general those chemical 
 substances which plants live upon, and plants produce, in 
 their turn, articles of food for animals. Thus: 
 
 1. Animals produce and plants eat : 
 Carbon-dioxide, CO3. 
 
 Water, HgO. 
 
 Ammonia, NH3. 
 
 Salts, especially salts of K, Na, and Ca. 
 
 2. Plants produce and animals eat : 
 Vegetable products, 
 
 Oxygen. 
 
 PLANTS CONTAIN ; ANIMALS CONTAIN : 
 
 Carbohydrates, 
 
 Fats, Fats, 
 
 Organic acids. 
 
 Resins, 
 
 Essential oils. 
 
 Alkaloids, 
 
 Albuminoids, Albuminoids, 
 
 Water, Water, 
 
 Inorganic salts. Salts. 
 
CHAPTER VI. 
 HALOGEN GROUP. 
 
 Chlorine, bromine, iodine, and fluorine form a group of 
 elements which resemble each other to a marked degree, 
 both physically and chemically. 
 
 They all form salts that contain no oxygen and resemble 
 sea salt, hence called halogen salts, and the elements 
 haloids. 
 
 The ratio between their atomic weights, especially of 
 the chlorine, bromine, and iodine, is nearly constant. 
 
 CHLORINE. 
 
 Symbol C\. Atomic weight ■^t^.t). Equivalence!. 
 
 History. Chlorine was discovered by Scheele in 1774. 
 
 Occurrence. Chlorine never occurs free in nature, but 
 always in combination. It is usually combined with 
 potassium, sodium, magnesium, and other metallic ele- 
 ments. It exists largely in mineral springs a.nd sea water. 
 In the form of common salt (NaCl) it forms vast deposits 
 in the earth's crust. 
 
 Preparation. It is largely prepared by the action of 
 sulphuric acid (HgSO^) upon a mixture of common salt 
 (NaCl) and manganese dioxide (MnOg). Thus: 
 
 Mang. diox. Sod. chloride. Sulphuric acid. Sod. sulphate. Manganic sulphate. 
 
 MnOg + (NaCl)2 + 2H3SO4 = Na3S04 + MnSO^ 
 
 Chlorine. Water. 
 
 + Cl, + (H,0),. 
 141 
 
142 Inorganic Chemistry. 
 
 or by the action of hydrochloric acid (HCl) upon man- 
 ganic oxide (MnOg). Thus : 
 
 Manganic oxide. Hydrochloric acid. Manganous chloride. Water. Chlorine. , 
 
 MnOg + 4HCI = MnClg + (HgO)^ + Cl^. 
 
 Properties : 
 
 a. Physical. Chlorine is a yellowish green gas with a 
 suffocating odor and astringent taste. It is very irritating 
 to the air passages when inhaled, very soluble in water, 
 and much heavier than air. 
 
 b. Chemically it is very active, combining directly with 
 all elements except nitrogen, oxygen, and carbon. 
 
 It combines with free hydrogen in the presence of sun- 
 light to form hydrochloric-acid gas (HCl), and with pow- 
 dered copper, arsenic, antimony, and phosphorus with the 
 evolution of heat and light. Chlorine is combustible in 
 hydrogen gas, but not in oxygen. Chlorine is sometimes 
 called an allotropic element — that is, being capable of ex- 
 isting in two different physical conditions, for in the 
 dark it is much less active than in the light. Free chlorine 
 is a good bleaching agent, for, owing to the attraction of 
 chlorine for hydrogen, water is decomposed, and the oxy- 
 gen set free, which destroys vegetable coloring matters by 
 oxidizing them. 
 
 Bleaching powder is made from the action of chlorine on 
 slacked lime. Thus : 
 
 chlorine. Calcic hydrate. Calcic chloride. Calcic hypochlorite. Water. 
 
 4CI -f 2Ca (OH)2 = CaClg -\- CaCClO)^ + HgO 
 (bleaching powder). 
 
 Uses. Chlorine is used as a bleaching agent and for a 
 disinfectant. The so-called chloride of lime is merely 
 slacked lime impregnated with chlorine gas. 
 
Inorganic Chemistry. 143 
 
 Compounds. 
 
 I. CHLORINE AND HYDROGEN. 
 
 HYDROGEN CHLORIDE OR HYDROCHLORIC ACID. 
 
 Formula. HCl or H-Cl. 
 
 Preparation. Hydrogen chloride may be prepared by 
 direct union of its constituents by mixing equal volumes 
 of chlorine and hydrogen gases, and exposing them to 
 the sunlight. It is commercially made by the action of 
 sulphuric acid (H3SO4) on common salt (NaCl). Thus: 
 
 Sod. chloride. Sulphuric acid. Sod. sulphate. Hydrochloric acid. 
 
 (NaCl)^ + H3SO4 = Na^SO, + (HCl)^. 
 
 Properties : 
 
 a. Physical. Hydrogen chloride is a colorless, pungent 
 acid gas turning blue litmus red, very soluble in water, 
 forming hydrochloric acid. 
 
 b. Chemically the gas is non-combustible. 
 
 The liquid acid dissolves many of the metallic oxides, 
 as antimony, iron, tin, zinc, etc., forming chlorides. 
 
 Uses. Hydrochloric acid is used principally for chemi- 
 cal purposes. 
 
 2. OF CHLORINE AND OXYGEN. 
 
 As chlorine may be a monad, triad, pentad, or heptad, 
 its union with the(monad\oxygen will result in the forma- 
 tion of four oxides. Thus : 
 
 CI 
 
 > O or ClgO, hypochlorous oxide. 
 CI 
 
144 Inorganic Chemistry. 
 
 O 
 
 II 
 CI 
 
 > O or CloOg, chlorous oxide. 
 CI 
 
 II 
 O 
 
 O 
 
 II 
 
 o=ci 
 
 > O or ClgOj, chloric oxide. 
 0=C1 
 
 II 
 O 
 
 o 
 
 II 
 o=ci=o 
 
 > O or ClgO,, perchloric oxide. 
 0=CI=0 
 
 II 
 O 
 
 From these oxides acids are formed on the plan of the 
 water type by substituting two hydroxyls (OH) for an 
 atom of oxygen in each of the oxides, or, which results in 
 the same formula, adding one molecule of water. Thus : 
 
 Cl-OH. 
 
 Cl-OH or (HCIO)^ = ClgO + H^O (HCIO)^ hypo- 
 chlorous acid. 
 
 ClgOg + HgO = (HClOg)^ or chlorous acid. 
 CI3O5 + HgO = (HClOs)^ or chloric acid. 
 Cl^O, -j- HgO = (HC104)2 or perchloric acid. 
 
 The salts of the acids are formed theoretically as usual 
 by replacing the hydrogens with basic elements. 
 
, Inorganic Chemistry. 145 
 
 HYPOCHLOROUS OXIDE AND ACID. 
 
 Formula: CIgO. 
 
 Preparation. It is prepared by passing free chlorine 
 over mercuric oxide, HgO. 
 
 Mercuric oxide. Clilarine. Mercuric cliloride. Hypochlorous oxide. 
 
 HgO + 4CI = HgCI,, + Cl^O. 
 
 Properties : 
 
 a. Physical. It is a yellowish gas with an odor like 
 free chlorine ; very soluble in water. 
 
 b. Chemically it is a very unstable compound, decom- 
 posing easily into chlorine and oxygen. It combines with 
 water to form hypochlorous acidi^QlQ)), which is a very 
 powerful bleaching agent. 
 
 The salts of this acid are called hypochlorites, and are 
 used for bleaching agents and disinfectants, as, for in- 
 stance, the calcium hypochlorite, Ca (C10)2, or solutions 
 of sodium hypochlorf&e, NaClO (jQFJbbarraque solution), 
 and pot. hypochlorite, KCIO (Javelle water). 
 
 CHLOROUS OXIDE AND ACID. 
 
 Formula : CI g O 3 . 
 
 Preparation. Chlorous oxide is prepared by reducing 
 the chlorates by action of nitric acid (HNO3) in presence 
 of a reducing agent, as arsenious acid. 
 
 Properties : 
 
 a. Physical. It is a greenish gas, with a suffocating 
 odor, and very soluble in water. 
 
 b. Chemically, it is a good bleaching agent, and unites 
 with water, forming chlorous acid (HClOg). 
 
 This compound is very unstable, as are its correspond- 
 ing salts the chlorites, as potassium chlorite (KCIO3). 
 
146 Inorganic Chemistry^ 
 
 CHLORIC ACID. 
 
 Formula : HCIO3. 
 
 Preparation. Chloric acid is prepared by the action 
 of sulphuric acid (H2SO4) upon barium chlorate 
 BaCClOj)^. Thus: 
 
 Barium clilorate. Sulphuric acid. Barium sulphate. 
 
 Ba(C103)g + HgS04 = BaS04 
 
 Chloric acid. 
 
 + 2HCIO3. 
 
 Properties. Chloric acid is a very powerful oxidizing 
 agent. It will set paper on fire when dropped upon it. 
 The salts of this acid form chlorates, and are also strong 
 oxidizing agents. 
 
 Uses. The acid and its salts are used as oxidizing 
 agents, and in making pyrotechnical mixtures. Potas- 
 sium 'chlorate is used in making oxygen. 
 
 PERCHLORIC ACID. 
 
 Formula: HCIO4. 
 
 Preparation. Perchloric acid is prepared by heating 
 perchlorate of potassium (KCIO4) with sulphuric acid 
 (H,S04). 
 
 Properties : 
 
 a. Physical. It is an oily, colorless, fuming liquid, 
 with an odor of chlorine. 
 
 b. Chemical. It is a powerful oxidizing agent, setting 
 paper and wood on fire when dropped upon them. Chloric 
 acid and its corresponding salts are the most stable of the 
 chlorine acids and salts. 
 
 BROMINE. 
 Symbol 'Qr. Atomic weight Zo. Equivalence \. 
 History. Bromine was discovered in the water of the 
 Mediterranean Sea in 1826 by Ballad. 
 
Inorganic Chemistry. 147 
 
 Occurrence. Bromine does not occur free in nature, 
 but in combination with metallic elements, as sodium 
 and magnesia ; it is found in sea water and many mineral 
 springs. 
 
 Preparation. It is prepared by evaporating water rich 
 in bromides until the salts are separated by crystalliza- 
 tion, and exposing these to chlorine, which decomposes 
 them, setting bromide free. 
 
 Properties : 
 
 a. Physical. Bromine is a dark, heavy liquid, with a 
 suffocating odor. 
 
 b. Chemically, it is analogous to chlorine, but less 
 active. 
 
 Uses. Bromine is used in photography, and as a bleach- 
 ing and disinfecting agent. 
 
 Compounds. 
 
 a. HYDROGEN AND BROMINE. 
 HYDROGEN BROMIDE OR HYDROBROMIC ACID. 
 
 Formula : HBr or H — Br. 
 
 Preparation. Hydrobromic acid is prepared by bring- 
 ing phosphorus and bromine together in presence of 
 water, when they unite with a loud explosion. Thus : 
 
 Phosphorus, Bronjine. Water. Hydrobro. acid. Fhosph. acid. 
 
 P + Brg + 4H2O = 5HBr + H3PO4. 
 
 Properties : 
 
 a. Physical. Hydrobromic acid is a fuming, colorless 
 gas, with an acid reaction, and very soluble in water. 
 
 The principal salt of this acid is potassium bromide, 
 KBr. It is prepared by heating caustic potash, KOH 
 with bromine. 
 
* 
 
 148 Inorganic Chemistry. 
 
 Pot. hydrate. Bromine. Pot. bromide. Pot. bromate. Water. 
 
 6KOH + 6Br = sKBr + KBrOg + sH^O 
 
 2. BROMINE AND OXYGEN. 
 
 Theoretically, there are oxides and acids of bromine as 
 there are of chlorine, but chemically there are not so many. 
 
 Thus there is hypobromous acid (HBrO) and bromic 
 acid (HBrOj), and from them their corresponding salts, 
 formed by replacing the hydrogens by basic elements, as 
 calcium, forming calcium hypobromite, Ca-(BrO)g, and 
 calcium bromate, Ca(BrO<,)2. 
 
 IODINE. 
 
 Formula I. Atomic weight 127. Equivalence I. 
 
 History. Iodine was discovered in 18 11 by Courtois, in 
 sea water. 
 
 Occurrence. Iodine does not occur free in nature, but 
 is combined with metals in sea water, and with sodium 
 and magnesium in sea-weed. 
 
 Preparation. Iodine is prepared by burning sea-weed, 
 and dissolving this ash or kelp in water, and thus obtain- 
 ing the bitter* or mother liquid. From this it is obtained 
 by a process analogous to that of preparing chlorine. 
 
 Properties : 
 
 a. Physical. Iodine is a black crystalline solid, with a 
 metallic lustre. Heated, it evolves the heaviest vapor 
 known. Iodine is but slightly soluble in water, but 
 readily in alcohol. 
 
 b. Chemically, it is similar to bromine and chlorine, but 
 less active than either. Free iodine turns starch solutions 
 a deep-blue color. 
 
 Uses. Iodine is used principally in photography and 
 medicine. 
 
Inorganic Chemistry. 149 
 
 Compounds. 
 
 1. HYDROGEN AND IODINE. 
 
 HYDROIODIC ACID. 
 
 Formula: HI or H — I. 
 
 Preparation. This acid is prepared, as is also the salt 
 pot. iodide, in the same manner as the corresponding 
 acid and salt of bromine. The reactions are similar, 
 simply substitute one body for the other. 
 
 Properties. Hydroiodic acid is a colorless, fuming acid 
 gas, which is soluble in water. 
 
 2. OF IODINE AND OXYGEN. 
 
 As there are oxides and acids of chlorine and bromine 
 so there are of iodine, the most important of which is 
 iodic «t«k/ ( H I O 3 ) . 
 
 Preparation. Iodic acid may be prepared by oxidizing 
 iodine with nitric acid (HNO3), or by acting upon iodine 
 water with chlorine gas. Thus : 
 
 Iodine. Water. Chlorine. Iodic acid. Hydrochloric acid. 
 
 I + (H,0)3 + SCI = HIO3 + SHCI. 
 
 Properties. 
 
 Iodic acid is a colorless, crystalline solid, slightly soluble 
 in water. 
 
 FLUORINE. 
 
 Symbol F. Atomic weight 19. Equivalence I. 
 
 Occurrence. Fluorine is found in nature combined with 
 calcium, forming calcium fluoride (CaF^) or " fluorspar " ; 
 with sodium (NaF) ; and aluminum (AIF3), forming 
 cryolite. 
 
 Preparation. Fluorine has ngjief been obtained in a 
 free state. 
 
150 Inorganic Cliemistry. 
 
 Properties. Fluorine has never been known to combine 
 with oxygen. 
 
 Compounds. 
 
 HYDROGEN AND FLUORINE. 
 HYDROFLUORIC ACID. 
 
 Formula: HF, or H — F. 
 
 Preparation. Hydrofluoric acid is prepared by acting 
 upon fluorspar by sulphuric acid. Thus : 
 
 Fluoride of calcium. Sulph. acid. Gale, sulph. Hydrofluoric acid. 
 
 CaFg + H2SO4 = CaSO^ + 2HF. 
 
 Properties : 
 
 a. Physical. It is a colorless, fuming acid gas, very 
 irritating to the air tubes when inhaled, and it is more or 
 less corrosive. 
 
 b. Chemically, it has the power of attacking glass by 
 uniting with the silicon to form silicon fluoride. 
 
 Uses. Hydrofluoric acid is used extensively in etching 
 glass. 
 
CHAPTER VII. 
 
 SULPHUR. 
 
 Symbols. Atomic weight 2)2. Equivalence \1-W . 
 
 History. Sulphur has been known from remote ages. 
 
 Occurrence. It occurs free as native sulphur in many 
 volcanic regions. 
 
 In combination it occurs with iron, zinc, arsenic, and 
 many other mineral and metallic elements. It is also 
 found in all animal and many vegetable tissues. 
 
 Preparation. It is prepared by roasting native sulphur 
 or combined sulphur in furnaces, thus driving off the pure 
 sulphur as a vapor, which collects on the sides of the re- 
 ceiver as flowers of sulphur. Some of it is condensed into 
 a liquid^ which is collected in moulds, where it hardens, 
 forming roll sulphur, or brimstone. 
 
 Precipitated sulphur, or lac sulphur, is made by adding 
 an acid to a solution of boiling sulphur and milk of lime. 
 
 Properties : 
 
 a. Physical. Sulphur occurs in three allotropic forms, viz.: 
 
 1. The variety found in nature, which is a brittle crys- 
 talline solid, insoluble in water but" soluble in carbon di- 
 sulphide (CSg). 
 
 2. The second variety is that obtained by the crystal- 
 lization of sulphur fused at a high temperature. 
 
 It occurs as yellowish-brown transparent crystals, in- 
 soluble in carbon di-sulphide, but changes slowly into 
 variety i. . ,, 
 
152 Inorganic Chemistry. 
 
 3. The third variety is obtained by pouring melted 
 sulphur into water; this forms a dark tenacious mass 
 which can be drawn out into threads. It is insoluble in 
 carbon di-sulphide, but slowly changes to variety i. 
 
 b. Chemical. Sulphur is combustible at a tempera- 
 ture of 260° C, burning with a blue flame and forming 
 sulphur dioxide (SO3). Its vapor supports combustion, 
 uniting with metals to form sulphides. 
 
 Uses. Sulphur is used for making sulphuric acid (Hg- 
 SO4), and its vapor for bleaching straws. 
 
 Compounds. 
 
 I, SULPHUR AND HYDROGEN. 
 
 HYDROGEN SULPHIDE. 
 
 H. 
 
 Formula: HgS. S < 
 
 H. 
 
 Occurrence. Hydrogen sulphide exists in volcanic 
 gases and sulphur springs, and is a product of decompo- 
 sition. 
 
 Preparation. It can be prepared by direct union of its ' 
 constituents by means of heat, but it is usually made by 
 the action of sulphuric acid (H3SO4) on sulphide of iron 
 (FeS). Thus: 
 
 Sulphide iron. Sulph. acid. Sulphate iron. Sulphide hydrogen, 
 
 FeS + H2SO4 = FeSO^ + H^S. 
 
 Properties: 
 
 a. Physical. It is a colorless gas with an odor of rot- 
 ten eggs. It is heavier than air and very soluble in water. 
 It is quite poisonous to animal life. 
 
 b Chemically it is combustible, burning with a blue 
 flame. It is easily decomposed by oxidizing agents. It 
 
Inorganic Chemistry. 153 
 
 unites with metallic bases and their oxides to form 
 sulphides. 
 
 Uses. It is used in laboratories as a reagent, uniting 
 with metallic elements in solution to form insoluble sul- 
 phides, which have various colors. 
 
 2. OF CARBON AND SULPHUR. 
 
 CARBON DI-SULPHIDE. 
 Formula: CS,. C = S 
 
 Preparation. Carbon di-sulphide is best prepared by 
 passing sulphur vapor over red-hot charcoal. Thus : 
 
 Carbon. Sulphur. Carbon di-sulphide. 
 
 Properties : 
 
 a. Physical. It is a liquid with an ethereal odor when 
 pure, but when impure has a very disagreeable odor. It 
 is not soluble in water, and has strong refractive proper- 
 ties. 
 
 b. Chemical. When vaporized it is combustible, burn- 
 ing with a bright blue flame. It has remarkable solvent 
 properties, dissolving phosphorus, iodine, sulphur, resins, 
 fats, etc. 
 
 Uses. It is used principally as a solvent, for extracting 
 oils and fats, and for lenses. 
 
 3. OF SULPHUR AND OXYGEN. 
 
 As sulphur may be a diad, tetrad, or hexad, there re- 
 sult from its union with oxygen the following oxides. 
 S=0, or SO, hyposulphurous oxide. 
 
154 Inorganic Chemistry. 
 
 O 
 
 II • 
 
 S=0, or SOg sulphurous oxide. 
 
 • II 
 
 S=0, or SO 3, sulphuric oxide. 
 
 II 
 O 
 
 From these oxides there are formed, on the plan of the 
 
 water type, the following acids : 
 
 OH 
 S< 
 
 OH, or HgSOg, hyposulphurous acid. 
 H3SO3, sulphurous acid. 
 'HgS04, sulphuric acid. 
 
 SULPHUROUS OXIDE AND ACID. 
 Formula: SO^. S=0 
 
 II 
 O 
 
 Occurrence. Sulphurous oxide is found free in volcanic 
 gases. 
 
 Preparation. It is always formed by the combustion of 
 sulphur in the presence of oxygen. Thus : 
 
 Sulphur. Oxyg^en, Sulphurous oxide. 
 
 S + Og = SOg, 
 or by the reduction of sulphuric acid by copper. Thus : 
 
 Copper. Sulphuric acid. Copper sulphate. Sulphurous oxide. Water. 
 Cu + 2HgS04 = CUSO4 + SO3 + 2H3O. 
 
 Properties. 
 
 a. Physical. Sulphurous oxide, or commonly called 
 sulphur di-oxide, is a pungent gas with a suffocating odor; 
 twice heavier than air and freely soluble in water. 
 
 b. Chemical. It is not combustible or a supporter of 
 combustion. It unites with metallic oxides to form sulph- 
 
Inorganic Chemistry. 155 
 
 ites. Combining with a molecule of water it forms 
 sulphurous acid, which is a liquid having an acid reaction. 
 It is a fine bleaching agent, owing to its affinity for 
 oxygen, thus uniting with the oxygen of the water or 
 coloring agents, decomposing the compounds, and setting 
 free hydrogen ; best bleaching agent for woollens and silks. 
 
 Sulphurous acid (H2SO3) is a reducing agent, owing to 
 its affinity for oxygen, which combines with the sulphur- 
 ous acid to form sulphuric acid. By replacing one or 
 more of the hydrogens in sulphurous acid by basic ele- 
 ments, sulphites are formed. When only one of two hydro- 
 gens is thus replaced the product is called an acid salt. 
 
 Uses. Sulphurous oxide is a good disinfectant for sick- 
 rooms. The acid and salts are used for bleaching woollens 
 and preserving" cider, fruits, etc. 
 
 SULPHURIC OXIDE. 
 
 Formula : SOg or 0=5=0. 
 
 II 
 O 
 
 Preparation. Sulphuric oxide is prepared by oxidizing 
 sulphurous oxide by means of heat. 
 
 Properties. It is a wax-like solid — crystallizing, thus 
 resembling asbestos. It melts at 16° C, forming the fluid 
 oxide which has the highest co-efficient of expansion 
 known. It unites with water with great heat, forming 
 sulphuric acid (H2SO4). 
 
 SULPHURIC ACID. 
 
 O 
 
 II 
 
 Formula: H2SO4 or 0=S— OH 
 
 O 
 H 
 
1 56 Inorganic Chemistry. 
 
 Occurrence. It occurs free in some mineral springs, and 
 in the secretions of many animals. Combined with metal- 
 lic elements it occurs in great abundance. 
 
 Preparation. It may be prepared by adding water to 
 sulphuric oxide. Thus: 
 
 Water, Sulphuric oxide. Sulphuric acid. 
 
 H,0 + SO3 = H^SO,. 
 Commercially it is prepared by the four following 
 steps : 
 
 1. Sulphur is burned in the air, thus producing sulphur- 
 ous oxide. Thus : 
 
 Sulphur. Oxygen. Sulphurous oxide. 
 
 s + o, = so^. 
 
 2. This sulphurous oxide (SO3) is then mixed with 
 nitrogen tetroxide, forming sulphuric oxide and nitrogen 
 dioxide (NgOg). Thus : 
 
 Sulphurous oxide. Nitrogen tetroxide. Sulphuric oxide. Nitrogen dioxide. 
 
 2SO2 + N2O4 = 2SO3. + N2O3. 
 
 3. This sulphuric oxide (SO 3) is then mixed with 
 steam (HgO), which unites with it, forming sulphuric acid 
 (HgS04). Thus: 
 
 Sulphuric oxide. Water. Sulphuric acid. 
 
 SO3 + H,0 = H3SO4. 
 
 4. The nitrogen tetroxide (Ng04) is obtained again for 
 use by reoxidation of nitrogen dioxide (NgO^)- Thus: 
 
 Nitrogen dioxide. Oxygen. Nitrogen tetroxide. 
 
 N3O3 + O, = N.O^. 
 
 The NgOg is made by adding nitric acid, HNO3, to 
 copper. See page 129. 
 Properties : 
 
 a. Physical. Sulphuric acid is a colorless, oily, corro- 
 sive liquid, much heavier than water. It is decomposed 
 at high temperatures, and has strong affinity for water. 
 
Inorganic Chemistry. 157 
 
 It will extract moisture from the air, drying it ; and 
 from organic matter, charring it. 
 
 b. Chemically, one or more of its hydrogens may be 
 replaced by basic elements forming sulphates, which are 
 very stable compounds. 
 
 Uses. Sulphuric acid is principally used in the manu- 
 facture of chemicals, as nitric, hydrochloric, phosphoric, 
 and other acids, and commercial products. 
 
 THIONIC ACIDS. 
 
 There are a few sulphur acids — but of little import- 
 ance — which are formed of two atoms of sulphur combin- 
 ing with oxygen and hydrogen instead of one. Thus : 
 
 THIO-SULPHURIC ACID. 
 
 OH— S— OH 
 
 II 
 Formula: HgSgOj or S 
 
 II 
 O. 
 
 Properties : 
 
 The salts formed from this acid used to be called hypo- 
 sulphites, the most important of which is sodium thio- 
 sulphate, Na^SgOg, formed by replacing the hydrogen 
 by the metallic element sodium. 
 
 Uses. This salt is used as a medicine and in pho- 
 tography. 
 
 O 
 
 II 
 0=S— OH 
 Dithionic acid, HgS^Og | 
 
 0=S— OH 
 
 II 
 O 
 
158 Inorganic Chemistry. 
 
 and pyro-sulphuric acid, HgSgO,, are the other acids of 
 sulphur whose salts, as pyro-sulphate of sodium, NagSgO,, 
 are used in the arts and pharmacy. 
 
 Fuming or pyro-sulphuric acid HgSgO, is a mixture of 
 sulphuric acid H3SO4 and sulphuric oxide, SO3. 
 
CHAPTER VIII. 
 
 SILICON AND BORON. 
 
 SILICON. 
 
 Symbol Si. Atomic weight 28. Equivalence IV. 
 
 History. Silicon was first obtained pure by Berzelius 
 in 1823. 
 
 Occurrence. It does not occur free in nature, but in 
 combination with oxygen, aluminum, potassium, etc., it 
 forms a large portion of the rocks making up the earth's 
 crust. 
 
 Preparation. Silicon is prepared by the action of sodi- 
 um (Na) upon potassium fluo-silicate (KgSiFg). Thus : 
 
 Pot, fluo-silicate. Sodium. Pot. fluoride. Sod. fluoride. Silicon. 
 
 KgSiFg + 4Na = 2KF + 4NaF + Si. 
 Properties. It is an amorphous, lustreless powder, very 
 hard, and melting only at a very high temperature. At a 
 still higher temperature it takes fire, forming, by its com- 
 bustion, silicic oxide. 
 
 Compounds : 
 
 I. OF SILICON AND HYDROGEN. 
 HYDROGEN SILICIDE. 
 
 H 
 
 Formula. H>Si. H — Si — H 
 
 I 
 H. 
 
 159 
 
i6o Inorganic Chemistry. 
 
 Preparation. It is prepared by the decomposition of 
 magnesium silicide, MggSi, by hydrochloric acid, HCl. 
 Thus : 
 
 Mag. silicide. Hydrochloric acid. Mag. chloride. Hydrogen silicide. 
 
 MggSi + 4HCI = 2MgCl3 + H^Si. 
 
 Properties. It is a colorless gas, burning with a white 
 flame upon coming in contact with oxygen, thus forming 
 white clouds of silica (SiOg) and water. 
 
 2. OF SILICON AND OXYGEN. 
 SILICA OR SILICON OXIDE. 
 
 Formula: SiOg. 
 
 Occurrence. Silica occurs abundantly in nature as crys- 
 talline quartz, opal, amethyst, agate, etc. It also occurs 
 ,as sand-stone. In combination with metallic oxides form- 
 ing silicates it is very abundant. It is found dissolved in 
 many mineral waters, and as a constituent of many animal 
 and vegetable tissues. 
 
 Preparation. It is prepared by the oxidation of silicon 
 or by the dehydration of silicic acid, HgSiOg. 
 
 Properties : 
 
 a. Physical. Silica occurs in two forms, the crystal- 
 line and amorphous. It is very hard and will scratch glass. 
 It is but slightly soluble in water and only in one acid, 
 hydrofluoric (HF). It is fusible but only at very high 
 temperatures. 
 
 b. Chemical. Silica heated with sodium or potassium 
 hydrate underpressure will dissolve and form " fluid glass," 
 or sodium or potassium silicate. Thus : 
 
 Potass, hydrate. Silica Water. Potass, silicate. 
 
