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 https://archive.org/details/introductiontogeOOhinr 
 
Ricordiamoci in grazia, che il cercar 
 la costituzione del mondo e dc’ maggiori 
 e de’ pin nobili problcmi, che sieno in 
 natura. 
 
 Galileo Galilei. 
 
 Gj. II., Sistemi. 
 
LAVOISIER. 
 
 EXPERIMENTUM CRUCIS. 
 
INTRODUCTION 
 
 TO 
 
 GENERAL CHEMISTRY. 
 
 A GRADED COURSE OF 
 
 ONE HUNDRED LECTURES 
 
 BY 
 
 GUSTAVUS DETLEF HINRICHS, M.D., LL.D. 
 
 HONORARY AND CORRESPONDING MEMBER OF SCIENTIFIC SOCIETIES IN FRANCE, 
 GERMANY AND THE UNITED STATES) PROFESSOR OF CHEMISTRY, 
 
 ST. LOUIS COLLEGE OF PHARMACY. 
 
 WITH AX 
 
 ATLAS OF EIGHTY 
 
 PLATES, 
 
 REPRESENTING CHEMISTS, INSTITUTIONS, PRIME MATERIALS, 
 CRYSTALS, DIAGRAMS AND APPARATUS) AND ILLUSTRATIONS IN THE TEXT. 
 
 ST. LOUIS, MO., U. S. 
 
 CARL GUSTAV HINRICHS, PUBLISHER. 
 
 NEW YORK AND LEIPZIG, LEMCKE AND BUECHNER. 
 London, H. Grevel & Co. Paris, H. Le Soudier. 
 
 1897. 
 
Entered According to Act of Congress, in the year 1897. by 
 Gustavus Hinrichs, 
 
 In the Office of the Librarian of Congress, at Washington. 
 
 ALL RIGHTS RESERVED BY THE AETHOR. 
 
 PHOTO-ENGRAVINGS BY SANDERS ENGRAVING CO., 
 ST. LOUIS, MO. 
 
 PRINTED BY R. P. STUDLEY & CO., 
 ST. LOUIS, MO. 
 
S'vt> p , , V 
 
 TO 
 
 Charles Friedel, 
 
 MEMBER OF THE INSTITUTE OF FRANCE, 
 
 PROFESSOR OF THE FACULTY OF SCIENCES. 
 
 CONSERVATOR OF THE M I N ER A LOGI C A L MUSEUM 
 OF THE NATIONAL SCHOOL OF MINES. OF PARIS. 
 
 THIS VOLUME 
 
 IS DEDICATED BY 
 
 The Author 
 
MONSIEUR CHARLES FRIEDEL, 
 
 MEMBRE DE L’ INSTITUT, 
 
 Paris, France. 
 
 My Dear Sir : 
 
 The Introduction to General Chemistry here- 
 with most respectfully dedicated to you, is intended 
 to give the student a first view of the broad field of 
 science that has been enriched by your researches, 
 and to serve as a supplement to existing treatises 
 of our science. 
 
 To you, the form of a crystal, the synthesis of 
 a mineral and the formation of a new series of 
 organic compounds have been chemical problems 
 of equal importance. Hence the solution of every 
 single problem by your hands has enriched chem- 
 istry with a new principle as broad as the horizon 
 of your mind. 
 
 Thus, when you made the ancient dwarfs 
 of the mountain speak, the crystal revealed to you 
 its true composition. Upon this you built an 
 organic chemistry of the deep, of which that of 
 air and sun is like the spirit. 
 
Your official trusts have been as broad as your 
 
 chemical work. The magnificent collection of 
 / 
 
 minerals at the Ecole des Mines, and Organic 
 Chemistry at the Sorbonne, have been equally 
 benefitted by that breadth of mind which the 
 specialist cannot even understand. 
 
 I 
 
 Your recent establishment of Les Actualites 
 Chimiques makes all chemists of the world your 
 debtors. The Great Chemist of the North 
 first sacrificed his time to such a task, eighty years 
 ago. For a while, his creation was continued in 
 another country, by the kindred minds of a Liebig 
 and a Woehler. But with modern Byzantinism, the 
 Jahresberichte have depreciated in character even 
 more than they have increased in bulk. You 
 happily have found a form in which the thought of 
 Berzelius arises to new life for the good of science. 
 
 That your Colleague, Professor Schuetzen- 
 berger of the College de France, under your presi- 
 dency, has delivered a Lecture on work of mine to 
 the chemists of Paris, at the Sorbonne, and that you 
 have opened your new Review with a full report 
 thereof, is acknowledged as a great distinction 
 with gratitude by 
 
 THF AUTHOR. 
 
 St. Louis, Mo., U. S., March 15, 1897. 
 

 A 
 
 ^^'Z^'^-r — e^c^ 
 
Je me suis propose d’embrasser, dans ma publication, la 
 science tout entiere; mon livre sera complet, quand au but; 
 il ne sera elementaire que par le choix des methodes. 
 
 FRANCOIS ARAGO, 
 
 Astr.-pop. T. I., 1854, 
 
PREFACE. 
 
 This work embodies the experience of nearly forty years 
 behind the Lecture Table. I have addressed fully ten thousand 
 students in the aggregate. 
 
 For a century, our chemical text- books have been modelled 
 on one pattern. They all begin with general principles that 
 require advanced knowledge to be understood. The student 
 is first directed to observe that which he cannot see, and to 
 comprehend that which it took old chemists centuries to learn. 
 At the same time, that which is common and of great practical 
 importance, is withheld till late in the course or entirely 
 omitted. Many gases that were of special interest a century 
 ago, are still made prominent, though of no significance at 
 present, while the instructive and useful gasometric processes 
 are given no place. 
 
 A reformation seems necessary. It has been attempted 
 in this book. The entire science is presented in a strictly 
 graded course. The principal points are determined in the 
 order of their historic growth. The discovery of oxygen is 
 not presented until its necessity can be understood ; it comes 
 as the dramatic event that it actually was in history. The 
 atomic theory comes last, and is here carried to completion. 
 
 The real authors of chemistry are the chemists that 
 created the science. Hence the portraits of the makers pre- 
 cede their work. The other parts of the Atlas are equally 
 essentfal. The pictorial representation of the prime materials 
 we would like to have increased largely. 
 
 11 
 
The present is the Lecture Course exclusively. It is 
 supplemented by a Laboratory Course, the guide for which it 
 is our intention to issue in another year. The lecture is not 
 the place for details on processes and apparatus. It is as 
 impossible to teach as it is to learn such details in the lecture 
 hall. At the laboratory stand such knowledge is acquired 
 almost without an effort. 
 
 The plates of apparatus are largely suggestive of what is 
 presented at each lecture. The experiments are sufficiently 
 indicated in the text. Neither apparatus, nor experiment, 
 should ever be introduced simply for show or amusement. 
 They are means to an end, namely the establishment of 
 chemical facts and principles. 
 
 This book does not aim to be a systematic treatise on 
 compounds. Of such books there are enough. The best by 
 far is the Traite of Troost, (11th edit., Paris, 1895); it is a 
 masterpiece of completeness and condensation ; it gives a 
 maximum of chemistry in a minimum of space. 
 
 The selection of topics, and their order of succession, has 
 been to me a matter of much study and consideration for many 
 years. The text has also been most carefully written and 
 re-written. It has been my constant aim to make the text 
 concise and clear. Each lecture deals with a single, definite 
 topic. It is treated as a subject by itself. The best French 
 writers have been my models of style. 
 
 But the work is before the reader and the student, 
 respectfully submit it to their consideration. 
 
 
 Si GCiESTiox: In a first course it is advisable to omit the more 
 difficult quantitative inorganic part (Lectures 38 to 51) till Lecture 80 in 
 organic chemistrv has been heard. After that, and perhaps a review, 
 the more difficult quantative parts can be taken with greatest advantage. 
 
CONTENTS. 
 
 TEXT OF ONE HUNDRED LECTURES. 
 
 INORGANIC CHEMISTRY 
 
 I. Chemic.vl Agencies: 
 
 I, Chemistry and A 1 Kemi. 2, Weight and Measure. 3, Solids 
 and Fluids. 4, Fusing and Boiling. 3, Furnace and Blowpipe. 
 
 II. Metals .\xi) Minerals: 
 
 6, Metals, old and new. 7, Calcination and Reduction. 8, Alloys 
 and Amalgams. 9, Ores and Cleavage. 10, Crystal Gems. 
 II, Crystal Stones. 12, Rocks and Veins. 13, Salts and Spirits. 
 14^ Solution and Crystallization. 15, Crystal Description. 
 
 III. Chemical Reactions : 
 
 16, Marble and Fixed Air. 17, Zinc and Inflammable Air. 18, 
 Substitution by Solution. 19^ Solution of Silver and Gold. 20^ Re- 
 duction in the Wet Way. 21^ Sulphur and Sulphides. 22, Hydrogen 
 Sulphide and the Metals. 23, Iodine and Iodides. 24^ Acidimetry 
 and Alkalimetry. 25, Neutralization and Caloration. 26, Flux and 
 Glass. 27, Metals and Radicals. 28, Chemical Reactions. 
 
 IV. Combustion: 
 
 29, Combustion and Phlogiston. 30^ Combustion and Oxygen. 
 31, Oxide and Radical. 32^ Analysis of the Air. 33^ Nitrogen, 
 Phosphorus and Argon. 
 
 V. Electrolysis : 
 
 34, Battery and Dynamo. 35, Qualitative Electrolysis. 36, 
 Applied Electrolysis. 37, Equivalent and Electricity. 
 
 VI. Chemical Formulae: 
 
 38, Equivalent and Volume. 39, Equivalent and Heat. 40, Atoms 
 and Molecules. 41, Elements and Compounds. 42, Allotropy and 
 Isomery. 43, Binaries and Ternaries. 44, Formula and Compound. 
 
 \TI. Chemical Analysis: 
 
 Quantitative: 45, Purity and Strength. 46, The Analytical 
 
 Balance. 47, Specific Gravity Methods. 48, Analysis by Dissocia- 
 tion. 49, Gasometric Analysis. 50, Volumetric Analvsis. 51, 
 Gravimetric Analysis. 
 
 Qualitative: 52, Spectrum Analysis. 53, Dry Way Analysis. 
 54, Wet Way Analysis of Bases. 55, W'et Way Analysis of Acids. 
 56, Recognition of Specimens. 
 
 13 
 
ORGANIC CHEMISTRY. 
 
 VIII. Organic Prime Materials: 
 
 \"egetable: 57, Organic Prime Materials. 58, Sugar and Wine. 
 59, Fats apd Oils. 60, Flower and Fragrance. 61, Indigo and 
 Madder. 62, Balsam and Resin. 63, Vegetable Acids. 64, Vege- 
 table Bases. 65, Neutral Principles. 66, Starch and briber. 
 
 Animal: 67, Milk and Butter. 68, Flesh and Blood. 69, Bone 
 and Sinew. 70, Animal and Plant. 71, Fermentation and Life. 
 
 Fossil: 72, Petroleum and Coal. 73, Gas and Tar. 74, Phenol 
 and Aniline. 75, Bone Oil and Wood Spirits. 
 
 IX. Chemical Transformations: 
 
 76, Starch, Sugar and Glucose. 77, Alcohol and Ethers. 78, Fats 
 and Soaps. 79, Nitro-Glycerin and Gun-Cotton. 80, Chloracetic 
 Acid and Chloral. 
 
 X. Chemical Constitution: 
 
 81, Proximate and Ultimate Analysis. 82, Empirical and Molecular 
 Formulae. 83, Radical and Structural Formulae. 84, Polymeric and 
 Isomeric Compounds. 85, Right- and Left-Handed Compounds. 
 86, Tetrahedron and Benzol Ring. 87, Alcoholic Compounds. 
 88, Aromatic Compounds. 89, Complex Compounds. 90, Organic 
 Synthesis. 
 
 XI. Atom-Mechanics : 
 
 91, The Atom World. 92, Prismatic Atoms and Boiling. 93, Atom 
 Linkage and Fusing. 94, Atom Volume. 95, Isomeric Atoms. 
 96, Atomic Rotation. 97, Atomic Libr2Ption. 98, Atomic Crystals. 
 99, Atomic Weights. 100, The Atomic Composition of the Elements. 
 
 ERRATA. 
 
 LECT. 24. Sect. 5: For 5 cc read 50 cc; for 7 in line 5 read 31; 
 Sect. 12, line i, for proportion read preparation. LECT. 25. S. 6, L.3: 
 for ammonia read ammonium; S. 10, L. 6: from calcium, read for cal- 
 cium. LECT. 32. S. 2, L. 5: For hydrometer, read hygrometer. 
 LECT. 33. S. 10, L. 2: Raleigh, read Rayleigh. LECT. 37. S. ii, 
 L. 7 : The — ous, read the anomalous. LECT. 40. S.7, L.4: ForNa27 
 
 read Na 23. LECT. 49. S. ii, L. 9: For 2 Ca O Cl = 183, read 
 Ca (O Cl)2 = 143; L. 10, for 7.629 read 5.96. LECT. 51. S. 9, L. 3: 
 Indicated read indicator. LECT. 60. S. 9, L. 6: Add B 160. LECT. 
 84. S. 2, L. 3: terrible read terribly. LECT. 86. S. 3, L. 5, admir- 
 able read admirably. 
 
 14 
 
IHE STUDENTS ATLAS 
 
 I. Chemists and Institutions; 
 
 Chemists: 17. In Old Kenii. — A Modern Temple of Chemistry 
 (Leipzig). iS, (hilileo Galilei. 19, Lavoisier. 20, 1 luvghens. 21, 
 Bovle. 22, Berzelius. 23, Liebig. 24, Bunsen. 25, Dumas. 26, 
 Faraday. 27. Berthelot. 28, Ilaidinger. 29. Padre Secchi. 30, 
 Lemery : \’an llelmont. 31, Pasteur; Volta. 32, Berthollet; Dalton. 
 33, Richter: Stas. 34, Mitscherlich : Hofmann. 35, Kirchhoff; 
 Kekule. 36, Claude Bernard; Moissan. 37, Chevreul; Court of 
 the Institut. 
 
 Institutions: 38, Palace of the Institute of P'rance; Ante-room 
 of the x\cademy of Sciences. 39, Meeting Room of the Academy; 
 The Institute of PTance, see pp. 37, 38, 39, 42. 39, Balance Room at 
 
 Breteuil (International Bureau of Weights and Measures). 4O; 
 Chemical Lecture Halls; Gratz^ Paris. 41, Chemical Laboratories; 
 Giessen; Leipzig. 42, Chemical Research Library: Secretary 
 Berthelot’s Room in the Palace of the Institute. 43, A page from 
 the Saint Mark Manuscript. 
 
 H. Prime Materials: 
 
 44, Galileo's Moons of Jupiter: Meteorite P'ield in Iowa. 45^ 
 Amana Meteorites, Hinrichs’ Collections. 46, Gems (models). 
 47, Veins. 48, Coal: Gold. 49, Vanilla; Milk. 50, Sea Salt: Rock 
 Salt. 51, Cryolite; Marble. 52, Cinchona: Magnetite. 
 
 HI. The Crystal World: 
 
 53, Microphotographs of Snow Crystals; Alexandrite Crystals, 
 Siberia. 54, Cubical Crystals, Rome de P Isle. 55, Calcite Crystals, 
 Hauy. 56, Beryl; Corundum. 57, Hematite. 58, Magnetite. 
 59, Cuprite: Garnet. 60, Zircon. 61, Topaz. 62, Topaz; Alex- 
 andrite. 63, Pyroxene. 64, Orthoclase; Anorthite. 65, Quartz; 
 Calcite. 66, 67, The Principal Crystal P'orms, according to Von 
 Kobell. 68, Blackboard Sketches of Common Crystals, and Student’s 
 Goniometer. 69, Sulphur Crystals (with their axes). 
 
IV. Diagrams : 
 
 70, Solubility in Water, Gay-Lussac. 71, Solubility in Water, 
 Etard. 72, Spectra of the Light Metals, Bunsen and Kirchhoff. 
 73, Chemical Reactions, Dry Way and Wet Way. 74, Boiling and 
 Fusing Points of Paraffins. 75, Boiling Points of Acids, Alcohol, 
 etc., (log. a). 76, Terminal Substitution, complex. 77, Terminal 
 
 Substitution, simple. 78, Boiling Point of Isomeric Ethers. 79, 
 Stas’ Determination of Silver Nitrate. 80, Ilinrichs’ System of the 
 Elements, showing their Composition. 
 
 V. Supplement: 
 
 385, Cleopatra’s Chrysopoeia, Berthelot; Chemical Valence, 
 Ilinrichs’, 1867. 386, Weight and Measure. 387, Gasometric 
 
 Apparatus. 388, Gas Manipulation. 389, Distilling and Extracting 
 Apparatus; Professor’s Stand, Chemical Laboratory, St. Louis 
 College of Pharmacy. 390, Micrographs of Ferments. 391, 
 Ilinrichs’ Chemical Elements, 1867. 392, The Dodecahedron; The 
 
 Pyritohedron. Hauy, Origin of Secondary Forms. 393, Daubree. 
 394, Structure and Properties. The Paraffins. 395, Structure and 
 Libration. Benzol. 396-7. Ilinrichs’ System of the Elements, 
 1867 and 1897. 398, Origin of the Periodic Law.” Atomic 
 
 Weights, Diamond Standard. 399^ Half a page from Hinrichs’ 
 Programme der Atom Mechanik, 1867. 400, A Look-Out to the 
 
 Old Pastures (67, i). 
 
 Portraits in the Text: 
 
 Agricola. Daubree. Lavoisier in Prison under the Reign of 
 Terror (full page). Priestly. Scheele. Woehler. 
 
IN OLD KEMI. 
 
 THE STUDENT’S ATLAS. 
 
 I. Chemists and Institutions. 
 
 A MODERN TEMPLE OF CHEMISTRY 
 
 17 
 
GALILEO GALILEI. 
 
 18 
 
LAVOISIER. 
 
 19 
 
HUYGHENS. 
 
 20 
 
BOYLE. 
 
 21 
 
BERZELIUS. 
 
LIEBiG. 
 
BUNSEN 
 
 24 
 
DUMAS, 
 
FARADAY. 
 
BERTHELOT. 
 
 27 
 
HAIDINGER. 
 
 28 
 
P. SECCHI. 
 
 29 
 
LEMERY. 
 
 VAN HELMONT. 
 
 30 
 
PASTEUR, 
 
 VOLTA. 
 
 31 
 
BERTHOLLET. 
 
 DALTON. 
 
 82 
 
RICHTER. 
 
 STAS. 
 
 33 
 
MITSCHERLICH. 
 
 HOFMANN. 
 
 :u 
 
KIRCHHOFF. 
 
 KEKULE. 
 
 85 
 
CLAUDE BERNARD. 
 
 MOISSAN. 
 
 ISOLATING FLUORINE IN THE SCHOOL OF PHARMACY, PARIS. 
 
 :U) 
 
COURT OF THE INSTITUTE. 
 
 CHEVREUL, 
 
 AT THE AGE OF ONE HUNDRED YEARS. 
 
 87 
 
PALACE OF THE INSTITUTE. 
 
 ANTEROOM OF THE ACADEMY. 
 
 38 
 
MEETING ROOM OF THE ACADEMY. 
 
LECTURE BY LEMERY, PARIS, 1680. 
 40 
 
LIEBIG’S LABORATORY, GIESSEN. 
 
 IN KOLBE’S LABORATORY, LEIPZIG 
 
 41 
 
V*ffi Xu t A- 4 ' t -trl t “TH jjlH \ nni m e r K E t juuVi uu *>4 1 i{*n t nr ; c 
 
 { V^f|sXXOjJLlCt'TtL)W<^ 1 ^ 0 to"<^ajJ 4 - H C 
 
 CTJJUU NMC 4 >l?VCU<|>l^ '.'• 
 
 0 'XJ 
 
 C, CE^Nhhh Xj* p c 
 K Kf 0 Mfl C<{>iUNONJLmA.I&PC 
 
 ^ Ytc|>a.f-Hju jsj nXfk-tj ft c 
 
 Xj’Ht"Try'.peiccr, 2 xHpc 
 ^ Ai:{>p 3 b^j'vM 4 >afCcj 5 c|*’x^^Kot 
 ^ EjJULHCC-riX'BtUK* 5 EAxci''rH^flC 
 
 ^ V> Y* C 0 C 
 
 LOV pNHJUJL 
 
 0 1 KiiCisrxjuyi 
 
 VfdKOTjXa^ 
 
 h 
 
 4 a 
 
 jLt.xxxr^xx| y c 0 Y- 
 ^ ^ rv“p P 
 ^ JLjn. p-v mi 
 
 ^ JL^rrp Y-pwH juUL 
 
 r\rjoX^ Y'COICOI^X 
 gjJL? rVf ft CJCEt«iJY"JlUMCC v 
 
 ^ * I 0 fCU'c t-ru Pt 
 
 ^XiAKoCK-^ntpoc-^ ^ K^t.n^'pv-rH 
 
 ? ^ KXIC l-TH f OY^Pt M HJlUL 
 
 ^ MH JULA- * ’ * 
 
 juuj b Xj nr rn 
 jlldTm b 2^.0 *x*aLXKdC 
 ju-OTs.! BJXDnrp mhjl-Ul 
 juLi X 1 B :?vo c K e ic Arr juu H 0 c 
 
 tCJJCt-rHfOl 
 
 5 KJLit tTHPt nr-m 'OLPAi. 
 
 9 'V^j 7 \Konr"rrt tBJ\X S 
 
 ^ g HX£C l VK Pot ^CIKA^i-aMd-r 
 
 ^ ^KOttceKi-TLU^oe j, of 
 
 PNfv'KHM'trj.rt Kijvj 
 
 0 M Azjrrry 0 Ni 
 
 tow -d- B 
 
 ^ i^i low W T-O W 
 
 ‘.V 
 
 f p*Y^p W HJlUL 
 
 f i! 2 ui j» o nr TTtnpA-X.o m 
 ^ Ci:^H P dnr lot, 
 
 ^ Bac 
 
 JLcb p r f p\H h 40 M 
 
 ALCHEMISTIC SIGNS OF THE METALS. 
 
 SAINT MARK MANUSCRIPT. FROM BERTHELOT. 
 
 48 
 
GALILEO SHOWING THE MOONS OF JUPITER TO THE 
 SENATORS OF VENICE. 
 
 THE STUDENT’S ATLAS. 
 
 THE GREAT IOWA METEOR, FEBRUARY 12, 1875. 
 44 
 
45 
 
 AMANA METEORITES. Hinrichs’ Collections. 
 
GEMS. 
 
 46 
 
VEINS, FREIBERG, SAXONY. 
 
 ONE-FIFTIETH NATURAL SIZE. 
 
 47 
 
COAL MINING, FRANCE. 
 
 EPINAC. 
 
 GOLD MINING, TRANSVAAL 
 
 ZULU MINERS. 
 
 48 
 
VANILLA. 
 
 JARDIN DES PLANTES, PARIS. 
 
 MILK. 
 
 CENTRAL PLATEAU, FRANCE. 
 
 49 
 
SEA SALT. FRANCE. 
 
 BOURG DE BATZ, BRITTANY. 
 
 ROCK SALT QUARRY, SPAIN. 
 
 CORDONNA VALLEY, PYRENEES. 
 
 50 
 
CRYOLITE, GREENLAND. 
 
 ARKSUT FJORD. 
 
 MARBLE, ITALY. 
 
 MONTE ALTISSIMO. 
 
 51 
 
CINCHONA, PERU. 
 
 BARK GATHERING. 
 
 MAGNETITE QUARRIES, ELBA. 
 
 CAPE CALAMITA- 
 
 r)2 
 
MICROPHOTOGRAPHS OF SNOW STARS. 
 
 THE STUDENT’S ATLAS. 
 
 III. The Crystal World. 
 
 ALEXANDRITE CRYSTALS. SIBERIA. 
 58 
 
I.e CviiEim lHexaedre et ses Afocii/iaih’oiu 
 
 54 
 
 ROME DE LISLE. 
 
1’aJITIF. 1)E RAlS(miST>:MKNT 
 
 55 
 
 RENE-JUST HAUY. 
 
TAF Ig 
 
 56 
 
 BERYL. CORUNDUM. 
 
57 
 
 HEMATITE. HEMATITE. 
 
TAP XLX 
 
 58 
 
 MAGNETITE, MAGNETITE, 
 
59 
 
 CUPRITE, GARNET, 
 
TJF XlVIll 
 
 60 
 
 ZIRCON. ZIRCON. 
 
T/IF XKXMll (a) TAF XXXV/fl (if 
 
 61 
 
 TOPAZ. TOPAZ. 
 
TAF XXWUl (f) 
 
 62 
 
 TOPAZ. ALEXANDRITE. 
 
63 
 
 PYROXENE. PYROXENE. 
 
64 
 
 ORTHOCLASE. ANORTHITE. 
 
< 2 3 4 > 6 7 
 
 16 17 IS <9 20 
 
 < 2 3 4 5 6 
 
 7 8 9 40 H 12 13 
 
 G5 
 
6G 
 
67 
 
CRYSTAL DESCRIPTION, 
 
69 
 
THE STUDENT’S ATLAS. 
 
 IV. Diagrams. 
 
 70 
 
71 
 
SPECTRA OF THE LIGHT METALS. 
 
 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 ICO 170 
 
 blau violet 
 
 Spcctraltafol nacli Kirclihoff und Bunsen, 
 
CHEMICAL REACTIONS. 
 
 DRY WAY. VVET WAY. 
 
74 
 
 BOILING AND FUSING POINTS OF PARAFFINS. 
 
BOILING POINTS OF ACIDS, ALCOHOLS, Etc, 
 
76 
 
 TERMINAL SUBSTITUTION, COMPLEX. 
 
uhstitutLOTi terminale 
 
 ( i 
 
 TERMINAL SUBSTITUTION, SIMPLE. 
 
78 
 
 BOILING POINT OF ISOMERIC ETHERS. 
 
nitrate - STas, 
 
 79 
 
 STAS’ DETERMINATION OF SILVER NITRATE. 
 
80 
 
1. CHEMISTRY AND AL KEMI. 
 
 1. Chemistry treats of the changes of matter. It was 
 first practiced by the inhabitants of Kern or Kemi (Egypt). 
 The very name of our science thus proclaims its ancient origin. 
 Atlas, p. 17. 
 
 To understand this definition fully implies to have studied 
 the SCIENCE and practiced the ART of Chemistry. Here it 
 must therefore suffice to explain the words used in the definition. 
 
 2. MATTER is that which constitutes all things. We all 
 know some metals, stones and ores, representing the inani- 
 mate kingdom of nature. Flowers and fruits are vegetable, 
 milk, blood, meat and bone are animal things. Chemistry 
 deals with the changes of matter from all three kingdoms of 
 nature. Nor is Chemistry restricted to materials of this earth ; 
 the material of the sun and the stars has been successfully 
 investigated during the last forty years. 
 
 3. Motion and division of matter are called PHYSICAL 
 processes ; they do not affect the nature of the material itself. 
 The power to produce such motion or division may be great, 
 as witnessed on our railways and in our mills. The immense 
 ball, thrown several miles from the modern cannon, does not 
 change its material nature in this act of motion; however, the 
 charge of powder has disappeared, it has undergone a chemical 
 change. 
 
 4. But if that ball be left exposed to the air, the water or 
 the earth, it will gradually be changed into a brownish, non- 
 coherent mass,' which we call rust. Smaller and thinner iron 
 things are quite rapidly changed to rust throughout. Objects 
 of copper turn green under like conditions. Gold remains 
 unchanged. The change of limestone to lime in the kiln is 
 also a radical one, practiced from time immemorial to make 
 mortar. Such are chemical CHANGES of matter. 
 
82 
 
 LECTURE 1. 
 
 5. Organic matter, that is vegetable and animal substance, 
 chars when heated while the air is partly excluded. Inflam- 
 mable materials pass off during this process. A specially 
 offensive odor is noted when animal matters are charred. 
 Thus it is generally easy to distinguish mineral, vegetable and 
 animal materials by a simple CHEMICAL TEST. 
 
 6. All nature is one boundless CHEMICAL LABORATORY, 
 and the most skillful of all chemists are the plants and animals. 
 From the same soil, water and air, and by the power of the 
 same sunbeam, PLANTS produce not only their diverse materials 
 such as wood, leaf, flower and fruit in general, but each kind of 
 plant produces some more valuable chemical specialty, such as 
 the fragrance of the rose, differing from that of the lily; the 
 potency of the poppy, differing from that of the conium. 
 Atlas, p. 49. 
 
 7. In a like manner, every animal is a most wonderful 
 CHEMICAL FACTORY. The beginner should be impressed 
 with such primary fact as the chemical change of grass and 
 water into milk. Surely, grass, water and air are the only 
 raw materials accessible to the cow in her pasture. And what 
 a remarkable chemical product is the milk produced, containing 
 butter, cheese, sugar, and mineral salts dissolved and sus- 
 pended in water! Atlas, p. 49. 
 
 8. Seeing the INFINITE DIVERSITY of organic matter pro- 
 duced from the identical simple raw materials of soil, water 
 and air, we can understand that profound thinkers, twenty 
 five centuries ago, considered all matter essentially one in kind. 
 For about a century this idea has been generally derided by 
 chemists. It does not seem to us that the ancient sages were 
 greatly in error. 
 
 9. But if all matter be essentially one, it seems possible 
 that any material might be made by art if only sufficient 
 knowledge had been acquired. Hence ancient chemists 
 (ALCHEMISTS) endeavored to make gold from common metals, 
 and tried to produce an elixir to give health and prolong life. 
 
CHEMISTRY AND AL KEMI. 
 
 8:j 
 
 Working to realize these high ideals, they laid the foundations 
 of CHEMICAL ART AND SCIENCE, the two equally important 
 parts of CHEMISTRY. The science we present in the lecture 
 hall, the art we practice in the laboratory. Atlas pp. 40, 41. 
 
 10. Chemical science has ever enabled chemical art indi- 
 rectly to make gold, and thus to REALIZE THE IDEAL OF 
 THE ALCHEMIST. Clay was converted into costly porcelain; 
 coal tar was changed into the colors of the rainbow, and 
 apparently worthless ores are now yielding gold by the million 
 dollars in Transvaal and in Colorado. Atlas, p. 48. 
 
 11. Chemistry is also approaching the second ideal of its 
 founders. The active remedial principles have been extracted 
 from many plants, and even new remedies have been pro- 
 duced by direct synthesis, the chemist imitating the work 
 done by the living cell! Moreover, practical hygiene is main- 
 ly chemical. Surely, Chemistry does give health and pro- 
 long life. 
 
 12. Until it shall be deemed proper to deride Columbus for 
 having discovered America while he sought the Indies, we 
 will not join those who deride the early workers in Kemi for 
 having held ideals too high to be fully realized in three 
 thousand years. In Chemistry, as everywhere else, the 
 highest ideals are the best; the distant star is a better guide 
 than the near ignis fatuus. Sic itur ad astra. 
 
 Notes. Deeming it essential to keep the text as brief and clear as 
 possible, collateral and explanatory matter, aiding in the understanding 
 of the topic presented, is appended in the form of short notes, precisely 
 as explanations are given at the lectures, but not considered as part of 
 the subject itself, once that being understood. The notes will be prefaced 
 by a numeral referring to the paragraph for which they are intended. 
 
 I. Chemistry, in English, is commonly pronounced Kem-istry; sig- 
 nifying knowledge pertaining to Kemi. Chemistry is called Kemi in 
 Danish, Chemie in German and Chimie in French. 
 
 6. Among the various plants represented in the cut as growing in a 
 glass-house of the Jardin des Plantes at Paris, the climbing Vanilla will 
 
84 
 
 LECTURE 2. 
 
 be noticed, showing flower and the valued fruit, also numerous pendent 
 air roots. 
 
 7. These Chemical factories (cows) are exceedingly numerous and 
 their product aggregates millions a year in every country. When no 
 longer wanted for milk production, these factories are let alone, and pro- 
 duce meats and fats, hides and bones, all prime materials of the highest 
 importance. England imports for 40 million dollars butter alone a year. 
 
 10. The new cyanide process with reduction by electrolysis makes it 
 possible to work low grade ores profitably. The Zulus do the mechani- 
 cal work of drilling, shown p. 48; dynamite does the rest. The Trans- 
 vaal gold deposit is not a vein, but a stratum, the onl}' stratified gold 
 deposit in the world. 
 
 2. WEIGHT AND MEASURE. 
 
 1. Any body or thing occupies some definite amount of 
 space, called its bulk, measure or VOLUME. It also exerts 
 some definite amount of pressure upon its support; this pres- 
 sure is called its WEIGHT. Weight and measure are the only 
 two general properties which matter possesses. 
 
 2. By adopting convenient UNITS, both weight and volume 
 can be expressed by numbers. The standard units are the 
 KILOGRAMME and the METER. Exact copies thereof are 
 made at the International Bureau of Weights and Measures, 
 in the Pavilion Breteuil at Saint-Cloud, in southwestern Paris. 
 This Bureau is jointly maintained by over twenty countries, 
 including the United States and Great Britain. Atlas, p. 39, 
 shows the Balance Hall of this Bureau. 
 
 3. The metrical standards were adopted in France a cen- 
 tury ago, to secure natural units and uniformity; even towns 
 having distinct units at that time. The meter was intended 
 to be the ten -millionth partmf the earth’s quadrant passing 
 through Paris. The kilogramme was intended to be the pres- 
 sure of a tenth -meter cube of water at its greatest density. 
 
 4. Modern determinations have shown that the quadrant 
 really is about 10.001.900 meters and that the kilogramme 
 exceeds the defined amount by something less than one ten- 
 
WEIGHT AND MEASURE. 
 
 85 
 
 thousandth part. The actual material STANDARDS, made a 
 century ago are, however, retained unchanged by the Interna- 
 tional Commission; the original definition being sufficiently 
 complied with for practical purposes. 
 
 5. The system of numeration in universal use being 
 DECIMAL, the units of weight and measure must also be 
 divided and multiplied by tens to avoid useless reductions. 
 The sub-multiples are distinguished by Latin prefixes (deci, 
 centi, mini), while the multiples are designated by greek pre- 
 fixes (deka, hecto, kilo). The mega is used for very large 
 (million) and the micro for equally small (millionth) values. 
 Thus the micrometer or micron (/^) being the thousandth of a 
 millimeter, is the usual unit for microscopic objects. 
 
 6. THE BALANCE is the instrument for weighing. It con- 
 sists of a light, rigid beam, resting by means of a transverse 
 edge on a hard smooth plane. Two smaller edges at the ends 
 of the beam support like planes to which the pans are attached. 
 The distances from the outer to the central edge (the arms) 
 must be equal. 
 
 In good (prescription) balances, edges and planes are of 
 hardened steel ; in the analytical balance, the planes are of 
 agate ; in the best balances, the edges are also made of agate. 
 
 7. Weights are made in sets, containing one 5, one 2 
 and two 1 for each digit, except the last, for which commonly 
 two 2 and one 1 are given to complete the 10 and allow a check. 
 f;rom one gramme up, the weights are usually turned brass; 
 for subdivisions of the gramme, platinum foil is used. Each 
 single weight is fitted to its special place in the box holding 
 the set. Chemical weights must be handled by forceps only, 
 never touched with the fingers. 
 
 8. In WEIGHING, the body is placed on the left pan, and 
 weights' are applied in the order of their magnitude on the 
 right pan. By a simple mechanism, the beam is brought into 
 action only for an instant to see whether the weights on the 
 pan are too heavy or insufficient. Below the centigramme. 
 
LECTURE 2. 
 
 the beam is permitted to oscillate, the balance case being 
 closed to prevent air currents. If the oscillations of the pointer 
 are equal on both sides, the weighing is completed. 
 
 9. Balances and weights obtained from reputable makers 
 will stand all TESTS warranted by the price paid. All details 
 about these matters belong to the course in practical chemistry. 
 
 The balance being the most sensitive and accurate instru- 
 ment of all, the chemist checks his volume measures by 
 weighing them empty and filled with water up to mark. Every 
 cubic centimeter (cc) should correspond to a gramme (gr.) 
 
 10. For the ready measurement of volumes the chemist 
 uses sets of glass vessels accurately graduated (BURETTES 
 and CYLINDERS) or provided with a mark filled up to which 
 they hold a definite amount (FLASKS and PIPETTES). 
 Graduated cylinders with ground glass stoppers are also called 
 MIXING JARS. The burettes are either provided with a rubber 
 tube and spring clamp (Mohr’s), or with a perforated ground 
 glass stopper (Geissler’s) for use with corrosive liquids. 
 
 11. Common experience shows that bodies differ greatly in 
 density; lead is heavy, chalk is light, cork even lighter than 
 water. 
 
 The SPECIFIC GRAVITY (G) of a substance is the weight, 
 in grammes, of one cubic centimeter thereof. The specific 
 gravity, carefully determined, is an important characteristic of 
 matter, enabling us to distinguish otherwise similar bodies. 
 Thus one cc of lead weighs 11.35 gr. ; or lead is character- 
 ized by its G being 11.35. 
 
 12. To determine the specific gravity of any body, ascer- 
 tain its weight (w) in grammes and measure its volume (v) 
 in cubic centimeters; dividing the volume into the weight, we 
 evidently obtain the weight of one cubic centimeter, that is 
 the value of G. This process applies to all bodies; the special 
 methods of measuring vary with the nature of the body. A 
 ten gramme flask holds 7.91 gr. of absolute alcohol; hence 
 G is 0.794 for this liquid. 
 
3. SOLIDS AND FLUIDS. 
 
 1. Matter presents itself in three distinct forms, namely as 
 solid, liquid and gas. These forms are also called the three 
 STATES OF AGGREGATION. Ice, wood, iron, copper, are 
 solids; water, oil, alcohol, are liquids. The most common gas 
 is atmospheric air. 
 
 2. Hold any SOLID body in varying positions, especially 
 in reference to the vertical, and no change in either shape 
 (form) or bulk (volume) of the solid will be noticed. That is, 
 solid bodies possess a form and volume of their own. In other 
 words, the volume and form of a solid are fixed (constant) 
 quantities. 
 
 3. A LIQUID contained in any glass vessel, handled in the 
 same way, will exhibit in all positions a free surface which is 
 plain and level, otherwise it will conform to the shape of the 
 containing vessel. If the volume of the liquid is measured at 
 the beginning and at the close of such experiment, it will be ^ 
 found to have remained unchanged. Thus liquids have a fixed 
 volume, but no form of their own. 
 
 4. The FREE SURFACE of the liquid shows near the walls 
 of the containing vessel a curved surface ; concave for water, 
 convex for mercury in glass vessels. If a tube be inserted, 
 the liquid will rise or sink so much the more as the tube is 
 more narrow or hair like (capillary). Hence the cause of this 
 deviation from the plane surface is called CAPILLARITY. 
 
 5. Only vessels sufficiently wide will show the true plane 
 and level free surface of the liquid. To FILL TO MARK or 
 read the volume on a graduation, the eye should be brought 
 exactly in the height of this surface. If the vessel be too 
 narrow, the lower (for mercury the upper) curved surface 
 should be tangent to the mark of capacity or graduation. 
 
 6. The free surface of the same liquid contained in two 
 VESSELS, COMMUNICATING by means of a sufficiently wide 
 tube, stand always in the same level, however the position of 
 
LECTURE 3. 
 
 the vessels may be changed. This is readily seen by using 
 the burette with reservoir, or our gas burette open, and with 
 any liquid, including mercury. 
 
 7. If the exit tube of the gas burette be closed, the free 
 surface of the liquid in the burette and reservoir will no longer 
 be in the same level; it will stand low in the burette if the 
 reservoir is raised, and vice versa. Consequently the AIR in 
 the burette resists the pressure of the liquid in the reservoir, 
 and expands when the reservoir is lowered ; it is a substance 
 or body. 
 
 8. Thus the air in the closed gas burette has neither 
 volume nor form of its own ; its form is that of the containing 
 vessel, and its volume is dependent on the pressure to which 
 it is subjected. Such a body is called a GAS. 
 
 Liquids and gases flowing freely from one vessel to another, 
 are also designated by one term FLUID. A liquid is a fluid of 
 fixed volume; a gas is a fluid of variable volume. 
 
 9. A gas may be handled almost as readily as a liquid, by 
 means of the pneumatic trough, flasks and cylinders. The 
 PNEUMATIC TROUGH is simply a wide vessel containing a 
 liquid (water, mercury) in which cylinders, flasks, etc., can 
 be filled with the liquid and inverted; they will remain 
 filled, and receive and retain gas from any other vessel or 
 delivery tube. A few experiments make this familiar. See 
 also plate of gas apparatus. 
 
 10. A gas burette filled with mercury and provided with a 
 stop -cock at the top can be used as BAROMETER and as a 
 mercurial air pump. 
 
 By raising the reservoir, fill the burette to a little above the 
 stop -cock, then shut this. Now lower the reservoir. The 
 burette will remain filled with mercury so long as the surface 
 of the mercury is not more than 76 cm lower than the stop- 
 cock. If lowered more, the VACUUM will appear in the 
 burette, and the column of mercury will remain invariably 76 
 cm. This corresponds to Torricelli’s experiment (1642). 
 
SOLIDS AND FLUIDS. 
 
 89 
 
 11. To use the burette as mercury AIR PUMP, its stop-cock 
 must be perforated lengthwise and connected with the receiver 
 to be exhausted. By a simple turn of the stop-cock, the 
 burette can now be closed (A), or communicate with the air 
 (B) or with the receiver (C). In position (B), fill the burette 
 with mercury, by raising the reservoir; then close (A) and 
 lower reservoir 76 cm; now. connect with receiver (C) ; then 
 turn to B, raise reservoir and drive out air. Continue these 
 operations, and the air in the receiver will rapidly be reduced 
 in amount. 
 
 12. If the burette be equal to the capacity of the receiver, 
 the amount of air withdrawn at each complete motion is one 
 half, leakages neglected. Ten motions would reduce it to the 
 thousandth part of the original. 
 
 If a U tube with perforated stoppers and a capacity of from 
 50 to 100 cc be exhausted, it will show a loss in weight of 
 over one milligram per cubic centimeter. This evidently is 
 (approximately) the WEIGHT OF THE AIR. 
 
 Notes 3. Before filling the vessel, film it. that is, move a small 
 amount of the liquid around in the vessel so as to cover the inside with a 
 film of that liquid; then let run and drip out all that will flow. If the 
 vessel was not filmed, the volume of the liquid used in the experiment 
 would apparently have diminished slightly. 
 
 4. FUSING AND BOILING. 
 
 1. Solid ICE brought into a warm room melts or fuses, 
 being converted into liquid WATER. The latter, heated in a 
 flask, soon begins to boil; while condensed vapor (liquid drops) 
 issue at the top, the flask above the water looks as if it con- 
 tained air, that is the true STEAM, water in the gaseous state. 
 
 Solid' IODINE is also readily melted and converted into 
 beautiful violet vapor. The corresponding experiment with 
 SULPHUR requires care, the vapors burning with explosive 
 violence. 
 
90 
 
 LECTURE 4. 
 
 2. In general, a fusible solid, upon heating, will melt, and 
 a volatile liquid will boil. By decreasing the heat, the vapor 
 will again liquefy (condense), and the liquid will solidify 
 (frequently crystallize). Thus the state of aggregation of a 
 substance depends not only on the nature of that substance, 
 but essentially also on the temperature to which the substance 
 is exposed. 
 
 3. Heat does not change gases, except in bulk. Grasp the 
 receiver of our gas burette firmly with the hand, and the 
 motion of the liquid will show. that the air EXPANDED. With- 
 drawing the hand, the air returns to exactly its original volume. 
 This apparatus accordingly is a sensitive AIR THERMOMETER. 
 With porcelain and platinum receivers, it permits the determi- 
 nation of very high and also very low degrees of heat. Com- 
 mon thermometers contain mercury or alcohol. 
 
 4. Inserting the bulb of such a thermometer into crushed 
 ice, the thermometer will first fall rapidly, then more gradually, 
 and finally remain perfectly stationary or fixed, so long as a 
 reasonably large amount of ice remains. This FIXED POINT 
 of temperature at which ice melts is called the freezing point, 
 and marked zero. In the same manner, boiling of water is 
 found to take place at a fixed point, called the boiling point, 
 which is marked 100. 
 
 5. The interval (volume in burette or in thermometer tube) 
 is divided into 100 equal parts, called DEGREES of tempera- 
 ture. For air thermometers this division is continued 
 indefinitely upwards and downwards. 
 
 6. If the reservoir be a 100 cc pipette melted off at the 
 mark, and connected by narrow tube with (mercury) gas 
 burette, and the reading of the burette be taken while the 
 reservoir (bulb) is packed in melting ice and also when sur- 
 rounded by steam of boiling water, the EXPANSION will be 
 found equal to 36 cc. Accordingly it is 0.36 cc per degree for 
 100 cc. Gay-Lussac. 
 
FUSING AND BOILING. 
 
 91 
 
 7. In the same manner, the FUSING POINT (F) of any 
 solid is that fixed degree of temperature at which the solid 
 changes to a liquid; so long as any notable amount of solid is 
 left, the thermometer will remain stationary. If the crucible 
 with the molten mass is set aside to cool, the crust broken 
 and the remaining liquid poured out, the wall will often be 
 found studded with beautiful crystals. Examples: Sulphur; 
 Bismuth. 
 
 8. When heating a volatile liquid in a flask provided with a 
 thermometer, the temperature will first rapidly rise, then 
 gradually become stationary, when the liquid will begin to 
 boil, forming bubbles of gas throughout its mass. This fixed 
 temperature is the BOILING POINT (B) of the liquid. When 
 the vapors of the liquid are inflammable, the flask must be 
 connected with a condenser. EVAPORATION is the forma- 
 tion of vapor at the surface of the liquid only. 
 
 9. A CONDENSER consists of an inner tube through which 
 the vapors pass from the bulb or flask to the receiver, sur- 
 rounded by an outer tube through which a current of cold water 
 is kept flowing in the opposite direction of the flow of the 
 vapors. Accordingly,' the chance of their condensation in- 
 creases as they pass on. The Liebig condenser is the most 
 common form in use. Atlas, p. 23. 
 
 10. This entire process, comprising the change of liquid 
 into vapor, followed by the condensation of the vapor to a 
 liquid, is called DISTILLATION. All non-volatile matters will 
 remain in the flask; hence distillation enables the chemist to 
 separate the volatile from the non-volatile matters. 
 
 If the vapors condense to a solid, the operation is called 
 SUBLIMATION. Example: Iodine. 
 
 If the thermometer remains stationary, it marks the boiling 
 point (B) of the pure liquid. If the thermometer is not sta- 
 tionary, the substance is a mixture. 
 
 11. In such cases, the process of FRACTIONAL DISTILLA- 
 TION will separate these different substances and yield nearly 
 
92 
 
 LECTURE 5. 
 
 pure materials. The portions or fractions of the distillate, pas- 
 sing over between definite degrees of temperature, are kept 
 separately; these fractions are again run through the distilling 
 apparatus in succession, always removing the new fractions 
 when the same limits of temperature are obtained. After four 
 or more such runs, the fractions often pass over without change 
 in temperature, and thus represent single substances. 
 
 12. These two fixed points F and B are most CHARAC- 
 TERISTIC numbers for a given substance, often readily distin- 
 guishing otherwise closely resembling materials; hence they 
 form, together with G, the most important part of the scien- 
 tific description of a given substance. If the material has no 
 such fixed points, it is thereby proved to be impure, and 
 should be subjected to fractioning, to separate it into its prin- 
 cipal ingredients. 
 
 5. FURNACE AND BLOWPIPE. 
 
 1. HEAT not only produces the 'physical changes of volume 
 and state of aggregation, but it also is one of the common 
 causes of CHEMICAL CHANGES. Inversely, the latter often 
 produce heat. This is especially the case in the general pro- 
 cess of COMBUSTION, a chemical action of combustible and 
 air. When either combustible or air is withdrawn, com- 
 bustion ceases. 
 
 2. WOOD is the oldest combustible used; it produces first 
 a flame or blaze, and when the volatile combustible material 
 is burnt, the intensely glowing coals remain. Such a fire is 
 too unsteady for most chemical purposes. Hence, wood first 
 is charred, by slowly burning with limited supply of air, and 
 the resulting CHARCOAL is used. It was the only com- 
 bustible of the early chemists. 
 
 3. In modern days, combustible liquids and gases have 
 come into general use in laboratories. In the days of Berzelius, 
 ALCOHOL was used, especially in the excellent lamp with 
 
FURNACE AND BLOWPIPE. 
 
 93 
 
 double draft, constructed by him. For many years, illumi- 
 nating gas — the volatile part of bituminous coal— has been 
 accessible nearly everywhere; it is the best combustible for 
 most laboratory purposes. Where gas cannot be had, gaso- 
 line is frequently used. Atlas, p. 22. 
 
 4. An ordinary gas flame is brightly luminous, but not very 
 hot; a cool vessel held over it will be soiled with soot. For 
 heating purposes, a gas flame evidently needs a more abundant 
 supply of air. In the BUNSEN BURNER, this object is per- 
 fectly attained, by surrounding the small gas jet with a wide 
 air tube or chimney, open below. Such a burner gives a tall, 
 steady, almost invisible flame, very hot and depositing no soot. 
 Glass tubes are bent and drawn easily in this flame. Atlas, 
 p. 24. 
 
 5. The Bunsen Burner is used in all laboratories the world 
 over, singly for ordinary work, grouped into FURNACES for 
 heating larger forms of apparatus, such as tubes and crucibles. 
 These furnaces are provided with fire clay slabs, disks, wide 
 tubes, to support or encase the vessel, so that the heat 
 may be concentrated upon the vessel and not dissipated to the 
 surroundings. Example: The so-called combustion furnace 
 for elementary analysis 
 
 6. The highest degree of heat can only be obtained by 
 burning a large amount of gas completely by means of a 
 correspondingly large supply of air. Accordingly, the gas tap 
 
 must be large, and the air 
 must be forced by a bellows 
 into the center of the flame. 
 Glass is readily fused in 
 
 Glassbiowers in ancient Egypt SUCh SL BLAST FLAME, and 
 
 platinum crucibles are brought to white heat almost instantly. 
 Forms of blast and blast furnaces are very numerous, many 
 makes being most excellent. 
 
 7. By means of the chemical BLOWPIPE, all the effects of 
 furnaces may be obtained on a small scale; it is truly a 
 
94 
 
 LECTURE 5. 
 
 miniature furnace. After a little careful practice, an intensely 
 hot flame may be maintained steadily and on a minute sample 
 produce almost instantly the varied effects of furnaces. The 
 chemical blowpipe was pefected by Swedish chemists of last 
 century and became universal through BERZELIUS. Atlas, 
 P..22. 
 
 8. The main difficulty in using the blowpipe consists in 
 keeping up a steady flame independent of the regular work of 
 the lungs. TO INHALE AND BLOW at the same time seems 
 impossible; but it is quite easily done, if the respiratory out- 
 let be rigidly limited to the nose (which was specially made 
 for that) while the cheeks fully distended, by their elasticity 
 keep up the flow of the small amount of air required for 
 the blowpipe. 
 
 9. Where much blowpipe work is to be done, the inner 
 tube of a so-called COMPOUND BLOWPIPE may be connected 
 with foot bellows, while the outer tube is connected with the 
 gas tap. With such an apparatus, blowpipe work may be 
 exhibited to a class during lectures. 
 
 10. In every good blowpipe flame THREE REGIONS are dis- 
 tinguished. At the luminous, bluish point the heat is greatest; 
 it is the FUSING POINT (borax beads, flame colorations). 
 Beyond that point is the OUTER FLAME, assisting combus- 
 tion and producing calcination of metals; within is the INNER 
 FLAME, in which the calx may be reduced again to the metallic 
 state. Example: Lead, supported on charcoal ; flame colora- 
 tions of nitre or salt; borax beads with copper or cobalt calx. 
 
 11. As SUPPORT for substances while being heated, glass, 
 porcelain, platinum and carbon, are most generally used for 
 experimental purposes. Fireclay and bone ash are also em- 
 ployed. 
 
 The best chemical glass is the so-called Bohemian glass, 
 which is light, hard and difficultly fusible; when heated in a 
 Bunsen flame, it is not quick to color it, and first tinges it 
 purple only. Tubes of such glass are most useful. 
 
METALS, OLD AND NEW. 
 
 95 
 
 12. Porcelain in the form of dishes, crucibles and tubes, 
 will stand a higher heat than glass. Platinum vessels and 
 carbon (charcoal and graphite) are used at the highest 
 temperatures. 
 
 For blowpipe work, hard glass tubing, platinum wire and 
 foil, and good charcoal are all that is required. The properties 
 recognized by blowpipe work are commonly called PYRO- 
 GNOSTIC PROPERTIES (Berzelius). 
 
 Note. — In this lecture, as in all others, the objects referred to are 
 abundantly exhibited, and the operations mentioned, are pi'oduced 
 before the class. Thus work on glass (especially tubing) and metals v 
 is exhibited; flame colorations and beads are shown. The manganese 
 bead is amethyst in the outer, colorless in the inner flame. 
 
 6. METALS, OLD AND NEW. 
 
 1. Two substances have attracted the attention of man in 
 the earliest times, and continue to busy his thoughts to-day. 
 The one is and ever has been most precious to him, so that 
 he is willing to accept a small portion thereof as reward for his 
 labors. The other first was his heaven-sent weapon, has 
 become the tool of his hand and mind; he even endeavors 
 with it to build higher than Babel. 
 
 2. GOLD is the one of these bodies. Hardly any rich 
 gold deposit is left in the long inhabited countries, but history 
 and myth show they were once as rich in gold, as California 
 and Australia in the middle of this century. Gold has the 
 brilliant luster (metallic) in a high degree; its color is yellow- 
 .ish; its density almost twenty times that of water; when 
 struck a blow, it yields (is malleable). Fire does not change 
 it; it is rare, it cannot be overlooked or mistaken. It is gold. 
 
 3. Primitive man also found another metal (luster, mal- 
 leable, heavy), in large lumps, grey in color. We have record 
 of early falls from heaven of such masses of malleable IRON 
 
9G 
 
 LECTURE 6. 
 
 at Aegos Potamos on the Bosphorus. Such METEORITES are 
 represented on ancient medals and coins. In the time of 
 Homer iron was prized with gold. Many large meteoric iron 
 masses have been found in Mexico, near the Texas border; 
 also in Southeast Africa, where the natives worked them into 
 tools. (J. Herschel). Atlas, pp. 44, 45. 
 
 4. To-day, THE WORLD produces 175 tons' of GOLD a 
 year (49 in U. S., 46 Australia, 15 Transvaal, 40 Russia in 
 1890; now Transvaal much more). In the same year (1890) 
 the total production of IRON was 27 million tons, (U. S. 10, 
 England 8, Germany 5, France 2). This enormous increase 
 in the production of iron is directly due to chemical progress. 
 The price in Germany was (1890) down to 12 dollars a ton. 
 
 5. THE UNITED STATES produced, in 1895, 71 tons of 
 GOLD worth 47 million dollars, and 9.5 million tons of IRON 
 worth 105 million dollars. Accordingly, the ratio of the 
 weights of iron and gold possessing equal value is 60,000 to 1. 
 With the progress of smelting this ratio has been rapidly in- 
 creasing during the ages, and is bound to increase still more. 
 
 6. In addition to these two METALS, the ancients knew 
 only five other bodies possessing metallic luster and mallea- 
 bility; namely silver, copper, tin, lead and mercury. For 
 almost two thousand years these SEVEN METALS were com- 
 pared to the seven planets and designated by the planetary 
 signs: Gold, Sun; silver. Moon; quicksilver. Mercury; cop- 
 per, Venus; iron. Mars; tin, Jupiter; lead, Saturn. Terms in 
 common use still remind us of this comparison. Atlas, p. 43. 
 
 7. Chemists now designate the metals by the CHEMICAL 
 SYMBOLS introduced by BERZELIUS and consisting of the 
 first and the characteristic letters of their latin (or latinized) 
 name. Thus gold (aurum). An; silver (argentum), Ag; 
 quicksilver (hydrargyrum), Hg; copper (cuprum), Cu; iron 
 (ferrum), Fe; tin (stannum), Sn; lead (plumbum), Pb. In 
 a like manner, sulphur is represented by S, Carbon by C, and 
 Iodine by lo. Atlas, p. 22. 
 
METALS, OLD AND NEW. 
 
 97 • 
 
 8. The seven old metals remain even to-day THE GREAT 
 METALS in the economic life of nations. Thus the United 
 States produced in 1895 in all 270.5 million dollars in metals, 
 of which iron 105.2; silver 60.8; gold 47.0; copper 38.7; lead 
 10.7; zinc 6.3; mercury 1.3 million dollars. Here we have 
 the big seven of old, with the exception of tin, replaced by the 
 modern zinc. 
 
 9. These seven old metals are easily DISTINGUISHED. 
 Mercury is a heavy liquid, silvery white. Tin and lead are 
 readily fusible; color and gravity distinguish them: Sn, 
 white, 7.2; lead, bluish-gray, 11.4. The three most lustrous 
 and malleable metals melt in the blowpipe flame, and are dis- 
 tinguished by color and gravity: Cu, red, 8.8; Ag, white, 
 10.5; Au, yellow, 19.4. Iron is infusible in the blowpipe 
 flame, grayish- white, and has G 7.8; it is also magnetic. 
 
 10. Zinc (Zn) was known to ALCHEMISTS in the 15th cen- 
 tury; it is a metal, but malleable only at a moderate range 
 of temperature (100 to 130 degrees); melts at 415, G 6.9; 
 boils 940. The readily fusible and quite volatile metals Ar- 
 senic (As), Antimony, (Stibium, Sb) and Bismuth (Bi) are 
 so brittle that they can be pulverized; color and gravity will 
 distinguish them : As, corroding black, 5.7 ; Sb, is white, 6.7 ; 
 Bi, reddish-white, 9.8. Probably at some temperature these 
 will show malleability. 
 
 11. DURING LAST CENTURY the very heavy (21.5) white 
 metal Platinum (Pt), infusible in the blowpipe flame, was 
 found in Brazil. The lighter (11.4) companion Palladium 
 (Pd) was distinguished by Wollaston, 1803. Nickel (Ni) and 
 Cobalt (Co) are rare companions of iron, equally infusible in 
 the blowpipe flame, almost equally magnetic, but heavier 
 (8.8) and whiter; Ni corrodes green, Co pinkish-red. Manga- 
 nese (Mn) and chromium (Cr) also resemble iron, but are not 
 yet used as metals. 
 
 12. Near the beginning of the present century a number of 
 LIGHT METALS (G less than 5) were discovered; the follow- 
 
98 
 
 LECTURE 6. 
 
 ing have lately come into use. Aluminium (Al) quite white, 
 like silver, has F 625, G 2.56, and does not corrode in dry 
 air. Magnesium (Mg), grayish -white, F 420, G 1.75; burns 
 most brilliantly to a white ash when lit by a match. Finally 
 the silver white metals sodium (Natrium, Na) and potassium 
 (Kalium, Ka) cannot be kept in air, are lighter than water, in 
 contact with which they burn. 
 
 Notes 3. — The great Iowa Meteor (10:20 P. M., February 12, 1875) 
 was seen throughout the territory extending from St. Louis to St. Paul 
 and from Chicago to Omaha. Its explosion was heard over the ten 
 thousand square miles of Iowa shaded on the map, p. 44. 
 
 The meteorites fell in Iowa County, Iowa, scattered over an elliptic 
 area extending nearly ten miles from southeast to northwest, and almost 
 three miles across at the widest. The greatest stones (all containing 
 over ten per cent of native nickelliferous iron in granular form) fell 
 between the seven towns of the Amana Colony; hence the name Amana 
 Meteorites. I made seven collections, aggregating over five hundred 
 pounds; four of these groups are well shown on page 45 of the Atlas. 
 The two largest (Nos. 22 and 33) were not my own property, but en- 
 trusted to me for study and protection. The largest stone weighs seven- 
 ty five lbs. (No. 33) ; the smallest two oz. (No. 32). 
 
 The following specimens, arranged in decreasing order of weight, 
 were presented by the author to the principal mineralogical museums of 
 Europe: No. i, Paris (5 kilos, nearly); 2, London; ii, St. Petersburg; 
 4, Vienna; 13, Brussels; 5, Copenhagen; 14, Harlem; 6, Berlin; 15, 
 Paris (second specimen, over 2 kilos) ; 7, Christiania; 8, Stockholm ; 16, 
 Munich; and No. 9, Lausanne (i kilo). 
 
 The specific gravity ranged from 3.45 to 3.50. 
 
 Meteorites, entering our atmosphere from space beyond, are the 
 only cosmical substances accessible to the chemist; hence their extra- 
 ordinary importance. They range from pure nickelliferous irons to 
 STONES almost destitute of metallic iron. 
 
 The oldest collection of meteorites is at Vienna. It was mainly de- 
 veloped by Haidinger (p. 28), and is now again rapidly growing under 
 Br^zina. It contains 500 distinct localities, of which 320 are stones; the 
 total weight is three tons and a half. The collection of meteorites at the 
 Museum of the Jardin des Plantes at Paris was greatly developed under 
 the care of the eminent Daubree, and is now in charge of Meunier. The 
 grand collection of the British Museum at London is in charge of 
 Fletcher. The London collection is the richest, because of the vast ex- 
 
METALS, OLD AND NEW. 
 
 1)9 
 
 tent of the empire in which the sun never sets, and because English 
 intelligence is ever ready to part with British gold to secure prime ma- 
 terials for science. Thus they possess the largest meteoric iron from 
 Cranbourne, Australia, weighing ten tons; and their gold secured the 
 most remarkable Estherville meteorite (May lo, 1879) from this land of 
 millionaires. However, this meteorite was drawn up from its wet hiding 
 place for my study, before it left this country. 
 
 7. CALCINATION AND REDUCTION. 
 
 1. GOLD heated on charcoal, in the fusing point of the 
 blowpipe flame, will promptly melt to a metallic globule, but 
 suffer no other change. When cold, it retains the globular 
 form, has all its original properties, and lost nothing in weight. 
 It has been TRIED BY FIRE. (1 Pet. 1.7; Rev. 3, 18). It 
 remains the king of metals; a metallic globule obtained by the 
 blowpipe is still called a regulus, and pure metals are called 
 reguline, as of old. 
 
 2. Silver melts like gold, but loses slightly in weight; a 
 small amount of a metallic calx is deposited as a reddish IN- 
 CRUSTATION on the charcoal. Heat this incrustation for an 
 instant with a good, steady, inner flame, and minute, brilliant 
 white silver globules will appear. The calx has been reduced 
 again to reguline silver. Mercury completely volatilizes in 
 the blowpipe flame. 
 
 3. Copper melts like gold and silver. The globule re- 
 mains red in the inner flame, tinging that flame green, while 
 in the outer flame the globule turns black on the surface. 
 This copper ash, scraped off, gives reguline copper in the 
 inner flame. 
 
 Most other metals are much more readily CALCINED, and 
 correspondingly more difficultly REDUCED. 
 
 4. Exposing a fragment of LEAD on charcoal to the blow- 
 pipe flame, it melts almost instantly, boils, and burns with a 
 bluish flame to a calx or ash (Litharge) which forms quite a 
 
100 
 
 LECTURE 7. 
 
 large yellowish, incrustation on the charcoal. If the outer 
 flame is used for some time, the incrustation will be reddish 
 (red lead), and all metallic lead will be calcined. 
 
 5. This lead incrustation, heated in the inner flame, almost 
 instantly yields a multitude of minute globules of metallic lead 
 (reguli), readily recognized as such by color, softness and 
 malleability. 
 
 Thus lead is readily calcined in the outer, and reduced in the 
 inner flame. This change from metal to calx, and reduction 
 from calx to regulus, may be repeated any number of times. 
 
 6. Lead containing some silver will leave that silver as a 
 pure regulus, while the lead is calcinated in the outer blowpipe 
 flame. In this manner much of the silver has been extracted 
 from argentiferous lead from time immemorial ; the process is 
 called CUPELLATION. The name litharge (lith-argyros, 
 silver stone) still in use points to the antiquity of this process. 
 On a porous support (bone ash cupel) it works better than on 
 charcoal, the melted calx soaking into the cupel. 
 
 7. TIN heated on charcoal in the outer flame melts and 
 forms a white incrustation due to its calcination. This in- 
 crustation can be reduced to a regulus, especially after mixing 
 the calx with a little soda and borax. Aiding reduction to the 
 metallic state, soda alone or with borax, is spoken of as a 
 REDUCING FLUX. 
 
 8. A fragment of ZINC is so promptly calcinated in the 
 outer flame that its fusion is usually not noticed. It burns 
 with a brilliant green flame and deposits a large incrustation 
 which (as well as the RESIDUE of calx left where the metal 
 was) is infusible, yellow while hot, and turns white on 
 cooling. This change in color can be indefinitely renewed by 
 repeated heating. 
 
 9. MAGNESIUM burns with extreme brilliancy, leaving a 
 pure white, infusible residue of calx. ALUMINIUM burns also, 
 but much less readily; its calx is also white and infusible. 
 
CALCINATION AND REDUCTION. 
 
 101 
 
 These white infusible masses cannot be reduced by the 
 blowpipe, but are readily distinguished by igniting them after 
 the addition of a drop of COBALT SOLUTION. The calx from 
 aluminium will become deep blue, that from magnesium pale 
 rose, while zinc calx treated in this way becomes green. 
 
 10. The metals As, Sb, Bi burn readily and leave an ash. 
 The most volatile ARSENIC, emitting the odor of garlic, dis- 
 appears, leaving but a slight white incrustation far away from 
 the sample. ANTIMONY melts to a globule and burns with 
 a white smoke, rising straight up from the sample when the 
 flame is withdrawn ; when the burning globule is dropped on 
 the table, it breaks into many small globules, each leaving a 
 white trail of the calx. BISMUTH gives a yellow incrustation. 
 When reduced, both antimony and bismuth are brittle, dis- 
 tinguishing them from tin and lead. 
 
 11. IRON heated in the outer flame gives a black residue, 
 no incrustation; when again exposed to the inner flame (best 
 with soda) only gray, MAGNETIC grains or spangles are ob- 
 tained. COBALT and NICKEL act in a like manner. 
 
 They are however readily distinguished by fusing a little 
 of the calx into a borax bead. Iron will make the bead 
 yellowish in the outer, colorless in the inner flame; nickel 
 gives a brownish bead, and with cobalt the bead shows a 
 splendid deep blue color. The chromium beads are green, 
 those containing manganese are amethyst in the outer, colorless 
 in the inner flame. 
 
 12. The light metals SODIUM and POTASSIUM should not 
 be burnt in the blowpipe flame; it would be very dangerous. 
 They leave white, fusible residues, coloring the flame yellow 
 (Na) or purple (Ka). 
 
 Thus all metals may be readily distinguished in a few in- 
 stants by the blowpipe, even if they are calcinated or otherwise 
 combined. These fire-tests or PYROGNOSTIC CHARACTERS 
 of the metals, should be familiar to all who wish to study 
 chemistry. They are the most ready and distinct means for 
 the recognition of the metals under all conditions. 
 
8. ALLOYS AND AMALGAMS. 
 
 1. The different metals can be melted together in various 
 proportions forming ALLOYS, several of which have been in 
 common use from time immemorial, such as bronze and brass. 
 If one of the metals is mercury, the alloy is called an AMALGAM. 
 
 2. The readily fusible white metals are very soluble in 
 mercury. Lead, antimony, bismuth and even silver, dissolve 
 so readily and abundantly in mercury as to cool the mass, over 
 20 degrees (down to 16 below zero) . The tin amalgam is used 
 as a coating on glass for mirrors. 
 
 Iron is insoluble in mercury; so are the other metals 
 infusible before the blowpipe, like platinum. Accordingly, 
 mercury is shipped in iron flasks, each holding 35 kilos. 
 
 3. Gold is about as soluble in mercury as silver. The 
 GOLD AMALGAM is solid at common temperatures, and can be 
 separated by wringing out the chamois into which the mercury 
 and amalgam has been poured; the mercury will run through, 
 the solid amalgam remaining. The amalgam loses about one 
 third of its weight on heating, or contains two parts of gold to 
 one of mercury. 
 
 4. The bulk of all the mercury produced (about 4000 tons 
 a year) is used for the EXTRACTION of GOLD and SILVER. 
 Gold sand is concentrated by washing, the lighter materials 
 being removed farthest. When sufficiently concentrated, the 
 remaining heavy material is treated with mercury, which dis- 
 solves the gold. The excess of mercury is separated as above 
 from the gold alloy, which then by heat is freed from the 
 mercury. 
 
 5. SOLDER, for tin ware, is an alloy of equal parts of tin 
 and lead, melted together in an iron ladle. It melts at about 
 190 degrees, which is 40 degrees below the fusing point of tin, 
 the most fusible of the two ingredients. In general, the alloys 
 are more fusible than their constituents. 
 
ALLOYS AND AMALGAMS. 
 
 103 
 
 6. The most important of all alloys in the history of man- 
 kind is BRONZE, containing about one part of tin to nine of 
 copper. In ancient days it was smelted direct from a mixture 
 of copper and tin ores, or by adding tin ore to melted copper. 
 By slow cooling it hardens, by sudden cooling it becomes mal- 
 leable (contrast with steel). 
 
 7. The ancients, from the Egyptians to the Romans, made 
 WEAPONS, TOOLS and ORNAMENTS of bronze. Until 
 recently, canons were made of bronze ; now it is used for 
 statuary, bells, medals and ornamental work. The copper is 
 first melted, then the tin added in reasonable excess, to allow 
 for loss by combustion. 
 
 8. BRASS (yellow) is an alloy of two parts of copper with 
 one of zinc. It can be cast, hammered, rolled and drawn and 
 thus is most readily shaped into any form. It was used before 
 zinc was known, by adding the mineral cadmia (a zinc ore) to 
 molten copper. By adding an amount of nickel equal to that 
 of zinc to the brass, German silver results. 
 
 9. TYPE METAL consists of lead about 4 and antimony 
 1 part, with some tin. It is very readily fusible, and expands 
 upon solidification (as does water on freezing), thus filling the 
 form exactly to the minutest detail. 
 
 Very fusible alloys contain bismuth. Thus Darcet’s Metal, 
 melting in the steam over boiling water, consists of bismuth 8, 
 lead 5, tin 3 parts; it melts at 94 degrees. 
 
 10. The most characteristic modern alloy is ALUMINIUM 
 BRONZE (copper 9, aluminium 1 part), which is very light 
 and resembles gold in appearance. Ferroaluminium contains 
 9 iron to 1 aluminium; it is much stronger than the above. 
 
 11. Native gold generally contains some silver. Australian 
 gold averages 7 per cent., Californian gold averages 12 per cent, 
 of silver, and is light yellow. VVith about 20 per cent, it is 
 called Electron, the ASEM of the ancient Egyptians. From 
 this, pure gold or pure silver was obtained at will. The 
 
104 
 
 LECTURE 9. 
 
 alloys seemed to show that metals were variable and thus 
 gave some encouragement to the alchemists. 
 
 12. When the Egyptians had learned to separate silver 
 from gold, they dropped Asem from their list of metals. Their 
 method of separation, described in the Leyden papyri, is 
 essentially the same dry way process used till the present. 
 The active agents were calcined green vitriol and salt, as in 
 the ROYAL CEMENT of the alchemists. 
 
 9. ORES AND CLEAVAGE. 
 
 1. ORES ARE MINERALS FROM WHICH METALS CAN BE 
 PROFITABLY OBTAINED. Every student in chemistry should 
 know at least the principal ores from which already the 
 ancients and the alchemists extracted the metals; he should 
 be able to recognize them at sight and by handling them. To 
 
 .help him do so is the object of this lesson. 
 
 2. Ores are generally distinguished from other minerals by 
 a HIGH GRAVITY (4 and over) associated with LOW HARD- 
 NESS. Very few have a 
 hardness equal to glass (de- 
 gree 5) , that is, able to scratch 
 glass and be equally scratched 
 by it. Many have the hard- 
 ness of copper (3) only. 
 METALLIC LUSTER is fre- 
 quent; in that case, the color 
 is constant and therefore 
 specific. If the luster is not 
 metallic, the color is gen- 
 erally variable. 
 
 3. THE BLOWPIPE will promptly reveal the presence and 
 nature of the metal in the ore. It will also show whether the 
 ore is a sulphide or not; the former emit the odor of burning 
 
 AGRICOLA. 
 
ORES AND CLEAVAGE. 
 
 105 
 
 sulphur while heated. This test may be made by simply 
 heating the mineral in an open glass tube, held slanting in 
 the Bunsen flame. Some sulphides also yield a sublimate of 
 white arsenic and give the odor of garlic. 
 
 4. Accordingly, the ORES are readily DISTINGUISHED as 
 sulphides and free from sulphur. The last are either native 
 metals or calxes. The first are either simple sulphides or con- 
 tain arsenic also. We will give the principal distinctive prop- 
 erties for each of the common ores. 
 
 5. NATIVE METALS are distinguished by their luster and 
 malleability (flattening under the blow of a hammer) . They 
 give no odor of either sulphur or arsenic before the blowpipe. 
 Gravity and color distinguish them one from the other. G 17 
 to 19: Au, yellow; Pt, white; 11, Pd, white; 10, Ag, 
 white; Bi, reddish gray and rather brittle; 8.5, Cu, red; 8, 
 Fe, white, only in meteorites. 
 
 6. The CALXES are without metallic luster, either dull or 
 sub-metallic. HARD enough to scratch glass (over 5) readily, 
 are: G 6, CASSITERITE, brown, and brownish streak (streak 
 is the color of the powder, or trace on rough porcelain), con- 
 tains Sn; G 5, contain Fe; streak: Black, MAGNETITE; red, 
 HEMATITE. 
 
 7. Calxes not hard enough to scratch glass, but 
 scratching copper readily, are quite numerous, and have all a 
 specific gravity of about 4. Hence they are to be distinguished 
 by color (first named) and streak (second) : red, orange, 
 LlMONlTE (Fe) ; red, brownish-red, CUPRITE (Cu) ; reddish, 
 orange, ZINCITE (Zn) ; grayish, white, SMITHSONITE (Zn) ; 
 brownish, gray, SlDERlTE (Fe); green, green, MALACHITE 
 (Cu). GARNIERITE, the modern nickel ore, is green and 
 harder than Malachite; blackish-gray, black, PYROLUSITE 
 (Mn). 
 
 8. SULPHIDES HARD enough to scratch glass readily, but 
 resisting the knife, have all marked metallic luster and there- 
 fore are easily distinguished by their color. Yellow, PYRITE 
 
106 
 
 LECTURE 9. 
 
 (Fe, no As). The following contain arsenic and are distin- 
 guished by their color and gravity: Gray, (6) ARSENO- 
 PYRITE; white (8), LEUCOPYRITE, and red (7.5) NlCCO- 
 LITE (copper nickel, the old nickel ore). 
 
 9. SULPHIDES, NOT HARD enough to scratch glass, readily 
 
 yielding to the knife edge, have either brilliant metallic luster 
 or not. By their gravity and color they are readily distin- 
 guished as follows; the metal they yield before the blowpipe 
 being added. Brilliant metallic luster; gravity : 7.5, GALE- 
 
 NITE, gray, Pb; 5, TETRAHEDRITE, gray, much As, some 
 Ag; 4.5 STIBNITE, blackish -gray, Sb; 4, CHALCOPYRITE 
 (copper pyrite), brass-yellow, Cu. Without metallic luster; 
 gravity: 9, CINNABAR, red, Hg; 4, SPHALERITE, blackish 
 to yellow, Zn; 3.5 ORPIMENT, yellow. As; 3, REALGAR, 
 red. As. GRAPHITE (C) and SULPHUR (S) are readily dis- 
 tinguished from sulphides. 
 
 10. Almost every specimen of galenite shows many plane, 
 brilliantly reflecting surfaces. If struck by a hammer, it will 
 break according to such plane surfaces only, with extreme 
 readiness; we say it has perfect CLEAVAGE. There will be 
 seen three such cleavage planes, mutually under a right angle. 
 This is most characteristic of gale’nite. Magnetite shows four 
 cleavage planes; fine specimens of Sphalerite even six. Orpi- 
 ment has one cleavage only, according to which it will split 
 into thin foli«. Pyrite is entirely destitute of cleavage. 
 
 11. Choice specimens, taken from the walls of some cavity, 
 where the substances were free to grow, show beautiful 
 geometrical forms, all bounded by plane surfaces only. Such 
 specimens are CRYSTALS. Galenite, corresponding to its 
 cleavages, shows cubes, often with the corners equally cut off 
 (truncated) ; p. 66, fig. 2. Magnetite and Cuprite show 
 octahedrae; p. 58, 59. Tetrahedrite shows modifications of 
 half-octahedrae, or tetrahedrse ; p. 66, figs. 16, 9. ITematite, 
 especially from Elba, shows splendid six and twelve sided 
 forms (Elba Roses), p. 57. 
 
ORES AND CLEAVAGE. 
 
 107 
 
 12. Pyrite quite frequently is crystallized. Its simplest 
 and most common form is the cube, bounded by six equal 
 squares (p. 66, fig. 1). Upon inspection these squares are 
 usually found to be striated parallel to one side. Examining 
 the three squares meeting at one corner, these striations will 
 be found parallel to the three edges meeting at that corner, 
 (p. 54, figs. 17 to 19). In many cases the edges are beveled, 
 and finally show the so-called Pyritohedron (p. 66, fig. 21) 
 bounded by twelve five sided faces. 
 
 Note. The portrait of Georg Agricola has been inserted in the 
 text of this lecture. Agricola was called the father of mineralogy by 
 Werner, a century ago. He was born March 24, 1494 at Glauchau, 
 Saxony, and died in November, 1555, at Chemnitz, Saxony. He settled 
 in the new mining town Joachimsthal, Bohemia, and studied everything 
 pertaining to the rich silver veins which made that town and region 
 flourish. His works on metals and mining are the first which have 
 appeared during modern times; they are noted for thoroughness and 
 accuracy. The portrait is a copy of Schrauf’s, (Vienna 1894) which is a 
 reduction from Sambucus, Antwerp, 1574, plate 38. 
 
 10. CRYSTAL GEMS. 
 
 1. The old egyptian list of metals contains blue (chesteb) 
 and green (mafek) gems immediately after Gold (nub), Asem 
 and Silver (hat), and followed by bronze (chomt), iron (men) 
 and lead (taht). The Egyptians were familiar with the fact 
 that copper tints fluxes blue and green; but they distin- 
 guished the genuine gems easily from the artificial by their 
 hardness. Moses also was familiar with true gems. (Exod. 
 28). — Gems are sold by the CARAT which is one-fifth of a 
 gramme. 
 
 2. THE TRUE GEMS (p. 46) are crystals. of exceeding 
 hardness. To be prized as jewels they must also be trans- 
 parent and either absolutely colorless or finely colored. 
 Hence, good instructive specimens are obtainable for study 
 
108 
 
 LECTURE 10. 
 
 at reasonable rates, while the price of the same materials 
 fit for the lapidary may be beyond reach. Gems do not differ 
 much in specific gravity; accordingly, this property is of little 
 value in distinguishing them. 
 
 3. The gem crystals are generally well formed, and their 
 DEGREE of SYMMETRY may be recognized without much dif- 
 ficulty. If the same face, as to inclination and position 
 towards the direction of a more or less marked corner or prism, 
 occurs twice only, the crystal is called rhombic, (pp. 61, 62) ; 
 if thrice, rhombohedral, p. 57; if four times, quadratic, (p. 60), 
 and if six times, hexagonal, (Beryl, p. 56). If the same 
 crystal, held in two different positions, shows both rhombohe- 
 dral and quadratic symmetry, it is called tesseral (pp. 58, 59). 
 (For mono-and tri-clinic, see note). 
 
 4. The degree of HARDNESS of quartz is called 7 ; that of 
 topaz 8, of corundum 9 and of the diamond 10. The most 
 precious gems possess the hardness 8 and over; namely topaz 
 8, spinel 8, chrysoberyl 8i, ruby and sapphire 9, diamond 10. 
 Below these we have the emerald 7f, zircon 7j, turmaline 7i 
 and the “poor man’s gems” garnet and quartz 7. 
 
 5. These gems are also CHEMICALLY divisible into the 
 same two groups. All of lower hardness, including topaz, fail 
 to dissolve in a bead of microcosmic salt in the blowpipe flame, 
 precisely as do glass and other silicates ; to that extent they 
 are natural glasses, crystalized. But the harder gems, spinel, 
 chrysoberyl and corundum (sapphire and ruby) do dissolve, 
 and are not glass-like (silicates). 
 
 The diamond stands, entirely by itself; it is combustible 
 under special conditions. 
 
 6. Quartz crystals (p. 65) are quite abundant, and very 
 often perfectly transparent (rock crystal) ; if purple, amethyst, 
 if dark wine yellow, smoky quartz. Its hardness is taken as 
 the standard 7. Gravity 2.7 ; no cleavage. Symmetry 
 rhombohedral; commonly a regular six-sided prism, r, striated 
 crosswise (Figs. 6, 7) dominates, terminated by the three 
 
CRYSTAL GEMS. 
 
 lOJ) 
 
 rhombohedral faces, P, usually alternating with a second 
 smaller set of rhombohedral faces, Z. A little experience will 
 enable any one to recognize the constancy of crystal form in 
 the apparently infinite variety of appearances and linear 
 dimensions. 
 
 7. The GARNET (p. 59) is recognized by its form, being 
 generally a dodecahedron (bounded by twelve equal rhombs, 
 d), inclined under a right angle over the long diagonal, and 
 forming a rhombohedron of 120 degrees at the three sided 
 corners. Garnets show many colors; the pyrope, used in 
 jewelry, is deep red. 
 
 TURMALINE crystals have a dominant prism, striated 
 lengthwise, surmounted by rhombohedral faces; usually only 
 one termination shows, the crystals breaking readily cross- 
 wise. Colors varied, often in belts or zones. 
 
 8. The Zircon (p. 60) is noted for quadratic symmetry 
 only; fine transparent brownish and orange crystals are used 
 under the name of hyacinth. 
 
 BERYLS (p. 56) are quite common and very large, forming 
 regular six-sided prisms, terminating in a base at right angles 
 thereto, and show cleavage after this plane. Fine beryls are 
 always small and prized as AQUAMARINES when blueish ; 
 when bright green, they are the most valuable EMERALD. 
 
 9. The TOPAZ (pp. 61, 62; also p. 67, Fig. 43) forms a 
 rhombic prism (M, 1), striated lengthwise, and possessing 
 perfect cleavage crosswise (i. e. basal, P) ; the crystals show 
 generally only one termination, the basal plane with the domes 
 f and y and the pyramid i. Yellowish colors are most common. 
 The shade of color and especially the character or habitus of 
 the crystals are peculiar to each principal locality, so that the 
 expert can tell from the habitus and color whether the topaz 
 came from Brazil, Saxony, Siberia or Japan. 
 
 10. SPINEL is tesseral, the octahedron (bounded by eight 
 equal equilateral triangles, p. 58, fig. 1) dominating. CHRY- 
 SOBERYL (p. 62, Alexandrite) is rhombic; but its prism (119.8 
 
110 
 
 LECTURE 10. 
 
 degs.) is so nearly hexagonal (120 degs.) that it gener- 
 ally occurs in six-sided stellar combinations. A Russian vari- 
 ety, known as ALEXANDRITE, is emerald green in reflected, 
 deep red in transmitted light, thus showing the Russian colors. 
 Transparent specimens thereof form very valuable gems. 
 Atlas, p. 53. 
 
 11. CORUNDUM (p. 56) is exceeded in hardness by the 
 diamond only, so that it readily, is distinguished from all 
 other bodies. It crystallizes in rhombohedral forms, usually 
 showing a double pyramid, terminated by a base, o. It shows 
 perfect cleavage according to its base and a rhombohedron, R. 
 Transparent crystals of corundum are next to the diamond in 
 value; when blue they are called SAPPHIRE, when red RUBY. 
 Good rubies have been made by Fremy. Impure corundum, 
 containing hematite, is called emery, and used for grinding 
 and polishing steel. 
 
 12. The DIAMOND is the hardest of all bodies; it crystal- 
 lizes in octahedrae (p. 66, fig. 9) variously modified (figs. 11, 
 12), and has four cleavage planes parallel to the faces of the 
 octahedron. Imperfect diamonds, unfit for jewelry, are called 
 bort. Black pebbles of diamond hardness are called carbonado 
 and used for rock drills. The price of good diamonds increases 
 approximately as the square of the number of carats. Dia- 
 monds have been made by Moissan (p. 36). 
 
 Notes — 2. The cost of gems varies greatly according to quality. 
 The following extract from the price list of a New York dealer is for 
 ^^fair to good gems, neither poor nor the best.” The price is given in 
 dollars per carat; the order is that of our description. 
 
 Quartz: rock crystal 3-1; amethyst 'ii,— i ; garnet ^-2 ; turmaline 
 2-12; zircon 2-8; beryl, golden and aquamarines 1-8; emerald 10-80; 
 topaz i-5 ; spinel 8-48; chrysoberyl 3-16; alexandrite 24-96. Corundum : 
 sapphire 3-24 ; ruby 8-96. Diamond 50-150. 
 
 3. The important subject of Crystal Symmetry can only be ap- 
 proached by the beginner when aided by a good atlas of crystal forms. 
 For that reason 18 plates of the admirable atlas of Nikolai von Kokscha- 
 
CRYSTAL GEMS. 
 
 Ill 
 
 row^ accompanying his great work: Materialien zur Mineralogie Russ- 
 lands, have been added in good photo reductions. In most cases each 
 form is represented first in perspective and' right helow in horizontal 
 projection; the first is marked bv the number, the second by the same 
 number and the word bis ” (twice, second). This second figure shows 
 the symmetry undisturbed by perspective, and should be specially studied. 
 Each face is generally designated by a letter. 
 
 In addition to the five degrees of symmetry specified, two lower forms 
 exist, namely: moxoclinic, having only symmetry right and left, in 
 pyroxene, p. 63 and orthoclase p. 64; and finally triclinic, having no 
 symmetry whatever, or being asj'mmetric, see Lepolith (really anorthite) 
 p. 64. 
 
 9. Good specimens of topaz for the study of rhombic crystal form are 
 comparitively cheap; the basal cleavage avoids the possibility of mistakes. 
 
 The three plates copied from Kokscharow show some of the finest 
 topaz crystals in their true form, each face exactly as it is developed. 
 The scale of our plates is almost one-half of the original; exactly 0.44 or 
 nine-twentieths. See pages 61, 62, where the plates are designated by 
 the letters a, d and f at the right hand top. 
 
 On page 61 (a and d) figures 58, 59 and 67 represent (half size) 
 splendid topaz crystals from Nertschinsk, Siberia ("Vol. Ill, p. 207). 
 They are transparent, dark wine yellow. The crystal fig. 59 weighs 1.6 
 kilograms. 
 
 On page 62 (f) is given (fig. 76) the horizontal projection (half natural 
 size) of the finest and largest topaz crystal yet obtained. It is 28 cm 
 high, 16 and 12 cm across, and weighs 10.2 kilograms. Von Kokscharow 
 (III 378) says: a topaz crystal of so extraordinary size and 
 
 beauty as has never been seen before. This crystal belongs to the greatest 
 rarities of the mineral kingdom, on account of its extraordinary magni- 
 tude, perfection of crystallization, fine color (dark wine yellow) and 
 transparency.” It was found in the Nertschinsk region, in the mountains 
 near the Urulga river, Transbaikalia, Siberia; was presented to Emperor 
 Alexander II in i860, and is deposited in the Mineralogical Museum of 
 the Mining Institute of St. Petersburg. 
 
 10. The group of Alexandrite crystals represented (p. 53) is one of 
 the most magnificent specimens of native crystals (v. Kokscharow, Vol. 
 IV, p. 62). The group contains 22 large and finely formed twin crystals; 
 the group is 25 cm long, 14 cm high and ii cm wide, and weighs over 5 
 kilograms. 
 
 The Gems. Page 46, shows the common crystal form of the following: 
 
 I, diamond; 2, sapphire; 3, ruby; 4, amethyst; 5, emerald; 6, garnet; 7, 
 aquamarine; 8, topaz; 9, peridot or olivine, chrysolite; 10, rock crystal; 
 
 II, turmaline. This plate is a half-tone reduction from the fine colored 
 plate V of Simonin, Les pierres, Paris, 1869. 
 
11. CRYSTAL STONES. 
 
 1. THE RECOGNITION OF ANY MATERIAL by means of 
 its physical properties is a habit that must be cultivated by 
 every one who would study chemistry successfully. Incident- 
 ally the student becomes practically acquainted with a number 
 of those minerals on which the chemist depends for his ma- 
 terials — and even for the very ideal of chemical individuality. 
 
 2. The following dozen STONES should be so familiar to 
 every student that he can recognize them promptly in any of 
 their varied forms. As a group they are not as hard as the 
 gems, nor as heavy as the ores. H 6 and G 4, are the limits. 
 The dozen selected are the most important practically, and the 
 best marked physically and crystallographically. Good speci- 
 mens can be had at comparatively little outlay; many can be 
 collected. 
 
 3. To recognize a substance, its properties should be 
 observed in a DEFINITE ORDER. First (by sight) luster, then 
 color and streak; next (by handling), hardness and by mere 
 lifting an estimate of the specific gravity is obtained. Then 
 the specimen — if not a crystal — should be broken by a blow; 
 that will reveal fracture or cleavage; in the latter case, the 
 number, relative position and degree. Finally, if crystal faces 
 visible, they should be examined with a view to determine 
 the symmetry of the crystal. In that case, cleavage planes 
 are often revealed by existing cracks. 
 
 4. The last five of the minerals selected are SILICATES, 
 that is, they leave an insoluble silica skeleton in the micro- 
 cosmic bead (10, 5); they are among the most common 
 constituents of the hard rocks, such as granites. The others 
 are not silicates. The first alone is soluble, its taste reveals 
 its nature, salt; the merest trifle of it tinges the blowpipe 
 flame persistantly and intensely yellow (Na). The next five 
 tinge the flame orange, appearing siskin -green through a green 
 glass; they contain calcium (Ca). The heaviest tinges the 
 flame yellowish green; it contains the metal barium (Ba). 
 
CRYSTAL STONES. 
 
 113 
 
 5. TABULAR 
 
 STONES— 
 
 VIEW 
 
 OF THE PROPERTIES 
 
 OF A DOZEN 
 
 No. 
 
 Name. 
 
 n. 
 
 G. 
 
 Cleavage. 
 
 Crystal Synimetrj’. 
 
 I. 
 
 Halite, 
 
 2 
 
 2.2 
 
 3 pfct., 90 degs. 
 
 Tesseral. 
 
 2. 
 
 Gypsum, 
 
 2 
 
 2-3 
 
 I em.,.2 pfct.. 
 
 Monoclinic. 
 
 3 * 
 
 Calcite, 
 
 3 
 
 2.6 
 
 3 perfect, 105 degs. 
 
 Rhombohedral. 
 
 4 - 
 
 Aragonite, 
 
 3 h 
 
 2.9 
 
 I imperfect. 
 
 Rhombic. 
 
 5 * 
 
 Fluorite, 
 
 4 
 
 3-1 
 
 4 perfect, octah. 
 
 Tesseral. 
 
 6. 
 
 Apatite, 
 
 5 
 
 3-1 
 
 I imperfect. 
 
 Hexagonal. 
 
 7 ' 
 
 Barite, 
 
 3 
 
 4-5 
 
 I pfct., 2 less so. 
 
 Rhombic. 
 
 S. 
 
 Mica. 
 
 2 
 
 2.9 
 
 I eminent. 
 
 Six-sided. 
 
 9 * 
 
 Amphibole, 
 
 
 3 -^ 
 
 2 pfct., nearly 120 degs. 
 
 Monoclinic. 
 
 lO. 
 
 Pyroxene, 
 
 
 3-3 
 
 2 pfct., nearly 90 degs. 
 
 Monoclinic. 
 
 II. 
 
 Feldspar, 
 
 6 
 
 2-5 
 
 2 pfct., nearly 90 degs. 
 
 Mono ortriclin. 
 
 12. 
 
 Quartz, 
 
 7 
 
 2.7 
 
 no cleavage. 
 
 Rhombohedral. 
 
 6. All of these stones are destitute of metallic LUSTER, 
 that property being peculiar to metals and ores. The luster 
 is dull or vitreous according to the perfection of the specimen. 
 If ONE CLEAVAGE eminent, so perfect that it can be split 
 into thin leaves (Nos. 2,8) the luster will appear pearly, 
 which is noted even on the best cleavage of feldspar (No. 11.) 
 
 7. These minerals are generally colorless or white; but as 
 they have no metallic luster, their COLOR VARIES according 
 to impurities admixed, whether organic or inorganic. Thus 
 Halite (Rock Salt) and Fluorite (Fluorspar) show beautiful 
 colors: yellow, red, green, blue, mostly due to organic matter, 
 destroyed by ignition. Pyroxene (augite) and amphibole 
 (hornblende) are generally green to black, from iron silicates. 
 Quartz and calcite show also most of the colors of the rainbow. 
 
 8. Contact with the tongue reveals the only SOLUBLE 
 mineral in the list, HALITE. Hardness 2, indentable by the 
 finger nail, singles out gypsum and mica. Of these two, only 
 GYPSUM occurs massive and fibrous; when foliaceous, its 
 folia are flexible, but not elastic, while MICA always is folia- 
 ceous and elastic as well as flexible. [CRYOLITE from 
 Greenland, has greater gravity (3) and is insoluble in water; 
 otherwise it might be mistaken by hardness and cleavage for 
 poor specimens of rock salt. See p. 51.] 
 
114 
 
 LECTURE 11. 
 
 9. Copper hardness (3) gives the three species Calcite, 
 Barite and ARAGONITE (p. 67, fig. 55). This latter is very 
 rare, almost destitute of cleavage, while the other two possess 
 perfect cleavages. BARITE is readily distinguished by its high 
 gravity, which has given it the common name Heavy Spar. 
 By cleavage it yields right rhombic tablets of 101.7 degs. 
 The lighter is CALCITE or calcareous spar, the most common 
 of all minerals, which will receive special study further on. 
 It effervesces with vinegar. 
 
 10. FLUORITE (Fluorspar) and APATITE (p. 67, fig. 37) 
 are not scratched by copper. Fluorite generally shows its 
 cleavages readily, while apatite practically has no cleavage. 
 The four cleavages of Fluorite equally developed yield a tetra- 
 hedron (p. 66, fig. 16) ; splitting off the corners also, the 
 regular octahedron (fig. 9) results. Fluorspar crystallizes 
 beautifully (figs. 1, 5, 7, 14, etc.) and shows many fine colors; 
 it is the ERZBLUME (ore blossom) of the old miners, ac- 
 companying valuable ores. 
 
 11. The silicate stones are easily distinguished by hard- 
 ness and cleavage combined. One eminent cleavage, MICA 
 (isinglass) ; no cleavage, QUARTZ, if hardness 7 (good file). 
 Hardness below this, but the specimen scratching glass quite 
 readily, showing two cleavages under a right angle: FELD- 
 SPAR (p. 64: Orthoclase and Anorthite, here called Lepolith) 
 which is reddish or whiteish, except in the bright green 
 Amazone stone. AUGITE (Pyroxene, p. 63) and HORN- 
 BLENDE are not as hard, but heavier, blackish and greenish 
 colors prevailing; only if showing cleavage, can they be dis- 
 tinguished, except that fibrous varieties are hornblende. 
 
 12. Calcite (p. 65) exhibits a thousand modifications 
 (secondary forms) of its rhombohedron, P, of 105.1 degrees, 
 according to which all are broken up by the cleavage planes 
 parallel to the three faces of the rhombohedron meeting in one 
 corner (HAUY, p. 55). The most common secondary forms 
 are the Scalenohedra (r, figs. 15 to 21, Dogtooth Spar) ; next 
 thereto the hexagonal prism, c, and the obtuse rhombohedron. 
 
CRYSTAL STONES. 
 
 115 
 
 g (Nailhead Spar). Marble is crystalline (saccharine marble) ; 
 variegated marble may be massive. Limestone is the most 
 common form. The most perfectly transparent cleavage 
 pieces come from Iceland (Iceland Spar) ; next in perfection 
 are the spars from Lampasas, Texas. 
 
 12. ROCKS AND VEINS. 
 
 1. Limestone generally is stratified, forming banks or 
 strata of varying thickness, apparently deposited in a primeval 
 sea. The strata have since, in many places, been tilted and 
 broken. Extensive deposits of limestone occur, hundreds of 
 feet in thickness, and for hundreds of miles in extent. They 
 furnish locally fine building stone and material for burning 
 lime. 
 
 2. Many LIMESTONES are quite hard, some even crystal- 
 line; but ah effervesce readily with vinegar. The beautiful 
 white MARBLE of Carrara has been quarried for statuary and 
 ornamental work since the days of the Romans, (p. 51). The 
 Greeks obtained a superior, more fine grained marble for their 
 statuary and monumental buildings from the island of Paros. 
 Gypsum also forms valuable rock deposits; easily dis- 
 tinguished by yielding to the finger nail and not effervescing 
 with vinegar. 
 
 3. SANDSTONES consist of grains of sand (irregular frag- 
 ments of quartz) held together by some stony cement, often 
 calcareous and effervescing with vinegar. These stones are 
 also stratified, but less extended than the limestones; they 
 vary exceedingly in their characters, as to color, grain and 
 durability of the cement. Many localities offer excellent 
 building stones (Strasburg Munster). The building stones 
 quarried in the United States during 1895 had a value of 35 
 million dollars. 
 
 4. CLAY like deposits form extended strata, differing in 
 consistency from moist, plastic clays to shales and slates (for 
 
116 
 
 LECTURE 12. 
 
 roofing). When heated to redness, clays lose their water, 
 shrink and become hard (brick, pottery.) In a bright white- 
 heat most ordinary clays will show signs of fusion ; the purest 
 clays (white, free from iron, lime, etc.) resist furnace heat, are 
 called fire clay, and serve for crucibles, finer pottery, to porce- 
 lain. All these clay rocks contain aluminium for they will 
 (after removing iron, etc.) give the blue cobalt reaction (7.9). 
 
 5. These common stratified rocks — limestones, sandstones 
 and shales — are resting upon and at times tilted up by the 
 the two principal crystalline siliceous rocks, the graystones 
 (granites) and the GREENSTONES (hornblendic and basaltic 
 rocks). In granite the three constituent minerals (mica, 
 feldspar and quartz) may be distinguished without much diffi- 
 culty. The greenstones are heavier, containing more iron. 
 
 6. During great convulsions, the rocks, whether stratified 
 or not, have been cracked, deep fissures running nearly paral- 
 lel have been made. In the course of time, nature has healed 
 these wounds, filled up these crevasses in various ways, by 
 materials drawn from the adjacent rocks (the country) or from 
 the depths. Such filled up deep crevasses are called veins 
 (p. 47), especially if they contain ores with the other minerals 
 or veinstones (gangue). 
 
 7. The true veins extend indefinitely downwards; their 
 direction on the ground is called their strike, their inclination, 
 dip. The most common veinstones are quartz, calcite, fluorite 
 and barite. These gangues, as well as the associated ores, 
 are often quite symmetrically distributed across the vein, that 
 is, if from the left the order of minerals be a, b, c, d, it will 
 be the same from the right side of vein. See p. 47. 
 
 8. If, after a set of. veins has formed, like convulsions take 
 place again, another set of cracks may result, leading to an- 
 other set of veins with other gangue and other ores, CROSS- 
 ING the first and older ones, which thereby may have been 
 greatly displaced. (See right side, p. 47). At Ehrenfried- 
 ersdorf, a set of silver veins run from north to south, while the 
 tin veins run from east to* west. 
 
ROCKS AND VEINS. 
 
 117 
 
 9. The discovery of rich veins in a new country is a matter 
 of luck. The crowd drawn by the story makes a careful and 
 extended search (prospecting) and is followed by the general 
 settler. In a few years, the treasure found, has added a rich 
 and populous state to civilization. The words California, 
 Colorado, Australia, Transvaal, all tell the same story. In 
 Antiquity, similar effects of mining are recorded. 
 
 10. One of the most remarkable stratified rocks is stone 
 coal, H 2, G 1.5 and less, black combustible (p. 48). Anthra- 
 cite (hard coal) gives no volatile matter (bitumen) when 
 heated in a tube; the other coals give up to 50 per cent, 
 bitumen, and burn with a luminous flame. Asphaltum and 
 Petroleum are essentially natural bitumens, with but little 
 fixed carbon. Stone coal supplies our industries with heat 
 and power; largely replacing the slave labor of earlier civiliza- 
 tions. The United States produced 265 million dollars worth 
 of mineral combustibles in 1895 — as much as their total pro- 
 duction of metals. 
 
 11. Iron ores also occur as rock deposits. The magnetite 
 (p. 52) and hematite deposits of Elba formed the center of 
 metallurgy of Antiquity. We have' corresponding deposits in 
 Missouri (Iron Mountain, Pilot Knob) and especially on Lake 
 Superior (Marquette Region). In parts of England, iron ore, 
 coal and flux occur in neighboring strata, greatly favoring the 
 smelting of the iron. 
 
 12. Salt is obtained by the evaporation of sea water 
 (France, p. 50, top) ; from salt springs (Michigan, New York) ; 
 and above all as rock-salt. The Stassfurth rock-salt deposit 
 is over three thousand feet thick. That at Vilisca — over one 
 thousand feet thick— has been mined for centuries. At Cor- 
 donna, Spain (p. 50), rock-salt is q.uarried from a deposit 
 reaching over five hundred feet above ground. These deposits 
 are aijsociated with gypsum and other salts of sea water, 
 proving them to be the result of evaporation of bays of a 
 primeval ocean, or inland lakes (Dead Sea, Great Salt Lake). 
 
13. SALTS AND SPIRITS. 
 
 1. The ancients distinguished a number of substances re- 
 sembling rock-salt in appearance, solubility, and marked by 
 some peculiar taste ; the term SALT has been used to designate 
 all materials of this kind. The most important salts have 
 been in use for two thousand years ; surely, every student of 
 chemistry should be able to recognize them. 
 
 2. Already the Hebrews used two very soluble salts effer- 
 vescing with vinegar. Neter (to effervesce) was found in 
 lakes of northern Africa, and is permanent in air; we call it 
 SODA. The other, borith, was obtained by lixiviating wood 
 ashes; it is our very deliquescent POTASH. Both of these 
 substances are non volatile or fixed. A very volatile salt of 
 this kind (spiritus urinse) was at an early day obtained from 
 putrid urine; we call it Ammonium Carbonate, and obtain it 
 from stone coal (gas works refuse, tar water). 
 
 3. ALUM is a styptic salt. When heated in a tube it gives 
 off much water and leaves a light, white, ash -like residue, 
 called burnt alum. Accordingly, the ancients said alum con- 
 sists of water and earth. The old VITRIOLS (glass-like) are 
 similar salts, styptic, but heavier and yielding much less water; 
 the one is pale GREEN and gives iron before the blowpipe, 
 while the other is deep BLUE and yields copper.. Pyrites 
 weathering give green vitriol, while blue vitriol results from 
 the weathering of copper pyrites (9. 8). 
 
 4. Our nitre or SALTPETRE (sal petr«) was found as 
 crusts on rocks in caves of Asia Minor; it is distinguished 
 from the preceding salts by violently deflagrating on glowing 
 charcoal, showing its leading character of supporting combus- 
 tion. BORAX on the contrary, melts quietly to a colorless 
 drop or bead; it readily dissolves metallic ashes, forming 
 characteristic colors therewith. It is also a most useful flux 
 in smelting. 
 
SALTS AND SPIRITS. 
 
 119 
 
 5. Limestone when burnt leaves quick LIME, which heats 
 up greatly with water; yielding slacked lime which is slightly 
 soluble in water (Limewater) and very CAUSTIC (corrosive 
 to the skin and organic tissue). While limestones effervesce 
 with vinegar, slacked lime does not. Concentrated solutions 
 of the effervescent soluble salts (2) yield with slacked lime, 
 upon decantation, the most caustic liquids known, the CAUS- 
 TIC ALKALIES. 
 
 6. Sal ammoniac first came from Egypt in fibrous cakes., 
 already described by Dioscorides; the crude salt of to-day 
 has the same characteristic fibrous structure. When warmed 
 with slacked lime, pungent spirits of ammonia are abundantly 
 produced and readily taken up by water, giving our Aqua 
 Ammoniae, the volatile alkali. 
 
 7. The ancient chemists studied the properties of all ma- 
 terials at high temperatures. They distinguished the very 
 volatile substances as we do. The volatile principle collected 
 in a distilling apparatus they termed SPIRIT, independent of 
 the special property, which might be acid, like vinegar, neutral, 
 like water, or alkaline, like ammonia. Litmus turns red with 
 acids, blue with alkalies, and remains unchanged (blue or 
 red) with neutral substances. 
 
 8. VINEGAR (acetum) is the only acid known to the 
 ancients; it resulted from light wines exposed to air, turning 
 sour (vin aigre, french). We have used it to recognize lime- 
 stone, marble, soda, by the effervescence it produces. Vine- 
 gar dissolves lead, yielding SUGAR OF LEAD, readily soluble 
 in water. Such a solution gives an abundant white precipi- 
 tate with vitriol and alum solutions, even when much extra 
 vinegar has been added. None of the other salts show this 
 behaviour ( reaction ) . 
 
 9. Alum mixed with nitre and heated gives the strongly 
 acid SPIRITS OF NITRE, our nitric acid — the “first water” of 
 the alchemists. This corrosive liquid stains the skin and 
 wood yellow, and dissolves copper readily, while abundant and 
 
120 
 
 LECTURE 13. 
 
 » very noxious red fumes (rutilant vapors) pass off. Silver 
 also dissolves in this acid, leaving white transparent crystals — 
 lunar caustic, lapis infernalis — our SILVER NITRATE. 
 
 10. Alum and salt (murias) heated in the same manner 
 yield the less corrosive SPIRITS OF SALT, our muriatic acid. 
 It is easily distinguished from the preceding acids by giving a 
 white, curdy precipitate with silver nitrate; which precipitate 
 is readily dissolved by aqua ammonia. Accordingly, silver is 
 insoluble in muriatic acid. 
 
 11. Mixing both salt and nitre with alum, heat drives off 
 the most corrosive acid, AQUA REGIA, so called because it 
 dissolves even gold, the king of metals. These acids were 
 quite generally used by chemists in the days of Geber, more 
 than a thousand years ago. Aqua regia was called the “second 
 water” by the later alchemists. 
 
 12. Intensely heating alum (or any vitriol) alone (or with 
 dried, pure clay) we obtain SPIRITS OF VITRIOL, oui sulphuric 
 acid, or oil of vitriol. It chars most organic materials (wood), 
 and gives the same white precipitate with sugar of lead which 
 we‘ obtained with alum and vitriol solutions. 
 
 At present, the term spirit is restricted to the distillate from 
 wine and similar liquids; our alcohol is spirits of wine, spiritus 
 vini. 
 
 Notes. Section ii is in accordance with current information, accept- 
 ing the works of Geber as they exist in latin to be genuine, due to the 
 arab Djaber (eighth century). But Berthelot has published the original 
 text in arabic and finds (Comptes Rendus, T. ii6, p. 1 166-1171; 1S93) 
 that the latin works accepted for centuries as the translation thereof, are 
 works of European chemists of much later date; that the arabs did not 
 add to the chemistry of the Greek school. Consequently, that “ thous- 
 and years ago ” will have to be cut in two, leaving say half a thousand 
 years. 
 
14. SOLUTION AND CRYSTALLIZATION. 
 
 1. THE OCEAN is the greatest residual solution on the 
 globe. The taste of its water reveals the presence of common 
 and bitter salts. By evaporation sea-salt is obtained there- 
 from. The great (rock) salt deposits have undoubtedly been 
 formed in bays periodically in narrow communication with the 
 ocean (12, 12; Atlas, p. 50). Seawater contains 3j percent, 
 of salts, varying slightly in different regions. Forchhammer^ 
 1864. 
 
 2. SOLUTION is the conversion of a solid into a liquid by 
 means of a liquid. The liquid used is called the solvent, the 
 liquid resulting is called the solution. The word solution thus 
 is used both for the operation and the result. A solution is 
 saturated, when in contact (aided by repeated shaking) with 
 the finely pulverized solid, it does not take up any more 
 thereof. Concentrated is a solution approximating saturation; 
 dilute when remote from it. Water is the most common sol- 
 vent; alcohol, ether, and other volatile liquids are also used. 
 
 3. THE SOLUBILITY of a solid is the weight thereof dis- 
 solved to a saturated solution by a unit of weight of solvent 
 (Gay-Lussac, 1819). It may also be defined as the weight 
 of the solid contained in a unit of weight of the saturated so- 
 lution (Etard, 1894). For practical purposes, the STRENGTH 
 OF ANY SOLUTION (whether saturated or not) is usually 
 given by stating the weight of solid per unit of volume of the 
 solution; that is in milligrammes per cubic centimeter or 
 grammes per Liter. 
 
 4. THE SOLUBILITY INCREASES WITH THE TEMPERA- 
 TURE, as shown by the diagrams, p. 70. For alum, nitre 
 and blue vitriol dissolved in water, the increase is very rapid, 
 the Gay-Lussac curves rising steeply. Salt shows but a very 
 slight change in solubility. The Etard lines, p. 71, are 
 straight, or consist of several straight lines, the last section 
 
122 
 
 LECTURE 14. 
 
 (except for sulphates) running to the melting point. All 
 chemistry in the WET WAY is but an application of the facts 
 of solubility. 
 
 5. When a given solid is divided, the surface increases 
 rapidly, while the weight remains unchanged. As solution 
 can only take place at the surface of the solid in contact with 
 the solvent, it follows that PULVERIZATION must greatly 
 accelerate solution. Solids are first broken with hammer and 
 anvil, then crushed in a diamond mortar (steel socket with 
 steel pestle), and finally ground thoroughly fine in appropriate 
 mortars (porcelain, agate). 
 
 6. WARMING the finely pulverized solid with a reasonable 
 excess of solvent will effect rapid solution of all that is soluble. 
 Any insoluble impurities will remain in the solid state. They 
 can be removed by DECANTATION after the solution has been 
 standing undisturbed to permit the solids to settle; or better 
 and more rapidly, they are removed by FILTRATION through 
 a porous insoluble solid, usually filter paper, supported in a 
 funnel of 60 degrees aperture. 
 
 7. A hot, concentrated solution set aside will COOL slowly, 
 and generally soon show the growth of beautiful CRYSTALS, 
 the solubility diminishing as the temperature sinks. With an 
 almost boiling saturated solution of nitre, a half dozen con- 
 secutive crops of bulky masses of silky crystals may be ob- 
 tained by as many consecutive decantations, showing most 
 strikingly the enormous decrease of solubility of nitre upon 
 cooling. 
 
 8. While the gradual cooling of a hot, concentrated solu- 
 tion gives rapidly large groups of crystals, the most perfect 
 crystals are generally obtained from saturated solutions by 
 SPONTANEOUS EVAPORATION, in crystallizing basins and 
 dishes of glass or porcelain. On a small scale, watch glasses 
 answer admirably. For work with the magnifier and the 
 MICROSCOPE, a drop of solution on the microscope slide is 
 -sufficient. Creeping is avoided by a line drawn with paraffin. 
 
SOLUTION AND CRYSTALLIZATION. 
 
 123 
 
 9. By careful work a COLLECTION OF CRYSTALS of the 
 more common substances may thus be obtained. The best 
 crystals are comparatively small, and require a magnifier for 
 close study. A trifle of wax, rolled on the head of a pin, serves 
 to support the crystal. The pin stuck into the cork of a speci- 
 men tube mounts and protects the crystal quite nicely. A 
 paper strip as wide as the cork is long, around the tube, forms 
 the proper label. 
 
 10. The study of this subject is very much facilitated by 
 procuring at drug stores a few LARGER CRYSTALS that can be 
 picked out from a drawerful of blue vitriol, alum, nitre, yellow 
 prussiate of potash, potassium sulphate, and the like. Rock- 
 candy, in large crystal groups on strings, is also obtainable at 
 candy stores. A few native crystals from dealers in minerals 
 will greatly add to the value of the collection. 
 
 11. The operations of solution, filtration and crystallization 
 are employed not only in the laboratory, but in chemical works 
 to obtain pure products from impure raw materials (REFINING). 
 Many of these raw materials are transported from hot or desert 
 regions to Europe and the United States to be refined; salt- 
 peter from India, borax from the dead valley of Arizona (for- 
 merly from Thibet to Venice), Chili saltpeter from South 
 America, raw sugar from the tropics. Alum and blue vitriol 
 works are among the oldest establishments producing pure 
 •chemicals. 
 
 12. Most soluble substances are associated not only with 
 insoluble materials removable by filtration, but also with 
 substances merely differing in solubility. The less soluble 
 will crystallize first, the most soluble last; so that by setting 
 .aside of the first crop of crystals, and decanting before the 
 substance wanted is all deposited, very pure materials are ob- 
 tained. This process of FRACTIONAL CRYSTALLIZATION is 
 one of the most simple and effective means for obtaining pure 
 chemical individual substances. 
 
15. CRYSTAL DESCRIPTION. 
 
 1. Magnificent specimens of CRYSTALS are found IN' 
 MINERALOGICAL MUSEUMS— and beautiful, though smaller, 
 crystals of the most varied kind are MADE IN THE LABO- 
 RATORIES. But their forms seem bewildering; no two crystals; 
 of the same substance appear to be exactly alike. 
 
 2. The ancients were familiar with the large quartz crystals- 
 of the Alps and the splendid blue vitriol crystals made in 
 Spain. Pliny speaks of both; the former he considers ice 
 (KRYSTALLOS, in Greek) so hard frozen that heat cannot 
 thaw it (Hist. Nat. 37, 9), the latter he believes to be a glass 
 vitrum, hence our word vitriol (Hist. Nat. 34, 11). It is only 
 in modern days that the characteristic, fixed features in this 
 form of crystals have been discovered. Accordingly we now 
 can describe a crystal in such a way that its form can be 
 identified and recognized by that description. 
 
 3. The Dane STEEN (or Steno) discovered (1669 in Italy) 
 that while the linear dimensions of the six-sided quartz crys- 
 tals varied infinitely (see p. 65) the angles between adjacent 
 faces of that prism (rr) are constant, always exactly 120 
 degrees. Crystallographically, as to these INTER-FACIAL 
 ANGLES, the quartz prism therefore is a REGULAR hexagon 
 of 120 degrees. ROME DE LTSLE (p. 54) and especially 
 HAUY (p. 55) have laid the foundation of crystallography 
 upon this law of Steno. 
 
 4. A CRYSTAL IS A POLYHEDRON FORMED SPON- 
 TANEOUSLY. This is the best and most simple definition 
 that can be given. Its expresses the two fundamental facts, 
 that crystals are bounded by plane surfaces called faces, and 
 form without external influences, the substance being left en- 
 tirely to itself. The line of intersection of two faces is called 
 an EDGE. The point where three or more faces meet is- 
 called a CORNER. 
 
CRYSTAL DESCRIPTION. 
 
 125 
 
 5. Three or more faces having their edges parallel consti- 
 tute a ZONE or PRISM. This prism is limited or cut off by 
 ■one or more faces. If one face, it is called the BASE— right if 
 at right angles to the. edges, oblique if not. If the prism is 
 cut off by two faces under an angle, as the roof on a house, 
 these faces are called a DOME, also right or inclined, accord- 
 ing as the ridge is perpendicular or not to the edges of the 
 prism. If limited by three or more faces, the prism is said to 
 be surmounted by PYRAMID. 
 
 6. The general appearance of a crystal is distinguished as 
 TABULAR or PRISMATIC, according as two dimensions or one 
 only predominates. If a corner or edge is replaced by a face, 
 it is said to be TRUNCATED. If an edge is replaced by two 
 faces, it is BEVELLED. The general predominance of a par- 
 ticular set of forms is called the HABITUS, and depends on the 
 special conditions under which the crystals grew. See 10, 9. 
 
 7. The interfacial angle of »a crystal can be determined . 
 with sufficient accuracy for all purposes of identification by my 
 diagram GONIOMETER (p. 68) for student’s use. Hold the 
 edge of the crystal so that it appears as a point, and the two 
 faces as lines — then the edge will be vertical to the paper 
 goniometer, and it will be easy to find the angle most nearly 
 identic with the interfacial angle concerned. 
 
 8. The crystal is held mounted on a pin or by means of 
 forceps, and the eye may, for small crystals, be assisted by a 
 magnifying glass of low power, that is, if long focus. Both 
 large and small crystals are readily measured in this manner. 
 After some practice, the nearest degree can be ascertained, 
 though in description the TENTH of a degree will be stated 
 for reference. Thus calcite is about 105 degrees; exactly 
 105.1 degrees. 
 
 9. BLUE VITRIOL (p. 68) crystals show the dominant 
 zones MT 123.2, PT 127.7 and MP 109.2. In the first zone 
 the faces n, I, r replace edges, so that Tr 110.2, Tn 148.8, 
 
 Mr 126.7. Also Pn 120.8 and Pr 103.4. 
 
126 
 
 LECTURE 15. 
 
 Special characters: Crystals tabular after M; face T looks 
 rectangular; face N is frequently striated parallel to edge MT ; 
 and face P in coarse crystals shows curved projections due to 
 disturbed rapid growth. These forms are evidently triclinic, 
 destitute of symmetry; 10, 3, note. 
 
 10. Nitre (p. 68) forms right prisms, M M'b, very nearly 
 hexagonal; MM' 119.4, Mb 120.3. The right dome D meas- 
 ures 109.8 and Db 125.1. Crystals often tabular after b. 
 ALUM is octahedral (O) with corners (hexahedron, H) and 
 edges (dodecahedron, D) truncated. OO 109.5, OH 125.3, 
 OD 144.7, and HH 90.0, DD 120.0 Crystals commonly grow 
 resting on a face of the octahedron, and thus show rhombo- 
 hedral appearance, the three D forming a rhombohedron of 
 120 and the three H one of 90 degrees. 
 
 11. THE FERROUS SALT (hydrated ammonio-ferrous 
 sulphate) forms tabular crystals, the oblique base P dominat- 
 ing and striated. The prism MM' about 109, and MP=M'P 
 about 105 degrees. The characteristic triangular truncatures 
 q form Pq about 155 degrees. 
 
 These crystals form very readily by mixing strong. solutions 
 of ammonium sulphate and of ferrous sulphate (green vitriol) ; 
 even a drop each on the microscope slide will suffice. This 
 double salt is permanent in air; green vitriol is not. 
 
 12. The ferrous (pale green) solution may be replaced by 
 nickel (deep green), cobalt (pink), manganese (pale rose), 
 copper (deep blue), or the colorless solution of magnesium, 
 zinc or cadmium sulphates. In all cases, these solutions will, 
 with ammonium sulphate solution, give crystals of the same 
 general form and nearly the same angles; such compounds are 
 called ISOMORPHOUS. The habitus may be more prismatic 
 or more tabular, according as MM' or P dominates. Isomor- 
 phism was discovered by ElLHARD MlTSCHERLlCH (1794- 
 1863) ; portrait p. 34. 
 
16. MARBLE AND FIXED AIR. 
 
 1. CALCITE in all its natural varieties, down to the common 
 limestone, has the property of promptly effervescing with vine- 
 gar ; a drop of vinegar placed on the specimen produces the ap- 
 parent boiling up (11,9). In a test tube this shows better; in 
 large cylinders and flask the phenomenon becomes very strik- 
 ing. It is also advisable to take a common mineral acid, like 
 muriatic or nitric acid instead of vinegar. Sulphuric acid 
 cannot be used, giving a precipitate with lime solution. 
 
 2. TO STUDY THE GAS set free in this effervescence, it is 
 necessary to produce it in quantity and to collect it. The 
 most convenient generator is Kipp’s, because it will yield the 
 gas exactly as it is required. The upper compartment is 
 charged with clean fragments of marble as large as can be in- 
 troduced through the tubulature. The acid is dilute muriatic, 
 3 water to 1 acid. We remove the lower glass stopper, re- 
 place it by a rubber stopper (well tied or wired) connected 
 with rubber tube, as shown. Then the pressure can be 
 promptly released at the close of the working hours. 
 
 3. THE GAS is drawn by slightly turning the delivery 
 stopcock. It may be collected in cylinders over the pneu- 
 matic trough or in empty gas washing bottles; best the 
 Drechsler form made entirely of glass. A series of such 
 cylindrical washing bottles may be connected by rubber tubes 
 and thus the different reactions of the gas shown at one 
 view. These cylindrical bottles are easily detached by the 
 ground joint, so that the reagents can be introduced at any 
 time. 
 
 4. COLOR, ODOR, TESTS. The gas collected over the 
 water or in the washing cylinders cannot be distinguished by 
 sight from the air surrounding the apparatus — it is colorless. 
 Nor has the escaping gas been recognized by odor — it is odor- 
 less. In a wash bottle containing blue litmus, a wine red tint 
 
128 
 
 LECTURE 16. 
 
 is produced as the gas passes through— it is soluble in water, 
 and that solution is an acid. In another cylinder, lime water 
 becomes turbid (white precipitate), which increases in amount, 
 finally diminishes again, and dissolves. 
 
 5. This solution, exposed to the air in a shallow vessel, 
 gradually deposits microscopic rhombohedral crystals, exactly 
 of the same form as the calcite rhombohedron of 105 degrees. 
 They effervesce with acids, give the orange tint to the blow- 
 pipe flame, exactly as calcite; they are ARTIFICIAL CALCITE. 
 They show beautiful colors in the polarizing microscope. 
 
 6. THE GAS IS decidedly HEAVIER THAN atmospheric AIR; 
 for it can be poured out of one vessel into another, exactly like 
 water. A little lime water in the lower vessel becomes turbid, 
 especially after shaking. A burning taper at the bottom of 
 the lower cylinder will be extinguished, as the gas is poured 
 into that cylinder — the same as if the taper were lowered into 
 a vessel filled with the gas. The gas does NOT SUPPORT 
 COMBUSTION. 
 