 2KOH + SiOg = HgO -f KgSiOj. 
 If an acid is added to this silicate it will decompose, 
 
Inorganic Chemistry. i6i 
 
 and uniting with the hydrogen of the acid form silicic 
 acid, H4Si04. This acid is a gelatinous substance, not 
 very stable, for it loses a molecule of water upon stand- 
 ing, forming what is called meta-sCi\.c\z acid, HgSiOg. 
 
 By replacing one or more of the hydrogens of either 
 acid by a basic element, silicates are formed. The so- 
 dium and potassium meta-silicates are soluble in water. 
 
 Glass is a double silicate, and there are two principal 
 varieties. 
 
 a. Flint glass, or potassio-lead silicate. 
 
 Pot. silicate. Lead silicate. Silica. 
 
 KgSiOg + PbSiOs -f SiOg. 
 
 Sod. silicate. Lead silicate. Silica. 
 
 NagSiOa + PhSiOj + SiOg. 
 
 b. Crown or window glass, or sodio-calcic silicate. 
 
 Pot. silicate. Gale, silicate. Silica. 
 
 KgSiOg + CaSiOg -|- SiOg 
 
 Sod. silicate, Calc. silicate. Silica. 
 
 NagSiOj + CaSiOg + SiOg. 
 
 BORON. 
 
 Symbol B. Atomic weight \i. Equivalence Wl. 
 
 History. The salts of boron have been known for cen- 
 turies, but pure boron was obtained in 1808. 
 
 Occurrence.' It does not occur free in nature, but in 
 combination with sodium, potassium, and ammonia it is 
 found in many mineral waters, and as mineral deposits 
 in the earth's crust. 
 
 Preparation. It is prepared by the action of sodium 
 (Na) on potassium fluo-borate (KBF4). Thus : 
 
 Pot. fiuo-borate. Sodium. Pot. fluoride. Sod. fluoride. Boron. 
 
 KBF4 -I- 3Na = KF + sNaF -f B. 
 Properties. Boron is a chocolate-colored powder slightly 
 
1 62 Inorganic Chemistry. 
 
 soluble in water. By dissolving it in aluminum it will 
 crystallize, forming a solid having many of the physical 
 properties of the diamond. 
 
 Compounds. 
 
 OF BORON AND OXYGEN. 
 BORIC ACID. 
 
 Formula : B g O g . 
 
 Preparation. It is produced by the combustion of 
 boron or boracic acid, H3BO3, in presence of oxygen. 
 
 Properties. Boric oxide is a colorless, brittle, transpa- 
 rent acid. 
 
 2. OF BORON AND HYDROGEN. 
 
 BORIC OR BORACIC ACID. 
 
 Formula: H3BO3 or OH— B~q^ 
 
 Occurrence. Boric acid occurs free in nature, especially 
 in solution in the waters of volcanic regions. 
 
 Preparation. It is easily prepared by evaporating the 
 waters holding it in solution. 
 
 Properties : 
 
 a. Physical. It occurs as white crystalline scales, sol- 
 uble in water and having an acid reaction. 
 
 b. Chemical. By replacing one or more of the hydro- 
 gens by basic elements, borate salts are formed. 
 
 Thus sodium borate (NaHgBOg) is formed by repla- 
 cing one hydrogen. The hydrogen contained in this salt 
 is combined with oxygen in the form of water, and can 
 be driven off by heat (H3BO3-H3O.) 
 
 Meta-Boracic Acid, HBOg (H3BO3 — H3O). 
 
Inorganic Chemistry. 163 
 
 Borax or fused sodium borate (NagB^O,) is a combi- 
 nation of the sodium meta-borate (NaBOg), and boric 
 oxide BgOg. Thus: 
 
 Dehydrated sod. borate. Boric oxide. Borax. 
 
 aNaBOg + B^Oa = NagB^O,. 
 
 Borax and boric acid are antiseptic and used in preserv- 
 ing articles. 
 
CHAPTER IX. 
 PHOSPHORUS. 
 
 Symbol'?. Atomic weight ^i. Equivalence l-lll-Y . 
 
 History. Phosphorus was discovered by Brant in 1669, 
 from urine. 
 
 Occurrence. Phosphorus does not occur free in nature, 
 but usually in combination with calcium, magnesium, and 
 lead. 
 
 Preparation. Burnt bone is allowed to macerate in sul- 
 phuric acid (H2SO4) for some hours. This extracts from 
 the bones phosphorus in the form of acid calcium phos- 
 phate, CaH4(P04)3, which remains in solution, and is 
 poured off from the remainder of the mixture and evap- 
 orated to a syrupy consistency, being converted into the 
 meta-phosphate Ca(P03)3. This is next mixed with char- 
 coal and heated to redness — the phosphorus distils over 
 and is condensed. Thus : 
 
 Calc. meta-phosphate. Carbon Calc. ortho-phosphate. 
 
 SCaCPOs)^ + loC = Ca^CPO^);, 
 
 Carbonyl. Phosphorus. 
 
 + loCO + P4. 
 Properties. 
 
 a. Physical. Phosphorus exists in two allotropic forms. 
 In its usual form it is a colorless, transparent, and waxy 
 substance with a peculiar odor. It is insoluble in water, 
 but soluble in ether, alcohol, oils, and carbon di-sulphide. 
 
 b. Chemical. It oxidizes readily and burns in the air, 
 hence must be kept under water. Owing to slow combus- 
 
 164 
 
Inorgcinic Chemistry. 165 
 
 tion it is luminous in the dark and forms phosphorous 
 oxide (P3O3). By rapid combustion it forms phosphoric 
 oxide (PgOg). By heating this form of phosphorus to 
 25o°C. it is converted into the other allotropic state. 
 
 This form of phosphorus is a chocolate-red powder in- 
 soluble in ordinary solvents, does not oxidize readily in 
 the air, has no odor, is not poisonous, does not burn easily, 
 and will not shine in the dark. 
 
 Uses. Phosphorus is used principally in matches — both 
 forms of phosphorus being employed. 
 
 Compounds. 
 
 1. OF PHOSPHORUS AND HYDROGEN. 
 
 HYDROGEN PHOSPHIDE ORPHOSPHINE. . 
 
 H 
 
 I 
 Formula: H„P, orP — H 
 
 I 
 H 
 
 Preparation. Phosphine is usually prepared by boiling 
 phosphorus with a solution of caustic potash (KOH). 
 Thus: 
 
 Phosphorus. Potass, hydrate. -Water. Pot. hypophosphite. Phosphine. 
 
 4P + 3KOH + 3H2O = 3KH,P0, + PH3. 
 Properties. Phosphine is a colorless gas with a garlic- 
 like odor, slightly soluble in water, and burns with a 
 brilliant flame. 
 
 2. OF PHOSPHORUS AND OXYGEN. 
 
 As phosphorus has an equivalence of I, III, and V, by its 
 union with oxygen three oxides are formed. Thus : 
 
 P 
 
 >0 or PgO, hypophosphorous oxide. 
 P 
 
66 
 
 
 
 Inorganic Chemistry. 
 
 O 
 
 
 
 
 II 
 P 
 
 
 
 
 >Oor 
 P 
 
 P303 
 
 , phosphorous oxide. 
 
 X 
 
 II 
 
 O 
 
 o 
 
 
 
 o. 
 
 II 
 =p 
 
 
 
 0= 
 
 >0 
 
 =p 
 
 orPj 
 
 jOj, phosphoric oxide. 
 
 o 
 
 There are three well-known acids formed from the ic 
 oxide by substituting two hydroxyls for i, 2, and 3 of the 
 oxygen atoms, or, in other words, by adding 1,2, and 3 
 molecules of water. Thus : 
 
 P3O5 -f" HgO = 2HP0g, called meta-phosphoric acid. 
 
 P2O5 + 2H20= H4P3O,, called pyro-phosphoric 
 acid. 
 
 PgOg + 3H2O = 2H3PO4, called ortho-phosphoric 
 acid. 
 
 These terms are applied for convenience to the acids of 
 P. without relation to the usual meaning of the words 
 ortho and pyro. 
 
 PHOSPHORIC OXIDE. 
 
 Formula: PgOj. 
 
 Preparation. Phosphoric oxide is prepared by the 
 rapid combustion of phosphorus in the air. P^ -|- O5 = 
 P^Og. 
 
 Properties. It is a white, amorphous powder, attracting 
 moisture from the air and dissolving in water with a hiss- 
 ing noise, forming ortho-phosphoric acid (H 3 PO^). 
 
Inorganic Chemistry. 167 
 
 ORTHO-PHOSPHORIC ACID. 
 Formula: H3PO4. 
 
 Preparation. Ortho-phosphoric acid is prepared by- 
 adding boiling water to phosphoric oxide (PgOg). Thus: 
 
 Phosphoric oxide. Water. Ortho-phosphoric acid. 
 P3O5 + 3H2O = 2H3PO,, 
 
 or it can be prepared by the oxidation of phosphorus with 
 nitric acid. 
 
 Properties. Phosphoric acid is a clear, syrupy liquid 
 with an acid reaction. 
 
 As there are three hydrogens that can be replaced by 
 basic elements, it follows that there are three varieties of 
 salts that can be formed, viz.: acid, normal, and double 
 (see Theoretical Chemistry), and that the salts may be 
 mono-, di-, or tri- basic. 
 
 Thus calcium is a diad and will take the place of two 
 hydrogens, hence C^f/^^^f^O^^ is mono-calcic-ortho- 
 phosphate or super-phosphate and an acid salt. Again, 
 di-calcic-ortho-phosphate must be an acid salt with a for- 
 mula CagH2(P04)2, for to saturate two atoms of calcium 
 it will take four atoms of hydrogen, and as there are only 
 three in the acid two molecules must be taken, or H5(P0- 
 4)3, to combine with the calcium. Again, tri-calcic-ortho- 
 phosphate, or bone phosphate, is Ca3(P04)g and a normal 
 salt. 
 
 Ammonium - magnesium - ortho - phosphate (NH4) M 
 PO4 is a double salt of ortho-phosphoric acid, 
 
 PYRO-PHOSPHORIC ACID. 
 
 Formula: H^PgO,. 
 
 Preparation. This acid is prepared by heating phos- 
 phoric acid, H3PO4, to 2i5°C., and thus driving off a mole- 
 cule of water. Thus : 
 
 ■ ^^J.A. \M 
 
1 68 Inorganic Chemistry. 
 
 Ortho-phosphoric acid. Water. Pyro-phosphoric acid. 
 2H3PO4 — H3O = H4P2O,. 
 
 Properties. Pyro-phosphoric acid is a clear fluid sub- 
 stance with an acid reaction. By substituting for the 
 hydrogens in this acid, basic elements, different kinds of 
 pyro salt are formed, as are ortho salts from ortho-phos- 
 phoric acid. Thus: Na^PgO, is normal, and NagHgP^O, 
 acid, sodium pyro-phosphate. 
 
 META-PHOSPHORIC ACID. 
 
 Formula : H P O g . 
 
 Preparation. Meta-phosphoric acid is prepared by heat- 
 ing ortho-phosphoric acid to redness, thus driving off a 
 molecule of water. 
 
 Ortho-phosphoric acid. Water. Meta-phosphoric acid. 
 
 H3PO4 — HgO = HPO3, 
 or by dissolving phosphoric oxide (PgOg) in water. Thus : 
 
 Phosphoric oxide. Water. Meta-phosphoric acid. 
 
 P.Os -f H3O = 2HPO3. 
 
 Properties : 
 
 This acid is a transparent ice-like solid, soluble in water 
 and with an acid reaction. As it contains but one hydro- 
 gen, it forms but one class of salts — normal. 
 
 PHOSPHOROUS OXIDE. 
 
 Formula : P 3 O 3 . 
 
 Preparation. It is formed by the incomplete oxidation 
 of phosphorus. 
 
 Properties. It is a volatile, white, flaky solid, with a 
 peculiar odor. It dissolves in water with a hissing noise. 
 
Inorganic Chemistry. • ' 169 
 
 HYPOPHOSPHITES. 
 
 By adding three molecules of water to hypophosphorous 
 oxide there is formed theoretically hypophosphorous 
 
 acid HjPOg. 
 
 (PjO + sHgO = 2H3PO2.) , 
 By substituting basic elements in place of the hydrogens, 
 salts are formed called hypophosphites — used in medicine. 
 
CHAPTER X. 
 
 ALKALINE METALS. 
 
 Metals are distinguished from the non-metallic elements 
 by their lustre, ductility, malleability, and tenacity ; by 
 being good conductors of heat and electricity, and electro- 
 positive. They form in union with themselves alloys, but 
 when they unite with non-metals they lose all metallic 
 properties and form bases. 
 
 Alkaline metals have the property of turning litmus 
 blue and turmeric brown. They saponify fats, neutralize 
 acids, cauterize the skin, and are six in number, lithium, 
 potassium, sodium, ammonium, caesium, and rubidium. 
 
 SODIUM. 
 
 Symbol Na. Atomic weight 23. Equivalence I. 
 
 Occurrence. Sodium is a very abundant element in 
 nature. It occurs largely as a chloride in rock salt and 
 sea water. It also occurs as a carbonate, borate, silicate, 
 etc. 
 
 Preparation. Sodium is prepared by reducing its oxide 
 (NagO) at a white heat with carbon. Thus: 
 
 Sodium oxide. Carbon. Sodium. Carb. monoxide. 
 
 NagO + 2C = Na + 2CO. 
 
 Properties. Sodium is a silvery-white soft metal. It 
 decomposes water and oxidizes readily in the air, hence 
 must be kept in some such solution as naphtha. By appli- 
 
 170 
 
Inorganic Chemistry. 171 
 
 cation of heat, sodium burns'with a yellow flame, forming 
 sodium oxide Na^O. 
 
 Uses. Sodium is used in metallurgy as a reducing 
 agent. 
 
 Compounds. Sodium chloride or common " salt " (NaCl) 
 is obtained by evaporating saline waters or by mining it 
 in the form of rock salt. Sodium hydrate or " caustic 
 soda" (NaOH) is prepared by the decomposition of water 
 by metallic sodium. Thus : 
 
 Water. Sodium. Sod. hydrate. Hydrogen. 
 
 HgO + Na = NaOH + H, 
 or by the action of calcium hydrate Ca(OH)g upon sodium 
 carbonate, NagCOj. Thus: 
 
 Calcic hydrate Sod. carbonate. Sod. hydrate. Calc. carbonate, 
 
 Ca(0H)2 + NagCOg = 2NaOH + CaCOj. 
 
 It is a very deliquescent white salt, coagulating albu- 
 men and having caustic properties. Sodium nitrate or 
 "soda saltpetre " (NaNOg) is a white salt very soluble in 
 water and used in medicine. 
 
 Sodium carbonate or "soda," NagCOj, was formerly 
 obtained from the ashes of sea-weed, but is now obtained 
 by the famous Leblanc soda process as represented in the 
 following formulae. Thus : 
 
 x. Sodium chloride. Sulph. acid. Sod. sulph. Hydrochloric acid. 
 
 2NaCl + H3SO4 = Na3S04 + 2HCI. 
 
 s. Sodium sulphate. Calcic carb. Carbon. Sodium carbonate. 
 
 NagSO^ + 2CaC03 -f 2C = Na^COg. 
 
 Carbonic oxide. Calcic sulphide and oxide. 
 
 + SCOg + CaS, CaO. 
 
 " Baking powder " is acid super- or bi-carbonate of soda 
 (NaHCOj). 
 
 Sodium sulphate (Na2S04). Its preparation is repre- 
 sented in the first formula of Leblanc's soda process. 
 
172 Inorganic Chemistry. 
 
 The acid sodium sulphate (NaHS04) is prepared by- 
 adding sulphuric acid to the normal salt (NagSO^). All 
 the sodium salts are soluble in water. 
 
 POTASSIUM. 
 
 Symbol K. Atomic weight 39. Equivalence I. 
 
 Occurrence. Potassium always occurs in combination, 
 usually as a chloride, nitrate, or sulphate. It occurs in all 
 vegetable tissues. 
 
 Preparation. It is prepared in a manner analogous to 
 that of obtaining sodium, but is a more dangerous pro- 
 cess, as the metal is apt to combine with carbonic monox- 
 ide (CO), which forms an explosive mixture. 
 
 Properties. Potassium is a soft bluish white metal, and 
 has properties similar to those of sonium. 
 
 Compounds. Potassium chloride (KCl) occurs native and 
 is prepared from sea water. It is much like sodium 
 chloride (NaCl). 
 
 Potassium bromide (KBr) and iodide (KI) are prepared 
 by the direct action of bromine and iodine upon potas- 
 sium hydrate (KOH). 
 
 Both salts are used extensively in medicine. Potas- 
 sium hydrate (KOH) or " caustic potash " is prepared in 
 sticks, which are very deliquescent and have caustic prop- 
 erties coagulating albumen. 
 
 Potassium chlorate (KC103)is used extensively in the 
 preparation of oxygen. 
 
 Potassium nitrate or "nitre" (KNO3) occurs native 
 upon the surface of soils in Bengal. Potassium sulphate 
 (K3SO4) is used extensively in the manufacture of gun- 
 powder (3C + S + 2KNOs). 
 
 Gun powder. C. dioxide. K. sulphide. 
 
 3C + S + 2KNO3 = 3CO, -f K^S-fNa 
 
Inorganic Chemistry. 173 
 
 Potassium carbonate, " potash," or " pearlash " (KgCOg) 
 is prepared by evaporating the teachings of wood ashes. 
 
 Potassium bicarbonate, called acid super- or bi-carbo- 
 nate of potash, is used extensively in bread-making under 
 the name of " saleratus." 
 
 All potassium salts are soluble in water and have an 
 alkaline reaction. 
 
 AMMONIUM. 
 
 Symbol NH4. Molecular weight 18. Equivalence I. 
 
 Properties. Ammonium is not an element but is really 
 a compound radical with an equivalence of I. It acts as 
 a basic element with an equivalence of I replacing the 
 hydrogens in acids to form salts. 
 
 Ammonium has never been isolated except as an amal- 
 gam (NH4)3Hg, which is prepared thus: 
 
 Ammon. chloride. Sod. amalg. Sod. chlor, Ammon. amalg. 
 
 2(NH4)C1 -f Na^Hg = 2NaCl + (NH,)Hg. 
 
 Compounds. Ammonium chloride or " sal ammoniac," 
 (NH4)C1, is obtained by heating the ammoniacal liquors 
 from coal distillation with hydrochloric acid (HCl). 
 
 All the ammonium salts, as the carbonate, (NH4)gC03, 
 nitrate, (NH4)N03 and sulphate (NH4,)2S04 are soluble 
 in water, alkaline in reaction, and volatile. 
 
 Aqua Ammonia is ammonia (NHg), dissolved in water. 
 Thus : 
 
 NH + 3H3O = NH4OH. It has all the properties of 
 caustic soda or potash, but will not saponify fats and is 
 volatile. 
 
 LITHIUM. 
 
 Symbol lA. Atomic weight 7. Equivalence I. 
 Occurrence. Lithium occurs usually as a chloride in 
 
1/4 Inorganic Chemistry. 
 
 mineral and sea waters. It is also found sparingly in 
 some minerals. 
 
 Preparation. It is best prepared from the chloride of 
 lithium, LiCl, by electrolysis. 
 
 Properties. Lithium is a soft, light, and silvery-white 
 metal. It tarnishes in the air, decomposes water, and 
 burns with a white flame at high temperatures. 
 
 Compounds. Many of the lithium compounds are vola- 
 tile and burn with a brilliant crimson flame. All of its 
 salts are soluble in water, but the carbonate of lithium, 
 X^igCOj, sparingly so. All of the watery solutions of 
 lithium salts have an alkaline reaction, and many are used 
 in medicine. 
 
CHAPTER XI. 
 
 ALKALINE EARTHS. 
 MAGNESIUM, STRONTIUM, BARIUM, CALCIUM. 
 
 MAGNESIUM. 
 
 Symbol Mg. Atomic weight 24. Equivalence II. 
 
 Occurrence. Magnesium is always found in combina- 
 tion, usually as a hydrate, carbonate, silicate, borate, or 
 chloride. 
 
 Preparation. It is best prepared by heating magnesium 
 chloride (MgClg) with sodium. Thus : 
 
 Mag. chloride. Sodium. Magnesium, Sod. chloride. 
 
 MgClg -f- 2Na = Mg + 2NaCl. 
 
 Properties. Magnesium is a silvery-white metal, malle- 
 able and ductile. It oxidizes in moist atmospheres, is 
 volatile, and burns with a brilliant white flame at high 
 temperatures. 
 
 Compounds. Magnesium has marked basic properties, 
 replacing hydrogen in acids to form salts. The oxide of 
 magnesium or " magnesia " (MgO) occurs in nature, and is 
 also produced by the combustion of magnesium. The 
 sulphate of magnesium or "Epsom salts" (MgS04) is 
 very soluble in water, and is used in medicine. The car- 
 bonate of magnesia or, " magnesia alba " (MgCOg) is 
 produced by the action of sodium carbonate (NagCOg) 
 upon magnesium sulphate (MgS04). Thus: 
 
 175 
 
176 Inorganic Chemistry, 
 
 Mag. sulphate. Sod. carbonate. Mag., carbonate. Sod. sulphate. 
 
 MgSO^ + Na^COg = MgCOj + NagSO^. 
 
 It is a white, light powder, insoluble in water. The 
 hydrate of magnesium, Mg(0H)2, occurs free in nature, 
 and is slightly soluble in water, and has an alkaline 
 reaction. 
 
 STRONTIUM. 
 
 Symbol Sr. Atomic weight 87.6. Equivalence II. 
 
 Occurrence. Strontium occurs in nature as a sulphate 
 and carbonate. 
 
 Preparation. It is prepared by electrolysis from the 
 chloride of strontium (SrClg). 
 
 Properties. Strontium is a soft yellow metal. It is 
 fusible at a red heat, and burns with a brilliant flame, 
 forming strontium oxide (SrO). 
 
 Compounds. The native salts of strontium, the carbo- 
 nate (SrCOg) and the sulphate (SrS04), are insoluble in 
 water and used principally in the preparation of the two 
 soluble salts, the nitrate of strontium ,Sr-(N03)2, and the 
 chloride of strontium (Sr-Clg). 
 
 These salts are used in the arts, and in the preparation 
 of red fire. 
 
 BARIUM. 
 
 Symbol's^ Atomic weight 137. Equivalence W. 
 
 Occurrence. Barium occurs in nature as a sulphate and 
 carbonate. 
 
 Preparation. It is prepared from the chloride of bari- 
 um (BaClg) by electrolysis. 
 
 Properties. It is a yellowish malleable metal, rapidly 
 decomposing water when brought in contact with it. 
 
 Compounds. There are two oxides of barium — the bari- 
 um dioxide (BaOg), which is used in the preparation of 
 
Inorganic Chemistry. 177 
 
 hydrogen dioxide (HgOg), and the barium oxide (BaO). 
 The natural salts of barium are the carbonate (BaCOj) 
 and the sulphate (BaS04), both insoluble in water. The 
 sulphate is used as a paint, and also to adulterate white 
 lead. Both salts are used in the preparation of the solu- 
 ble barium salts, the nitrate of barium, Ba(N03)2, and 
 the chloride (BaClg). 
 
 These compounds are used in making green fire. 
 
 CALCIUM. 
 
 Symbol Ca. Atomic weight 4.0. Equivalence 11. 
 
 Occurrence. Calcium is one of the most abundant ele- 
 ments in nature. It occurs as a carbonate in chalk, lime- 
 stone, and marble ; as a sulphate in gypsum ; and as a 
 phosphate, silicate, etc., in bones, minerals, and vegetables. 
 
 Preparation. It is prepared from the chloride of calci- 
 um (CaCl^) by electrolysis or by fusing it, or the iodide of 
 calcium (Calg), with sodium. Thus : 
 
 Calcium chloride. Sodium. Sod. chloride. Calcium. 
 
 CaClg -f 2Na = 2NaCl + Ca. 
 
 Properties. Calcium is a brilliant yellow metal, mallea- 
 ble and ductile. It oxidizes and burns brightly at a red 
 heat. 
 
 Compounds. One of the principal compounds of calcium 
 is the oxide (CaO) or " lime." It is prepared by driving 
 off carbonic oxide (COg) from the carbonate of calcium 
 (CaCOg) by means of heat. Thus : 
 
 Calcium carbonate. Calcium oxide. Carbon oxide. 
 
 CaCOs = CaO + CO3 
 It is a hard, white solid, uniting directly with water to 
 form calcic hydrate Ca(0H)2. Calcium hydrate is slightly 
 soluble in water — the solution having an alkaline reaction, 
 and commonly called " lime water." 
 
178 Inorganic Chemistry. 
 
 Calcium sulphate (CaS04) or " gypsum " occurs free in 
 nature. It contains water of crystallization, which can be 
 driven off at a temperature of 250° C, forming what is 
 commonly called plaster of Paris, or cement. 
 
 It is a dry powder, but quickly hardens or sets upon 
 the application of water. 
 
 " Mortar " is calcium hydrate, Ca(0H)3, and sand. Its 
 hardening properties are chiefly due to its combination 
 with carbonic oxide (COg), forming calcic carbonate 
 (Ca-COg). Thus : 
 
 Calcic hydrate. Carbonic oxide. Calcic carbonate. Water, 
 
 Ca(0H)2 + CO2 = CaCOg + H3O 
 The water thus produced by this combination evapo- 
 rates from the walls of new buildings, making them very 
 damp for a long time. 
 
 Barium, strontium, and calcium are called alkaline earth 
 metals. These carbonates are insoluble in water, but their 
 hydroxides are alkaline and soluble. 
 
CHAPTER XII. 
 
 TIN, ZINC, CADMIUM. 
 
 TIN (Stannum). 
 
 Symbol Sn. Atomic weight Ii8. Equivalence II and IV. 
 
 Occurrence. Tin , occurs principally as stannic oxide 
 (SnOg), called cassiterite. 
 
 Preparation. This stannic oxide is roasted and then 
 melted with charcoal, which combines with the oxygen, 
 leaving the metallic tin. 
 
 Properties. Tin is a soft white metal, very malleable 
 and ductile. It has a peculiar odor, crackles (tin cry) 
 when broken, and is a good conductor of heat and elec- 
 tricity. It is not volatile, but burns at a high tempera- 
 ture, forming stannic oxide (SnO^). 
 
 Uses. Tin is used in making foil and alloys. 
 
 Compounds. 
 
 I. OF TIN AND CHLORINE. 
 
 As tin has an equivalence of two or four it forms by its 
 union with chlorine two compounds. Thus : 
 
 CI 
 Sn< 
 
 CI or SnClg, stannous chloride. 
 
 CI 
 
 CI — Sn — CI or SnCl4, stannic chloride. 
 
 CI 
 
 179 
 
i8o Inorganic Chemistry. 
 
 STANNOUS CHLORIDE. 
 Formula: SnCl^. 
 
 Preparation. It is prepared by the action of mercurous 
 chloride, HggCl^, on tin filings. Thus : 
 
 Mercurous chloride. Tin. Mercury. Stannous chloride. 
 
 Hg.Clg + Sn = Hgg + SnClg. 
 Properties. This is a grayish-white solid, soluble in 
 water. Upon evaporating its aqueous solution, crystals, 
 known as " tin salt," are formed, which are used in dyeing. 
 
 STANNIC CHLORIDE. 
 Formula: SnC^. 
 
 Preparation. It is prepared by distilling mercuric chlo- 
 ride (HgClg) with tin. Thus : 
 
 Mercuric chloride. Tin. Mercury. Stannic chloride. 
 
 2HgCl3 + Sn = Hgg + SnCl^. 
 Properties. It is a colorless fuming liquid uniting 
 directly with alkaline chlorides to form compounds. 
 It is used in dyeing. 
 
 2. OF TIN AND OXYGEN. 
 As there are two compounds of tin with chlorine, so 
 two are formed by the union of tin with oxygen. 
 
 STANNOUS OXIDE. 
 
 Formula : SnO. 
 
 Properties. This oxide is a black powder which absorbs 
 oxygen from the air, forming stannic oxide (SnOg). 
 
 STANNIC OXIDE. 
 
 Formula: SnOg. 
 
 Preparation. This occurs free in nature but mixed with 
 impurities. It is best prepared by burning tin in presence 
 of oxygen. 
 
Inorganic Chemistry. i8l 
 
 Properties. Thus prepared it is a very hard white pow- 
 der, insoluble in all acids save hydrofluoric (HF). It is 
 used for polishing glass under the name of " putty 
 powder." 
 
 By the addition of a molecule of water to each oxide 
 two corresponding acids are formed, called stannous 
 (HgSnOg) and stannic (H^gSnOg) acids. Stannite and 
 stannate salts are formed from the acids by substituting 
 basic elements for the hydrogens of each. 
 
 3. OF TIN AND SULPHUR. 
 
 The principal sulphide of tin is the stannic (SnS^). It 
 is a golden-yellow powder known as " mosaic gold." 
 