 7. PROPERTIES. The gas set free by an acid acting on 
 calcite thus is colorless, odorless, heavier than air, does not 
 support combustion; it is soluble in water, forming an acid, 
 makes lime water turbid, an excess redissolves the precipitate, 
 .and from that solution the original calcite deposits in perfect 
 rhombohedral crystals. This gas is evidently contained (fixed) 
 in all forms of calcite; it was called FIXED AIR by Black of 
 Edinburgh (1755), who first most thoroughly studied it. 
 
 8. This gas was first produced by VAN HELMONT (1577- 
 1644), who introduced the term GAS; really spirit, ghost 
 (engl.), ghoast (dutch), geist (german)-, gast (anglo-saxon). 
 He called it gas sylvestre (spiritus sylvestris) or wild, savage 
 gas, because he was unable to tame and control it, so as to 
 collect and handle it. (See portrait, p. 30). Since Black, it 
 has been called carbonic acid — but the dry gas itself has no 
 acid properties. Then it was called carbonic anhydride, and 
 
MARBLE AND FIXED AIR. 
 
 129 
 
 now it is quite learnedly called carbon dioxide! Bergman 
 (1774) called it acidum aereum. 
 
 9. BURNING CHARCOAL in a current of air, the product 
 of combustion will show all the properties of fixed air; hence, 
 fixed air contains carbon. In this experiment the charcoal is 
 heated in a tube of Bohemian glass connected with the 
 Drechslers, which are attached to an aspirator, producing the 
 current of air. Air exhaled shows like properties; so does air 
 from fermenting grape juice. 
 
 10. Fixed air has been LIQUEFIED to a limpid, colorless 
 liquid by cold and pressure (Faraday, 1823); but no amount 
 of pressure will liquefy it above 31 degrees. That is, above 
 31 degrees it is a true, non -liquefiable gas; below 31 degrees 
 it is a condensable vapor. This limiting temperature be- 
 tween vapor and true gas is called the CRITICAL TEMPERA- 
 TURE. The pressure sufficient to liquefy it at that temperature 
 is 73 atmospheres. At — 78 degrees, fixed air CRYSTALLIZES 
 to white, snow-like masses (Thilorier, 1835). 
 
 11. LIQUID FIXED AIR (liquid carbonic acid) is now pro- 
 duced in chemical works and sold in steel cylinders to various 
 industries. The solution of fixed air in water, made strong by 
 using from 2 to 5 atmospheres pressure, is used as a refresh- 
 ing beverage (soda water) ; it is also produced in the portable 
 fire-extinguishers and chemical fire engines. Many natural 
 spring waters are also stron'gly carbonated, that is, impregnated 
 with fixed air. 
 
 12. RAIN DROPS ABSORB FIXED AIR while falling, and 
 while sinking through the soil. Reaching the rocks below, 
 the water will slowly dissolve limestone, become hard — de- 
 positing kettle stone when boiled. Such rock-water, reaching 
 fissures or cavities, will lose its fixed air and deposit the lime- 
 stone it. held in solution as calcite, often finely crystallized. 
 Thus chemical changes (METAMORPHOSES) are going on in 
 the depths of the earth. 
 
17. ZINC AND INFLAMMABLE AIR. 
 
 1. Iron is insoluble in water; iron pipes are used for 
 water conduits in cities. But if to the water standing over 
 scrap iron, oil of vitriol be gradually added, effervescence will 
 promptly start up; an inflammable gas of unpleasant odor 
 will escape in abundance. Paracelsus (1493-1541) has first 
 described this quaintly: Air rises and bursts forth like a 
 wind. BOYLE (1626-1691) first collected this gas. See 
 portrait p. 21. 
 
 2. Cavendish (1731-1810) first carefully studied this gas 
 which he called INFLAMMABLE AIR. He found it colorless 
 and odorless (when pure); the lightest of all gases (1765); 
 inflammable, producing water when burning. With air it 
 forms an explosive mixture. Hence, great care is required 
 when handling this gas near any flame; the explosions are 
 violent, so much so that Lemery thought (1675) thunder 
 due to the “ fulminations ” of this gas. 
 
 3. TO GENERATE INFLAMMABLE AIR in quantity, charge 
 a Kipp with ordinary granulated zinc and dilute muriatic acid. 
 Collect a cylinder full (100 or 200 cc) over the through, and 
 carry the filled cylinder to a flame — the gas will explode. Let 
 the Kipp be emptied a few times, filling up by closing the 
 stop-cock. Trying another cylinder of the gas now collected, 
 it will burn quietly, without explosion ; this is a sign that 
 the gas is free from air. 
 
 4. THE EXTREME LIGHTNESS of the inflammable air is 
 shown by holding a cylinder containing air for a few moments 
 over a cylinder containing the gas, and now trying both at the 
 flame, the gas in both will burn with explosion. 
 
 Careful determinations have shown that under ordinary 
 conditions (of temperature and pressure) twelve cubic centime- 
 ters of inflammable air weigh one milligramme (0.083 mgr. 
 per cc). 
 
ZINC AND INFLAMMABLE AIR. 
 
 m 
 
 5. The gas generated from zinc has not as unpleasant an 
 odor as that generated from iron; it is less impure. TO 
 PURIFY A GAS it must pass slowly through absorption and 
 washing tubes, containing the proper absorbents. If these 
 are in the liquid form, it requires pressure to force the gas 
 through; hence, it is generally preferable to soak fragments 
 of pumice with the absorbent liquids and pack these frag- 
 ments in cylinders. 
 
 6. The most effective ABSORBENTS for purifying inflam- 
 mable air are lead and silver solutions (removing the odorous 
 gases), caustic potash solution (removing traces of acids) and 
 concentrated oil of vitriol one of the most effective dryers, 
 being strongly hygroscopic. 
 
 7. For such purposes the Drechslers are not applicable. 
 We generally use cylinders of glass, on foot, so they will 
 stand firmly, and provided with a tubulature in a lower 
 division, separated from the main upper parts by a narrow 
 contraction, preventing the fragments of pumice from falling. 
 Connection is made by rubber stopper and glass tubing at the 
 top opening and at the tubulature below. A number of such 
 cylinders are used in series. 
 
 8. If the inflammable air is carefully dried so that it will 
 pass through a tube surrounded with fragments of ice without 
 depositing moisture in the same, it can be connected with a 
 small burner (like the microchemical burners) and, after due 
 precautions, the jet may be lit. IT WILL BURN with a pale, 
 very hot flame. A bell glass held over the flame will bedew, 
 and WATER will soon run in drops down into a plate placed to 
 receive it. 
 
 9. Since inflammable gas produces or generates water 
 (Greek: hydor) when burning, it was called HYDROGEN by 
 Lavoisier -(p. 19). The chemical symbol of hydrogen is FI. 
 
 Experience has shown that HYDROGEN IS CLOSELY RE- 
 LATED TO THE METALS, several of which form genuine 
 alloys with it. Palladium absorbs a thousand times its own 
 
132 
 
 LECTURE 18. 
 
 volume of hydrogen (Graham) ; it is used in gas analysis to 
 remove hydrogen from other gases. 
 
 10. In recent days, since very low temperatures have been 
 produced on a sufficiently large scale, it has been found 
 (Olszewski, 1895) that the CRITICAL POINT of hydrogen 
 gas is at 234.5 degrees below the freezing point, and that the 
 critical pressure is 20 atmospheres. Below this temperature 
 hydrogen is a vapor, liquefiable by an increase of pressure. 
 
 11. Any of the acids can he used instead of muriatic, es- 
 pecially nitric, sulphuric and even acetic. THE METAL§ 
 THAT DISSOLVE more or less readily IN some of these 
 DILUTE ACIDS are, in addition to iron and zinc: Magnesium, 
 aluminium, cadmium, nickel, cobalt, lead. The special con- 
 ditions of solution will be studied in due season. Lead is 
 insoluble in both muriatic and sulphuric acids. 
 
 12. In many cases, especially where sulphuric acid has 
 been used, CRYSTALS FORM, in which the blowpipe readily 
 detects the metal originally dissolved. Some of these crys- 
 tals, especially the sulphates, contain water of crystallization, 
 easily driven off by heating the crystals in a glass tube. 
 
 18. SUBSTITUTION BY SOLUTION. 
 
 1. THE CONTRAST between the solution of marble and 
 metals in ACIDS and salts in WATER must have become 
 apparent. When the salt dissolves in water nothing escapes, 
 and upon evaporation, the original salt is reproduced, fre- 
 quently in crystals. When the metals dissolve in acid, a 
 gas escapes, a new substance forms, no longer the metal, 
 but containing the metal, as proved by means of the blow-pipe. 
 
 2. Accordingly we have two different kinds of solution, 
 simple and CHEMICAL SOLUTION, also distinguished as solu- 
 tion and dissolution. The first is largely physical in its 
 nature; the second is entirely chemical, the original sub- 
 
SUBSTITUTION BY SOLUTION. 
 
 133 
 
 stances both disappear and are replaced by two new and 
 totally different substances. Thus we have entered the very 
 center of CHEMISTRY IN THE WET WAY. 
 
 3. In the solution of any metal in a dilute acid, HYDRO- 
 GEN GAS is always produced. The solution obtained in 
 many cases — detailed directions belong to practical chemistry 
 — crystallizes, in all cases can be evaporated to dryness, so 
 that the new salt is obtained by itself, free from water and 
 any excess of acid — the last best avoided by having an excess 
 of metal, and decanting the solution. IN THE SALT, the 
 blowpipe readily detects THE METAL used and dissolved. 
 
 4. For example, in the preparation of hydrogen gas by 
 means of zinc and dilute sulphuric acid, we obtain the gas 
 and a white crystallized salt containing zinc; this salt is iden- 
 tical with common white vitriol. A solution of this salt gives 
 an abundant white precipitate with lead acetate, precisely as 
 does the acid used; it contains, therefore, the essential or 
 chemical characteristic part of sulphuric acid. Hence, it is 
 termed a sulphate, namely ZINC SULPHATE. 
 
 5. The chemical solution considered may now be repre- 
 sented thus: Zinc and sulphuric acid give hydrogen gas and 
 zinc sulphate. Evidently the hydrogen must have formed 
 part of the sulphuric acid. It is known to be metallic in its 
 real nature (17.9). We have here apparently an exchange of 
 metals, hydrogen for zinc; consequently the acid itself must be 
 hydrogen sulphate. In other words, the ACID IS A HYDRO- 
 GEN SALT, exactly as white vitriol is a zinc salt, the salt of 
 a metal. 
 
 G. The above REACTION— that is chemical action — be- 
 tween the metal and the acid may therefore be written as 
 follows: Zinc and hydrogen sulphate give hydrogen and 
 zinc sulphate. Such a reaction in which any substance A 
 takes the place of any other substance B in any combina- 
 tion, setting free this second B, is called a SUBSTITUTION. 
 The above reaction is the substitution of zinc for the hydrogen 
 of the acid. See blackboard diagram. 
 
134 
 
 LECTURE 18. 
 
 7. Having studied the qualitative side of this fundamental 
 reaction, we must next try to determine the QUANTITATIVE 
 RELATIONS of the same. The merest trials show that with- 
 out weighing the quantities used, there either remains metal 
 or acid in excess. To obtain the best salt it is generally 
 advisable to have an excess of the metal, decanting the liquid 
 when th^ reaction ceases and setting the liquid aside to 
 crystallize. 
 
 8. First, TO DETERMINE THE AMOUNT OF HYDROGEN 
 GAS the latter must be measured in a gas burette. The evo- 
 lution tube is charged with an excess of the acid and the 
 accurately weighed metal— the latter held on the slanting 
 walls of the dry, inclined tube above the acid. When the 
 burette is properly adjusted, the operation is started by simply 
 bringing the evolution tube to a perpendicular. 
 
 9. MAGNESIUM ribbon is specially convenient for these 
 determinations. It is found that a cubic centimeter of hydro- 
 gen gas is produced for each milligramme of magnesium used, 
 very nearly. As 12 cc hydrogen gas weigh one milligramme 
 (17.4) THE UNIT OF ONE MILLIGRAMME OF HYDROGEN 
 IS EQUIVALENT TO TWELVE MILLIGRAMMES OF MAGNE- 
 SIUM. 
 
 10. Repeating the experiment with zinc we find that it 
 requires nearly 32 mgr. of zinc to give 12 cc gas representing 
 1 mgr gas, at the same time (under same pressure and tem- 
 perature). For iron the equivalent number is 28. For alum- 
 inium — easiest dissolved in an alkaline liquid (13.5) — the 
 equivalent is found to be 9. Accordingly 1 of hydrogen (by 
 weight) is equivalent to 9 Al, 12 Mg, 28 Fe, 32 Zn (really 
 31.75). These numbers are called the CHEMICAL EQUIVA- 
 LENTS of the metals. 
 
 11. Careful experiments, on a small scale with accurate 
 weighings, show that PER UNIT of weight of metal dissolved 
 in sulphuric acid, THE CRYSTALLIZED SULPHATES WEIGH: 
 For Mg, 10.25; Fe, 4.96; Zn, 4.38; Cd, 2.49. If carefully 
 heated to drive out the water of crystalization, the residual 
 
SUBSTITUTION BY SOLUTION. 
 
 135 
 
 anhydrous sulphates weigh respectively 5.00, 2.71, 2.46 and 
 1.85 times as much as the metal used. Lead converted into 
 nitrate weighs 1.60, into crystalized acetate (sugar of lead) 
 1.83 per unit. 
 
 12. Careful experiments of this kind also permit the deter- 
 mination of the CHEMICAL EQUIVALENTS OF THE ACIDS 
 themselves. Thus, since 1 Mg gives 5.00 dry sulphate, the 
 equivalent 12 Mg gives 60 Mg S^te, in which the non-metallic 
 matter (the S^te) is 60-12=48. But the acid contains H=1 
 as metal or instead of the metal. Hence, the chemical equiv- 
 alent of sulphuric acid, H is 49. In a like manner, the 
 equivalent of nitric acid is found to be 63, and thaf of muri- 
 atic acid, 36.5. 
 
 19. SOLUTION OF SILVER AND GOLD. 
 
 1. Dilute sulphuric or muriatic acids have no effect what- 
 ever on copper, mercury and silver, nor on gold and platinum. 
 All these metals are insoluble in dilute acids. But when 
 heated with CONCENTRATED sulphuric ACID, the first three 
 dissolve, yielding a noxious gas having the odor of burning 
 sulphur; the last two, gold and platinum, remain insoluble 
 even in boiling concentrated sulphuric acid. 
 
 2. Very dilute nitric acid, in the cold, has but little action 
 on the first three metals (Cu, Hg, Ag), but when the acid is 
 reasonably strong — say 10 per cent. — it acts quite promptly, 
 especially when moderately heated. While the metals dissolve, 
 a very noxious reddish gas (RUTILANT VAPORS) is produced 
 in abundance. 
 
 3. The rutilant vapors invariably make their appearance 
 when strong nitric acid exerts its dissolving influence. When 
 a filter paper or sponge with aqua ammonia is brought near, 
 ABUNDANT WHITE CLOUDS take the place of the noxious 
 vapors, which evidently combine with the ammonia to a white 
 solid. In this way, the solution may be effected in a room 
 not provided with hood. 
 
136 
 
 LECTURE 19. 
 
 4. Nitric acid (AQUA FORTIS), even when boiled, has no 
 effect on gold nor on platinum; they are insoluble in all ordi- 
 nary single acids. In fact, gold is generally separated from 
 its alloy with silver, by boiling the alloy with concentrated 
 sulphuric acid or with nitric acid under conditions established 
 by long practice; the amount of gold present must be less 
 than one -fourth in the alloy. This accounts for the common 
 name of nitric acid in german: Scheide wasser. Compare 
 this wet way process with the dry way separation, 8, 12. 
 
 5. AQUA REGIA (4 muriatic with 1 nitric acid) dissolves 
 gold (foil) readily. Both gold and platinum are dissolved by 
 moderately heating them with this acid in large excess. When 
 all metal dissolved, the excess of acid is driven off, carefully 
 avoiding overheating, as that would decompose the MURIATE 
 obtained (test, 13, 10). Dissolving in water, we have the 
 common solutions of these two metals; muriate of gold and of 
 platinum. 
 
 6. The nitrates of copper, mercury and silver are readily 
 obtained in crystal form. Silver nitrate crystallizes generally 
 in rhombic tablets, of almost 130 degrees. Silver and its salts 
 are very sensitive to light and to many gases, and even to 
 dust, so that good, colorless (or white) crystals can only be 
 obtained under specially favorable conditions. 
 
 7. The nitrate of mercury obtained varies with the con- 
 ditions under which the metal is dissolved. When at com- 
 mon temperature, acted upon by dilute nitric acid, the resulting 
 nitrate is precipitated abundantly by the muriatic acid or by 
 salt; it is called MERCUROUS NITRATE. When the metal is 
 acted upon by reasonably strong acid on the water bath, the 
 resulting nitrate is not precipitated by muriatic acid or salt; 
 it is called MERCURIC NITRATE. 
 
 8. The sulphates of mercury show the same difference. 
 Heating the metal with less than half its weight of concen- 
 trated sulphuric acid gives MERCUROUS sulphate; while 
 heating mercury with twice its weight of concentrated acid 
 until the excess of acid is driven off, gives MERCURIC sul- 
 
SOLUTION OF SILVER AND GOLD. 
 
 137 
 
 phate. The distinction is made as before stated; the mercu- 
 rous solutions are precipitated by muriates. The precipitate 
 is CALOMEL; the other muriate is SUBLIMATE. 
 
 9. When trying to dissolve the mercuric sulphate, an 
 abundant yellow precipitate — the TURPETH MINERAL — forms, 
 a so-called basic sulphate, while the balance or acid sulphate 
 passes into solution. By adding about 5 per cent (sulphuric) 
 acid to the water, the entire salt will be dissolved, and no 
 yellow precipitate will form. When it has formed, such 
 addition of acid will redissolve it. 
 
 10. If the residue from copper and concentrated acid is 
 taken up in warm water, the resulting solution will deposit 
 the crystals of blue vitriol described (15.9). 
 
 In this manner ALL METALS HAVE BEEN BROUGHT INTO 
 SOLUTION, excepting the modern light metals potassium and 
 sodium (6.12). Greenish iron solutions in presence of nitric 
 acid become reddish; these are called FERRIC, the original 
 greenish FERROUS. 
 
 11. THESE SOFT METALS have to be kept in well stop- 
 pered bottles under pure naphta, and even then their surface 
 soon looks dull and corroded. When freshly cut with a knife 
 the surface looks brilliant white like silver. Thrown on water 
 the metal floats, melts (round globule) and burns with a pur- 
 ple (Ka) flame, finally exploding; hence, the experiment 
 must be made in a deep beaker with but an inch of water. 
 Sodium is less violent; burns with yellow flame. 
 
 12. The solution so obtained is strongly alkaline. Evapo- 
 rated to dryness and fused, the CAUSTIC ALKALIES are 
 obtained. Made carefully in a large nickel crucible, the ex- 
 periment yields 1.7-1 of caustic soda, 1.43 of caustic potassa 
 per unit- of metal. 
 
 It may also be added that a UNIT WEIGHT OF METAL 
 GIVES 1.44 Ag Sate, 1.57 Ag Nate, 1.60 Pb Nate, 3.94 blue 
 vitriol, 1.48 mercuric sulphate; 1.24 mercurous sulphate; 1.18 
 calomel and 1.35 sublimate. Accordingly, the EQUIVALENT 
 of SILVER is about 108, of lead 104. See 18, 12. 
 
20. REDUCTION IN THE WET WAY. 
 
 1. The four solvents used for the solution of the 
 metals are water, dilute acids, concentrated (single) acids and 
 aqua regia. The type metals, soluble in these solvents, are 
 POTASSIUM, ZINC, SILVER and GOLD. To the most soluble 
 group belong Ka, Na, as shown; also Ca, Sr, Ba. Insoluble 
 in water, soluble in dilute acid are: Mg, Al; Zn, Fe, Pb. 
 Requiring a concentrated acid are: Cu, Hg, Ag. Requiring 
 aqua regia: Au, Pt. 
 
 2. In each of the four groups, the metals have been 
 enumerated according to their DEGREE OF SOLUBILITY. 
 Thus, experience shows that Mg is clearly the most soluble, Pb 
 the least soluble, of those mentioned in the second group; 
 also Zn more soluble than Fe, but less soluble than Al and Mg. 
 
 3. But if into a blue copper solution a piece of iron be 
 thrown, the iron will become covered with red copper and the 
 solution will loose its fine blue color, soon appearing colorless; 
 if exposed for hours to the air, the iron now in the solution 
 will show a rust- like precipitate. Evidently, the more soluble 
 iron has taken the place of the less soluble copper in the solu- 
 tion. We have a substitution of iron for copper. 
 
 4. This rule is general. A MORE SOLUBLE METAL WILL 
 TAKE THE PLACE OF ANY LESS SOLUBLE METAL IN A 
 SOLUTION. A gold solution will deposit its gold upon a piece 
 of metallic silver and be changed to a silver solution. This 
 silver solution will surrender to mercury, a mercury solution to 
 copper, the latter to lead, the lead solution to zinc. 
 
 5. THIS REDUCTION OF THE METALS IN THE WET 
 WAY finds important applications in the arts as well as in the 
 laboratory. Copper-waters issuing in mining regions are 
 run into large reservoirs, and old iron thrown in; after some 
 weeks this iron seems to have been converted into copper. 
 (Hungary) . 
 
REDUCTION IN THE WET WAY. 
 
 131) 
 
 6. In the laboratories, the most elegant and conclusive 
 TEST FOR METALS IN THE WET WAY is this very reduc- 
 tion by substitution. A drop of the solution to be tested is 
 placed on a microscope slide, and a minute clipping of a more 
 soluble metal (generallyzinc) placed in that drop. Almost 
 instantly the substitution takes place, beautiful crystals of the 
 metal in solution growing as it were out from the zinc, form- 
 ing elegant groupings. 
 
 7. Even the alchemists were familiar with these reactions, 
 though some are believed to have considered these simple 
 substitutions evidences of transmutation of copper into silver, 
 of zinc into lead. A dilute lead solution with brass wires and 
 a fragment of zinc, gives the old arbor saturni (LEAD TREE) 
 brilliant crystals of pure lead coating the wires like leaves 
 and branches on a tree. A silver solution with mercury gives 
 arbor dianas, the SILVER TREE, growing up from the mer- 
 cury. 
 
 8. By putting a weighed amount of the more soluble metal 
 into an excess of a solution of the less soluble metal, an 
 EQUIVALENT amount of the latter will be precipitated and 
 can be weighed after proper separation and drying. However, 
 for several pairs of metals it is difficult to get accurate results, 
 the metals changing too readily. 
 
 9. It is found that the silver precipitated weighs exactly 
 nine times as much as the magnesium used; hence the 
 chemical equivalent of silver is 9 times 12 or 108. For every 
 unit of copper thrown into a silver solution, 3.39 units of 
 the latter are obtained from its nitrate solution, especially 
 if the solution is kept in a cool place. The equivalent of cop- 
 per, therefore is 108, divided by this number, or about 31. G. 
 Silver thrown into -a gold solution gives the equivalent of 
 gold about 66. 
 
 10. THE CAUSE of these substitutions is given by the 
 facts of solubility of the several metals taken singly. Thus, 
 copper does not dissolve in dilute sulphuric, while zinc does 
 
140 
 
 LECTURE 21. 
 
 so readily. If copper and zinc together are thrown into the 
 same dilute acid, the zinc will dissolve, the copper not. There 
 can be no question about these facts. Surely, zinc is much 
 more soluble than copper. 
 
 11. Now if metallic zinc be thrown info a solution of blue 
 vitriol, we have THE SAME THREE BODIES — zinc, copper 
 and the dilute acid — in the same dish and the same final 
 result ought to be Obtained, a zinc solution with metallic cop- 
 per. Such is actually the case; zinc displaces the copper 
 from its solution because zinc is much more soluble than 
 copper. 
 
 12. The common talk about CHEMICAL AFFINITIES of 
 these metals is nothing but reasoning in a circle, and the 
 attempt to hide this false reasoning by the introduction of the 
 high sounding term. If zinc has greater affinity for the acids 
 than the copper, nobody knows of that except by the very 
 experiment which it was attempted to explain. 
 
 21. SULPHUR AND SULPHIDES. 
 
 1. Sulphur was known to the ancients. Already, Homer 
 speaks of the purifying effects of burning sulphur (fumiga- 
 tion). Its faint blue flame imparts pallor to the face in the 
 dark. Hence, the ancients burnt sulphur at certain religious 
 ceremonies. 
 
 2. THE OLD CHEMISTS detected sulphur in many ores 
 which upon heating in the open fire, emit the odor of burning 
 sulphur abundantly (9. 3). These ores generally having me- 
 tallic luster, the ancients smelting metals from them, concluded 
 that sulphur is a constituent of metals themselves. Tb change 
 baser metals to gold seemed to the alchemist to involve simply 
 a removal of sulphur or something like sulphur. 
 
 3. SULPHUR continues to be a most important substance 
 to CHEMICAL INDUSTRY. About 400,000 tons, worth 10 
 
SULPHUR AND SULPHIDES. 
 
 141 
 
 million dollars, of native sulphur are produced yearly in Sicily 
 alone, where 25,000 laborers dig for it. 
 
 For many purposes the sulphur of ores is also available. 
 Pyrites contain about 50 per cent, of sulphur, and occur in 
 immense deposits (9. 8). 
 
 4. Native sulphur is a yellow solid, hardness, and 
 gravity very near 2. Its luster is peculiar, resinous. It is a 
 very poor conductor for heat and electricity, and very brittle. 
 Fine specimens (crystals) are' transparent. It is readily fusi- 
 ble (113 degrees), and on boiling (about 450 degrees) forms 
 a brownish red vapor, which condensed gives flowers of sul- 
 phur as sublimate. Melted sulphur, cast in forms, gives roll- 
 sulphur. At about 200 degrees melted sulphur becomes 
 viscid; above that temperature, it gets limpid again. 
 
 5. . Sulphur when absolutely pure has no odor, not being 
 volatile at common temperatures. When heated in the open 
 vessel, it burns with a pale blue flame (250 degrees) far be- 
 low its boiling point; the gas produced is suffocating, of the 
 familiar and characteristic odor of burning sulphur. 
 
 Sulphur is not soluble in water, but quite soluble in essen- 
 tial oils, from which it crystallizes in the forms exhibited by 
 native sulphur. 
 
 6. NATIVE SULPHUR CRYSTALS from Sicily (see p. 69) 
 are very beautiful and often quite large. They are (stable or 
 permanent) rhombic octahedr^; OO' 106.6; sharp edge 85.0; 
 lateral OO" 143.3. Quite generally the sharp corners are 
 truncated by the base P, forming PO 108.4. The sharp edge 
 CB is also frequently truncated by the face q, for which Pq 
 117.8, Oq 132.5 and mutually over middle edge, qq' 124.4. 
 Finally the edges PO are often truncated by an obtuse octa- 
 hedron 0 , for which Po 134.5. The basal rhomb has 101.8. 
 These faces are readily identified even on small crystals from 
 solution. 
 
 7. MELTED SULPHUR CRYSTALLIZES (p. 69) upon cool- 
 ing, forming (unstable) nearly square prisms MM' 90.6, cut off 
 
142 
 
 LECTURE 21. 
 
 obliquely by the base P, so that Pa 95.8, the face a replacing 
 the edge MM'. The lateral corners are often replaced by the 
 triangular faces q, while PM may be truncated by the octa- 
 hedral 0 . Characteristic angles are MP 94.1; Ma 135.3. 
 Pq 135.1; qq' over P 90.3. These dimensions are easily 
 identified. Showing two different crystal forms, sulphur is 
 said to be DIMORPHOUS. 
 
 8. SULPHUR melted or as vapor COMBINES WITH many 
 METALS to new bodies, called SULPHIDES. Several of these 
 artificial sulphides are identic with native sulphides. Copper — 
 in foil or turnings — when reached by the vapor of boiling 
 sulphur, burns brightly. The malleable copper used is thus 
 converted into a very brittle blueish black sulphide. 
 
 9. Mercury, silver, iron, lead, zine and most other ordinary 
 metals combine in a like manner with sulphur. The coarsely 
 divided metals (filings, turnings, thin foil, etc.) need only be 
 melted with sulphur in a crucible. 
 
 Melting together equal weights of iron and sulphur gives 
 the BLACK IRON SULPHIDE, very much used in chemical 
 laboratories; it is distinguished as FERROUS SULPHIDE from 
 the native yellow iron sulphide, pyrite (9, 8). Iron filings 
 mixed with flowers of sulphur, and moistened, also give 
 ferrous sulphide — the mixture may even inflame (Lemery’s 
 Volcano) . 
 
 10. DUMAS (portrait p. 25) exposed pure silver foil in a 
 combustion tube to the vapors of sulphur, and obtained finely 
 crystallized silver sulphide. He found 1.148 of sulphide per 
 unit of silver used. The increase of 14.8 per cent, of silver 
 (equivalent 108) gives 16 as the chemical EQUIVALENT OF 
 SULPHUR. 
 
 11. If fragments of charcoal are heated in a combustion 
 tube while vapors of sulphur are passed over them, a very 
 volatile, highly inflammable liquid is formed, which will con- 
 dense in a cooled receiver. It is called CARBON BISULPHIDE, 
 and is the best solvent for sulphur, taking up nearly half its 
 
SULPHUR AND SULPHIDES. 
 
 143 
 
 weight at common temperatures. From this solution, splendid 
 sulphur crystals can be obtained. 
 
 12. GUN POWDER IS A MIXTURE of sulphur, carbon and 
 nitre in the proportion 1: 1: 6. Washing with water removes 
 the nitre, the identity of which will be revealed by its prismatic 
 crystal form, (15, 10). The well dried residue yields sulphur 
 to the bisulphide, from which fine crystals readily deposit, 
 showing the octahedron O, the base P, and frequently the 
 truncature q, all readily identified by the figures given, using 
 a magnifier. Insoluble, black carbon finally remains. Thus 
 the gun powder was ANALYZED, separated into its constitu- 
 ent parts. 
 
 22. HYDROGEN SULPHIDE AND METALS. 
 
 1. Ferrous sulphide (21.9) covered with almost any diluted 
 acid, gives strong effervescence, both in bulk of gas produced 
 and in odor. The latter is that of rotten eggs. This reaction or 
 chemical process is readily understood. The acid, say H 
 Muriate with Ferrous Sulphide gives HYDROGEN SULPHIDE 
 GAS and Ferrous Muriate remains in the green solution. 
 Rouelle first noticed this gas, which Scheele soon after studied 
 thoroughly. 
 
 2. In this reaction, the substances taken, H Mr^te and Fe^us 
 Side, yielding Fe^^s Mr^te and FI S^^® gas, have evidently 
 interchanged their constituents. They are said to have under- 
 gone DOUBLE DECOMPOSITION— in this case by VOLATIL- 
 IZATION, the product being a gas. Such reactions are very 
 common in chemistry. 
 
 3. HYDROGEN SULPHIDE GAS is quite soluble in water, 
 to which it imparts a strong and highly characteristic odor. 
 When left exposed to the air, such sulphuretted water soon 
 becomes opalescent, and gradually a white deposit forms — this 
 is finely divided sulphur (white streak, substance yellow). 
 Some springs produce such sulphuretted water in abundance, 
 and are very valuable medicinally. 
 
144 
 
 LECTURE 22. 
 
 4. Silver coin and ware, especially when moist, turns 
 black when exposed to the gas or the water; lead paint and 
 compounds of lead, bismuth, silver and other metals, also turn 
 promptly brown or black. Accordingly, hydrogen sulphide is 
 a most IMPORTANT REAGENT by means of which heavy 
 metals can be recognized. During working hours, the chemi- 
 ical laboratories keep this gas on tap in a large Kipp genera- 
 tor for constant use. 
 
 5. A lead solution of ordinary working strength — say one 
 per cent — is perfectly colorless and transparent. A few bubbles 
 of the hydrogen sulphide gas passed into it almost instantly 
 blackens it, forming an abundant black precipitate of Pb Side, 
 settling soon to the bottom. Even when extremely dilute, a 
 brownish coloration will be produced in lead solution by H 
 Side gas. This gas is the most sensitive reagent known for 
 lead in solution. For this reason, lead solutions are replaced 
 by barium solution as reagent for sulphates (13, 12). 
 
 6. The black lead sulphide PRECIPITATE being solid, may 
 be readily separated from the liquid by FILTRATION, and by 
 WASHING, best adding a little hydrogen sulphide to the 
 wash water; drying then removes both water and excess of 
 hydrogen sulphide. 
 
 This precipitate is not only insoluble in water but also insol- 
 uble in dilute acids (nitric, acetic must be tried for sulphuric 
 and muriatic produce precipitates themselves, 13.8). 
 
 7. This reaction evidently again is a double decomposition, 
 for both substances taken interchange constituents. The lead 
 acetate and hydrogen sulphide gas give lead sulphide and 
 hydrogen acetate (acetic acid). But it differs from the pre- 
 ceding case (2) by the product being an insoluble instead of 
 a volatile compound. The present reaction is therefore a 
 DOUBLE DECOMPOSITION BY PRECIPITATION. 
 
 8. It is evident that all SULPHIDES INSOLUBLE IN 
 DILUTE ACID will precipitate by sulphide gas in acidified 
 solutions. The corresponding metals which thus may be 
 
HYDROGEN SULPHIDE AND METALS. 
 
 145 
 
 precipitated as sulphides are, in proper groupings: a) Ag 
 Hgous, pb; b, Cu, Hgic. Cd, Bi; c) As, Sb, Sn; d) Au, Pt. 
 They are distinguished a) by precipitate with muriates (their 
 muriates insoluble) ; c and d, the sulphide precipitates soluble 
 in yellow Am Solution of c colorless, d yellowish. 
 
 9. YELLOW AMMONIUM SULPHIDE is obtained by satur- 
 ating aqua ammonia with hydrogen sulphide gas, and perhaps 
 dissolving some flowers of sulphur in it. The precipitate is 
 tested while still on the filter, but completely washed with 
 water, so that the washing is entirely free from acid reaction (a 
 drop making no red stain on blue test paper). If the acid were 
 not completely removed, it would decompose the reagent, 
 giving hydrogen sulphide gas and an abundant precipitate of 
 sulphur. 
 
 10. The other heavy metals (not precipitated by hydrogen 
 sulphide gas because their sulphides are soluble in dilute acids) 
 do come down when the solution is made ALKALINE by a rea- 
 sonable excess of ammonium hydrate (suificient to give 
 the odor). These metals are f) Zn, Mn, Fe^us, Co 
 and g) Al, Fe’c> Chc- In case of Ferric, the hydrogen sul- 
 phide first makes the solution opalescent (from separation of 
 S) and ferrous, then precipitates this black. 
 
 H. The two groups f and g are readily distinguished by 
 the latter giving a precipitate by ammonium hydrate after the 
 solution has been treated with an excess (as solvent) of am- 
 monium muriate, while the metals grouped under f do not give 
 a precipitate under these conditions i. e. their HYDRATE is 
 SOLUBLE IN SAL AMMONIAC (or ammonium muriate). 
 
 12. THE LIGHT METALS, Ka, Na and Mg, Ca are not pre- 
 cipitated by hydrogen sulphide gas under any conditions, their 
 sulphides being soluble in water. Thus, the metals in solu- 
 tion are almost as readily distinguished by means of hydrogen 
 sulphide gas and a few other reagents as by the blowpipe 
 in the dry way. We shall soon return to this most important 
 subject of CHEMICAL ANALYSIS IN THE WET WAY. 
 
146 
 
 LECTURE 22. 
 
 Note. — The following preliminary tabular exposition of the course 
 IN WET WAY ANALYSIS FOR METALS Comprises only the general reactions 
 determining the groups, and the special features which in these reactions 
 mark the individual members. These are the only reactions sufficiently 
 explained in the preceding. Only one metal is here supposed to be in 
 the solution, which thus contains a simple compound only and is not 
 complex. 
 
 1. Solution -f - 11 Mrate — white precipitate — Silver Group I. Pre- 
 
 cipitate soluble in'much water, Pb ; precipitate soluble in Am Hate. 
 Ag; insol., turning black, Hgous. 
 
 2. Solution-j- 11 Sate, white^precipitate. Barium Group, IF. Very dilute 
 
 solution, no precipitate, Ca; a precipitate forms promptly, Ba, 
 very slowly, Sr. If solution black by H Side, it contains Pb, 
 from r. 
 
 3. Acidified (mur) solution, saturated with H Side gas gives a precipitate 
 
 (other than merely S) . . IH, IV, V. The precipitate washed 
 
 and treated with yellow Am Side remains insoluble, III; or dis- 
 solves IV, V. 
 
 III. Copper Group. Original solution blue or green . , Cu. 
 
 Precipitate first whitish, then yellowish, brownish, finally 
 black . . Hgic; precipitate yellow . . Cd; brown . . Bi. 
 
 Precipitate soluble in yellow Am Side; original solution color- 
 less, . . IV ; yellow to’brownish . . V. 
 
 IV. Arsenic Group. — Color of sulphide precipitate yellow, . As ; 
 orange . . Sb; brownish . . Sn. 
 
 V. Gold Group. — Original solution precipitated brownish by 
 ferrous solution . . Au; yellow by sal ammoniac solution . . Pt. 
 
 4. Solution (3) made alkaline with ammonia after adding considerable 
 
 Am MrMe; a precipitate forms VI or VII. 
 
 Original solution with excess sal ammoniac, made strongly alka- 
 line with Am Hate, np precipitate, VI; a precipitate VII. 
 
 VI. Zinc Group. Original solution, deep green, Ni; pink, Co; 
 pale rose, Mn ; pale green, turning rusty, Feo^s; colorless, Zn. 
 
 Am Side precipitate=white, Zn ; flesh colored, Mn ; black, Feo^s, 
 Ni, Co, distinguished by color of original solution (or dry way 
 borax bead, 6, 1 1). 
 
 VII. Aluminium Group. Original solution, colorless, A1 ; 
 green, Cr; yellow to orange, Feic. The precipitates have nearly 
 the same colors. 
 
 5. If no precipitate obtained : Magnesium group, VIII. Solution with 
 
 much sal ammoniac, made strongly alkaline with Am Hate; to por- 
 tions of this mixture, add 
 
 a) Am Cate; a precipitate forms, or at least on adding Am 
 Oxalate . . Ca from H. 
 
 b) Na pate, white crystalline precipitate . . Mg. 
 
HYDROGEN SULPHIDE AND METALS. 
 
 147 
 
 Original solution or substance, with Ka IDte, odor of ammonia; 
 red paper turned blue . . Am. 
 
 Flame coloration, persistent and intense yellow . . . Na, 
 
 purplish, and through blue glass deep reddish . . . Ka. 
 
 It is understood that the tests are carried on till the substance is found, 
 not beyond (for simple solutions), throughout this course. Thus, if 
 found in reaction i, none of the others is tried; if in 5, reaction gives a 
 precipitate, that ends it. For diagram of this course see p. 73. 
 
 23. IODINE AND IODIDES. 
 
 1 . Iodine is a solid substance which in many respects re- 
 sembles sulphur, especially in its action on metals. While 
 now in the market of chemicals because of its many applica- 
 tions, it was not known till 1811, when COURTOIS discovered 
 it in ashes from sea weeds. It is mainly obtained from the 
 mother liquors of Chili saltpeter. 
 
 2. IODINE is a grayish black solid, sufficiently volatile to 
 make its offensive and characteristic odor perceptible at 
 common temperatures. Its main properties are: G 4.50, F 
 113 and B 180 degrees. Its vapors have a beautiful deep 
 violet (Greek: iodos) color; hence its name and chemical 
 symbol lo. It is sufficiently soluble in water to tinge it yellow. 
 It is more soluble in alcohol, and abundantly soluble in chloro- 
 form and carbon bisulphide. 
 
 3. Both from solution and by sublimation it crystallizes 
 quite readily. On account of its marked volatility, IODINE 
 CRYSTALS are not permanent, but disappear and form again 
 in the containing vessels, according to the changes in tempera- 
 ture. The crystals are rhombic tablets. Compared to the 
 sulphur crystals (p. 69) the angles are OO" 136 and PO 
 112 degrees. 
 
 4. Starch paste is colored deep blue by iodine; the 
 color disappears on heating to about the boiling of water, but 
 promptly re-appears on cooling. This reaction is one of the 
 most delicate or sensitive we have in the wet way. The 
 merest trace of iodine in solution can be revealed by this 
 TEST. One part of iodine in a million of solution will show 
 
148 
 
 LECTURE 23. 
 
 the color with starch paste; in 10 cc of such a solution there 
 is the hundredth part of a milligram of iodine. 
 
 5. Passing hydrogen sulphide gas through a solution of 
 iodine in chloroform or bisulphide under water, the intense red 
 color will gradually disappear and the water will become turbid 
 from sulphur. This is evidently a substitution of iodine for 
 sulphur. lo and H Side giving S and H loide. Decant, filter 
 and by gentle heating drive off the excess of H Side, and a 
 strong solution H loide or HYDRIODIC ACID remains. This 
 colorless solution gradually decomposes, setting free iodine, as 
 indicated by the yellow color it assumes. 
 
 6. Finely pulverized metallic arsenic thrown into a solution 
 of iodine in bisulphide, combines with the iodine, forming 
 ARSENIC IODIDE, which separates in brick red, brilliant, 
 thin tablets upon the volatilization of the solvent. This As 
 lo^de is readily fusible and volatile; it sublimates without 
 decomposition (Synthesis). 
 
 7. Iodine, like sulphur, unites with most metals in the 
 dry way. Heating a glass vessel containing a little mercury, 
 this will deposit, by distillation, in small metallic globules on 
 the inner walls of the vessel. When this has cooled again, 
 heat an equal weight of iodine in the same; as the violet 
 vapors reach the mercury, they combine therewith, forming 
 crystals of MERCURIC IODIDE. 
 
 8. Mercuric iodide can be readily moved from one place to 
 another by heat; it will deposit by sublimation on the colder 
 parts of the vessel. At first it forms YELLOW prismatic 
 crystals of 114.5 degress. Gradually it turns BRILLIANT 
 RED; this change may be produced instantly by rubbing the 
 yellow crystals with any hard body (a glass rod). The red 
 crystals are generally tabular, with a pyramid inclined under 
 1(H). 5 degrees to the base ; hence quadratic (10.3). Mercuric 
 iodide is DIMORPHOUS (21, V). 
 
 9. THE SMALLEST TRACE OF MERCURY may be posi- 
 tively IDENTIFIED in the dry way by applying these reactions 
 
IODINE AND IODIDES. 
 
 149 
 
 in a small blowpipe test tube of hard glass, and observing 
 the results with a magnifier and under the microscope. The 
 metal is identified by the distillate consisting of minute white 
 globules, having brilliant metallic luster. The iodide is next 
 formed by synthesis, its colors and crystal forms recognized. 
 This series of tests is important in toxicology. 
 
 10. Iron, in the presence of water, combines readil}^ with 
 iodine, forming FERROUS IODIDE, which being freely soluble 
 in water, is purified by simple filtration. See 21.9. 
 
 With potassium carbonate, Ka C^te, there will form a pre- 
 cipitate containing the iron (as shown by blowpipe) and from 
 the filtrate, permanent CUBICAL CRYSTALS of potassium 
 iodide are obtained. Fe^us loide and Ka give Fe^us c^te 
 (insol) and Ka lo^^^ (sol). By synthesis, the iron takes the 
 iodine, and by double decomposition this is transferred to the 
 potassium. 
 
 11. Potassium iodide is the most important soluble iodide; 
 by its means the INSOLUBLE IODIDES are readily obtained 
 as PRECIPITATES from the solution of the metals. Thus Pb 
 loide, yellow; hexagonal tablets readily crystallize from solu- 
 tion in hot' water. FIgic red; first pink, then rose, finally 
 brilliant red; soluble in excess of reagent, Ka lo'^^ to colorless 
 solution. Mercurous solutions give dirty green Hgous loUe as 
 precipitate. Ag lo'^^ is yellowis<h white, insoluble in ammonia 
 (distinction from muriate). Bi loi^® is brown. All other 
 iodides are soluble, hence not obtainable by precipitation. 
 
 12. NlTRO-NlTRIC ACID (concentrated nitric acid sat- 
 urated with rutilant vapors, 19.2) instantly SETS FREE TFIE 
 IODINE OF IODIDES; the free iodine may be recognized by 
 its color, solubility in chloroform and the starch reaction, 4. 
 Shaking the solution with chloroform, the free iodine will col- 
 lect in this solvent, tinging it deep red, while the aqueous 
 solution becomes colorless. Now making the solution alkaline, 
 the iodide is reproduced, and the chloroform loses its color. 
 Such operations with NON-MISCIBLE SOLVENTS (as water 
 and chloroform) are very important, especially in toxicology. 
 
24. ACIDIMETRY AND ALKALIMETRY. 
 
 1. Vinegar and lime are the oldest representatives of two 
 important classes of substances endowed with opposite charac- 
 ters; namely ACIDS AND BASES (13). Muriatic, nitric and 
 sulphuric acids correspond to the first; the caustic alkalies to 
 the second. Stronger solutions of these substances are cor- 
 rosive; when exceedingly diluted, the former taste sour (acid), 
 the latter not. Add the strong acid to the water while stirr- 
 ing, when diluting. 
 
 2. But certain coloring materials are most sensitive INDI- 
 CATORS of the presence of either of these bodies, so that the 
 dangerous method of tasting never is resorted to by chemists. 
 The most common indicators are litmus, cochineal and phenol- 
 phthalein. A drop of these solutions show even with exceeding 
 dilute solutions of acid or base: litmus, red and blue; cochin- 
 eal, orange and purplish red; phthalein, colorless and deep red. 
 
 3. Pure water, alcohol and kindred liquids do not change 
 the color of these indicators. Such liquids are said to be neu- 
 tral, or to have a neutral reaction. The extreme sensitive- 
 ness of the indicators or the extraordinary DELICACY OF 
 THE REACTION may be shown by adding a single drop of 
 dilute alkali solution to half a beaker full of water tinted 
 ruby red by a drop of cochineal tincture; on stirring it turns 
 instantly purplish red. A drop of an equivalent acid solution 
 turns it ruby red, the next turns it orange. 
 
 4. THESE CHANGES CAN BE REPEATED an indefinite 
 number of times, most conveniently by having acid and base 
 in two BURETTES. The liquid must be well mixed after the 
 addition of each drop, best by giving a circular motion to the 
 beaker glass. The change will be sudden upon the addition 
 of a single drop; really half of this drop saturates the remain- 
 ing acid, the other half causes the final change in color or 
 reaction. 
 
ACIDIMETRY AND ALKALIMETRY. 
 
 151 
 
 5. In this manner THE RELATIVE STRENGTH or chemical 
 equivalents of given solutions of acid and bases are readily 
 DETERMINED. Suppose that 5 cc of an acid solution, with 
 water and phthalein, shows no change upon the addition of 
 7.8 cc of alkali, but at 7.85 suddenly turns red; then 7.85 cc 
 of this alkali are equivalent to 5 cc of the acid. This alkali 
 solution is accordingly 1.57 times as strong as that acid. 
 
 6. If now the strength of the acid be known, that of the 
 alkali will have become determined by the operation. In 
 VOLUMETRIC CHEMICAL ANALYSIS the unit of the strength 
 of solutions is NORMAL (N), and CONTAINS ONE MILLI- 
 GRAMME-EQUIVALENT PER CUBIC CENTIMETER. If the 
 acid used above was normal, then the alkali found is 1.5 N. 
 The equivalent of sodium hydrate being 40 (as we soon 
 shall learn), it would contain 1.57 times 40 or 62.8 mgr. per 
 cc in the above instance. This is ALKALIMETRY. 
 
 7. The unit of the chemical equivalent being hydrogen 
 (18, 9, 10) the strength of the acid is established by MEASUR- 
 ING THE HYDROGEN GAS evolved from a measured volume 
 of the acid acting upon an excess of magnesium ribbon. Thus, 
 suppose that 5 cc of the dilute acid had been taken, and 75 cc 
 hydrogen gas had been obtained, while a considerable amount 
 of magnesium remained undissolved; then 1 cc acid gave 
 15 cc gas or the acid is 1.25 N. This is ACIDIMETRY. 
 
 8. If a number of careful determinations concordantly give 
 that result (1.25 N), a stock of NORMAL ACID will be ob- 
 tained by diluting 100 cc to 125 or adding to a liter of the acid 
 a quarter liter of water. Since the equivalent of sulphuric 
 acid is 49 (18.12), the normal acid, if sulphuric, contains 49 
 mgr of acid per cubic centimeter; if nitric, 63 mgr; if muriatic. 
 36.5 mgr. 
 
 9. Having thus obtained a stock of normal acid, it is easy 
 to prepare a corresponding stock of NORMAL ALKALI (see 
 6). With these normal solutions the unknown strength of 
 acids and bases is determined in the manner indicated. As a 
 
152 
 
 LECTURE 24. 
 
 matter of fact, the specific gravity of normal hydrates (Ka or 
 Na) is about 1.044, of sulphuric and nitric acids' about 1.032 
 and muriatic about 1.016. Hence, if solutions run from 1.05 
 to 1.10 they are suitable for making normal solutions. 
 
 10. Not one of these alkalies or acids is obtainable in the 
 free state in exactly weighable condition; hence, the pre- 
 ceding method of standardizing by means of an accurately 
 weighed metal is necessary. It has, however, been found, 
 that pure and CRYSTALLIZED OXALIC ACID is permanent 
 in air, when kept in well stoppered bottles. Numerous and 
 careful experiments have shown its equivalent to be 63. By 
 evaporating a normal solution of pure caustic alkali in a silver 
 dish and fusing the residue, the equivalent of caustic soda is 
 found to be 40, that of caustic potassa 56, approximately. 
 
 11. Hence, 63 mgr of crystallized oxalic acid, represents 1 
 cc normal acid. TO TEST ANY ALKALI SOLUTION, it is only 
 necessary to weigh off as accurately as possible, say 630 mgr 
 of such crystallized oxalic acid, transfer to beaker, add water 
 and indicator (best phthalein) ; this represents 10 cc N. If 
 now the alkali is run in— first rapidly, then drop by drop— and 
 suddenly turns the liquid permanently red when 9.85 have 
 been used, it is not exactly normal, but 985 cc filled up to a 
 liter, will be normal. 
 
 12. The books generally recommend the proportion of nor- 
 mal solution of oxalic acid; this is inadvisable for many rea- 
 sons. The above manner of using the pure acid BY WEIGHT 
 IS by far the best and MOST ACCURATE. If a solution is 
 wanted, only half normal should be made, since a normal 
 oxalic acid solution is almost saturated. 
 
 Starting with oxalic acid, the normal alkali will be obtained 
 first, and by its means the normal acid for use. 
 
25. NEUTRALIZATION AND CALORATION. 
 
 1. THE NORMAL SOLUTIONS, prepared according to the 
 methods indicated, are very useful. They permit the ready 
 determination of the strength of given substances, as shown. 
 They also enable us to establish chemical laws and determine 
 important chemical equivalents. 
 
 2. Mixing equal volumes — measured by burette or pipette — 
 of normal solution of base and acid, we obtain a NEUTRAL 
 substance in solution; the process is called NEUTRALIZATION. 
 If we take 10 cc N nitric acid and add 10 cc N potassium 
 hydrate — careful evaporation will soon show the formation of 
 the familiar prismatic CRYSTALS of potassium nitrate (15.10). 
 In the same manner, sodium hydrate and muriatic acid yield 
 the cubical crystals characteristic of sodium muriate or salt 
 ( 11 . 8 ). 
 
 3. If the mixed solution is carefully distilled, a salt residue 
 remains in the flask, and the distillate is pure water. Accord- 
 ingly, Ka Hate and H Nate giving Ka Nate and H Hate by double 
 decomposition, (22, 2, 7) , this HYDROGEN HYDRATE FORMED 
 IS WATER. That is, equivalent amounts of acid and base 
 neutralize each other, forming a- salt and water. Thus we 
 have a third kind of double decomposition, namely by neu- 
 tralization. 
 
 4. If say 10 cc of normal solution are taken, the amount of 
 the compound is exactly 10 milligramme-equivalents (24, 6). 
 The mixture carefully evaporated to dryness or to crystalliza- 
 tion, and completing the crystallization by spontaneous 
 evaporation — the weight of the salt formed represents also 10 
 mgr. equivalents, and will allow the DETERMINATION OF 
 THE EQUIVALENT OF THE BASE if that of the acid is known. 
 The salt is the acid in which hydrogen has been replaced by 
 the metal ( 18, 6) . 
 
154 
 
 LECTURE 25. 
 
 5. Thus 10 cc normal solution of pure Ka H^te and as 10 cc 
 normal solution of H yield 10 milligramme-equivalents of 
 crystals of potassium nitrate; the residue weighing 1010 mgr, 
 the equivalent of Ka is 101. But that of H is 63, 
 (18, 12) ; the difference 101 — 63=38 represents the excess of 
 the equivalent of potassium over that of hydrogen displaced. 
 Hence the EQUIVALENT OF POTASSIUM is 39. The corres- 
 ponding residue of the sulphate is 870 mgr, that of the muriate 
 745 mgr; they give the same value for Ka. 
 
 6. Corresponding determinations with normal sodium 
 hydrate solutions give the CHEMICAL EQUIVALENT OF SO- 
 DIUM 23. In the same manner, the equivalent of AMMONIA 
 is found to be 18. 
 
 For sodium, direct determinations of the equivalent are pos- 
 sible, though not as accurate, because the fresh cut sodium 
 corrodes quite promptly, and the action of the water is rather 
 too violent. See 18, 8, taking water instead of dilute acid.' 
 
 7. Instead of measured amounts of normal hydrates, care- 
 fully weighed amounts of CARBONATES (16, 3) may be used 
 exactly as the metal in 18, 8. If the carbonate is in form of 
 crystal or cleavage piece (calcite), the solid may be placed on 
 the slanting dry wall of the tube, as was the metal. If a 
 powder, it may be weighed in a small porcelain boat, and this 
 ■placed in the tube. 
 
 8. In this way, 12 cc gas (fixed air) are obtained from the 
 following number of milligrams of NATIVE CARBONATES: 
 magnesite 42, dolomite 46, calcite 50, siderite 58, smithsonite 
 63, strontianite 74, witherite 98, malachite 110, cerussite 
 133.5. Also from the following amounts of ARTIFICIAL CAR- 
 BONATES: Na 53, Ka 70, Cd 86, Hg'c 130 and bicarbonates: 
 Na 42, Ka 50. All these weights are RELATIVELY EQUIVA- 
 LENT, producing the same amount of fixed air. 
 
 9. It is easy to show that these numbers are true equiva- 
 lents, or that EQUAL VOLUMES OF FIXED AIR AND HYDRO- 
 GEN ARE EQUIVALENT. For if equivalent, the values for 
 
NEUTRALIZATION AND CALORATION. 
 
 155 
 
 Na and Ka carbonates give upon subtracting the equivalent of 
 the metal (23 and 39) the same number 30 as the equivalent 
 for Xhis subtracted from smithsonite, siderite, cerussite 
 
 leaves for the metals Zn, Fe, Pb, the numbers 33, 28, 103.5, 
 precisely as found before (18, 10 and 19, 12). 
 
 10. Accordingly, THE EQUIVALENT of C^te is 30, and fixed 
 air is equivalent with hydrogen, measure for measure. For 
 dolomite 46, the metal equivalent is 16 which is half of that of 
 the constituent metals Mg 12 and Ca 20. In the same way 
 sodium bicarbonate gives 12 and potassium bicarbonate 20, 
 exactly half the sum of the metal and hydrogen. From cal- 
 cium we find 20, from calcite 50. 
 
 11. When equal volumes of normal acid and base are 
 mixed, THE TEMPERATURE RISES ABOUT 7 DEGREES; a 
 trifle more with sulphates, a little less with muriates. The 
 unit of heat is the gramme-degree (gr°), the amount of heat 
 required to raise the temperature of one gramme (cc) of water 
 one degree (centigrade). Using 100 cc of each, 1400 gr° heat 
 are produced by 100 milligramme-equivalents of acid and 
 base. ' 
 
 12. One milligramme-equivalent of base uniting with one 
 milligramme-equivalent of acid therefore produces a CALORA- 
 TION OF ABOUT 14 GRAMME-DEGREES OF HEAT in forming 
 a salt. Here only the soluble bases (alkalies) have been con- 
 sidered. Numerous accurate determinations of caloration have 
 been made by THOMSEN of Copenhagen and BERTHELOT 
 of Paris. 
 
 26. FLUX AND GLASS. 
 
 1. MANY SUBSTANCES ARE INSOLUBLE IN WATER AND 
 IN ACIDS, even upon boiling. Quite a number of silicates 
 and some precipitates are of this kind. Such are most of the 
 gems (10) and the minerals Nos. 7 to 12 in 11, 5. Barium 
 sulphate and silver muriate are the most common precipitates 
 
156 
 
 LECTURE 26. 
 
 insoluble in acids. To examine such materials in the wet 
 way, they must be brought into solution. 
 
 2. To effect this, the insoluble material is most finely 
 pulverized and mixed with a large excess of alkaline carbon- 
 ates. The mixture is fused (FLUXED) in a platinum vessel, 
 and maintained in the liquid state for some time. Ordinarily 
 a DOUBLE DECOMPOSITION BY FUSION takes place, so that 
 the cooled mass is partly soluble in water, and the residue 
 left by water is soluble in acids. 
 
 3. For example, the absolutely insoluble Ba S^te precipi- 
 tate, mixed with a large excess of Ka C^te gives, upon pro- 
 longed fusing, a mass from which water readily extracts the 
 excess of Ka taken and the Ka S^te formed by double de- 
 composition. The residue of Ba C^te is insoluble in water, 
 but readily soluble, with effervescence, in nitric acid, giving 
 Ba in aqueous solution. 
 
 4. The excess of Ka in the first aqueous solution is 
 removed by adding nitric acid until effervescence no longer 
 takes place; then Ka only is present in addition to the 
 Sate, which in no way can interfere with the testing fpr 
 that Sate. 
 
 5. In the same manner, Ag Mrate, fluxed with Ka Cate, 
 yields Ka Mrate, which is extracted by water, together with 
 the excess of Ka Cate taken. The residue of Ag Cate, in- 
 soluble in water, is readily dissolved by dilute nitric acid, 
 giving Ag Nate. Thus also here, the acid is found in that 
 portion of the flux soluble in water, the metal in that portion 
 insoluble in water, but soluble in acids. 
 
 6. SILICATES, M Siates, fluxed in the same manner, give 
 Ka Siate and M Cate. In this case, the entire fluxed mass is 
 treated directly with dilute muriatic acid, causing the effer- 
 vescence of fixed air and the separation of silicic acid in the 
 GELATINOUS CONDITION. Evaporating to dryness, heating 
 the dry residue gently till all acid vapors are driven off, the 
 
FLUX AND GLASS. 
 
 157 
 
 metallic muriates will be taken up in water, while SILICA will 
 remain, being insoluble. 
 
 7. In general, the compound insoluble in acids may be 
 represented by M Rate, where M designates the metallic, R the 
 non -metallic constituent. Fusing with excess of Ka Cate 
 gives, by double decomposition, M Cate (insol.) and Ka Rate 
 (sol. in water), together with the excess of Ka Cate not 
 changed. 
 
 As a MIXTURE of Na and Ka carbonates is much more fusi- 
 ble than either carbonate taken singly, the mixture is preferred. 
 Not less than four times the weight of the substance should 
 be taken. 
 
 8. In some cases, it is advisable to add other fluxes to the 
 carbonates or to take other fluxes instead; but the process 
 remains essentially the same, namely, a double decomposi- 
 tion by fusion. 
 
 For simple' TESTING, it suffices to fuse a little of the in- 
 soluble substance into a soda bead on the platinum loop. 
 
 9. The silica (6) dissolves readily in a soda bead on fusion, 
 under lively effervescence of fixed air. This is a very simple 
 test for silica. With enough silica, the bead remains trans- 
 parent when cold; in fact, a GLASS has been formed.^ This 
 glass being soluble in water, is called SOLUBLE GLASS. It is 
 manufactured in quantity for various applications. 
 
 10. Ordinary GLASS, not soluble in water, nor in acids, is 
 an AMORPHOUS DOUBLE SILICATE of Na and Ca (window 
 glass) or Ka and Ca (crown glass). Flint glass contains also 
 lead silicate. The carbonates mixed in proper proportions 
 with silica, when fused and slowly cooled, give true, amorphous 
 glass; when rapidly cooled, crystallization may take place, 
 resulting in an opaque mass — not a real glass. 
 
 11. The quality of the glass produced depends on the 
 proportion of the essential materials and their purity. Common 
 
158 
 
 LECTURE 27. 
 
 bottles have to be very cheap — hence they are made from 
 lowest grade materials. 
 
 COLORED GLASS is obtained by small additions of metallic 
 
 calxes, which dissolve, pro- 
 ducing the same colors 
 permanently as shown in 
 the borax bead for a short 
 time only. The Egyptians 
 made good glass, mainly 
 colored ; the cut represents 
 specimens thereof. Com- 
 pare 5, 6. 
 
 12. SILICA, being absolutely non-volatile in our furnaces, 
 drives out all other non -metallic constituents from salts, when 
 heated therewith; for these non-metallic constituents are 
 volatile, and thus cannot remain at such temperatures. Silica 
 drives out all other constituents, not because it is stronger, or 
 has greater affinity, but simply because it cannot get away, 
 while the others, being volatile, can escape from the fiery 
 furnace, and do so. 
 
 27. METALS AND RADICALS. 
 
 1. Having become familiar with the principal chemical pro- 
 cesses and a considerable number of chemical substances, 
 both native and artificial, it seems advisable to recapitulate a 
 few of the general facts in order to find the best way forward 
 in the study of chemistry. 
 
 2. First of all, we have learned to distinguish on INDI- 
 VIDUAL CHEMICAL SUBSTANCE from all sorts of mere mix- 
 tures. The crystal form, specific gravity, fusing and boiling 
 point, and other properties, give as many criteria for the recog- 
 nition of the individual chemical, and if need be, as many 
 
METALS AND RADICALS. 
 
 159 
 
 methods of separation and purification expressed by the gen- 
 eral term of FRACTIONING. 
 
 3. In this manner the metals, salts and acids have pre- 
 sented themselves as CLASSES or FAMILIES of chemical 
 individuals. The metals, possessing that peculiar luster 
 (metallic) and malleability. The salts, generally crystallizing 
 from aqueous solution and by the blowpipe revealing the 
 presence of a metal. The acids, dissolving metals under the 
 evolution of hydrogen or other gases, with the production of 
 salts. 
 
 4. The study of the solution of metals in dilute acids re- 
 vealed the fact, that acids are hydrogen salts, or that the 
 hydrogen in the acids corresponds to the metals in the salts. 
 Solution of a metal in an acid is simply a substitution in ab- 
 solutely FIXED PROPORTIONS BY WEIGHT, termed equiva- 
 lents. These are referred to hydrogen as unit, or Mg as 
 twelve (18, 10). 
 
 5. The salts and acids are evidently DUAL BODIES, con- 
 sisting of TWO component parts. First, the metal in salts 
 and the corresponding hydrogen in acids. This component 
 we shall call the METALLIC CONSTITUENTS of salt and 
 acid; for hydrogen is metallic in its character. The other 
 constituent is NON-METALLIC, the salt and the acids re- 
 sponding to the same tests. 
 
 6. Thus, a drop of sulphuric acid, added to an acidified, 
 dilute solution of barium nitrate, produces a white precipitate; 
 so does the salt obtained by dissolving zinc or magnesium, or 
 any other metal, in sulphuric acid. All these chemicals are 
 therefore SULPHATES, namely H S^te, Zn S^te,-]V\g sate, etc. 
 Now the question arises, what is this S^te? 
 
 7. We have abundant evidence that this S^te is volatile, 
 and we can prove that it contains sulphur, both by SYNTHE- 
 SIS and by ANALYSIS. Burning sulphur in a tube, carrying 
 
160 
 
 LECTURE 27. 
 
 the product of combustion through water, that water will soon 
 give the reaction of sulphates with barium solutions, especially 
 if a shaving moistened with concentrated nitric acid is placed 
 in the course of the gas produced. Simply heating green 
 vitriol in a glass tube, the odor of burning sulphur becomes 
 manifest; that is, the green vitriol must contain sulphur. 
 
 8. But we also know that the non -metallic is not sul- 
 phur merely — for we have obtained copper sulphide by syn- 
 thesis (21.8) and found it entirely different from blue vitriol, 
 which is a sulphate. 
 
 Consequently the non -metallic constituent of sulphates con- 
 sists of sulphur and something else; it is a complex material, 
 called a RADICAL. is the radical of sulphates. 
 
 9. We have already determined the equivalent of this rad- 
 ical, and can now determine the equivalent of its constituents. 
 The equivalent of sulphuric acid we found to be 49; but if H 
 
 is 49, the radical has the equivalent 48. It con- 
 tains sulphur; but S=16, leaves for the unknown part of the 
 Sate radical the equivalent 32. 
 
 10. In a like manner we have found the equivalent of the 
 radical of CARBONATES to be Gate 30 (25.10). We know, 
 by synthesis (16.9), that it contains carbon. 
 
 NITRATES of all kinds, being derived from nitre (13.9) or 
 Ka Nate, contain the radical Nate, the equivalent of which is 
 62. The radical Mrate (MURIATE) has the equivalent 35.5, 
 carried from common salts (18, 12). The exact nature of 
 these radicals is also unknown. 
 
 11. But while the composition of these radicals of salts and 
 acids is unknown, we can practically answer all questions 
 about their ordinary reactions. If we wish to know how much 
 salt is required to precipitate a given amount of silver nitrate, 
 and how much silver muriate will be obtained, we have all the 
 data required in the equivalents. Namely, Ag 108, N^te 62, 
 
METALS AND RADICALS. 
 
 ICl 
 
 Mrate 35.5, Na 23. Accordingly 170 Ag requires 58.5 Na 
 and will yield 143.5 Ag Mr^te. 
 
 12. It is apparent that the sulphides (21) and iodides (23) 
 are compounds of a different order. They consist of only two 
 substances, the metal and the non-metal, S or lo. Such com- 
 pounds are called BINARIES or binary compounds. They are 
 named aS exemplified. The terminal DE (from duo, two) 
 with the essential part of the name of the non-metal (SULPH- 
 ur) by the connecting vowel i. 
 
 28. CHEMICAL REACTIONS. 
 
 1. The principal chemical processes have been shown 
 and employed in the preceding lessons. It will be advisable 
 now to review and classify them. We shall find that but very 
 few really different reactions exist. It must be born in mind, 
 that chemists designate any chemical action by the word 
 REACTION. 
 
 2. Ordinarily, a volatile substance and high temperature 
 cannot co-exist; the volatile substance will escape. Hence, 
 when water or other volatile liquids are present, no high tem- 
 perature can be employed. Practically speaking, all chemical 
 operations are therefore either in the DRY WAY or WET WAY, 
 according as high temperatures or volatile liquids are used. 
 
 3. But if the volatile liquid be enclosed in a vessel strong 
 enough to resist the rapidly increasing pressure of the vapor 
 from within as well as the high temperature applied from 
 without, the distinction between the two ways will become 
 less marked. Since such vessels usually are constructed so as 
 to close themselves more tightly, the greater the pressure of 
 the vapor, they are termed AUTOCLAVES. The first auto- 
 clave was Papin’s digestor. 
 
162 
 
 LECTURE 28. 
 
 4. Work with the auto- 
 clave is both difficult and 
 dangerous. The old chemists 
 had nothing corresponding to 
 this, and modern chemists 
 have restricted its use mainly 
 to organic chemistry. In its 
 simplest form, the autoclave 
 is a strong glass tube, drawn 
 out and closed by fusion, after 
 the charge has been intro- 
 duced. Daubree and Friedel 
 have used the autoclave in 
 mineral chemistry. The first 
 obtained fine crystals of quartz 
 and pyroxene; the latter ob- 
 G. A. DAUBREE. tained feldspars and topaz 
 
 Died May 28, 1896, at the age of 82 years. CryStalS in that Way. 
 
 5. Only THREE really different classes of CHEMICAL 
 REACTIONS can be recognized, namely synthesis, substitution 
 and double decomposition. In synthesis, two substances 
 unite to form a new compound. In substitution, a substance 
 takes the place of one of the two constituents of a compound. 
 In double decomposition, two compounds mutually interchange 
 their constituents, forming two new compounds. 
 
 6. A number of SYNTHESES have been presented in the 
 preceding lectures; especially the formation of sulphides (21) 
 and iodides (23). The conditions under which two substances 
 unite must be specially studied; the degree of temperature 
 required is always an important factor. 
 
 The opposite of synthesis is ANALYSIS, the term taken in 
 its broadest sense of separation. Such reactions will soon 
 come before us. 
 
 7. SUBSTITUTION may involve the metallic or the non- 
 metallic constituent of a compound. When a metal is dis- 
 solved in dilute acids (17) or when reduced in the wet way 
 
CHEMICAL REACTIONS. 
 
 1G3 
 
 (18), it is the metallic constituent which is replaced. When 
 hydriodic acid is formed by hydrogen sulphide (23, 5) it is 
 the non-metallic constituent that is replaced. 
 
 8. Of DOUBLE DECOMPOSITIONS we must distinguish 
 four kinds, namely by neutralization (25, 3), by volatilization 
 (22, 2), by precipitation (22, 7), and by fusion (26, 2). Of 
 these four, the first is erroneously considered a synthesis of 
 acid and base; for water (H H^te) actually forms, as well as 
 the new salt. The last depends largely upon an excess of 
 the flux. 
 
 9. In the case of precipitation, it is clear that insoluble 
 compounds cannot stay in solution; hence two compounds, 
 containing separately the ingredients of an insoluble com- 
 pound, will produce a precipitate when brought together in the 
 same liquid. This rule was first given by Berthollet (p. 32). 
 Accordingly, if an insoluble compound is to be prepared, mix 
 two solutions, the one containing the metal, the other the 
 radical of that compound. 
 
 10. If two substances, containing the constituents of a 
 volatile compound are exposed to a temperature higher than 
 that at which the volatile compound boils, it cannot remain 
 and will pass over as gas or vapor. This is the second rule of 
 Berthollet. — H N^te drives out at common temperature 
 from Ka Side. Xhe Ka N^te remaining, heated on a sandbath 
 with H S^te, gives a distillate of H N^te. Xhe Ka S^te remain- 
 ing, heated to redness with silica, gives a residue of Ka Si^te. 
 The S^te decomposes as it is driven off. 
 
 11. It is therefore of the highest importance to know the 
 VOLATILITY and SOLUBILITY of compounds, in order to 
 understand chemical tests and the methods of preparation of 
 chemicals. The rules of Berthollet then will be the most 
 valuable guides. For example, let Ba S^te be wanted. Being 
 quite insoluble, it will form as precipitate if to ANY Ba Solu- 
 tion we add the solution of ANY sulphate. Therefore, take 
 the common Ba Mr^te and add H S^te^ and Ba S^te ^^\\\ pre- 
 cipitate. 
 
164 
 
 LECTURE 29. 
 
 12. These RULES OF BERTHOLLET (p. 32) even apply 
 to cases merely difficultly soluble. For example, by the Gay- 
 Lussac lines of solubility (p. 70), it appears that the solubility 
 of nitre rapidly increases with temperature, much more so than 
 that of Chili saltpeter, while salt (Na Mr^te) hardly increases 
 in solubility. Accordingly, the high priced Ka is made 
 (by conversion) by dissolving the cheap Stassfurth Ka Mr^te 
 (Ka Clide on Chart) in boiling water, and adding cheap Chili 
 saltpeter; common salt will separate, and from the hot solu- 
 tion nitre will crystallize on cooling. 
 
 Note. — Diagrams of Reactions should be written out in the sim- 
 plest possible manner. The essential features of the reactions should be 
 specially marked, namely insolubility, volatility, etc. The substances 
 actually taken are written one above the other; the determining reac- 
 tion is now marked by one heavy line terminating in an arrow, and the 
 CONSEQUENT REACTION is marked by a light double line. For gases and 
 vapors, the line should be drawn upwards; for precipitates the line 
 should be drawn downwards, as shown in the few instances here given. 
 The diagram represents four characteristic cases, and needs no further 
 explanation. The student should acquire the habit of writing out every 
 reaction in this manner. 
 
 Complex Reactions are simply two or more of the simple reactions 
 described, succeeding one another at shorter or longer intervals of time. 
 As an example, the gradual change of Ka Side to Ka S^te is shown in the 
 diagram. 
 
 29. COMBUSTION AND PHLOGISTON. 
 
 1. The heat of the sun gives motion to all things on this 
 globe. Without the central luminary, no life could exist on 
 the earth. When man succeeded to make a fire for his own 
 use, he took the greatest step towards civilization. The 
 Greek myth of Prometheus voices' the recollection of the race. 
 
 2. In science, both physical and chemical, heat and light 
 occupy an equally prominent place. In chemistry, heat is one 
 of our principal powers for effecting changes of matter. The 
 operations in the dry way range from blowpipe tests to the 
 
COMBUSTION AND PHLOGISTON. 
 
 165 
 
 smelting of iron and glass in gigantic furnaces. Modern 
 progress largely is brought about by the use of our mineral 
 combustible, coal giving both heat and power. 
 
 3. The phenomenon of combustion itself is one of the 
 greatest questions in chemical science. As the sun seems to 
 rise in the east of the observer, himself at rest in the restful 
 landsc^^pe, so the combustible when burning seems to set free 
 heat in flame (phlox or phlogion) and glow, leaving behind 
 but a little of ashes or calx. The main part of the combust- 
 ible seems to be PHLOGISTON. 
 
 4. But long continued and most careful observation of the 
 stars finally convinced COPERNICUS that it is the sun which 
 is at rest, and not the earth. In a like manner, LAVOISIER has 
 demonstrated, that the combustible does not diminish, but 
 greatly increase in weight during the process of combustion. 
 Lavoisier is the Copernicus of chemistry. 
 
 5. These general reflexions form a necessary introduction 
 to the chemical study of combustion, which we now will enter 
 upon. It will soon become apparent that this term cannot 
 be restricted to flame and fire, but applies equally to phenom- 
 ena of world wide extent, but so slow and so wide diffused, 
 that neither flame nor visible glow attend them. 
 
 6. It was the German chemist GEORG ERNST STAHL 
 (1660-1734) who first (1697 and especially 1717) grouped all 
 phenomena of combustion and tried to explain them by the 
 hypothesis of phlogiston. All combustible materials were 
 supposed to contain' phlogiston; wood, oil, fat, wool, also grain 
 and of mineral materials, metals, coal and especially sulphur. 
 
 7. According to this theory, the metals are compounds of 
 the metallic calx and phlogiston. Heating metallic lead before 
 the blowpipe, it burns, that is, phlogiston is set free; the calx 
 remaining as incrustation on the charcoal, is simply the other 
 constituent of the metal. 
 
 8. Now metals are more or less readily calcinated, that is, 
 more or less combustible, as has been exemplified in the 
 
166 
 
 LECTURE 30. 
 
 seventh lecture. Charcoal is much more combustible than 
 any of the common (heavy) metals. This is evident because 
 we can burn all kinds of coal in an iron stove without con- 
 suming the iron. 
 
 9. In the phlogiston theory of Stahl, the metal must con- 
 tain less phlogiston than coal. Consequently, when metallic 
 calxes, intimately mixed with carbon, are heated, the carbon 
 transfers its phlogiston to the metallic calx. The metal (calx 
 and phlogiston) is reproduced. 
 
 10. But this phlogiston which is supposed to readily leave 
 carbon and unite with the calx to form the metal, was never 
 produced in the free state; and when weighed amounts of 
 metals, like tin, were calcined, they notably increased in 
 weight, as already shown by Jean Rey, a pharmacist of Ber- 
 gerac, in 1629. 
 
 11. When hydrogen gas had been discovered by Caven- 
 dish, it was supposed to be phlogiston, or the fire -matter of 
 Stahl. Cavendish himself remained a defender of the phlogis- 
 ton theory till his death (1810). 
 
 12. For nearly a century this phlogiston theory reigned 
 supreme. The apparently conflicting facts were not recog- 
 nized. Within a very wide circle of facts, the theory seemed 
 to explain everything satisfactorily. Like the Ptolemaic sys- 
 tem of the world, it was considered to be in strict accordance 
 with the everyday testimony of the senses. To doubt it was 
 almost a crime, especially in Germany. 
 
 30. COMBUSTION AND OXYGEN. 
 
 1. It would be very interesting to study the history of 
 the CHEMICAL REVOLUTION (Berthelot) which marked the 
 last quarter of the eighteenth century, but time forbids. It 
 will be necessary to confine ourselves to the most conclusive 
 experiments, independent of their historic order. 
 
COMBUSTION AND OXYGEN. 
 
 1G7 
 
 2. A weighed piece of magnesium wire, burnt over a 
 weighed dish, will show quite a large INCREASE IN WEIGHT, 
 though the violence of the combustion makes a partial loss of 
 the calx unavoidable. Under most favorable circumstances, 
 this increase in weight is about two-thirds of the weight of the 
 metal taken. 
 
 3. IN THE WET WAY the calx of a metal may be obtained 
 by dissolving the metal in nitric acid, evaporating and igniting; 
 the residue is the calx. Such determinations have been made 
 by Berzelius (p. 22). Lead increased almost 8 per cent., mer- 
 cury fully as much, and copper 25 per cent. There can be no 
 doubt about the increase in weight in calcination. 
 
 4. Lead converted into nitrate gains 60 per cent. (19, 12). 
 
 Igniting the nitrate in a 
 tube, rutilant vapors first 
 appear in abundance, 
 then a colorless gas; a 
 shaving with but a single 
 glowing point, will burst 
 into flame when held in 
 this gas. Priestley made 
 this experiment 1772; 
 the gas he called “de- 
 phlogisticated air.” Its 
 main character is that 
 it SUPPORTS COMBUS- 
 TION. 
 
 5. Mercury heated for 
 a long time steadily to 
 near its boiling point is 
 slowly converted, espec- 
 ially on the surface, into 
 PRIESTLEY STATUE. a RED crystalline pow- 
 
 der, called “precipitate per se” also simply RED PRECIPI- 
 TATE. It is the calx of mercury. In the wet way it is pre- 
 pared much more rapidly, in the manner above stated (3). 
 
168 
 
 LECTURE 30. 
 
 . 6. Heating this red precipitate in a tube, it first turns dark 
 brown, then drops of metallic mercury appear on the cold parts 
 of the tube. At the same time a colorless gas is evolved, the 
 amount of which may be measured by our gas burette. 
 Tested as above stated, it supports combustion, or is dephlo- 
 gisticated air. Lavoisier, who made the same experiments 
 soon after, finally called this gas OXYGEN. Scheele had 
 called it fire air. 
 
 7. OXYGEN GAS, collected in the usual way, is shown to 
 be colorless, odorless, energetically supporting combustion; 
 it is slightly heavier than atmospheric air. 
 
 It was first liquefied in 1877, by Cailletet and Pictet; its 
 critical point is at 118 degs. below zero; 50 atmospheres pres- 
 sure liquefies it at that temperature. 
 
 8. Oxygen is most readily OBTAINED IN QUANTITY by 
 moderately heating^ the salt known as potassium chlorate, 
 which crystallizes in thin (oblique) rhombic tablets of 104.4 
 degs. This salt first fuses, then decomposes, often with ex- 
 plosive violence. When it is mixed with pulverized pyrolusite 
 (9, 7), the decomposition begins at a lower temperature and is 
 entirely safe and without violence. 
 
 9. COMBUSTIONS in oxygen gas are most beautiful and 
 instructive, if performed in combustion tubing of hard glass, 
 connected through the drying columns with the generator, and 
 on the other end with suitable absorption flasks for the pro- 
 ducts of combustion. Some of the substances to be burnt are 
 better placed in porcelain boats. This method of experimen- 
 tation is under perfect control of the operator, and much 
 more instructive to the student, than the common way witl4 
 large flasks. 
 
 10. CARBON (small prisms of blowpipe charcoal) burns 
 with a brilliant white light; the product is fixed air (16). 
 SULPHUR burns with a blue flame; the product is a gas,^ 
 bleaching blue litmus after having turned it red. PHOS- 
 PHORUS burns with flame, emitting a most dazzling white 
 
COMBUSTION AND OXYGEN. 
 
 109 
 
 light and giving a solid, white product of combustion, which 
 dissolves in water, to an acid (phosphoric). MAGNESIUM 
 and ZINC burn also with brilliancy — the first giving white, the 
 second green light. SODIUM burns with dazzling yellow light. 
 
 11. Several of these combustions can be shown to still 
 greater advantage by using the COMPOUND BLOWPIPE (5,9), 
 connecting the inner tube with the oxygen supply. STEEL 
 watch springs burn in this flame, producing a magnificent 
 shower of brilliant sparks of burning steel. PLATINUM wire 
 melts readily in this oxy-gas flame. LIME emits a most dazz- 
 ling white light when held in this flame; this is the so-called 
 calcium light. 
 
 12. Priestley discovered “ dephlogisticated air” 1774 
 
 in England. SCHEELE pro- 
 duced, entirely indepen- 
 dently, at about the same 
 time, his “fire-air” in 
 Sweden. Both remained 
 firm believers in the phlo- 
 giston theory, although 
 they had produced the 
 “eminently respirable gas” 
 of LAVOISIER, which he 
 afterwards called oxygen. 
 Too ofte*n, modern science 
 forgets this lesson ; thought 
 is as important as fact. 
 The old “ora et labora ” 
 
 scientists should read, “think and work.” 
 
 SCHEELE. 
 
 Notes 8. Oxygen gas need not be collected in bag or gasometer 
 beforehand; it may be generated while the experiments in combustion 
 (9) are exhibited to the class. , 
 
 In the DRY WAY, it is most elegantly generated by filling the mixture 
 of chlorate and pyrolusite (black oxide of manganese) in a combustion 
 
170 
 
 LECTURE 30. 
 
 tube and heating this in the combustion furnace. By properly regula- 
 ting the gas flames as to size and number^ the flow of oxygen can easily 
 be kept exactly as wanted. The gas should be dried in columns, and 
 passed through a little concentrated sulphuric acid in a wash bottle (with 
 straight safety tube) before it reaches the tube in which the combustion 
 is effected. The mixture should be dry, fill the entire length of the com- 
 bustion tube, but only about two thirds of its width. The heating should 
 begin nearest the drying columns. The total amount of oxygen for all 
 combustions is very small, when they are made as stated in the text, in 
 combustion tubing of about one inch diameter. Th6 wash bottle with 
 concentrated sulphuric acid is mainly inserted to show the rate at which 
 the gas flows. 
 
 In the WET WAY, oxygen is generated during my lectures exactly as 
 hydrogen. The Kipp is charged with lumps of pyrolusite and commer- 
 cial (lo volume) peroxide of hydrogen to which, cautiously and in small 
 doses, about one twelfth volume of concentrated sulphuric acid has been 
 added. This process is perfect; of course, the gas is rather expensive 
 when obtained in this way. It is readily understood that the volume, 
 is about twenty times that of the liquid reagent used. 
 
 The generating liquid must be drawn off at the close of the hour or 
 day; it deteriorates in keeping. 
 
 9. The combustion of the sodium is most brilliant and most conveni- 
 ently performed in an iron deflagrating spoon ; light the metal (thor- 
 oughly freed from the naphtha) by the flame of a Bunsen burner, then 
 direct a jet of oxygen gas upon it by means of a glass tube. For obvious 
 reasons it is advisable that the experimentator wear a mask or watch the 
 combustion through a pane of blue glass larger than the face. 
 
 The form of experimentation described in the books is much less 
 brilliant in results, comparatively clumsy and wasteful, and finally much 
 less instructive. 
 
 The sodium oxide produced contains enough peroxide to give the per- 
 oxide of hydrogen reactions when dissolved in water. 
 
 II. When time and means allow, the oxy-hydrogex blowpipe 
 should be used, and the most striking experiments indicated above, 
 should be repeated. In this case, the substances may be most conveni- 
 ently supported on charcoal or cupels, which again may stand on a Bat- 
 tersea scorifier supported on the ring stand. 
 
 29, 4. That Lavoisier is the Copernicus of Chemistry was first brought 
 out in the French Resume of my Atomechanik, 1867. 
 
31. OXIDE AND RADICAL. 
 
 1. The compounds which form when metals burn are now 
 understood to be OXIDES, consisting of the metal and oxygen. 
 All metallic calxes, made by heating the metal in air, must be 
 oxides; in other words, oxygen must be a constituent part of 
 atmospheric air. This was demonstrated by LAVOISIER, as 
 shall be shown in the next lecture (see Frontispiece). 
 
 2. The metallic calxes prepared in the wet way, being 
 identical with those obtained in the dry way, therefore also 
 are oxides. Accordingly, the determinations made by Berzelius 
 (30, 3) are really determinations of the equivalent of oxygen. 
 If mercury (equiv. 100) increases 8 per cent, the equivalent 
 of the oxygen is 8. Copper, having an equivalent of almost 
 32, increases 25 per cent., that is 8, which is the equivalent 
 of the substance combined with copper, or the oxygen. 
 
 3. SYNTHESIS OF WATER. Water, forming in the com- 
 bustion of hydrogen gas (17, 8), therefore is hydrogen oxide. 
 The exact proportions by weight of oxygen and hydrogen in 
 water were first determined in 1841 by DUMAS (p. 25). The 
 hydrogen was carefully purified and dried (17, 5), passed over' 
 copper oxide in a combustion TUBE resting on tiles barely 
 glowing red; water forms, condensing in the GLOBE to a 
 liquid; to avoid the escape of traces as vapor, the globe is 
 followed by a light absorption tube. The black copper oxide 
 is gradually turning red, being reduced to metallic copper. 
 
 4. This is not the place for a discussion of the details of 
 this determination of one of the fundamental data of chemical 
 science. Such a discussion the author has published, 1894, in 
 his True' Atomic Weights, pp. 176-183. The errors involved 
 in more recent determinations by chemists using more elabo- 
 rate and complex processes have also been indicated (pp. 
 185-189). 
 
172 
 
 LECTURE 31. 
 
 5. The weight of the combustion tube with copper oxide, 
 diminished by the weight of the same tubes at the close of the 
 operation, when the black oxide has been reduced to metallic 
 copper, evidently gives the weight of the oxygen consumed to 
 form the water. The weight of the water formed is the in- 
 crease in weight of the globe and absorption tube. In all 
 experiments the proportion of the weight of the oxygen to that 
 of the water is found as 8 to 9 exactly. Hence the hydrogen 
 used weighed one. Consequently, the equivalent of oxygen 
 is 8, exactly. 
 
 6. A CHEMICAL FORMULA (IN EQUIVALENTS) REPRE- 
 SENTS ONE EQUIVALENT OF THE COMPOUND BY THE 
 SYMBOLS OF THE EQUIVALENTS OF THE COMPONENTS. 
 The symbols, when representing an equivalent, we shall print 
 in italics. 
 
 Thus, the chemical formula of water is HO. This formula 
 expresses the simple FACT that one equivalent of hydrogen, 
 H—\^ and one equivalent of oxygen, C=8, are contained in 
 one equivalent of water HO=d, 
 
 7. DUMAS (p. 25) also established the true equivalent of 
 carbon, by burning a weighed amount of diamond in a current 
 of pure oxygen gas, and weighing the amount of fixed air pro- 
 duced, collected in strong potassium hydrate solution contained 
 in proper absorption tubes. The details are found in the 
 author’s True Atomic Weights, pp. 19-24, p. 147, and pp. 176- 
 177. The weight of the carbon burnt is to the oxygen taken 
 up as 3 to 8 exactly. 
 
 8. Accordingly, the equivalent of carbon in fixed air would 
 be 3, and the chemical formula of fixed air would be CO. 
 But Chemists have assumed for reasons that need not be 
 stated here, that there are two equivalents of oxygen ( = 16) in 
 fixed air to one of carbon. The experimental proportion of 8 
 to 3 then compels the adoption of 6 as the equivalent of carbon 
 and the formula of fixed air becomes CO^. For that reason 
 fixed air is commonly called CARBON DIOXIDE. 
 
OXIDE AND RADICAL. 
 
 173 
 
 9. We can now establish the composition of THE RADI- 
 CALS in carbonates and sulphates. The radical S^te (27, 9) 
 has the equivalent 48. Direct experiments have shown that 
 it contains but one equivalent of sulphur, 16; hence the 
 oxygen weighs 32, representing four equivalents. Conse- 
 quently the equivalent formula of the radical is O^S. 
 Sulphuric acid has the formula ^ O^S. The following formula 
 represents an equivalent each: Wa O^S. — Cu O^S. — 
 Pb O^S.— Ag O^S. 
 
 10. Direct experiments of this kind were made by v. 
 HAUER, 1857. Heating a weighed amount of cadmium sul- 
 phate in a current of dry hydrogen sulphide gas, he obtained 
 a residue of sulphide weighing 69.23 per cent, of the sulphate 
 taken. Nine careful determinations were made. Now, since 
 the equivalent of Cd is 56, that of S 16, Cd is 72, and 
 Cd O^S should be 104. But 72 is exactly 69.23 per cent, of 
 104. The formula of is therefore correct. 
 
 11. The radical of carbonates was found to have the 
 equivalent 30 (27, 10). It contains only one carbon, there- 
 fore three of oxygen, or C^te is O^C. 
 
 For magnesium carbonate Mg OgCthis gives 42. Ignition 
 leaves the oxide. Mg 0=20 or 47.62 per cent. Actual deter- 
 minations made by SCHEERER in 1850 on Magnesite from 
 Frankenstein gave 47.63 per cent., thus confirming the above. 
 
 12. For carbonates and sulphates the radicals are now 
 known. The third constituent has been found to be oxygen. 
 Its equivalent is 8, that of hydrogen being one. In carbon- 
 ates enter three equivalents of oxygen with the equivalent of 
 the metal and the carbon. In sulphates there are four equiva- 
 lents of oxygen. 
 
 The radicals of nitrates and muriates we must leave unde- 
 termined for a short time. 
 
32. ANALYSIS OF THE AIR. 
 
 1. The terraqueous globe is completely surrounded by the 
 air as by a mantle, protecting us equally agaist the cold of 
 cosmical space and the burning heat of the sun. In this air- 
 mantle float the clouds, the vapors sent up from the earth and 
 sea by the sunbeam ; they descend again as rain and snow. 
 Into this air- mantle passes dust and smoke from factory and 
 fire. Therefore, we call it with the Greeks, the ATMOS- 
 PHERE. 
 
 2. AQUEOUS VAPOR is present in the air in greatly vary- 
 ing proportions. We are sensitive to both an excessive 
 amount and to a deficiency thereof. Air at any given tem- 
 perature can contain a definite amount of vapor only; it then 
 is saturated, and a good HAIR HYDROMETER indicates 100 per 
 cent, moisture. During certain southwest winds in summer, 
 the humidity of the air may run down to less than 10 per cent; 
 moving air of this character (dry winds) scorches vegetation. 
 
 3. In these United States, about two hundred million tons 
 of coal — worth two hundred million dollars — are taken from 
 the mines and burnt every year (12.10), returning something 
 like 530 million tons of fixed air to our atmosphere, together 
 with smoke and ashes. Animal life, in the act of respiration, 
 also sends enormous quantities of fixed air into the atmos- 
 phere. Plants, we shall learn, take up this gas, decompose 
 it by the aid of the sunbeam, and thus maintain a sort of 
 equilibrium. 
 
 4. The chemical examination of atmospheric air must, 
 therefore, begin with the determination of the amounts of 
 moisture (water) and fixed air (carbon dioxide) present in 
 the same. Effective absorbents (17, 5, 6), contained in light 
 glass vessels of suitable form for accurate weighing, will re- 
 tain these separately. The increase in weight of these ves- 
 sels will tell the amount of water and carbon dioxide in the 
 volume of air that has passed through them. 
 
ANALYSIS OF THE AIR. 
 
 175 
 
 5. The simplest means of drawing air through a series of 
 vessels is by means of the ASPIRATOR. Any flask or jug 
 may be used as such, if closed with a doubly perforated stop- 
 per, provided with siphon, reaching to near the bottom of the 
 flask and lengthened by rubber tube outside, while the other 
 perforation by means of a short tube connects with the set of 
 absorption vessels. The volume of the water flown out is 
 equal to the volume of air drawn through. Special aspirator 
 flasks, with a lower side-tubulature, are in the market. 
 
 6. As a rule, the moisture is absorbed by fragments of 
 pumice, soaked with concentrated sulphuric acid, and kept in 
 so-called U-TUBES, now elegantly made with ground glass 
 stoppers and with short glass tubes for making connection. 
 The carbon dioxide is absorbed by a strong solution of caustic 
 potassa, contained in some of the varied forms of POTASSA 
 BULBS, first introduced by Liebig (p. 23). Further details 
 belong to practical chemistry. 
 
 7. Such determinations have shown that the amount of 
 water varies enormously, as was anticipated ; they have also 
 shown the entirely unexpected fact, that the amount of car- 
 bon dioxide varies but very little in the atmosphere. In round 
 numbers it amounts to three volumes in ten thousand volumes 
 of air. 
 
 8. Pure and dry atmospheric air can be obtained by draw- 
 ing common air through a set of absorption tubes of suitable 
 size, to the vessel where the air is to be used. See 17, 6. 
 If necessary to exclude all moisture and carbon dioxide, a 
 TEST SET of U and bulb tubes, inserted between the absorp- 
 tion columns and the receiver, must show no increase in weight. 
 
 9. If now a measured volume, say 100 cc, of such pure air 
 be slowly passed over pure copper gauze, heated to a low 
 redness in a combustion tube, connected with a strong glass 
 receiver, which as well as the tube with copper, was com- 
 pletely evacuated by a mercurial air pump, the copper will 
 turn black, combining with the oxygen of the air. The resi- 
 
176 
 
 LECTURE 32. 
 
 dual air measures 79 cc, so that 21 cc were oxygen. Dumas 
 (p. 25) and Boussingault. 
 
 10. This residual air is colorless and odorless; it does not 
 support combustion nor life. For the latter reason, Lavoisier 
 called it AZOTE and many French chemists continue to use 
 the symbol Az for this gas. We call it NITROGEN, and repre- 
 sent by the symbol N. Careful weighings have shown it to be 
 lighter than oxygen, in the proportion 7 to 8. Nitrogen has 
 been liquefied. Its critical temperature is — 146 degrees, its 
 critical pressure 35 atmospheres. 
 
 11. The first decisive demonstration of the composition of 
 atmospheric air was made by Lavoisier. Our frontispiece 
 pictorially commemorates this great event. Mercury was kept 
 near its boiling point for twelve days and nights continuously; 
 then the red precipitate first formed no longer showed increase, 
 nor the volume of air any decrease. 
 
 After cooling, the residual air measured 42 to 43 cubic 
 inches; originally 50 cubic inches had been taken. This 
 shows a reduction of about 15 per cent in the volume of air. 
 The residual air proved to be azote. 
 
 12. The red precipitate formed weighed 45 grains. Heated, 
 it left 41.5 grains of metallic mercury, yielding 7 to 8 cubic 
 inches of gas, proving to be oxygen. 
 
 When, in other experiments, the amount of oxygen so ex- 
 tracted by mercury and set free again from the red precipitate, 
 was mixed with the inert residual air (nitrogen), the gas 
 MIXTURE resulting was in every way identical with atmos- 
 pheric air. 
 
 This completed the analysis and synthesis of atmospheric air. 
 
 Note. The discovery of dephlogisticated air by Priestley gave 
 chemists a new gas of wonderful properties, only to involve chemical 
 processes into greater contusion and deeper mystery. The fire air, dis- 
 covered independently by Scheele, brought some light into the chem- 
 istry of the air, but most of the processes employed by him were so 
 indefinite as to make it difficult even to-day to express them in formulai. 
 
LAVOISIER. 
 
 1794 . 
 
ANALYSIS OF THE AIR. 
 
 177 
 
 It is, therefore, natural, that both Priestley and Scheele remained 
 faithful to the phlogiston theory, according to which metals lose some- 
 thing (phlogiston) when calcinated (dephlogisticated). 
 
 Lavoisier, the Copernicus of chemistry, pierced the veil of pheno- 
 mena that had hidden the truth to all previous investigators, lie had 
 only the same facts and materials which were also in the hands of the 
 English and Swedish chemists, who both were most eminent investiga- 
 tors of the empiric or purely experimental school. 
 
 Lavoisier as an experimentor was not superior to Priestley or Scheele. 
 It is true he possessed unlimited means to obtain all appliances he might 
 desire; but his brilliant discoveries, so far as apparatus was concerned, 
 might have been made equally as well by the poor apothecary of Koep- 
 ing. Surely, there never was a chemist who was so entirely independent 
 of pecuniary means as Scheele, whose very mind seemed to create all 
 the appliances he needed. Priestley also was very successful in doing 
 much with little. His own claims of having made his discoveries acci- 
 dentally, is one of the oddities of his character; for his writings bear 
 witness that he planned his experiments carefully. 
 
 Lavoisier was not a specialist; he was not merely an experimentor, for 
 he was also a profound thinker. His studies ranged from mathematics to 
 geology and physiology. He had mastered the fundamental and essential 
 parts of the science of his day, as did the great philosophers of old. To 
 this he added the Especial research in the more limited field of the 
 chemical processes. His mind directed the work of his fingers; and 
 when in this manner, any fold of the veil of appearances was displaced, 
 his mind was able to read the new form in accordance with the eternal 
 ideal. 
 
 In this way the material gathered by the skillful workmen anywhere, 
 in England or in Sweden, were refined and perfected in his hand and 
 placed by his mind in harmony with the universal laws of nature, suffi- 
 ciently so to find the eye point of the grand perspective; and so a revo- 
 lution in chemistry was accomplished, exactly corresponding to that 
 effected by Copernicus in astronomy two and a half centuries earlier. 
 
 The sun and the stars move around the earth, resting in the center of 
 the world ; so the senses declared before Copernicus, so they do to us. 
 But Copernicus mentally placing his eye in the sun, saw clearly the true 
 system of the w’orld, and we now understand the mocking of our senses. 
 
 In a fire, the wood is consumed, the flame seems but a part of the 
 wood, and the ashes are all the rest, so testifies our bodily eye. The 
 same general relation Stahl declared to be true for the metals; they con- 
 sist of the calx and phlogiston. But the mental eye of Lavoisier^ saw 
 the calx result from a union of the metal with a spirit invisible to the 
 bodily eye, but sensible to the pointer of the balance. He isolated a 
 portion of the matter, made it complete an entire metamorphosis by 
 synthesis and analysis — and the vision appearing to his mind had become 
 the starting point for the work of a century. 
 
33. NITROGEN, PHOSPHORUS # ARGON. 
 
 1. The alchemists, in their search for the elixir, subjected 
 all kinds of animal materials to their operations. Brand, at 
 Hamburg, in 1669, while doing such work, produced the true 
 phosphorus. This discovery created the greatest sensation at 
 the time. Having concentrated urine by freezing or by evapo- 
 ration, he distilled the residue, mixed with sand and charcoal 
 dust, gradually increasing the temperature. Now phosphorus 
 is extracted from bones. 
 
 2. PHOSPHORUS is a soft, colorless (or faintly yellow) 
 solid, of a specific odor. G 1.83, F 44 degrees, B 278. It is 
 exceedingly combustible and readily inflammable; it must be 
 handled with great care and is kept under water. Exposed to 
 the air, it shows a glow of light in the dark, whence its name 
 (light-bearer). It burns with extreme brilliancy in oxygen,- 
 giving solid, white phosphoric oxide, which dissolves in water 
 to phosphoric acid (30, 10). 
 
 3. The great combustibility of phosphorus permits an 
 approximate analysis of atmospheric air to be made as lecture 
 experiment. In a pneumatic trough is placed a tripod support- 
 ing a scorifier on which is placed a coupel with a well dried 
 piece of phosphorus. An open, well dried, bell glass is set 
 over the tripod, and resting on three pieces of lead. The 
 water should be at least three inches below the scorifier. 
 
 4. The phosphorus is ignited by touching it with the heated 
 end of a wire, when promptly the bell glass is stoppered. The 
 burning phosphorus fills the glass with a cloud of white oxide 
 so dense, that no outline of the objects inside can be dis- 
 tinguished. The surface of the water is first depressed (due 
 to expansion) but soon begins to rise, marking the consump- 
 tion of the oxygen. 
 
 5. The combustion ceases. The white cloud gradually dis- 
 appears, the oxide being dissolved in the water to phosphoric 
 
NITROGEN, PHOSPHORUS AND ARGON. 
 
 179 
 
 acid — indicated by the blue litmus, that had been added to the 
 water, changing to red. When no further change in the level 
 of the water takes place, the water inside will be seen to occupy 
 about one -fifth of the volume originally occupied by air. 
 
 6. To examine the character of the residual air, fill the 
 trough suificiently so that the level outside again stands even 
 with the level inside the bell glass. Then remove the stopper 
 to introduce the various tests, such as a burning wax taper, 
 which will be extinguished. The apparatus being promptly 
 stoppered after each test, can be left on the table till the 
 next day. Then filling with oxygen equal to the original 
 volume, and after equallizing level of water, the air will' 
 soon show the properties of atmospheric air. All the essential 
 features of the subject will be recognized in this form of 
 experiment, which is perfectly safe. 
 
 7. In the wet way, pyrogallic acid quite promptly absorbs 
 oxygen from the air, if an excess of caustic alkali be present; 
 the reagent turns deep brown. This method, due to Liebig 
 (p. 23), is very quick and sufficiently exact. It can be used 
 over mercury or with a gas burette, connected with an absorp- 
 tion gas pipette. 
 
 8. A shower of electric sparks, passed through atmospheric 
 air, near the surface of water (or better, a solution of caustic 
 potassa) soon reduces the volume considerably. If the water 
 was tinted with cochineal, it will show acid reaction. From 
 the alkaline solution nitre can be obtained. Nitric acid has 
 evidently been produced. This accounts for the presence 
 of nitric acid in rain water during thunderstorms. 
 
 9. Cavendish, who first made this synthesis of nitric acid 
 from atmospheric air and water, added pure oxygen whenever 
 the volume diminished no longer. But he found it impossible 
 to convert the entire volume of air into acid ; about one per 
 cent, of the original volume remained. 
 
 10. These remarkable results of Cavendish were over- 
 looked an entire century, till Lord RALEIGH, by another 
 
180 
 
 LECTURE 34. 
 
 method, obtained the same non -absorbable residual volume of 
 nitrogen. He calls this gas ARGON. The density of argon 
 exceeds that of nitrogen 50 per cent. 
 
 11. When absolutely dry nitrogen gas, entirely free from 
 oxygen, is passed over magnesium heated to barely beginning 
 redness in the tube of a combustion furnace, the nitrogen 
 combines with the metal. The magnesium nitride formed is a 
 brownish solid. 
 
 This property of magnesium has recently become very use- 
 ful for the extraction of argon from atmospheric air. 
 
 12. When magnesium nitride is moistened, the odor of 
 ammonia is produced. Mg and H Hate give H (am- 
 monia) and insoluble Mg Hate, a mixture of hydrogen and 
 nitrogen gas, in the presence of an acid, exposed to a shower 
 of electric sparks, gives the ammonium salt of that acid. 
 This reaction corresponds exactly to that of Cavendish (9). 
 
 34. BATTERY AND DYNAMO. 
 
 1. The chemist of the present has two physical powers at 
 his service, namely HEAT AND ELECTRICITY. The chemist 
 of antiquity only possessed the first, and that in but the nar- 
 row limits from the freezing of water to a white heat. To-day, 
 the chemist employs temperatures from the freezing point of 
 oxygen to the boiling point of carbon, and uses electricity at 
 his pleasure. 
 
 2. The application of electricity in the chemical arts dates 
 from the beginning of this century, when VOLTA (p. 31) con- 
 structed the galvanic BATTERY, the Voltaic pile. In the great 
 chemical industries, electricity could not be used until the 
 DYNAMO had cheapened and enlarged its flow by drawing it 
 from a common coal fire and from cataracts. 
 
BATTERY AND DYNAMO. 
 
 181 
 
 3. The voltaic pile consisted of pairs of plates of copper 
 and zinc, separated by a moistened rag (1800). Soon the 
 plates were enlarged and each pair placed in a distinct vessel, 
 containing water; such single CELLS united constitute the 
 BATTERY. Water being replaced by salt solution or by dilute 
 acid, increased the power greatly, but shortened its duration. 
 Most of the zinc was wasted, being consumed without pro- 
 ducing electricity. 
 
 4. Zinc in dilute acid dissolves with evolution of hydrogen. 
 Pour a little mercury into the vessel, and the evolution stops, 
 the zinc having become amalgamated, or coated with mercury 
 on its surface, and mercury is insoluble in dilute acid. Pour 
 some of the acid on platinum foil in another tube — no solution 
 will take place, no effervescence will be seen, for platinum 
 requires even aqua regia for its solution. 
 
 5. But pour the balance of the first glass on this platinum, 
 so that the amalgamated zinc rests upon, or at least touches 
 the platinum foil ; instantly the evolution of hydrogen will 
 begin again and be more abundant than with the zinc alone. 
 Furthermore, the hydrogen does no longer seem to rise from 
 the zinc, but from the insoluble platinum. This continues 
 till the zinc or the acid is consumed. 
 
 6. Both the amalgamated zinc and the platinum, taken 
 separately, are insoluble in the dilute acid. Even simply lift- 
 ing the platinum up in the acid, so that the platinum no longer 
 touches the amalgamated zinc, stops the evolution of gas com- 
 pletely. The amalgamated zinc IN CONTACT with the plati- 
 num is soluble in dilute acid, when not in such contact it is 
 insoluble. 
 
 7. Such an action is called galvanic; it involves the pro- 
 duction of an electrical contrast between the two metals, the 
 amalgamated zinc and the platinum. Accordingly, in a gal- 
 vanic cell, if the zinc is not to be wasted, but only to be used 
 for the production of the current, the zinc must be thoroughly 
 
182 
 
 LECTURE 34. 
 
 amalgamated. In that case it can dissolve only while the 
 contact is produced by closing the circuit. 
 
 8. But even such a cell is not constant yet. The other 
 plate — copper — is seen to become coated. Daniell prevented 
 this by placing the copper in a solution of blue vitriol, when 
 pure copper deposited while the current is used. The simplest 
 construction of this kind we have in the GRAVITY CELLS — 
 copper plate in heavy blue vitriol solution below, the zinc plate 
 in lighter dilute acid above. 
 
 9. The most effective cells yet constructed, are those of 
 Grove and Bunsen in which copper is replaced by platinum 
 (Grove) or carbon (Bunsen, p. 24), and kept pure by being 
 inserted in concentrated nitric acid. As this acid would 
 rapidly dissolve the amalgamated zinc, the nitric acid with the 
 Pt or C is contained in a POROUS CUP, which again is set in 
 the dilute acid contained in the glazed cup holding the zinc. 
 
 10. When such a cell is closed — that is, the carbon united 
 with the zinc by a copper wire (conductor), the chemical 
 action sets in, and an electric, or rather galvanic current flows 
 through the wire — the circuit. Zinc dissolves as zinc sulphate 
 in the outer cup, THE HYDROGEN PASSES THROUGH THE 
 DILUTE ACID AND THE POROUS CUP, to be oxidized to 
 water when it reaches the concentrated nitric acid. This is 
 also evidenced by the rutilant vapors and red to green colora- 
 tion of the acid. The acid gradually becomes dilute, but the 
 carbon remains free from gas. THE CELL IS CONSTANT. 
 
 11. That a galvanic CURRENT passes through a closed 
 circuit is readily shown by the production of heat and magnet- 
 ism in the circuit. The first, by inserting a thin iron or 
 platinum wire, gradually shortening it, till it glows red hot, 
 white hot and finally melts. The second, by winding the 
 circuit wire around soft iron, which becomes a temporary 
 magnet while the circuit is closed — an electro-magnet. 
 
 12. With such electro-magnets, powerful machines are 
 constructed, the so-called electric MOTORS, seen on our street 
 
BATTERY AND DYNAMO. 
 
 183 
 
 railways and in our shops. The best of these are REVERSI- 
 BLE, that is, if moved by any mechanical power (steam, 
 hydraulic turbine) the motor produces electricity; it is then 
 called a DYNAMO. These furnish the electricity required in 
 modern chemical works. 
 
 Notes. Four Bunsen cells joined in series, answer for all necessary 
 experiments. The hydrogen current going in each cell from the zinc 
 through the liquid to the other solid (C, Pt, Cu in the different kind of 
 cells) the galvanic current is considered to flow in the same direction, so 
 that the exposed carbon (or Pt, Cu) is considered the positive pole of 
 each cell, and the zixc the negative pole. Copper wires (best insu- 
 lated) attached, carry the electrical power of these poles as good conduc- 
 tors; when these two wires are brought into metallic contact, direct or 
 through any special apparatus, the circuit is said to be closed, the cur- 
 rent will pass and do its work. 
 
 Attach a file to one of these wires, and draw the other wire along the 
 file; a shower of sparks of burning steel will be seen, especially brilliant 
 if a thick wire coil be inserted. The production of heat, magnetism and 
 motion has been referred to in the text proper. 
 
 For some purposes, the current is intensified by induction. A pri- 
 mary COIL of heavy wire is introduced in the circuit, which is automati- 
 cally broken and closed in rapid succession by an iron armature attached 
 to a spring. A very long and very thin copper wire, thoroughly insula- 
 ted, forms an outer secondary coil around the first coil. Connecting 
 the terminals of this secondary coil with tubes containing various gases 
 under low pressure, they will be illuminated by the discharge .(Geisler’s 
 and Plucker’s Tubes). Even a shower of sparks will pass through air 
 between balls or wires brought into proper distance, when connected 
 with the terminals. Electricity thus produced in a near conductor, not 
 in metallic contact with the primary conductor, is considered produced 
 by induction. Coils of this kind are called induction coils. The 
 forms devised by Ruhmkorff are the best. 
 
 The great subject of electric induction was mainly established by the 
 researches of Faraday (p. 26) at the Royal Institution of Great Britain, 
 from 1820 to 1850. The methods found application on a large scale 
 when Siemens and Gramme devised practical methods of winding arma- 
 tures. Great electric motors and dynamos finally were constructed 
 since 1870. In these powerful machines, electric engineering applies 
 the electrical science qX Oersted, Ampere and Faraday, and permits the 
 economic transmission of power over a single wire to great distances. 
 
35. QUALITATIVE ELECTROLYSIS. 
 
 1. Within a month after Volta had, by letter to the presi- 
 dent of the Royal Society of London, described his fertile 
 invention, two English chemists, Nicholson and Carlisle, suc- 
 ceeded in decomposing water by the current of the voltaic 
 pile. This was the first step into ELECTRO-CHEMISTRY. 
 
 2. The Hofmann (p. 34) DECOMPOSING CELL in use at 
 lectures consists of three communicating vertical tubes. The 
 middle one has a globular reservoir at the top. The two late- 
 ral tubes are provided with a glass stop -cock at the top and 
 with platinum ELECTRODES near the lower part. These 
 electrodes consist of a rectangular piece of platinum foil, sol- 
 dered to a platinum wire, which is fused through the glass. 
 
 3. When the apparatus is filled with dilute sulphuric acid 
 — pure water is not a conductor — and the electrodes are con- 
 nected with the conducting copper wires leading to the poles of 
 the battery, bubbles of gas form immediately and rise to the 
 top in a constant stream. The volume of the one gas is seen 
 to be twice that of the other. 
 
 4. Very carefully opening the stop-cock over the larger 
 volume, the issuing gas can be lit; it burns with a pale, hot 
 flame; it is hydrogen. The other gas rekindles a glowing 
 shaving; it is oxygen. Careful experiments have shown that 
 none of the acid disappears. Accordingly, the galvanic cur- 
 rent has decomposed water into its constituents, oxygen and 
 hydrogen. Their ratio of volume is seen to be one to two. 
 
 5. Tracing the connections made by wire between the 
 poles of the battery and the electrodes, it is readily seen that 
 the current of hydrogen in the decomposing cell flows in the 
 same direction as in the battery, namely from the zinc through 
 the acid to the other solid in each battery cell. This is also 
 the direction assumed by physicists for the current of positive 
 electricity. 
 
QUALITATIVE ELECTROLYSIS. 
 
 185 
 
 G. Accordingly, the entire circuit, comprising all the cells 
 of the battery, the connecting metallic conductors and the de- 
 composing cell, is pervaded by one continuous electric current 
 flowing in the same direction. Produced in the battery cells 
 by chemical action, directed from the zinc to the carbon, it 
 flows in the same direction through the wire to the decompos- 
 ing cell, accomplishes its chemical work and continues to its 
 origin. Breaking the circuit at any point, the entire current 
 stops throughout. 
 
 7. Before we can go on with this subject, we must make 
 ourselves familiar with the necessary terms in use. The 
 last carbon of the battery is called its POSITIVE POLE; the 
 wire conductor connecting it with one of the plates of the 
 decomposing cell makes this plate the POSITIVE ELECTRODE. 
 The other pole and electrode are called the NEGATIVE. Now, 
 bodies charged with unlike electricities attract each other, but 
 when charged with like electricities they repel each other. 
 Supposing the hydrogen drawn to the negative electrode, or 
 pushed from the positive electrode, it has been thought to be 
 or have been charged with positive electricity. At any rate, 
 a substance appearing, like hydrogen, at the negative electrode, 
 is CALLED THE ELECTRO-POSITIVE CONSTITUENT of the 
 substance decomposed. See black-board diagrams. 
 
 8. The chemical decomposition effected by the galvanic cur- 
 rent is called ELECTROLYSIS. The substance decomposed 
 is called the ELECTROLYTE. The constituents collecting at 
 the electrodes are called the IONS. Faraday called the 
 electro positive ion, collecting at the negative electrode or 
 CATHODE the cathion. The electro -negative constituent 
 appearing at the positive electrode or ANODE, he called the 
 anion. 
 
 9. For more careful experiments on electrolysis -attended 
 with the evolution of gases, it is advisable to use simple gas- 
 collecting electrodes of the following form. The platinum 
 wire is fused into a glass tube by means of which it is 
 
186 
 
 LECTURE 35. 
 
 fastened in a good cork or rubber stopper. This stopper also 
 is provided with a small tube, connected with rubber to carry 
 the gas to a gas burette or the pneumatic trough. The stop- 
 per is inserted in a suitable tube, placed into the electrolyte 
 of a stand cylinder. If two such collectors are used, both 
 gases can be collected separately. 
 
 10. If only liquids or solids are to be collected, a U-tube 
 answers as decomposing cell, and platinum electrodes can be 
 inserted from the top. 
 
 Using a blue vitriol solution, copper deposits as the negative 
 electrode (the cathode). Make this the anode (positive 
 electrode) and the copper dissolves again. ■ Thus copper — and 
 other metals — are the electro -positive constituent of metallic 
 salts, and metals are dissolved at the positive electrode. 
 
 11. The solution of a neutral salt, like potassium sulphate, 
 tinged ruby-red with cochineal, subjected to electrolysis in a 
 U-tube cell, promptly shows a purple tint at the negative and 
 an orange tint at the positive electrode. Consequently the 
 acid is the electro -negative constituent of neutral salts, while 
 the hydrate is the electro -positive constituent thereof. 
 
 12. Accordingly, SALTS ARE REALLY DUAL COM- 
 POUNDS, as first concluded from the solution of the metals in 
 acids, and as it is expressed in the chemical names of salts 
 (for example, copper sulphate). 
 
 The electro-positive constituent (cathion), appearing at the 
 negative electrode (cathode) is hydrogen, metal or base. 
 
 The electro- negative constituent (anion), appearing at the 
 positive electrode (anode) is oxygen, the acid radical or acid. 
 
 By secondary (simple chemical) reaction, the radical with 
 water gives oxygen set free and the acid. Thus Cu S^te gives 
 a deposit of Cu on the negative electrode, while the radical 
 S^te, appearing at the positive electrode, must decompose the 
 water, uniting with H to form the acid H setting free 
 
 the O gas. . 
 
36. APPLIED ELECTROLYSIS. 
 
 1. The synopsis of facts presented in the preceding two 
 lectures barely indicates the importance of the galvanic current 
 to chemistry. In this lecture a few of the most instructive 
 special scientific and technical applications of electrolysis will 
 be added from the great number already in common use, and 
 often grouped in special treatises on Electro-Chemistry. 
 
 2. Lavoisier had recognized lime, magnesia, potassa and 
 
 soda as bodies chemically 
 resembling metallic calxes. 
 Chemists had accordingly 
 tried to produce such metals 
 from them. Subjecting solid 
 caustic potassa to electroly- 
 sis, HUMPHRY DAVY, at 
 the Royal Institution, no- 
 ticed the separation of min- 
 ute white, metallic globules, 
 burning almost as soon as 
 formed. Thus the light 
 metals (Ka, Na, Mg, Ca, 
 Sr, Ba, etc.,) were first 
 produced in 1807. 
 
 3. The finely pulverized mineral fluorite (11, 10) treated 
 with rather concentrated sulphuric acid in a covered dish of 
 lead gives a most poisonous gas, which is an acid and has the 
 special property of dissolving silica. It is used to etch glass 
 where not protected by a film of wax. The supposed non- 
 metallic or electro- negative constituent of this acid was called 
 FLOURINE after the mineral, which itself, was called calcium 
 fluoride, .while the acid was called hydrogen fluoride. 
 
 4. All attempts to produce this hypothetic substance fluor- 
 ine failed until 1886, when MOISSAN (p. 36) at the School of 
 Pharmacy of Paris, succeeded in isolating and confining this 
 
 HUMPHRY DAVY. 
 
188 
 
 LECTURE 36. 
 
 the most active of all substances. He obtained it by the elec- 
 trolysis of the absolute (anhydrous) acid, in which anhydrous 
 potassium fluoride had been dissolved to make the liquid a 
 conductor. The decomposing cell had to be made of platinum, 
 closed by stoppers of transparent fluorspar. The liquid was 
 cooled to 50 below freezing. 
 
 5. FLUORINE appeared as a greenish yellow gas; liquefy- 
 ing at 95 degs. below freezing. It combines with mercury at 
 common temperatures, and with iron or even platinum at a 
 moderate heat. Iodine, sulphur, phosphorus, arsenic and car- 
 bon burst into flame in fluorine. Hydrogen and fluorine unite 
 even in the.dark with explosion. Fluorine decomposes water 
 instantly, giving ozone and hydrofluoric acid. Hence the 
 necessity of removing all traces of water to isolate fluorine. 
 
 6. Fluorine is the most strongly electro- negative substance 
 known, precisely as potassium is the most electro-positive. 
 Both have been first produced by electrolysis. Both decom- 
 pose water at common temperatures. The metal potassium 
 takes the place of the hydrogen, while the non-metal fluorine 
 takes the place of the oxygen, by substitution. 
 
 7. While the isolation of fluorine cannot be exhibited to a 
 class, it is very irrstructive to prepare and exhibit the corres- 
 ponding non -metallic constituent of muriatic acid. The two 
 cases are every way parallel. The liquid used is a saturated 
 solution of salt with one -tenth its volume of concentrated 
 muriatic acid. Electrodes of carbon have to be used, this gas 
 readily attacking platinum at common temperatures. 
 
 8. The poisonous gas must be confined in a series of 
 absorption flasks, Drechslers and columns. To avoid any gas 
 escaping into the air, the last column should be charged with 
 pumice wet with a strong solution of caustic potash. In a dish, 
 aqua ammonia should be handy to remove the gas that may 
 escape when substances are introduced into the glass vessels. 
 
 9. The gas produced at the positive electrode is yellowish 
 green — hence it has been called CHLORINE by Davy, 1810. 
 
APPLIED ELECTROLYSIS. 
 
 189 
 
 It bleaches and destroys organic colors; it explodes with 
 hydrogen; pulverized metallic antimony thrown into a cylinder 
 with chlorine burns brightly. Potassium bursts into flame in 
 chlorine. Its tendency to combine with hydrogen makes it 
 destructive to organic tissue. 
 
 Chlorine is largely absorbed by water, forming chlorine 
 water. This possesses the bleaching effects of the gas, and 
 dissolves even gold and platinum in the cold to chlorides 
 (19, 5). 
 
 10. Scheele first produced this gas (1774) by warming 
 pyrolusite (9.7) with muriatic acid; he called it PHLOGISTI- 
 CATED MURIATIC ACID. When oxygen had been recognized, 
 Berthollet called it OXYGENATED MURIATIC ACID (1785). 
 Lavoisier had supposed oxygen to be essential to all acids, as 
 implied by the name: acid producer. Davy proved (1808) 
 that muriatic acid contains no oxygen, but consists of the two 
 substances hydrogen and CHLORINE only. Consequently 
 MURIATES ARE CHLORIDES; and the equivalent of chlorine 
 therefore is 35.5. See 27, 10. 
 
 11. By the method of Scheele, chlorine gas is produced on 
 a large scale. Absorbed by lime and dilute cold alkalies, the 
 so-called HYPOCHLORITES result (Ca, bleaching powder ; Ka, 
 eau de Javelle; Na, Labarraque’s liquid). These are effective 
 bleaching and disinfecting compounds. A warm concentrated 
 solution of caustic potassa yields crystals of POTASSIUM 
 CHLORATE (30, 8). The residue left after heating this 
 salt to obtain oxygen, crystallizes in cubes from its solution; 
 it is POTASSIUM CHLORIDE. — These compounds can all be 
 obtained by the electrolysis of potassium chloride. 
 
 12. Electrolysis has long been applied in the arts for elec- 
 troplating (gold, silver), electrotyping (Cu) and even in the 
 metallurgy of copper and gold. Since the dynamo furnishes a 
 cheap and powerful electrical current, chemical manufacturing 
 is changing to a considerable extent, by the substitution of 
 electrolytical for purely chemical processes. We shall come 
 back to this subject later on. 
 