 ZINC. 
 
 Symbol Zn. Atomic weight 6t). Equivalence 1\. 
 
 Occurrence. It occurs in nature as zinc ore in combina- 
 tion with oxygen, silica, carbon, sulphur, etc. 
 
 Preparation. It is prepared by first roasting the ore and 
 then distilling with charcoal. The oxygen is removed by 
 combining with the carbon, and the zinc volatilizing, dis- 
 tils over and is condensed. 
 
 Properties. Tatxc is a bluish-white, brittle metal. It is 
 both ductile and malleable, oxidizes readily. It volatil- 
 izes and burns at high temperatures, forming zinc oxide. 
 (ZnO). 
 
 Uses. Zinc is so readily acted upon by acids that it 
 forms the positive element in nearly all voltaic batteries. 
 
 It is also largely used in making alloys — with copper 
 forming brass ; with tin and copper, bronze, etc. Iron 
 coated with zinc is called galvanized iron. 
 
I82 
 
 Compounds. 
 
 Inorganic Chemistry. 
 
 I. OF ZINC AND OXYGEN. 
 ZINC OXIDE. 
 
 Formula: ZnO. 
 
 Preparation. It occurs as native zinc ore, but is best 
 prepared by the combustion of zinc in presence of oxygen. 
 
 Properties. Thus prepared, zinc oxide is a white pow- 
 der, insoluble in water, and used chiefly as a pigment. By 
 the addition of one molecule of water, zinc hydrate, Zn 
 (0H)2, is formed. It has strong basic properties, and 
 when acted upon by acids forms zinc salts, as zinc sulphate 
 (ZnS04) and zinc carbonate (ZnCOj). 
 
 2. ZINC AND CHLORINE. 
 ZINC CHLORIDE. 
 
 Formula: ZnClg. 
 
 Preparation. Zinc chloride is prepared by dissolving 
 zinc in hydrochloric acid (HCl), and evaporating the solu- 
 tion to dryness. 
 
 Properties. It is a white crystalline solid, volatile at 
 high temperatures. It has very strong atttactions for 
 water, and hence is a powerful caustic and dehydrating 
 agent. The sulphate and chloride are both disinfectants. 
 
 CADMIUM. 
 
 Symbol Q,^. Atomic weight 112. Equivalence W. 
 
 Occurrence. It usually occurs in compounds with zinc 
 ores as a sulphide (CdS). 
 
 Preparation. As cadmium is more volatile than zinc, it 
 is prepared from the distillation of zinc ores, which con- 
 tain it by catching the first products of distillation. 
 
Inorganic Chemistry. 183 
 
 Properties. Cadmium closely resembles zinc, but is 
 more volatile, is whiter and heavier. It is less easily- 
 attacked by acids. 
 
 Compounds : 
 
 Its compounds also closely resemble those of zinc. The 
 sulphide (CdS) has a bright yellow color, and is used 
 largely as a pigment. 
 
CHAPTER XIII. 
 LEAD, COPPER, MERCURY. 
 
 LEAD (Plumbum). 
 
 Symbol Pb. Atomic weight 207. Equivalence II. and 
 IV. 
 
 Occurrence. Lead occurs in nature principally as a sul- 
 phide, but also as a carbonate, arseniate, phosphate, etc. 
 
 Preparation. It is usually prepared from the sulphide 
 (PbS) by first roasting the ore in presence of oxygen, thus 
 forming an oxide and sulphate of lead. These compounds 
 react upon the remaining unchanged sulphide, producing 
 sulphurous oxide (SOg) and metallic lead. Thus : 
 
 Lead oxide. Lead sulphide. Sulph. oxide. Lead. 
 
 2PbO + PbS = SO2 + 3Pb. 
 
 Lead sulphate. Lead sulphide. Sulph. oxide. Lead. 
 
 PbSO^ + PbS = 2S0a + 3Pb. 
 
 Properties. Lead is a soft, malleable, and bluish-white 
 metal. It tarnishes readily in the air, and is easily fusible. 
 
 Water dissolves lead, especially if it contains organic 
 matter or nitrate-s, depositing it as a carbonate (PbCOg). 
 
 Acetic, carbonic, and nitric acids dissolve it readily, but 
 other acids scarcely attack it. It acts as a constitutional 
 poison when taken into the human system. 
 
 Uses. Lead is used in forming alloys — with arsenic it 
 forms shot; with antimony and tin, type-metal; with tin, 
 solder, etc. It is also used largely in the manufacture of 
 water-pipes. 
 
 184 
 
Inorganic Chemistry. 185 
 
 Compounds. Lead usually acts as a basic element with 
 an equivalence of II., and as such replaces the hydrogens 
 in acids to form salts. Among the most important of 
 these salts are the sulphate(PbS03), the nitrate, Pb(N0g)2, 
 the carbonate (PbCOg), and the acetate, PbCCgHgOa)^, 
 of lead. 
 
 The plumbic acetate is soluble in water, has a sweet 
 astringent taste, and is commonly called " sugar of lead." 
 There are two oxides of lead : the plumbic oxide (PbO) 
 or " litharge," which occurs free in nature, and is prepared 
 chemically by melting lead in a current of air ; and 
 plumbic dioxide (PbOg). Red lead is a compound of the 
 two oxides (2PbO + PbOg). 
 
 Chrome yellow is chromate of lead (PbCrO^). Many of 
 the lead salts are used as pigments. 
 
 COPPER (Cuprum). 
 
 Symbol Cn. Atomic weight dT^.A^. Equivalence W. 
 
 Occurrence. Copper occurs free in nature, but usually 
 in combination with sulphur and iron (pyrites), carbon, 
 oxygen, etc. 
 
 Preparation. From its combination with carbon and 
 oxygen metallic copper is prepared by reducing the ores 
 with carbon and silica in a blast furnace. Copper is usu- 
 ally prepared from the pyrites by repeatedly roasting the 
 ore, thus converting a portion of the copper and all of the 
 iron into an oxide. This mass is then fused with silica, 
 forming a slag containing the iron, while the copper in the 
 unchanged copper ore remains as a sulphide, ^y again 
 roasting this sulphide the copper oxide now produced 
 reacts upon the unchanged sulphide, forming metallic 
 copper and sulphurous oxide. Thus : 
 
i86 Inorganic Chemistry. 
 
 Copper sulphide. Copper oxide. Sulpli. oxide. Copper. 
 
 CuS + 2CuO = SOg + 3Cu. 
 
 If any of the oxide remains in the molten mass, it is 
 reduced by " poling " — stirring with a green stick. 
 
 Properties. Copper is a reddish-colored metal, softer 
 than iron. It is malleable, ductile, and tenacious ; a good 
 conductor of heat and electricity. It oxidizes slowly in 
 the air at ordinary temperatures, and rapidly upon the 
 application of heat. 
 
 It is readily dissolved by nitric acid, and slowly in weak 
 alkaline acid, and saline solutions, forming poisonous com- 
 pounds. Chlorine and sulphur attack it readily, forming 
 chloride and sulphide of copper. 
 
 Uses. Copper is used generally in the arts, and for 
 making alloys, as german silver, bronze, etc. 
 
 Compounds. Copper is a diad, but unites with other 
 elements to form compounds either with the use of one 
 or two atoms. By the use of one atom (Cu) it forms ic 
 compounds, and by the use of two atoms (Cug), ous com- 
 pounds. Thus there are two oxides of copper : cupric or 
 black oxide, CuO or Cu, Cu = O, occurring in nature and 
 always produced by the conibustion of copper ; and cuprous 
 
 Cu 
 or red oxide, Cu 2 O, or | >0, also occurring free in nature, 
 
 Cu 
 and produced by the reduction of copper solutions by 
 grape sugar in the presence of alkalies. In the same way 
 there are two chlorides of copper, the cupric (CuClg) and 
 the cuprous (CugClg). Both sulphides of copper (CuS 
 and CugS) occur native. 
 
 Ous and ic salts of copper are formed by replacing the 
 hydrogens in acids by either Cug or Cu. The ic salts are 
 the most stable. Many of the copper compounds are 
 brilliantly colored and used as pigments. 
 
Inorganic Chemistry. 187 
 
 MERCURY (Hydrargyrum). 
 
 Symbol Hg. Atomic weight 200. Equivalence II. 
 
 Occurrence. Mercury occurs free in small quantities, 
 but it is usually combined with sulphur, forming cinnabar. 
 
 Preparation. Mercury is prepared from cinnabar by 
 roasting the ore, thus volatilizing the metal, which is after- 
 ward condensed. 
 
 Properties. Mercury at ordinary temperatures is a sil- 
 very-white fluid metal. It freezes at-40° C, vaporizes at 
 15° C, and boils at 350° C. It does not oxidize at ordi- 
 nary temperatures. Chlorine, sulphur, and nitric acid 
 (HNOg) attack it readily, but other acids do not. 
 
 Uses. Mercury is used in the manufacture of thermom- 
 eters and barometers. Its alloys are called amalgams. 
 
 Compounds. Mercury, like copper, is a diad, and unites 
 with other elements either by the use of one or two 
 atoms. Its compounds formed by the use of one atom 
 (Hg) are called mercurzi;:, while those formed by the use 
 of two atoms (Hgg) are called mercur^MJ. 
 
 There are two important chlorides of mercury — the mer- 
 curic chloride HgClg, and the mercurous chloride HggClg. 
 
 CI 
 Mercuric chloride Hg < „. is prepared by heating mercu- 
 ric sulphate (HgSO^) with sodium chloride (NaCl). 
 Thus: 
 
 Mercuric sulphate. Sod. chloride. Sod. sulphate. Mercuric chloride. 
 
 HgSO^ + 2NaCl = Na2S04 + HgClg. 
 It is in the form of semi-transparent white crystals, sol- 
 uble in water and very poisonous. It is commonly called 
 bichloride of mercury, or " corrosive sublimate." 
 Hg-Cl 
 Mercurous chloride, | ' , is prepared by heating 
 Hg-Cl 
 
1 88 Inorganic Chemistry. 
 
 mercury with sodium chloride (NaCl), and mercuric sul- 
 phate (HgSO^). Thus : 
 
 Mercuric sulphate. Sod. chloride. Mercury sod. sulph. Mercurous chlo. 
 
 HgSO^ + 2NaCl + Hg=Na3S04 + Hg^Cla. 
 
 This forms a heavy amorphous powder, insoluble in 
 water and not very poisonous. It is commonly called 
 " calomel." 
 
 By heat and exposure to light it decomposes into mer- 
 cury and mercuric chloride (HgClj). 
 
 There are also two important iodides of mercury, the 
 mercuric iodide (Hgl^), and the mercurous iodide (Hggig). 
 
 Ous and ic salts of mercury are formed by replacing the 
 hydrogens of acids with Hgg or Hg. 
 
 Thus Hg(N0g)2 is mercuric nitrate, and Hg2(N03)g is 
 mercurous nitrate. 
 
 The ic compounds of mercury are more stable than the 
 ous. " White precipitate," so called, is a mercury amide, 
 HgClNH^ orCNHg)— Hg— CI. 
 
 " Turpeth mineral " (HgSO^ + 2HgO) is an emetic and 
 used in medicine. 
 
CHAPTER XIV. 
 
 PLATINUM, GOLD, SILVER. 
 
 PLATINUM. 
 
 Symbol Pt. Atomic weight 194.4. Equivalence II and 
 IV. 
 
 Occurrence. Platinum occurs native in round grains, 
 but is usually impure, containing gold, iron, copper, etc. 
 
 Preparation. It is best prepared by melting the impure 
 platinu,m with lead, which forms a nearly pure alloy of 
 platinic lead. This alloy is next heated in a current of 
 air. The lead melts, oxidizes, and is drawn off as slag, 
 leaving the pure platinum as a porous mass. 
 
 Properties. Platinum is a white, very malleable, and duc- 
 tile metal ; a good conductor of heat and electricity and 
 only fusible in an oxy-hydrogen blow-pipe flame. It is 
 not attacked by single acids, and is but slowly dissolved 
 in aqua-regia. 
 
 It does not tarnish. Finely divided or in the porous 
 form, platinum will absorb 800 times its own volume of 
 oxygen, and thus is an active oxidizing agent. 
 
 Compounds. As platinum has an equivalence of II or IV, 
 its compounds are either ous or ic. Thus there are two 
 chlorides of platinum — the platinous chloride (PtClj), and 
 the platinic chloride (PtCl4), which is formed by dissolv- 
 ing platinum in aqua-regia. 
 
 GOLD (Aurum). 
 Symbol Km,. Atomic weight Vjj . Equivalence I and III, 
 
 189 
 
iQO Inorganic Chemistry. 
 
 Occurrence. Gold is found pure in nature in quartz rock 
 or sand. 
 
 Preparation. The quartz rock containing the gold is 
 finely pulverized and treated with mercury, which forms 
 an amalgam with the gold. The mercury is distilled off, 
 leaving the pure gold. 
 
 Properties. Gold is a soft yellow metal, very ductile 
 and malleable ; does not tarnish in the air, and the only 
 acid attacking it is aqua-regia. 
 
 Uses. It is used in forming alloys and for coinage and 
 jewelry. 
 
 Compounds. Gold having an equivalence of I or III, forms 
 ous and ic compounds, the most important of which are 
 the chlorides, AuCl and AuClg. 
 
 Auric chloride (AuClg) is produced by dissolving gold 
 in aqua-regia. 
 
 The two oxides of gold are aurous oxide (AugO) and 
 auric oxide (AugOg). 
 
 SILVER (Argentum). 
 
 Symbol Ag. Atomic weight io8. Equivalence I and 
 III. 
 
 Occurrence. Silver is found free in nature and in com- 
 bination with sulphur, bromine, chlorine, etc. 
 
 Preparation. Silver is often found in combination with 
 lead, and is extracted from it in a manner analogous to 
 that of separating gold from its amalgam with lead. Sil- 
 ver is prepared from its sulphide by roasting the ore with 
 sodium chloride, thus forming chloride of silver. The 
 mass is then ground fine, and agitated with water and 
 scrap iron, which reduces the silver to the metallic state. 
 Mercury is then added, which takes up the silver and is 
 afterward distilled off, leaving the pure metal. 
 
Inorganic Chemistry. 191 
 
 Properties. Silver is a white metal, ductile, malleable, 
 tenacious, and harder than gold. It is the best con- 
 ductor of heat and electricity known. Does not tarnish 
 in air, but is easily attacked by chlorine, sulphur, nitric 
 acid, etc. 
 
 Uses. Silver is used for coinage, and also in making 
 jewelry and alloys. 
 
 Compounds. Silver usually acts as a monad. It has 
 strong basic properties, replacing the hydrogens in acids 
 to form salts. Thus we have nitrate of silver, AgNOj, 
 sulphate of silver, AggS04, chloride of silver, AgCl, and 
 are chemically all produced by dissolving silver in the 
 corresponding acid, viz. : nitric acid (HNO3), sulphuric 
 acid (H3SO4), and hydrochloric acid (HCl). 
 
 Many of the salts of silver, especially the nitrate, turn 
 black in presence of sunlight or organic matter, and there- 
 fore are used in photography and for hair dyes, indelible 
 inks, etc. 
 
CHAPTER XV. 
 
 CHROMIUM, MANGANESE, ALUMINUM. 
 
 CHROMIUM. 
 
 Symbol Cr. Atomic weight 52.5. Equivalence II and 
 (Cr,)VI. 
 
 History. This metal received the name of chromium 
 from the beautiful color of most of its compounds. 
 
 Occurrence. It occurs in nature combined with oxygen, 
 iron, and lead. 
 
 Preparation. It is prepared by heating the ore with 
 charcoal, and thus reducing the oxide. 
 
 Properties.' It is a steel-gray, infusible, and extremely 
 hard metal. 
 
 Burned in oxygen it forms chromic oxide (Crg03). 
 
 Compounds. As chromium has an equivalence of II or 
 VI it forms ous and ic compounds by its union with 
 chlorine, oxygen, etc. 
 
 But beside one atom of chromium uniting with other 
 atoms to form compounds, two atoms with an equivalence 
 of VI also unite with the same kind of atoms to form 
 different compounds. Thus there are two chromic oxides : 
 CrOg, called chromic tri-oxide, and CrgOg, chromic oxide. 
 
 CHROMIC TRI-OXIDE. 
 
 Formula: CrOg. 
 
 Properties. This oxide exists as crimson, needle-shaped 
 crystals. 
 
 Iq2 
 
Inorganic Chemistry. 193 
 
 It is very deliquescent and a powerful oxidizing agent. 
 By the addition of a molecule of water chromic acid 
 (H2Cr04) is formed. 
 
 CHROMIC ACID. 
 
 Formula : H g CrO 4 . 
 
 Properties. Chromic acid is a pinkish and corrosive 
 fluid. 
 
 By its evaporation it loses water, and crystals of chromic 
 tri-oxide CrOg. are formed. — , 
 
 Chromate salts are formed by replacing the hydrogens 
 in chromic acid by basic elements as sodium and potas- 
 sium, thus forming sodium chromate (Na3Cr04) and 
 potassium chromate (K2Cr04). 
 
 Bichromate salts, the most important of which is potas- 
 sium bichromate (KgCr^O,), are formed by replacing the 
 hydrogens in bichromic acid (HgCrgO,) with basic ele- 
 ments. This bichromic acid is theoretically formed by 
 adding a molecule of water to a double molecule of chro- 
 mic oxide, 2(CrOg). 
 
 CHROMIC OXIDE. 
 
 Formula: CrgOg. 
 
 Properties. As usually prepared, chromic oxide is an 
 amorphous, green powder. It is very hard and insoluble 
 in acids. It is used principally as an indelible ink for col- 
 oring bank-notes green. Theoretically, there is formed a 
 second chromic acid (H2Crg04) by the addition of water 
 to the oxide. 
 
 The salts formed from this acid by substituting basic 
 elements for the hydrogen are called chromites. Thus 
 there is ferrous chromite (FeCr3 04). 
 
 Chromium sometimes acts as a basic element, and will 
 
194 Inorganic Chemistry. 
 
 replace the hydrogen atoms in acids to form salts, as sul- 
 phate of chromium, Crg(S04)3. 
 
 MANGANESE. 
 
 Symbol Mn. Atomic weight 55. Equivalence II-IV-VI. 
 
 History. Manganese received its name from having at 
 first been mistaken for magnetic iron. 
 
 Occurrence. It occurs usually in nature as an oxide, 
 but also in combination with sulphur, iron, and arsenic. 
 
 Preparation. It is prepared by reduction of its oxide 
 (Mndg) with charcoal at a high temperature. 
 
 Properties. It is a grayish-white brittle metal, oxidizing 
 readily, forming manganese dioxide (MnOg). 
 
 Compounds. As manganese usually has an equivalence 
 of II or VI, by its union with chlorine, oxygen, etc., are 
 formed ous and ic compounds. 
 
 With an equivalence of VI, manganese may unite with 
 other elements either by the use of one or two atoms. 
 Thus manganic trioxide is MnOg, and manganic oxide is 
 MngOg. 
 
 There is still a third oxide of manganese, which is the 
 one occurring in nature and called manganic dioxide 
 (MnOg). Manganese in this compound has an equivalence 
 of IV. 
 
 Manganic dioxide gives off oxygen readily upon appli- 
 cation of heat, and hence is a good oxidizing agent. Theo- 
 retically acids and salts are produced from these oxides in 
 a manner analogous to the formation of similar acids and 
 salts from chromium oxides. But besides the ate and ite 
 salts thus produced, there are also permanganates formed 
 by substituting basic elements in place of the hydrogen in 
 permanganic acid (HgMoijOg). 
 ■ The most important of these salts is potassium perman- 
 
Inorganic Chemistry. 195 
 
 ganate (KgMngOg) which is a strongly oxidizing agent, and 
 therefore extensively used as a disinfectant. 
 
 Preparation. Manganese acting as a basic element 
 with an equivalence of II will replace the hydrogens 
 in acids, forming salts, as, for example, sulphate of man- 
 ganese (MnS04). 
 
 ALUMINUM. 
 
 Symbol h\. Atomic weight 27.5. Equivalence (Alg) VI. 
 
 Occurrence. Aluminum is the most abundant element 
 in nature next to oxygen and silicon, with which it is 
 usually found combined. The ruby and sapphire are ox- 
 ides of aluminum. Clay is a silicate of aluminum. 
 
 Preparation. Aluminum is prepared by passing the 
 vapor of aluminum chloride (AlgClg) over sodium. Thus: 
 
 Aiumin. chloride. Sodium. Sod. chloride. Aluminum. 
 
 AlgClg -\- 6Na = 6NaCl + Alg. 
 
 Properties. It is a very light bluish-white metal, malle- 
 able and ductile. It is not volatile, but will burn at a 
 high temperature, forming aluminum oxide (AlgOj). It 
 does not tarnish easily. 
 
 Uses. Aluminum is made into ornaments and used in 
 forming alloys. With sand and limestone it forms por- 
 celain. 
 
 Compounds. Aluminum has strong basic properties, 
 and unites by use of two atoms (Alg) with acids to form 
 salts. The sulphates Al3(S04)3 are the most important 
 compounds, as they are characteristic ingredients of all 
 alums. 
 
 An alum is a double sulphate plus water, and may be 
 expressed by the general formula Alg(S04)g + (x) + 
 HgO. The potash alum, Al2(S04)3 -f KgS04 + 24(H20), 
 is the most common. All alums are crystalline and styp- 
 tic, used principally in dyeing. 
 
CHAPTER XVI. 
 
 IRON, COBALT, NICKEL. 
 
 IRON (Ferrum). 
 
 Symbol Fe. Atomic weight 56. Equivalence II and 
 (Fe,) VI. 
 
 Occurrence. Pure iron occurs very sparingly in nature, 
 but in combination with oxygen (FegOg and Feg04), 
 silicon, sulphur, carbon, etc., it is abundant. 
 
 Preparation. Iron is usually prepared by heating to a 
 high temperature alternate layers of iron ore (ferric oxide, 
 FcgOg), charcoal, and limestone. The carbon removes 
 the oxygen. Thus : 
 
 Ferric oxide. Carbon. Iron. Carbon monoxide. 
 
 FcgOg 4- Cg = Fcg + 3CO, 
 while the limestone unites with the silica and other im- 
 purities to form a fusible silicate, which collecting above 
 the melted iron can be drawn off in form of " slag." 
 
 Properties. Iron thus prepared is run into molds, and 
 hence called " cast" or "pig" iron. 
 
 This is not pure iron but contains carbon, manganese, 
 sulphur, and other impurities. White pig-iron contains 
 more carbon than does the gray, and is therefore whiter 
 in color, harder, more brittle, and more fusible than the 
 gray. " Wrought " iron differs from pig-iron by being 
 comparatively pure. It is prepared from pig-iron by 
 burning out all its impurities by a process of oxidation 
 called " puddling." Wrought iron is bluish-gray in color, 
 fibrous in structure, and malleable. 
 
 196 
 
Inorganic Chemistry. 197 
 
 " Steel " is a form of iron containing from 2 to 4 
 per cent, carbon, and is prepared by heating wrought iron 
 to redness with charcoal. 
 
 Bessemer steel is a variety of iron containing beside the 
 carbon, manganese. It is prepared by naelting spiegeleisen 
 (pig-iron containing manganese and carbon) with wrought 
 iron. 
 
 Steel resembles wrought iron, but is granular in struc- 
 ture and more malleable and fusible. It also has the 
 peculiar property of becoming very hard and brittle when 
 heated and then suddenly cooled. 
 
 Compounds. As iron usually has an equivalence of II 
 or VI, by its union with other elements ous and ic com- 
 pounds are formed. In the ic compounds, however, iron 
 usually unites with other elements by the use of two 
 atoms (Fe^ with an equivalence of VI) instead of one. 
 Thus ferric carbonate is Feg(C03)3. 
 
 OF OXYGEN AND IRON. 
 
 There are three oxides of iron — ferrous oxide (FeO), 
 ferric oxide (FcgOg), and magnetic oxide (Feg04). 
 
 The ferric oxide is found in large quantities in nature, 
 and the magnetic oxide or loadstone, so named from its 
 magnetic properties, in small quantities. 
 
 COBALT. 
 
 Symbol Co. Atomic weight 59. Equivalence II and VI. 
 
 Occurrence. It occurs free in meteorites, but is usually 
 found in combination with arsenic. 
 
 Preparation. It is prepared by roasting the ore, thus 
 driving off the arsenic, which is volatile. The other 
 elements with which it is found are gotten rid of chemi- 
 cally, leaving the oxide of cobalt (CogOg), which is reduced 
 by heating with charcoal, thus leaving the pure cobalt. 
 
198 Inorganic Chemistry. 
 
 Properties. It has a steel-gray color, is magnetic, very- 
 hard, oxidizes at a red heat and tarnishes readily in a 
 moist atmosphere. 
 
 Compounds. Most of the cobalt compounds have brilliant 
 colors, and hence are used as pigments. As cobalt has 
 usually an equivalence of II or VI it forms ous and ic 
 compounds — the ous salts being the more important. In 
 most of the ic compounds cobalt unites with other ele- 
 ments by the use of two atoms (C03). It has strong basic 
 properties replacing the hydrogens in acids. 
 
 OF COBALT AND OXYGEN. 
 
 There are three oxides of cobalt analogous to those of 
 iron — cobaltous oxide (CoO). cobaltic tri- or sesqui-oxide 
 (C03O3), and cobaltic oxide (C03O4). 
 
 NICKEL. 
 
 Symbol Ni. Atomic weight 59. Equivalence II-IV-VI. 
 
 Occurrence. It occurs free in meteoric iron ore, but is 
 found usually in combination with arsenic, antimony, and 
 sulphur. 
 
 Preparation. It is prepared in a manner analogous to 
 the preparation of cobalt. 
 
 Properties. Nickel is a silver-white metal, ductile and 
 malleable. It does not tarnish in dry air, and is not easily 
 attacked by acids. 
 
 Uses. Nickel is used for plating and in making alloys. 
 German silver is an alloy of nickel, copper, and zinc. 
 
 Compounds. The equivalence, mode of union and com- 
 pounds of nickel are analogous to those of cobalt. The 
 ous salts are more important than the ic ; the nitrate, Ni- 
 (NOg)^, and sulphate (NiS04) are the two most important 
 soluble nickel salts. 
 
CHAPTER XVII. 
 
 ARSENIC. 
 
 Symbol As. Atomic weight '/t). Equivalence lll-'V . 
 
 History. Pure arsenic was first obtained by Schroeder, 
 in 1694. It had been known in combination for centuries. 
 
 Occurrence. Arsenic occurs free as native arsenic, but 
 usually in combination with iron, cobalt, nickel, and 
 sulphur. 
 
 Preparation. It is prepared by roasting arsenic ore, 
 thus driving off the volatile arsenic, which is condensed 
 as arsenious oxide, AsgOj. 
 
 This oxide is then reduced by heating it with charcoal. 
 Thus : 
 
 Arsenious oxide. Carbon. Arsenic. Carbon monoxide. 
 
 AS3O3 + 3C = Asg + 3CO. 
 
 Properties. Arsenic is a brittle solid with a metallic 
 lustre. It is volatilized by heat, giving off yellowish 
 fumes with a garlic-like odor. 
 
 At a high temperature arsenic burns with a blue flame 
 forming arsenious oxide (AsgOg). 
 
 Compounds. 
 
 I. OF ARSENIC AND HYDROGEN. 
 HYDROGEN ARSENIDE OR ARSINE. 
 H 
 
 Formula: HoAs, As — H. 
 
 I 
 H 
 
 199 
 
200 Inorganic Chemistry. 
 
 Preparation. Ars«tric is prepared by the action of sul- 
 phuric acid (H3SO4) upon zinc arsenide (AsgZnj). 
 Thus: 
 
 zinc arsenide. Sulph, acid. Zinc sulphate. Arsine. 
 
 As^Zng + sH'SO^ = aZnSO^ + 2H3AS. 
 Properties. Arsine is a colorless gas with a garlic-like 
 odor. It is soluble in water and combustible, forming by 
 its combustion arsenious oxide (AsgOg). 
 
 2. OF ARSENIC AND OXYGEN. 
 As arsenic has an equivalence of III or V, two oxides 
 are formed by its union with oxygen. Thus : 
 O 
 
 II 
 As 
 
 > O or AsgOg, arsenious oxide. 
 As 
 
 N 
 
 O 
 O 
 
 II 
 0=As 
 
 > O or AsgOg, arsenic oxide. 
 0=As 
 
 II 
 O 
 
 From these oxides by the addition of 3 molecules of 
 water, two acids are formed : 
 
 AsgOg -f- 3H3O = 2HgAs03, arsenious or ortho 
 arsenious acid ; and 
 
 AsgOg -f sHgO = 2HgAs04, arsenic acid. 
 
 ARSENIOUS OXIDE. 
 Formula, AsgOg. 
 Synonym, arsenious acid. 
 