37. EQUIVALENT AND ELECTRICITY. 
 
 1. In electrolysis we have a decomposition of a compound 
 into its constituents without the addition of special reagents, 
 excepting the presence of a volatile acid or the results of 
 secondary reactions. Accordingly, electrolysis may be ex- 
 pected to furnish QUANTITATIVE METHODS OF HIGH PRE- 
 CISION for the determination of many substances. Experience 
 has fully confirmed this expectation. 
 
 2. Not only the most accurate, but at the same time the 
 most RAPID DETERMINATION of nearly all metals, is effected 
 by electrolysis. The substance is weighed in a PLATINUM 
 DISH and dissolved therein. The dish is made the negative 
 electrode, and the current kept up till no longer a trace of the 
 metal can be detected in a drop of the solution. Then the 
 solution is poured off, the metal generally adhering to the dish, 
 is washed with water, then with alcohol ; finally it is dried 
 and weighed, still on the dish. 
 
 3. NO TRANSFERS having been made, a number of serious 
 errors affecting all other analytical processes, are avoided in 
 electrolysis. The solutions most serviceable are nitrates, 
 sulphates and cyanides, exemplified in silver, copper and gold 
 determinations. The degree of temperature, and the density 
 of the current (amount per square centimeter of negative 
 electrode) are of influence on the results. 
 
 4. Even if more than one metal be present, electrolytic 
 determinations of each, in the same sample, are generally 
 possible ; for the tension required for the separation of metals 
 in electrolysis varies considerably, and the acid or solvent 
 used is of great influence. Thus copper is deposited by much 
 less electrical tension than nickel. The investigations of 
 Professor Edgar F. Smith, of Philadelphia, have been success- 
 fully centered on this practically important field ; his special 
 methods are advantageously followed in the laboratories. 
 
 5. STRIKING EFFECTS OF GALVANIC ACTION, have, 
 however, long been used IN QUALITATIVE ANALYSIS. Thus, 
 
EQUIVALENT AND ELECTRICITY. 
 
 191 
 
 metallic zinc reduces all the metals of the arsenic group; anti- 
 mony and tin separate often in crystal form, arsenic largely 
 escapes as gaseous hydrides, if sulphuric acid is used. The 
 solutions are supposed to be contained in a watch glass, to 
 permit examination by magnifier or microscope. 
 
 But if instead of a watch glass, the cover of a platinum 
 crucible be used to contain the acidfied liquid, galvanic action 
 sets in. The current in the cell will go from the zinc through 
 the acid to the platinum; hence the bubbles of hydrogen gas 
 will appear at the platinum only. If antimony, even a bare 
 trace, be present, it will go with the current, STAINING THE 
 PLATINUM BLACK (or brown if exceedingly little be present). 
 Neither tin nor arsenic stains the platinum. The tin deposits 
 on the zinc. The arsenic largely escapes, as stated. 
 
 6. By connecting a pair of gas-collecting electrodes (35, 9) 
 each with a gas burette, while* the electrodes are placed in 
 water, acidified with sulphuric acid, the hydrogen and oxygen 
 gas can be most accurately measured. The volume of the 
 hydrogen will, at every instant, be twice that of the oxygen. 
 But direct weighings have shown oxygen to weigh 16 times as 
 much as an equal volume of hydrogen (3, 12). Hence the 
 weights obtained are as 16 to 2 or 8 to 1. Electrolysis gives 
 the equivalent of oxygen 8, as found before by direct chemical 
 means (31, 3-5). 
 
 7. If a strong current is used, the volume of oxygen gas 
 possesses a marked odor and is less than half that of hydrogen. 
 It has been found, that a portion of the oxygen has been con- 
 densed, its density being increased 50 per cent. This con- 
 densed oxygen is called OZONE. It is very much more active 
 than ordinary oxygen. It decomposes potassium iodide, which 
 oxygen does not do. 
 
 For these reasons it is best to measure the hydrogen only 
 for quantitative purposes. 
 
 8. Since the hydrogen passes over continuously, its volume 
 at any given time is a measure of the total electrical current 
 used up to that time. Instruments for the measurement of 
 
192 
 
 LECTURE 37. 
 
 the galvanic current by the chemical effect produced are called 
 VOLTAMETERS. The unit used is called the Ampere; it 
 corresponds to 6 mgr. hydrogen in ten minutes time, or to 7.2 
 cc hydrogen gas per minute at common temperatures and 
 pressure (i. e. when one mgr-Mg yields one cc hydro- 
 gen gas). . 
 
 9. If a number of decomposing cells of the same kind, say 
 charged with the same acidified water, be inserted in series in 
 the same circuit, the electrolysis in all will not only be the 
 same in kind or quality, but also the same in amount quanti- 
 tatively. This equality remains, independent of any difference 
 in form, magnitude or character of the different decomposing 
 cells, placed in the same circuit. This proves, that THE IN- 
 TENSITY OF A GALVANIC CURRENT IS THE SAME AT ALL 
 POINTS OF THE CIRCUIT. This fact is really assumed in 
 the use of the voltameter. 
 
 10. If the different cells, inserted in series in the same 
 circuit, contain different compounds, the ELECTROLYSIS 
 SEPARATES CHEMICALLY EQUIVALENT AMOUNTS IN THE 
 DIFFERENT CELLS in the same time. Thus, acidified water, 
 a copper solution, and a silver solution, connected in continu- 
 ous series, yield qualitatively, at the negative electrodes, 
 the positive constituents: hydrogen, copper and silver. Re- 
 ducing the volume of hydrogen to weight, the proportions 
 are invariably as 1 : 31.75 : 108, that is, as the equiva- 
 lents of H, Cu, Ag. This is the electrolytic law of Faraday 
 (p. 26). 
 
 11. A mercurous and a mercuric solution, placed in the 
 same circuit, yield double the weight of mercury in the first. 
 The equivalent of mercury in mercuric compounds has been 
 found to be 100; in mercurous it is therefore 200. In a like 
 manner, the equivalent of iron, in ferrous solutions, is known 
 to be 28 (18, 10) ; but in feric solutions, it is only two-thirds 
 thereof, or 18.66. The symbol for the — ous compounds has 
 frequently been distinguished by small initial, thus hg 200, 
 fe 18.66. 
 
EQUIVALENT AND ELECTRICITY. 
 
 193 
 
 12. In this manner, the ELECTROLYTIC EQUIVALENT of 
 many substances has already been determined by Faraday 
 (1834) ; the value found was always the same as the CHEMI- 
 CAL EQUIVALENT determined by chemists without use of 
 electricity. Consequently, electrolysis takes place according 
 to the proportions of the chemical equivalents. This is the 
 LAW OF FARADAY. Fusible substances were also decom- 
 posed in the dry way, keeping them liquid by fusion. This 
 avoids all secondary reactions caused by the presence of 
 water (35, 12). 
 
 38. EQUIVALENT AND VOLUME. 
 
 1. Electrolysis shows that water contains two volumes of 
 hydrogen gas for every one volume of oxygen gas (35, 3, 4). 
 Evidently we may consider the two volumes of hydrogen gas 
 chemically equivalent to one VOLUME of oxygen gas, precise- 
 ly as we have called the corresponding WEIGHT one of hydro- 
 gen, chemically equivalent to the weight eight of oxygen. 
 
 2. But in doing so we would use the same term equivalent 
 for relations of WEIGHT and of MEASURE (or volume). This 
 slight imperfection of expression has been avoided, by speak- 
 ing of volumes as HAVING A VALENCE (worth), while 
 weights continue to be spoken of as BEING EQUIVALENT. 
 Thus chemists say: 8 mgr. oxygen are equivalent to 1 mgr. 
 hydrogen; and also: one volume of oxygen gas has the 
 valence of two volumes of hydrogen gas. 
 
 3. If we adopt, for gases, the measure or volume as unit, 
 and represent ONE volume by ONE symbol in roman type, 
 (to distinguish it from the equivalent weights printed in 
 italics), then the VOLUME FORMULA of water evidently 
 becomes H 2 O. 
 
 The equivalent formula HO is no less true, for it refers to 
 equivalent WEIGHTS. Both formulae express FACTS well 
 
194 
 
 LECTURE 38. 
 
 determined; in one case, they relate to weight, in the other, 
 to gas measure (volume). 
 
 4. In the electrolysis of MURIATIC ACID, the gases pro- 
 duced can also readily be measured by our gas burette; we 
 need only interpose our air lock, or any dry cylinder contain- 
 ing atmospheric air, between the decomposing cell and the 
 burette. The chlorine will push the air into the burette, but 
 not itself come in contact with the water. — The experiment 
 shows the volume of the chlorine to be equal to that of the 
 hydrogen. Chlorine therefore has the valence one. The 
 volume formula of hydrogen chloride is H C 1, the same as its 
 equivalent formula, H C I , — After each experiment, the air 
 lock must be properly ventilated. 
 
 5. AQUA AMMONIA can also be electrolysed. Most suitable 
 is a concentrated solution of salt, to which not more than 
 one -tenth its own volume of the strongest aqua ammonia has 
 been added. Hydrogen will appear at the negative electrode, 
 nitrogen at the positive electrode. The volume of hydrogen is 
 exactly three times that of the nitrogen. That is, the valence 
 of nitrogen is three, or one volume of nitrogen is equivalent to 
 three volumes of hydrogen. The volume formula of ammonia 
 is therefore H 3 N. Its equivalent formula is HN, 
 
 6 . The equivalent of nitrogen, by weight, has been found 
 to be 4|. That is, the weight of three volumes of hydrogen 
 is to that of one volume of nitrogen as 1 to 4|. Consequently, 
 the weight of one volume of hydrogen is to that of one volume 
 of nitrogen, as ^ to 4|, or as 1 to 14. If the weight of one 
 volume of hydrogen be taken as unit, one volume of nitrogen 
 should weigh 14 such units. Actual experiments have shown 
 such to be the case (3, 12). 
 
 7. It is true, all determinations made prior to 1895, gave 
 14.04; but as Lord Rayleigh has shown, this was due to the 
 fact, that the presence of the heavier argon in the nitrogen 
 had been overlooked (33.10). When making weighings with 
 pure nitrogen, free from argon. Lord Rayleigh no longer found 
 
EQUIVALENT AND VOLUME. 
 
 195 
 
 14.04, but 14.00 as the weight of one volume of nitrogen. 
 This, accordingly, is the volume weight of nitrogen. 
 
 8. In the same way, the volume weight of oxygen must be 
 16. For the two volumes of hydrogen gas, equivalent to one 
 volume of oxygen, prove oxygen to be divalent. The equiva- 
 lent weights 1 to 8 are as 2 to 16 ; hence one volume of oxygen 
 gas should weigh 16, one of hydrogen gas weighing 1. 
 Actual weighings have confirmed this conclusion. 
 
 9. For practical purposes the UNIT OF GAS VOLUME is 
 that containing one milligramme of hydrogen; under common 
 conditions of temperature and pressure, 12 cc. To determine 
 this unit under any given conditions of pressure and tempera- 
 ture, find the volume occupied by the hydrogen gas generated 
 from 12 mgr. pure magnesium. See 18, 9. 
 
 10. The valence of carbon cannot be determined directly, 
 because carbon is not known as a gas. But fixed air contains 
 8 oxygen to 3 carbon (31, 7) ; or two equivalents of oxygen to 
 one equivalent of carbon weighing 6 (31, 8). But direct ex- 
 periments show, that when carbon is burnt in oxygen, the gas 
 volume does not change. Since now one volume of oxygen is 
 equivalent to two volumes of hydrogen, carbon must have the 
 valence 4. All the numerous compounds of carbon confirm 
 this conclusion. 
 
 11. THE VALENCE of a gas is the number of volumes of 
 hydrogen chemically equivalent to one volume of the gas. 
 By electrolysis we have found chlorine to be monovalent, 
 oxygen divalent and nitrogen trivalent; that is, these gases 
 have respectively the valence 1, 2, 3. By reasoning and cal- 
 culation, carbon is tetravalent. All of organic chemistry will 
 confirm this conclusion. 
 
 12. If three decomposing cells, charged with muriatic 
 acid, water, and ammonia, are inserted in series in the circuit 
 of a battery— say of eight Bunsens — the hydrogen gas, at the 
 negative electrodes, will always be of exactly the same volume 
 
198 
 
 LECTURE 38. 
 
 in all three decomposing cells, in accordance with the general 
 law of Faraday (36, 9, 10). At the positive electrode, the 
 volume of chlorine will be equal to that of the hydrogen ; the 
 volume of oxygen will be half, that of nitrogen one third the 
 volume of hydrogen. This form of experiment, due to Hof- 
 mann (p. 34) strikingly shows that Cl, O and N have the 
 valence 1, 2, 3. 
 
 Notes 8. Such gas weighings, for the purpose of verifying the data 
 given, are readily made, without the use of air pump, by taking the 
 hydrogen filled tube as standard of comparison. 
 
 I use a LT-tube with side tubes and perforated ground glass stopper, of 
 capacity 50 to 100 cc, and with fine wire for suspension to balance; weigh 
 to tenth milligramme. For each gas to be weighed, a Kipp generator is 
 used, but only one set of absorption and drying tubes, as slow but com- 
 plete displacement is required anyway. 
 
 First, fill tube with pure, dry hydrogen and weigh; say the weight is a. 
 Then connect with oxygen-Kipp, and weigh again; say it is b. Also 
 fill with fixed air; let weight be c. Evidently b-a is the weight of oxygen 
 over hydrogen, proportional to 16-1 = 15; and in the same way c-a is 
 proportional to 22-1=21. That is, the experiment must show the differ- 
 ence c-a, divided by the difference b-a to be equal to 21 divided by 15, 
 which is 1,40. Actual experiment will show this to be the case, very 
 nearly, and thus verify the statement, made in the lecture. It is evident 
 that c-a divided by 21 should be very nearly equal to b-a divided by 15; 
 for both quotients represent the weight of the dry hydrogen gas filling 
 the weighing tube This checks the accuracy of the work done. 
 
 Finally, if at the same time a determination of the unit volume, 
 (approximately 12 cc) has been made, while the weighings were going on 
 (see section 9), and if the capacity in cc of the weighing tube has been 
 ascertained beforehand by weighing it with air and with water, the 
 weight of the unit volume of hydrogen gas will be determined by divid- 
 ing that unit volume into the volume of the weighing tube, giving the 
 NUMBER of unit volumes handled; dividing this number into the weight 
 of hydrogen filling the tube, as just determined, will give the weight of a 
 unit volume of hydrogen gas. This should be equal to one. 
 
 Since hydrogen gas escapes readily, even during a weighing, and as all 
 other gases replacing it are heavier, the weight is likely to be found a 
 trifle above one. Morley’s results. 
 
39. EQUIVALENT AND HEAT. 
 
 1. The determination of the volume of substances by the 
 method just described, is palpably restricted to gaseous 
 bodies; to the much larger class of metals it is inapplicable. 
 As has first been shown in 1819, by DULONG and PETIT, a 
 determination of the specific heat of metals will establish 
 this volume. 
 
 2. All amounts of heat are measured in gramme -degrees 
 (25.11). The instrument used for such measurement is 
 called a CALORIMETER. It consists of a metallic vessel, 
 provided with stirrer and a sensitive thermometer; it is placed 
 in another metallic vessel to minimize the loss of heat to the 
 surroundings. Details of construction belong to laboratory 
 practice. 
 
 3. Usually water is used as the HEAT MEASURING LIQUID. 
 Suppose 100 cc water were used in the calorimeter; and suppose 
 the temperature reads 20 degrees. If now 10 cc boiling water 
 (of 100 degrees) be added, the temperature will rise to 27.3 
 degrees. 
 
 The 100 cc originally in the calorimeter rose 7.3 degrees, 
 amounting to 730 gramme-degrees. The 10 cc were cooled 
 from 100 to 27.3 degrees, or 72.7 degrees, giving off 727 gro 
 or practically as much as the 100 cc gained. 
 
 4. If, under the same circumstances, 100 grammes of sheet 
 COPPER, in the form of bent cuttings, be rapidly transferred 
 from a beaker with boiling water to the calorimeter charged 
 with 100 cc water of 20 degrees, the temperature will also rise 
 to very nearly 27.3 degrees. Hence, 100 gr. copper yield 
 as much heat as 10 degrees water in the preceding experi- 
 ment; or one gramme of copper carries no more heat per 
 degree, than one-tenth of a gramme of water. 
 
 5. The amount of heat required to change the temperature 
 of one gramme of any substance one degree (centigrade) is 
 called the SPECIFIC HEAT of that substance. For copper it 
 
198 
 
 LECTURE 39. 
 
 has just been found to be 0.1, very nearly. Careful experi- 
 ments, allowing for all influences, make it 0.094. 
 
 6. If we multiply the specific heat by the equivalent, we 
 obtain the EQUIVALENT HEAT, that is, the amount of heat 
 (in gro) required to change the temperature of one gramme - 
 equivalent one degree. The following table gives the deter- 
 minations of specific heat, mainly by REGNAULT (1840). 
 
 7. TABLE of specific heat, equivalent weight (Eq.) and 
 equivalent heat (Eq. H) of the principal metals. 
 
 Metal. 
 
 Sp. 
 
 Eq. 
 
 Eq. H. 
 
 Metal. 
 
 Sp. 
 
 Eq. 
 
 Eq. H. 
 
 Na. . . . 
 
 0.293 
 
 23 
 
 6.74 
 
 Cu. . . . 
 
 0.094 
 
 31.8 
 
 2.98 
 
 Mg. . . . 
 
 0.250 
 
 12 
 
 3.00 
 
 Ag. . . . 
 
 0.057 
 
 108 
 
 6.16 
 
 Al. ... 
 
 0.214 
 
 9 
 
 1-93 
 
 Cd. . . . 
 
 0.057 
 
 66 
 
 3-76 
 
 Ka. . . . 
 
 0.166 
 
 39 
 
 6.47 
 
 Hg. . . . 
 
 0.033 
 
 100 
 
 3-30 
 
 Fe. ... 
 
 0.II4 
 
 28 
 
 3-19 
 
 Au. . . . 
 
 0.032 
 
 66 
 
 2.1 1 
 
 Zn. ... 
 
 0.096 
 
 32.5 
 
 3-13 
 
 Pb. ... 
 
 0.031 
 
 104 
 
 3.22 
 
 8. Of these metals, sodium and potassium were, already 
 by Berzelius, considered to be equivalent to hydrogen, or in 
 our modern language, to be monovalent. Their equivalent 
 heat is about 6.5. Silver comes the nearest. The mean of 
 these three is 6.44. This, therefore, is the equivalent heat 
 of metals having the VALENCE ONE. 
 
 9. The seven metals: Mg, Fe, Zn, Cu, Cd, Hg and Pb 
 show equivalent heat a little above 3. The mean of all is 
 3.23. This is evidently half the value of the preceding 
 group. Doubling 3.23 give 6.46, practically identical with 
 the equivalent heat of the monovalent metals. Two equiv- 
 alents must be taken to get the same heat capacity, 6.5. 
 
 10. The equivalent heat of A1 and Au averages 2.02, very 
 nearly one-third of that of the first group. The specific heat 
 of three equivalents of these metals is 6.06. Gold and alum- 
 inium must, therefore, so far as heat is concerned, be taken in 
 three equivalents. 
 
 11. The specific heat of carbon varies greatly with tem- 
 perature and condition. For charcoal it is 0.241, for graphite 
 0.197 and for the diamond 0.147. No conclusion as to val- 
 
EQUIVALENT AND HEAT. 
 
 199 
 
 ence should be drawn from these data, which simply illustrate 
 the allotropic conditions of carbon. The specific heat of 
 carbon rapidly increases with the temperature. At some tem- 
 perature it is concordant with the other substances. See 42 
 and compare 38.10. The specific heat of S, 0.177 and lo, 0.054. 
 with the equivalents 16 and 127 give 2.83 and 6.86. Hence, 
 S is divalent, lo monovalent. 
 
 12. For the gases H, N, O, the specific heat has been 
 found 3.41, 0,244 and 0.218. The equivalents being 1, 4| and 
 8, the equivalent heats are 3.41, 1.14 and 1.74. This agrees 
 with the valence as determined by electrolysis. 1, 3, 2, yield- 
 ing 3.41, 3.42 and 3.48 respectively for 1, 3, and 2 volumes. 
 
 Thus the valence of metals and non-metals is concordantly 
 determined by volume and by specific heat. 
 
 40. ATOMS AND MOLECULES.. 
 
 1. The solution of metals showed that certain definite 
 WEIGHTS of the different metals are chemically equivalent. 
 One hydrogen was found equivalent to 12 magnesium, 28 iron 
 and 100 mercury. In electrolysis it was found that equal 
 quantities of electricity set free the same equivalent weights 
 of metals. 
 
 2. But these equivalent weights are not of the same value 
 in reference to heating and space-occupying capacity; still, 
 they differed in simple ratios, requiring one, two, three or 
 four equivalents to obtain the same heat capacity, or having 
 the space-occupying capacity of 1, 2, 3, 4 equivalents of 
 hydrogen gas. — Here we have exclusively FIXED, SIMPLE 
 MULTIPLE PROPORTIONS. 
 
 3. Neither equivalent alone, nor valence alone, fully char- 
 acterizes any given kind of matter, such as H, O, N, C or Ka, 
 Mg, Al; Si; both are required and expressed in the higher 
 chemical unit, the ATOM. 
 
 AN ATOM IS A RELATIVELY INDIVISIBLE PARTICLE OF 
 MATTER. It possesses a definite number of valencies, acting 
 
200 
 
 LECTURE 40. 
 
 like single EQUIVALENTS. That is, the atomic weight is 
 equal to the product of its valence into its equivalent weight. 
 
 4. Hydrogen is the chemical unit, being the smallest. Its 
 equivalent is one, its valence is one; hence also its atomic 
 weight is one. 
 
 Oxygen has a valence two, and its equivalent is 8; there- 
 fore its atomic weight is 16. Nitrogen has a valence 3, its 
 equivalent is 4S; hence its atomic weight is 14. Carbon has 
 the valence 4, the true equivalent 3, the atomic weight 12. 
 
 5. The product of equivalent into specific heat for Ka, Na, 
 Ag was 6.4 (39.8) ; their valence is one, and therefore their 
 atomic weight the same as their equivalent weight. For the 
 magnesium group (39.9), the corresponding product has to be 
 doubled, hence the valence is 2, and the atomic weight twice 
 their equivalent weight. For aluminium and gold (39.10) the 
 product has to be trebled to make it equal to 6.4; hence the 
 valence is 3, and the atomic weight three times the equivalent. 
 For carbon the valence is 4. 
 
 6. In this manner we obtain the following preliminary table 
 of atomic weights, arranging the metals vertically according 
 to their electro-chemical character first, their valence next, 
 and in each line according to the magnitude of their atomic 
 weight. The metals in each line form a group or GENUS, 
 designated by name and Greek symbol, essentially as in my 
 Atomechanics of 1867. 
 
 Since carbon forms the natural center of this group, we shall 
 call this the carbon system of metals — the metals predominat- 
 ing in number. 
 
 7. THE CARBON-SYSTEM OF VOLATILE METALS, giving 
 incrustation on charcoal. 
 
 Electro. 
 
 Val. 
 
 Name. 
 
 Sym. 
 
 ISt. 
 
 2 nd. 
 
 3 id. 
 
 4 th. 
 
 Sth. 
 
 Positive, 
 
 I. 
 
 Kaloids, 
 
 Ka 
 
 Li 
 
 7 
 
 Na 27 
 
 
 
 
 
 2. 
 
 Cadmoids, 
 
 Kd 
 
 Be 
 
 9 
 
 Mg 24 
 
 Zn 65.5 
 
 Cd 112 
 
 Hg 200 
 
 
 3- 
 
 Styptoids, 
 
 2r 
 
 Bo 
 
 1 1 
 
 A1 27 
 
 Ga 70 
 
 In 1 14 
 
 T1 204 
 
 Neutral, 
 
 4- 
 
 Adamantoids, 
 
 , A4 
 
 C 
 
 12 
 
 Si 28 
 
 Ge 73 
 
 Sn 118 
 
 Pb 207 
 
 
 3- 
 
 Phosphoids, 
 
 4) 
 
 N 
 
 H 
 
 P 31 
 
 As 75 
 
 Sb 120 
 
 Bi 208 
 
 
 2. 
 
 Sulphoids, 
 
 0 
 
 () 
 
 i6 
 
 8 32 
 
 Se 79 
 
 Te 124 
 
 
 Negative, 
 
 I. 
 
 Chloroids, 
 
 X 
 
 FI 
 
 19 
 
 Cl 35-5 
 
 Br 80 
 
 lo 127 
 
 
ATOMS AND MOLECULES. 
 
 201 
 
 Secondary, lighter, earth -forming groups: 
 
 Positive, i. Kaloids, Ka Ku 39 Rb 85 Cs 132 
 
 2. Calcoids, Xa Ca 40 Sr 88 Ba 137 
 
 The kaloids are the most strongly electropositive, the 
 chloroids the most strongly electronegative ; the intermediate 
 groups are electrically intermediate. Compare 36, 7. 
 
 8. A corresponding group of non-volatile metals, giving 
 NO INCRUSTATION ON CHARCOAL and less plainly charac- 
 terized in valence, may be called the IRON SYSTEM OF 
 METALS. Increase of atomic weight increases the electro- 
 positive character (contrasting with carbon system). 
 
 Most Va 
 
 Negative, 
 
 Moljbdoids, 
 
 
 Cr 52 
 
 Mn 55 
 
 Mo 
 
 96 
 
 Wo 
 
 185 
 
 
 Sideroids, 
 
 
 Fe 56 
 
 Ni 58 
 
 Ru 
 
 104 
 
 Ir 
 
 193 
 
 
 Palladoids, 
 
 
 Co 59 
 
 Pd 
 
 106 
 
 Pt 
 
 194 
 
 Positive, 
 
 Cuproids, 
 
 Kv 
 
 Cu 63.5 
 
 Ag 
 
 108 
 
 Au 
 
 197 
 
 9. The atomic weights here given are used in the calcula- 
 tion of analyses and in the preparation of solutions and com- 
 pounds. The terms milligramme-atom and gramme-atom are 
 readily understood; a mgr. at. is the number of milligrammes 
 equal to the atomic weight. Thus a mgr. at. of silver is 108 
 mgr. silver, and a gr.at. sulphur is 32 grammes of sulphur. 
 
 10. A MOLECULE is the smallest number of atoms form- 
 ing a physical system, moving as a single body. 
 
 IN THE GASEOUS STATE, and under the same temperature 
 and pressure, the molecular volume of all substances is the 
 same (LAW OF AVOGADRO, 1811). 
 
 The practical unit of weight being the milligramme, the 
 mgr. molecular volume of any substance in the gaseous state 
 is the number of cc occupied by 2 mgr. of hydrogen gas. 
 
 11. This law gives a ready means for the DETERMINATION 
 OF THE MOLECULAR WEIGHT of volatile substances by 
 methods resembling specific gravity determinations. It is only 
 necessary to determine the volume v in cc, occupied by a 
 known weight, w mgr. Under the same conditions of tem- 
 perature and pressure, 24 mgr. Mg. yield q cc hydrogen gas. 
 
202 
 
 LECTURE 40. 
 
 to be determined by direct experiment (38, 9). Hence the 
 V cc gas represent v divided by q mgr. molecules; let this 
 number be n. Then the weight w, is n mgr. molecules, each 
 one molecule therefore weighs w divided by n. 
 
 12. Such determinations constitute an essential part of all 
 laboratory work. It is carried out by means of my gas 
 burettes, with or without air lock, and also by the Victor 
 Meyer displacement apparatus. 
 
 Experiments show that, as for hydrogen, so for oxygen, 
 nitrogen and chlorine, also for vapors of bromine and iodine, 
 the molecule consists of two atoms. For water, carbon dioxide 
 and other gases obtained by synthesis, the molecule consists 
 of one atom only, such as H 2 O; CO 2 . 
 
 Notes. That chemical compounds differ from mixtures in having 
 their constituents united in fixed, definite proportions, was more or less 
 understood over a century ago. The investigations of Wenzel and 
 especially Richter (p. 33) on neutral salts and the combining propor- 
 tions of acids and bases, made this clear. It was however, drawn in 
 question by no less a chemist than Berthollet (p. 32), but settled against 
 him by Proust. 
 
 Dalton (p. 32), comparing the different oxides of metals and a few 
 gases as to composition, found that all facts known could be expressed 
 by saying: substances combine in fixed, simple multiple pro- 
 portions BY WEIGHT. Being a thinker, as well as a chemist, he con- 
 ceived the idea of limited particles of matter, each kind having a definite 
 weight of its own; such particles would combine only in fixed and simple 
 multiple proportions For the name of these particles he revived the 
 term atom from the old Greek philosophers, who thereby designated the 
 final, indivisible particles of matter. 
 
 Independent of all philosophical speculation, the chemical atom, as 
 defined by us, is as real as matter itself. The chemical atom is rela- 
 tively INDIVISIBLE, that is, in reference to the substance which is com- 
 posed of these atoms. Atoms of water are indivisible as such; for if 
 divided, water ceases to be constituted by them; we have only atoms of 
 the constituent hydrogen and oxygen. 
 
 This idea of relative indivisibility is not restricted to chemistry, but is 
 quite general. A book, a flower, an animal, also are as indivisible as the 
 atom — in relation to the kind of being they are. In other words, the 
 final philosophical question of the limited divisibility of matter in gen- 
 eral is not part of the question of the reality of chemical atoms. 
 
 A certain prominent modern chemist denies the reality of chemical 
 atoms — but he also denies the reality of matter. A chemist denying 
 matter is exclusively a modern phenomenon. 
 
41. ELEMENTS AND COMPOUNDS. 
 
 1. We have begun the study of chemistry proper with the 
 study of THE METALS. This well defined and most im- 
 portant class of bodies also formed the starting point for the 
 chemists of old. For about a century, this natural and to all 
 familar group of bodies, has been put into the back ground by 
 chemists. We deliberately have begun our course in chemistry 
 with the substance rather than with the shadow. 
 
 2. We have also noted a class of bodies called non-metals, 
 comprising sulphur, carbon, iodine. To this group we after- 
 wards added the noted gases hydrogen, oxygen, nitrogen and 
 chlorine. These bodies combined with the metals, forming 
 new bodies, chemical compounds. By heat, and notably by 
 electricity, we have decomposed these compounds, reproducing 
 the original metal at the negative electrode, and recognizing 
 the non-metals as electro -negative substances. 
 
 3. Looking at the grouping of the metals in 40, 7 and 
 and 8, we are struck with the MANY RELATIONSHIPS brought 
 to our mind in tracing the lines from right to left, following 
 the species of a genus with increasing atomic weight, or up 
 and down, according to varying valence and electrical con- 
 trast. They look not at all like independent substances, but 
 rather like compound bodies, systematically arranged accord- 
 ing to their composition. 
 
 4. Nevertheless chemists, the world over, have considered 
 these bodies to be simple substances, not compound. Modern 
 chemists have derided their predecessors of two thousand years, 
 who looked upon the metals as compounds, the alchemists even 
 deliberately trying to change one metal into another. Are the 
 chemists right and were the old chemists in error? Let us 
 examine the facts without prejudice. 
 
 5. The principal means of decomposition at hand are 
 increase in temperature and electrical tension and current. We 
 
204 
 
 LECTURE 41. 
 
 have exemplified the use of both these powers. Thus far, the 
 metals have resisted both of these powers under all conditions. 
 They clearly form a class of matter different from ordinary 
 compounds, which we have decomposed. Hence, they ought 
 to be designated by a distinctive name. We properly adopt 
 their common name CHEMICAL ELEMENTS. The non-metallic 
 elements are commonly called METALLOIDS. 
 
 6. But the definition of this term should be in accordance 
 with fact. A CHEMICAL ELEMENT IS A SUBSTANCE THAT 
 HAS NOT BEEN DECOMPOSED. To say that it CANNOT be 
 decomposed would be to assert that those who succeed us will 
 be limited by our powers and our knowledge. Such assertions 
 are manifestly unwarranted and unscientific. History has 
 often proved them to be false. 
 
 7. As to volume in the gaseous state, the elements deport 
 themselves exactly as compounds. The molecular volume is 
 the same for all. There is no difference whatever in this 
 most fundamental relation between the elements and com- 
 pounds. 
 
 8. As to specific heat there is a radical difference. Berth - 
 elot has first recognized and formulated it (1873). The 
 specific heat of an atom of any chemical element is the same 
 (39), entirely independent of the weight of that atom, though 
 this weight varies from 1 to over 200! But for a series of 
 compounds, resembling one another, the specific heat of the 
 compound atom is almost directly proportional to the atomic 
 weight. 
 
 9. 1 have shown that there is also a radical difference be- 
 tween the effect of the SUBSTITUTION of an element and a 
 compound on the properties produced (1892). In certain 
 simple organic compounds called PARAFFINS, one hydrogen 
 atom may be replaced by an atom of FI, Cl, Br, lo or Cyan- 
 ogen, which is Cy — CN, a compound radical of the atomic 
 weight 2G. The boiling point increases with the atomic 
 weight of the elements in these substitutions, as shown in 
 
ELEMENTS AND COMPOUNDS. 
 
 205 
 
 the diagram, page 77. Here Cy is at the top, showing the 
 greatest increase, more than for Io=127; in fact, for an ele- 
 ment it would require an atomic weight of 150. Yet the rad- 
 ical has only the atomic weight 26. 
 
 10 Both of these striking differences between elements 
 and compounds were fully accounted for on mechanical prin- 
 ciples in my notes presented by Berthelot to the Academy of 
 Sciences of Paris (1892). The conclusion is not, that the 
 elements are really simple bodies, but that the constituent 
 particles of their atoms are at relatively small distances, as 
 compared to the relatively great distances of the element 
 atoms in ordinary compounds. 
 
 11. Thus the question as to the simple or composite nature 
 of the chemical element stands in the following position. No 
 chemical element has thus far been actually decomposed ; 
 the observations of Lockyer (1879) and Crookes do not war- 
 rant the conclusion drawn by these scientists. But at the 
 same time, not a single fact is known proving or indicating 
 that the elements are not composite substances; on the con- 
 trary, their mutual relationship, exhibited in the tables (40, 
 7, 8). showing their properties to vary with weight and val- 
 ences, is a positive indication of their being compounds. 
 
 12. The pretended exact atomic weights of Stas (p. 33) 
 are commonly considered to prove that the elements cannot be 
 compound bodies; but these data have been shown to be 
 erroneous in my communications to the Academy of Sciences 
 of Paris and in my True Atomic Weights, 1894. The values 
 of Stas are not constant, but vary with the amount of sub- 
 stance used. See p. 79. In this work, the so-called “Peri- 
 odic Law ” of the common text books is also examined. 
 
 The first extended publication on the natural classification 
 and cofnposite nature of the elements was made in my 
 Programme of Atomechanics, 1867. 
 
42. ALLOTROPY AND ISOMERY. 
 
 1. The three substances charcoal, graphite and the dia- 
 mond, have been known to man from very early times. 
 They are as different from one another as any other three 
 bodies possibly could be. No chemist suspected these bodies 
 to be related in any way, until in modern times. The trans- 
 parent and most valuable gem (10, 12), the marking substance 
 of our pencils, and the charred remains of wood, seemed to 
 be bodies entirely unrelated. 
 
 2. Nevertheless, these three bodies are hot only related, 
 but they are chemically one and the same element carbon, in 
 three different (ALLOTROPIC) states or conditions. Berzelius 
 coined the word used; it explains nothing, only fixes in our 
 mind, by a special term, a special set of facts. Other 
 elements, especially S, P, O also show allotropy. 
 
 3. The following properties are common to all forms of 
 carbon, and thus characterize the SPECIES of matter chemists 
 designate by the symbol C : Solid, infusible and non-volatile 
 in the highest heat of our furnaces, but volatilizing (boiling?) 
 in the electric arch; combustible, at least in pure oxygen, at a 
 red heat, yielding eleven -thirds of its own weight of carbon 
 dioxide gas and nothing else; it is insoluble in all ordinary 
 solvents, but dissolves readily at the highest temperatures 
 (electric furnace) in many molten metals. 
 
 4. That even the DIAMOND IS COMBUSTIBLE, was first 
 suspected by Newton (1740), because of its high refractive 
 power. The combustion of the diamond was first effected in 
 oxygen by Lavoisier, who thus established its true chemical 
 nature. The TEMPERATURE OF IGNITION varies greatly 
 with the form of carbon. Certain charcoals, made of willow 
 wood at low heat, ignite at correspondingly low temperatures 
 and are used for gunpowder. Graphite and diamond do not 
 burn even in oxygen until at a bright red heat. 
 
ALLOTROPY AND ISOMERY. 
 
 207 
 
 5. Carbon dissolved in molten iron (cast iron contains 
 5 per cent.) may crystallize on cooling. This form is invari- 
 ably GRAPHITE, soft, readily marking paper and wood 
 (pencils), G 2.2 and rhombohedral. When such a carbon 
 solution in iron is suddenly chilled on the surface, to solidifica- 
 tion, the interior is compressed by the shrinking of the solid 
 crust, and the carbon crystallizes, under this high pressure, 
 as DIAMOND (Moissan). 
 
 6. The various common forms or VARIETIES OF CARBON, 
 both mineral and artificial, have been sufficiently indicated. 
 See 5, 2.3; 10, 12; 12, 10. Bituminous coals, when heated 
 in a retort or oven, leave a COKE, corresponding to the-char- 
 coal left by wood under like conditions. Resinous substances 
 yield lamp black, the lightest form of carbon. Bones give 
 animal charcoal, the noted absorbent for color and other 
 matters. The volatile portion of bituminous coals, purified, is 
 illuminating gas. • 
 
 7. PHOSPHORUS also presents itself in two allotropic con- 
 ditions, namely ordinary amber colored and red phosphorus. 
 By keeping ordinary phosphorus heated to 240 degrees for ten 
 days continuously, it is converted into the red modification. 
 To remove the small parts of the common (poisonous) phos- 
 phorus from the red (non-poisonous) modification, the cold 
 mass is treated with bisulphide of carbon, which dissolves the 
 common and not at all the red phosphorus. 
 
 8. The following additional contrasting properties are 
 worthy of notice. The property first given applies to common 
 phosphorus; the corresponding property of the red modifica- 
 tion is put into parenthesis. 
 
 Specific gravity, 1.83 (1.9G). Phosphorescent on surface 
 (not). Inflammable at 60 degrees (230 degrees) . Violently 
 attacked by nitric acid (only slightly attacked when heated), 
 making this a dangerous reaction (comparatively safe). 
 Crystallizes at common temperatures (at 580 degrees). 
 
 9. SULPHUR also exhibits allotropic modifications. Its 
 dimorphism has been fully presented (21, 6.7). When limpid 
 
208 
 
 LECTURE 42. 
 
 melted sulphur (113 to 120 degrees) is heated to about 200 
 degrees, it becomes viscid ; above that temperature it again 
 becomes a limpid liquid. The viscid sulphur (at 230) poured 
 into water, stays soft for a long time, and is used for taking 
 molds. 
 
 10. OXYGEN GAS under the influence of electrical dis- 
 charges — even in electrolysis (37.7) — changes to ozone, the 
 more active form of oxygen. Silver is not attacked at common 
 temperatures by pure, dry oxygen ; ozone promptly blackens 
 it. The density of ozone is 50 per cent, in excess of that of 
 oxygen; that is, while oxygen gas has the molecules O2, 
 those of ozone are O3 . Ozone readily reverts to oxygen; a 
 moderate heating is sufficient for this change. 
 
 11. A chemical compound existing in two or more physically 
 different forms is called ISOMERIC. Thus mercuric iodide 
 shows two isomeric forms, the red and the yellow (23, 7.8). 
 Mercuric sulphide, precipitated from its solutions by hydrogen 
 sulphide, is black (22, 8 and notes). By heating, this black 
 sulphide changes to a red sublimate, cinnabar. White arsenic 
 crystallizes on a hot surface prismatic, on a cold surface octa- 
 hedral ; on a very hot surface it condenses to a vitreous mass, 
 which gradually turns opaque like porcelain. 
 
 12. The phenomena of allotropy and isomery must evi- 
 dently be carefully considered when the nature of the elements 
 is to be investigated. Dimorphism may be looked upon as the 
 expression of two positions of equilibrium, as already demon- 
 strated in my programme of 1867. Allotropy is probably also 
 dependent on the formation of more complex molecules, by the 
 grouping of more atoms, as is plainly proved in the case of 
 oxygen and ozone. 
 
43. BINARIES AND TERNARIES. 
 
 1. Two elements combining, form a binary compound; 
 three elements united, form a ternary compound. But nearly 
 all compounds being DUAL, as we have seen quite early in 
 the course, and as has been confirmed by electrolysis, we 
 more properly look upon compounds as containing TWO con- 
 stituents only, one or both of which may be compound 
 radicals. Lect. 31. 
 
 2. The electropositive constituent of a compound is a metal 
 (in salts) or hydrogen (in acids) ; the metal and hydrogen 
 being interchangeable by substitution. If therefore, the 
 FORMULA OF THE ACID be given or remembered, it is easy 
 to state the formula of the corresponding salt, provided the 
 valence of the metal be known. Substitution taking place, 
 not atom for atom, but equivalent (i. e. unit of valence) for 
 equivalent. 
 
 3. For example, the formula of hydrochloric acid or HYDRO- 
 GEN CHLORIDE is H Cl ; both constituents being monovalent, 
 the atomic and equivalent formula are identical. Now Ag 
 being monovalent, Ag CL^e will be expressed by the formula 
 Ag Cl. But zinc is divalent, hence its chloride has the formula 
 Zn CI2. Bismuth being trivalent, its chloride is represented 
 by the formula Bi Cl 3. The number of monovalent negatives 
 must equal the valence of the positive constituent. 
 
 4 . If now instead of Cl we have any other chloroid, the 
 formula will remain the same, only the second symbol will 
 change. Thus silver fluoride Ag FI. Zinc bromide Zn Bi'a. 
 Bismuth iodide Bi I03. These are all binaries proper. Even 
 the radical cyanogen, Cy or CN gives compounds of this 
 structure and named like a binary, cyanide. Thus Ka Cy 
 represents potassium cyanide, Ba Cyo barium cyanide. 
 
 5. If instead of starting with hydrogen chloride, we start 
 with NITRIC ACID, H N^te, the formula of which is H O3N, we 
 still can write the formula as before, for NlTRATpS ARE DUAL 
 COMPOUNDS, CONTAINING THE MONOVALENT RADICAL 
 
210 
 
 LECTURE 43 . 
 
 O3N AS ELECTRO NEGATIVE. Thus silver nitrate has the 
 formula Ag O3N; barium nitrate Ba (03N)2, bismuth nitrate 
 Bi ( 03 N) 3 . 
 
 Chlorates correspond exactly to nitrates. Thus KaCl^te 
 has the formula Ka O3CI; BaCl^te is Ba (0301)2. 
 
 6. OXIDES are binaries containing the divalent electro- 
 negative ELEMENT oxygen. The formulae H2O, Ba O, Ka20, 
 Zn O, CO2, Si O2 are perfectly normal, the valence of the 
 negative balancing that of the positive constituent. For 
 phosphoids, to avoid fractions, we write P2O3; but this in- 
 volves a question, which we must leave untouched at present. 
 
 Sulphides correspond exactly to oxides; Zn S, C S2, Ba S. 
 
 7 . SULPHATES correspond also to oxides, containing the 
 DIVALENT RADICAL O4S instead of oxygen; our S^te is 
 =04S. Thus the formula of sulphuric acid is written H2O4S ; 
 Ba Sate is Ba O4S. Potassium sulphate Ka204S. Zinc sul- 
 phate Zn O4S. 
 
 Chromates contains the divalent radical 04Cr, SUL- 
 PHITES the divalent radical O3S. Consequently lead chro- 
 mate is Pb 04Cr and calcium sulphite Ca O3S. 
 
 CARBONATES contain the divalent radical O3C. Hence 
 zinc carbonate Zn O3C. 
 
 8. NITRIDES contain the trivalent element nitrogen as 
 negative. The most important nitrides are those of the triva- 
 lent phosphoid group. For example, ammonia H3N, phos- 
 phuretted hydrogen H3P, arseniuretted hydrogen H3 As. 
 
 The nitrides of the chloroid group are all explosive. Thus 
 N CI3 is perhaps the most explosive of all substances. 
 
 9 . PHOSPHATES, normal, contain the TRIVALENT RADI- 
 CAL O4P; hence their formula may be written exactly as that 
 of a nitride. The acid is H3 O4P. Potassium phosphate 
 Kas O4P. 
 
 ARSENATES correspond to the phosphates. H3 O4AS is 
 arsenic acid, Ag3 O4P represents normal silver phosphate. 
 
 It is not necessary to give cases of tetravalence at this place. 
 They will be understood when they occur. 
 
BINARIES AND TERNARIES. 
 
 211 
 
 10. It is evident that for example, in sulphates, the two 
 hydrogen atoms of the acid need not both be replaced by a 
 metal; in that case we obtain a so-called ACID SALT, com- 
 monly designated by the prefix bi — . Thus H 2 O4S, HKa 
 O4S and Ka 2 O4S represent H S^te, Ka bisulphate and Ka 
 Sate. The same terminology is applied to carbonates and sul- 
 phites. Thus HKa O3C represents Ka bicarbonate, and 
 HNa O3S represents Na bisulphite. 
 
 11. For the TRIVALENT RADICALS, such as O4P of phos- 
 phates, the three valencies H 3 may be represented by KaH 2 , 
 KasH or Kas ; such salts are termed monopotassic, dipotassic 
 and tripotassic phosphate. But also metals of other valence 
 may enter. Thus the crystallized ammonio-magnesium phos- 
 phate, precipitated from alkaline solutions, is O4P + 6 H2O. 
 The trivalent radical is saturated by the divalent Mg and the 
 monovalent ammonium Am. In the so-called microcosmic 
 salt, the three valencies are represented by one atom each of 
 sodium, ammonium and hydrogen; the salt contains four 
 atoms of water of crystallization. Write the formula. 
 
 12. These general rules and special examples may suffice 
 for the understanding of the writing and reading of chemical 
 formula. The common (now atomic) formula represent one 
 atom of the compound. The positive is generally a metal or 
 hydrogen. The electro -negative is an element (in binaries) 
 or a radical (in ternaries). It is the valence, that is, the 
 number of equivalents, that must balance in the formula as in 
 the compound. 
 
 The more general group formulas (Greek symbols of genera) 
 given already in our Atomechanik 1867, can only be mentioned 
 here. These general formula are also used in our treatise on 
 the statistics of crystal symmetry in the transactions of the 
 Academy of Sciences of Vienna for 1870. 
 
 Notes. A practical difficulty in the writing of chemical formulae 
 must yet be cleared up. We may say, in general, that the metals also 
 occur combined, forming radicals. 
 
212 
 
 LECTURE 43. 
 
 Thus mercury is considered divalent — in the mercuric series of com- 
 pounds. But in mercurous compounds^ we must consider two atoms of 
 mercury combined to form the divalent radical Hg2. 
 
 Again, ferrous compounds contain one atom of iron combined with 
 only two valencies of the negative; it is said that ferrous compounds are 
 NOT SATURATED. When oxidized to ferric, the iron radical Fe2 has 
 formed, with a valence 6. Ferric chloride contains 2 Fe as positive and 
 6 Cl as negative. Ferric sulphate contains the hexvalent Fea saturating 
 three divalent radicals O4S. 
 
 In like manner, the tetravalent Pt forms two series of compounds, the 
 PLATiNic and PLATINOUS. The first are considered normal, each Pt 
 being combined with four equivalents (valencies) of the negative element 
 or radical. In the platinous. each Pt is combined with two such valen- 
 cies only; these compounds are spoken of as non-saturated. 
 
 In the same manner we have Stannous (non-saturated) and Stannic 
 (saturated) compounds. 
 
 Fixed air, carbon dioxide, is considered saturated COg ; four valen- 
 cies or equivalents of the positive carbon being united with two divalent 
 oxygen atoms. But carbonic oxide is CO ; it is considered non-saturated, 
 but acts quite like a neutral body. 
 
 These few remarks have been added only to deal with the practical 
 points involved in the writing and reading of chemical formulae, not to 
 solve difficulties in valence. 
 
 Constitution of Ternaries. The author wishes it distinctly under- 
 stood that ALL the detail given even in elementary text books on this 
 subject is unreliable, useless and misleading; much thereof is in conflict 
 with crystallographic facts now commonly disregarded. Deeming it 
 improper, in a text book, to teach anything untrue and in conflict 
 with fact, all elegant structural formuhe of ternaries are deliberately ex- 
 cluded from this work. 
 
 What has been given on their constitution is perhaps both new and old — 
 new in not being found in the books of the day, and old in being conform 
 to the representations of an earlier day; but it has two good reasons for 
 a place in this text book, namely it is strictly conform to chemical and 
 electrolytical phenomena, and does not go beyond the solid basis of 
 experience. 
 
 Name of Ternaries. The ending is in t, indicating three elements 
 combined ; the connecting vowel is a for common, i for a less amount of 
 oxygen. In English, a final e is added to the t. Thus we have iron sul- 
 phate and sulphite. 
 
 The ternaries, with more oxygen than the .\te, take the prefix per, 
 those with less than ites take iivpo before the negative. Thus perchlor- 
 ates and hypochlorites. 
 
 If intermediate element of ternary be not oxygen (understood in pre- 
 ceding), then root of name must be inserted. Thus Ka S-As’te is potas- 
 
FORMULA AND COMPOUND. 
 
 213 
 
 sium sulph-arseiiite ; Am Cl-Pt^ife, ammonium chloro-platinate. As 
 intermediate occur mainly O, S; FI, Cl, Br, lo. Cy. Yellow prussiate is 
 Ka Cyo-Fe5i‘e, red prussiate Ka Cy'-Fe^^^e; Cy» reads cyano — , and Cy> 
 reads cyani. 
 
 44. FORMULA AND COMPOUND. 
 
 1. We have now exposed all the essential principles on 
 which the MODERN CHEMICAL FORMULA are constructed. 
 We have also given a sufficient number of examples to make 
 the practice of writing such formulae reasonably easy. We 
 regret the necessity of words of warning against the almost 
 universal ABUSE of these formula. 
 
 2. The student should always bear in mind, that the 
 CHEMICAL FORMULA of a compound IS NOT THE COM- 
 POUND itself. The name is not the thing. The word is not 
 the object. And yet it is a fact, that in lecture halls and 
 laboratories, in books and periodicals, the chemical formula is 
 made much more prominent than the chemical substance, or 
 its reactions and properties. 
 
 3. The chemical formula, if correct, is merely a symbolic 
 representation of one atom of the chemical compound. Above 
 all, it is applicable only to substances sufficiently pure, never 
 to crude materials. To refer, by chemical formulae, to crude 
 acids and ordinary chemicals, is false in every sense of the 
 word. Such a practice does not show learning, but proclaims 
 ignorance. 
 
 4. To avoid such practice, we have from an early day used 
 
 the simple abbreviation of the chemical names now familiar to 
 the student. H more brief than the name hydrogen 
 
 sulphate or sulphuric acid; it represents the actual DUAL 
 nature of the compound which must be known to understand 
 its reactions; it does not hide the chemical essence under a 
 string of letters or symbols such as H 2 O 4 S. 
 
214 
 
 LECTURE 44. 
 
 5 . Unless the radical is broken up in an exceptional re- 
 action, it acts like one thing, like an element atom; and any 
 expression hiding that fact, hides the mechanism of the 
 chemical reaction, hides that which we try to feach or to learn. 
 Besides, it does not put an undue strain on the memory, and 
 thus gives the mind a chance to think of the essential clearly. 
 
 6. Again, intricate formulas, supposed to represent re- 
 actions, are written on blackboards, and printed in books, for 
 students to learn ; and yet these formulas are not true, and the 
 reactions will not take place at all, if the materials are taken 
 strictly conform to these formulas. The chemical process 
 learnedly represented will simply not proceed. Such are, for 
 example, the long equations expressing the volumetric re- 
 actions of potassium permanganate with oxalic acid and 
 ferrous salts. 
 
 7 . As we shall not burden these pages with such formulae 
 ourselves, and as the lesson has to be brought home, we insert 
 the formulae referred to, exactly as they are found in the books. 
 
 2 K Mn O4 + 5 H2C2O4 + 3 H2SO4 = K2SO4 + 2 Mn SO4 
 
 + 10 CO 2 + 8 H 2 O. 
 
 10 Fe SO4 + 2 K Mn O4 + 8 H2SO4 = K2SO4 + 2 Mn SO4 
 + 5 Fe2 (804)3+8 H2O. 
 
 Now, if you will take precisely these quantities, the reaction 
 will not take place as expressed — the determination attempted 
 will be a miserable failure. The only result is the bewilder- 
 ing of the student. The real mechanism of the simple 
 chemical reaction is completely obscured by a cloud of irrele- 
 vant and false details. 
 
 8. PERMANGANATE, Ka 04 Mn, was first produced (1820) 
 and applied by my teacher in chemistry. Professor Forch- 
 hammer of Copenhagen. In the presence of oxidable ma- 
 terials, AND A LARGE EXCESS OF SULPHURIC ACID, it 
 breaks up, the Mn forming ordinary/ compounds as electro- 
 positive. Now, the only and the essential thing to know, is 
 that 2 permanganate will yield one Ka20 and 2 MnO, the 
 excess of acid attends to keeping them in solution. But this 
 
FORMULA AND COMPOUND. 
 
 215 
 
 accounts for 3 of the 8 oxygen ; hence 5 oxygen are set free 
 to do the work wanted done. 
 
 9. The effect of this oxygen on the oxidable matter is 
 equally simple. The ferrous FeO becomes ferric, FeaOg; 
 or 2 ferrous require one oxygen to become ferric, which is 
 kept in solution by the large excess of acid. The five oxygen 
 from two permanganate will therefore oxidize ten ferrous; that 
 is, ONE PERMANGANATE OXIDIZES FIVE FERROUS. This 
 gives the numerical relation wanted. By the way, the long 
 equation is still too short; green vitriol should have been re- 
 placed by hydrated ammonio -ferrous sulphate, which is the 
 true standard. See the blackboard diagram. 
 
 10. The books should be freed of such useless, complex 
 and incorrect show of chemical learning which only perplexes 
 and misleads the student. For one, the author will no more 
 introduce such sham chemistry in this textbook than he allows 
 it in his laboratory. We endeavor to study the actual process 
 in its essential and determining features, even if we lose the 
 appearance of learning. 
 
 11. To give chemical formula, when asked to describe a 
 chemical compound, is not giving an answer at all. The 
 characteristic properties of the substance determine its nature, 
 and not the formula. It is the substance we prepare, test 
 and use, not the formula. The substance may cure disease, 
 the formula can not do that. Compounds are not marked by 
 nature with chemical formulae, but by properties; it is by these 
 that we have to distinguish them. 
 
 12. The abuse of formulae is especially out of place at the 
 laboratory stand in qualitative analysis. The chemists of the 
 present have, under a new name it is true, returned to the 
 dualistic Berzelian constitution of compounds, always retained 
 by the author, and expressed in his simple signs. These two 
 constituents determine the reactions; the complete formula 
 only hides it from the eyes. 
 
45. PURITY AND STRENGTH. 
 
 1. A chemical compound should be pure, that is, contain 
 nothing but what its name implies and its formula indicates. 
 But such absolute purity is almost impossible to procure; only 
 for the most important atomic weight determinations is an 
 effort made to reach this limit. Commercial products, even if 
 marked C.P., are not absolutely pure. — See True Atomic 
 Weights, p. 140-142. 
 
 2. Although it may be extremely difficult to secure the 
 highest degree of purity, it is comparatively easy to prove 
 the presence of the foreign matter or impurity. The general 
 methods of QUALITATIVE CHEMICAL ANALYSIS (Lect. 22) 
 form the basis of the tests for impurities ; special tests of great 
 delicacy are sought for in particular cases. We shall consider 
 that subject soon. 
 
 3. Many chemicals it is impracticable to produce in the 
 free state; they are sold as solutions in some inert solvent. 
 This is the case with most acids and the volatile alkali, which 
 are sold in aqueous solution. For this class of bodies, it is 
 essential that nothing but the chemical and the inert solvent 
 be present, and that the amount of the active substance be 
 not below the per cent, stated. Here both purity and strength 
 are required. 
 
 4. All methods for the determination of the strength of 
 solutions and chemicals in general belong to QUANTITATIVE 
 CHEMICAL ANALYSIS. The scientific principles involved are 
 subjects proper for the lecture room, though the details of 
 manipulation and the minutiae of method to secure most 
 reliable results belong, with the practice, to the laboratory. 
 
 5. First of all, these quantitative methods may be distin- 
 guished as physical and chemical, according as mainly physi- 
 cal processes are employed, or the substance submitted to 
 chemical transformations by the use of. reagents. 
 
PURITY AND STRENGTH. 
 
 217 
 
 6. The PHYSICAL METHODS of determining the strength 
 of a given chemical consist in the determination of the so- 
 called PHYSICAL CONSTANTS of the substance, such as the 
 specific gravity, G; the fusing point, F; the boiling point, B; 
 also the refracting power; the rotation of the plane of polariza- 
 tion ; the solubility in certain neutral solvents, and the like. 
 The first three (G, F, B) are the most important. 
 
 7. There are two methods, depending exclusively on phy- 
 sical agencies, but accomplishing chemical changes in the given 
 substance; namely dissociation and electrolysis. DISSOCIA- 
 TION is chemical decomposition by heat alone; ELECTROLY- 
 SIS is chemical decomposition by the galvanic current. Both- 
 of these methods are capable of a high degree of precision ; 
 they are also rapid and simple in execution. 
 
 8. The CHEMICAL METHODS proper, involving the use 
 of reagents and producing chemical transformations of the 
 given substance, may be distinguished as gasometric, volu- 
 metric and gravimetric methods of quantitative analysis. 
 The first named is the most recent and the most rapid, but 
 unfortunately also the most restricted in applicability; the last 
 named method is the oldest and the slowest, but applicable in 
 all cases, and serves as standard of comparison for the others. 
 
 9. In GASOMETRIC ANALYSIS, the substance to be deter- 
 mined is acted upon by a reagent, setting free some gas; this 
 gas is measured, and its amount is proportional to that of 
 the compound to be determined. It is evident, that this reac- 
 tion must be rapid and complete, and affect exclusively the 
 substance to be determined. Gasometric analysis is entirely 
 distinct from GAS ANALYSIS proper, which treats of the 
 analysis (by absorbents) of mixtures of gases. Lect. 32. 
 
 10. In VOLUMETRIC ANALYSIS, the substance is brought 
 into solution, and treated with some reagent of definite 
 strength, called a NORMAL SOLUTION; this solution is added, 
 finally drop by drop, until the reaction intended is completed, 
 as INDICATED by some readily recognizable change in color 
 
.218 
 
 LECTURE 45. 
 
 or appearance. The volume of normal solution used, then fur- 
 nishes a measure of the strength of the substance. 
 
 11. In GRAVIMETRIC ANALYSIS, a weighed portion of the 
 substance is, by appropriate reagents, transformed into some 
 other definite combination, which can be readily and ACCUR- 
 ATELY WEIGHED. The weight so obtained, furnishes the 
 measure of the strength sought. Thus, a silver coin dissolved 
 in nitric acid, will give all its silver as precipitate, when a 
 chloride is added; this precipitate washed, dried, fused and 
 weighed, gives the weight of silver chloride; 0.7526 thereof is 
 silver, which thus becomes known. 
 
 12. Whatever method be used, in all cases the real 
 determination depends on one or more weighings. In volu- 
 metric processes, the reagents depend on weighings, and in all 
 cases the substance taken must be weighed. Accordingly, 
 THE BALANCE remains to-day, as it always has been, THE 
 REAL INSTRUMENT OF QUANTITATIVE CHEMICAL ANALY- 
 SIS, in all its varied forms and under all names. And in all the 
 operations of quantitative analysis, the chemical formulm and 
 atomic weights are the standards of comparison. This is the 
 legitimate use of chemical formula. 
 
 46. THE ANALYTICAL BALANCE. 
 
 1. The exposition of the general methods of quantitative 
 chemical analysis must begin with a short study of the analyti- 
 cal balance (2, 6) with AGATE BEARINGS. The handling of 
 this instrument is more important than its first cost. The 
 finest balance improperly handled, can give no reliable results, 
 while a good prescription balance, in glass case, and well 
 handled, gives results to 2 mgr. certain, and almost to the 
 single milligramme. 
 
 2. In this lecture course we shall, as a rule, consider 
 weighings to the milligramme only. These can be obtained 
 by the method of equal excursions of the POINTER (2, 8) 
 from the central line of the scale. 
 
THE ANALYTICAL BALANCE. 
 
 219 
 
 In actual laboratory practice, it is advisable to determine the 
 scale value in milligrammes; then a simple mental calculation 
 will give the true milligramme without frequent adjustment 
 of the pointer. 
 
 3. The analytical balance is provided with a RIDER which 
 can be moved to any division of the scale marked on the beam, 
 while the case is closed. Of course, the balance must be 
 arrested, as in every case of change of weights (2.8). By 
 such a balance, even the simple method of equal excursions, 
 will permit the determination of the tenth milligramme. 
 
 4. The balance should be PLACED on as firm and stable a 
 support as can be found, in good light, but protected from the 
 direct rays of the sun. The balance should be carefully 
 leveled, by means of a spirit level (independent of the unsatis- 
 factory box levels usually fastened to 'the balance). All 
 necessary adjustments should be made and revised at reason- 
 able intervals. Careful handling avoids frequent change of 
 adjustment. 
 
 5. A good balance should be provided with a separate stop 
 for the pans, in addition to the stop for the beam. Having 
 weighed a burden on the left pan, the balance should come to 
 the same equilibrium after exchanging the burden to the right 
 and the weights to the left pan ; this tests the EQUALITY OF 
 THE LEVER ARMS (2.6). 
 
 All trepidations, all unnecessary motions of any kind, should 
 be avoided, if a good balance is to remain so. See the instal- 
 lation at Breteuil (p. 39) ; the balances on isolated piers, 
 manipulations by rods from a distance, and the pointer ob- 
 served through telescopes. 
 
 6. THE WEIGHTS, if obtained from a good maker, will 
 stand the tests to a small fraction of a milligramme. First 
 compare the tens; then one of these with all units (5, 2, 2, 1). 
 Next balance the two tens against the one twenty. Finally 
 all these against the fifty. Like tests the fractional grammes 
 are subjected to. For all work here considered, these tests 
 should be fully met by the weights. For work of higher pre- 
 
220 
 
 LECTURE 46. 
 
 cision, the actual errors are determined in hundredths of the 
 milligramme by the method of oscillation, not here considered. 
 
 7. All our WEIGHINGS are made IN AIR; but air buoys up 
 all bodies to the extent of the weight of the air displaced by 
 the body on the scale pans. This is ARCHIMEDES’ principle, 
 applied to air. 
 
 Now, a cubic centimeter of air, under common conditions, 
 weighs one and one fifth milligrammes (1.2 mgr). For a fifty 
 gramme specific gravity flask, this amounts to 60 milligrammes 
 or 6 centigrammes.- This is evidently too much to be over- 
 looked. See 3, 12 and 38, Note. 
 
 8. Ordinary weights are made of turned brass, highly 
 polished or finely gilt (2, 7). The specific gravity or brass is 
 8.4; consequently the weights balancing 50 cc water occupy 
 about 6 cc, and therefore are buoyed up 7 mgr. 
 
 If we had actually 50 cc of water on the one pan, and 50 
 gramme weights on the other, there would be NO EQUILI- 
 BRIUM. The water would be buoyed up 60 mgrs., the weights 
 by 7 mgr; that is, equilibrium would be obtained by 49.947 
 grammes, showing an error of 53 mgr. for 50 cc of water. 
 
 9. In all accurate work, this buoyancy of the air must be 
 allowed for. This correction applied to the APPARENT 
 WEIGHT on the balance, gives the ABSOLUTE WEIGHT, 
 which the body would show, if weighed in vacuo. Hence this 
 correction is also called reduction to vacuum. For every 
 gramme, the correction amounts to the number of milligrammes 
 K given in the following table, varying with the specific 
 gravity G of the body weighed. These values are determined 
 
 as above. 
 
 Add. 
 
 Add. 
 
 Subtract. 
 
 (} 
 
 K 
 
 G 
 
 K 
 
 G 
 
 K 
 
 0.8 
 
 1.36 
 
 3 
 
 .26 
 
 9 
 
 0.01 
 
 I.O 
 
 1 .06 
 
 4 
 
 .16 
 
 10 
 
 .02 
 
 1.2 
 
 0.86 
 
 .S 
 
 .10 
 
 12 
 
 •05 
 
 1.4 
 
 0.71 
 
 6 
 
 .06 
 
 14 
 
 .06 
 
 1.6 
 
 0.61 
 
 7 
 
 •03 
 
 16 
 
 .07 
 
 1.8 
 
 0.52 
 
 8 
 
 .01 
 
 18 
 
 .08 
 
 2.0 
 
 0.46 
 
 8.5 
 
 .00 
 
 20 
 
 .09 
 
THE ANALYTICAL BALANCE, 
 
 221 
 
 Tlius 32.254 grammes of magnesium, G 1.75 give K 0.54 
 mgr. per gramme; the correction therefore is 17.4 mgr. and 
 the absolute weight 32.271 grammes. 
 
 10. It is true that this correction will fluctuate slightly 
 with the varying condition of the atmosphere as to tempera- 
 ture and pressure; but the latter CORRECTION OF THE 
 CORRECTION is an entirely insignificant quantity and there- 
 fore commonly disregarded. Minute quantities of second order 
 are always practically nothing. 
 
 11. If, for analysis, any suitable amount of the substance 
 has been taken, it is carefully dried (in the exsiccator, over 
 concentrated sulphuric acid) and then weighed (q). Now the 
 analytical operations are performed, the substance converted 
 into some new compound, and this weighed (p). Then the 
 ANALYTICAL RATIO a=p/q has been determined ; it is the 
 weight of the determined substance PER UNIT of the given 
 substance. A number of such determinations give a MEAN 
 VALUE representing the average result of all determinations. 
 
 12. Finally, this ratio is compared to the ATOMIC RATIO 
 r calculated from the chemical formula of the two substances 
 (the one taken and the one formed) with the accepted atomic 
 weights. If the analytical ratio agrees with the atomic ratio, 
 the substance is proved pure, 100 per cent, strong. Inversely, 
 if the substance had been prepared with utmost care, as pure 
 as possible, its analytical ratio agreeing with the atomic ratio, 
 demonstrates the correctness of the chemical formulas and the 
 atomic weights used. 
 
 Note. For any one series of analyses of the same given substance, 
 determining the same substance formed therefrom, the analytical ratio 
 must be constant; it may fluctuate slightly, according to the varying 
 imperfections of method and work, but it should not show any signs of 
 SYSTEMATIC VARIATION with the amount of substance taken. If it does, 
 such variation indicates a source of gravest error. 
 
 This is the case with the famous determinations of Stas (see p. 79). 
 Therefore, his conclusions are without foundation. 41, 12. 
 
47. SPECIFIC GRAVITY METHODS. 
 
 1. The physical methods of analysis (45.6) are all very 
 useful and interesting, but we have time for specific gravity 
 determinations only (2, 11, 12). These methods are both 
 practical and quite exact within their proper sphere. It 
 will be easiest to first consider liquids; the methods may 
 thereafter be readily applied to solids also. 
 
 2. THE GRADUATED CYLINDER weighed empty and 
 again when filled to any mark, gives both weight and volume 
 of the liquid; hence its G. Weighing to the decigramme, 
 estimating the volume to the tenth cc, it requires 20 to 40 cc 
 to obtain results worth calculating to two places.' The im- 
 portance of the method is its perfect clearness. It forms the 
 simplest and best introduction to specific gravity work. 
 
 3. THE LITER FLASK has a spherical form with cylindrical, 
 narrow neck, on which is the mark. The best flasks are pro- 
 vided with ground glass stopper; the bottom is flattened, the 
 glass thin and the flask light. 
 
 Weigh empty and filled to mark (3, 5) ; as the flask has a 
 definite capacity (10, 25, 50, 100 cc), all data are known. 
 The first practice consists in verifying the capacity of the 
 flask by using water, the temperature of which should be 
 observed and recorded. Weigh to centigramme. Calculate 
 three decimals. 
 
 4. THE PYKNOMETER or true specific gravity flask, is 
 usually provided with a ground glass stopper having a capillary 
 perforation. The filling must be done carefully. Flask only 
 handled by points of two fingers, at the neck. Weigh to the 
 milligramme; calculate G to four decimals. First use water 
 to test the capacity of the flask, and find the variations due 
 to changes in temperature. The Sprengel tubes are not re- 
 quired for this course. 
 
SPECIFIC GRAVITY METHODS. 
 
 223 
 
 '). In all these cases it is essential that THE VESSEL BE 
 CLEAN AND DRY before filling, and diy on the outside before 
 weighing. The latter is done by means of soft filter paper. 
 Working an aqueous solution exclusively, washing with water, 
 followed by careful filming (3, 3, Note) is sufficient. If 
 changing to another class of liquids, wash, rinse with water, 
 rinse with alcohol, film with ether and dry by a current of 
 air from a foot blower. ' 
 
 6. The specific gravity of SOLIDS, in fragments, is deter- 
 mined by cylinder, flasks and pyknometer, using water if the 
 solid is insoluble therein, otherwise some liquid (ether, ben- 
 zole), in which the solid is insoluble. Always take a relatively 
 large amount of solid, in comparison to the capacity of the 
 vessel ; this secures higher accuracy. Air bubbles must be 
 removed; glass rod or platinum wire may be used for that pur- 
 pose. 
 
 7. The solid having been weighed separately (w), also 
 the flask filled with liquid (a) and containing the solid with 
 liquid (b), we have evidently the loss w+a — b as the weight 
 of the liquid displaced by the solid. If the liquid be water, 
 then this is the volume v, and the specific gravity results by 
 the usual division. If not water, the gravity g of the liquid 
 must be determined; divided into the loss, the quotient will 
 be the volume v of the solid sought. Calculate as many dec- 
 mals as before directed. 
 
 8. Any balance is readily converted into our form of HY- 
 DROSTIC BALANCE by placing a crystallizing dish on the 
 bench over the left hand scale pan, suspending by a thin 
 platinum wire, a perforated platinum scale pan from the hook 
 into the water, all adjusted in such a manner that when the 
 beam is released, this submerged pan will be midway between 
 surface of the water and the bottom of the dish. On such a 
 balance, the body is weighed first in air (w), then in water 
 (a) ; evidently, w — a is the volume v, so that G can be calcu- 
 lated. Number of decimals depends on the character of the 
 balance. 
 
224 
 
 LECTURE 47. 
 
 9. No correction need be applied on account of the ex- 
 pansion of the glass vessels used; for this amounts to only 
 one forty-thousandth per degree. But the EXPANSION e OF 
 THE WATER per unit is notable, as given below in thousandths 
 (or units of third decimal). Since the standard is water at its 
 greatest density (4 degrees), the correction is the product 
 eG in the third place, which must be subtracted from G to 
 obtain the corrected G' referring to water at 4 degrees. 
 
 10. Expansion e of one cubic centimeter of water in units 
 of third place (thousandths) : 
 
 te te te te 
 
 o 
 
 0.13 
 
 16 
 
 1.03 
 
 30 
 
 4-3 
 
 70 
 
 22.7 
 
 4 
 
 0.00 
 
 20 
 
 1.77 
 
 40 
 
 7-7 
 
 80 
 
 29.0 
 
 8 
 
 0.12 
 
 24 
 
 2.68 
 
 ■ 50 
 
 12.0 
 
 90 
 
 CO 
 
 ro 
 
 12 
 
 0.47 
 
 28 
 
 3-79 
 
 60 
 
 17.0 
 
 100 
 
 43 -^ 
 
 Reduction to vacuum may be necessary also. Suppose the 
 division of volume into weight had given G 10.14-7 for silver 
 at 20 degrees; then e 1.77 times G gives 18 in third place, 
 hencs G reduced to 4 degrees is 10.129. 
 
 11. These methods are applied to the determination of the 
 strength of salt solutions, commercial and pure acids and 
 alkalies, sugars, which are heavier than water, also alcohol 
 and ammonia which are lighter. The specific gravity found, 
 generally reduced to water at 4 degrees, is looked up in the 
 tables of handbooks and the percentage of strength corre- 
 sponding hereto is taken from the tables. A simple IN- 
 TERPOLATION may be necessary to give the exact value if 
 the value of G is not in the table. Heavy metal solutions 
 should also be used, such as Ka lo-Hg^te. 
 
 12. Work on solids is suitably connected with the study 
 of important crystals, salts, metals, minerals and ores. Ordi- 
 nary specimens may be used in cylinder and flasks, the finest, 
 such as gems, cleavage pieces, rarer metals, are excellent for 
 determination by the hydrostatic balance. Carried on in this 
 manner, specific gravity work becomes as interesting as it is 
 practically useful. 
 
SPECIFIC GRAVITY METHODS. 
 
 Table. This short table gives the number of milligrammes 
 which a cubic centimeter of the following 10 per cent, solu- 
 tions weighs in EXCESS of one gramme: 
 
 
 Hate 
 
 Clide 
 
 Nate 
 
 Sate 
 
 Cate 
 
 H 
 
 0 
 
 49 
 
 58 
 
 68 
 
 — 
 
 Ka 
 
 92 
 
 65 
 
 64 
 
 (83) 
 
 92 
 
 Na 
 
 111 
 
 72 
 
 67 
 
 92 
 
 105 
 
 Clide: 
 
 Am 30, 
 
 Ca 86, 
 
 Ba 94, 
 
 
 ■Ag Nate 90 
 
 Sate: 
 
 Mg 105, 
 
 Cu 103, 
 
 Zn 108. 
 
 
 Pb Acet. 76 
 
 For about 5 per cent, either way, changes in G are pro- 
 portional to amount dissolved, and can be calculated readily. 
 Sucrose 40. 
 
 Lighter than water (mgr. less than 1 gr.) are for 10 per 
 cent, solutions: Ammonia 42, alcohol 14. 
 
 48. ANALYSIS BY DISSOCIATION. 
 
 1. Analysis by means of the physical agencies (45.7) and 
 without the use of reagents proper or change of vessel, is 
 necessarily capable of a HIGH DEGREE OF PRECISION. 
 Thus Richards, obtained in three series of electrolyses, 
 0.25455, 0.25450 and 0.25448 of metallic copper per unit of 
 blue vitriol; the mean is 0.25451. Precisely the same value 
 results by calculation from the formula Cu 0^5+5 H 2 O for 
 Cu 63.5, confirming this value. 
 
 2. Electrolysis having been considered sulficiently (35, 36, 
 37), we may devote this lesson mainly to DISSOCIATION, 
 that is, chemical decomposition by means of heat. If violent 
 and complex actions are avoided, this method of quantitative 
 analysis can furnish very accurate results, there being abso- 
 lutely no reagents used (hot even solvents as in electrolysis 
 in the wet way) and no change of vessels is necessary during 
 the process. 
 
 3. Another important excellency of this method we have in 
 the fact that the portion of matter, driven off by heat, can 
 
22G 
 
 LECTURE 48. 
 
 generally be collected for qualitative examination or for weigh-, 
 ing. Thus the dissociation may be CHECKED, both as to 
 kind and amount of the volatile substance driven off. 
 
 4. It is, however, necessary that the DEGREE OF HEAT 
 employed by reasonably constant and well selected. The 
 water bath, sand bath and air bath are sufficient to drive off 
 the more volatile constituents, such as water and many acids. 
 A dull red heat, just making the crucible glow, or a bright red 
 heat, may be maintained by a Bunsen Burner, properly regu- 
 lated. A real white heat requires the use of blast or furnace. 
 
 5 . THE SUBSTANCE to be analyzed must be pure, entire- 
 ly free from volatile impurities, such as humidity or hygro- 
 scopic water. Pulverization and drying over concentrated 
 sulphuric acid in the exsiccator, or in a current of dry air, are 
 commonly resorted to. Some crystallized bodies lose WATER 
 of crystallization by this means, unless the temperature is 
 kept low. Examination by the microscope will show efflor- 
 escence, if water is lost in this way. 
 
 6. Determinations of the WATER OF CRYSTALLIZATION 
 are especially interesting and instructive. The sand or air 
 bath will answer; temperature about 200 degrees. Gypsum, 
 blue vitriol, alum, borax, are a few of the more common cases. 
 The formulae are Ca O4S + 2 HgO; Cu O4S + 5 H2O; 
 Ka 204 S + Al2 (048)3+24 H2O; Naa B04 + 10 H.O; 
 they permit the calculation of the amount of water per unit 
 of weight (atomic ratio, 46 , 12 ) which will check the amount 
 actually obtained by the determination (the analytical ratio, 
 46 , 11 ). 
 
 7 . AT A RED HEAT, in a platinum or porcelain crucible 
 over a Bunsen flame, many important analyses by dissociation 
 are made. Blue vitriol leaves copper oxide, Cu O. Lead 
 nitrate Pb (03N)2 leaves lead oxide Pb O (in porcelain cru- 
 cible). Potassium bicarbonate, Ka H O3C leaves the carbon- 
 ate Ka2 O3C; of course, two atoms of the former yield one of 
 the latter. Potassium bitartrate Ka H C4H4O6 yields the 
 
ANALYSIS BY DISSOCIATION. 
 
 227 
 
 carbonate also. Crystallized Am-Mg phosphate Mg O 4 P + 
 G H 2 O yields Mg pyrophosphate, Mg 2 O 7 P 2 in all gravimetric 
 phosphate determinations. 
 
 8 . Dissociations requiring a WHITE HEAT necessitate the 
 use of the blast flame under the platinum crucible. The fire- 
 clay (Erdmann) or graphite cylinder around the crucible, facili- 
 tates the work. Examples are common, results quite accurate. 
 Calcite and any calcium carbonate CaOgC yields the oxide, 
 lime, CaO. Magnesium carbonate yields the oxide already 
 at a red heat. 
 
 9. In all cases, the determination involves the weighing of 
 the vessel, taking substance and weighing the vessel with the 
 substance; igniting, chilling on iron, cooling in exsiccator, 
 weighing; repeating this process TILL CONSTANT WEIGHT 
 OBTAINED, that is, no further loss sustained by renewed 
 ignition. In all cases, the analytical ratio obtained should be 
 compared with the atomic ratio calculated from the formula. 
 
 10. The most useful technical analysis of coal is a process 
 of dissociation, carefully worked out by the author in 1867 and 
 1868 (American Journal of Mining, New York, also in German 
 and English periodicals) have become part of general chemical 
 practice. The remarkable increase in weight when bitumin- 
 ous coals are dried for the determination of moisture, was dis- 
 covered in this research, and is due to oxidation of the bitumen 
 at low temperatures. 
 
 Notes. The student should, for practice, calculate the atomic ratios 
 for the cases specified, and compare the results with the following: 
 
 6. Gvpsum 0.7907. Blue Vitriol 0.6393. Ka-Alum 0.5443. 
 
 7. Blue Vitriol 0.3186. Lead Nitrate 0.6254. Ka Bicarbonate 0.6900. 
 Ka Bitartrate 0.3670. Am Mg Phosphate 0.4531. 
 
 8. Ca Carbonate 0.5600. Mg Carbonate 0.4762. 
 
49. GASOMETRIC ANALYSIS. 
 
 1. Gasometric Analysis has been DEFINED (45, 9) and 
 characterized (45, 5) ; we have also quite extensively prac- 
 ticed it (18, 8-11; 24, 7) and learned to distinguish it from 
 GAS-ANALYSIS (32; 33, 3-11; 45, 9). We shall now briefly 
 state OUR SPECIAL METHODS of reduction and work in this 
 fascinating and admirably simple process of analysis. 
 
 2. The law of Avogadro (40, 10) asserts that the molecular 
 volume of all gasps, at the same temperature and pressure, is 
 the same. For practical work, the milligramme is our unit of 
 weight; the mgr. molecule of hydrogen gas our unit of volume. 
 We disregard temperature and pressure by CHEMICALLY 
 DETERMINING THIS UNIT OF VOLUME EXPERIMENTALLY, 
 i. e. the volume occupied by the hydrogen produced from 24 
 mgr. magnesium. 
 
 3. This MGR. MOL. VL. is always nearly 24 cc at ordi- 
 nary pressures and temperatures, at which gasometric work is 
 done in the laboratory. That is, having dissolved an accur- 
 ately (to tenth mgr.) weighed amount of pure magnesium, 
 and measured the gas volume produced in cc, the quotient of 
 the volume, divided by the weight, differs by but a small frac- 
 tion from unity; say by e per cent. Then all volumes ob- 
 served in analysis, at the time, must be reduced that number 
 of per cent., to bring the volume to our standard. 
 
 4. Our ordinary GAS BURETTE is the simplest possible, 
 readily made from any Mohr’s burette and a pipette, as shown 
 in our plate of Apparatus. We also make use of the Hempel 
 gas burette with perforated stop cock, (3, 10, 11) but in 
 reversed position, and provided with pipette-reservoir; we 
 use this both with water and mercury. A simple water- 
 jacket, consisting of a glass tube surrounding the burette and 
 exceeding it about 6 m m in width, filled with water, suffices. 
 A thermometer is inserted in the pipette -bulb receiver. 
 
GASOMETRiC ANALYSIS. 
 
 229 
 
 5. OUR EVOLUTION VESSELS vary considerably, accord- 
 ing to the object for which they are used. The simplest is an 
 ordinary test tube, fastened by means of a cork in a cylindri- 
 cal stand glass but little wider, the space being filled with 
 water, while the test tube, by means of perforated stopper, 
 allows connection with the burette by rubber tube of small 
 bore. 
 
 We work the evolution at all temperatures, the only condi- 
 tion being that the temperature is the same at the final and at 
 the initial reading of the burette. 
 
 6. When necessary we insert between the evolution vessel 
 and the burette our AIR LOCK, simply a U-tube of proper 
 capacity (100 or 200 cc) having enough lead foil wrapped 
 around one branch to stay down in a tall beaker with water; 
 by judicious use of black paint, the lead sticks to the glass 
 and does not corrode. At the close of each determination, 
 after detaching the evolution vessel, a few motions of the reser- 
 voir thoroughly ventilate the air lock, filling it with atmospheric 
 air. The principle here used is that of displacement. 
 
 7. Gases acting upon air are handled IN ANY SUITABLE 
 GAS; thus nitric oxide in hydrogen. In such experiments the 
 Hempel burette is most serviceable, on account of that per- 
 forated stop cock. A Kipp and the necessary washing flasks 
 are connected with the evolution vessel, by means of a tube 
 with stop cock. 
 
 The determinations being very rapid, hydrogen does not 
 leak appreciably; but using an air lock connected by glass 
 tubing, even this error may be overcome entirely. 
 
 8. Under these conditions, the reduced gas (3 and 4 above) 
 weighs per cubic centimeter as many milligrammes as its 
 molecular weight divided by 24. That is, a cubic centimeter 
 of the following gases, after such reduction, weighs the num- 
 ber of milligrammes stated: H, 0.083 (iV) ; N, 1.1G6 (IJ); 
 O, 1.333 di) ; Cl, 2.958 (2|i) ; NO, 1.250 (1|) ; CO., 1.833 
 (Ij). UreaCH 40 N 2 , 2.500 (21). Sweet spirits of nitre, 
 3.125 (3i). 
 
230 
 
 LECTURE 49. 
 
 For solubility allow a volume equal to that of the liquid 
 used in the case of NO and CO 2 . 
 
 9. As to PROCESSES employed, hydrogen is produced by 
 acids and magnesium; carbon dioxide by acids and most car- 
 bonates; nitrogen from urea and a strong, fresh solution of 
 hypobromite; chlorine from hypochlorites or chlorine water 
 and peroxide of hydrogen; oxygen from permanganate and 
 peroxide of hydrogen ; nitric oxide from sweet spirits of nitre, 
 Ka lo’^^e and H in an atmosphere of hydrogen. The sub- 
 stance used as reagent must be in excess; in the last example, 
 there must be an excess of permanganate if the peroxide is to 
 be determined, while if permanganate is to be determined, an 
 excess of peroxide must be taken. 
 
 10. The QUANTITATIVE RELATION between the VOLUME 
 of the gas produced and the WEIGHT of the substance taken 
 must be carefully established before the process can be accep- 
 ted. The reaction must also be quick and complete. 
 
 For hydrogen, we obtain one equivalent for each equivalent 
 of metal dissolved. But this process, being fundamental, we 
 use to determine the unit or equivalent volume of hydrogen 
 itself, to make us independent of variations in temperature 
 and pressure. 
 
 11. Carbonates give one molecule of fixed air for each 
 double equivalent. Consequently, 100 mgr. Ka Bicarbonate 
 rnust yield 24 cc gas; or every cc gas represents 4.16 mgr. of 
 the true bicarbonate. Thus the percentage of pure bicarbon- 
 ate in the sample taken becomes known. In the same way, 
 each cc nitrogen gas representing 2.5 mgr. of urea, the gas 
 evolved from a measured quantity of urine gives its per cent, 
 of urea. Hypochlorites give a volume of oxygen gas exactly 
 equal to that of the effective chlorine; or 2 Ca OCl=183 
 yield one molecule O, hence every cc gas corresponds to 7.625 
 Ca hypochlorite. 
 
 12. It will readily be seen that this method of analysis has 
 received a considerable extension at our hands. Further 
 details will be given in the laboratory course. 
 
GASOMETRIC ANALYSIS. 
 
 231 
 
 As to CALCULATIONS, one example will suffice. Suppose 
 42.7 mgr. Mg gave 44.5 cc gas; hence 1 mgr. gave 1.042 cc; 
 reduction 4.2 per cent. 
 
 Peroxide of hydrogen, mixed with an equal volume of dilute 
 sulphuric acid; 5 cc mixture gave, with excess of permanga- 
 nate, 57.2 cc gas. The 4.2 per cent, is 2.4 cc, leaving 54.8 
 cc reduced; hence 10.96 vols. ; weight one and a third gives 
 14.61 mgr. oxygen per cc peroxide, or 1.46 per cent, by weight 
 of oxygen; or 3.1 per cent, peroxide, by weight. 
 
 Note. A cubic centimeter of dry air weighs 1.2 mgr. at the following 
 temperatures and pressure (mm) : 
 
 t I 5 9 13 17 21 25 29 
 
 p 710 720 730 740 750 760 770 7S0 
 
 The CHANGE in weight amounts to one per cent, for 3 degrees in tem- 
 perature and for 7 millimeters pressure. 
 
 By this simple table of reduction, the weight may be calculated from 
 the observed pressure and temperature. For example, at 18 degrees and 
 735 mm, we calculate from nearest 17 degrees 750, as follows: i degree 
 high, weight P®’'' cent, low; 15 mm low, weight 2 per cent, low; total 
 2^3 per cent, lovv, on 1.2 mgr. is 0.028 low, say 0.03: hence weight of one 
 cc air at 18 degrees and 735 mm is 1.17 mgr. 
 
 Same correction per cent, must be applied to weights given in 8 if this 
 mode of reduction by barometer and thermometer reading be preferred. 
 
 In this mode of reduction, it must be remembered that the vapor pre's- 
 sure must be subtracted from the reduced barometer reading to get the 
 pressure of the dry gas required. This vapor pressure is, in mm mer- 
 cury : 
 
 temp. 6 10 14 18 22 26 30 
 
 vap. press. 7.0 9.1 11.9 15.4 19.7 25.0 31.6 
 
 For chemical purposes, the reduction given in the text is both easiest 
 applied and most rational. 
 
 50. VOLUMETRIC ANALYSIS. 
 
 1. This excellent method of quantitative analysis has been 
 exemplified in lecture 24 for the measurement of acids and 
 bases. A general definition thereof has also been given 
 (45.10). This method of analysis was founded by GAY- 
 
232 
 
 LECTURE 50. 
 
 LUSSAC (1824 to 1832) and was brought into system by 
 MOHR (Titrir-Methode, 1855). We will now present the^ 
 leading principles and modes of practice of the same. 
 
 2. The two kinds of TEST SOLUTIONS introduced by these 
 chemists continue in use — each being most convenient in its 
 own sphere. When many determinations of the same kind 
 have to be made, the Gay-Lussac STANDARD SOLUTION, 
 representing a centigramme or milligramme of the substance 
 per cubic centimeter, is used. If a greater variety of work has 
 to be done by the least number of test solutions, the NORMAL 
 SOLUTIONS of Mohr are the most practical. 
 
 3. Silver, Ag=108 is precipitated by salt, Na Cl=58.5; 
 accordingly the atomic ratio of silver to salt is 1 : 0.5417. A 
 cubic centimeter of salt solution will therefore precipitate one 
 milligramme of silver, if it contains 0.5417 mgr. salt per cc, or 
 0.5417 grammes per liter. A cubic centimeter of salt- solution 
 will precipitate a centigramme of silver, if it contains 5.417 
 grammes of salt per liter. Such solutions are standard solu- 
 tions according to GAY-LUSSAC; the number of cubic centi- 
 meters used directly gives the weight of the silver or substance 
 sought. 
 
 4. The normal solutions of MOHR contain a milligramme - 
 equivalent per cubic centimeter (24.6 and 45.10). A normal 
 salt solution therefore is made by dissolving 58.5 grammes of 
 pure sodium chloride to a liter; and each cubic centimeter 
 thereof will precipitate one milligramme-equivalent of silver, 
 that is 108 mgrs. A tenth -normal salt solution is made dis- 
 solving 5.85 gr. salt to a liter, and each cc thereof precipitates 
 10.8 mgr. silver. 
 
 5. The Mohr solutions can also be used to determine the 
 PER CENT. STRENGTH of any given substance, without 
 calculation, by WEIGHING OFF A PROPER QUANTITY, de- 
 termined by the equivalent weights. Thus if each cc of the 
 tenth normal solution is to represent one per cent., the total 
 100 per cent, silver must equal 100 cc tenth normal or 10 
 
VOLUMETRIC ANALYSIS. 
 
 233 
 
 normal = 10 times 108 mgr. = 1.080 grammes of silver. If 
 this amount of silver (alloy) is dissolved, it will require as 
 many cc tenth normal salt solution as it contains per cent, of 
 pure silver. In general, take 100 mgr. equiv. and 1 per cent, 
 will be precipitated by 1 cc N solution. 
 
 6 . We have now presented really all principles required in 
 the calculation of volumetric work. Suppose the strength of 
 aqua ammonia were to be determined by normal acid in per 
 cent, of ammonia gas, NH 3 = 17. Then 100 cc normal would 
 contain 1700 mgr. NH3 = 1.7 gramme. Take 1.7 grammes of 
 the aqua ammonia, and neutralize with normal acid; the num- 
 ber of cc used evidently are the per cent. NH3 gas in the 
 liquid. If half the quantity be taken, every cc normal acid 
 represents 2 per cent. 
 
 7. Of the principal lines of volumetric work, NEUTRALI- 
 ZATION has already been considered (Lect. 24). In practice, 
 each cc of normal acid measures an equivalent amount of 
 alkali ; that is, one mgr. equiv. In numbers, 17 mgr. ammonia ; 
 40 mgr. NaHate (NaOH); 56 mgr. Ka Hate (KaOH). In the 
 same way, each cc normal alkali measures one mgr. equiv. of 
 any acid. In numbers, 63 mgr. nitric (HO 3 N) ; 49 mgr. sul- 
 phuric 4 (H 204 S). 
 
 8 . THE CHAMELEON PROCESS has been considered so 
 far as to show that every 2 atoms of the reagent (Ka O 4 Mn, 
 = 158) set free 5 atoms of oxygen (10 equivalents) ; or 1 mgr. 
 equivalent oxygen corresponds to 31.6 mgr. of pure permanga- 
 nate. Tenth -normal requires 3.16 gr. per liter. 
 
 The standardizing is done with the pure, crystallized 
 hydrated ammonio-ferrous sulphate, Am 204 S + Fe 04 S -|- 
 6 H 2 O = 392 (see 15, 11). Two of this salt require one atom 
 of oxygen (see 44.9) hence 39.2 is tenth -normal. In the 
 presence of a large .excess of sulphuric acid, the reaction is 
 quick and sharp. Add permanganate to acid ferrous solution 
 till color no longer disappears. The so-called “florist’s wire” 
 generalfy used for standardizing, is not pure iron. 
 
234 
 
 LECTURE 51. 
 
 9. THE IODINE PROCESS, due to Bunsen (p. 24) is typi- 
 fied in the reaction between the HYPO and the iodine solution; 
 using a trifle of starch paste as indicated (BLUE with smallest 
 trace of FREE iodine, 23, 4). Pure, crystallized Na Hyposul- 
 phite is represented by NasOgSa+S HgO = 248. Two of this 
 THIOSULPHATE react with two iodine, giving two Na lo and 
 the so-called tetrathionate NaaOeSi; hence 248 hypo corre- 
 spond to 127 iodine. Tenth -normal hypo must contain 24.8 
 mgr. per cc, and is equivalent to 12.7 iodine, or 8.0 bromine, 
 or 3.55 chlorine. The iodine is kept in solution by an excess 
 of Ka loide — best twice the weight of the iodine. Twentieth 
 normal is more convenient for use. 
 
 10. PRECIPITATION of neutral chloride by silver permits 
 
 the use of Ka Cr^te as indicator; when all precipitated 
 
 as Ag the next drop will show the red color due to 
 
 Ag Crate (Mohr). 
 
 A tenth -normal Ag Nate solution is obtained by dissolving 
 17 grammes of the nitrate (Ag O 3 N = 170) to the liter. Every 
 cc hereof will represent the following equivalents: 5.85 mgr. 
 Na Cl; 15.0 mgr. Na lo; 7.45 mgr. Ka Cl; 16.6 mgr. Ka lo; 
 8.7 mgr. Li Br; 15.5 mgr. Fe loa. These data are easily 
 calculated from the formulas given. 
 
 51. GRAVIMETRIC ANALYSIS. 
 
 1. In gravimetric analysis, a weighed amount of the sub- 
 stance is chemically changed to some well-defined compound, 
 sufficiently permanent to permit accurate weighing. The 
 chemical formula of this compound will tell how much it con- 
 tains of the ingredient to be determined. Thus the amount 
 in a UNIT OF WEIGHT of the original substance becomes 
 known. See 45, 11 . 
 
 2. Suppose that the amount of CALCIUM in a given sub- 
 stance were to be determined. The weighed substance 
 is dissolved in acid, filtered; heavy metals removed, if 
 
GRAVIMETRIC ANALYSIS. 
 
 235 
 
 present; filtrate made ammonical and the calcium precipitated 
 as oxalate, that being the most insoluble d'alcium compound. 
 Filter, wash, dry on water bath, weigh the crystallized oxalate, 
 Ca O 4 C 2 + H 2 O = 146. In platinum crucible, at dull red- 
 ness, it changes to carbonate, Ca OsC^ 100, which weigh. 
 Ignite with blast at white heat; it becomes the oxide (or lime) 
 Ca O = 56, which weigh. 
 
 8 . From the formula given it is easy to CALCULATE that 
 a unit of weight of crystallized oxalate represents 0.2740 of 
 Ca, the carbonate 0.4000 and the oxide 0.7143 of Ca. In a 
 like manner the oxalate represents 0.3836 of oxide and the 
 carbonate 0.5600 thereof. If then, any of these compounds 
 found had been weighed, the corresponding amounts of Ca or 
 of Ca O is readily calculated by the values just given. In 
 this way the percentage in the original substance becomes 
 known. 
 
 4. Now, which of these compounds gives the MOST AC- 
 CURATE RESULTS.^ Not the oxalate, for it is difficult to avoid 
 a loss of water of crystallization in drying the precipitate; not 
 the carbonate, for overheating reduces it to oxide, insufficient 
 ignition may leave some oxalate. Evidently, the oxide, ob- 
 tained last is the best compound to use, for it need only be 
 ignited till constant weight, since it is not volatile at all. 
 
 5. We have already shown that SILVER is weighed as 
 CHLORIDE (45, 11). It need hardly be added, that chlorides 
 are determined in the same way, by the same compound, upon 
 adding an excess of silver solution. 
 
 The calculations are based upon the formula Ag Cl=143.5. 
 Every 143.5 Ag Cf^® weighed represent 108 silver in the 
 original ; or the weight of Ag Cn^® found, multiplied by 0.7525, 
 will give the weight of the silver. 
 
 6 . In the same manner the exceedingly insoluble Ba 
 
 is formed and weighed for the determination of the amount of 
 sulphate— by adding Ba solution; and for the determination of 
 barium— by adding a soluble sulphate. To obtain accurate 
 
236 
 
 LECTURE 51. 
 
 results, the MINUTl.^ of the operation must be studied and 
 practiced; precipitation, washing, igniting, in fact, every 
 operation has to be as nearly perfect as possible in order to 
 obtain reliable results. 
 
 7. Another compound of great importance in gravimetric 
 analysis, is the crystallized hydrated ammonio- magnesium 
 phosphate, almost absolutely insoluble in ammoniacal (CHde 
 and Hate) solutions. After filtering and washing it is dried, 
 ignited and weighed as magnesium pyrophosphate (48.7). 
 The Mg2 O7 P2=222 represents Pg 05=141 of the so-called 
 anhydrous phosphoric acid and 80 of Mg O. That is, 0.6351 
 thereof is P2 O5 and 0.3603 is magnesia, either of which is 
 so determined. 
 
 8. The metals may often be determined as oxide. Thus 
 iron compounds are generally determined as ferric oxideFea O3 
 =160. Ferric salts are directly precipitated by ammonia, 
 filtered, washed, ignited and weighed; ferrous are readily 
 oxidized with nitric acid to ferric, and treated as just stated. 
 Since Fe 0=72, 160 ferric oxide correspond to 144 ferrous 
 oxide and to 112 iron. By these numbers the reductions 
 necessary can be made. 
 
 9. Platinum chloride gives a crystallized precipitate of Am 
 CIO ptate ^ith sal-ammoniac, especially when alcohol present. 
 This salt, Amg Cle Pt=443 represents 36 ammonium and 194 
 platinum; ignited, it leaves only the latter, which thus repre- 
 sents 36 ammonium or 34 ammonia gas. This is only 0.0767 
 of the crystallized salt, thus may serve for accurate determi- 
 nations. 
 
 10. The subject of quantitative analysis is as difficult as it 
 is important. While only laboratory work will make these 
 processes thoroughly understood and familiar, it is hoped that 
 these carefully selected examples will suffice to make the stu- 
 dent comprehend the methods employed and the value of the 
 results obtained. While an application of chemical formulas, 
 quantitative analysis really is equally demonstrating the truth 
 of the chemical formulas themselves. 
 
52. SPECTRUM ANALYSIS. 
 
 1. The rainbow shows a SPECTRUM of sun light. Look- 
 ing through a prism at any narrow band of white, we see a 
 corresponding series of colors. The least deflected from the 
 straight line of sight, is the red; then comes orange, yellow, 
 green, blue, indigo and violet, which is the most deflected. 
 Newton (1671) first thoroughly studied the solar spectrum 
 obtained through glass prisms. 
 
 2. In these spectra the colors blend and overlap. Narrow- 
 ing the band of light — by means of an adjustable slit in the 
 shutter of a darkened room — the colors become more distinct 
 and pure, but at the same time, the total intensity becomes 
 less. By observing through a telescope, more light enters the 
 eye, the pupil of which is thereby virtually enlarged to the 
 size of the object glass of the telescope. This was first done 
 by Fraunhofer of Munich (1814). He obtained the best de- 
 fined spectrum of the sun, the purest and most brilliant. But 
 he was surprised to find many parts of the spectrum missing — 
 replaced by fine black lines, the so-called FRAUNHOFER 
 LINES of the spectrum. He counted thousands. The most 
 notable he designated by the letters of the alphabet from A to 
 H ; groups of lines he marked a, b. See upper spectrum, p. 72. 
 
 3. For greater convenience, Kirchhoff (p. 35) and Bunsen 
 (p. 24) combined all these pieces of apparatus on one frame, 
 and called the instrument resulting, a SPECTROSCOPE (1860). 
 For ordinary chemical work, the DIRECT VISION spectroscope 
 is the most convenient. It has the narrow, adjustable SLIT 
 turned towards the light. Then comes a powerful SYSTEM 
 OF PRISMS (of 3 crown and 2 flint glass prisms) ; finally a 
 small telescope. All these parts are enclosed in one tube. 
 
 4. Looking through such a spectroscope at the sky, first 
 narrow the slit till almost shut, then slide the telescope in or 
 out till distinct vision of the Fraunhofer lines. The black line 
 
238 
 
 LECTURE 52. 
 
 D in the yellow, and the line E in the green near the group b 
 will be readily recognized. The instrument is now ADJUSTED 
 for chemical work. — It is best to revolve the spectroscope till 
 the spectrum appears horizontal with the red to the left, as 
 they are conventionally represented in spectrum plates (p. 72) . 
 
 5. Looking at the colorless flame of a Bunsen Burner, it 
 will be almost invisible; a yellow line may flash up from time 
 to time, due to traces of sodium almost everywhere. Intro- 
 ducing a clean (ignited till imparting no color to flame) plati- 
 num loop that has touched a sodium compound or solution, a 
 brilliantly luminous line will flash up in the yellow. If the 
 Bunsen flame is so placed that good daylight can enter the 
 spectroscope through the flame, the solar and the sodium 
 spectrum will be seen simultaneously. The yellow sodium 
 line is then seen to coincide with the line D. There is sodium 
 in the sun. 
 
 6. The spectra of the elements which can be observed in 
 this manner, using the heat of the Bunsen flame only, are 
 mapped on page 72. The most characteristic bright lines are: 
 extreme red for Ka; brilliant red (near C) Li; blue line 
 (beyond F), Sr; brilliant orange, yellow and green line, Ca; 
 group of 3 or 4 bright green lines, Ba. By the two lines in 
 the violet, Bunsen recognized the NEW ELEMENT rubidium 
 (Rb). By the two lines in the blue, he found caesium (Cs). 
 The extremely bright, but very transitory line in the green, 
 revealed Thaltium (Tl) to Crooks of England and Lamy of 
 France. 
 
 7. By means of the electric sparks of a Ruhmkorff coil, the 
 heavy metals are volatized in minimal quantities, but sufficient 
 to show their spectra brilliantly. These spectra are too com- 
 plex, consist of too many lines, to be useful in ordinary chemi- 
 cal practice. 
 
 The discharge of the coil through rarified gases (in Pluecker 
 tubes, contracted in the middle) gives fine line spectra for 
 ready chemical identification. The hydrogen spectrum con- 
 sists of a red and a blue line, coinciding with the Fraun- 
 
SPECTRUM ANALYSIS. 
 
 2:^9 
 
 hofer C, F and a violet line near G. By its spectrum, argon 
 is distinguished from nitrogen (38, 10). 
 
 8. At lectures, before the general public, many of these 
 phenomena are projected on the screen. For scientific stu- 
 dents it is preferrable to show these phenomena individually 
 at an EXHIBITION, where the different instruments are in 
 charge of one or two students each, who, by their advanced 
 work in the laboratory, have bocome familiar therewith. This 
 is the only way to show the flame and gas spectra in their 
 real beauty. 
 
 9. Twenty years ago, a line in the spectrum of the solar 
 corona was discovered, on the absolute or wave length scale 
 at Dg =587.5, near the Na line, which shows double in such 
 powerful instruments, at 02=588.9, and Di=589.5. No ter- 
 restrial element showing that line, it was ascribed to some 
 hypothetic element peculiar to the solar corona, and named 
 Helium. 
 
 10. When Lord Rayleigh had discovered argon in the air. 
 Professor Ramsey, searching for mineral sources of argon, found 
 a gas, giving the characteristic Dg line, on treating Cleveit 
 with sulphuric acid (1895). This gas is that substance 
 of the solar corona called Helium. Its density is twice that of 
 hydrogen, its atomic weight is taken at 4. Like argon, it is 
 nullovalent, does not combine chemically. One gramme of 
 cleveit (a rare Uranium mineral) gives about 7 cc helium gas. 
 It has also been found in rare Yttrium minerals (Fergusonite, 
 Samarskite) . 
 
 11. If a direct vision spectroscope be substituted for the 
 eye piece of a telescope, the spectra of the stars and nebulae 
 can be observed, as well as the spectrum of any part of the 
 sun, its, spots, protuberances and other details. Huggins, 
 Janssen, Lockyer and others have developed this part of 
 astronomy which may be considered as COSMICAL CHEMIS- 
 TRY. Father SECCHI (p. 29) has labored most successfully 
 in this field, and first classified the stars according to their 
 
240 
 
 LECTURE 53. 
 
 spectra, i. e. their chemical composition. The telescope of 
 Galilei showed the form (p. 44) while the spectroscope reveals 
 the chemical nature of the stars. 
 
 12. When tne spectroscope is directly against the bright 
 sky so as to show the solar spectrum well, a test tube, con- 
 taining a dilute solution of any coloring material, held before 
 the slit, will blot out parts of the spectrum, sometimes show- 
 ing definite black lines. These spectra are called ABSORP- 
 TION SPECTRA. The spectra of chlorophyll, red blood 
 (arterial) and blue blood (veinous) are quite characteristic. 
 These absorption spectra are most useful to organic chemistry. 
 
 53. DRY WAY ANALYSIS. 
 
 1. After having shown how the chemical formulae of com- 
 pounds are established and applied for quantitative determina- 
 tions, we will complete the introduction to the inorganic part 
 of chemistry by a systematic exposition of the principal 
 QUALITATIVE TESTS, both in the dry and the wet way. 
 This course we have found much more interesting and useful 
 than a synopsis of systematic chemistry. 
 
 2. The chemical blowpipe has been described (Lect. 5) 
 and its use has been frequently required (Lectures 5, 6, 7, 9, 
 10, 11, 18, 26). We have learned to appreciate the blowpipe 
 reactions (PYROGNOSTICS) because they require but a small 
 instrument and a few of the simplest reagents, while giving 
 definite results quickly and with but little labor — provided 
 some skill has been acquired. All the typical tests can 
 be well shown at lectures, so that even those who do not 
 practice themselves will quite well understand the subject. 
 
 3. THE FIRST TEST is made by heating a minute sample 
 on charcoal. The general results to be looked for are: 1, com- 
 plete VOLATILIZATION, with or without odor; 2, a RESIDUE 
 (i. e. where the substance was placed), and noting whether 
 this residue is WHITE or NOT WHITE, also whether it pro- 
 
DRY WAY ANALYSIS. 
 
 241 
 
 duces FLAME COLORATION. Next look for an INCRUSTA- 
 TION, i. e. deposit forming at some distance from the sample; 
 and lastly, look for a REGULUS. Compare diagram, p. 73 
 (dry way) . 
 
 4. If the substance volatilizes completely, repeat the ex- 
 periment and examine carefully whether an ODOR can be 
 recognized; that of burning sulphur proves S; of garlic, some 
 As compound. If no odor, heat the substance with lime in a 
 blowpipe glass tube; a distillate of white, metallic globules 
 proves an Hg compound; odor of ammonia, an ammonium 
 compound. 
 
 5. If the RESIDUE IS WHITE, it may show a) FLAME 
 COLORATION or simply be an incandescent b) INFUSIBLE 
 mass. In the first place (a) repeat the test on the platinum 
 loop: flame yellow, Na; yellowish-green, Ba; orange, Ca; 
 crimson, Sr; violet-purplish, Ka. Of these flames, Na, Ba, 
 Ca are invisible through blue glass, through which Ka, Sr 
 show finely; while these are invisible through a green glass 
 which shows Na, Ba, Ca well. In (b) ignite after adding a 
 drop of Co solution; color pale rose. Mg; green, Zn; blue, 
 A1 (see 7, 9). 
 
 G. If an INCRUSTATION has formed, note its color, size, 
 and see whether there is also a regulus. Incrustation WHITE; 
 very large, odor of garlic. As; smaller, nearer sample, with 
 brittle regulus, smoking, Sb; white when cold, yellow while 
 hot, Zn (try Co solution) ; YELLOW with brittle regulus, Bi, 
 with malleable soft regulus, Pb; YELLOWISH, close to sample, 
 regulus difficult except with cyanide flux, Sn; BROWN, no 
 regulus, Cd; pale red, very light in amount, with fine white 
 globular regulus, Ag. 
 
 7. A REGULUS WITHOUT INCRUSTATION may appear as 
 GLOBULE (Cu, Ag, Au, see 7, 1-3) or as SPANGLES. In the 
 latter case, the metal is generally not visible, except after 
 cutting out the charcoal, grinding it under water in an agate 
 mortar, and washing the light carbon particles off; the heavy, 
 metallic, now partly flattened grains and spangles, will remain 
 
242 
 
 LECTURE 53. 
 
 at the bottom of the mortar. Pt, Ir, Pd are white, hard, very 
 heavy, insoluble in acids; Fe, Ni, Co, are gray and magnetic. 
 See 7, 11. 
 
 8. If no incrustation, no regulus, no white residue, but only 
 a DARK COLORED residue remains, touch it with a good 
 BORAX BEAD and fuse again. If the bead is BLUE, hot or 
 cold, outer or inner flame, Co; if DEEP GREEN under all con- 
 ditions, Cr; if hot green, cooling turns blue, Cu; BROWN, 
 Ni; AMETHYST in outer, colorless in inner flame, Mn; YEL- 
 LOWISH to ORANGE in outer, colorless or very pale green in 
 inner flame, Fe. Compare 7, 11. 
 
 9. MICROCOSMIC SALT, NaAmH O 4 P + 4 H 2 O, when 
 heated in the platinum loop, becomes metaphosphate Na O3P 
 which, like borax, dissolves metallic oxides and gives colored 
 beads. We use these beads exclusively to recognize silicates 
 and the chloroid compounds. The first leave an insoluble 
 SKELETON OF SILICA (10.5; 11, 4) floating in the melted 
 bead. To test for the latter, first saturate the bead with 
 copper oxide, then add a trifle of the substance to be tested; 
 flame colorations: blue, Cf^®; blueish green. Bride; intense 
 green, loide. Bead heated in glass tube, making inside dim 
 (after washing) , Ffde. 
 
 10. SULPHATES, when mixed with pure soda and fused on 
 platinum loop in inner flame, are reduced to sulphides; the 
 fused mass placed on a silver coin, with a drop of water, 
 blackens the silver, at least if a trace of muriatic acid is added 
 (HEPAR reaction). SULPHIDES give the odor of burning 
 sulphur (9.3). NITRATES and CHLORATES deflagrate on 
 charcoal, the latter especially violently. CARBONATES are 
 best recognized by effervescence with an acid. BORATES 
 tinge the flame green on its outer edges, especially on adding 
 a drop of HFl-Si^te. These are the principal pyrognostic re- 
 actions. Oxides give no reactions as negatives; they are 
 recognized by their physical properties after other negatives 
 are proved absent. 
 
54. WET WAY ANALYSIS OF BASES. 
 
 1. In lecture 22 the metals were separated into 8 analyti- 
 cal groups, mainly by the use of hydrogen sulphide gas, and 
 each metal was individually recognized by the specific peculi- 
 arities of the group reaction. We need only to add the most 
 important DISTINCTIVE TESTS and a few specially delicate 
 tests whereby TRACES of the metals may be detected. 
 Methods of SEPARATION will also be indicated. We take up 
 the metals by analytical groups. 
 
 2. THE GOLD GROUP is precipitated by H in acid 
 solution, the precipitate is soluble in yellow ammonium sul- 
 phide; the original solution is yellow to brownish. 
 
 GOLD is precipitated as metallic powder by a ferrous solu- 
 tion (best the ferrous salt, 15, 11); the precipitate appears 
 brown in reflected, bluish in transmitted light; the dried pre- 
 cipitate shows metallic luster when pressed with a knife blade. 
 Platinum is not precipitated by this reagent, except upon 
 boiling. 
 
 PLATINUM solutions, when not too dilute, and containing 
 H Glide* yield a yellow precipitate with Am Cfde, forming 
 splendid transparent yellow octahedral crystals, which can be 
 studied under the magnifier or the microscope. Ignition leaves 
 Pt sponge. 51.9. 
 
 3. THE ARSENIC GROUP is distinguished from the gold 
 group by its solutions being colorless. The dry way reactions 
 are especially valuable (53, 4, 6). The most sensitive test 
 for ANTIMONY is given 37, 5; its solutions are also noted for 
 giving a white turbidity with water, which promptly dissolves 
 upon the addition of tartaric acid. Stannous solutions are 
 precipitated white by mercuric chloride; stannic solutions not. 
 Stannous solutions, containing a little stannic, (on addition of 
 Cl -water) give purple of Cassius with gold solutions. Fur- 
 ther special tests for As belong to toxicology. 
 
244 
 
 LECTURE 54. 
 
 4. THE COPPER GROUP is precipitated by hydrogen sul- 
 phide in acid solutions, and the precipitate is insoluble in yel- 
 low ammonium sulphide. Only Cu is slightly soluble in 
 this solvent. 
 
 Am Hate precipitates all ; the white precipitates of Hg’c and 
 Bi are insoluble in excess; the blue precipitate of copper dis- 
 solves to sky blue solution, the white precipitate of cadmium 
 dissolves to colorless solution with excess. 
 
 The hydrates precipitated by Ka Hate are all insoluble in 
 excess; Cd, Bi white, Hgic brown, with excess yellow and 
 in presence of ammonia, white; Cu, light blue, on boiling 
 black. 
 
 The iodides, see 23, 11. Wet way reductions (20, 6) show 
 best in reflected light under the microscope: Bi acicular gray, 
 Cd mosslike gray; Cu mosslike red crystals. See also pyro- 
 gnostics. 
 
 Bi solutions give white turbidity with water, not soluble in 
 tartaric acid, only soluble in mineral acids. Copper solutions, 
 even if extremely dilute, give a brownish precipitate with Ka 
 Cyo Feate solutions. 
 
 5. THE SILVER GROUP reacts towards H Side and yellow 
 ammonium sulphide exactly as the copper group, from which 
 it differs by being precipitated by H CPde or any other soluble 
 chloride. See 22, Note 1. Iodides, see 23, 11. — Ka Crate 
 precipitates Ag deep purplish red; Hgous brick red; Pb bright 
 yellow, soluble in Ka Hate, but difficultly soluble in dilute nitric 
 acid. Ka Hate precipitates the hydrates: Ag, light brown, 
 Hgous black, both insoluble in excess (Ag Hate soluble in aqua 
 ammonia to explosive compound) ; Pb white, soluble in excess, 
 no immediate precipitate in presence of acetic acid. Pyrog- 
 nostic, see 53. — Wet way reductions, very fine: Ag, arbor- 
 escent, white crystals; Pb, acicular gray crystals; Hg, on 
 copper, silvering, volatilized by heat. 
 
 G. The zinc group is not precipitated by H Side gas in 
 acid solution, but like the aluminium group, precipitated there- 
 by in alkaline solutions; it is distinguished from the aluminium 
 
WET WAY ANALYSIS OF BASES. 
 
 245 
 
 group by its hydrates being soluble in sufficient Am solu- 
 tion. The pyrognostic tests on charcoal and borax beads are 
 specifically distinctive (Lect. 53). Mn on soda bead, GREEN 
 mass (manganate) dissolves in acid solution to purplish per- 
 manganate. 
 
 Potassium hydrate precipitates all, an excess dissolves Zn 
 only; from this solution, H reprecipitates the Zn, but Am 
 Cl'de does not (distinction from Al). The Mn precipitate, 
 white, turns dark brown; Feous white, turns promptly green- 
 ish, then rust brown; Ni light green, unchanged, dissolved by 
 Am to greenish blue solution; Co, blue precipitate, turns 
 green, on boiling reddish, is soluble in Am to brownish 
 red solution. 
 
 Feous solutions, even if extremely dilute, are precipitated 
 deep blue by Ka Cy' Fe^t© (red prussiate of potash), while 
 the Ka Cyc» Fe^te (yellow prussiate) give bluish white pre- 
 cipitate, turning gradually deep blue in air. 
 
 7. THE ALUMINIUM GROUP is characterized as just stated 
 
 under 6, its hydrates being insoluble in Am The pre- 
 
 cipitate with H Sid® in alkaline solutions is the hydrate, not a 
 sulphide. See 22, 10. 
 
 Ka Hate gives a precipitate in all cases: Al, white, readily 
 soluble in excess, reprecipitated by Am Cbde, not by H Side 
 (distinction from Zn) ; Ci'i® greenish, soluble in excess, repre- 
 cipitated by Am Cbde OR by protracted boiling; Feic> brown 
 precipitate, not soluble in excess. — See Pyrognostic reactions, 
 Lect. 53, and group tests, Lect. 22. 
 
 Ferric solutions, even if extremely dilute, give with Ka Cy® 
 Feate the deep blue precipitate (Prussian blue), insoluble in 
 H Clide, readily soluble in Ka Hate — With Ka Cyi Feate, no 
 precipitate. With Ka S-Cyate, deep blood red coloration, 
 destroyed by Ka Acetate, restored by H Cbde; color dissolved 
 in ether. Extremely sensitive reaction. Cr compounds, 
 fused with soda and nitre on loop, give chromate, yellow. 
 
 8. THE BARIUM AND MAGNESIUM GROUPS remain in 
 solution, if the treatment with H Sate (Lect. 22) has been 
 
246 
 
 LECTURE 55. 
 
 omitted. In the case of mixtures, it is best so to do; but in 
 case of presence of phosphates, the previous precipitation as 
 sulphate has advantages. 
 
 If no sulphate has been added, the second group (Ca, Sr, 
 Ba) is precipitated as in the first reaction of VIII; the 
 precipitate removed by filtration, the precipitate may be tested 
 for members of second group by flame (53, 3) and spectrum 
 (52, 6) while the filtrate is worked up as directed in Lect. 22, 
 Note 5. 
 
 9. THE PRESENCE OF PHOSPHATES, oxalates, silicates, 
 borates and fluorides, singularly complicates the analytical 
 separation of the last two groups (our II and Vlll). When the 
 solution is made alkaline, previously to the precipitation of the 
 zinc and aluminium groups, such phosphates, etc., of the 
 barium group go down, and will be found in the precipitate of 
 VI, VII. By means of Ba a separation is effected, but 
 the operations are too complicated for the present. 
 
 10. SEPARATION of the different groups is effected by the 
 group reactions given. Separation of members in a group 
 depends on the individual characters given in this lesson. 
 Thus Fe’*^ is separated in VII from A1 by Ka H^te; Cd and Cu 
 from Hgic and Bi in III by excess of Am Hate; pb from Ag 
 and Hgous in I by water, and Ag from Hgous in the washed 
 precipitate by Am Hate. Such work, however, is specially 
 restricted to the Laboratory Stands. 
 
 55. WET WAY ANALYSIS OF ACIDS. 
 
 1. Having found the metallic constituent (27.5) in the 
 given compound, the known SOLUBILITY of the compound 
 examined will often enable us to exclude quite a number of 
 acids or non-metallic constituents, so as to limit our search to 
 those possibly present. 
 
 2. Thus, if LEAD has been found in a compound soluble in 
 water, it cannot possibly be the carbonate, sulphate, chro- 
 
WET WAY ANALYSIS OF ACIDS. 
 
 247 
 
 mate, sulphide, oxide, chloride, iodide; for these lead com- 
 pounds are all insoluble in water, as may be remembered from 
 previous lessons. If the lead compound examined had been 
 insoluble in water, any of the above acids might be present, 
 but nitrate and acetate could not be, since lead nitrate and 
 acetate are soluble in water. 
 
 3. Accordingly it is important to be able to tell what com- 
 pounds are soluble in water, and which are insoluble therein. 
 For neutral compounds, the following simple RULES OF SOL- 
 UBILITY will answer all practical purposes: 
 
 4. SOLUBLE are nearly all the salts of Na, Ka and Am; 
 also Nitrates, Chlorates and Acetates. 
 
 SOLUBLE are the Carbonates, Phosphates, Silicates and 
 Oxalates of Na, Ka and Am. 
 
 SOLUBLE are the Hydrates, Oxides and Sulphides of Na, 
 Ka (Am) and Ca, Sr, Ba. 
 
 INSOLUBLE are the Sulphates of Ca, Sr, Ba and Pb; the 
 Chromates of Ba, Pb, Ag, Hg, Bi. 
 
 INSOLUBLE are the Chlorides of Ag, Hgous pb; also the 
 Iodides of same and of Hgic and Bi. 
 
 5. Those non-metallic constituents which yield a gas 
 (effervesce) upon the addition of a non-volatite acid, will 
 have been detected while testing for groups I and II (p. 146). 
 If the effervescence is odorless, and yields turbidity with lime 
 water, it is a carbonate. If the effervescence exhibits the 
 odor of burning sulphur, it is a sulphite; rotten eggs, a sul- 
 phide; peach blossoms, a cyanide. 
 
 G. Chromates, Manganates, Permanganates, Arsenates 
 and other salts containing a heavy metal and forming ME- 
 TALLO-SALTS reveal themselves by a separation of sulphur 
 (p. 146.3) when the acid solution is saturated with hydrogen 
 sulphide gas. At the same time, the color of the solution 
 often changes. Thus Chromates, being yellow or red, change 
 to green; Manganates are green and turn brownish; Perman- 
 ganates turn from purplish to brownish. 
 
248 
 
 LECTURE 55. 
 
 7. If the non -metallic constituent has not been indicated 
 
 by these reactions made in the course of examination for the 
 metal, the following REAGENTS are used: Ba N^te, Ca S^te 
 and Ag detecting respectively Sulphate, the Phosphate 
 
 group and the Chloride group. If no precipitate obtained, the 
 Nitrate group is present. 
 
 8. If the original solution acidified with nitric acid gives a 
 precipitate with Barium Nitrate, the compound is a SULPHATE. 
 This precipitate, taken up in a soda bead, and exposed to the 
 inner flame of the blowpipe, will stain a silver coin black upon 
 the addition of a drop of water or muriatic acid, under the 
 evolution of hydrogen sulphide gas, readily recognized by its 
 odor. This is the so-called hepar test. 
 
 9. If the neutral or slightly alkaline solution of the sub- 
 stance examined yields a white precipitate with Calcium Sul- 
 phate, the PHOSPHATE GROUP of acids is present. If the 
 precipitate upon the addition of acetic acid dissolves, it is a 
 phosphate (compare p. 14:6, 5-6) ; if it does not, it is an 
 oxalate. The other acids (Silicate and Fluoride) are most 
 readily detected in the dry way (10.5; 11, 4). 
 