 Occurrence. It occurs free in nature under the name of 
 arsenolite. 
 
Inorganic Chemistry. 201 
 
 Preparation. It is prepared by roasting arsenic ores in 
 an access of air, and condensing the vapor formed. 
 
 Properties. Arsenious oxide exists in two forms, crys- 
 talline and vitreous. The form taken by the oxide seems 
 to depend upon the amount of heat the vapor has been 
 subjected to in condensing : if less than 25o°C., the octa- 
 hedral or rhomboid crystals are formed; if more than that, 
 the vitreous variety. 
 
 The crystalline form by exposure to the air at ordinary 
 temperatures slowly changes to the vitreous variety. 
 
 Both forms are soluble in alkaline solutions, hydrochlo- 
 ric acid (HCl), and slightly in water. From its solution 
 it crystallizes in octahedral crystals. 
 
 ARSENIOUS ACID. 
 
 Formula, HgAsOj. 
 
 Preparation. It is obtainable by dissolving arsenious 
 acid in water. 
 
 Properties. Arsenious acid is a styptic liquid, with an 
 acid reaction, not very stable. 
 
 Arsenite salts are formed by substituting for the hy- 
 drogen in the acid, basic elements. These salts are not 
 easily decomposed. Among the most important of them 
 are potassium arsenite (KjAsOg), which is the principal 
 ingredient in Fowler's solution of arsenic, Scheele's green, 
 and other pigments. 
 
 Paris green is a double salt of arsenite and acetate of 
 copper. 
 
 ARSENIC OXIDE. 
 
 Formula, Ks^O^. 
 
 Preparation. This is prepared by heating arsenious ox- 
 ide (AsgOj) with nitric acid (HNO3), evaporating the 
 solution to dryness, and heating to 27o°C. 
 
202 Inorganic Chemistry. 
 
 Properties. It is an opaque, white, amorphous solid, 
 and is decomposed by heat. By the addition of water 
 arsenic acid{Vi^KsO^ is formed. 
 
 Arsenic salts are formed from the acid by substituting 
 for the hydrogen basic elements. 
 
 All forms of arsenic are poisonous, especially the ite 
 salts. 
 
 Tests for arsenic. 
 
 a. Sublimation test : 
 
 Heat arsenic in a glass tube with air. Crystals of arse- 
 nious oxide, (AsgOg) will be deposited on the glass. 
 
 b. Reduction test : 
 
 Heat arsenic in a closed tube with charcoal. A metal- 
 lic mirror of arsenic will form on sides of tube. 
 
 c. Sulphuretted hydrogen test : 
 
 Pass sulphuretted hydrogen (H^S) through a hydro- 
 chloric acid (HCl) solution of arsenic. A lemon-yellow 
 precipitate will form, which is soluble in ammonia. 
 
 d. Sulphate of copper test : 
 
 Add to an ammoniacal solution of arsenic, a solution of 
 sulphate of copper (CuSO^). A green precipitate is pro- 
 duced, which is soluble in access of ammonia. 
 
 e. Marsh's test : 
 
 Add a solution of arsenic to sulphuric acid (H3SO4), 
 and then add metallic zinc. Collect the gas given off, 
 which will contain hydrogen arsenide. This gas will have 
 the properties of hydrogen arsenide. If the gas is ignited 
 and the flame directed against a piece of cold porcelain, a 
 black stain will remain which is soluble in hyposulphite 
 of soda (NagSO^. 
 
CHAPTER XVIII. 
 
 ANTIMONY AND BISMUTH. 
 
 ANTIMONY (stfibium). 
 
 Symbol Sb. Atomic weight 122. Equivalence III and V. 
 
 History. Pure antimony was obtained by Valentine, 
 in 1492. 
 
 Occurrence. It occurs in nature, both free and com- 
 bined with oxygen, sulphur, silver, etc. 
 
 Preparation. It is prepared by melting sulphide of an- 
 timony (SbjSg) with iron. Thus : 
 
 Sulphide of antimony. Iron. Sulph, of iron. Antimony, 
 
 SbgSg + sFe = 3FeS + 2Sb. 
 Or by roasting antimony ore, thus obtaining the oxide 
 (SbgOg), which is reduced by heating with charcoal, anal- 
 ogous to the preparation of arsenic. 
 
 Properties. Antimony is a bluish-white, brittle metal 
 not easily tarnished. It fuses and burns at elevated tem- 
 peratures, producing by its combustion antimonous oxide 
 (Sb.Og). 
 
 Uses. Antimony is used largely in making type-metal. 
 
 Compounds: fi^d*^'^ 
 
 I. OF ANTIMONY AND olvaEW . 
 
 HYDROGEN ANTIMONIDE. 
 H 
 
 I 
 Formula: HoSb, Sb — H. 
 
 I 
 H 
 
 203 
 
204 Inorganic Chemistry. 
 
 Preparation znd properties. It is prepared in a manner 
 analogous to that of hydrogen arsenide (AsHg), and has 
 properties very similar to that compound. Its stain on 
 porcelain, however, is darker and not soluble in hyposul- 
 phite of soda (NagSQj). 
 
 2. OF ANTIMONY AND OXYGEN. 
 
 As antimony has an equivalence of III and V, by its 
 union with oxygen two oxides are formed. Thus : 
 
 O 
 
 II 
 Sb 
 
 >0, SbgOg, antimonous oxide. 
 Sb 
 
 II 
 O 
 
 O 
 
 II 
 0=Sb 
 
 >0, SbgOg, antimonic oxide. 
 0=Sb 
 
 II 
 O 
 
 And from these oxides, as in arsenic, ous and ic acids 
 are formed. Chemically, the oxides, acids, and salts of 
 antimony resemble those of arsenic. The principal oxide 
 of antimony is the ous oxide. 
 
 ANTIMONOUS OXIDE. 
 
 Formula, SbgOj. 
 
 Occurrence. This oxide occurs free in nature. 
 
 Preparation. It may be prepared by boiling antimo- 
 nous chloride (SbClg) with a solution of sodium carbonate 
 (Na^COs). 
 
Inorganic Chemistry. 205 
 
 Antimonous chloride. Sodium carbonate, Antimonous oxide. Sod. chloride. 
 
 2SbCl3 + sNajCOs = SbgOj + 6NaCl 
 
 Carbon dioxide, 
 
 + 3CO,. 
 
 Properties. It is a dirty-white powder, slightly soluble 
 in water, forming the ous acid. 
 
 Salts corresponding to this acid are used in medicine. 
 Tartar emetic (aKSbO, C4H4OJ) is a double salt of 
 potassium antimony tartrate. 
 
 3. ANTIMONY AND SULPHUR. 
 There are two sulphides of antimony, the ous (Sb3S3) 
 and ic (SbgSg). The former is found free in nature. 
 
 BISMUTH. 
 
 Symbol Bi. Atomic weight 210. Equivalence III and 
 
 v.- 
 
 History. It was discovered pure by Valentine in 1492, 
 
 Occurrence. Bismuth occurs free in nature, but usually 
 in combination with oxygen or sulphur. 
 
 Preparation. It is prepared by reducing 'the sulphide 
 of bismuth (BigSg) with charcoal at a high temperature. 
 
 Properties. Bismuth is a hard, brittle, reddish-white 
 metal, remaining untarnished in dry air. At high temper- 
 atures it melts and burns with a white flame, forming by 
 its combustion bismuthous oxide (BigOg). 
 
 Uses. Bismuth is used principally in forming alloys. 
 
 Compounds : 
 
 I. OF BISMUTH AND OXYGEN. 
 
 As bismuth has an equivalence of III and V, by its 
 union with oxygen two oxides are formed, the ousi^x^O^ 
 and ic (BigOg), and from them the corresponding acids 
 and salts. 
 
2o6 Inorganic Chemistry. 
 
 2. OF BISMUTH AND CHLORINE. 
 
 Chlorine being a monad, unites with bismuth to form 
 two compounds, — bismuthous chloride (Bi Clg) and bis- 
 muthic chloride (Bi Clg). In the same way are formed 
 two compounds of bismuth and sulphur, — the ous (BigSg), 
 which occurs free in nature, and the ic (BigSg). 
 
 Nitrate of bismuth, Bi(N03)3 ; the subnitrate, 0=Bi- 
 NO3 ; the carbonate, Bi3(C03)3 ; and subcarbonate, (BiO)g- 
 CO3) ; are some of the salts of bismuth used in medicine. 
 
PART IV. 
 
 ORGANIC CHEMISTRY. 
 
 207 
 
ORGANIC CHEMISTRY. 
 
 CHAPTER I. 
 
 Organic chemistry treats of the chemistr3^of the chem- 
 istry )of the carbon compounds. 
 
 The peculiarities of these compounds are, first, their ex- 
 traordinary number ; second, the few elements that enter 
 into their composition, nearly all of them being formed 
 by the union of carbon with hydrogen, nitrogen, and oxy- 
 gen ; and lastly, the large number of atoms contained in 
 each molecule. 
 
 The cause of the multiplicity of these organic com- 
 pounds is found in the peculiarity which carbon itself 
 possesses of uniting with itself and other elements, espe- 
 cially nitrogen, oxygen, and hydrogen, to form chemical 
 combinations. 
 
 Thus, for example, carbon being a tetrad, it has four 
 bonds to be satisfied by union with other bonds. If no 
 free bonds remain the compound is called saturated ; if 
 otherwise, unsaturated. Not only may these free bonds 
 become saturated by union with simple elements, but also 
 with radicals, both simple and compound, thus greatly in- 
 creasing the complexity of composition as well as the 
 number of organic compounds. 
 
 Compounds are said to be isomeric when they have the 
 same percentage composition, but differ in their physical 
 properties. 
 
 20g 
 
210 Organic Chemistry. 
 
 They are metameric when they have the same percent- 
 age composition and molecular weight, but differ in their 
 chemical properties and transformations. 
 
 They are polymeric when they have the same percent- 
 age composition, but differ in molecular weight. 
 
 Proximate analysis is the analysis of a mixture by 
 which we ascertain the definite chemical compounds which 
 exist in it. 
 
 Ultimate analysis is that determining the percentage of 
 the elements in any chemical compound. 
 
 Organic compounds form an homologous series when 
 their general formulae differ from one another by CHg, 
 viz., by the replacement of a hydrogen by CHg. Thus 
 the hydrocarbon series (CH^) are homologous, as each 
 formula differs from the preceding one by CHg, and this 
 series can therefore be expressed by the general formula, 
 C„Hgn+8 (« representing the number of atoms taken of 
 each element to form the molecule). 
 
 Organic chemistry may be divided into two great divi- 
 sions, called the fatty and aromatic groups, the fatty 
 group being derived from methane (CH4) and the aro- 
 matic group from benzine (CgHg). 
 
 For formation of acids, alcohols, aldehides, ethers, and 
 compound ethers, see ^a^ge 216. 
 
CHAPTER II. 
 
 FATTY GROUP. 
 
 HYDROCARBONS. 
 
 Compounds consisting of only carbon and hydrogen 
 are called hydrocarbons. They form a number of interest- 
 ing series, the compounds of each series differing from 
 one another by CHg. These series start from the 
 saturated compound methane (CH^), and from which is 
 derived the following homologous series, viz. : By the 
 addition of CHg, CH4, CgHg, CgHg, C4H10, CgH^g, 
 etc., and can be represented by the general formula 
 (5 ^4^H,„ + =, called the paraffin series. 
 
 All of these homologous series represent saturated 
 compounds, but by taking away from each formula one 
 molecule or two atoms of hydrogen we have formed a 
 number of homologous series, whose general terms are 
 expressed thus: QH^, CnH^_„ QH^_^, C„H^_fi, etc., 
 and whose compounds are unsaturated. These series are 
 represented in the following table : 
 
 C„H 
 
 Paraffin series. 
 
 Olefine series. 
 
 Acetyline series, 
 
 etc. 
 
 V^nflan -|- aj 
 
 CnH^u, 
 
 CuH,„_„ 
 
 CnHai- 
 
 Methane. 
 
 Methene. 
 
 
 
 CH4, 
 
 CH„ 
 
 
 
 Ethane. 
 
 Ethene. 
 
 Ethine. 
 
 
 CgHg, 
 
 CgH^, 
 
 CgHg, 
 
 
 Propane. 
 
 Propene, 
 
 Propine. 
 
 Propone. 
 
 CgHg, 
 
 CsHe, 
 
 C3H4, 
 
 CsHa 
 
 211 
 
212 Organic Chemistry. 
 
 Butane. Butene. Butine. Butone. Butune. 
 
 ^4^101 C4H8, C4HJ, C4H4, C4H2, etc. 
 
 The name of each compound ends in ne with the prefix 
 a, e, i, o, or u, in order in each series, starting with a for 
 the highest series (C„H,„ + ,). 
 
CHAPTER III. 
 METHANE COMPOUNDS AND DERIVATIVES. 
 
 METHANE. 
 
 Synonyms : Marsh gas ; fire damp. 
 
 H 
 
 1 
 Formula: CH4, H — C — H. 
 
 H 
 
 Occurrence. Methane occurs free in marshes and coal 
 mines, and is the product of the slow decomposition of 
 organic substances in the absence of oxygen. 
 
 Preparation. It is best prepared chemically by heating 
 sodium acetate (CgHgNaOg) with sodium hydrate 
 (NaOH). Thus: 
 
 Sod. acetate. Sod. hydrate. Sod. carb. Methane. 
 
 CgHgNaOg + NaOH = NagCOg + CH4. 
 
 Properties. Methane is a colorless, odorless gas, easily 
 combustible, and burning with a blue flame. It forms an 
 explosive compound when mixed with air or oxygen. 
 
 Use. It forms an important constituent of illuminating 
 gas. 
 
 Compounds of Methane : 
 
 HALOGEN SUBSTITUTIONS. 
 
 By substituting halogen elements for one or more 
 hydrogen atoms in methane we obtain a series of com- 
 
 813 
 
214 Organic Chemistry. 
 
 pounds called Haloid ethers, among the most important 
 of which are : 
 
 Methyl chloride : CH.Cl., H — C — H 
 
 I 
 CI 
 
 This compound does not occur free in nature, but is 
 produced by the action of hydrochloric acid (HCI) upon 
 methyl alcohol (CH^O). It is a colorless gas with a 
 sweetish taste. 
 
 Methyl bromide, CHgBr. This compound is pre- 
 pared by the action of hydrobromic acid (HBr) on 
 methyl alcohol (CH4O). It is a colorless liquid with an 
 ether-like odor. 
 
 Methyl iodide, CH3I. This is prepared like the 
 above by the action of hydroiodic acid (HI), upon methyl 
 alcohol (CH4O). It forms a colorless liquid, which is 
 easily decomposed on exposure to the light. 
 
 H 
 
 I 
 Chloroform: CHCI3, CI— C— CI 
 
 I 
 
 CI. 
 Chloroform is best prepared by the action of calcium 
 hypochlorite Ca(C10)3 on common alcohol (CgHgO). The 
 process is a complicated one, but can be expressed in a 
 general way by the following formula : 
 
 Alcohol. Cal. hypochlor. Chloroform. Cal. carb. 
 
 2C2HeO + 5Ca(C10)2 = aCHClj + 2CaCOs 
 
 Cal. chlor. Cal. hydrate. Water. 
 
 + 2CaClg + Ca(0H)2 + 4H2O. 
 It is a colorless liquid with a pleasant odor, but slightly 
 combustible, burning with a green flame. 
 
Organic Chemistry. 215 
 
 It is soluble in alcohol and ether, but slightly soluble in 
 water. When perfectly pure it sinks readily in water 
 without causing a troubling, and will not redden Htmus 
 paper. 
 
 It is used principally as a solvent and an anaesthetic. 
 
 Bromoform, CHBrg. This is a colorless liquid with 
 an odor like chloroform. 
 
 lODlFORM, CHI3. lodiform is best prepared by the 
 action of iodine on a solution of sodium carbonate 
 (NagCOs) in alcohol (CgHeO). 
 
 Thus prepared it is a yellowish crystalline flaky solid 
 with saffron-like odor. It is insoluble in water, but soluble 
 in alcohol and ether. It is used principally in medicine. ' 
 
 CI 
 
 I 
 Carbon tetrachloride : CCI4, CI — C — CI 
 
 i 
 
 CI. 
 This compound is usually prepared from chloroform, 
 and is a colorless liquid with a pleasant odor. 
 
CHAPTER IV. 
 HYDROXYL SUBSTITUTION. 
 
 By substituting hydroxyl (OH) for one hydrogen in a 
 hydrocarbon, an alcohol is produced, for two hydrogens an 
 aide/tide, and for three hydrogens an organic acid. 
 
 These substitutions can be represented as follows, 
 taking methane (CH^) as the hydrocarbon : 
 (OH) 
 
 I 
 1st. An alcohol, H—C—H,CHg(OH), methyl ALCOHOL. 
 
 I 
 H 
 
 (OH) O 
 
 i II 
 
 2. An aldehide, H— C— (OH), or H— C + HgO.CHgO 
 
 I I 
 
 H H 
 
 methyl aldehide. 
 
 (OH) O 
 
 I II 
 
 3d. An acid, H— C— (OH), or H— C + H3O, CHO, 
 
 I I 
 
 (OH) OH 
 
 (OH), formic ACID. 
 
 Compound ethers or esters are formed from acids 
 
 by substituting for the hydroxyl hydrogen of the acid, 
 
 hydrocarbon radicals or alcohol rests (alcohol minus hy- 
 
 216 
 
Organic Chemistry. 217 
 
 droxyl). Thus by substituting for the hydroxyl hydro- 
 gen of formic acid CHO(OH), methyl (CHg), there is 
 formed methyl formic ether, CHj, CHOg- 
 
 Compound ethers are formed from alcohol by replacing 
 the hydroxyl hydrogen of the alcohol by acid rests (acid 
 minus hydroxyl). 
 
 Ethers are formed from alcohols by heating them with 
 sulphuric acid (H3SO4), and consist simply of two hydro- 
 carbon radicals, as methyl (CHj) united by oxygen. Thus : 
 CH3 — O — CHj is methyl ether. 
 
 Having now considered the formation of alcohols, acids, 
 etc., we come to the study of those connected with the 
 methane compounds. 
 
 Methyl alcohol, CH3OH. 
 
 Synonyms. Carbonal, wood spirits. 
 
 Preparation. It is obtained with crude acetic acid in 
 the distillation of wood. 
 
 Properties. Methyl alcohol is a colorless mobile liquid 
 with the odor and taste of common alcohol. It is com- 
 bustible and has remarkable dissolving properties, readily 
 dissolving essential oils, varnishes, etc. 
 
 Uses. It is used principally in the manufacture of an- 
 iline dyes and as a solvent. Alcohols unite with acids to 
 form compound ethers or esters, a molecule of water being 
 given off. 
 
 Thus methylalcohol(CHjOH)with nitric acid (HNO3) 
 forms methyl nitric acid or ether (CH3NO3) and water. 
 
 Methyl alcohol. Nit. acid. Methyl Nit. acid. Water. 
 
 CH3OH -f- HNO3 = CH3NO3 -f HgO. 
 These esters are formed by simply replacing the hy- 
 droxyl hydrogen of alcohol with an acid rest (acid minus 
 hydroxyl). Thus mythyl alcohol with sulphuric acid 
 (H3SO4) forms methyl sulphuric acid{CH^O, HSO3) or 
 
2i8 Organic Chemistry. 
 
 (CHg, HSO4), with phosphoric acidCHgPOi) methyl phos- 
 phoric acid (CYl^, H3PO4). If there remains a replaceable 
 hydrogen in any of these esters, viz., a hydrogen in the 
 acid rest as in the methyl sulphuric and phosphoric esters, 
 — the compounds are called acids . or ester acids, and 
 the hydrogens are replaceable with metallic elements as 
 sodium and potassium, forming organic salts. Thus 
 methyl sodium sulphate has the formula CH3, NaS04. 
 
 Methyl ether: (CH3)aO, or CHg — O — CHj is 
 obtained by heating methyl alcohol (CHjOH) with 
 sulphuric acid, the alcohol being split up into ether and 
 water thus : 
 
 Methyl alcohol. Methyl ether. Water. 
 
 2CH3OH = (CH3),0, + H,0 
 
 H OH 
 
 I I 
 
 Methyl aldehide : CHgO.H— C =: O or H— C— OH. 
 
 A 
 
 Preparation. Methyl aldehide is prepared by passing 
 the vapor of methyl alcohol (CH3OH), mixed with air, 
 over a heated platinum spiral. If the oxidation is effected 
 with stronger agents, as sulphuric acid (H2SO4) and man- 
 ganese dioxide (MnOg), three hydrogens are replaced by 
 OH, and formic acid, CHO(OH), and water are produced: 
 
 Formic acid. Water. 
 
 CH(0H)3=CH0(0H) + H3O 
 
 OH O 
 
 I II 
 
 Formic Acid : CHO(OH), H— C— OH or H— C + H^O. 
 
 I I 
 
 OH H 
 
 Occurrence. It exists in nature in ants, pine needles, 
 urine, and blood. It also is a product of the decomposi- 
 tion of sugar, starch, gums, etc. 
 
Organic Chemistry. 219 
 
 Preparation. Formic acid is best prepared by the de- 
 composition of oxalic acid (C2H2O4) in glycerine, as thus 
 presented : 
 
 Oxalic acid. Carbon dioxide. Formic acid. 
 
 CgHgOi = CO2 + CHO(OH) 
 Properties. It is a colorless acid liquid soluble in water 
 and alcohol. Its vapor is combustible. It is a good re- 
 ducing agent, uniting with oxygen to form carbonic diox- 
 ide (CO3) and water. Thus : 
 
 Formic acid. Oxygen. Carbon. Water. 
 
 CH^Og +0 = CO3 -f HgO 
 Salts of this acid can be formed by replacing one hy- 
 drogen (the hydrogen of the hydroxyl OH) by a metallic 
 element, as sodium, etc. Thus : sodium formate has the 
 formula CHO, NaO or CHOg, Na; lead formate, 
 (CH02)2Pb, etc. 
 
CHAPTER V. 
 
 OXYGEN SUBSTITUTIONS. 
 
 Oxygen may be substituted for the hydrogen in me- 
 thane, but as oxygen is a diad it will take two hydrogens 
 to satisfy one oxygen. 
 
 Carbonyl: CO, >C = O. 
 
 Synonym: Carbon monoxidS. 
 
 Carbonyl is a compound radical with an equivalence of 
 two, and has been already treated of under inorganic 
 chemistry. From it organic compounds are formed by 
 saturating its free bonds with other elements or com- 
 pound radicals. Thus with sulphur it forms carbonyl 
 sulphide (S = C = O) ; with chlorine, carbonyl chloride, 
 CI — C=0, (COClg) ; with amodogen (NHg), urea, 
 
 CI 
 
 NHg— C=0, CH4NgO, etc. 
 
 •I 
 NHg 
 
 Urea, CH^NgO. 
 
 Synonym, Carbamide. 
 
 Occurrence. Urea is found in the urine of all mam- 
 malia and in small amount in many animal juices. It is 
 the product of the oxidation of the nitrogenous elements 
 of the body. 
 
 Preparation. It is best prepared by the decomposition 
 of ammonium cyanide (NH4, CNO) by heat, as repre- 
 sented in the following equation : 
 
 220 
 
Organic Chemistry, 221 
 
 Ammonium cyanide. Urea. 
 
 NH^, CNO = CH^NgO 
 
 Properties. Urea crystallizes in four-sided prisms and 
 is soluble in water and alcohol. It has a bitter, cooling 
 taste like saltpetre, and is readily decomposed by heat, 
 setting free ammonia. Boiling with water, alkalies, or 
 acids the following decomposition takes place : 
 
 Urea. Water. Ammon. carb. 
 
 CH^N.O + 2H3O = (NHJgCOg 
 
 This decomposition also takes place spontaneously in 
 urine, causing its alkaline fermentation. 
 
 Compounds. Urea combines with acids to form salts. 
 Thus with nitric acid (HNO3) it forms nitrate of urea 
 (CH4NgO, HNO3), which is but slightly soluble in 
 water ; hence urea can be readily separated from its solu- 
 tion by first converting it into the nitrate by the addition 
 of nitric acid. 
 
 Compound ureas are formed by replacing one or more 
 of the hydrogens in urea with hydrocarbon radicals, as 
 methyl (CH3), ethyl (CgHj), etc., thus forming methyl 
 urea (CHjNgO, CHj), ethyl urea (CHgNgO, CgHg), etc. 
 
 Carbon dioxide : COg, O = C = O. 
 
 This compound has been already studied in inorganic 
 chemistry. 
 
CHAPTER VI. 
 SULPHUR SUBSTITUTIONS. 
 
 As oxygen may take the place of hydrogens in methane, 
 in like manner sulphur may be substituted. If sulphur be 
 substituted for one hydrogen, sulphur being a diad, methyl 
 sulphide, (CHg)3S, is produced ; for two hydrogens, methyl 
 siilphal-dehide (CHgS), etc. 
 
 The most important compound of this group thus pro- 
 duced is carbon bi-sulphide, CSg, all the hydrogens being 
 replaced. 
 
 Carbon bi-sulphide : CSg, S = C = S. 
 
 Preparation. Carbon bi-sulphide is best prepared by 
 passing sulphur vapor over glowing coals, the following 
 reaction taking place : C -|- Sg = CSg. 
 
 Properties. It is a colorless liquid with a disagreeable 
 odor and high refractive power ; insoluble in water. It 
 has marked solvent properties, dissolving iodine, bromine, 
 phosphorus, oils, fats, etc. 
 
 Uses. It is used principally as a solvent, and in optics 
 for its high refractive properties. 
 
 Carbon oxy-sulphide : COS, O = C :i= S. 
 
 This compound stands in composition midway between 
 carbon bi-sulphide (CSg) and carbonic dioxide (COg). 
 
 Properties. It is an an inflammable gas and easily de- 
 composed by water into carbon dioxide and sulphuretted 
 hydrogen. Thus : 
 
 Garb. oxy. sulph. Water. Garb. diox. Sulph. hydrog, 
 
 COS + HgO = COg -f HgS. 
 
Organic Chemistry. 223 
 
 SULPHONIC ACIDS. These acids are produced by re- 
 placing the hydroxyl of sulphuric acid (H3SO4) with a 
 hydrocarbon radical. Thus, methyl sulphonic acid has the 
 formula CHgHSOg ; ethyl sulphonic acid, CgHg, HSOg, 
 etc. 
 
 A mercaptan is an alcohol with oxygen replaced with 
 sulphur. 
 
CHAPTER VII. 
 
 NITROGEN SUBSTITUTIONS. 
 
 The nitrogen derivatives of the hydrocarbons are 
 numerous and important. From them are formed the 
 amines, the amides, and the nitrils. 
 
 The hydrogens in methane may be replaced by the 
 simple element nitrogen, which has an equivalence of 
 
 H 
 three, forming hydrocyanic acid, HCN, or | ; by the 
 
 C=N 
 compound radical NHg, called amodogen, which has an 
 equivalence of one, forming methylamine, CHgNH^, or 
 H 
 
 I 
 H — C — NHj ; or by NH called imodogen, which has an 
 
 H H 
 
 equivalence of two, thus forming CHgNH, or | 
 
 NH=C— H. 
 
 These compounds are much better understood by con- 
 sidering them as derived from ammonia (NHg). 
 
 Amines. An amine is a substituted ammonia with the 
 hydrogens replaced by hydrocarbon radicals. 
 
 The amines may be primary, secondary, or tertiary, de- 
 pending upon the number of hydrogens replaced by the 
 hydrocarbons. They resemble ammonia more or less, 
 and unite directly with acids to form salts. Among the 
 most important amines are: 
 
 224 
 
Organic Chemistry. 225 
 
 CHs 
 / 
 
 MethYLAMINE: CH3NH3, or N — H 
 
 \ 
 H. 
 
 CH3 
 / 
 
 DiMETHYLAMINE : (CH3)2NH, or N — CH3 
 
 H. 
 CH3 
 / 
 
 Tri-methylamine. (CHg)3N, or N — CH3 
 
 \ 
 CH3. 
 
 Amides are substituted ammonias in which the hydro- 
 gens are replaced by acid radicals — the acid minus the 
 hydroxy! (OH). T\\.m^ formamide (^W.^, CHO)is derived 
 from formic acid, CHO(OH), the acid radical CHO re- 
 placing one of the hydrogens in ammonia (NH3) — 
 CHO 
 
 / 
 N — H ; acetamide (NHg, C3H3O) is derived in the same 
 
 H. 
 
 C2H3O 
 
 / 
 way from acetic acid, Cg H 3 0(0 H) — thus : N — H ; as is also 
 
 V 
 
 H 
 cyanamide (CN, NHg) derived from cyanic acid — CN(OH), 
 CN 
 
 / 
 N— H, etc. 
 \ 
 H. 
 
 As the amines may be primary, secondary, or tertiary, 
 
226 Organic Chemistry. 
 
 taking the prefixes mono, di, or tri, so may the amides 
 take like prefixes as one, two, or three of the hydrogens 
 in ammonia are replaced by acid radicals. 
 