 10. If no precipitate yet obtained, another portion of the 
 original solution is acidified with nitric acid and a few drops of 
 silver nitrate are added; a curdy precipitate indicates the 
 CHLORIDE GROUP. The precipitate is separated and washed 
 by decantation, and treated with strong ammonium hydrate, 
 to ascertain whether the curdy precipitate is soluble or not 
 therein. In the latter case, it is an IODIDE. 
 
 11. If soluble, it is either BROMIDE or CHLORIDE (for 
 cyanide would have been detected in 5). If the original so- 
 lution with chlorine water turns yellowish, and if upon shak- 
 ing with chloroform this turns orange while the aqueous 
 solution becomes colorless, a bromide is present; if not, the 
 substance is a chloride. 
 
 12. If no precipitate so far obtained, the given compound is 
 a Nitrate, Acetate Chlorate or Borate. An excess of concen- 
 
WET WAY ANALYSIS OF ACIDS. 
 
 249 
 
 trated sulphuric acid being added: to one portion add copper 
 turnings, rutilant vapors prove the Nitrate; to another add a 
 few drops of alcohol, the odor of acetic ether indicates acetates. 
 If neither of these, add a drop of concentrated sulphuric acid 
 to a small fragment of the substance - yellow, chlorous gas 
 evolved proves the CHLORATE. 
 
 If no such odor or gas, try flame coloration ; if outer mantle 
 green, the substance is a BORATE. 
 
 If all these reactions failed to give a positive result, the 
 substance is an oxide or hydrate, to be recognized by its 
 physical characters. 
 
 56. RECOGNITION OF SPECIMENS. 
 
 1. This concludes the introduction to inorganic chemistry. 
 If this course has been complemented by laboratory work, the 
 student now is fairly familiar with the most important SUB- 
 STANCES, FACTS AND PRINCIPLES of inorganic chemistry. 
 
 2. He will have acquired the important ability of the 
 RECOGNITION OF SPECIMENS of minerals and chemical 
 compounds, mainly by their physical properties, but aided by 
 simple chemical tests made either by the blowpipe, or by a 
 drop of a dozen or two of reagents applied to the minute 
 sample in a watchglass or on a microscope slide. 
 
 3. The MICROCHEMICAL REAGENTS for this sort of 
 testing in the wet way are kept in small bottles with 
 pipette and ground glass cap, or cork stoppered, the stopper 
 carrying from below a short piece of glass rod dipping in the 
 liquid. Of course, the drop taken must be placed on clean 
 glass, near the drop or substance to be acted upon, to prevent 
 contamination of the reagent. By a working glass rod the 
 mixture- is effected. 
 
 4. The necessary SULPHURETTED HYDROGEN GAS is 
 generated in a test tube, broken below, divided into two equal 
 compartments by a perforated cork disk, and inserted into a 
 
250 
 
 LECTURE 56. 
 
 cylinder or salt mouth flask with dilute muriatic acid. The 
 tube is held at any desired depth by means of a cork wedge. 
 The upper compartment contains a couple of pieces of iron 
 sulphide, and is closed by a cork, through which passes a 
 glass tube connected with rubber tube and spring clamp. 
 To the rubber attach the delivery tube. 
 
 5. Depressing the tube starts the GENERATION OF THE 
 GAS, only a few bubbles of which are required at a time. 
 When not at work, be sure to have the cork partition a centi- 
 meter above the level of the acid. Such a little apparatus is 
 a perfect substitute of the Kipp generator for the elementary 
 microchemical work here contemplated. 
 
 6. THE TABLES given in this text (Lectures 22, 53, 54, 
 55), are sufficient for the beginner. A minute fragment of 
 the solid is all the MATERIAL REQUIRED for testing. A few 
 watch glasses and microscope slides take the place of the test 
 tubes, beakers and flasks. A few pieces of hard (Bohemian) 
 glass tubing and an alcohol lamp (glass) will permit to add 
 dry way work. The work is most interesting and instructive. 
 
 7. FOR EXAMPLE, a small prismatic crystal is given for 
 
 recognition. A portion thereof, in a watch glass, dissolves- 
 readily in a drop of water. Dots made with this solution are 
 placed on a microscope slide (or slides). With H and 
 H S^te, no Pr; these with the sulphide gas give Pr, first y, 
 then bn, finally bk; Pr with drop of water, run off, leaves 
 residue insoluble in drop of yellow Am evidently Hgi^^ 
 
 compound. Confirm by Ka lo’^^’ Cu, etc. 
 
 Excluded are acids: C^te, etc.; H^te, etc.; Cr^te, loide. 
 No effervescence, no volatile acid. Dot acidified with a touch 
 of dil. H N^te gives no Pr. with Ba Sol; P^te group excluded 
 on account of insolubility; another acidified dot with a touch 
 of Ag gives white curdy Pr — readily sol. Am Hate, hence 
 either Cf^e of Br’^e, since Cyi^e proved absent — BH^e test 
 made in watch glass with single drops shows no BF^e reaction. 
 Hence, crystal was Hgic Cfde, CORROSIVE SUBLIMATE. 
 
RECOGNITION OF SPECIMENS. 
 
 251 
 
 8. RECOGNITION OF COMMON MINERALS should be 
 practiced on small fragments, and cleavage pieces ; the greatest 
 dimension need not exceed one centimeter, so that a large 
 number of specimens can be given in a small paper tray or an 
 ordinary specimen tube. Hardness should be determined by 
 the nail, copper, glass and file. Gravity need not be actually 
 determined, if blowpipe or microchemical tests applied, or if 
 the work is restricted to the most common minerals. 
 
 9. If determinations of the specific gravity are wanted, 
 make a HYDROSTATIC BALANCE, by replacing one horn pan 
 of the common German hand scale by a double pan of wire 
 gauze held about 8 or 10 cm. apart by brass wires; the lower 
 of these pans being submerged in the water of a small crystal- 
 lizing dish. For weights, use common block weights from 10 
 gr. to 1 cgr. Weigh specimen in air on upper, in water on 
 lower wire gauze pan. 
 
 10. CLEAVAGE pieces frequently permit good determina- 
 tions by means of our goniometer,_ p. 68. Thus Barite and 
 Celestite give right rhombic cleavage pieces. For Barite the 
 angle of the prism is less than 102 degrees (11, 9); but for 
 Celestite this angle is 104 degrees, a difference easily recog- 
 nized. In fact, Hauy distinguished these mineral species by 
 this notable difference, before strontium was known, a feat 
 comparable to modern distinctions by spectrum lines. (Traite, 
 T. 2, 318-326; Paris, 1801). 
 
 11. A DIAGRAM on which the leading mineral species are 
 located according to their G and H as horrizontal and vertical 
 dimensions, (co-ordinates) is very useful for the recognition of 
 minerals. Thus, at about H 6 and G 5 are located three 
 species only, namely Pyrite, Hematite and Magnetite. But 
 the first is readily distinguished by its brilliant metallic luster 
 and yellpw color (9, 8), while the last two are distinguished 
 by their streak (9, 6) . 
 
 12. On such a diagram, the species of a genus form some 
 definite curve, showing that the PHYSICAL PROPERTIES ARE 
 
252 
 
 LECTURE 57. 
 
 DEFINITE FUNCTIONS OF THE METAL. Thus the sul- 
 phates R O4S in which R is Ca, Sr, Ba, Pb form the definite 
 curve parallel to and a little below the curve for the corres- 
 ponding carbonates R O3C, which are about half a degree 
 harder. The author has found work of this character far 
 superior to the common study of systematic chemistry. 
 
 57. ORGANIC PRIME MATERIALS. 
 
 1 . Minerals constitute the body of the earth. Together 
 with the water of the ocean and the gases of the atmosphere, 
 they have furnished the prime materials for our chemical in- 
 vestigations. Thus far, we have studied inorganic chemistry 
 only. 
 
 2. Under the action of the light and heat of the sun upon 
 the air and moisture, the surface of the earth has been covered 
 with plants. Attached to the mineral world by their roots 
 ramifying in the soil, they push stem and branches up into the 
 air and unfold their leaves to the sunbeam which every season 
 calls forth flowers and fruits as the highest forms of VEGETA- 
 BLE MATTER. 
 
 3. Almost every portion of vegetable matter is utilized by 
 animals as food. To secure this, animals are endowed with a 
 power of voluntary motion. Vegetable matter is transformed 
 by the animal into bone, muscle and nerve; also into egg, 
 blood and milk. Such substances are ANIMAL MATTER. 
 
 4. The whole earth becomes more and more the GARDEN 
 OF MAN. “Out of the ground grow trees pleasant to the 
 sight and good for food.” Man is getting a more complete 
 “dominion over the fish of the sea, over the fowl of the air, 
 and over every living thing that moveth upon the earth.” 
 But the earth “brings forth thorns also and thistles,” so that 
 “man eats his bread in the sweat of his face.” Genesis, 1-3. 
 
ORGANIC PRIME MATERIALS. 
 
 5. Plants and animals furnish the prime materials for or- 
 ganic chemistry, as minerals do for inorganic chemistry. 
 ORGANIC CHEMISTRY, in its broadest sense, treats of the 
 changes of matter of the organic world. — 1. 5-7. 
 
 G. The starchy grain, when germinating, becomes soft, 
 sweetish, gummy; a new plant grows from it. In the leaves 
 of this new plant we notice green coloring matter, woody cell 
 tissue, acids; at least during flowering, volatile substances are 
 formed; then new grains make their appearance, at first gum.- 
 my, then sweetish, finally starchy. Such a cycle of changes 
 is a subject for investigation in organic chemistry; its 
 LABORATORY IS THE CELL, its power, the Sun. 
 
 7. This new grain, mixed with malted barley, changes to 
 a sugar ; exposed to the ferments of the air, it produces alcohol ; 
 this is readily converted into thousands of new materials, 
 such as acetic acid, aldehyd, chloral, chloroform and ethers. 
 Many such processes have for centuries been practiced on a 
 large scale; they are OPERATIONS OF ORGANIC CHEMIS- 
 TRY. 
 
 8. Organic matter contains carbon, as is readily shown by 
 the simple test of charring (1, 5), which also generally per- 
 mits us to distinguish animal from vegetable matter. Accord- 
 ingly, modern chemists have defined organic chemistry as the 
 chemistry of carbon compounds, ostensibly to maintain the 
 unity of the science of chemistry; but the innovation is 
 rather narrow. 
 
 9. As a matter of fact, the products of the soil throughout 
 the world and their modifications by animals furnish almost 
 exclusively the PRIME MATERIALS OF ORGANIC CHEMISTRY. 
 In the economy of nations, these products alone are of import- 
 ance. To increase their production, to improve their quality, 
 and multiply their forms of application, marks the main work- 
 ing field of organic chemistry. In this field the United States 
 are prominent. 
 
254 
 
 LECTURE 58. 
 
 10. In the course of the chemical changes of these prime 
 materials, many NEW and valuable PRODUCTS are obtained, 
 first in the laboratory and afterwards in the factory. But in 
 nearly all cases, these new substances either are identic with 
 or correspond to substances furnished by plant or animal, and 
 often were already used by the ancients. 
 
 11. This is especially striking regarding the COAL-TAR 
 PRODUCTS, the investigation of which has, in some regions, 
 almost monopolized the efforts of the chemist. This inevita- 
 ble one-sidedness has led to systematic errors, and boastful 
 assertions of superiority as unfounded as they are unbecoming. 
 
 12. Hasty conclusions, unwarranted generalizations and 
 bulky publications have marred the work of the last quarter 
 century. THE CHEMICAL PRESS has become rather sensa- 
 tional, not merely in its diagrams and long names. In real 
 science, we need more earnest thought, less haste; more 
 grain, less straw in our publications. In our industry and 
 intercourse, less of the modern “survival of the fittest,” a 
 heartless philosophy of doubtful foundation ; more of a revival 
 of the moral code and the golden rule. 
 
 58. SUGAR AND WINE. 
 
 1. The tall SUGAR CANE has its home in Asia (India and 
 China). The Arabs planted it in Italy and Spain. Since it 
 has found its most extended cultivation in America, from Cuba 
 to Brazil. The juice (90 per cent.) of the ripe cane is sweet; 
 it is a strong sulution (10 to 18 per cent.) of true sugar, the 
 SUCROSE of modern chemistry. 
 
 2. The juice is pressed out by passing the cane between 
 revolving cylinders. Gentle heating with a little lime removes 
 impurities. Concentration in (open and vacuum) pans gives 
 crude sugar in crystals, and molasses. In the refineries of 
 Europe and the United States (14, 11), the pure, crystallized 
 
SUGAR AND WINE. 
 
 255 
 
 sugar is obtained. Tropical America produces one and one- 
 half million tons.^ Asia, Africa and Australia one million tons. 
 Total, two and one-half million tons of cane sugar a year. 
 
 3. SUGAR (sucrose) is a white solid without odor. G 1.6; 
 F 160, solidifying to a white, amorphous, vitreous mass, grad- 
 ually becoming opaque and again crystalline. At higher tem- 
 peratures it chars and burns. 
 
 Sugar is soluble in half its own weight of cold water, and in 
 all proportions in hot water. From its solution it crystallizes 
 in oblique rhombic prisms (M M' 101.5 and M P 98.5) called 
 Rock candy. The Maple sugar of New England is also 
 mainly sucrose. 
 
 4. The same sugar (sucrose) was discovered by Marggraf 
 of Berlin in the juice of the beet (1747). About 1830 France 
 had 50 beet sugar factories; twenty years later the beet sugar 
 production had taken root in Germany and Austria. These 
 two countries now produce two million tons of BEET SUGAR, 
 while the balance of Europe produces one and one-half million 
 tons only. Total, three and one-half million tons of beet 
 sugar a year (1889-90). 
 
 5. Honey and Manna were the only SWEET SUBSTANCES 
 known in antiquity, even to the Greeks. The Hindoos had 
 extracted sucrose from the cane, 500 B. C. The Arabs 
 brought sucrose to Southern Europe. With the importation of 
 slaves, cane planting began in tropical America. During the 
 last forty years, chemistry has profoundly modified agriculture 
 in Central Europe, which now extracts more sucrose from the 
 beet root than is produced in the sugar cane of the tropics. 
 
 6. States, recognizing the economic advantages of increas- 
 ing and diversifying the industries, have at all times fostered 
 new industries by SPECIAL LEGISLATION. The history of 
 the beet sugar industry shows the marvellously stimulating 
 effect of such legislation, but also the depression that seems 
 an unavoidable sequence. Europe now is in the latter stage. 
 
256 
 
 LECTURE 58. 
 
 while we are entering upon the first stage by voting a bonus 
 upon the production of all sugar. 
 
 7. Ripe GRAPES taste sweet; but no sucrose can be 
 extracted from them. When dried (raisins), the sweet prin- 
 ciple appears as a gritty solid, called grape sugar or GLUCOSE. 
 It promptly reduces the boiling Fehling-Solution (an alkaline 
 tartrate of copper) giving a red precipitate of cuprous oxide. 
 Afresh sucrose solution gives no precipitate; hence the im- 
 portance of this test. Figs and many other fruits give the 
 same reaction; so does honey; they contain glucose. 
 
 8. When ripe grapes are piled up, they burst under their 
 own weight; the rich, sweet juice or must (95 per cent, of 
 berry) runs out. Set aside in filled vessels, it undergoes a 
 remarkable change, called FERMENTATION, during which 
 much fixed air (16.8) is given off. Finally, the liquid becomes 
 clear again: it is WINE, the special product of the white race, 
 the milk of old age that ought to be but sparingly used by the 
 young. 
 
 9. WINE MAKING is probably the oldest chemical industry. 
 The patriarchs made wine and drank it. The Egyptian 
 monuments show the cutting of the grapes from the trellises, 
 and the pressing of the must. The Greeks and Romans held 
 wine in high esteem. Among modern nations, the French 
 produce the most, over 2,000 million gallons a year before the 
 phylloxera came, and about 800 million gallons a year during 
 the last 10 years. Spain, Italy and Germany come next. 
 In America, California has long been foremost, both in amount 
 (12 million gallons) and quality of the wine produced. 
 
 10. Slow distillation of wine yields a very volatile liquid, 
 known in the 13th century as AQUA VIT/E and used as a 
 medicine, to which the most extravagant virtues were ascribed. 
 This is our brandy. The finest is produced in France (Cognac) . 
 California also manufactures good brandy in large quantities. 
 Its specific gravity should range between 0.92 and 0.9T. It is 
 readily inflammable, burning with a pale blue flame, leaving a 
 liquid residue. 
 
SUGAR AND WINE. 
 
 257 
 
 11. Subjecting brandy to fractional distillation, the most 
 volatile fractions become lighter and more completely com- 
 bustible (spirits). When the specific gravity is reduced to 
 about 0.82, the liquid is properly called ALCOHOL. By care- 
 ful distillation it can be brought down to 0.81 When distilled 
 from quick lime (after a day*s contact therewith in a closed 
 vessel), the distillate may be brought down to 0.79, boiling at 
 78.°4. This is ABSOLUTE ALCOHOL, solidifying at - 130 de- 
 grees. It is extremely hygroscopic. 
 
 12. The alcohol of 0.82 contains 94 per cent, of absolute 
 alcohol by volume, 91 per cent, by weight; the STRENGTH 
 OF AN ALCOHOL, containing only water as diluent, is de- 
 termined by its specific gravity, 47, 11. 
 
 Alcohol is PRODUCED (for industrial purposes) in enormous 
 quantities from various sources in these days. In the year 
 1890-91, Germany produced 75 million gallons, France 50, 
 Russia 100, Austro -Hungary 50, England 25; total 300 million 
 gallons (of 100 per cent.) or a million gallons a day. The 
 production of the United States is also very great. 
 
 59. FATS AND OILS. 
 
 1. The basin of the Mediterranean Sea, the seat of civili- 
 zation of antiquity, is the home of the olive tree. The Greeks 
 regarded it as a symbol of peace, a gift of the Gods. Its wood 
 is hard, growth slow, size moderate, foliage elegant, flowers 
 delicate, white and fragrant, fruit fleshy, containing half its 
 own weight of the purest fatty oil, yielding to simple pressure: 
 OLIVE OIL. It is yellowish, G 0.915, and begins to solidify 
 at 5^ 
 
 2. The portion of olive oil remaining liquid at the freezing 
 point is called OLEIN ; it amounts to about three -fourths of 
 the oil. The last traces of the solid constituent of olive oil are 
 removed by repeating the process. 
 
258 
 
 LECTURE 59. 
 
 Olein remains liquid on exposure to the air; it is a non- 
 drying oil. It congeals at — 6 degrees, is soluble in ether and 
 in boiling alcohol. Rutilant vapors solidify it; this solid 
 (elaidin) melts at 32 degrees. 
 
 3. The solid residues of sweet oil are, by pressure, freed 
 from the olein adherent, the last traces of which are extracted 
 by boiling alcohol; what remains is called PALMITIN or 
 margarin. Crystallized from ether, it melts at 61 degrees, 
 but may be cooled to 41 degrees before it solidifies again. 
 Accordingly, sweet oil is a mixture of about three parts of olein 
 and one of margarin. These two fats are also the constitu- 
 ents of the fat of the human body. 
 
 4. The hunter and herdsman obtained the fat required for 
 food from the animals he captured or raised. The best, most 
 readily digested fat, is BUTTER; it is also the most complex, 
 so that its consideration must be deferred for the present. By 
 melting on a water bath, animal fats are obtained in the purest 
 form; especially TALLOW, melting at 45-46 degrees, from the 
 ox; LARD, (38-40 degrees) from the hog, and SUET (50 de- 
 grees) from the sheep. Goose grease melts at 25-26 degrees; 
 it does not deserve the neglect it receives in modern medicine, 
 which prefers inert, non-assimilable petroleum products. 
 
 5. When cold lard is subjected to hydraulic pressure, LARD 
 OIL runs out and a white solid, STEARIN, remains. 
 
 Lard oil is produced in enormous quantities in America; it 
 has the general properties of olein, but betrays its hog-origin by 
 instantly producing reddish-brown color in contact with con- 
 centrated sulphuric acid. This coloration is evidently due not 
 to the main body of the lard oil, but to an ingredient present 
 in small amounts only. 
 
 6. The solid fat STEARIN is obtained pure by pressing 
 purified suet at 25 degrees, dissolving the residue in its own 
 volume of hot ether, from which stearin crystallizes on cool- 
 ing. These crystals are purified by pressing, and recrystalli- 
 zation. 
 
FATS AND OILS. 
 
 259 
 
 Stearin melts at 70 degrees; it is but little soluble in alco- 
 hol and ether at common temperatures; it freely dissolves in 
 boiling ether. Suet contains one-fifth olein; the balance is 
 margarin and stearin. 
 
 7. FATS FROM FISH are generally recognized by their 
 odor. A single whale (physeter) will furnish 80 tons of whale 
 oil, mainly consisting of two liquid fats, olein and physetolein. 
 Cod Liver Oil is extracted from the liver of Gadus Morrhua 
 and kindred species of gadus. It consists mainly of olein; 
 owes its reputation to ingredients present in minute quantities, 
 and not yet fully known. A drop of concentrated sulphuric 
 acid produces a series of colors resembling the strychnine 
 color reaction. See 64, 11. 
 
 8. Linseed yield upon pressure a fixed oil which, on ex- 
 posure to the air, dries to a varnish. It contains about 20 per 
 cent, of solid fats; no olein, but the liquid, drying linolein 
 instead. Accordingly, it does not solidify with rutilant vapors. 
 By boiling with litharge, the drying qualities of the oil are im- 
 proved. 
 
 9. In general, fatty substances are greasy to the touch, 
 and non-volatile, leaving on paper a permanently transpar- 
 ent spot. They are lighter than water (on which they float) ; 
 G 0.90 to 0.94. At common temperatures they are either 
 solid (fats) or liquid (OILS). They may be separated by 
 cold and pressure into a few simple fats of perfectly definite 
 properties (stearin, margarin, olein). They are insoluble in 
 water, partly soluble in (hot) alcohol, readily soluble in ether. 
 They are combustible; when incompletely burnt they emit a 
 characteristic odor (acrolein). When kept exposed for a long 
 time, they become rancid (odor). 
 
 10. Before the war, cotton seed was a waste product in our 
 southern states. Now, the COTTON SEED OIL adds mate- 
 rially to the profit of the planter. Enormous quantities are 
 produced; much goes to the packing establishments of this 
 country, and “over six million gallons are shipped annually to 
 
260 
 
 LECTURE 60. 
 
 Mediterranean ports contiguous to the olive oil industry” 
 (Remington). Alcoholic silver nitrate solution, shaken with 
 cotton seed oil, and heated, tinges the oil red or reddish- 
 brown. 
 
 11. The fact is, lard oil, cotton seed oil and olive oil 
 consist mainly of olein and margarin in similar proportions. 
 By density and solidification they can not be distinguished. 
 It is true, lard oil produces a COLOR REACTION with sul- 
 phuric acid and cotton seed oil another with silver nitrate 
 solution; but these tests indicate the presence of an impurity 
 that may be removed. Of course, good cotton seed oil is a 
 good oil, and will bring a good price sold under its own name. 
 
 12. To conclude the identity of these oils is manifestly 
 absurd. The constituents present in minute amount, the 
 combinations breaking down before our reagents, often are the 
 most valued, to say nothing of the history or provenance of 
 the material. The “artificial wine” may yield the same 
 analytical results as a true wine; yet the maker of the first is 
 condemned in Germany, where the latter brings’ a high price. 
 Frauds in oils and fats are frauds; where chemistry fails to 
 detect it, the brand of an honorable firm will protect the con- 
 sumer and the producer. 
 
 60. FLOWER AND FRAGRANCE. 
 
 1. Its highest form of beauty and fragrance, the vegetable 
 world has produced in THE ROSE. Though in the lower sense 
 “useless” — offering nothing for the stomach — the rose has 
 ever been held in the highest estimation by man. Flundreds 
 of varieties have been produced by culture; but the old centi- 
 folia and damascena are among the richest in fragrance. 
 
 2. In the Orient, the culture of the rose has remained 
 economically prominent in numerous localities. The country 
 about Kisanlik, in Bulgaria, largely supplies the market with 
 the OIL OF ROSE, in which the subtle fragrance is concen- 
 trated in a permanent form. This oil, quoted at about a dollar 
 
FLOWER AND FRAGRANCE. 
 
 2G1 
 
 a drachm, represents fully three thousand times its own weight 
 of the delicate rose petals. It is a pale, yellowish, transparent 
 liquid (G about 0.87 at 20 degrees), congealing between 16 
 and 21 degrees to a transparent solid with many slender, 
 shining crystals. 
 
 3. The oil of rose is obtained by distilling rose petals with 
 water; the oil floats on top of the distillate. VOLATILE OILS, 
 even if of much higher boiling point than water, are readily 
 carried over with the large excess of water vapor in this pro- 
 cess of distillation, which is quite generally employed for the 
 extraction of the fragrant principles of plants. In some dis- 
 tricts this ATTAR is distilled without the addition of water to 
 the petals, the latter containing a sufficiency for the purpose. 
 
 4. Many of the most beautiful and FRAGRANT FLOWERS 
 are grown on a commercial scale in favored regions in the 
 open, and throughout the civilized world under glass, to supply 
 the demand in the immediate vicinity for the flower. Flori- 
 culture has enormously increased during the last quarter 
 century. Florists have also learned to ship their perishable 
 products long distances, as from Sicily to England. 
 
 The southeastern corner of France, with Nice as the com- 
 mercial center, is the most remarkable flower garden of 
 modern times. The country, gently sloping towards the 
 sunny Mediterranean, is completely protected by the Maritime 
 Alps against the chilling winds of the north. From this 
 favored region, fresh flowers are shipped to the north — as far 
 as England — during the winter, and the fragrance of flowers 
 is extracted on a large scale throughout the year. 
 
 5. The finest and most delicate fragrance of flowers suffers 
 to an appreciable extent by the process of distillation with 
 water. For such flowers, the process of ENFLEURAGE has 
 been devised, in which the purest fats (lard), spread in thin 
 layers on glass frames, absorb the fragrance of the flowers at 
 common temperatures. The flowers are laid or sprinkled on 
 these “chassis,” of which a number are piled to a stack. In 
 from 6 to 12 hours the fats have absorbed all the fragrance ; 
 
262 
 
 LECTURE 60. 
 
 the exhausted flowers are removed and replaced by fresh ones 
 till the fat is saturated. 
 
 6. This POMADE is the commercially permanent form in 
 which the concentrated fragrance of the flower is shipped 
 throughout the world. The largest establishments of this 
 manufacture are at Grasse, about 15 miles west of Nice. This 
 industry is strongly marked by peculiar characters for which 
 French industry is noted. In a very small bulk, an immense 
 amount of skilled labor and scientific thought has been con- 
 densed ; a very small weight brings the producer a very large 
 sum of money. 
 
 7. - The receiver — retailer — of these pomades, cuts them 
 into small pieces, and shakes these with the proper amount 
 of purest alcohol, which dissolves the fragrance, forming the 
 so-called ESSENCE of the flower; the fat being insoluble in 
 alcohol, is removed by decantation (best after standing in the 
 cold) . It is only when properly diluted that the real fragrance 
 is brought out. 
 
 8. Algiers, Australia and the United States have made a 
 good start in this interesting and profitable field. The pepper- 
 mint culture and industry of Michigan has attained a control- 
 ling influence in the market. The OIL OF PEPPERMINT is 
 distilled with water from the leaves and tops of Mentha 
 piperita, gathered before flowering. The oil (G 0.91) has 
 “the characteristic odor of peppermint; a strongly aromatic, 
 pungent taste, followed by a sensation of cold when air is 
 drawn into the mouth.” 
 
 9. The small evergreen shrub, rising at intervals from the 
 creeping root of Gaultheria procumbens yields, upon the 
 distillation of its oval, leathery leaves, the OIL OF WINTER- 
 GREEN, the heaviest of all volatile oils (G 1.18, B 218-221). 
 It is colorless or yellowish, and has a strong specific odor, a 
 warm aromatic taste ; it is soluble in alcohol; when shaken 
 with water, a deep violet color will be produced upon the 
 addition of a drop of ferric chloride. 
 
FLOWER AND FRAGRANCE. 
 
 2G3 
 
 10. An “artificial” or “synthetic” oil of wintergreen 
 has been put on the market; being made from “synthetic” 
 salicylic acid, obtained from coal tar, it is profitably supplied 
 at half the price of the genuine. 
 
 The “artificial” is in no sense chemically identical with the 
 genuine; it is not even a safe “substitution.” But it is de- 
 clared to be as good as the genuine, and that it has driven the 
 genuine out of the market, so that even “salicylic acid made 
 from oil of wintergreen” is no longer genuine. “If cheaper 
 and better,” it ought by all means to be sold under its own 
 name. Such a condition is deplorable, demoralizing. It can 
 be met by a reliable “brand” only. See 59.12. 
 
 11. Several volatile oils are obtained BY EXPRESSION, 
 notably the oils of bergamot, of orange peel and of lemon peel. 
 For further details, special treatises must be consulted about 
 this entire subject. 
 
 The pure volatile oils make a STAIN on paper; but this 
 stain completely disappears on exposure, while the stain made 
 by fatty oils is permanent. 
 
 12. From peppermint oil separates a crystallized solid*, called 
 MENTHOL (G — , F 43, B 212), volatilizing considerably at 
 common temperatures. The Japanese oil is particularly rich 
 in menthol, which first reached us from Japan. 
 
 Camphor (G 0.995, F 175, B 204), distilled with water 
 from the wood of the camphor tree of Formosa, is similar to 
 menthol, but has been long in use. Its odor is characteristic 
 and well known. 
 
 61. INDIGO AND MADDER. 
 
 1. The vegetable world presents in its flowers all the 
 colors of the rainbow; it also shows rich color in fruit and foli- 
 age, and even in wood and root. Man has tried to extract and 
 employ these colors; but the tints of the petals have almost 
 invariably proved too dainty for his hands. From the other 
 
264 
 
 LECTURE 61. 
 
 parts of the plant, SUBSTANTIAL COLORING MATTERS have 
 been obtained. 
 
 2. Already in antiquity, these colors were transferred to the 
 vegetable fibre by which man protected and adorned his body. 
 The oldest part of the Scriptures speak of GARMENTS DYED 
 in red, purple and scarlet. The heros of Homer wore purple. 
 The dyers of Tyre and Sydon were famous. The Egyptians, 
 as Pliny reports, understood the use of mordants, apparently as 
 well as we do to-day. 
 
 3. INDIGO is one of the oldest vegetable colors; it has 
 been in use at least three thousand years, and is as important 
 to-day, as ever. Eight thousand tons of indigo, worth over 
 twenty million dollars, are produced annually, mainly, in India, 
 its home, whence Alexander brought it to Greece as indian 
 (indicon) blue. In naming the substance we state its origin. 
 
 4. The plant, indigofera tinctoria, shows no blue coloring 
 material. Shortly before flowering, the plant is cut off, thrown 
 into great vats with water and lime; a sort of fermentation 
 sets in, the coloring material passing into solution. This 
 greenish -yellow solution is drawn into lower vats, beaten with 
 bamiboos for hours to introduce air; now a blueish sediment 
 settles to the bottom — it is the CRUDE INDIGO, about one 
 fifth of one per cent of the plant taken. 
 
 5. The crude indigo of commerce contains several coloring 
 principles. Its percentage of true indigo is extremely variable, 
 ranging from 20 to 90. The deep blue lumps show a reddish 
 streak. PURE INDIGO is obtained by mixing the pulverized 
 crude substance with its weight of pulverized glucose, dissolv- 
 ing in alkaline alcohol. The yellowish solution is decanted; 
 upon exposure to the air indigo gradually precipitates, and 
 after washing with dilute muriatic acid, is pure. 
 
 6. PURE INDIGO BLUE is a blue, tasteless (crystalline) 
 solid, insoluble in water, alcohol, ether, acids and alkalies, 
 slightly soluble in chloroform, glacial acetic acid and spirits of 
 turpentine, from which solutions it separates in acicular crys- 
 
INDIGO AND MADDER. 
 
 2G5 
 
 tals. When carefully heated, it forms a sublimate of red 
 acicular crystals; its vapors are purplish red. It is soluble in 
 fuming sulphuric (Nordhausen) acid. In reducing alkaline 
 liquids it dissolves to a colorless liquid, indigo-white (Chevreul, 
 p. 37); on exposure to the air it returns to indigo-blue or 
 true indigo. This explains the common method of dyeing 
 with indigo. 
 
 7. India is also the home of rubia tinctorum (MADDER), 
 the root of which has served from time immemorial as the 
 principal red dye. From the Orient, the culture of madder 
 reached Europe in the 17th century, and became specially 
 prominent in southern France. Since 1869, this old industry 
 has almost disappeared, not only from France, but also from 
 Asia Minor and other countries, to the great loss of the popu- 
 lations affected. 
 
 8. The pulverized madder, treated with its own weight of 
 sulphuric acid, gives a blood red mass, the garancine of the 
 French. Exhausting this with boiling alcohol, the cooling 
 liquid deposits yellowish brown acicular crystals of ALIZARINE 
 and purpurine. Both are soluble in a boiling solution of alum, 
 from which alizarine precipitates on cooling. This is the color- 
 ing principle of madder. 
 
 9. The reddish yellow crystals of PURE ALIZARINE melt at 
 215°, volatilize between this temperature and 240°; they can 
 be sublimated in a porcelain crucible heated on a sandbath. 
 Alizarine is scarcely soluble in water, moderately soluble in 
 boiling water and in alcohol. It dissolves in sulphuric acid, 
 which it colors blood red. Its alcoholic solution is turned violet 
 by alkalies; lime turns it blue. A hot alum solution dis- 
 solves it; on cooling, it precipitates in crystal form. 
 
 10. In 1869 the German Chemists, Graebe and Lieber- 
 mann, succeeded in producing alizarine from anthracene, one 
 of the least volatile constituents of coal tar. Their method 
 was unpracticable, however. The English Chemists, Caro 
 and Perkin, soon after, devised a chemical method both simple 
 
26G 
 
 LECTURE 62. 
 
 profitable. Since then, ALIZARINE IS MADE on a large scale 
 FROM COAL TAR, and the madder culture has been ruined. 
 France used to export six million dollars worth of madder; now 
 Germany produces that much alizarine from coal tar. 
 
 11. The two vegetable colors presented are TYPICAL of 
 this important class of bodies. Many lessons, economic as 
 well as scientific, can be drawn from what has been stated. 
 
 In conclusion, the economic value of colors extracted from 
 woods (logwood, etc.), may be estimated from the fact that 
 Europe, in 1888, imported two hundred thousand tons of such 
 woods from the tropics, representing about eight million dollars 
 in value. 
 
 12. The most important vegetable color of all has not been 
 mentioned yet; it is CHLOROPHYLL, the green color of 
 leaves. It is insoluble in water, but soluble in alcohol, and 
 especially in ether. By frost it is decomposed into red and 
 yellowish tints, so admirably exhibited by American forests in 
 the fall season. In spring, more delicate tints mark the swell- 
 ing and opening buds— but require more attention to be seen. 
 
 62. BALSAM AND RESIN. 
 
 1. We read of “wise men from the East” having been 
 miraculously guided by a star to the new-born King; “and 
 when they had opened their treasures, they presented to him 
 gifts: gold, and frankincense, and myrrh.” This is a formal 
 recognition of the estimation in which Orientals hold choice 
 resins and balsams — treasured with gold. 
 
 2. Modern man looks down upon such customs as manifes- 
 tations of ignorance and superstition— and then dives into the 
 TAR PIT, applies all his powers and extracts by highest 
 chemical art “new” substances of wonderful properties, makes 
 the use of these products almost compulsory to cure and pre- 
 vent disease, and to preserve food from corruption ’till needed 
 for strength. 
 
BALSAM AND RESIN. 
 
 2G7 
 
 3. And lo! these vaunted NEW SUBSTANCES owe their 
 value exclusively to their correspondence with the exudations 
 of the fragrant shrubs and trees of India, Arabia and Africa, 
 used and prized from time immemorial by our superstitious 
 ancestors who, however, were not ignorant enough, by such 
 substances, to make their food indigestible. The Egyptians 
 preserved their lifeless bodies, but they did not embalm their 
 food. 
 
 4. BENZOIN is a balsamic resin, obtained from Styrax Ben- 
 zoin, a tree at home on Sumatra and Java. Alcohol dissolves 
 most of its active principles. When moderately heated, it 
 yields a crystallized aromatic sublimate, insoluble in water, 
 but soluble in sodium carbonate with effervescence, and re- 
 precipitated by sulphuric acid. The sublimate, accordingly, is 
 a true acid; it is called benzoic acid. 
 
 5. Scheele (p. 169) made use of the wet way reactions just 
 stated to extract pure benzoic acid from benzoin. 
 
 When the acid is heated in a distilling apparatus with three 
 times its weight of slacked lime, a colorless distillate is ob- 
 tained, called BENZOL (Mitscherlich, p. 34). This sub- 
 stance is the starting point of all aromatic compounds. We 
 give the characteristic of these two bodies. 
 
 6. BENZOL is a colorless, very limpid liquid of a character- 
 istic odor. G 0.90 at 0, F 0°, B 80.4; crystallizes in rhom- 
 bic octahedr^. Insoluble in water, soluble in alcohol and 
 ether. Is a good solvent for iodine, sulphur, phosphorus, 
 camphor, wax, fats, and india rubber. It burns with a 
 fuliginous flame. 
 
 7. BENZOIC ACID (Equivalent 122) is a white solid, 
 forming pearly scales or silky needles; has a slight aromatic 
 odor of benzoin, and a warm, acid taste; acid reaction. F 121, 
 B 250. , Very slightly soluble in cold water ( rJir) moderately 
 soluble in boiling water (t\), quite soluble in alcohol, ether, 
 chloroform, benzol. Freely soluble in aqueous solutions of 
 alkalies, forming soluble salts. 
 
268 
 
 LECTURE 62. 
 
 It begins to sublimate at 100° already, and freely passes over 
 with vapor of water. Neutralized solutions give a flesh 
 colored precipitate with ferric chloride. 
 
 8. We have no balsam trees in the North, but possess im- 
 mense pine forests which impregnate the air with their 
 peculiar aroma — both healthful and pleasant. The wood is 
 rich in an oleoresin (TURPENTINE), to obtain which the 
 great pine forests of our Southern States are now being 
 devastated by “turpentine orchards.” The turpentine industry 
 is old in the Carolinas. Southwestern France also produces 
 turpentine, but not in that ruthless manner. 
 
 9. When turpentine is distilled with water, OIL OF 
 TURPENTINE forms a layer on the water passing over. The 
 volatile oil may be rectified from lime water. 
 
 Oil of turpentine is a thin, limpid, very volatile, colorless 
 liquid, of a characteristic odor and taste, neutral reaction (be- 
 coming faintly acid by exposure to the air). G. 0.86 to 0.87. 
 Insoluble in water, soluble in thrice its volume of alcohol. It 
 acts on bromine or iodine with explosive violence; in contact 
 with a mixture of nitric and sulphuric acid, it inflames. Its 
 vapors mixed with air explode on ignition. 
 
 10. The residue left of the turpentine after distilling is 
 called colophony. It is a true resin, being readily soluble in 
 alcohol, and entirely insoluble in water. 
 
 COLOPHONY is a transparent, amber colored solid, hard, 
 brittle, with conchoidal fracture, showing the typical resinous 
 luster; it has a faint terebinthine odor, and is inflammable. 
 G 1.07 to 1.08, F 135. Solubility as stated above; also 
 readily soluble in ether, fixed and volatile oils. 
 
 11. Oil of turpentine, when distilled in vacuo or in an 
 atmosphere of fixed air, is destitute of odor. Exposure to the 
 air reproduces the odor, which accordingly is due to the oxida- 
 tion of the oil, which thereby is resinified. All volatile oils 
 seem to possess this peculiarity. In the same manner, pure 
 arsenic distilled in fixed air has no odor; it exhibits the 
 characteristic garlic ODOR ONLY WHILE BEING OXIDIZED. 
 
BALSAM AND RESIN. 
 
 269 
 
 12. Turpentine yields about one fifth of its own weight of 
 volatile oil, leaving four fifths of resin. Such bodies are 
 named OLEO-RESINS. GUM RESINS consist of a gum (soluble 
 in water, insoluble in alcohol) and a resin. Myrrh and asa- 
 foetida are examples. Balsams are resinous substances con- 
 taining benzoic acid or similar aromatic volatile solids. Styrax, 
 balsam of Tolu, balsam of Peru, may be mentioned in addi- 
 tion to benzoin described. 
 
 63. VEGETABLE ACIDS. 
 
 1. Goethe voiced the longing of the children of the North 
 for the “ Sunny South,” the land where the lemon trees are 
 in bloom, and where through the dark foliage the golden 
 ORANGES glow. Nevertheless, the Northern APPLE orchard 
 in full blossom at the coming of the summer season, and 
 loaded with luscious fruit at its close, we deem the more 
 beautiful of the two. It was an apple, not an orange, that 
 tempted the mother of us all. 
 
 2. Chemically, both the lemon and the apple furnish us 
 typical ORGANIC ACIDS, namely citric and malic acids. 
 SCHEELE, that marvellously skillful chemical worker, has 
 taught us how to extract these acids. Though a century has 
 elapsed, we cannot do better than follow his directions (p. 169). 
 
 3. While climatic conditions limit the habitat of the trees 
 producing these REFRESHING FRUITS, the almost ripe fruit is 
 sufficiently resistant to stand shipment to distant countries. 
 Thus Italy and California supply the world with lemons and 
 oranges, while our Northern States send apples to Europe by 
 the million barrels. 
 
 4. THE JUICE OF THE LIME contains more citric acid than 
 the lemon and largely supplies the growing demand for this 
 acid. After freeing the juice from mucilage by a beginning 
 fermentation, it is saturated with chalk, the precipitated 
 
270 
 
 LECTURE 63. 
 
 calcium citrate washed with boiling water and treated with 
 dilute sulphuric acid. The resulting citric acid solution is 
 drawn off from the precipitated gypsum and concentrated to 
 crystallization. 
 
 5. CITRIC ACID occurs in colorless, translucent, right- 
 rhombic prisms, not deliquescent in dry air; odorless, agreeable 
 acid taste. Freely soluble in water, less so in alcohol. It gives 
 no precipitate with lime water except on boiling; the precipitate 
 redissolves on cooling (if an excess of lime water was used). 
 
 The crystallized acid (equivalent 70) begins to lose water 
 (of crystallization) at about 75; melts above 135, and decom- 
 poses at a red heat, without emitting the odor of burnt sugar. 
 
 6. The acid which Scheele in 1785 extracted from the apple 
 (pyrus malus) he called MALIC ACID. He found the same 
 acid in cherries, currants, blackberries, strawberries and 
 other fruit. The barberries, the berries of sumac (rhus glabra) 
 and of the european mountain ash are especially rich in this 
 acid. It also occurs in rhubarb and tobacco. 
 
 7. These berries of the mountain ash are gathered before 
 they are fully ripe. The juice is expressed, and clarified by being 
 brought to a boiling (albumin). The filtered liquid is boiled 
 with milk of lime, giving a deposit of neutral calcium malate. 
 After washing, this deposit is added, in small portions at a 
 time, to boiling dilute nitric acid; the acid malate so formed 
 crystallizes on cooling. These crystals are treated with lead 
 acetate, the lead malate precipitated is suspended in water 
 and treated with hydrogen sulphide gas. The filtrate yields, 
 on careful evaporation, deliquescent crystals of malic acid. 
 
 8. Malic acid (equivalent 67) occurs in acicular crystals, 
 forming mamellary groups; it is deliquescent, very soluble in 
 water and in alcohol. F 100. It begins to decompose at 
 120 degrees. 
 
 Malic acid gives no precipitate with lime water, neither hot 
 nor cold. Calcium chloride gives no precipitate, except upon 
 boiling. This precipitate, dissolved in the least amount of 
 hydrochloric acid, is reprecipitated by alcohol. 
 
VEGETABLE ACIDS. 
 
 271 
 
 9. Scheele separated several other organic acids by his 
 methods, namely: the formation of the calcium salt from which 
 the organic acid is set free by dilute sulphuric acid under the 
 separation of insoluble gypsum, or the formation of the lead 
 salt, from which the lead is separated by hydrogen sulphide. 
 In addition to the preceding acids, he extracted especially 
 oxalic and tartaric acids in this way. 
 
 10. OXALIC ACID is extracted from various species of sorrel 
 (oxalis), generally containing the potassium salt. The acid 
 is now made in quantity from starch or from sawdust. 
 
 Crystallized oxalic acid (equivalent 63) is quite permanent 
 in air (24.10) and moderately soluble in water. Calcium 
 compounds give a crystalline precipitate, insoluble in acetic or 
 oxalic acid, but soluble in muriatic acid. See p. 146, 5, a ; 55,9. 
 
 11. Potassium tartrate is contained in the ripe grape, and 
 insoluble in alcohol ; it therefore separates as tartar (argol) 
 during fermentation. This is dissolved in dilute muriatic 
 acid, and saturated with chalk. The precipitated neutral 
 calcium tartrate is washed and treated with dilute sulphuric 
 acid; the filtrate is carefully evaporated (best in vacuum pan) 
 to crystallization. 
 
 12. TARTARIC ACID (equivalent 75) forms colorless, odor- 
 less, monoclinic crystals, permanent in air. F 135, decompose at 
 higher temperature, emitting the odor of burnt sugar. Soluble 
 in water, less so in alcohol. 
 
 The acid gives a crystalline precipitate (cream of tartar) 
 with potassium acetate, insoluble in acetic acid, readily soluble 
 in alkalies and in mineral acids. 
 
 64. VEGETABLE BASES. 
 
 1. The strange potency of many plants had become familiar 
 to man long before historic times. The myths of Hekate, 
 daughter of night, and of her high walled garden full of 
 POISONOUS PLANTS, are sufficient evidence. Concordant 
 
272 
 
 LECTURE 64. 
 
 herewith, modern explorers have found most savage races in 
 possession of poisons and narcotic remedies. 
 
 2. Even the SPECIFIC ACTION OF POISONS was known 
 to the ancients, partly studied by experiments on condemned 
 criminals or slaves. The most famous instance of this knowl- 
 edge we read in Plato’s account of the tests made by the exe- 
 cutioner on Socrates, verifying his prediction of the action of 
 the fatal cup by which the civilized Greeks relieved them- 
 selves of their greatest teacher. 
 
 3. Besides, most races of men have become addicted to the 
 use of some potent plant as STIMULANT OR NARCOTIC. 
 Poppy in the eastern hemisphere. Tobacco in the western 
 world. Tea in China, Coca in South America; Coffee in 
 Abyssinia, Chocolate in Mexico. The pure wines of the 
 Ancients of our own race have been fortified in the destructive 
 spirits manufactured by their descendants. 
 
 4. The dominant race, in its conquest of the continents of 
 the West and South, PAYS TRIBUTE to China for tea, to 
 America for tobacco, and has planted the coffee tree wherever 
 it will grow. The cultivation, transportation and distribution 
 of these apparently useless plants has become an important 
 factor in the economy of nations. In reality they must supply 
 a legitimate want. 
 
 5. The remarkable action on the system, depending in its 
 character on the amount taken, has always been well known, 
 but too often disregarded. In MINUTE DOSES, strychnine is 
 a valuable remedy, but already half a grain may kill under 
 horrible convulsions. Opium, in small doses, relieves the 
 sick of pain ; habituation to larger doses, stupefies the mind 
 and kills the body. These substances evidently are like 
 knives and guns, requiring skill and understanding for their 
 proper use. 
 
 6. Many of these active vegetable materials have never 
 been employed except as remedies. The bark of the CIN- 
 CHONA trees of the Andes were so used against fevers by the 
 
VEGETABLE BASES. 
 
 273 
 
 natives, who imparted this knowledge to their conquerors. 
 The process of gathering the bark (p. 52) being destructive, 
 cinchona plantations have been established in the Dutch and 
 English colonies of India. Rational cultivation and harvest 
 now supply the valued bark at reasonable rates. 
 
 7. Until 1817 the active principles of these remarkable 
 substances remained unknown. FREDERICK SERTUERNER, 
 a pharmacist of northwestern Germany, had already in 1805 
 separated the “principium somniferum” of opium, the inspiss- 
 ated juice of the poppy, and also extracted, by Scheele’s pro- 
 cess, meconic acid from the drug. But hardly any attention 
 was paid to his results ’till in 1817, he published his method 
 of extracting morphine from opium. 
 
 8. Sertuerner treated opium with dilute acetic acid, precip- 
 itated the filtered solution with ammonia, and purified the pre- 
 cipitate by crystallizing it from its solution in hot alcohol; this 
 substance he called MORPHINE. It forms white, slender pris- 
 matic crystals, permanent in air, very bitter; scarcely soluble 
 in water, ether or benzol, moderately soluble in alcohol, 
 especially when warm, and readily soluble in purified fusel oil. 
 
 Morphine crystals are identified by turning orange red with 
 nitric acid, and blue with neutral ferric chloride. 
 
 9. THIS MODE OF EXTRACTION proves morphine to be 
 a base, brought into solution by acetic acid, and precipitated 
 by ammonia because it is insoluble in water. With acids it 
 forms definite salts, generally soluble in water, from which 
 they can be obtained in crystal form. They are insoluble in 
 most organic solvents. Resembling the alkalies, morphine is 
 called an alkaloid. 
 
 10. Nearly all the plants referred to above contain active 
 principles of this kind, or ALKALOIDS. They are EXTRACTED 
 from the crude drug by a like process, modified according to 
 the special solubility of the alkaloids; they are distinguished 
 or IDENTIFIED most generally by some specific color reaction. 
 This important subject can hardly be studied with profit ex- 
 cept in the laboratory course. 
 
274 
 
 LECTURE G5. 
 
 11. Nux vomica contains the alkaloid STRYCHNINE, very 
 soluble in chloroform. It is identified by remaining white 
 (colorless) with concentrated sulphuric acid, and striking a 
 deep blue color with a crystal of potassium bichromate, drawn 
 through the acid film covering the strychnine crystals. This 
 blue color almost instantly changes to deep blueish violet, 
 which gradually passes into an indefinite reddish tint. See 59, 7. 
 
 12. The ALKALOIDS of tobacco (nicotine) and of hemlock 
 or conium maculatum (coniine) are VOLATILE liquids; hence 
 they can be obtained by distilling the drug with dilute potass- 
 ium hydrate. The impure distillate, made alkaline with po- 
 tassium hydrate and shaken with ether, will yield the alkaloid 
 on spontaneous evaporation of the ethereal solution. Coniine 
 is distinguished by its strong, mousy odor. Hemlock infusion 
 was the poison cup of the Greeks; see 2. 
 
 65. NEUTRAL PRINCIPLES. 
 
 1. ' Many plants yield to neutral solvents, such as water 
 and alcohol, crystalline substances destitute of marked acid 
 or alkaline properties; such substances are called neutral 
 principles. Some of these principles resemble alkaloids, others 
 seem to act like acids. Most have a marked taste, especially 
 bitter or astringent, and some act powerfully on the system 
 (cathartics). 
 
 2. THE BARK OF THE WILLOW imparts an intense red 
 color to sulphuric acid. Poured into water, the diluted acid 
 gradually becomes colorless, depositing a dark red precipitate. 
 These reactions are due to salicin, which may be extracted by 
 boiling the bark with milk of lime, evaporating the clear, 
 decanted solution to dryness, and exhausting the residue with 
 weak alcohol ; the salicin will crystallize after the alcohol has 
 been distilled off. 
 
NEUTRAL PRINCIPLES. 
 
 3. SALICIN crystallizes on cooling from hot solutions in 
 water or in alcohol, forming white, silky needles, permanent 
 in the air; it is odorless, very bitter; its solutions have a 
 neutral reaction. F 198. It has been used as a febrifuge. 
 
 It is identified by the above given reaction with sulphuric 
 acid and water. Heating a small portion with the chromic 
 oxidizing mixture (bichromate and sulphuric acid), the char- 
 acteristic odor of the oil of meadow sweet (spiraea ul maria) 
 will be noticed. 
 
 4. When salicin is boiled with dilute sulphuric acid, the 
 solution will, after neutralization, give the glucose reaction 
 with Fehlings reagent (58.7); accordingly, glucose has been 
 formed from salicin. Special researches have shown that 
 there also forms the compound, saligenin, and that water 
 has been taken up. Substances which take up water and 
 yield glucose, are called GLUCOSIDES. 
 
 5. The flower heads of Artemisia paucitlora are sold under 
 the name of Santonica (Levant Wormseed). Mixing the 
 ground “wormseed” with slacked lime, and exhausting the 
 mixture with hot water, the concentrated filtrate yields crude 
 SANTONIN as precipitate on the addition of muriatic acid. 
 The product may readily be purified and crystallized from 
 alcohol. It turns yellow by exposure to light. It acts like a 
 feeble acid. It is a noted anthelmintic. 
 
 6. The kernel of Cocculus Indicus is bruised and extracted 
 with hot alcohol ; this solution is concentrated to a thick, 
 syrupy consistence (removing separated fat). Boil the 
 residue with water, filter, and set the hot filtrate aside for 
 crystallization. The crude crystals, purified by recrystalliza- 
 tion from alcohol, are PICROTOXIN. It is a bitter glucoside, 
 extremely poisonous. 
 
 7. The inspissated juice of the leaves of several varieties 
 of Aloes are quoted in the drug market under the name of 
 Gum Aloes. When Barbadoes aloes is treated with ten times 
 
276 
 
 LECTURE 65. 
 
 its own weight of water (slightly acidified with muriatic acid), 
 the liquid decanted after cooling, and evaporated to about 
 double the weight of the gum taken, crystals will slowly form 
 (in a week or two). This is ALOIN (barbaloin). It is 
 extremely bitter; in small doses (2 cgr) a laxative, in larger 
 doses (10 cgr) a cathartic. 
 
 8. The inner bark of Quillaja Saponaria of South America 
 contains the glucoside SAPONIN, which is extracted by hot 
 water. Its aqueous solution froths when agitated, like soap- 
 suds; the froth is very slow to settle. Medicinally it is an 
 irritant diuretic; technically it is used to cleanse silk. It is 
 also used as an adulterant to foaming liquids. 
 
 9. THE TANNING OF HIDES to form leather is one of the 
 oldest industries. The cleaned animal hide decays (putrefies) 
 rapidly; but if packed in white oak bark, it slowly changes to 
 leather, which is quite permanent in both air and water. 
 
 The active principle of the oak bark is called tannin. It is 
 best extracted from nut galls, which contain fully half their 
 own weight of tannin. 
 
 10. Powdered NUT GALLS are extracted in various ways 
 with water and ether; the water dissolving the tannin, the 
 ether taking up the impurities from the solution. The liquids 
 are separated, the aqueous solution concentrated and spread 
 to dry on glass or tin plates to obtain the TANNIN as a yellow- 
 ish, non-crystallizable powder. It is very soluble in water and 
 dilute alcohol, but almost insoluble in absolute ether. 
 
 11. The taste of tannin is strongly astringent. Its solution 
 precipitates most solutions of animal materials, especially 
 gelatin and albumin; hence its use in tanning. It also pre- 
 cipitates most salt solutions, and forms with ferric solutions a 
 black precipitate; ferrous solutions turn black on exposure to 
 air (ink). Tannin acts like a feeble acid, but has been 
 generally considered a glucoside. 
 
 12. Aqueous solutions of tannin, exposed to the air, undergo 
 GALLIC FERMENTATION, due to the presence of the complex 
 
NEUTRAL PRINCIPLES. 
 
 277 
 
 ferment penicillium glaucum. Glucosides present yield glu- 
 cose which, after the gallic fermentation is completed, give 
 alcohol. 
 
 Tannin is one of the most common vegetable products, 
 contained in most barks and leaves. It is recognized by its 
 astringent taste and its reaction with ferric solutions or with 
 gelatin. 
 
 66. STARCH AND FIBER. 
 
 1. Thus far we have by the simplest methods possible ex- 
 tracted our organic prime materials from plants, especially by 
 pressure, heat and solvents. The insoluble residue left in all 
 these cases constitutes the main body of the plant. This re- 
 sistant material gives each plant its characteristic form. It is 
 called woody fiber or CELLULOSE. 
 
 2. The microscope shows the wood cell to be essentially 
 cylindrical in form, varying greatly for different tissues in the 
 same pknt and for corresponding tissues in different plants. 
 By treating the crushed and broken tissue in succession with 
 the solvents used to extract the vegetable principles studied, 
 the WOODY FIBER will remain as a white, fibrous mass, 
 insoluble in water, alcohol, ether, dilute alkali and acid. 
 
 3. This woody fiber may be extracted from almost any 
 plant with more or less labor; we find it, however, quite 
 pure in COTTON, the fiber of which, under the microscope, 
 appears as twisted ribbons. The so-called absorbent cotton 
 is obtained by removing the small amount of fatty material 
 present in raw cotton. Linen, the smooth, round fiber of flax, 
 is also very pure cellulose. 
 
 4. In wood proper, the true cellulose is thickened with 
 LIGNIN, which is brittle. It can be removed by treating the 
 properly divided wood with lime saturated with sulphur dioxide 
 under pressure (2 to 3 atmospheres). This givesthe WOOD- 
 
278 
 
 LECTURE 66. 
 
 PULP, so much used for lower grades of paper, and largely 
 imported from Norway and Germany. Phloroglucin and con- 
 centrated muriatic acid turn lignin intensely purple-red; hence 
 white paper can be tested for lignin by this reagent. 
 
 5. Cellulose can be dissolved by Schweizer’s reagent; an 
 ammonical solution of cupric hydrate. Cellulose is re-precipi- 
 tated by acids, forming a white amorphous powder, purified by 
 washing with alcohol. 
 
 Some animals (Ascidia) contain a corresponding material 
 Tunicin (animal cellulose) ; in its solubilities it closely 
 resembles true cellulose. 
 
 6. THE IMPORTANCE OF CELLULOSE TO MAN can 
 hardly be expressed in words. Man has dressed himself in 
 linen and cotton ; coarser fibers he uses for sacks and cordage. 
 When these are worn out — rags — he makes paper thereof. 
 Of the wood itself he builds houses and ships, and also burns 
 it for comfort and power. But above all, woody fiber gives 
 form to plants — the beautiful mantle of the globe. 
 
 7. If we examine a thin slice of almost any tuber or seed, 
 we find the cells of the tissue to contain smaller globular 
 cells, called STARCH. If the ground or crushed material is 
 washed on a sieve or straining cloth, the starch runs through 
 the cloth with the water, and gradually settles in the receiv- 
 ing vessels. 
 
 8. STARCH GRAINS show concentric layers around a 
 nucleus (hilum) in the center or near one end of the grain. 
 The form, while in the main globular, shows specific modifi- 
 cations for each plant, as well as characteristic dimensions, so 
 much so that in many cases the plant can be named from a 
 microscopic examination of the starch. 
 
 9. POTATO starch is the largest (60 to 100 microns), 
 somewhat egg-shaped, the excentric hilum and rings readily 
 distinguished. RICE starch is among the smallest (3 to 7 
 microns), the grains showing polygonal forms. WHEAT starch 
 
STARCH AND FIBER. 
 
 279 
 
 (20 to 30 microns), is larger than CORN starch (15 to 20 
 microns) ; the former is spherical, the latter somewhat poly- 
 hedral. A micron is the thousandth part of a millimeter; it 
 is the unit of microscopic measures. 2, 5. 
 
 10. STARCH is insoluble in (cold) water, but soluble in 
 strong solutions of zinc chloride, calcium chloride and similar 
 salts. Starch is also insoluble in alcohol. 
 
 When starch is heated with water, the grains swell and 
 burst, giving, on boiling, starch paste. Alcohol precipitates 
 herefrom soluble starch as a white powder, soluble in cold 
 water. In the paste, the membranes remain as shreds; the 
 cell-contents (granulose or amidin) only has dissolved. Iodine 
 is a most delicate reagent for starch (23.4). 
 
 11. Starch, being one of the principal constituents of 
 FLOUR, is a valuable food. The roller process — like the mill 
 stones of the ancients — crushes the grain without tearing it; 
 but excessive bolting produces a very white, insipid flour con- 
 taining an undue proportion of starch. Potatoes are the 
 poorest, wheat is the most nutritive; corn contains most fat, 
 rice the least of fiber. 
 
 12. STARCH being required in many industries (textile, 
 paper, glucose) it IS MANUFACTURED in enormous quantities. 
 In Germany starch is largely extracted from potatoes; in Rus- 
 sia, from wheat; in the United States, from corn (maize), and 
 in England from (imported) rice. From the tropics we get 
 arrow- root and genuine sago, which resembles potato starch 
 somewhat; accordingly the tuber sometimes is sold where the 
 palm is called and paid for. 
 
 67, MILK AND BUTTER. 
 
 1. Milk is the food of all young mammals; to man it is a 
 valuable food throughout his entire existence. The most 
 abundant and cheapest source is THE COW (p. 49) ; the best 
 product is obtained from cows in good pasture. “The old 
 
280 
 
 LECTURE 67. 
 
 pastures” on which no plow has drawn furrow for centuries, 
 extending on the west coasts of Germany from Holland to 
 Sleswig, and protected by dykes from the sea, furnish milk in 
 flavor and richness unsurpassed. 
 