 Imides. We have, so far, only considered those substi- 
 tutions for the hydrogens that have an equivalence of 
 one, but two hydrogens in ammonia may be replaced by 
 diad radicals ; such compounds are called imides. Thus 
 carbimide (NHCO) is such a compound, and may be rep- 
 CO 
 
 resented thus: N — H, one hydrogen of the ammonia 
 being replaced by the diad radical carbonyle (CO). 
 
 NiTRlLS. If all the hydrogens of ammonia are replaced 
 by a triad radical we have a class of compounds called 
 nitrils. Among the most important nitrils derived from 
 methane is — 
 
 Hydrocyanic acid : HCN, N^CH. 
 
 Synonym. Prussic acid. 
 
 Occurrence. It does not occur free in nature, but is the 
 decomposition product of compounds found in the peach 
 and cherry pits, flowers of the bitter almond, etc. 
 
 Preparation. It is best prepared by passing sulphuret- 
 ted hydrogen (HgS) over mercuric cyanide Hg (CN)^. 
 Thus: 
 
 Merc, cyanide. Sulph. hydrogen. Prussic acid. Merc, sulphide. 
 
 Hg(CN)2 + H^S = 2HCN + HgS. 
 
 Properties. Prussic acid is a colorless liquid, and the 
 most active poison known. 
 
 It is soluble in water, alcohol, and ether, and has an 
 odor like peach blossoms. It unites with acids to form 
 salts by the replacement of its hydrogen. 
 
 Compounds. Among the most important cyanides are 
 potassium cyanide (KCN), sodium cyanide (NaCN), am^ 
 
Organic Chemistry. 227 
 
 monium cyanide (NH4CN), mercuric cyanide, Hg(CN)g, 
 and the iron cyanides. 
 
 Potassium cyanide, KCN. 
 
 Preparation. It is best prepared by adding hydrocyanic 
 acid (HCN), to an alcoholic solution of potassium hydrate 
 (KOH). Thus : 
 
 Prussia acid. Pot. hydrate. Pot. cyanide. Water. 
 
 HCN + KOH = KCN -j; H^O. 
 
 The potassium cyanide thus formed being insoluble in 
 alcohol is precipitated. 
 
 Properties. Potassium cyanide crystallizes in cubes, but 
 deliquesces on exposure to the air. In solution it decom- 
 poses rapidly into an amorphous mass called potassium, 
 formate (CHKO3), and ammonia NHg. Thus: 
 
 Pot. cyanide. Water. Fot. formlde. Ammonia. 
 
 KCN + 2H2O = CHKO2 + NH3. 
 
 It has the odor and poisonous properties of hydrocyanic 
 acid. It is also a powerful reducing agent, taking up 
 oxygen readily, thus forming potassium, cyanate (KCNO). 
 
 Iron cyanides. These cyanides are seldom found in 
 the separate state on account of their tendency to form 
 double salts. The two principal cyanides of iron are the 
 
 CN 
 
 / 
 ferrous cyanide, Fe(CN)g, Fe , and ferric cyanide, 
 
 CN 
 
 CN 
 CN CN I 
 
 I / CN— Fe— CN 
 
 Fe3(CN)e, CN-Fe^ , I , or 
 
 / I \ CN— Fe— CN 
 
 CN CN, CN I 
 
 CN 
 
228 Organic Chemistry. 
 
 iron thus taking the equivalence of two or four, or six with 
 use of two atoms to the molecule. 
 
 Among the most important double salts a.re potassium 
 ferrocyanide or yellow prussiate of potash, K4Fe(CN)j ; 
 potassium ferricyanide, KgFe3(CN)i3, called red prussiate 
 of potash; and ferri-ferrocyanide, (Feg)^, [Fe(CN)jJg, or 
 Prussian blue. 
 
 Cyanic acib. Beside the hydrocyanic acid (HCN), in 
 which the hydrogen is united directly with cyanogen 
 (CN), we have cyanic acid (HCNO), in which the hydrogen 
 and cyanogen are united by means of oxygen. Thus: 
 CN— O— H. 
 
 The hydrogen in this acid can be replaced by basic ele- 
 ments or radicals forming salts called cyanates, as, for 
 example, potassium cyanate (KCNO), ammonium cyanate 
 (NH4, CNO), methyl cyanate {CH^, CNO), etc. 
 
 SULPHO-CYANIC ACID. If the oxygen in cyanic acid 
 be replaced by sulphur, sulpho-cyanic acid (CNHS) is pro- 
 duced, and from this acid the sulpho-cyanates are formed 
 by replacing the hydrogen with basic elements or radicals. 
 Thus, for example, we have potassium sulphocyanate 
 (CNKS), ammonium sulphocyanate (CNS, NH^), etc. 
 
CHAPTER VIII. 
 PHOSPHORUS AND METALLIC SUBSTITUTIONS. 
 
 Phosphines. If phosphorus is substituted for the 
 nitrogen in the amine compounds a new group of com- 
 pounds is obtained, called phosphines. 
 
 In the same way as was formed mono, di, and tri- 
 ■methylamine, we now have by the substitution of phos- 
 phorus for the nitrogen, mono, di, and tri methyl-phos- 
 phine as thus represented : 
 
 CH3 
 / 
 
 MethyUphosphine, PHgCHg, or P— H. 
 
 H 
 
 CH3 
 / 
 
 Di-methyl-phosphine, PH, (CHg)^, or P — CHg. 
 
 \ 
 H 
 
 CH3 
 
 / 
 Tri-methyl-phosphine, P(CH3)3, or P — CHg. 
 
 ^CH3 
 
 PHOSPHINIC ACIDS AND ETHERS. 
 Phosphinic ACID and ETHERS are obtained from 
 phosphoric acid (H3PO4) the same way that nitro com- 
 pounds are obtained from nitric acid (HNO3), and sulphuric 
 
 229 
 
230 Organic Chemistry. 
 
 acids and ethers are obtained from sulphuric acid (HgSO^), 
 viz. : in the acid compounds by replacing the hydroxyl 
 (OH) of the acid by a hydrocarbon radical, as methyl 
 (CHg), and in the ether compounds by thus replacing 
 the hydrogen only. For example : The hydroxyls of phos- 
 
 OH 
 / 
 phoric acid (H3PO4) maybe represented thus: PO — OH. 
 
 OH 
 Now if one or more of these hydroxyls are replaced by a 
 hydrocarbon radical as methyl (CH3), a methyl phosphi- 
 
 CH3 
 / 
 nic acid is formed, a.s di-methyl phosphinic acid, PO — CHj, 
 
 OH 
 but if the hydrogens alone are thus replaced a compound 
 ether or ester is obtained, as di-methyl phosphonic ether, 
 OCH3 
 / 
 PO — OCH3. Such esters are sometimes called ester 
 
 OH 
 
 acids, as one or more hydrogens still remain replaceable. 
 
 METALLIC DERIVATIVES. 
 
 One or more of the hydrogens in methane may be re- 
 placed by a metallic element, thus forming a new set of 
 compounds. For example, zinc methyl has the formula 
 Zn(CH3)2 — zinc being a diad, it will take two methyl 
 radicals to satisfy it. Arsenic being a triad, methyl arsenic 
 would have the formula As(CH3)3, etc. But beside these 
 single salts, double salts are formed by one or more of the 
 bonds of the metallic element being saturated with other 
 
Organic Chemistry. 231 
 
 elements, as chlorine. Thus, for example, di^methyl ar- 
 senic chloride would have the formula As(CH3)3Cl, or 
 CH3 
 / 
 As— CHj. 
 \ 
 CI 
 
CHAPTER IX. 
 
 ETHANE COMPOUNDS. 
 
 Having considered the methane compounds, we come 
 
 to the next of the QH^„+2 series, called ethane; and 
 
 from it, by taking away two hydrogens, the unsaturated 
 
 compound ethene or ethylene belonging to the C„Hj„ 
 
 series, and ethine or acetylene (CgHj) of the C„Hj„_ 
 
 series. 
 
 H H 
 
 I I 
 Ethane : CgHg, or H— C— C— H. 
 
 H H 
 
 Preparation. It is best prepared by the action of water 
 on zinc ethyl, Zn (CgHg)^. Thus : 
 
 Zinc ethyl. Water. Ethane. Zinc hydrate. 
 
 (C3Hg)3Zn + 2H3O = 2C3H6 + Zn(OHg) 
 
 Properties. Ethane is a colorless gas, combustible and 
 
 burning with a blue flame. 
 
 H H 
 
 I I 
 
 Ethylene : C2H4, or C = C. 
 
 H H 
 Synonyms, Ethine or olefiant gas. 
 
 H H 
 Acetylene : CgHg, or | | . 
 
 C=C 
 232 
 
Organic Chemistry. 233 
 
 Synonym. Ethine. Both of these compounds have al- 
 ready been considered in inorganic chemistry. 
 
 As ethane is formed by the union of two carbon radi- 
 cals, and as the hydrogens of either one or both may be 
 replaced by such elements as chlorine, it follows that there 
 may be two isomeric series of compounds formed, having 
 the same formula yet differing in construction. If only 
 one hydrogen be replaced, isomerism is not possible, for 
 the element occupies the same relative position in refer- 
 ence to C and H wherever it is placed ; but if two hydro- 
 gens be thus replaced, the compounds resulting may be 
 constructed differently, as is the case with ethylene chlor- 
 
 H H H H 
 
 II II 
 
 ide(CoHXL). Thus: CI— C— C— CI and H— C— C— CI 
 
 II .11 
 
 H H H CI 
 
 are isomeric compounds, each having the same formula 
 
 (C2H4CI3), but entirely different substances. 
 
 HALOGEN SUBSTITUTIONS. 
 
 One or more of the hydrogens in ethane may be re- 
 placed by the halogen elements, iodine, bromine, or 
 chlorine, thus forming ethyl iodide, bromide, or chloride, 
 which may be either mono, di, or tri. 
 
 Among the most important of these compounds are 
 ethyl mono-chloride (CgHjCl), ethyl di-chloride, more com- 
 monly called ethyline chloride (CgH^Cl^), ethyl bromide 
 (CgHgBr), and ethyl di-bromide, commonly called ethylene 
 bromide (C2H4Br2). The ethyl chlorides are liqirids hav- 
 ing a pleasant odor, while the bromides are crystalline 
 solids. 
 
CHAPTER X. 
 
 HYDROXYL SUBSTITUTIONS. 
 
 The formation of alcohols, aldehides, and acids have 
 already been explained (page 2i6) in considering the me- 
 thane compounds, and as their formation is the same in 
 all the hydrocarbon series, we now go on to examine them 
 as applied to ethane compounds. 
 
 H H 
 
 I I 
 Ethyl Alcohol: CgHgCOH), H— C— C— OH. 
 
 H H 
 
 Synonym. Alcohol. 
 
 Preparation. Alcohol can be prepared chemically by 
 the action of potassium hydrate (KOH) upon ethyl sul- 
 phuric acid CgHgjHSO^. Thus: 
 
 Pot. hydrate. Ethyl sulph. acid. Alcohol. Pot. sulphate. Water, 
 
 2KOH + C2H5, HSO4 = CgHgCOH) + K3SO4 + H3O. 
 
 Alcohol is made commercially by fermenting grape 
 sugar (glucose) with yeast, the grape sugar breaking up 
 into alcohol and carbon di-oxide. Thus : 
 
 Glucose. Alcohol. Carb. dioxide. 
 
 CeHi.Oe = 2Z^Yi^{0Yi) + aCO^. 
 
 Alcohol can be made from any material containing 
 either starch or sugar, as rice, rye, corn, beets, grapes, etc. 
 By the addition of water, cane sugar (CigHggOji) and 
 starch (CgH^jOg) are both converted into glucose 
 
 234 
 
Organic Chemistry. 235 
 
 (CgHijOg). The alcohol thus obtained by fermentation 
 is not pure, but contains other alcohols, especially amyl 
 alcohol and water. 
 
 The water may be gotten rid of by distillation, the 
 boihng point of alcohol being much below that of water. 
 
 Prjoperties. Alcohol is a colorless mobile fluid with an 
 ether-like odor. It boil-s at 85°C., but does not frepze. 
 
 It is combustible, burning with a very hot but slightly 
 luminous flame. 
 
 It absorbs moisture readily, and extracts the water of 
 crystallization from many salts. It has marked solvent 
 properties readily dissolving iodine, bromine, fats, oil, 
 resins, etc. By uniting with acids alcohol forms com- 
 pound ethers. With sulphuric acid (HgSO^), it forms 
 ethyl sulphuric acid or ester (CgHg, HSO4); with nitric 
 acid (HNO3), ethyl nitric ether (CgHg.NOg), etc. Salts 
 are formed from these acids by replacing the hydrogen of 
 the acid with basic elements, as potassium, thus forming 
 with ethyl sulphuric acid, ethyl potassium sulphate {C^^i 
 KSO4). If alcohol is heated with sulphuric acid it forms 
 (see methyl ether), SULPHURIC ETHER, C4H10O, 
 
 CgHg 
 
 >0. 
 or C2H5 
 
 Synonym. Ether. 
 
 Preparation. Ether is made by heating nine parts of 
 sulphuric acid (HjSOj) with five parts of alcohol. 
 
 Ethyl sulphuric acid (CjHg, HSOj) is first produced 
 but is afterwards decomposed, splitting up into ether and 
 sulphuric acid. The either is distilled off with some of 
 the alcohol, and is freed from the latter with caustic lime 
 Ca(0H)3. 
 
 Properties. Ether is a colorless mobile liquid with a 
 
236 Organic Chemistry. 
 
 pleasant odor, producing insensibility when inhaled. It is 
 
 combustible, burning with a luminous flame. 
 
 Uses. It is used as a solvent and as an anaesthetic. 
 
 H OH HO 
 
 II I II 
 
 Aldehide: C.H.O, H— C— C— OH.orH— C— C+HoO. 
 
 II II 
 
 H H. H H. 
 
 Synonym. Ethyl aldehide. 
 
 Preparation. It is best prepared by the action of 
 chromic acid (H2Cr04), on alcohol. 
 
 Properties. Aldehide is a colorless, mobile liquid with 
 a suffocating odor. It is soluble in ether and com- 
 bustible. 
 
 Compounds. Chlorine can be substituted for one or 
 more of the hydrogens in aldehide, forming compounds, 
 the most important of which is : 
 
 Chloral, CgHClgO. 
 
 Preparation. Chloral is best prepared by the action of 
 chloroform upon alcohol, the alcohol first being converted 
 into aldehide and afterward into chloral. 
 
 Properties. It exists as a colorless liquid, which added 
 to water forms chloral hydrate, (C2HCl30)H20, a tran- 
 sparent crystalline substance, having a peculiar odor and 
 biting taste. It is used extensively in medicine. 
 
 H OH 
 
 I I 
 Acetic acid: CaH30(0H), H— C— C— OH, or 
 
 H O 
 
 I II 
 H— C— C + H3O. 
 
 H OH 
 
 H OH 
 
Organic Chemistry. 237 
 
 Synonym. Vinegar. 
 
 Occurrence. It is found in many plants and fruits; 
 also in some of the secretions of animals. 
 
 Preparation. Acetic acid is prepared by the oxidation 
 of alcohols (acetic fermentation), by the distillation of 
 wood, and chemically by the action of potassium hydrate 
 (KOH) upon methyl cyanide (CH3, CN). Thus : 
 
 Methyl cyanide. Pot. hydrate. Water. Acetic acid. Ammonia. 
 
 CHg, CN + KOH + HgO = C2H4O2 + NH3. 
 
 Properties. At ordinary temperatures acetic acid is a 
 cdlorless liquid having a sharp odor and caustic properties. 
 As it has one replaceable hydrogen (that of the hydroxyl 
 OH), it is mono-basic, and unites readily with bases to 
 form salts, among the most important of which are 
 potassium acetate (KCgHjOg), plumbic acetate, so-called 
 "sugar of lead," P^CgH 303)2, and cupric acetate, or 
 " verdigris," Cu(C2HgOg)g. 
 
 GLYCOLS, ETC. 
 
 We have so far only considered those alcohols, aide- 
 hides, and acids in which the hydrogens of one hydro- 
 carbon radical forming ethane have been replaced by 
 hydroxyl. 
 
 If, however, the hydrogens of both radicals be replaced 
 by hydroxyl, we have formed a new set of alcohols, aide- 
 hides, and acids. Alcohols thus formed are called glycols, 
 and the one formed from ethane is ethylene GLYCOL, 
 OH OH 
 
 C2H4(OH)2, H— C— C— H 
 
 H H 
 Properties. It is a colorless liquid, quite easily decom- 
 
238 Organic Chemistry. 
 
 posed by oxidation into glycollic acid CgH40g, which 
 
 exists in the form of a white deliquescent mass. This 
 
 acid has one replaceable hydrogen, and forms salts by its 
 
 union with the basic elements, such as calcium, forming 
 
 calcium glycollate, Ca(C2H30g)g. 
 
 OH OH 
 
 II II II 
 
 Glycollide, CoHoO,, OH— C— C— oh, or C— C + 
 
 II II 
 
 H H H H 
 
 2H3O, is the aldehide of this order, and oxalic acid the 
 
 corresponding acid. 
 
 OH OH 
 
 Oxalic acid: C203(0H)3, OH— C— C— OH, or 
 
 OH OH 
 O O 
 
 II II 
 
 C— C + 2H2O 
 
 OH OH 
 
 Occurrence. It occurs in many vegetables and fruits in 
 the form of oxalates. 
 
 Preparation. It is best prepared by melting sawdust 
 with potassium hydrate (KOH.) 
 
 Properties. Oxalic acid as thus prepared crystallizes in 
 transparent prisms. 
 
 It is soluble in water and alcohol and is very poisonous. 
 
 It readily decomposes by heat into water, carbon dix- 
 oxide (COj) and monoxide (CO). Thus : 
 
 Oxalic acid. Carb. diox. Carb. mcnox. Water. 
 
 C2H2O4 = COg + CO + HgO. 
 
 Compounds. Oxalic acid is di-basic, having two replacea- 
 ble hydrogens, CjOg(OH)g, and therefore unites with 
 
Organic Chemistry. 239 
 
 basic elements to form either acid or neutral salts. Among 
 the most important of these salts are potassium oxalate 
 (KgCgO^), acid potassium oxalate o'c potassium hydro-oxa- 
 late (KHC3O4), calcium oxalate (CaC3 04), etc. 
 
 By replacing one or both of the hydrogens with hy- 
 drocarbon radicals, as ethyl (C3H5) or methyl (CH3) oxalic, 
 acids or esters are formed. Thus we have by the replace- 
 ment of one hydrogen with ethyl, ethyl oxalic acid 
 CgHgC2H04) of both hydrogens, ethyl oxalic ester or 
 ether [(C,Hb)„C20J. 
 
CHAPTER XI. 
 
 SULPHUR AND OTHER SUBSTITUTIONS OF ETHANE. 
 
 SULPHUR SUBSTITUTIONS. 
 
 The sulphur substitutions of ethane are not very impor- 
 tant but among them are etkyl sulphide {C^}r{^)^S, a color- 
 less liquid having a garlic-like odor ; and ethyl sulphaldehyde 
 (CjH^S), a substance corresponding in composition to 
 ethyl aldehyde, viz. : two of the hydrogens in ethane 
 being replaced by sulphur instead of the hydroxyl (OH). 
 
 NITROGEN SUBSTITUTIONS. 
 
 Amines. By substituting for one or more hydrogens 
 in ammonia (NHg) the hydrocarbon radical ethyl (C3H5) 
 we have formed mono-,di-, or tri-ethylamine C3H5NH3 ; 
 (CsHs)^ NH and (C3H5)3N. 
 
 In the same way ethylene amine compounds are formed 
 by replacing the ammonia hydrogens with the compound 
 radical ethylene (C2H4), which has an equivalence of two. 
 Thus ethylene diamine has the formula CgH4(NH3)2 ; di- 
 ethylene diamine, ((Z^Yi^^ (NH)^, etc. 
 
 Amides. By substituting for one of the hydrogens of 
 ammonia the acid radical of acetic acid C3H3 0(OH) we 
 have produced acetamide (CgHgO, NHg), a colorless crys- 
 talline substance with a peculiar odor. In the same way, 
 by substituting the acid radical of oxalic acid, CgOg(OH)2 
 
 240 
 
Organic Chemistry. 241 
 
 (oxalic acid having two replaceable hydrogens, hence di- 
 basic), oxamide (C3 02(NH2)2 is produced. 
 
 PHOSPHOROUS AND METALLIC SUBSTITUTIONS. 
 
 As methyl phosphine (CHgPHg) is formed from phos- 
 phoric acid (HgPO^) by methyl substitutions (see page 
 229), so in the same way is produced by the substitution 
 of ethyl, ethyl phosphine (C3H5PH3), di-ethyl phosphine 
 (CgHg)^ PH., etc. Ethyl, having an equivalence of one, 
 will by uniting with zinc form zinc ethyl, (C2H5)Zn; with 
 arsenic, tri-ethyl ursine (C3Hg)jAs; with mercury, »2^r- 
 cury ethyl {C2lii)2^S-> ^^c. 
 
CHAPTER XII. 
 
 PROPANE COMPOUNDS. 
 
 Propane compounds are those derived from propane 
 (CjHg), which is formed by the union of three hydrocar- 
 bon radicals, thus : 
 
 H H H 
 
 I I I 
 H— C— C— C— H. 
 
 I I I 
 H H H 
 
 Of propane but little is known. It belongs to the 
 CaH^4, series. 
 
 By the extraction of H^ there is produced a compound 
 belonging to the next series C„H:;„ caXleA propine or propy- 
 lene (CgHg) which exists in the form of a gas. By again 
 extracting Hg we obtain a compound belonging to the 
 next series C„Han_^ caWed propine ox allylene (C3H4) which 
 also exists in the form of a gas. As propane is formed 
 by the union of three radicals, it admits of three series of 
 isomeric compounds. 
 
 HALOGEN SUBSTITUTIONS. 
 
 If a halogen element be substituted for hydrogen in one 
 of the hydrocarbon radicals forming propane, propyl com- 
 pounds are produced, the most important of which {■^pro- 
 pyl iodide (C 3 H , I). 
 
 If substituted for the hydrogens in two of the radicals 
 
 242 
 
Organic Chemistry. 243 
 
 the compounds resulting are called propylene, zs propylene 
 /^(jfiiaS? (CjHgIg), and if substituted for the hydrogens in 
 all three radicals we have allylene compounds, as allylene 
 bromide (CgHgBrj). As there are more than one hydrogen 
 in each of the radicals, these compounds thus formed may 
 be mono, di or tri, depending upon the number of hydro- 
 gens replaced. 
 
CHAPTER XIII 
 
 HYDROXYL SUBSTITUTIONS 
 
 As there are three hydrocarbon radicals forming pro- 
 pane and the hydrogens of either one, two, or three may 
 be replaced by hydroxyl, we have formed three sets of 
 alcohols, aldehydes, and acids. In the first set the hydro- 
 gens of only one radical are replaced, in the second set 
 those of two radicals, and in the third set those of all 
 three radicals. Many of these alcohols, aldehydes, and 
 acids are isomeric — having the same chemical formula but 
 differing in their physical and chemical properties. Thus 
 isomerism depends upon the fact that the hydrogens in 
 either of the hydrocarbon radicals forming propane may 
 be replaced by hydroxyl, thus giving the same chemical 
 formula but entirely different substances. Thus, for exam- 
 ple, there are two propyl glycols (alcohols) ; one normal 
 
 OH H OH 
 
 I I I 
 propyl glycol, H — C — C — C — H or CgHgOj ; and isopro- 
 
 H H H 
 
 OH OH H 
 
 I I I 
 pyl glycol, H — C — C — C — H, or CgHgOg, their difference 
 
 H H H 
 
 244 
 
Organic Chemistry. 245 
 
 simply depending upon which radical has its hydrogen re- 
 placed by OH. 
 
 This isomerism is not limited to hydroxyl substitutions 
 but to all substitutions in the hydrocarbon compounds 
 consisting of more than one carbon. In the formation of 
 these three sets of acids, three hydrogens of one hydrocar- 
 bon radical must be replaced by OH, but only one or all of 
 the hydrogens in the other radicals need be thus replaced. 
 
 Thus, for example, in the third set of acids, in which one 
 
 or more of the hydrogens in all three radicals are replaced 
 
 by hydroxyl, three acids are formed, depending upon the 
 
 number of hydrogens replaced as : 
 
 OH OH OH 
 
 I I I 
 1st. Glyceric actd : OH — C — C — C — H. 
 
 I I 1 
 OH H H 
 
 OH OH OH 
 
 III 
 2d. Tartronic acid : OH — C — C — C — OH. 
 
 I i I 
 OH H OH 
 
 OH OH OH 
 
 3d. Misoxal acid : OH— C— C— C— OH. 
 
 I I I 
 OH OH OH 
 
 We now come to the consideration of the first set of 
 
 compounds, in which the hydrogens of only one radical 
 
 are replaced by hydroxyl. The principal alcohol of this 
 
 group is : 
 
 H H OH 
 
 I I I 
 Propyl ALCOHOL : CgHJOH), H— C— C— C— H. 
 
 Ill 
 H H H 
 
246 Organic Chemistry. 
 
 Preparation. It occurs in small amount in the alcoholic 
 fermentation of sugar. 
 
 Properties. It is a liquid with an ether-like odor, easily 
 oxidized into the aldehyde of the first class, — 
 
 H H O 
 
 I I II 
 Acetone or ketone : CgHgO, H — C — C— C + HgO. 
 
 H H H 
 
 Preparation. It is prepared by the dry distillation of 
 sugar, starch, or salts of acetic acid (CgH^Og). 
 
 Properties. It is a colorless liquid with a disagreeable 
 odor, breaking up upon oxidation into formic acid, acetic 
 acid. Thus : 
 
 Acetone. Oxygen. Acetic acid. Formic acid. 
 
 CsHeO +30 = C2H403+CH203. 
 
 H H O 
 
 I I II 
 Propronic acid : CgHgOCOH), H— C— C— C + H2O. 
 
 H H OH 
 
 Occurrence. It is found in the blossoms of plants, and 
 in some animal secretions, as sweat. 
 
 Preparation. It can be prepared by the oxidation of 
 propyl alcohol or by boiling ethyl cyanide (C3H5CN) with 
 potassium hydrate (KOH). 
 
 Properties. Propronic acid is a liquid having the odor 
 and taste of vinegar. It is a mono-basic acid, and forms 
 salts and esters by substituting for the hydrogen basic 
 elements or hydrocarbon radicals. 
 
 Propyl glycol ,C3Hg(OH)2 is an alcohol belonging to 
 the second class, and lactic acid the principal acid. 
 
Organic Chemistry. 247 
 
 ' H OH O 
 
 I I II 
 Lactic acid: C.H50„(0H), H— C— C— C h H„0. 
 
 I I I 
 H HOH 
 
 Occurrence. It occurs in sour milk and in the juices of 
 many plants. It is also the product of lactic fermenta- 
 tion of sugar. 
 
 Preparation. Lactic acid is best prepared by allowing 
 a solution of sugar to stand several days with putrid cheese 
 and chalk. Calcium lactate, Ca(C3H503)3, is formed, 
 which, when acted upon by sulphuric acid (H2SO4), sets 
 free lactic acid. 
 
 Properties. It is a syrupy liquid with a very sour taste. 
 Upon distillation it gives off two molecules of water, 
 forming lactide (CgHgO^). 
 
 Compounds. Lactic acid is mono-basic, and by union 
 with basic elements forms salts as magnesium lactate, 
 Mg(Cg H 503)3 ; potassium lactate, (KCg H 5 O3) ; zinc lactate 
 Zn(C3Hg03)2, etc. By substituting for the hydrogen of 
 the hydroxyl hydrocarbon radicals esters are formed, as 
 ethyl lactic ester {fi ^Yl ^,Q,^\{ ^O ^. By substituting forthe 
 hydroxyl, NHg, we have the formation of lactamide (NHg 
 C3H5O2). 
 
 OHO 
 
 II I II 
 Malonic acid : CgHaOgCOH)^, C— C— C + 2HgO. 
 
 OH H OH 
 
 This is another acid belonging to the second class. 
 It is crystalline, soluble in water, and di-basic in charac- 
 ter, forming, with basic elements, acids and neutral salts. 
 There is but one alcohol of the third class, and that is 
 
248 Organic Chemistry. 
 
 OH OH OH 
 
 I I I 
 Glycerol: C„Hs(OH)„ H— C— C— C— H. 
 
 Ill 
 H H H 
 
 Synonym. Glycerine. 
 
 Occurrence. It is found in nearly all vegetable and 
 animal fats. A little occurs also with the alcoholic fer- 
 mentation of sugar. 
 
 Preparation. It is best prepared by decomposing fats 
 with superheated steam. 
 
 Properties. Glycerine is a colorless syrupy liquid with 
 a sweetish taste, soluble in water, and not easily decom- 
 posed when pure. 
 
 If glycerine is mixed with nitric acid (HNO3) '"^ the 
 presence of sulphuric acid (H2SO4), it forms nitro-glycer- 
 ine ox glycol nitric ester, CgH5(N03)3, a violently explo- 
 sive substance. When this is mixed with infusorial earth 
 it is called dynamite. Fats and oils are glycerol esters of 
 glycerides. 
 
 Acids. There are three acids belonging to the third 
 class, their composition depending upon the number of 
 hydrogens replaced by hydroxyl, none of which, however, 
 are of much importance. 
 
 By substituting hydroxyl for the hydrogen of the un- 
 saturatedhy drocarbon CgHg of the C„H,„ series we get 
 a new group of compounds called allyl, some of which are 
 obtained from allyl iodide, CgHg I. 
 
 H H O 
 
 Allyl alcohol: C3H6(0H), <C— C— C— H. 
 
 H H 
 This is a colorless liquid, with a biting odor and taste. 
 It is combustible, burning with a hot flame. 
 
Organic Chemistry. 249 
 
 H HOH 
 
 i I II 
 Allyl ALDEHIDE or acroline : C3H4O, or <C — C — C 
 
 I I 
 H H 
 
 + H3O. 
 
 This is an oily liquid, with a nasty odor and taste. .It 
 
 readily decomposes. 
 
 H H O 
 
 I i II 
 Acrylic acid : C 3 H 3 0(0 H), < C— C— C + H 3 O. 
 
 H OH 
 
 Acrylic acid is mono-basic, and has a very peculiar, dis- 
 agreeable odor. Its salts are mostly crystalline, the most 
 important of which is sodium acrylate (NaCjHgOg). 
 
 There are two important oils belonging to the allyl 
 compounds — mustard oil and garlic oil. 
 
 Mustard oil, C3H5, NCS is produced from mustard 
 seeds by fermentation. 
 
 It is a clear liquid, having the properties of mustard. 
 
 Garlic oil or allyl sulphide (Cg 115)35 is found in nature 
 in the bulbs of garlics and onions. 
 
 It is a clear liquid, with a garlic-like odor. 
 
CHA.PTER XIV. 
 
 BUTANE COMPOUNDS. 
 
 The next of the hydrocarbon series, with the general 
 formula C„Hj„^-„ is butane {fi^^^, which is a compound 
 of four hydrocarbon radicals expressed thus : 
 
 H H H H 
 
 H— C— C— C— C— H. 
 
 I I I I 
 H H H H 
 
 As the hydrogens in any of these four radicals can be re- 
 placed by halogens, hydroxyl, etc., many of the resulting 
 compounds are isomeric, as butyl chloride (C4HgCl) and 
 isobutyl chloride {C ^Yi ^C\). The halogen substitutions of 
 butane are numerous but unimportant. 
 
 HYDROXYL SUBSTITUTIONS. 
 
 As there were three sets of alcohols, aldehides, and 
 acids formed from propane by hydroxyl substitutions, so 
 there are four sets thus obtained from butane. 
 
 The most important alcohol thus obtained from bu- 
 tane is : 
 
 H H H OH 
 
 I I I I 
 ISOBUTYL ALCOHOL : C4Hj(0H), H— C— C— C— C— H. 
 
 H H H H 
 250 
 
Organic Chemistry. 251 
 
 Occurrence. It occurs in the alcoholic fermentation of 
 sugar but in small amount. 
 
 Properties. It is a clear liquid with a sharp biting 
 taste, and has an odor resembling fusel oil. 
 
 The aldehydes of butane are of little importance, but 
 many of the acids are well known. 
 
 H H H O 
 
 I I I II 
 Butyric ACID: QH,0(OH), H— C— C— C— C+HoO. 
 
 I I I I 
 H H H OH 
 
 Occurrence. It occurs with other acids in butter, in 
 sweat, and in the juices of some plants. 
 
 Preparation. It is prepared from the lactic-acid fer- 
 mentation of sugar by a process similar to that of the 
 preparation of lactic acid, except that the fermentation is 
 allowed to proceed further. 
 
 Properties. Butyric acid is a colorless sour liquid with 
 an odor resembling vinegar. It is mono-basic in charac- 
 ter, forming crystalline salts by its union with basic ele- 
 ments. 
 
 O H H O 
 
 II I I II 
 Succinic acid : (Zj^YiS^^{OYi\, C— C— C— C+2H2O. 
 
 OH H H OH 
 
 Occurrence. This acid occurs in many plants, in some 
 of the animal secretions, and in amber. It is also a 
 product of the alcoholic fermentation of sugar. 
 
 Preparation. It is prepared by the distillation of 
 amber. 
 
 Properties. Succinic acid crystallizes in prisms. It is 
 soluble in water, and has a biting taste. It is di-basic in 
 
252 Organic Chemistry. 
 
 character, forming acid or neutral salts by the replace- 
 ment of one or both hydrogens with basic elements. 
 
 O H H O 
 
 II I I II 
 Malic acid : C4H403(OH)2, C— C— C— C+2H2O. 
 
 OH o'h H oh 
 
 Occurrence. It occurs in many sour fruits, and is usual- 
 ly prepared from the ripe berries of the mountain ash. 
 
 Properties. Malic acid crystallizes at ordinary tempera- 
 tures in solid mass. It is soluble in water and has a very 
 sour taste. It is di-basic in character, forming neutral 
 and acid salts. 
 
 O OH OHO 
 
 II I I II 
 Tartaric acid: C4H404(0H)3, C— C— C— C. 
 
 OH H H OH 
 
 Occurrence. It occurs in many fruits, especially grapes. 
 
 Preparation. Acid tartrates of calcium and potassium 
 occur in solution in young wine, but as the wine grows 
 stronger in alcohol these acid salts, which are insoluble in 
 alcohol, are deposited on the sides of the wine casks. 
 From these masses, called argol or tartar, the tartaric acid 
 is prepared. It is also artificially produced by the action 
 of nitric acid (HNOg) on sugar of milk (Cig^ssOii)* 
 
 Properties. Tartaric acid occurs in crystals, but is 
 easily soluble in water. It has a sour, pleasant taste, and 
 being di-basic forms acid and neutral salts, some of which 
 are very important. Among the most important tartrates 
 ^x& acid potassium tartrate or " cream of tartar " (C4H5- 
 K.O^),potassiumtartrate{Cill^K20f^), and potassium anti- 
 monial tartrate (2KSbO, C4H40g). 
 
CHAPTER XV. 
 
 PENTANE AND HEXANE COMPOUNDS. 
 
 PENTANE COMPOUNDS. 
 
 The next of the saturated series CJi^n+i is pentane 
 or amj/l {C^li^2)> ^"^ consists of the union of five hydro- 
 carbon radicals. There are but few compounds belonging 
 to this group of any importance. Among them are amyl 
 alcohol and valerianic acid. 
 
 H H H H OH 
 
 I I I I I 
 Amyl alcohol: C5Hii(0H), H— C— C— C— C— C— H. 
 
 I I I I 
 
 H H H H H 
 
 Synonym. Fusel oil. 
 
 Occurrence. It occurs in the alcoholic fermentation of 
 sugar, and is separated by distillation. 
 
 Properties. Fusel oil is a colorless liquid with a burning 
 raw taste and disagreeable odor. It is combustible, burn- 
 ing with a hot flame. 
 
 H H H H- O 
 
 I I I r II 
 
 VALERIANIC ACID : CgHgOCOH), H— C— C— C— C— C + 
 
 H H H H OH 
 H^O. 
 
 Occurrence. It occurs in the root of the plant valerian, 
 from which it is prepared, and also in putrid cheese. 
 
 253 
 
254 Organic Chemistry. 
 
 Properties. It is a liquid with the odor of rotten cheese, 
 and is used extensively in medicine. 
 
 It is mono-basic in character, forming salts, the most 
 important of which is zinc valeriancite, Zn (C5HgOg)3. 
 
 Uric ACID : CgH4N403. This acid probably belongs 
 to the pentane group, but is of complicated composition. 
 
 Synonym. Lithic acid. 
 
 Occurrence. It forms a normal constituent of urine, and 
 is usually prepared from the urine of snakes, which is 
 composed almost entirely of uric acid. 
 
 Properties. Uric acid exists in the form of a white 
 crystalline powder slightly soluble in water. It has two 
 replaceable hydrogens, consequently is di-basic in charac- 
 ter, forming neutral and acid salts, the most important of 
 which are sodium urate (CgN^HgNagOg), and acid potas- 
 sium urate (CgN^HgKOg). Uric acid has many deriva- 
 tives. 
 
 HEXANE COMPOUNDS. 
 
 Hexane compounds are not well known or understood. 
 
 There are several important compounds among this 
 
 group, however, as hexyl alcohol or mannite and citric 
 
 acid. 
 
 OHOHOHOHOHOH 
 
 I I I I I I 
 mannite: CgHsCOH)^, H— C— C C— C C— C— H. 
 
 H H H H H H 
 Occurrence. It occurs in large quantities in the vege- 
 table kingdom, especially in " manna," the dried sap of 
 ftaximus ornus. 
 
 Properties. It stands in close relation to sugar. It has 
 a sweet taste, crystallizes in prisms, and is soluble in 
 water. 
 
Organic Chemistry. 
 
 25s 
 
 O O H H H O 
 
 II II I I I II 
 Citric acid: CgHB04(OH)3, C— C— C — C— C— C + 
 
 I I I I I 
 
 OH OH OH HOH. 
 
 3H,0. 
 
 Occurrence. It occurs in many sour fruits, especially 
 the lemon, from which it is prepared. 
 
 Properties. It exists in crystalline masses, which are 
 slightly deliquescent. It is soluble in water, and has a 
 sour, pleasant taste. In solution it readily decomposes. 
 
 It is tri-basic, forming salts, the most important of 
 which are calcium citrate, Caj(CgHgO,)g, magnesium ci- 
 trate, Mg3(CgH50,)3, and ferric citrate, Fe2(CgHgO,)2. 
 
CHAPTER XVI. 
 
 OILS AND FAT3. 
 
 There are many higher hydrocarbon compounds of the 
 C Hjn+a series than hexane, but most of them are un- 
 important. 
 
 There are several acids, however, belonging to these 
 higher series which are of importance, as they occur in 
 oils and fats. These are palmetic acid, Ci8HgjO(OH), 
 stearic acid, CigHggO(OH), both of which are solid at 
 ordinary temperatures, and oleic acid, €18^330(01!), a 
 liquid. 
 
 Fats and OILS are mostly glycerol esters of these 
 acids, and their composition may be represented by 
 substituting for the hydroxyl hydrogen of glycerol, 
 CgHg(OH)3, the acid rests of palmetic, stearic, and oleic 
 acids. 
 
 The following important glycerol esters or fats are thus 
 obtained : 
 
 Palmitin, Q^Yi^{(Z-^i^Yi^^O^^. 
 
 Stearin, Z^Yi^i^Z^^Yi^^O^^. 
 
 Olein, C3Hg(Ci8H330g)3. 
 
 In the vegetable fats olein is the most important and is 
 fluid at ordinary temperatures. It occurs in olive oil, 
 almond oil, cocoa-nut oil, castor oil, croton oil, etc. 
 
 All three of the fats occur in animals. 
 
 Butter is a glyceride or ester of butyl and other acids. 
 
 Saponification. All fats are decomposed by alkalies 
 
 256 
 
Organic Chemistry. 257 
 
 into fatty acids and glycerine. The fatty acids combine 
 with the alkalies to form salts. 
 
 These fatty acid salts of potassium and sodium are 
 called soaps. Soft soap is potash soap, and hard soap is 
 soda soap. 
 
 Spermaceti is the palmetic ester of cetyl alcohol, 
 CieHssCOH). 
 
CHAPTER XVII. 
 
 CARBOHYDRATES. 
 
 Carbohydrates are hydrocarbons, mostly belonging to 
 the hexane compounds, containing hydrogen and oxygen 
 in proportion to form water. 
 
 They may be divided into three groups. The first 
 group, comprising grape sugar, fruit sugar, and galactose, 
 has the general formula CgHj^Og. The second group, 
 comprising cane sugar, lactose, and melitose, has the 
 formula CjgHggOji ; and the third ^ro\x-^, starch, cellu- 
 lose, dextrine, glycogen, and mucilage, the formula 
 
 All the carbohydrates are soluble in water, bend the 
 flame of polarized light, are decomposed by heat, leaving 
 carbon, and converted by oxidation into oxalic acid 
 (C,H,0,). 
 
 Grape sugar, CjHigOg. 
 
 Synonyms : Glucose, dextrose. 
 
 Occurrence. It occurs in nearly all sweet fruits and in 
 honey. 
 
 Preparation. It is made from the fruits, and chemically 
 by boiling cane sugar with dilute acids. 
 
 Properties. Grape sugar as first obtained is a syrupy 
 liquid, but crystallizes on standing. It is soluble in water 
 and has a sweet taste. It turns the plane of polarized 
 light toward the right, and is fermentable. 
 
 When boiled with an alkaline solution of cupric sul- 
 
 258 
 
Organic Chemistry. 259 
 
 phate (CU3SO4), the copper becomes oxidized and is pre- 
 cipitated as the red oxide of copper (CugO). 
 
 This reaction forms a delicate test for the presence of 
 glucose. 
 
 Levulose, CgHj^Og. 
 
 Synonym. Fruit sugar. 
 
 Its occurrence, preparation, and properties are the same 
 as glucose, but can be distinguished from it by turning 
 the plane of polarized light toward the left, and being less 
 easily crystallized. 
 
 Galactose, CeHjgOg. 
 
 Preparation. It is prepared by boiling milk sugar with 
 dilute acids. Its properties are the same as glucose. 
 
 Cane sugar, CigHjgOn. 
 
 Synonym. Saccharose. 
 
 Occurrence. It occurs principally in the juices of sor- 
 ghum, sugar cane, sugar beet, and maple, and is prepared 
 from them by evaporation. 
 
 Properties. It crystallizes, is soluble in water, has a 
 very sweet taste, and polarizes toward the right. 
 
 By heating with dilute acids it takes up water and is 
 converted into glucose. Thus : 
 
 Cane sugar. Water. Glucose, 
 
 CisHa.O.i -f H,0 = 2C6H,30e. 
 
 Lactose, CigHggOn. 
 
 Synonym. Milk sugar. 
 
 Occurrence. It occurs in mammals' milk, from which 
 it is prepared. 
 
 Properties. It crystallizes in rhombic-shaped prisms, is 
 soluble in water, and has a sweet taste, having the general 
 properties of cane sugar. ! 
 
 Starch, CgHjoOg. 
 
 Synonym. Amylum. 
 
26o Organic Chemistry. 
 
 Occurrence. It occurs abundantly throughout the vege- 
 table kingdom, but is found especially in grains and pota- 
 toes, from which it is prepared. 
 
 Properties. It consists of fine white granules, their 
 shape depending upon the kind. It is without taste, and 
 insoluble in cold water. 
 
 It is converted first into dextrine and then into glucose 
 by dilute acids, by dry heat, and by diastase (a ferment in 
 germinating grain). Iodine unites with starch in solution, 
 forming a deep blue color, thus affording a delicate test 
 for amylum. 
 
 Glycogen, CgHj(,Og. 
 
 Occurrence. It occurs in all livers, from which it is 
 prepared. 
 
 Properties. Glycogen is a yellowish-white powder, 
 soluble in water, and changed into glucose by dilute acids 
 and ferments. With iodine it turns a claret color. 
 
 Dextrine, CgHuOg. 
 
 Synonym. British gum. 
 
 Preparation. It is prepared from starch by adding 
 dilute nitric acid (HNO3), and then rapidly drying. 
 
 Properties. Dextrine is an amorphous white substance 
 \ f without anY ^keaction with iodine, soluble in water, and 
 rapidly converted into glucose by means of ferments and 
 acids. 
 
 Cellulose, CigHgoOig. 
 
 Synonyms : Woody fibre, cotton. 
 
 Occurrence. It forms the skeleton and plant cells of 
 wood and plants. 
 
 Properties. As usually prepared it is a white mass, in- 
 soluble in water. When dissolved with sulphuric acid 
 (HgSO^) and precipitated by the addition of water, it is 
 called amyloid. It is this amyloid that gives the peculiar 
 
Organic Chemistry. 261 
 
 appearance to " parchment paper." If cellulose (cotton) 
 be treated with one part nitric acid (HNO3) and three 
 parts sulphuric acid (H^SO^), a violent explosive called 
 gun-cotton, Ci8H3i(NOg)90i5, is formed. 
 
 Gun-cotton dissolved in ether is called collodion, Cu- 
 
 (N03)8H3,0,5. 
 
 Glucosides. There is a large number of substances 
 occurring in the vegetable kingdom closely allied to the 
 carbohydrates, called glucosides. They are usually com- 
 pounds of dextrose, combined with one or more other 
 organic substances. 
 
 By boiling with dilute acids, alkalies, or by ferments 
 they split up into sugar and the other constituents of 
 which they are composed. 
 
 Amygdalin, CjoHg^NOn, is the glucoside found in 
 bitter almonds, cherry and peach pits, etc., and can be 
 split up by the ferment — emulsion — into its constituents, 
 dextrose, hydrocyanic acid, and benzaldehyde. Thus : 
 
 Amygdalin. Water. Sugar. Hydrocyanic acid, Benzaldehyde. 
 
 QoH2,NO„+2H30 = 2CeH,20,+HCN + C,HeO. 
 
CHAPTER XVIII. 
 
 FERMENTATION. 
 
 Some substances, when undergoing decomposition or 
 decay, have the property of setting up decomposition in 
 other substances when added to them. The decaying 
 substance is called 2u ferment, the substance decomposed 
 fermentable, and the process fermentation. 
 
 Different ferments set up different kinds of fermenta- 
 tion, but do not themselves add any elements to the pro- 
 ducts of fermentation. 
 
 If the products of fermentation are sweet-smelling, the 
 process is called pure fermentation ; but if accompanied 
 by foul odors, putrefaction. 
 
 Ferments are of two kinds, decomposable organic com- 
 pounds and organized bodies. Belonging to the first class 
 are albuminous substances as diastase, a substance formed 
 from germinating grain from the decomposition of 
 glutin ; emulsin a substance occurring in almonds ; and the 
 animal ferments occurring in animal secretions, as saliva, 
 pancreatic and gastric juices, etc. 
 
 Belonging to the second class of organized ferments are 
 the yeast plant lactic-acid ferment, etc. As most fer- 
 ments are vegetable growths, they must be supplied with 
 proper food for their development. This food is found in 
 the albuminous principles occurring in the fermentable 
 substance. 
 
 Most ferments require for their development oxygen, 
 
 S63 
 
Organic Chemistry. 263 
 
 and a temperature between 40° and 90° F. Some sub- 
 stances undergo spontaneous fermentation, but this is due 
 to the sporules or seeds of the ferment which float in the 
 air finding their way into these substances and then 
 propagating. 
 
 There are five principal fermentations — alcoholic, acetic, 
 lactic, butyric, and inucous, the most important of which is 
 the alcoholic. The alcohol ferment is yeast, the ferment- 
 able substance sugar, and the principal products of fer- 
 mentation, alcohol and carbonic-acid gas. Thus : 
 
 Sugar. Alcohol. Carbonic acid. 
 
 CeH.gOe = 2C3Hb(OH) -f 2CO3. 
 
 ALCOHOLIC BEVERAGES. 
 
 Beer is prepared from germinating grain, usually barley. 
 During this process, called malting, a ferment, diastase, is 
 produced, which acts on the starch of the grain, converting 
 it into sugar. Hops are added to give it flavor, and yeast 
 to produce the alcoholic fermentation. The fermentation 
 is never allowed to run its full course. Porter, ale, and 
 stout are very similar to beer, but differ in the rapidity, 
 temperature, and time of fermentation, and porter by con.* 
 taining caramel. 
 
 Wine is made from fermented grape juice, which will 
 undergo spontaneous fermentation if exposed to the air, 
 owing to the presence of vegetable albumen, which un- 
 dergoes decomposition and acts as a ferment on the grape 
 sugar. Effervescent wines are bottled before fermentation 
 is completed Dry or acid wines contain but little or no 
 unchanged sugar. 
 
 During fermentation of grape juice, argol, or acid potas- 
 sium tartrate, is deposited on the sides of the casks, 
 owing to the fact that this salt is insoluble in the alcohol 
 
264 Organic Chemistry. 
 
 which is being produced, but found in solution in the 
 grape juice. 
 
 Whiskey and Spirits are usually made from grain, but 
 a large quantity of raw grain is added to germinating grain 
 or malt, the diastase converting the starch into sugar. 
 Fermentation is pushed as far as possible with yeast and 
 the product distilled. 
 
CHAPTER XIX. 
 AROMATIC GROUP. 
 
 BENZINE. 
 
 As the fatty group of compounds was derived directly 
 or indirectly from methane benzene (CH^), so has the 
 aromatic group also a starting-point in benzine (CgHg). 
 
 Benzine is supposed to belong to the unsaturated group 
 of hydrocarbons having the general formula QH^_6, and 
 graphically expressed by the chain or ring formula 
 
 H 
 
 I 
 H C H 
 
 C C 
 
 II I 
 H— C C— H 
 
 \/^ 
 C 
 
 I 
 H 
 
 As one or more hydrogens in methane can be replaced 
 by halogens, hydroxyl, acid radicals, amidogen, etc., so 
 may the hydrogens in benzine be likewise replaced. It is 
 a curious fact, however, if only one hydrogen in benzine 
 be thus replaced by elements or atomic groups, but one 
 compound can be formed, in other words one hydrogen 
 substitution allows of no isomerism. This does not hold 
 
 s6s 
 
266 Organic Chemistry. 
 
 true, however, if two or more hydrogens be thus re- 
 placed. 
 
 Benzine, CgHg. 
 
 Synonym. Benzol. 
 
 Preparation. All organic compounds heated to a red 
 heat yield benzine ; hence it is formed in the manufacture 
 of illuminating gas, and obtained from the coal tar by 
 distillation. 
 
 Properties. Benzine is a clear liquid with an aromatic 
 odor and taste. It has a low boiling point, and is readily 
 combustible, burning with a very smoky yellow flame. 
 
 It has strong refractive properties, and is used in the 
 manufacture of aniline and aniline colors. 
 
CHAPTER XX. 
 BENZINE DERIVATIVES. 
 
 It is not necessary to point out a great many of the 
 benzine derivatives but a comparatively few of them be- 
 ing of much importance. We have already seen that one 
 or more of the benzine hydrogens may be replaced by 
 halogen elements, hydroxyl, amidogen, acid radicals, hy- 
 drocarbon radicals, etc., hence it will be but necessary to 
 consider the most important of these compounds thus 
 formed by substitution. 
 
 There are but few HALOGEN SUBSTITUTIONS of import- 
 ance, and among them may be mentioned mono-chlor-ben- 
 zine (CgHgCl) and mono-iodo-benzine (CgHjI). Among 
 the most important ACID DERIVATIVES of benzine is nitro 
 benzine (C^Hg, NOg), formed by replacing the acid radical 
 of nitric acid (the acid minus hydroxyl) for one benzine, 
 hydrogen. It is prepared by adding nitric acid (HNO3) 
 to benzine and then precipitating the nitro-benzine by 
 water. Thus produced it is a heavy yellow oil with a 
 pleasant odor — used in perfumery under the name of oil 
 of merbane. 
 
 HYDROXYL SUBSTITUTIONS. 
 
 There are many important hydroxyl substitutions in 
 benzine, and the compounds thus produced are called 
 phenols. 
 
 Carbolic acid, CgHgOH. 
 
 Synonyms : Phenol, hydroxyl benzine. 
 
 267 
 
268 Organic Chemistry. 
 
 Occurrence. It is one of the principal constituents of 
 coal tar, from which it is prepared. 
 
 Properties. Carbolic acid crystallizes in clear needles, 
 but gradually turns red on exposure to the light. It has a 
 peculiar dead smell, a sweetish taste, and caustic proper- 
 ties. It is slightly soluble in water, readily in glycerine. 
 
 Uses. It is used in medicine as a disinfectant, and in 
 the production of aniline colors. Although phenol is 
 really an alcohol it also acts as a mono-basic acid, uniting 
 with basic elements to form salts and with alcohol rests to 
 form esters with the replacement of hydrogen. 
 
 Thus we have sodium pkenate,C^Y{ ^l^a.O, lead phenate, 
 (CeH50)3Pb, phenyl ethyl ester, CgHgO, CgHg, etc. If 
 three of the benzine hydrogens are replaced by the acid 
 radical NOg and one of the hydrogens by hydroxyl OH, 
 there is formed PICRIC ACID, C6H2(N02)30H. 
 
 Picric Acid, C8H2(N03)30H. 
 
 Synonym. Tri-nitro-phenol. 
 
 Preparation. It is prepared by heating phenol with ni- 
 tric acid (HNO3). 
 
 Properties. Picric acid crystallizes in yellow leaves. It 
 is soluble in water and has a very bitter taste. It forms 
 salts with basic elements, the most important of which is 
 potassium pier ate, CgH2(N03)gKO. 
 
 Uses. It is used for dyeing purposes. 
 
 If three benzine hydrogens are replaced by hydroxyl 
 several isomeric compounds are produced, the most im- 
 portant of which is pyrogallic acid, CgH3(OH)3, a crystal- 
 line white substance soluble in water and with a bitter 
 taste. It is a good oxydizing agent. 
 
 AMIDOGEN SUBSTITUTIONS. 
 
 Among the most important amidogen derivatives of 
 benzine is aniline. 
 
Organic Chemistry. 269 
 
 Aniline, CgHgNHg. 
 
 Synonym. Amido-benzine. 
 
 Occurrence. It occurs largely in coal tar. 
 
 Preparation. It may be prepared in a number of ways, 
 as by the dry distillation of indigo from coal tar by igni- 
 tion, etc., but it is generally made by reducing nitro-ben- 
 zine(CgHgNOg)with iron filing and acetic acid {(Z^^J^^, 
 the reduction being thus represented : 
 
 Nitro-benzine. Hydrogen, Aniline. • Water, 
 
 CeHgNOa ^ 3H, = CeHgNHa + 2H,0. 
 
 Properties. Aniline is a yellowish liquid turning brown 
 on exposure to the light. When brought in contact with 
 calcium hypochlorite Ca(C10)g, it turns a violet color. It 
 unites with acid to form salts. 
 
 One or both of the amido-hydrogens may be replaced 
 by hydrocarbon radicals, forming compound anilines, as 
 ethyl aniline (Cg H g , NH, Cg H 5) ; or by acid rests as CHO, 
 the acid rest of formic acid CHO(OH), forming anilides, 
 Sisformanilide (CgHg, NH, CHO). 
 
 Uses. It is used principally in the manufacture of ani- 
 line colors and dyes. 
 
 NITROGEN SUBSTITUTIONS. 
 
 Azo-BENZINES. If hydrogen benzine be replaced by 
 nitrogen we have formed a group of compounds called 
 azo-benzines. The most important of these compounds are 
 azo-benzine,{^i^Yi^^'^, diazo-benzine, CgHgNg zxvd. diazo- 
 benzine nitrate, CgHgNjNOg, which is produced by the 
 action of nitrous and nitric acid on amido-benzine. Thus : 
 
 Amido-benzine. Nitric acid. Nitrous acid, 
 
 CgHgNHj 4- HNO3 + HNO3 = 
 
 Diazo benzine nitrate. Water, 
 
 CgHgNgNOs + 2Hs,0. 
 
270 Organic Chemistry. 
 
 This is a crystalline substance, decomposing with ex- 
 plosive violence on exposure to heat or percussion. 
 
 INDIGO GROUP. 
 
 There is a class of compounds called the indigo group, 
 which are benzine derivatives but of complex composi- 
 tion. This, group starts from a glucoside called indican, 
 which occurs in a number of plants. This substance, 
 when boiled with acids, decomposes into sugar and indigo 
 white, and the latter, by exposure to the air, turns into 
 indigo blue. 
 
 Indigo blue, CigHmNgOg. 
 
 Preparation. It is best obtained in the pure state from 
 commercial indigo, which consists of a number of sub- 
 stances, by sublimation. 
 
 Properties. Indigo blue is a blue, odorless, and taste- 
 less powder, insoluble in water and alcohol. 
 
 When heated with alkalies in presence of reducing 
 agents, as sulphuretted hydrogen (HgS), it takes up hy- 
 drogen and passes into a soluble and colorless substance 
 called indigo white {(Z^^^Yi^^'^ ^O ^, which is largely used 
 in indigo dyeing. On exposure to the air indigo white is 
 slowly converted into indigo blue. Indigo blue, when 
 treated with oxidizing agents, as nitric or chromic acid, 
 takes up oxygen and is converted into isatin (CigHmNg- 
 O4), which exists in the form of reddish-brown, odorless 
 prisms, slightly soluble in water, but readily in alcohol. 
 
 Both indigo blue and isatin when treated with potassium 
 hydrate (KOH) are converted into aniline. 
 
CHAPTER XXI. 
 HYDROCARBON SUBSTITUTIONS OF BENZINE. 
 
 If one or more of the benzine hydrogens are replaced 
 by hydrocarbon radicals a number of important com- 
 pounds are formed and among them is : 
 
 Toluene: CgHg, CH3. 
 
 Synonym. Methyl benzine. 
 
 Preparation. It may be prepared by heating organic 
 compounds to a high temperature and then distilling, or 
 chemically by heating mono-brom-benzine and methyl 
 iodine with sodium. Thus : 
 
 Mono-benzine. Melh. iod. Sodium. Toluene. Sod. bromide. Sod. iodide. 
 
 CaHsBr + CHgl + Nag = CgHg, CH3 + NaBr + Nal. 
 
 Properties. Toluene resembles benzine in all its prop- 
 erties. 
 
 BENZYL compounds. 
 
 One or more of the hydrogens in toluene may be re- 
 placed by halogens, hydroxyl, amidogen, etc., thus form- 
 ing an enormous number of new compounds, but the most 
 important of which are those formed by replacing the hy- 
 drogen of the hydrocarbon radical in toluene ; such sub- 
 stitutions are called benzyl compounds. By thus replacing 
 one hydrogen with chlorine we have formed benzyl-chlo- 
 ride{C^l[i^, CH3CI); with hydroxyl, benzyl alcohol {C^Yi^, 
 CH3OH), etc. 
 
 Benzyl alcohol: CgHg, CHg(OH). 
 
 271 
 
2/2 Organic Chemistry. 
 
 Preparation. It is prepared by treating benzyl chloride 
 with potassium hydrate. Thus : 
 
 Benzyl chlor. Pot. hydrate. Benzyl alcohol. Pot. chlor. 
 
 CsHj, CHgCl + KOH = CgHg, CH^COH) + KCl. 
 
 Properties. Benzyl alcohol is a colorless liquid with a 
 pleasant odor. It forms esters by replacing the hydroxyl 
 hydrogen with acid rests, as benzyl acetic ester (C5H5, 
 CH.3O, C2H3O), etc. 
 
 If two hydrogens in toluene instead of one be replaced 
 by hydroxyl, a molecule of water is given off and benzyl 
 aldehide is formed. 
 
 Benzyl aldehide : CgHg, CHO. 
 
 Synonyms: Benz-aldehide, bitter almond oil. 
 
 Preparation. It is prepared from a glucoside, occurring 
 in bitter almonds, called amygdalin. 
 
 Properties. It is a colorless liquid with the odor and 
 taste of bitter almonds. It is not poisonous, as the hydro- 
 cyanic acid (HCN) occurring in bitter almonds is elimi- 
 nated by the process of preparation. If three hydrogens 
 in toluene be thus replaced by hydroxyl, benzoic acid is 
 produced, a molecule of water being given off. 
 
 Benzoic acid: CgHj, CO(OH). 
 
 Occurrence. It occurs in many gums, from which it is 
 prepared by sublimation. 
 
 Properties. Benzoic acid crystallizes in colorless leaf- 
 lets, slightly soluble in water, and with an aromatic taste 
 and odor. It is mono-basic in character, uniting with 
 bases to form salts, as sodium benzoate, CgHgCOgNa. 
 
 BENZOIC-ACID COMPOUNDS. 
 One or more hydrogens in benzoic acid, (CgHgCHOg) 
 may be replaced by chlorine amidogen, hydroxyl, etc., 
 thus forming a new set of compounds, many of which are 
 
Organic Chemistry. 273 
 
 important. Thus, if one hydrogen is replaced by chlorine, 
 we have ntono-chlor -benzoic acid (CgH^Cl, CHO3) ; by 
 NOg, nitro-benzoic acid (CgH^NOg.CHOg); byNHg ami- 
 do-benzoic acid (CgH4NH2, CHOg); by OH, salicylic acid 
 (CgH^OH, CHOg), etc. 
 
 Salicylic acid: C6H4(0H), CO(OH). 
 
 Occurrence. It occurs as a principal constituent of 
 winter-green oil. 
 
 Preparation. It is prepared from carbolic acid (CgHg- 
 OH) by heating it with sodium, and then passing carbon 
 dioxide through the mixture. In this way sodium 
 salicyliate (C8H4NaO, CONaO) is also produced. Thus : 
 
 Carbolic acid. Sodium. Garb, dioxide. Sod. salicyliate. Hydrogen. 
 
 CgHgOH + 2Na + CO2 = CgH^NaO, CONaO + 2H. 
 
 Properties. Salicylic acid crystallizes in prisms, which 
 are slightly soluble in water, and have a bitter taste but 
 no smell. It acts either as a mono- or di-basic acid uniting 
 with alkalies, with the replacement of both hydrogens, as 
 sodium salicyliate (CgH^NaO, CONaO). 
 
 Uses. It is used principally as an antiseptic, and in 
 medicine. 
 
 If three of the benzine hydrogens in benzoic acid are 
 replaced by hydroxyl, gallic acid is formed. 
 
 Gallic acid, C5H3(0H)3CH02. 
 
 Preparation. It is usually prepared from its ester, tannic 
 acidifl^^Yi^^O^). 
 
 Properties. Gallic acid crystallizes in fine needles, is 
 soluble in water, and has a very bitter astringent taste. 
 
 Although it usually acts as a mono-basic acid, any or 
 all of the four hydroxyl hydrogens may be replaced by 
 basic elements forming salts. 
 
 Tannic acid is an important ester of gallic acid. 
 
 Tannic acid, C14H10O9. 
 
274 Organic Chemistry. 
 
 Synonym. Tannin. 
 
 Occurrence. It occurs in many plants, as nut-galls, su- 
 mach, etc., from which it is usually prepared by extraction 
 with alcohol and ether. 
 
 Properties, Tannin is freely soluble in water, has a very 
 bitter taste, and is astringent. Animal skins precipitate 
 tannin from its solution, converting them into leather. 
 
 HiPPURIC ACID, CjHgNOg. 
 
 Occurrence. This acid is of complex composition, but 
 is a derivative of benzoic acid. It occurs in the urine of 
 herbivora, and is the result of eating substances rich in 
 benzoates. 
 
 Properties. Hippuric acid crystallizes in needles, and is 
 but slightly soluble in water. 
 
 It has a salty, bitter taste, and is mono-basic in char- 
 acter. 
 
 We have so far considered only the hydrocarbon deriv- 
 atives of benzine in which one hydrogen has been replaced. 
 
 Not only may one hydrogen be thus replaced, but 
 hydrocarbon radicals may be substituted for two, three, 
 or four hydrogens, each forming a new set of compounds. 
 But few of these compounds are of importance, many of 
 them either not being understood or are unknown. 
 
 Those compounds resulting from the substitution of 
 hydrocarbon rests, forming benzine derivatives with eight 
 carbon atoms, are called XYLENES, from xylene, C8H4- 
 (CHg)^ ; those forming benzine derivatives with nine 
 carbon atoms, CUMENS, from cumene, CgH3(CH3)3 ; and 
 those containing ten carbon atoms, CYMENES, from cymene, 
 
 C6Hg(CH3)4. 
 
 There are two cumene compounds which deserve atten- 
 tion, viz. : cinnyl alcohol and cinnamic acid, formed by re- 
 
Organic Chemistry. 275 
 
 placing one of the hydrogens in benzine with allyl alcohol 
 (C3H5OH), and acrylic acid C3H3O, (OH) radicals re- 
 spectively. 
 
 Cynnal alcohol : CgHg, C3H4(OH.) 
 
 Synonym. Phenol allyl alcohol. 
 
 Properties. It is a colorless oil, which gradually, upon 
 standing, crystallizes into needles. It is but slightly solu- 
 ble in water, and upon oxidation is converted into CIN- 
 NAMIC ALDEHYDE (CgHg, C3H3O), a Colorless liquid, 
 prepared from cinnamon oil, which contains it largely. 
 
 CiNNAMIC ACID : CgHg, C3H20(OH). 
 
 Occurrence. It occurs in liquid storax, and is separated 
 from it by heating with sodium carbonate (NagCOg). It 
 also occurs in old cinnamon oil, probably from oxidation 
 of cinnamic aldehyde. 
 
 Properties. Cinnamic acid crystallizes in prisms, which 
 are soluble in water, and have a bitter taste and pleasant 
 odor. It has one replaceable hydrogen, hence is mono- 
 basic, uniting with bases to form salts, and with hydro- 
 carbon rests to form esters. 
 
CHAPTER XXII. 
 
 AROMATIC GROUPS OF ORGANIC COMPOUNDS. 
 
 We come now to the consideration of a number of im- 
 portant aromatic groups of compounds, some having their 
 composition well known, while others have constitutions 
 not known with certainty. 
 
 NAPHTHALINE GROUP. 
 
 This group has its starting-point in naphthaline (Ci „ Hg), 
 
 a substance occurring largely in coal tar. In composition 
 
 it is a compound benzine — that is, formed by the union of 
 
 two benzine rings. Thus : 
 
 H H 
 
 I I 
 
 C C 
 
 /\ / \ 
 H— C C C— H 
 
 I II I 
 
 H— C C C— H 
 
 \ / \/ 
 
 c c 
 
 I .1 
 
 H H 
 
 It crystallizes in white leaflets, and has a peculiar odor 
 and hot taste. It is but slightly soluble in water, but 
 readily in alcohol. 
 
 One or more hydrogens may be replaced by halogens, 
 acid radicals, hydroxyl, etc., thus forming naphthaline 
 
 876 
 
Organic Chemistry. 277 
 
 derivatives. The hydroxyl derivatives are called naphthols 
 from naphthol, CioH,(OH). 
 
 Anthracine group is derived from anthracine 
 (Ci4Hjg), a substance also .occurring largely in coal tar. 
 It crystallizes in leaflets and is but slightly soluble in 
 water. 
 
 Alizarin group has its starting-point in alizarin 
 (C14H8O4), a coloring matter obtained by fermenting the 
 madder root and other plant roots. 
 
 It crystallizes in yellowish prisms, is insoluble in water, 
 but readily in alkaline solution, from which it is precipi- 
 tated by basic elements forming salts. It is used exten- 
 sively in dyeing. 
 
 Camphor group. Common camphor (C^oHigO) is 
 the principal member of this group, and is obtained from 
 the gum of the camphor tree. It is a gum-like substance, 
 slightly soluble in water and readily in alcohol. It has a 
 pleasant and burning taste, is combustible, burning with 
 a very smoky, yellow flame. It unites directly with bro- 
 mine without the replacement of hydrogen, forming 
 brom-camphor (CioH^gBrgO). 
 
 Turpentine group. To this group belongs the essen- 
 tial o\\,\i2.v\n^ the composition CipHjg. They are ob- 
 tained from plants by steam distillation, and are usually 
 divided into two groups, those containing oxygen and 
 those free from oxygen. Among the former are caraway 
 oil, clove oil, rue oil, rose oil, bitter-almond oil, anise oil, etc. 
 while among the latter are lemon oil, orange oil, turpentine 
 oil, amber oil, etc. There are also three essential oils con- 
 taining sulphur, viz., mustard oil, spoonwort oil, and leek 
 oil. 
 
 Resin Group. Resins are obtained from plants, to- 
 gether with the essential oil. If they remained dissolved 
 
278 Organic Chemistry. 
 
 in the essential oils they are called balsams, but if mixed 
 with gum they are known simply as resins. Among the 
 principal balsams may be mentioned copaiba balsam, peru 
 balsam, tolu balsam, and shellac. 
 
 Caoutchouc, or "india-rubber/' is one of the principal 
 resins. It is obtained from the juice of trees growing in 
 India. When heated with sulphur it becomes " vulcan- 
 ized," which renders it more elastic even when cold. On 
 higher heating it is converted into " vulcantine " or " hard 
 rubber." Gutta-percha is a resin like india-rubber and 
 obtained in the same way. 
 
 Amber and asphalt are called the hard or "fossil" 
 resins. 
 
CHAPTER XXIII. 
 
 ALKALOIDS. 
 
 Alkaloids are nitrogenous substances occurring in plants 
 and sometinaes called organic bases on account of their 
 strong basic properties. They are almost insoluble in 
 water but freely soluble in alcohol. They give soluble 
 salts with acids. The alkaloids are precipitated from 
 solutions of their salts with alkalies and tannic acid. 
 
 All the alkaloids contain carbon, nitrogen, and hydro- 
 gen ; some with, others without, oxygen. When no oxy- 
 gen is present the alkaloids are liquids, but with oxygen 
 they are mostly solid and crystalline. 
 
 Alkaloids are prepared by treating the powdered plants 
 containing them with weak acids, and then distilling if the 
 alkaloids are volatile. If not, the alkaloid bases are pre- 
 cipitated with alkalies from their acid solution. 
 
 The alkaloids all have a powerful action on the animal 
 organism, hence are mostly poisonous and are used 
 largely as medicines. 
 
 The following is a list of the most common alkaloids : 
 
 Conine, CgH^^N, exists already formed in the 
 hemlock. 
 
 Nicotine, CjoHj^Ng, is obtained from tobacco leaves. 
 
 Morphine, Ci,Hi9N03, 
 
 Codeine, CigHgiNOj, and 
 
 Narcotine, C23H33NO,, are all obtained, with eigh- 
 teen ornineteen others, from the juice of the poppy (opium). 
 
 279 
 
28o Organic Chemistry. 
 
 Quinine, C2oH24N20g, is obtained, with three or four 
 other alkaloids, from the bark of the cinchona tree. 
 
 Strychnine, CgiH^gNgOg, and Brucine, CjsHggN 
 N3O4, are both obtained from the seeds of the strychnos 
 nux vomica. 
 
 Atropine, Cj^HgjNOg, is found in the deadly night- 
 shade. 
 
 Aconitine, C3oH4,NO,, is found in the root of the 
 purple monk's hood. 
 
 Eserine, Ci5HgiN302,and 
 
 Physostygmine are both obtained from the calabar 
 bean. 
 
 Cocaine, Ci,H3iN04, occurs in the leaves of the 
 cocoa. 
 
CHAPTER XXIV. 
 ANIMAL CHEMISTRY. 
 
 There are a number of complex substances, many of 
 them with unknown composition, occurring in animal tis- 
 sues and fluids, and are hence usually described under the 
 head of animal chemistry. 
 
 The organic compounds all contain oxygen, nitrogen, 
 carbon, and hydrogen, and some of them sulphur. 
 
 As these substances are properly treated of under 
 physiology, a mere mention of them will be given here. 
 
 Among these substances are albumen, fibrin, casein, etc., 
 and may be classified under the following divisions : 
 
 INORGANIC SUBSTANCES. 
 
 Water, HgO. 
 Sodium chloride, NaCl. 
 
 phosphate, Na2HP04. 
 " bi-phosphate, NaHgPO^. 
 " sulphate, Na3S04. 
 " carbonate, Na^COg. 
 Potassium chloride, KCl. 
 
 phosphate, K3HPO4. 
 " carbonate, K3CO3. 
 
 sulphate, k3S04. 
 Calcium phosphate, Ca3(P04)2. 
 " carbonate, CaCOg. 
 
 281 
 
282 Organic Chemistry. 
 
 Magnesium phosphate, Mg^{VOi)^. 
 " carbonate, MgCOg. 
 
 Besides these inorganic principles, there are always 
 found in larger or smaller amount, in the animal tissues 
 and fluids, traces of iron, silica, and fluorine ; these also are 
 constant constituents. 
 
 HYDROCARBONS. 
 
 Glycogen, CeHmOg. 
 Glucose, CgHigOg. 
 Lactose, CgHj^Oe- 
 
 FATS. 
 
 Stearin, C3H5(Ci8H3g02)3. 
 
 Palmatin^ C3Hg(CieH3i02)j. 
 
 Olein, C3H5(Ci8H3302)3. 
 
 Cholesterin, C^^^^J^- 
 
 Cholesterin is a crystalline substance found principally 
 in the bile, from which it sometimes crystallizes, forming 
 gall-stones. 
 
 It is also found in the blood, spleen, nerves, etc. 
 
 ALBUMINOUS PRINCIPLES. 
 
 These form an important group of substances found 
 in the animal body, and all present the following 
 peculiarities: First, they are hydroscopic; second, they 
 are coagulable ; and third under favorable circumstances 
 they vixyA^x^o putrefactive changes. 
 
 Albumen, found principally in the plasma of the blood. 
 
 Casein, an albuminous principle in milk. , 
 
 Fibrinogen, found in blood plasma. 
 
 Paraglobulin, obtained from the blood. 
 
Organic Chemistry. 283 
 
 Myosint is obtained from muscular tissue, and causes 
 " rigor mortis " by coagulation after death. 
 
 Syntonin, or acid albumen, produced by the action of the 
 gastric juice on albumen. 
 
 Peptone, produced by the further action of gastric juice 
 on albuminous matter. 
 
 Mucosine or " mucus," found in many glandular secre- 
 tions. 
 
 Collagin, found in bones, tendons, etc., and yields 
 " gelatine " on boiling. 
 
 Chondrine, albuminous principle in cartilage. 
 
 Elasticine, from yellow elastic tissue. 
 
 Keratine, an albuminous substance containing sulphur; 
 found in hair, nails, etc. 
 
 ANIMAL FERMENTS. 
 
 There are^substances that seem to cause by their 
 presence catflytic transformations, that is, they produce 
 changes in substances in which they come in contact, 
 without entering into chemical combination with them. 
 
 Ptyalin, ferment of the saliva. 
 
 Pepsin is the gastric-juice ferment. 
 
 Pancreatin and trypsin, the pancreatic ferments. 
 
 Fibrin or blood ferment causing the coagulation of the 
 blood. 
 
 ANIMAL COLORING MATTERS. 
 
 Hemoglobin, the coloring matter of the blood. 
 Melanin, that of the skin, eyes, etc. 
 Bilirubin and Biliverdin, that of the bile, and 
 Urochrome, the coloring matter of the urine. 
 
 CRYSTALLIZABLE NITROGENOUS MATTER, 
 These substances differ from the albuminous principles 
 by being crystallizable. They are : 
 
284 Organic Chemistry. 
 
 Lecithin, found in the blood, liver, etc. 
 
 Cerebrin, obtained principally from the brain and spinal 
 cord. 
 
 Leucin, found largely in the spleen. 
 
 Sodium glycocholate and sodium taurocholate are both 
 ingredients of the bile. Creatin, found principally in 
 muscular tissue. 
 
 Creatinine, urea, urates, and hippurates are all found in 
 the urine, and are the result of tissue metamorphosis. 
 
INDEX. 
 
 Abexratioiif achromatic •47 
 
 " spherical, of lenses . 42 
 
 " ^^ " mirrors . 38 
 
 Absorbing hygrometers . . .25 
 Absorption spectra . . . 46 
 
 Accurate thermometers . . .18 
 
 Acetamide 225, 240 
 
 Acetates 237 
 
 Acetic acid 237 
 
 Acetone 246 
 
 Acetylene 232 
 
 ** series 211 
 
 Achromatic aberration . . '47 
 
 " lenses . . . - 47 
 
 Acids, formation of , . . . 216 
 
 Acid molecules 104 
 
 Aconitine 2S0 
 
 Acroline 249 
 
 Acrylates . . ... 249 
 
 Acrylic acid 249 
 
 Adhesion ,5 
 
 Air barometers 12 
 
 ** pumps 13 
 
 " " Sprengers . . . .13 
 " thermometers . . . .17 
 
 Albumen 282 
 
 Alcohol 234 
 
 " thermometers . . . .17 
 Alcohols, formation of . . . 216 
 Aldehydes, *» •* ... 216 
 
 Alizurin 277 
 
 Alkaline earths 175 
 
 ^* metals 170 
 
 Alkalamine, allatropic. . . . 142 
 
 Alkaloids 279 
 
 Allyl alcohol 24S 
 
 " aldehyde 249 
 
 " sulphide 249 
 
 Allylene 
 
 " compounds 
 Alum 
 Aluminum 
 
 *' compounds 
 Almalgams 
 Amides . 
 Amido-benzines . 
 Amidogen 
 Amines . 
 Ammonia 
 
 " amalgam 
 type 
 Ammonium . 
 
 *^ compounds 
 Ampere . 
 Ampdre*s law 
 Amygdalin . 
 Amyl alcohol 
 Amylum 
 Analyser 
 Analysis 
 
 " spectrum 
 
 Aneroid's barometer 
 
 Angle, critical 
 
 *' of deviation 
 
 *' *' incidence in reflection 
 
 " " " " refraction 
 
 ** " reflection 
 
 ** *' refraction 
 
 Aniline .... 
 
 *' derivatives 
 Animal chemistry 
 
 " economy . 
 
 " coloring matters 
 
 *^ ferments . 
 Anode .... 
 Anthracine . 
 Antimony 
 
 " acids of 
 
 24a 
 243 
 19s 
 X9S 
 19s 
 187 
 225 
 269 
 224 
 224 
 
 I2S 
 lOI 
 
 173 
 70 
 194 
 
 261 
 
 253 
 259 
 
 55 
 
 91 
 
 45 
 
 12 
 
 40 
 
 40 
 
 36 
 
 39 
 
 36 
 
 39 
 
 . 269 
 
 269 
 
 281 
 
 . 140 
 
 283 
 
 283 
 
 76 
 
 277 
 
 203 
 
 204 
 
 285 
 
286 
 
 Index. 
 
 Antimony, oxides of . 
 
 
 
 204 
 
 Apparatus induction . 
 
 
 
 84 
 
 Aqua regia . 
 
 
 
 128 
 
 Aroliglit 
 
 
 
 70 
 
 Arcliimedes, law of 
 
 
 
 6 
 
 Argol .... 
 
 
 
 252 
 
 Aromatic group . 
 
 
 
 265 
 
 Arsenic .... 
 
 
 
 199 
 
 " acids of . 
 
 
 
 200 
 
 " compounds 
 
 
 
 199 
 
 *' oxides of . 
 
 
 
 200 
 
 Arsenious acid 
 
 
 
 201 
 
 " oxide 
 
 
 
 200 
 
 Artiad radicals 
 
 
 
 104 
 
 Artiads .... 
 
 
 
 qS 
 
 Artificial magnets 
 
 
 
 58 
 
 Astatic needle 
 
 
 
 SO 
 
 Astronomical telescope 
 
 
 
 48 
 
 Atliermanic bodies 
 
 
 
 26 
 
 Atomic weigiit 
 
 
 
 97 
 
 Atomicity 
 
 
 
 94 
 
 Atoms .... 
 
 
 
 4 
 
 " forces controlling 
 
 
 
 5 
 
 Atmosphere . 
 
 
 
 123 
 
 Atropine 
 
 
 
 280 
 
 Axis, principal, of mirrors 
 
 
 
 37 
 
 " secondary, of mirrors 
 
 
 37 
 
 Azo-benzines 
 
 
 269 
 
 B 
 
 Baking-powder 171 
 
 Balsams .... 
 
 
 . 278 
 
 Barium .... 
 
 
 . .176 
 
 " compounds of . 
 
 
 . 176 
 
 Barometers . 
 
 
 . ' 10 
 
 air . 
 
 
 . 12 
 
 " Aneroid's . 
 
 
 . 12 
 
 *' corrections for 
 
 
 . II 
 
 " mercury . 
 
 
 . II 
 
 " variations of 
 
 
 . 12 
 
 Basic molecules 
 
 
 . 105 
 
 Batteries 
 
 
 • 71 
 
 " kinds of . . 
 
 
 • 71 
 
 " local action in 
 
 
 ■ 72 
 
 " polarization of 
 
 
 . 72 
 
 Beer .... 
 
 
 . 263 
 
 Benzine .... 
 
 
 . 265 
 
 " derivatives 
 
 
 . 267 
 
 " ring . 
 
 
 .265 
 
 Benzyl alcohol 
 
 
 
 271 
 
 Benzyl aldehide 273 
 
 *' compounds . , , .171 
 Benzoic acid 273 
 
 " derivatives . . . .272 
 
 Benzol . 366 
 
 Bilirubin 283 
 
 Biliverdin 283 
 
 Biniary molecules . . . .103 
 
 Bismuth 205 
 
 " compounds of . . . 205 
 
 *' oxides of .... 305 
 
 Bleaching powder . . . .142 
 
 Boiling 23 
 
 " point 33 
 
 Borax 163 
 
 Boric oxide 163 
 
 " or boracic acid . . . .162 
 Boron 161 
 
 " compounds of ... . i6a 
 Boyle's law of gases . . .12 
 
 Bromine. . . ... 146 
 
 " acids of 147 
 
 *' oxides of .... 147 
 
 Bromoform 215 
 
 Brucine 380 
 
 Bunsen's battery 73 
 
 Butane 250 
 
 Butter .... . , 256 
 
 Butyl alcohol 250 
 
 Butyric acid 351 
 
 C 
 
 Cadmium 183 
 
 Calcium 177 
 
 ** compounds of . . . .177 
 
 Calomel 187 
 
 Calorimetry 28 
 
 Camera-obscura 49 
 
 Capillary attraction .... 5 
 
 Camphor 377 
 
 Caoutchouc 378 
 
 Carbamide 220 
 
 Carbimide 226 
 
 Carbohydrates 258 
 
 Carbolic acid 367 
 
 Carbon 130 
 
 " dioxide .... 134* =21 
 
 '^ bi-sulphide . . . x53f2S3 
 '* monoxide . . . ... 136 
 
 " oxysulphide . . . .223 
 
Index, 
 
 287 
 
 Carbon tetrachloride . . . .215 
 
 Carbonator 139 
 
 Carbonyl 220 
 
 " chloride 220 
 
 ^' sulphide 220 
 
 Caseine 282 
 
 Cast iron 197 
 
 Caustic potash 172 
 
 " soda 171 
 
 Cellulose 260 
 
 Cement 178 
 
 Centigrade thermometer ... 16 
 
 Ceribrine 284 
 
 Change of state . ... 20 
 
 Charcoal 131 
 
 Chemical effects of current electricity 80 
 " " "- electric discharge 71 
 
 " electric batteries . . - 71 
 " hygrometers . , . 24 
 
 " reactions .... 107 
 ** sources of heat . . .30 
 
 Chemistry 91 
 
 Chloral 236 
 
 " hydrate 236 
 
 Chloric acid 145 
 
 Chlorine X41 
 
 ^^ acids o{ 143 
 
 ** compounds of . . . 143 
 
 " oxides of 143 
 
 Chloroform 214 
 
 Chlorous acid 145 
 
 " oxide 145 
 
 Choke damp 135 
 
 Chondrine 283 
 
 Chromic acid 193 
 
 " " battery .... 73 
 
 *' oxides 193 
 
 Chromium 192 
 
 '^ acids of . . . • Z93 
 *^ compounds of . . . 192 
 
 " oxides of ... . 192 
 
 Cinnamic acid 275 
 
 ** aldehyde .... 275 
 
 Citrates 255 
 
 Citric acid 255 
 
 Coal 131 
 
 Cobalt 197 
 
 Cocaine 280 
 
 Codeine 279 
 
 Coefficient of expansion ... 19 
 Cohesion 5 
 
 Cold, sources of 31 
 
 Collagin 283 
 
 Collodion 261 
 
 Color of bodies 43 
 
 Colors, complementary . . .43 
 
 " mixed 43 
 
 " simple 43 
 
 Combustion 91 
 
 Communicator 85 
 
 Compensation pendulum . . .19 
 Complementary colors . . .43 
 
 Compound ethers 216 
 
 " microscopes , . .48 
 *' molecules .... 100 
 " radicals .... 103 
 
 '^ ureas 221 
 
 Concave lenses 42 
 
 " mirrors 37 
 
 Condensation of electricity. . . 66 
 Condensing hygrometers . . .24 
 
 Conducted heat 26 
 
 Conductors 61 
 
 Conine 279 
 
 Continuous spectra . . . .46 
 
 Convected heat 26 - 
 
 Conversion of thermometric de- 
 grees 16 
 
 Convex lenses . . . . 42 
 
 " mirrors 38 
 
 Copper 185 
 
 " compounds of ... 186 
 Corrections for barometers . . n 
 Corrosive sublimate . . . .187 
 
 Coulumb 69 
 
 Creatine 284 
 
 Creatinine 284 
 
 Critical angle 40 
 
 Crystals 21 
 
 Cumenes 274 
 
 Current electricity . . . .69 
 " '* effects of . .79 
 
 " '* direction of . .73 
 
 " " measurement of . 75 
 
 " selector 76 
 
 Currents, thermo-electric . . .88 
 
 Curved mirrors 37 
 
 Cyanamides 225 
 
 Cyanates 227 
 
 Cyanic acid 228 
 
 Cyanides 227 
 
 Cyanogen 136 
 
288 
 
 Index. 
 
 Cynnal alcohol 275 
 
 Cymenes 274 
 
 Daguerre 50 
 
 Daguerreotypes , • . . . 50 
 
 Daniell's battery 72 
 
 Dark lines in spectrum . . -44 
 Declination of magnetic needle . 60 
 
 Degarager, Otto . . . .10 
 
 Delicate thermometers . . . 18 
 Deviation, angle of . . . .40 
 
 Developer 51 
 
 Dew-point 34 
 
 Dextrine 
 
 Dextrose .... 
 Diamond .... 
 Diastase .... 
 
 Diathermanic bodies . 
 Diazo-benzine nitrate . 
 Diffraction 
 Diffusion of gases 
 Digestor, Papin's . 
 Direction of electric currents 
 
 Dimethylamene 227 
 
 Discontinuous spectra . . .46 
 Dispension of light . . . -43 
 Dissipation of statical electricity . 62 
 
 Distillation 23 
 
 Distribution of statical electricity . 62 
 Double refraction . . . .53 
 
 Ductility 4 
 
 Dynamical electricity , . . .69 
 Dynamics, electro . . . .81 
 Dynamite 
 Dynamos 
 
 26a 
 
 258 
 
 130 
 
 263 
 
 26 
 
 269 
 
 53 
 
 32 
 
 23 
 
 75 
 
 84 
 
 Echo 
 Elastacine 
 Elasticity 
 Electro-dynamics 
 
 " motor force 
 Electricity 
 
 " attractions and repulsions 
 
 of . 
 
 " current 
 
 " dynamical 
 
 ** fricttonal 
 
 '* Intensity of 
 
 14 
 
 283 
 
 77 
 61 
 
 61 
 69 
 69 
 62 
 77 
 
 Electricity, kinds of . 
 ** resistance of 
 
 " statical 
 
 ** theories of 
 
 *' units of 
 
 Electrodes 
 Elements 
 
 Elemental molecules . 
 Emission theory of heat 
 " " " light 
 
 Empirical formula 
 Emulsion 
 Engines, work of . 
 Epsom salts 
 Equivalence . 
 Eserene . 
 Essential oils 
 Esters . 
 Ethane . 
 Ether 
 Ethers . 
 
 ** compound 
 " haloid 
 " sulphuric . 
 Ethyl acids and ethers 
 " alcohol 
 " aldehydes . 
 
 amides 
 '* amines 
 " chlorides 
 " oxalic acid . 
 " phosphines , 
 *' sulphides . 
 *' sulphuric acid 
 " urea 
 Ethylene 
 
 " glycol 
 Evaporation . 
 Expansion^ coefficient of 
 " of gases 
 
 " " liquids 
 
 *' " solids 
 
 Extraordinary images , 
 *' ray 
 
 " refraction 
 
 Eye-piece 
 
 Fahrenheit thermometers 
 Faradic currents . 
 
 16 
 83 
 
Index. 
 
 289 
 
 Faradic battery 86 
 
 Fats 256 
 
 Fatty group an 
 
 Fermentation 262 
 
 Ferments 262 
 
 Ferric cyanide 227 
 
 Ferri-ferro " 228 
 
 Ferrous " 227 
 
 Fibrine 283 
 
 Fibrinogen 2S2 
 
 Field lens 48 
 
 Fire-damp 133 
 
 Fluorescence 46 
 
 Fluorine 149 
 
 Foci of lenses 41 
 
 " " mirrors 37 
 
 Focus conjugate 37 
 
 ** principal 37 
 
 ** real 42 
 
 " virtual 42 
 
 Foot-pounds 31 
 
 Force, electro-motor .... 77 
 
 Form 3 
 
 Formamide 225 
 
 Formates 219 
 
 Formic acid zzS 
 
 Formula 100 
 
 Fowler solution 201 
 
 Franklin's theory of electricity . . 61 
 Fraunhofer's lines . . , '44 
 Frictional electricity . . . .6a 
 Fuming nitric acid .... 128 
 " sulphuric acid . . .157 
 
 Fusel oil 253 
 
 Fusion zo 
 
 G 
 
 Galactose 259 
 
 Galileo's telescope . . . .49 
 
 Gallic acid 273 
 
 Galvani's experiment . . . .69 
 
 Galvanometer 75 
 
 Galvano-plastics 80 
 
 Gaseous state 5 
 
 Gases 10 
 
 " expansion of , . , .19 
 
 '* law of 12 
 
 " specific gravity of . . .13 
 
 Glass 161 
 
 Glucose 25^ 
 
 Glucosides 261 
 
 Glyceric acid 245 
 
 Glycerine 24S 
 
 Glycerol ... . . 284 
 
 Glycogen 260 
 
 Glycollates 238 
 
 GlycoUide 238 
 
 Glycol nitric esters .... 248 
 Glycols ... . . 237 
 
 Gold 189 
 
 " compounds of ... . igo 
 
 Graphic symbol 99 
 
 Graphite 131 
 
 Gravitation 5 
 
 " laws of , , . . 5 
 
 Gravity 6 
 
 " battery 74 
 
 Green fire 177 
 
 Grenet battery 73 
 
 Ground air 124 
 
 Grove's battery 73 
 
 Gun-cotton 261 
 
 Gunpowder 172 
 
 Gutta-percha 278 
 
 Gypsum . . .... 178 
 
 H 
 
 Halogens 141 
 
 Haloid ethers .... 214 
 
 Hardness 4 
 
 Heat .15 
 
 " conducted 26 
 
 " convected 26 
 
 " latent 20 
 
 ** mechanical equivalent of . ■ 32 
 " quantities of .... 28 
 
 " radiated 26 
 
 " reflection of .... 27 
 
 " specific 28 
 
 " sources of ... . 30 
 
 " theories of 15 
 
 " transmission of . , . .26 
 
 Heating effects of electric discharge . 67 
 
 ** *' "■ current electricity, 79 
 
 Hemaglobine 285 
 
 Hexane compounds .... 254 
 
 Hexyl alcohol 254 
 
 Hippuric acid ... . 274 
 
 Holtz machine 65 
 
 Homogeneous light .... 44 
 
290 
 
 Index, 
 
 Homogeneous medium 
 
 Homologous series 
 
 Horse-power 
 
 Hydraulic press . 
 
 Hydriodicacid 
 
 Hydrocarbons 
 
 Hydrocyanic acid 
 
 Hydrogen 
 
 ** antimonide 
 
 " arsenide 
 
 " bromide 
 
 *' carbide 
 " chloride 
 ** cyanide 
 *' dicarbide 
 
 " nitride . 
 
 " ' oxide . 
 " peroxide 
 
 " phosphide 
 " silicide 
 
 " sulphide 
 
 Hydrobromic acid 
 
 Hydrochloric " . 
 
 ** " type 
 
 Hydrofluoric " . 
 
 Hydrometers , 
 
 Hygrometers . 
 
 *' absorbing 
 '* chemical 
 "■ condensing 
 " wet bulb 
 
 Hygrometry . 
 
 Hyponitrous acid 
 " oxide 
 
 Hypophosphites . 
 
 • 34 
 . 210 
 
 . 32 
 
 . 8 
 
 . 149 
 
 . 21Z 
 137, 226 
 
 . Ill 
 
 . 203 
 
 ■ 199 
 
 • 147 
 
 ■ 133 
 
 ■ 144 
 
 • 137 
 
 • 133 
 . 125 
 
 • "S 
 . 120 
 
 . x&S 
 
 ■ 159 
 . 152 
 . 147 
 
 • 144 
 . 101 
 . 150 
 . 3 
 . 24 
 . 25 
 . 24 
 . 24 
 . 24 
 . 24 
 . 126 
 . 126 
 . 169 
 
 Index of refraction . . . .39 
 
 India-rubber 278 
 
 Indican 279 
 
 Indigo blue 279 
 
 " white 279 
 
 Induction apparatus . . . .84 
 
 ** coils 85 
 
 *' magnetic ... .60 
 
 " statical 62 
 
 " voltaic 83 
 
 Inertia 3 
 
 Inorganic chemistry . . . ,109 
 
 Intensity of light 35 
 
 " '* " laws of 
 
 '* *' sound 
 
 Interference of light 
 
 " *' polarized light 
 
 Insulators .... 
 Iodic acid .... 
 
 lodiform 215 
 
 Iodine 148 
 
 " acids of 149 
 
 " oxides of 149 
 
 Iron 196 
 
 " compounds of . . . 197, 227 
 " oxides of .... 197 
 
 Isatin 279 
 
 Isolutyl alcohol 250 
 
 Isomeric compounds .... 210 
 
 K 
 
 Kathode 76 
 
 Ketone 246 
 
 35 
 14 
 53 
 54 
 61 
 149 
 
 Illuminating gas . 
 Image, extraordinary 
 
 " ordinary . 
 
 *' multiple 
 
 " real . 
 
 " virtual 
 Imides . 
 Imodogen 
 Impenetrability . 
 Incandescent light 
 Inclination of needle 
 lucident angle of refraction 
 " " '* reflection 
 
 Lactamide 
 
 Lactates , 
 
 138 Lactic acid 
 
 53 " esters . 
 
 53 Lactose . 
 
 37 Lamps, electric 
 
 37 Latent heat . 
 
 37 *' *' of steam 
 
 226 " '* " vapors 
 
 224 '* " '* water 
 
 3 Law, Archimedes' 
 
 79 " Avogadro*s . 
 
 60 ** Boyle's . 
 
 36 ** Pascal's 
 
 30 '* of electrical attractions 
 
 247 
 
 ■ Z47 
 . 247 
 - 247 
 259 
 • 79 
 
Index, 
 
 291 
 
 Law of electrical repulsions 
 
 " " electro -motor, force 
 
 " " gases 
 
 " " gravitation 
 
 " " intensity of light . 
 
 " '* magnetic attractions 
 
 " *' ''' repulsioqs 
 
 " ** reflection of light 
 Lead 
 
 " compounds of 
 Le Blanc's soda process 
 Leclanche battery . 
 Lenthine . 
 Lenses 
 
 achromatic . 
 concave 
 convex 
 foci of . 
 
 principal foci of 
 Leucine . 
 
 Levers .... 
 Levulose 
 Leyden jar . 
 Light . . . 
 
 " depression of 
 
 " homogeneous 
 
 " intensity of . 
 
 " interference of 
 
 " pencil of 
 
 ** polarization of 
 
 " ray of . 
 
 •• reflection of , 
 
 " refraction of . 
 
 " sources of 
 
 " theories of . 
 
 ■"^ transmission of 
 
 " velocity of . 
 Lightning rods 
 Lime . ... 
 Liquid state . 
 Liquids . 
 
 " expansion of 
 
 ** rotatory power of 
 
 " specific gravity of 
 
 Liquefaction of vapors 
 
 Litharge .... 
 
 Litliium .... 
 
 *' compounds of . 
 
 Local action in batteries 
 
 Luminous effect of current electricity, 
 
 " " ** electric, discharge , 
 
 61 
 
 77 
 12 
 
 5 
 33 
 59 
 59 
 36 
 184 
 x8s 
 171 
 
 74 
 283 
 41 
 47 
 42 
 42 
 41 
 42 
 283 
 
 7 
 
 259 
 
 66 
 
 33 
 
 43 
 
 44 
 
 35 
 
 53 
 
 34 
 
 54 
 
 34 
 
 36 
 
 36 
 
 57 
 
 33 
 
 41 
 
 34 
 
 68 
 
 177 
 
 5 
 
 8 
 
 19 
 
 58 
 
 3 
 
 23 
 
 185 
 
 173 
 
 174 
 
 72 
 
 79 
 
 67 
 
 M 
 
 Machines, magneto-electric 
 " simple . 
 '* statical electric 
 Magic-lantern 
 Magnesia 
 Magnesium . 
 
 " compounds of 
 
 Magnet .... 
 
 *^ artificial 
 
 natural 
 
 " permanent . 
 
 " properties of 
 
 '* temporarj- . 
 
 Magnetic attraction and repulsion 
 
 " effects of current electricity, 
 
 " '* ** electric discharge 
 
 " induction 
 
 " poles 
 
 " rupture . 
 
 Magnetism 
 
 *' residual 
 " theories of 
 Magneto-electric machines . 
 Magnets, inclination of 
 ** declination of 
 •^^ neutral point of 
 Malleability .... 
 Malic acid .... 
 Malonic acid .... 
 Manganese .... 
 ** acids of 
 ** compounds of . 
 " oxides of 
 
 Mannite 
 
 Marsh gas .... 
 " type 
 
 Masses 
 
 ^' forces governing . 
 
 Matter 
 
 " divisibility of . 
 *'' divisions pf 
 " forces governing 
 " properties of 
 Measurement of current electricity 
 Mechanical sources of heat 
 
 " efi^ects of electric 
 
 charge .... 
 Mechanical equivalent of heat 
 Melanine .... 
 
 dis- 
 
292 
 
 Index, 
 
 Metals 170 
 
 Methane 213 
 
 Methyl, alcohol 217 
 
 " aldehyde .... 218 
 
 ** amine 225 
 
 " arsenic 230 
 
 " benzine 271 
 
 " bromide 214 
 
 " chloride . ... 214 
 
 " ether 218 
 
 " iodide 214 
 
 " nitric acid .... 217 
 " phosphines .... 229 
 " phosphoric acid . . . 218 
 " sulphaldehide . . . 222 
 ** sulphates .... 218 
 " sulphides .... 222 
 " sulphonic acid . . . 223 
 *' sulphuric " . . 217 
 
 "■ urea 221 
 
 Mercury 187 
 
 " barometers ... 11 
 
 " compounds of . . . 187 
 
 " thermometers . . .16 
 
 Meta-phosphoric acid . . . . i63 
 
 *■■ phosphates 168 
 
 *' silicic acid 160 
 
 Methane 133 
 
 Microscope 48 
 
 ** compound . . .48 
 
 " simple .... 48 
 
 Mineral waters 1x5 
 
 Mirage 4° 
 
 Mirrors 36 
 
 '* concave 37 
 
 " convex 38 
 
 " curved 37 
 
 " parabolic . . . .38 
 
 " plane 36 
 
 *' spheroidal , . . .37 
 
 Misoxal acid 245 
 
 Mixed colors 43 
 
 Molecular weight 97 
 
 Molecules 4 
 
 '* forces governing . . s 
 
 Morphine 279 
 
 Mortar 178 
 
 Mosaic gold 181 
 
 Mucosine 283 
 
 Multiple images 37 
 
 Multiplication of atoms • ■ • 99 
 
 Mustard oil 249 
 
 Myosine 283 
 
 N 
 
 Naphthaline 276 
 
 Naphthol 277 
 
 Narcotine 279 
 
 Natural magnets 69 
 
 Negative atoms gg 
 
 " pictures . . . .51 
 
 " plates of battery . . .71 
 
 *' poles " ... 71 
 
 Neutral point of magnets . . . sg 
 
 Newton's rings 54 
 
 Nickel 198 
 
 Nicol's prism 55 
 
 Nicotine 27g 
 
 Nitre 172 
 
 Nitrils 226 
 
 Nitro-benzine 267 
 
 " glycerine 248 
 
 Nitric acid 127 
 
 Nitrogen 122 
 
 " acids of 126 
 
 " oxides of .... 126 
 
 " dioxide ia8 
 
 '* teroxide 127 
 
 Nitrous acid X27 
 
 Non-conductors 6z 
 
 O 
 
 Object glass 48 
 
 Objective 48 
 
 Oils 256 
 
 Olefiant gas 133 
 
 '* series 211 
 
 Oleic acid 256 
 
 Olein 256 
 
 Opaque bodies 33 
 
 Opera glass 4g 
 
 Optical instruments , . , .48 
 
 Ordinary image 53 
 
 ray 53 
 
 *' refraction . . , .54 
 
 Ortho-phosphates . , . .167 
 
 "■ phosphoric acid , , , .167 
 
 Oxalates . , . . . .238 
 
 Oxalic acid . . . . . .238 
 
 *' ether 238 
 
Index. 
 
 293 
 
 Oxamide 241 
 
 Oxygen 113 
 
 Ozone ...,,,, 120 
 
 P 
 
 Palmitic acid 256 
 
 Palmitin 256 
 
 Pancreatin 283 
 
 Papia's digestor 23 
 
 Parabolic mirrors . . . .38 
 
 Paraffins 211 
 
 Paraglobulin 282 
 
 Paris green 201 
 
 Pascal's experiment . , . .10 
 
 Pascal's law 8 
 
 Pencil of light 84 
 
 Pendulum, compensating . . .19 
 
 Pentane 253 
 
 Penumbra 34 
 
 Pepsin 283 
 
 Peptone 283 
 
 Perchloric acid 146 
 
 Perisad g8 
 
 " radicals 104 
 
 Phenates 268 
 
 Phenol 267 
 
 " allyl alcohol . . . .275 
 
 Phosphorescence 57 
 
 Phosphorus 164 
 
 " acids of . . . .166 
 
 " oxides of ... 165 
 
 Phosphoric oxide 166 
 
 Phosphine 165 
 
 Phosphines 229 
 
 Phosphinic acid 229 
 
 '^ ethers . . , .228 
 
 Photography 50 
 
 Photometers 35 
 
 Physics 3 
 
 Physical sources of heat ... 30 
 Physiological effects of electric dis- 
 charge 67 
 
 Physiological effects of electric cur- 
 rent 80 
 
 Picrates 268 
 
 Picric acid ...... 268 
 
 Pictures, negative .... 51 
 
 ^^ positive 51 
 
 Pig-iron 197 
 
 Pile, thermo-electric • . • .88 
 
 Pile, voltaic 69 
 
 Pitch 14 
 
 Plane mirrors 36 
 
 Plate, electric machines . . . 65 
 
 Plaster of Paris 178 
 
 Platinum 189 
 
 " compounds of . . . 189 
 
 Polarity , g 
 
 Polarization of light , . . .54 
 
 '* *' '* means of . .55 
 
 ** " negative plate . . 72 
 
 Polarized light, interference of . .56 
 
 Polarizer 55 
 
 Poles of magnet 59 
 
 " " battery 71 
 
 Positive atoms 99 
 
 " metal 71 
 
 " pictures 51 
 
 ** pole 71 
 
 Potassium 172 
 
 " compounds of . . . 172 
 
 " cyanide .... 227 
 
 " ferri-cyanide . , . 226 
 
 " ferro '* , . . , 227 
 
 Potential 61 
 
 Power 7 
 
 Principal axis of mirror , , .37 
 " foci ** " ... 37 
 
 ** foci of lenses . . .42 
 
 Prisms 41 
 
 " Nicol's ss 
 
 Propane 242 
 
 Propeine 242 
 
 Properties of magnets . . , .59 
 " " spectrum , . ,44 
 
 " ** statical electricity , . 62 
 
 Propine 242 
 
 Propronic acid 246 
 
 Propyl alcohol 246 
 
 " glycol 246 
 
 " iodide 242 
 
 Propylene 242 
 
 *' iodide 243 
 
 Prussicacid 226 
 
 Psychrometers 23 
 
 Pumps, air .is 
 
 " Sprengel's air . . , .13 
 
 Pyrogallic acid 26S 
 
 Pyrophosphates 168 
 
 Pyro phosphoric acid .... 167 
 Pyrometers 18 
 
294 
 
 Index. 
 
 Quality of sound 14 
 
 Quantities of heat , . . .28 
 Quinine 380 
 
 R 
 
 Radiated heat 
 Radicals 
 
 Rational formula . 
 Ray extraordinary 
 " of light . 
 " ordinary 
 Real images . 
 
 " foci of lenses 
 Red fire .... 
 Reaumur's thermometer 
 Reflected heat 
 Reflecting surfaces 
 Reflection^ a-ngle of 
 of light 
 
 '* '' " laws of 
 
 Refraction, angle of . 
 
 *' index of . 
 
 ** double 
 
 *^ extraordinary 
 
 " of light . 
 
 *' ordinary . 
 
 " total . 
 
 Repulsion 
 
 Residual magnetism . 
 Resins 
 
 Rheophores- . 
 Rheostat 
 
 Rotatory power of liquids 
 Rupture of magnets . 
 Rhumkorff's coil . 
 
 the 
 
 Saccharimeter, Soleil*s 
 
 Saccharose 
 
 Saleratus 
 
 Salicylates . . . . 
 
 Salicylic acid 
 
 Salt. 
 
 Saltpetre 
 
 Salts . . 
 
 Saturated compounds 
 ** molecules 
 *' vapors, . 
 
 103 
 
 100 
 
 53 
 
 34 
 
 53 
 
 37 
 
 41 
 
 176 
 
 16 
 
 27 
 
 , 36 
 
 ■ 36 
 
 • 39 
 . 36 
 
 ■ 39 
 
 • .39 
 
 ■ S3 
 . 53 
 
 ■ 39 
 
 • S3 
 
 ■ 40 
 
 ■ S 
 . 8z 
 
 • 277 
 . 76 
 . 76 
 . S6 
 . 60 
 , 8s 
 
 ■ S6 
 
 . 256 
 
 173 
 
 , S73 
 
 =73 
 
 171 
 
 , 171 
 
 . loS 
 
 , 2og 
 
 , 103 
 
 Secondary axis . . . . 
 
 • 37 
 
 Sesqui 
 
 . 102 
 
 Shadows 
 
 ■ 34 
 
 Scheele's green . . . . 
 
 . 201 
 
 Silica 
 
 . 160 
 
 Silicon 
 
 . 160 
 
 " acids „ . 
 
 . 160 
 
 " compounds of . 
 
 . 160 
 
 '' oxides 
 
 . 160 
 
 Silver 
 
 . 190 
 
 '* compo.unds of . . . 
 
 . 191 
 
 Simple colors . . . . 
 
 • 43 
 
 " electric battery 
 
 ■ 72 
 
 " microscope- 
 
 . 48 
 
 " radicals 
 
 ■ 103 
 
 Soaps 
 
 • 2S7 
 
 Soda 
 
 . 171 
 
 Sodium 
 
 . 170 
 
 " compounds of . 
 
 ■ 171 
 
 Solar spectrum ... 
 
 • 43 
 
 Soleil's saccharimeter . 
 
 . 56 
 
 Solid state .... 
 
 • 4 
 
 Solids ... 
 
 . 4 
 
 ^' expansion of 
 
 . 8 
 
 " specific gravity of 
 
 ■ 19 
 
 Sound 
 
 • 14 
 
 Sources of cold 
 
 • 31 
 
 " heat . 
 
 • 30 
 
 "light . 
 
 ■ S7 
 
 Specific gravity . 
 
 . 6 
 
 " bottle . . 
 
 . 8 
 
 " " means of obtainir 
 
 ig . 8 
 
 *' " of gases 
 
 . 13 
 
 " " " liquids . . 
 
 . 8 
 
 solids . 
 
 . 8 
 
 " heat. .... 
 
 . 28 
 
 Spectra, absorption 
 
 . 46 
 
 band 
 
 . 46 
 
 •' continuous 
 
 . 46 
 
 " discontinuous 
 
 . 46 
 
 " kinds of . 
 
 . 46 
 
 Spectroscope .... 
 
 • 4S 
 
 Spectrum analysis 
 
 ■ 45 
 
 " dark lines in 
 
 ■ 44 
 
 " properties of 
 
 • 44 
 
 " solar . 
 
 ■ 43 
 
 Spermaceti .... 
 
 . 257 
 
 Spherical aberration of lenses 
 
 • 42 
 
 " " " mirrors 
 
 . 38 
 
 Spheroidal condition . 
 
 • 23 
 
 " mirrors 
 
 • 37 
 
Index. 
 
 295 
 
 Sprengel's air pump 
 
 Stannic acid . 
 " chloride . 
 " oxide 
 
 Stannous acid 
 
 " chloride . 
 " oxide 
 
 Starch . 
 
 State, hygrometric 
 ^' spheroidal . 
 
 Statical electricity 
 
 " " distribution of 
 
 '* " dissipation of 
 
 " " induction by 
 
 " ** properties of 
 
 " electric machines . 
 
 Stearic acid 
 
 Stearin . 
 
 Steel 
 
 Strontium 
 
 " compounds of 
 
 Strychnine 
 
 Succinic acid . 
 
 Sugar cane 
 " grape . 
 " milk 
 
 Sulphocyanates . 
 
 Sulphocyanic acid 
 
 Sulpho-sulphuric acid 
 
 Sulphur . 
 
 Sulphuretted hydrogen 
 
 Sulphuric acid 
 
 " oxide . 
 
 Sulphurous acid . 
 " oxide . 
 
 Synthesis 
 
 Syntonine 
 
 Tannic acid . 
 
 Tartar .... 
 
 "^ emetic. 
 Tartrates 
 Tartaric acid . 
 Tartronic acid 
 Taurocholates 
 Telephone 
 Telescopes, astronomical 
 
 " Galileo's . 
 
 " terrestrial . 
 
 13 
 180 
 180 
 180 
 
 . 180 
 180 
 
 . 180 
 
 259 
 24 
 
 23 
 62 
 , 62 
 . 6z 
 , 62 
 . 62 
 64 
 
 , 256 
 . 256 
 . 180 
 . 176 
 . 176 
 . 280 
 
 ■ 251 
 
 ■ 259 
 . 258 
 
 • 259 
 . 2^ 
 . 228 
 
 ■ 157 
 
 ■ iSi 
 
 - 152 
 
 • 155 
 
 ■ 155 
 
 • 154 
 
 • 154 
 
 • 91 
 
 . 285 
 
 273 
 
 . 252 
 
 205 
 
 , 252 
 
 . 252 
 
 Z4S 
 
 284 
 
 36 
 
 48 
 
 49 
 
 49 
 
 Temperature . 
 
 Temporary magnets 
 
 Tenacity 
 
 Tension of vapors 
 
 Ternary molecules 
 
 Terrestrial telescope . 
 
 Tests for arsenic . 
 
 Theonic acids 
 
 Theoretical chemistry . 
 
 Theories of electricity . 
 " '* heat . 
 " light . 
 " '* magnetism 
 
 Thermal unit . 
 
 Thermometers 
 
 '* accurate 
 
 '* air . 
 
 *' alcohol . 
 
 " Centigrade 
 
 " delicate 
 
 " Fahrenheit 
 
 '^ mercury 
 
 *^ Reaumur 
 
 Thermo-electric currents 
 " " pile 
 
 Thermometric corrections 
 
 Thio-sulphuric acid 
 
 Tin 
 
 " acids of . 
 " oxides of. 
 
 Tolum . 
 
 Torricelli's experiment 
 *' vacuum 
 
 Total inflection 
 
 Translucent bodies 
 
 Transparent bodies 
 
 Transmission of light 
 
 Trimethylamlne . 
 
 Trypsine 
 
 Turpentine . 
 
 Turpeth mineral . 
 
 Type formula 
 
 U 
 
 Undulatory theory of heat . . .15 
 " " " light ... 33 
 
 Unit, thermal ... .28 
 
 Unsaturated compounds . 209 
 
 '* molecules . 109 
 
 Urates , 254 
 
 15 
 
 58 
 
 4 
 
 49 
 202 
 
 157 
 
 , 91 
 
 61 
 
 ■ IS 
 • 33 
 . 58 
 . 28 
 
 ■ 15 
 . 18 
 
 ■ >7 
 
 ■ 17 
 16 
 18 
 
 . i5 
 . 16 
 . 16 
 
 16 
 
 157 
 
 179 
 
 180 
 
 180 
 
 271 
 
 10 
 
 II 
 
 , 46 
 
 ' 33 
 
 ' 33 
 
 ' 41 
 
 . 225 
 
296 
 
 Index, 
 
 Urea 
 
 "■ nitrate of 
 Uric acid 
 Urocrome 
 
 Vacuum 
 
 Valerianates . 
 
 Valerianic acid 
 
 Vaporization . 
 
 Vapors . 
 
 " latent heat of 
 " liquefaction of 
 *' saturated . 
 " tension of 
 
 Vegetable economy 
 " heat 
 
 Vegetation, process of 
 
 Velocity of discharge 
 "light . 
 " " sound . 
 
 Verdigris 
 
 Vinegar 
 
 Visual force of lenses 
 " images 
 
 Volt . . * . 
 
 Voltaic arc 
 
 220 
 
 , 221 
 254 
 
 2S4 
 
 253 
 
 140 
 
 30 
 
 31 
 
 34 
 
 31 
 
 , 14 
 
 237 
 
 237 
 
 42 
 
 37 
 
 , 70 
 
 ■ 79 
 
 Voltaic induction . 
 
 '' pile 
 Vulcanite 
 
 W 
 
 Water . 
 
 " latent heat of 
 
 " type . 
 Watt 
 
 Wet-bulb hygrometers 
 Whiskey 
 
 White precipitate . 
 Wines 
 
 Wood spirits . 
 Work of engines . 
 Wrought iron 
 
 X 
 
 Xylenes 
 
 Veast plant 
 
 Zinc 
 
 83 
 
 6q 
 
 , 278 
 
 70 
 
 25 
 
 . 264 
 . 188 
 , 263 
 , 217 
 ■ 32 
 , 197 
 
 compounds of 
 
 THE END.