 2. THE PRODUCTION OF MILK occupies a prominent 
 place in the economy of nations. The entire money value of 
 the production of gold is insignificant when compared to the 
 market value of the golden butter produced throughout the 
 world in the same time — and yet butter is only one of the 
 products of milk, though the one that most extensively enters 
 commerce. 
 
 3. MILK is chemically a very complex liquid, and in its 
 nature PERISHABLE. After evaporation in vacuum pans, with 
 the addition of sugar, it can be shipped far and kept for a long 
 time. By freezing it has also been shipped, especially from 
 Denmark to England. But the most rational course consists 
 in the shipment of the two most valuable and permanent pro- 
 ducts, butter and cheese, and to use the balance for food on 
 the farm. 
 
 4. THE PROXIMATE ANALYSIS of milk has been practiced 
 from time immemorial; upon it rests the milk industry. By 
 simply allowing milk to stand in a cool place, its lightest parts, 
 CREAM, rise to the surface, forming a layer of about one-tenth 
 the depth of the milk. This cream, after ripening, yields 
 BUTTER by simply churning. The skim-milk, on spontaneous 
 or artificial acidification, yields CASEIN (cheese) ; the whey 
 left gives, upon concentration, milk sugar (LACTOSE) in 
 crystals, and SALTS (potassium phosphate, chloride) as 
 residue. 
 
 5. By the introduction of modern CENTRIFUGAL SEPAR- 
 ATORS, the stream of fresh milk flowing into the machine 
 comes out in two continuous streams, namely, the lighter cream 
 from the inner, the heavier skim -milk from the outer sheet. 
 The Laval separator makes fully one hundred revolutions a 
 second, thus instantly separating milk into its two layers for 
 which the less intense gravity requires twenty-four hours. 
 
MILK AND BUTTER. 
 
 281 
 
 G. The microscope shows that milk is an (opaque, white) 
 EMULSION; a transparent, aqueous solution holding minute 
 fat (butter) globules in suspension. These globules are 
 each covered with a thin film, which readily yields to alkalies, 
 after which the ether will dissolve the fat and leave it upon 
 spontaneous evaporation. While not the most exact, this is 
 the most instructive determination of the per cent, of butter 
 in milk. 
 
 7. By such processes it has been ascertained that GOOD 
 COW MILK contains about 13 per cent, of the four solids con- 
 stituents specified; the balance (87 per cent.) being water. 
 The percentage of the four solids averages as follows: fat, 4 
 (butter); sugar, 5 (lactose); curd, 3j (casein), and salts, h 
 Human milk contains about one per cent, more of sugar (6) 
 and one per cent, less of casein (2j); it is more sweet and 
 much more easily assimilated than cow’s milk. 
 
 8. FRESH MILK is sweet and faintly alkaline; G 1.03. 
 By exposure it becomes acid; LACTIC ACID forming (best 
 between 25 and 35 degrees). In proportion as this acid forms, 
 the casein is precipitated (coagulated). After straining and 
 washing, this CRUDE CASEIN may be purified by dissolving 
 it in a strong solution of sodium carbonate at a moderate tem- 
 perature. After removing fats, and other impurities, the 
 casein may be obtained by precipitation with an acid, and 
 washed with water, alcohol and ether. 
 
 9. CHEESE consists mainly of the casein of milk. If made 
 from skim-milk, the cheese is hard, almost like a brick; it is 
 said, “dogs bark at it, hogs grunt at it, but neither dare bite 
 it.” Made from whole milk, it retains all the fat, and is both 
 palatable and nourishing. By various additions and peculiar 
 processes of ageing, numerous varieties of cheese are pro- 
 duced. Some districts are famous for their special brands of 
 cheese that bring deservedly a high price in the market. 
 
 10. BUTTER is the most complex and the most easily 
 assimilated fat known; hence the high price it brings, and 
 
282 
 
 LECTURE 68. 
 
 hence also the multiform attempts to imitate it. Genuine 
 butter has a specific aroma and rich golden color; G 0.94, F 
 31, solidifying at 20. It contains 56 per cent, solid fats 
 (stearin and palmitin), 36 per cent, of olein, and 8 per cent, 
 of butyrin with certain other light fats and flavoring ingredients 
 well known to the connoisseur, but not scientifically defined. 
 
 11. The real VALUE OF BUTTER depends upon the judg- 
 ment and taste of the consumer; if the consumer does not 
 know good butter from indifferent or bad, or genuine from 
 spurious, he will be satisfied with the low grades and imita- 
 tions. The chemist can only detect rather glaring frauds. 
 When we come to the study of the fatty acids, we shall learn 
 to understand this. 
 
 12. Since 1870, the market is flooded with ARTIFICIAL 
 BUTTERS, including ox-butters, hog-butters and worse. The 
 term butter having an established signification, its use for any 
 chemical imitations is in its very nature fraudulent; legislation, 
 even in Germany, is now beginning to recognize this fact. 
 But specially feeding cows low grade fats (cotton seed oil 
 cakes, etc., etc.) adds to fraud the contemptible attempt to 
 make the innocent cow a particeps criminis. 
 
 68. FLESH AND BLOOD. 
 
 1. The highest material life on the globe is represented by 
 the warm blooded animals. Man has taken their flesh as food; 
 first as a hunter, next as herdsman, and now as farmer. 
 The domestic animal occupies a conspicuous and most im- 
 portant place, both in the permanence of soil fertility and in 
 the immediate financial rewards. THE WEALTH OF modern 
 NATIONS, as was that of the patriarchs, is largely represented 
 in the number of their cattle. 
 
 2. The primitive process of drying, salting and smoking, 
 permit the PRESERVATION OF perishable MEATS beyond the 
 
FLESH AND BLOOD. 
 
 283 
 
 day of procurement and thus also their entrance in the com- 
 merce of the world. The modern process by refrigeration 
 permits transcontinental and oceanic shipment of so-called 
 “fresh meats;” but the product suffers really more than by 
 the older methods. It has built up great trusts, depressed both 
 local industry and agriculture, and is fast depriving the rising 
 generation of the knowledge of genuine beef. 
 
 3. The old sage said BLOOD IS THE LIFE OF THE FLESH 
 (Gen. 9, 4) ; modern investigations have fully substantiated 
 this statement. Blood is the most wonderful liquid of nature. 
 Our scientific methods are crude when applied to this liquid; 
 in modern days we have, through the investigations of 
 PASTEUR (p. 31) and his disciples, obtained many demon- 
 strations of the Mosaic statement. 
 
 4. BLOOD is a most complex liquid, G 1.05 — 1.07; its 
 odor is specific, varying with the animal. In every (warm 
 blooded) animal blood presents two strikingly different modi- 
 fications: bright red in the arterial system, flowing from the 
 heart to the substance of the flesh, and darker, blueish in the 
 return current of the venous system. Each of these modifi- 
 cations shows its own specific absorption spectrum between 
 D and E (52, 12). 
 
 5. A small drop of blood, spread out by the cover glass, 
 shows under a good microscope, a multitude of minute disk- 
 like GLOBULES or CORPUSCLES. In human blood there are 
 about five millions of globules to the droplet (of one cubic milli- 
 meter), each globule being 8 microns in diameter and 2 
 microns thick. In most mammals the globules are also circu- 
 lar disks. In birds, reptiles and fishes their form is elliptical, 
 and often much larger than in man. In frogs their larger 
 diameter is 22 microns. 
 
 6. Freshly drawn blood, left standing in a glass cup, gradu- 
 ally separates into the semi-solid, red CLOT and the pale- 
 yellow liquid SERUM. The clot (on washing) leaves white 
 FIBRIN; in the water the globules settle like starch. The 
 
284 
 
 LECTURE 68. 
 
 serum will also coagulate when exposed long enough. Human 
 blood contains 12.7 per cent, of globules, and 0.3 per cent, 
 fibrin in the clot, and 7 per cent, albumin in the serum ; total 
 20 per cent, solids, and 80 per cent, water. 
 
 7. Serum, when gently heated, coagulates ; the whitish solid 
 is mainly ALBUMEN. The white of eggs shows the same de- 
 portment to heat. The albumens are distinguished as egg- 
 and serum-albumen. They differ slightly, especially in their 
 resistance to a rise in temperature. Egg albumen coagulates 
 more readily (at a lower temperature) than serum -albumen. 
 Methods of purification cannot here be given. 
 
 8. The blood globules are covered with a thin fibrinous 
 membrane, and consist of red HEMOGLOBIN and the 
 albumen -like substance globulin in the proportion of about 
 8 to 1. Haemoglobin is the real coloring matter of the blood. 
 Shaking fresh blood in a flask with a small amount of ether, the 
 globules are broken up ; when the flask is set aside for a night 
 in the cold (best in melting ice) crystals of haemoglobin will 
 be found on the walls of the flask. The crystals contain iron. 
 
 9. A dilute acqueous solution of haemoglobin ABSORBS 
 OXYGEN gas, and becomes brilliant red, showing two dark 
 absorption bands one each near D and F. Any REDUCING 
 GAS drives out the oxygen, the color changes to that of dark 
 blood, and a broad absorption band appears midway between 
 D and E, instead of the two bands characterizing the red or 
 oxyhemoglobin. These changes can be exhibited repeatedly 
 in succession. 
 
 10. The blood also contains MINERAL MATTER, left upon 
 incineration. The clot gives mainly iron and potassium com- 
 pounds; both leave phosphates and chlorides. The serum 
 gives sodium salts. 
 
 Salt solutions exert a remarkable effect on blood. Blood 
 run into ten times its own volume of a 2 per cent, salt solution 
 does not coagulate; the globules settle to the bottom of this 
 mixture. 
 
FLESH AND BLOOD. 
 
 285 
 
 11. The muscular tissue is built up from blood; the mus- 
 cular fiber is related to fibrin. Again, the used up parts are 
 removed by and in the blood, partly serving a further purpose 
 in the hepatic system (BILE) in aid of digestion, partly being 
 removed through the kidneys (URINE), skin (PERSPIRATION) 
 and lungs (RESPIRATION). We shall very briefly consider 
 the chemical processes involved in a subsequent lecture. 
 
 12. Albumen, fibrin and casein, as well as their modifica- 
 tions, are called albuminoid substances, also PROTEIDS, 
 nitrogenous substances, plastic food, etc., etc. Singeing 
 them, they emit the characteristic odor (I, 5). They are 
 extremely prone to change. We distinguish them mainly 
 by their most common mode of solidification or coagulation ; 
 albumen by heat, casein by acids, and fibrin by mere exposure 
 to the air. 
 
 69. BONE AND SINEW. 
 
 1. The deep contains animals depending on the sur- 
 rounding medium for support and even form; their body 
 consisting of flesh and blood only. But all higher animals, 
 from the fish of the sea to the bird of the air, have their flesh 
 connected by strong SINEWS to a frame work of BONES, 
 whereby they show infinitely varied beauty of form and per- 
 fection of mechanism. 
 
 2. The dominant form of bone is the TUBE. Galilei has 
 shown this form to be the most economical, giving the greatest 
 possible strength for the amount of material employed. The 
 material itself is also most perfect, being a living tissue of 
 mineral (S) and organic (i) matter, possessing both STRENGTH 
 AND ELASTICITY in a high degree. 
 
 3. The mineral matter of a bone is dissolved in dilute (10 
 per cent.) muriatic acid in the course of a few days. The 
 liquid shows mainly calcium phosphate (85 per cent.) and 
 
286 
 
 LECTURE 69. 
 
 carbonate (11 per cent.); the balance being about equally 
 calcium fluoride and magnesium phosphate. The well washed 
 organic material, OSSEIN, retains the form of the bone used, 
 but is flexible and elastic, so that it may even be tied in a 
 knot. • 
 
 4. Boiling ossein in water, converts it into GELATIN, 
 which is soluble in hot water, but solidifies to a jelly upon 
 cooling. When the gelatin solution is so dilute that it does 
 not set to a jelly on cooling, an aqueous solution of tannin 
 will give a most characteristic, white flocculent precipitate. 
 Alcohol also precipitates dilute solutions of gelatin. 
 
 5. The white fibers of connective tissue (sinews and ten- 
 dons) are mainly composed of COLLAGEN, that is, a substance 
 which changes the gelatin when boiled with water. When 
 connective tissue is treated with acetic acid, the white fibers 
 swell up and become transparent, while the elastic fibers 
 (elastin) remain unchanged and can be seen distinctly under 
 the microscope. 
 
 6. Gelatins of greatly varying qualities are manufactured, 
 bringing correspondingly different prices. From the low grades 
 of GLUE, the prices run up to divers fine brands of GELATIN 
 for culinary purposes and for clarifying liquids. The purest 
 and most costly is the genuine Russian Beluga ISINGLASS, 
 made from the swimming bladder of certain sturgeons. 
 
 7. When these gelatins had first been extracted, especially 
 from bones under pressure, they were recommended by 
 chemists as cheap and good foods for the poor. These foods 
 were introduced into penal and charitable institutions, to the 
 great disgust of the inmates, whose unsophisticated stomachs 
 were denounced as prejudiced, till the rats in a raid ate all in 
 sight but this “bone soup.” GELATIN IS NO FOOD. 
 
 8. The substance of horn and hoof, feathers and hair, and 
 of the epithelial tissues generally, are less soluble and contain 
 sulphur; when boiled with water under pressure they yield 
 
BONE AND SINEW. 
 
 287 
 
 sulphuretted hydrogen. These substances are called KERA- 
 TINS. From feathers, a brownish-yellow keratin is prepared 
 for coating pills. Such pills are not acted upon in the stomach, 
 and permit the introduction of remedial substances to the 
 intestines. 
 
 9. Silk, the most costly fiber, is manufactured by the silk 
 worm from mulberry leaves. It consists of a smooth, round, 
 thread (fibroin) covered with sericin or silk-glue. The latter 
 is readily dissolved by soap solutions to a sort of glue, while 
 the former resists; both are rapidly dissolved by alkalies, but 
 are much less acted upon by acids. Silk is very hygroscopic. 
 An “artificial silk” is made from collodion. 
 
 10. Bones burnt in an open fire leave about two-thirds of 
 white BONE-ASH. This is used for cupels (7.6) and for the 
 extraction of phosphorus. This method of extraction was first 
 devised byScheele. By sulphuric acid much lime (as gypsum) 
 is removed from the bone ash; the phosphate solution is evap- 
 orated to a syrup, and in two stages reduced by charcoal. 
 
 11. Bones heated with exclusion of the air leave BONE 
 BLACK or animal charcoal, and yield an offensively smelling 
 distillate, Dippel’s oil. The charcoal results from the organic 
 material, the ossein, and retains all the mineral matter. 
 Animal charcoal is a most important absorbent for coloring and 
 odoriferous substances, and hence constantly used as filter for 
 organic liquids in the laboratory and in the arts (sugar 
 refmeges) . 
 
 12. Animal charcoal, having been used, may be REVIVED 
 by first washing it out and then charring it again. This pro- 
 cess is even repeated, on account of the high price of the 
 material. When finally no longer fit, even as admixture to 
 fresh animal charcoal, it may be used as a source of phos- 
 phorus. ' Bones are also utilized by first extracting the fat 
 with benzol, then the ossein with water, and lastly, the 
 phosphorus as indicated above. 
 
70. ANIMAL AND PLANT. 
 
 1. We have seen in what manner the principal prime ma- 
 terials of organic chemistry are extracted from plants and 
 animals, and how they are purified. They yield chemical 
 compounds of perfectly definite chemical and physical prop- 
 erties. 
 
 2. Before we begin a more detailed study of the chemical 
 transformation of these prime materials, it will be advisable to 
 look upon their mutual relations in the GREAT CIRCLE OF 
 MATERIAL LIFE. Air, water and soil we shall find to be the 
 substances, sunshine the power, and the living cell the labora- 
 tory in which this chemical circulation of matter takes place. 
 
 3. PLANTS GROW from seeds. These seeds are very 
 small compared to the plant. The substance of the oak was 
 never contained in the acorn. Burning the wood of the tree, 
 we obtain heat (FIRE) as power, also carbon dioxide and water 
 as material products disappear in the atmosphere; finally a 
 few per cent, of mineral matter (ASHES) remain as visible 
 solids of the wood burned. 
 
 4. This rapid destruction (combustion) of the plant we 
 now know to be the exact opposite of its slow growth. The 
 SUN supplies the heat necessary to unite aqueous vapor and 
 carbon dioxide of the AIR to the combustible material of the 
 plant under separation of oxygen gas; the soil supplies the 
 MINERAL MATTER remaining in the ashes. 
 
 5. Numerous LABORATORY EXPERIMENTS on growing 
 plants in glass cylinders, permitting an accurate determination 
 of the changes effected on the air supplied, have proved this. 
 The effects of mineral matter have been specially studied by 
 growing plants (beans, Indian corn, etc.) in dilute solutions of 
 accurately known mineral composition (Sachs), confirming the 
 earlier chemical results (Liebig, p. 23) on ashes and soils. 
 
ANIMAL AND PLANT. 
 
 ■289 
 
 6. That growing PLANTS EXHALE OXYGEN GAS can 
 readily be seen by examining the gas accumulating over any 
 green foliage under water and exposed to the sun light. A 
 simple funnel suffices to hold the foliage. The gas accumu- 
 lating in the stoppered neck of the funnel re-kindles a glow- 
 ing shaving when the stopper is withdrawn. It is oxygen. 
 
 7. The comparatively small amount of nitrogenous material 
 produced in the plant (especially stored in its seeds) has been 
 traced, in like manner, to the AMMONIA of the air and in the 
 soil. Hence the beneficent effects of animal manures. The 
 fertility of the soils of Europe is sufficiently enhanced by 
 guano to warrant the importation thereof from the opposite 
 extremity of the globe. 
 
 8. The herbivorous and grain eating animals depend for 
 their food entirely on the plants; even carnivorous animals do 
 so, because their prey subsist on plant food. But animals 
 require equally a pure air, rich in ox^/gen, for respiration. 
 Without VEGETABLE FOOD, animals slowly starve to death; 
 without OXYGEN, they die promptly from suffocation. 
 
 9. Throughout the system of the animal, the absorbed 
 vegetable food (chyle) and the oxygen of the air unite chem- 
 ically; the red blood becomes dark from the products of this 
 combination.- In the LUNGS the carbon dioxide is sent back 
 to the atmosphere (16. 9). In the KIDNEYS the products of 
 the combination of nitrogenous substances or proteids are 
 separated (urea, uric acid). The SKIN largely removes the 
 water in prespiration. Undissolved food RESIDUES are evacu- 
 ated as feces.— See blackboard diagram. 
 
 10. The union of the vegetable food with the oxygen of 
 the air throughout the system constitutes a real wet-way 
 combustion, and produces the HEAT AND MUSCULAR POWER 
 -of the body. The first experimental researches in this field 
 were made by Lavoisier (p. 19). Grimaux has published two 
 most instructive plates in his Life of Lavoisier, showing these 
 remarkable experiments. 
 
290 
 
 LECTURE 71. 
 
 11. It is evident that animal life contains within itself the 
 CAUSES OF ITS OWN DESTRUCTION or death. The air 
 exhaled poisons the atmosphere. In a like manner, the other 
 products of animal life are poisonous to such life. While 
 plants are less sensitive, vegetable life alone would also pro- 
 duce conditions destructive to itself. 
 
 12. Thus, not only does animal life depend upon plants for 
 food, but even for constantly destroying the poisonous effects 
 of animal life on itself and its surroundings. In a like manner 
 animal life makes it possible for vegetation to flourish. The 
 two forms of life supplement each other to one grand circle of 
 chemical and physical transformations, depending for its 
 permanence on that of the sun. 
 
 71. FERMENTATION AND LIFE. 
 
 1. Bread and wine have nourished and refreshed man from 
 the earliest times. Both substances involve chemical processes 
 of great mystery. The grain and the grape furnished by 
 plant-life, have undergone an additional chemico-vital process 
 before they became fit for food. This process is FERMEN- 
 TATION. 
 
 2. Moses prohibited the use of leavened bread during the 
 exodus. It was also prohibited in burnt meat offerings. 
 These are probably the oldest historic records of LEAVEN. 
 The wonderful rapidity wherewith “a little leaven” changes 
 a large amount of meal, is used repeatedly as a striking 
 figure in the new testament. The fermentation of grape juice 
 was practiced as far back as the flood. 
 
 3. Van Helmont (p. 30) is the first modern investigator 
 who reached a fair conception of the importance of fermentation 
 in the economy of nature; he rightly compared VITAL 
 PROCESSES in health and disease to fermentation. The 
 microscope afterwards showed the presence of special cells in 
 
FERMENTATION AND LIFE. 
 
 291 
 
 leaven and ferment. But even Liebig (1870) considered these 
 cells non-essential to the chemical process going on. 
 
 4. It is Pasteur (p. 31) who has discovered the true 
 function of ferments in nature’s household. In fermentation 
 we have the life process of the cell. The ferment cell feeds 
 on glucose; the products of its vital act are carbon dioxide and 
 alcohol. To grow, the ferment cell requires nitrogenous food 
 and salts, as do higher plants. Pure glucose solution will not 
 ferment. 
 
 5. TFIE GERMS of ferments float in the air. Solutions, 
 sterilized by boiling in glasses loosely stoppered with cotton, 
 will not ferment; the germs possibly present being killed by 
 the heat, and germs from the air being stopped by the cotton. 
 Even a downward bent neck prevents the germs from falling 
 into the flask. There is no spontaneous generation. Thus 
 Pasteur in the sixties. — Tyndall strikingly showed the germ 
 filtering effect of cotton on air. The nose is such a germ filter 
 for our own lungs. 
 
 6. The most common ferments for wine, beer and bread 
 are globular or elliptical, acting on the saccharine substanses; 
 hence they are called SACCHAROMYCES. The beer yeast 
 contains the S. cerevisiae, consisting of almost spherical cells, 
 growing by budding while young, forming nuclei when old 
 (see plate). The wine ferment, S. ellipsoideus, is named 
 after the elongated form of its cells. 
 
 7. At common temperatures (16 to 20 degs.) beer wort 
 ferments rapidly, the yeast rising to the SURFACE. At lower 
 temperatures (6 to 8 degs.), the wort ferments slowly, requir- 
 ing weeks instead of days; the yeast collects at the BOTTOM. 
 The beer produced in the latter case is called lager. The 
 ferment of surface fermentation differs from that of bottom 
 fermentation. Both are present— but each grows best at its 
 own temperature. 
 
 8. Beer or light wine exposed to air becomes sour; acetic 
 acid is formed, due to the growth of BACILLUS ACETICUS, 
 
292 
 
 LECTURE 71. 
 
 which thrives best (optimum) between 18 and 35 degrees, 
 and requires air (aerobic ferment). The souring of milk is 
 due to the formation of lactic acid from its lactose; this change 
 is due to the growth of BACILLUS ACIDI LACTICI, which 
 requires no air (anaerobic ferment) and thrives best between 
 35 and 40 degrees. (See plate). 
 
 9. The life process of ferments limits itself by AUTOTOXY, 
 precisely as does the life process of true plants and animals. 
 When 10 to 12 per cent, (by weight) of alcohol has been 
 produced in the glucose solution, the cells cease growing; 
 when 14 per cent, are present, the ferment is killed by its 
 own product. The most favorable tem.perature for the growth 
 of the ferment cells is between 28 and 34 degrees (the opti- 
 mum). In concentrated glucose solutions (over 60 per cent.) 
 the cells cannot live. 
 
 10. Pasteur has also proved that certain contagious and 
 infectious DISEASES are fermentative; and that the system 
 may be protected against the growth of these ferments or 
 microbes by VACCINATION. The immunity enjoyed by our 
 race against smallpox, since Jenner’s day, can now be under- 
 stood. The microbe is attenuated (weakened) by culture 
 under unfavorable conditions; the liquid (serum) so produced 
 may confer immunity to the system to which it is transferred 
 (by inoculation, vaccination). 
 
 11. Medical research of the present is almost entirely 
 dominated by the METHODS OF THE CHEMIST PASTEUR. 
 Microbes, toxins, antitoxins, serums are the watchwords of 
 the day and the chemist properly surrenders this new world 
 to the physician and the biologist. But the new compounds 
 produced — corresponding to alcohol in common fermentation — 
 remain in the chemical laboratory. 
 
 12. Thus, many of these microbes produce alkaloidal 
 compounds. If formed during life of the macro-organism, 
 these compounds are called LEUCOMAINS (Gautier) ; if in the 
 cadaver, they are called PTOMAINES, (Selmi). Several of 
 
FERMENTATION AND LIFE. 
 
 293 
 
 these latter simulate the solubilities and color reactions of the 
 true vegetable alkaloids, strychnine, quinine, and others, and 
 thus impose extra care on the part of the toxicologists. The 
 former also show a like kinship; the leucomains xanthin and 
 uric acid give the same murexid test as do theobromine and 
 caffeine (theine). This may account for the general use of 
 tea, coffee and chocolate. 
 
 72. PETROLEUM AND COAL. 
 
 1. Plants and animals have lived on this globe for ages; 
 we find their imperishable remains in all stratified rocks (12). 
 Such remains are called FOSSILS and casts, according as it is 
 the original material (shell, coral, bone), or the same replaced 
 by some other substance (silica). 
 
 2. Many limestone deposits are almost completely made up 
 of shells and corals, due to the respiration of mollusks and 
 polyps of the primeval sea. These enormous limestone de- 
 posits thus contain the carbon dioxide of the PRIMEVAL 
 ATMOSPHERE, which must have been utterly irrespirable to 
 warm blooded animals. 
 
 3. In such an atmosphere, vegetation must have been ex- 
 cessively luxuriant. The numerous coal deposits found in all 
 parts of the globe confirm this conclusion by their extent and 
 thickness; for COAL is the fixed residue of primeval vegeta- 
 tion, terrestrial and aquatic. Enclosed between two layers of 
 rock, the vegetable material would mainly lose volatile con- 
 stituents and become richer in carbon (carbonized). 
 
 4. Chemically we can distinguish only two kinds of coal, 
 namely, BROWN -COAL and bituminous or BLACK-COAL, 
 The first gives an acid distillate (acetic acid) ; when heated in 
 a test tube, a moist blue litmus paper is reddened by the 
 vapors. The second gives a strongly alkaline (ammoniacal) 
 distillate. Anthracite seems to be the end-product of bitu- 
 minous coal. 
 
294 
 
 LECTURE 72. 
 
 5. Mohr, the systematize!' of volumetric Analysis (50, 1), 
 found that wood and peat yield acid distillates, while dried 
 sea weeds yield an alkaline distillate. He concluded that it 
 is chemically impossible to derive bituminous coal from wood or 
 peat; that this coal must have formed in the ocean from SEA 
 WEEDS and still continues so to form to-diy (Sargossa Sea of 
 the Atlantic) . 
 
 My own observations and analyses (48, 10) have confirmed 
 the conclusions of Mohr. However, geologists continue to dis- 
 regard the apparent chemical impossibility involved in their 
 favorite theory of the origin of coal from trees of primeval 
 forests and from peat bogs. 
 
 6. Chemically coal is a prime material of the utmost im- 
 portance (12, 10). It forms the basis of most extended 
 chemical industries. GAS WORKS yield tar, ammonia, 
 cyanides and other products. The use of coal as fuel — and 
 source of steam power — ^may be again replaced by water 
 power, which, converted into electricity, may be widely dis- 
 tributed, as is being done at the present (Niagara). 
 
 7. AT Baku, on the Caspian Sea, fire worshipers have 
 maintained permanent fires from time immemorial. Over 
 quite an extended region it is sufficient to dig or drill down a 
 few feet into the ground to obtain a flow of gas that burns 
 upon being lit. The Chinese have for centuries utilized such 
 ho-tsings (tire-springs) in connection with their salt works. 
 
 8. Shortly before 1860, PETROLEUM was discovered in 
 enormous quantities in Pennsylvania, and promptly refined 
 for the market of the world as illuminating oil (KEROSENE). 
 New wells were drilled, great fortunes were made, and oil 
 fields sought for in other States. New York, Ohio, Canada 
 and California have added to the production. 
 
 9. The example of America found imitators in the Baku 
 region, which now is commercially highly developed. The 
 oil is transported by a pipeline to the Black Sea, and shipped 
 by tank-vessels. This last method has been adopted by the 
 
PETROLEUM AND COAL. 
 
 295 
 
 American firms for export to Europe. The Rothschilds (with 
 Nobel as engineer) control the RUSSIAN OIL; the Standard 
 Oil Company (Rockefeller) controls the AMERICAN OIL. 
 The two have divided the market of the world between them. 
 
 10. The total PRODUCT OF PETROLEUM is about fifty 
 million barrels a year, of which America produces about 30, 
 Russia about 20 million barrels. Galicia and Roumania pro- 
 duce half a million, Canada a quarter million barrels. Nobel 
 has given millions of dollars to the University of Stockholm; 
 Rockefeller has done the same for the University of Chicago. 
 Thus petroleum will continue to give light. 
 
 11. THE CRUDE PETROLEUM is a limpid to thick liquid, 
 not miscible with water. G 0.79 to 0.94. Wine colored to 
 black. Etherial to offensive odor. 
 
 American petroleum is lighter colored and lighter weight, 
 and gives about twice as much kerosene as the Russian; the 
 latter leaves almost ten times as much of residue, non-vola- 
 tile at 300°. 
 
 12. PETROLEUM IS REFINED by fractional distillation. 
 The fraction passing over between 150 and 300° is kerosene, 
 fit for illuminating purposes. It is further purified by washing 
 with sulphuric acid, then with water, finally with dilute caus- 
 tic soda; lastly re-distilled. American kerosene is nearly 
 colorless, blueish fluorescent; G 0.79 — 0.80, flash-point 
 above 21 degrees. 
 
 73. GAS AND TAR. 
 
 1. THE ILLUMINATION of the streets of cities is peculiar 
 to modern times. The streets of Paris were the first illum- 
 inated (in 1667). Stationary oil lamps or lanterns were used, 
 after attempts to make each householder keep a light burning 
 all night in one window had failed. 
 
296 
 
 LECTURE 73. 
 
 2. When the handling of gases had become familiar 
 towards the close of last century, it was natural to try to dis- 
 tribute by tubes the gas driven off by heat from combustibles 
 for illuminating and heating purposes. Philip LEBON in 
 France, Murdoch and Samuel CLEGG in England perfected 
 plans and appliances. The inventions of the latter continue 
 in use even to-day. 
 
 3. THE STREETS OF LONDON were illuminated by gas in 
 1812; those of Paris in 1815. Now even most small towns 
 are illuminated by gas. IN ENGLAND, ten million tons of coal 
 are used annually for making about three thousand million 
 cubic meters of gas; four hundred million dollars capital • 
 being invested in the six hundred gas works of England. 
 
 Uloc de bouille reprdsentd avec le volume proportionnel Jes priocipaux produits qu’pn en retire. 
 
 1. Bloc de hduille. — 2. Goudron. — 3. Huile Idgdre — 4. Huile lourde. — o.Graisse verte ou huile 4 anthracene. —6. BeBzine. 
 — 7. Toluene. — 8. Phenol. — 9. Naphtaline. — 10. Anthracene. (O'apres les dchantillons de la conference de U. Wurti.) 
 
GAS AND TAR. 
 
 297 
 
 4. THE ILLUMINATING GAS produced represents only 
 about 18 per cent, of the weight of the bituminous coal taken. 
 About 70 per cent, remains as solid residue (coke) in the 
 retort, while about 5 per cent, separates as tar and 7 per cent, 
 as tar water in the condensers between the retort and 
 gasometer. 
 
 o. The gas itself contains many NOXIOUS INGREDIENTS, 
 especially sulphides and cyanides. These are removed by 
 passing the gas over lime and basic iron sulphate. These 
 materials become offensive when dumped; it has been neces- 
 sary to work them up for sulphur and for cyanogen compounds. 
 Thus noxious waste products have been made profitable. 
 
 6. THE COKE left in the retorts is larger in bulk than the 
 coal used; it is a useful fuel, burning (like anthracite) without 
 flame, but containing all the ashes of the coal used. THE 
 TAR and TAR-WATER are run into pits where the two liquids, 
 separate. The most valuable constituent of the tar-water is 
 ammonia; it is converted into sulphate, amounting to about 
 one per cent, of the coal used. 
 
 7. THE COAL TAR PRODUCED in the gas works of the 
 world amounts to over a million tons a year. Germany and 
 the United States produce over one hundred thousand tons 
 each, and England six hundred thousand tons a year. It is 
 worked up mainly for coloring and disinfecting materials. 
 The chemical coal tar industry is most highly developed in 
 Germany. 
 
 8. The crude tar is first subjected to FRACTIONAL DIS- 
 TILLATION. Four fractions are taken at about 170, 230, 270 
 degrees and above, called respectively light oil, middle oil, 
 heavy oil and anthracene oil ; the residual black pitch is drawn 
 as viscid liquid from the boiler. Each of the four tar oils is 
 subjected to further fractioning and chemical purifications. 
 
 9. In this way, the LIGHT OIL yields mainly benzol, 
 toluol and naphta, together with a very small per cent, of 
 
298 
 
 LECTURE 73. 
 
 pyridine. The MIDDLE OIL furnishes mainly phenol and 
 naphtalene. The HEAVY OIL gives naphtols, cresols and 
 liquid paraffins. The ANTHRACENE OIL is the most valuable 
 fraction, giving fast coloring materials (alizarin, 61.10) ; but 
 its amount is small. 
 
 10. The purification and properties of the most important 
 of these TAR PRODUCTS will be considered in another lesson. 
 The graphical representation above given of the amount of 
 these products, compared to the coal taken, is due to Wurtz 
 (1876). The piece of coal (1) represented weighs about 300 
 grammes. Tar, 2. Tar Oils: light, 3; middle and heavy, 4; 
 green, 5. Benzol, 6. Toluol, 7. Phenol, 8. Naphtalene, 9. 
 Anthracene, 10. 
 
 11. QUANTITATIVE EXPERIMENTS on this dry distillation 
 of coal are made by heating one to three decigrammes of coal 
 in a glass tube, connected with a U-tube (submerged in 
 water) and attached to a 100 cc. gas burette. The coke remains 
 in the combustion tube, the tar and ammonia water are found 
 in the U-tube, and 30 to 90 cc. gas collect in the burette. 
 The illuminating gas weighs about half a milligramme per 
 cubic centimeter. Air containing between 5 and 30 per cent, 
 of the gas is explosive; most violently so when containing 
 about 17 per cent. 
 
 12. By heating ten to twenty grammes of bituminous coal 
 in a regular combustion tube, the tar and tar water will show 
 up very nicely, and the gas may be collected in a glass- 
 gasometer or burnt in a gas burner. The burners of the 
 combination furnace nearest the U-tube should, of course, be 
 lit first; the others are turned on gradually to maintain a 
 steady flow of illuminating gas. 
 
74. PHENOL AND ANILINE. 
 
 1. The pure chemical compounds, which, by means of 
 repeated fractioning and washing with appropriate solvents 
 are extracted from coal tar are often called AROMATIC COM- 
 POUNDS. Of these, the most volatile BENZOL, has already 
 been described (62.6). The others of general interest will 
 now be considered. They are strongly acted upon by bromine 
 and by nitric acid. 
 
 2. NAPHTALENE is extracted from the middle tar oil, from 
 which it crystallizes upon cooling; it is purified by sub- 
 limaiion. When pure it, forms colorless lamellar crystals, 
 retaining a peculiar, tar-like odor, and having a notable vapor 
 tension even at 15°. F 79, B 218. Burns with very fuliginous 
 flame. Insoluble in water, soluble in alcohol, ether and ben- 
 zol. Moth balls and tar camphor are commercial forms of 
 naphtalene. 
 
 3. ANTHRACENE is the most valuable constituent of the 
 crude anthracene oil (green oil) coming over above 270°. By 
 hot pressure the more fusible ingredients are removed. The 
 solid residue is redistilled, the fraction passing over between 
 340 and 360 is retained, purified by solution in hot benzol and 
 crystallization on cooling; finally it is sublimated. It forms, 
 colorless, rhomboidal tablets; F 210, B 350. Soluble in hot 
 benzol, difficultly soluble in alcohol and ether, insoluble in 
 water. 
 
 4. Benzol, naphtalene and anthracene are NEUTRAL SUB- 
 STANCES, neither acid nor alkaline, insoluble in water. The 
 tar oils contain a number of allied neutral bodies, differing in 
 properties from the type compounds given. Thus TOLUOL 
 (B 111, still liquid at — 28) remains liquid when benzol 
 crystallizes; it has first been extracted from balsam of tolu. 
 
 5. PHENOL (carbolic or phenic acid) is extracted from the 
 middle tar oil, after the naphtalene has crystallized out. The 
 
300 
 
 LECTURE 74. 
 
 residue is shaken with sulphuric acid to remove alkaline 
 bodies. After this separation, the liquid is stirred with con- 
 centrated caustic soda and heated by steam, forming sodium 
 phenate. From the separated pure solution, sulphuric acid 
 precipitates crude carbolic acid, this being but slightly soluble 
 in water. It is washed, dried over calcium chloride, and 
 rectified. The liquid cooled to — 10° deposits crystals. 
 
 6. Pure phenol forms needle-shaped, colorless crystals. 
 G 2.06; F 42; B 182.5. It has a burning taste, dissolves 
 slowly in 20 parts of water, forming a solution not acting on 
 litmus paper, nor decomposing alkaline carbonates. It is 
 soluble in hot water, alcohol, ether, glycerin, fixed oils, fixed 
 alkalies and ammonia; very caustic on skin (Ka bromide best 
 antidote). It is strongly antiseptic. Ferric chloride colors it 
 violet, even in dilute solution. Bromine water gives a white 
 precipitate. 
 
 7. Associated with phenol are the CRESOLS, which are 
 more liquid (F 6 to over 40 below) and less volatile (B from 
 5 to 15 higher) than phenol. They are more strongly anti- 
 septic than phenol, and thus make crude phenol much more 
 antiseptic than pure phenol ; but also much more poisonous. 
 The most liquid cresol is the strongest in this regard; it is 
 especially abundant in the tar from pine and beech wood. 
 
 8. The heavy tar oil contains two closely related sub- 
 stances distinguished as ALPHA (a) and BETA (/5) NAPHTOL. 
 Both are soluble in hot water, alcohol, ether, and benzol; 
 both are crystallized solids, and smell faintly like phenol. 
 They are distinguished by the following characters. «-Naphtol, 
 most poisonous, silky needles, F 94, B 278, violet with ferric 
 chloride; ./^-Naphtol, not so poisonous (used externally), 
 pearly scales, F 123, B 285, greenish with ferric chloride. 
 
 9. The heavy tar oils contain also minute amounts of three 
 remarkable alkaline bodies, pyridine, chinoline and aniline. 
 They are taken up by the sulphuric acid used in the process 
 of purifying the more abundant substances described. By 
 
PHENOL AND ANILINE. 
 
 301 
 
 super saturation of these acids with lime and distilling, the 
 TAR BASES are obtained. They occur in much larger amount 
 in bone oil, from which they are therefore more generally 
 obtained. 
 
 10. PYRIDINE is a colorless liquid with penetrating, char- 
 acteristic odor, miscible with water; G 0.99 at 0°, B 115. 
 
 When an alcoholic solution of pyridine is treated with a 
 fragment of metallic sodium, the liquid assumes the odor of 
 pepper, and contains the new alkaline liquid called PIPER- 
 IDINE (B 106) forming crystallizable salts with acids. 
 
 11. CHINOLINE is a colorless, strongly refracting liquid of 
 specific, penetrant odor. G 1.095 at 20°, B 239. It forms 
 crystallizable and soluble salts with acids; its bichromate is 
 difficultly soluble, and forms as precipitate in sufficiently con- 
 centrated solutions. Distilling cinchona bark (or its alkaloid) 
 quinine with caustic potassa yields a distillate containing 
 chinoline; hence its name. 
 
 12. ANILINE is a colorless, oily liquid, turning yellow and 
 finally dark brown on exposure to the air. Its odor is weak, 
 but peculiar and unpleasant. G 1.031, B 149, solidified at — 8. 
 Very soluble in water and in alcohol ; precipitates many 
 metals (Zn, Fe, Al) from their aqueous solutions. Chloride 
 of lime colors its aqueous solution violet purple. Chromic 
 acid colors it first red, then violet and finally blue in the 
 presence of strong sulphuric acid. Potassium bichromate gives 
 a dark green color, burning black. Aniline was first (1826) 
 obtained in the dry distillation of indigo (called ANIL in 
 Spanish.) It is the basis of aniline colors. 
 
 75. BONE OIL AND WOOD SPIRITS. 
 
 1. Exposing an organic compound in a retort to a bright 
 red or beginning white heat, while preventing the air from 
 access to the same, drives off all that is volatile. The vapors 
 liquefy in cooled vessels (condensers) and the gases are col- 
 
302 
 
 LECTURE 75. 
 
 lected in gasometers. Such a process is called DRY DISTILLA- 
 TION. The products obtained are four in kind: solid coke, 
 liquid tar and tar water, and the gas mixture. Lecture 73. 
 
 2. Evidently the same material will give DIFFERENT 
 PRODUCTS not only according to the degree of heat used, but 
 even according to the size of the retort and the readiness 
 wherewith the products can escape from the same. The 
 higher the temperature, the further the destruction (decompo- 
 sition) by heat will be carried. In a narrow retort with narrow 
 escape opening, the products will be exposed longer to the 
 decomposing effects of the heat of the retort. 
 
 3. These influences are well understood in the great 
 industry of illuminating gas. To obtain RICH ILLUMINATING 
 GAS, the decomposition must not be carried too far. High 
 temperature, a beginning white heat (1200 to 1400°), and 
 large openings for the escape of the gaseous products give the 
 best illuminating gas. Lower heat gives better tar. In 
 merely coking the coal for Iron furnaces, the coke must be 
 compact; hence the coal is piled high enough to exert pressure. 
 
 4. This process is also very appropriately called DESTRUC- 
 TIVE DISTILLATION. All vegetable and animal substances 
 give the four kinds of products, varying in proportion. Thus 
 animal materials give strongly ammonical tar water, while 
 wood gives acid tar water. To this extent destructive distilla- 
 tion furnishes information concerning the chemical composition 
 of the substance used. 
 
 5. Each of the four products obtained is again VERY COM- 
 PLEX, as has been sufficiently shown in the study of the dry 
 distillation of coal. The composition of the gas, and especially 
 that of the tar, is extraordinarily complex, for a great many 
 chemical substances can be extracted therefrom by appropriate 
 methods. 
 
 6. We cannot give detailed attention to this interesting 
 and difficult analytical process. But in presenting an outline 
 of the dry distillation of WOOD, BONES and SHALES we not 
 
BONE OIL AND WOOD SPIRITS. 
 
 303 
 
 only shall obtain important compounds from these prime ma- 
 terials, but also throw considerable light on the question raised. 
 The products obtained strikingly represent the material used. 
 
 7. BONES are subjected to dry distillation in the manu- 
 facture of Boneblack or animal charcoal (69, 11). The famous 
 DippePs Oil is rich in the alkaline bodies pyridine and chino- 
 line (74, 9-11) to which it mainly owes its medicinal effects. 
 The animal oils of earlier chemists— such as the OIL OF 
 VIPERS, distilled from live vipers — contained the same bases. 
 (Lemery, edition Baron, pp. 669-674; Paris 1757). 
 
 8. WOOD yields upon dry distillation a strongly acid dis- 
 tillate. Much of the acetic acid of the market is obtained by 
 this process. The highest amount of acid is obtained at low 
 temperature, not exceeding 400°. The charcoal left in this 
 case is brownish, its temperature of ignition is correspondingly 
 low. Beech wood yields, per hundred, about 25 charcoal, 5 
 tar, 45 crude wood vinegar and 25 of gas. The tar from 
 beech wood is specially rich in CREOSOT, the meat preserva- 
 tive of smoke. Creosot concentrated and purified is called 
 guajacol (G 1.12, B 201). Bituminous SHALES give largely 
 paraffins and the so called solar-oil. 
 
 9. the principal constituents of the tar water from 
 wood are pyroligneous or acetic acid (B 118), wood spirits 
 (B 66) and aceton (B 56). Saturating with milk of lime pre- 
 cipitates the acid as calcium acetate, from which the liquid is 
 distilled off. Redistilling with chloride of lime converts the 
 acetone into chloroform (B 61), which passes over first; the 
 almost pure wood spirits (methyl alcohol) is collected above 66°. 
 
 10. Distilling the CALCIUM ACETATE with concentrated 
 muriatic acid gives ACETIC ACID, which is purified by distil- 
 lation with potassium bichromate in silver retorts. The use of 
 sulphuric:: instead of muriatic acid is objectionable, since gypsum 
 precipitates, and organic substances present reduce the 
 sulphuric to sulphurous acid, which distills over with the acetic 
 acid from which it is difficultly removed. 
 
304 
 
 LECTURE 70. 
 
 11. ACETIC ACID, in its most concentrated form (glacial), 
 solidifies at 17 ; B 118. G 1.08 at 0°. It has a characteristic, 
 suffocating odor, and a strong acid taste; it is very corrosive. 
 It dissolves many metals, forms salts (acetates) which are 
 almost all soluble. It is the oldest acid known. 
 
 Forming by oxidation of alcohol, its lead and copper salts 
 were made in antiquity by covering the metals with the residue 
 drawn from the wine press. 71, 8. 
 
 12. Methyl alcohol is a colorless, limpid liquid of a 
 pleasant ethereal odor. G 0.81, F — 134, B 66.5. Miscible 
 with water, alcohol and ether, and as solvent generally as 
 effective as alcohol. 
 
 ACETONE is a colorless liquid of ethereal odor, G 0.81, 
 B 56, soluble in water, alcohol and ether. With sodium 
 bisulphite it forms a crystalline compound. 
 
 CHLOROFORM is a colorless liquid of pleasant, character- 
 istic odor, hardly soluble in water, miscible with alcohol and 
 ether, G 1.48, F — 70, B 61. We shall soon study these 
 substances more in detail. 
 
 76. STARCH, SUGAR AND GLUCOSE. 
 
 1. The principal prime materials of the organic world have 
 now been considered. It has also been shown how DEFINITE 
 CHEMICAL COMPOUNDS have been extracted from these — 
 many thereof having been in use since antiquity. It will next 
 be necessary to consider some of the CHEMICAL CHANGES 
 of these leading organic compounds. 
 
 2. The sweet principle of the cane (sucrose) and of the 
 grape (glucose) we considered in the first lesson (58) of our 
 organic chemistry; the most important cellular substance, 
 starch, was considered later on (66). We shall now show 
 how both starch and sucrose are readily CONVERTED INTO 
 GLUCOSE by simple chemical means. 
 
STARCH, SUGAR AND GLUCOSE. 
 
 305 
 
 3. Starch, thoroughly wet by rubbing with a little water, 
 then boiled with much water, gives starch paste (66, 10) ; 
 when cold, this gives the delicate iodine reaction (blue). But 
 if a little dilute sulphuric acid be added to the boiling starch 
 paste, this will gradually get thin. If the boiling is stopped 
 while the liquid still is sticky, it gives a precipitate with 
 alcohol, but no blue with iodine. The starch has been con- 
 verted into DEXTRINE. 
 
 4. If the boiling continues, the starch solution will finally 
 cease to be sticky, and give no longer a precipitate with 
 alcohol. If the acid is now neutralized (say by adding a 
 slight excess of powdered chalk), the solution will give the 
 glucose reaction (58, 6). Accordingly the STARCH HAS BEEN 
 CONVERTED INTO GLUCOSE. Dilute muriatic acid (1 per 
 cent.) effects the conversion more completely. 
 
 5. The roots of most composite (Inula helenium. Dahlia, 
 Helianthus, Taraxacum, etc.) contain a pseudo-crystalline sub- 
 stance, soluble in water, precipitable by alcohol, tinted yellow 
 by iodine, called INULIN, and considered to take the place of 
 starch. It rather seems to correspond to amidine (66.10) 
 and may, therefore, be called levulin; for boiled with dilute 
 acids it yields a glucose, deporting itself chemically exactly 
 as the glucose made from true starch. 
 
 6. Physically the glucose from starch and from inulin act 
 in almost opposite manner on polarized light. The solution 
 fulled into a brass tube (10 or 20 cm. long), closed with plane 
 plate glass at the ends, turns the plane of polarization of light 
 to the RIGHT in the case of glucose from starch, to the LEFT 
 in case of glucose from inulin. These two forms of glucose, 
 accordingly, are called DEXTROSE and LEVULOSE. 
 
 7. HONEY contains both kinds of glucose, namely, dextrose 
 and levulose. By stirring up honey in cold alcohol, only the 
 levulose is dissolved ; the dextrose is separated by filtration 
 and pressure, and can be dissolved in boiling alcohol, from 
 which it will crystallize upon cooling. 
 
306 
 
 LECTURE 76. 
 
 8. Sucrose dissolved in water, very slowly changes into a 
 mixture of levulose and dextrose, called INVERT-SUGAR. By 
 heating, the process is accelerated. It is quite prompt when 
 sucrose is boiled with dilute acid; the boiled solution, after 
 neutralization, will exhibit the glucose reaction with Fehling’s 
 solution. Sugar boiled with fruit (acid juice) is also inverted; 
 hence in putting up fruit, sucrose ought to be added last. 
 
 9. Sucrose solutions do not ferment; syrups keep quite 
 well. But all forms of GLUCOSE FERMENT promptly. Hence 
 starch sugar is made on a commercial scale (from potato starch 
 in Germany, from corn starch in the United States) and some 
 finds its way to breweries, acetic acid works, and even to 
 other factories. 
 
 10. Claude Bernard (p. 36) discovered (1856) animal 
 starch (GLYCOGEN) in the liver, and in oysters. The latter 
 may be crushed in a mortar, and thrown into boiling water; if 
 to the cold, opaline filtrate, a large amount of alcohol (or 
 glacial acetic acid) is added, the glucogen separates as a 
 white, amorphous powder. It is changed into glucose (dex- 
 trose) exactly as is starch. 
 
 11. All farinaceous food consists largely of starch, which 
 can only enter the blood in soluble form, as glucose. The 
 liver evidently takes a prominent part in effecting this change. 
 In a normal state (health) this glucose is used in the system 
 (assimilated). In DIABETES MELLITUS, large amounts of glu- 
 cose are drained from the system in the kidneys. The urine be- 
 comes exceedingly abundant in volume, high in specific gravity 
 (1.035) and gives the glucose reaction with Fehling’s solution. 
 
 12. Cellulose, by protracted boiling with dilute acids, can 
 also be converted into glucose (SUGAR OF RAGS) ; more 
 rapidly if the acid is stronger, when much material is lost^ by 
 charing. Fusing cellulose with caustic potash, or boiling 
 sugar, glucose or starch with rather strong nitric acid, yields 
 OXALIC ACID (63, 10) as the common oxidation product. 
 From the nitric acid it separates on cooling in crystal form. 
 
STARCH, SUGAR AND GLUCOSE. 
 
 307 
 
 Notes. — Gum Arakic is an exudation from species of acacia and 
 mimosa in northern Africa and the Orient. It is colorless, soluble in 
 water, insoluble in alcohol, like dextrine, which latter is accordingly 
 often called British Gum. In that case dextrine has commonly been 
 manufactured by moistening a ton of starch with 300 kgr. of water, to 
 which 2 kgr. of common nitric acid had been added. The mass, after 
 being air dried, is heated, in thin layers, to 100 ; in about an hour or 
 two it has changed to dextrine. 
 
 Gum Arabic solution, boiled with dilute acid, yields a glucose 
 (arabinose), precisely as does dextrine. 
 
 Mucilage is extracted by boiling water from linseeds and other 
 materials. Mucilages resemble gums. 
 
 Pectine dissolves in hot water and gelatinizes on cooling. It is pre- 
 cipitated by absolute alcohol from certain fruit juices (black currants, 
 etc.), after having removed lime by oxalic acid and albuminoid sub- 
 stances bv tannin. 
 
 77. ALCOHOL AND ETHERS. 
 
 1 . The extraction of alcohol from wines has been shown 
 (58, 11), and its industrial production mentioned (58, 12). 
 We have also seen how dilute alcohol is converted into an acid 
 (71, 8) and how this acetic acid is industrially obtained 
 (75, 11) in concentrated form. Dilute acetic acid, obtained 
 from alcoholic liquids, is called VINEGAR, and is used in the 
 preparation of food and at table; it retains the flavor of its 
 origin. 
 
 2. If to a little water in a test tube is added at least an 
 equal volume of concentrated sulphuric acid, the mixture will 
 be quite hot. If now a few drops of alcohol be added, the 
 pleasant odor of ETHER will be noticed. If a crystal of any 
 acetate be dropped into this liquid, the more fragrant odor of 
 ACETIC ETHER will be recognized. Compare 55.12. Such 
 effects have already been observed by the alchemists; Lully 
 in the 13th, Valentin in the 15th century. 
 
 3. This simple test shows how common and compound 
 ethers are obtained, namely by distilling alcohol with much 
 
308 
 
 LECTURE 77. 
 
 sulphuric acid alone and with some organic or other acid. 
 The ether, being very volatile QUITE INFLAMMABLE, and 
 forming explosive mixtures with air, this distillation must 
 be made with great care, and by experienced operators only. 
 In ether factories, all heating is done by steam carried from 
 another building, so that no fire nor flame is allowed in the 
 building where ethers are made. 
 
 4. To obtain COMMON ETHER (so-called sulphuric ether) 
 200 gr. of sulphuric acid are mixed with 120 gr. alcohol, and 
 the mixture distilled at 140 to 145 degrees. By a special con- 
 trivance, a continuous, though small flow of alcohol, correspond- 
 ing to the ether distilled over, may be kept up till the acid 
 becomes inert when too dilute from water formed in the 
 process. The receiver must be well cooled. — The ether formed 
 contains no sulphuric acid. 
 
 5. The CRUDE ETHER so obtained is treated with milk of 
 lime for a day, and frequently agitated therewith; this 
 removes the acid that has passed over. The ether is next 
 washed with water, dried on calcium chloride, and finally 
 rectified over metallic sodium on the water bath, if the last 
 traces of water and alcohol are to be removed. 
 
 6. Pure ether is a very limpid, colorless liquid of a 
 strong, characteristic and pleasant odor, and a sharp, burning 
 taste. G 0.75 at 0, B 34.5; it solidifies to crystalline scales 
 at — 31. It is non-miscible with water, on which it floats. It 
 mixes with alcohol in all proportions. Water dissolves, upon 
 shaking, about one-tenth its own volume of ether. Ether is 
 a most important solvent (S, P, lo) especially for fats and oils. 
 Very combustible and inflammable, see above (3). 
 
 7. By distilling a mixture of (fused) sodium acetate, alcohol 
 and sulphuric acid in the proportions of 10, 6, 15, crude 
 ACETIC ETHER is obtained. It is purified by shaking with 
 milk of lime and rectification from calcium chloride. G 0.91 
 at 0, B 74; water dissolves one-seventh its own volume ; mixes 
 with alcohol in any proportion. It is a solvent of resins and 
 
ALCOHOL AND ETHERS. 
 
 300 
 
 gun cotton. Wine and wine vinegar contain a sufficient 
 amount of this ether to be recognized by the very character- 
 istic odor, 
 
 8. When acetic ether is treated with sodium hydrate, 
 alcohol reappears, and can be distilled off; the solid residue 
 is sodium acetate. Thus the original substances are repro- 
 duced; the REACTION HAS BEEN REVERSED. Consequently 
 alcohol must be a hydrate of some radical, passing into the 
 ether by mere double decomposition. Liebig (p. 23) called 
 this radical ETHYL, symbol Et. 
 
 9. The reactions involved are all DOUBLE DECOMPOSI- 
 TIONS. In the formation, Na Ac^te and Et H^te (alcohol) give 
 the volatile Et Ac^te (acetic ether) and Na H^te in presence of 
 excess of heated strong sulphuric acid, which forms Na 
 and absorbs H H^te (water). When the acetic ether is treated 
 with Na Hate at common temperatures, alcohol (Et Hate) and 
 Na Acate reform; the first can be distilled off, the latter 
 remains as salt. 
 
 The formation of common ether now is readily understood. 
 Alcohol, as ethyl hydrate, Et OH, in contact with the hot, 
 concentrated, hygroscopic sulphuric acid, gives off water and 
 becomes ether or ethyl oxide, Et 2 O. Two alcohol give one 
 each of water and ether, namely 2 Et OH give Ha O and 
 Et2 O. 
 
 10. Many other ethers are distilled in a like manner from 
 alcohol and the salt in presence of an excess of strong sul- 
 phuric acid. Thus common salt (Na CL^e) yields CHLORIC 
 ETHER. Heating chloric ether with water in a covered vessel 
 under moderate pressure gives alcohol and muriatic acid. 
 This double decomposition again shows that alcohol is ethyl 
 hydrate. 
 
 11. When, however, strong muriatic acid (H Cf^^) and 
 alcohol (Et Hate) are heated in an AUTOCLAVE (28, 3-4) up 
 to 140°, or under a pressure of 40 atmospheres, chloric ether 
 (Et ClUe) and water (H Hate) are formed by double decom- 
 
310 
 
 LECTURE 78. 
 
 position. This reversible reaction again confirms the consti- 
 tution of alcohol as ethyl hydrate. Under 40 atmospheres the 
 reaction is the reverse of that under one or two atmospheres. 
 The ether Et Chde^ boils at 11 degrees. It is sold in strong, 
 sealed glass tubes and used as a local anesthetic. 
 
 12. Taking potassium nitrite — and better strong muriatic, 
 instead of sulphuric acid — NITROUS ETHER is obtained, 
 which as 5% solution in alcohol is a valuable remedy, called 
 sweet spirits of nitre. Also this reaction is reversed; for 
 potassium hydrate added to the nitrous ether gives again 
 potassium nitrite and alcohol. Thus the ethyl radical forms 
 alcohol with H^te, and ethers with acid radicals. Nitrous 
 ether boils at 17°. 
 
 78. FATS AND SOAPS. 
 
 1. Oil and water do not mix. By shaking, temporary 
 emulsion may be obtained, which soon separates again in the 
 two layers of water and oil. But if an alkali is dissolved in 
 the water, and the mixture gently heated, complete solution 
 is affected; a SOAP is produced. This solution of a fat in an 
 alkaline aqueous liquid is called SAPONIFICATION. 
 
 2. Wood ashes used instead of caustic alkali effect an 
 incomplete solution only. The Gauls, according to Pliny, 
 operated in this manner. In modern times the cheapening of 
 the process has made soap available to everybody. England 
 produced in 1791 twenty thousand tons of soap, worth eight 
 million dollars; ninety years later, it produced eight times as 
 much, costing only a little more than twice as much (eighteen 
 million dollars). Industrial progress had brought the price 
 down to one -fourth. 
 
 3. Alkalies are not the only substances that make oil dis- 
 solve in water on moderate heating. Litharge has a corres- 
 
FATS AND SOAPS. 
 
 ;ui 
 
 ponding effect; the product, called PLASTER, differs from 
 ordinary soaps. The great chemist, Scheele (p. 169), repeat- 
 ing this process in his little pharmacy in Sweden, discovered 
 1779 the “sweet principle of oils,” which we now call 
 GLYCERIN, in the aqueous liquid remaining when the plaster 
 is finished. 
 
 4. Chevreul (p. 37) completed the PROXIMATE CHEMI- 
 CAL ANALYSIS OF THE FATS as early as 1815, mainly by a 
 chemical examination of the old process of saponification. Fie 
 first separated the natural fats into simple fats (59.9) such as 
 olein, stearin. Fie next found that each simple fat, in saponi- 
 fication, really undergoes a double decomposition with the 
 caustic alkali (hydrate). Consequently, FATS ARE SALTS 
 (OR ETHERS). Glycerin is the common base of all fats. 
 
 5. Thus, stearin is glyceryl stearate, if the radical of 
 glycerin be denoted according to Liebig’s system (yl). With 
 caustic potassa (potassium hydrate) on boiling, double decompo- 
 sition takes place. Soap is formed, that is potassium stearate 
 (soft soap). Glycerin, accordingly, must be GLYCERYL 
 HYDRATE. If salt is thrown into this soap solution, sodium 
 stearate (hard soap) separates, being much less soluble than 
 soft soap. 
 
 6. Chevreul dissolved four parts of fat in two parts of 
 water containing one part of caustic potassa. The solution 
 was effected on the water bath. When complete, he dilutes 
 with water and adds just enough tartaric acid to neutralize the 
 potassa; THE FATTY ACID, being insoluble in water, sepa- 
 rates on cooling, forming an oily layer or a solid cake. By 
 washing with water this acid is purified. 
 
 7. THE REACTION involved is again merely a double 
 decomposition. Soap from stearine by caustic potassa is 
 potassiurn stearate. Adding to its aqueous solution hydrogen 
 tartrate gives potassium tartrate (difficultly soluble) and 
 hydrogen stearate or stearic acid, insoluble in water. On the 
 hot solution this acid forms an oily layer, which solidifies to 
 
312 
 
 LECTURE 78. 
 
 a fatty cake on cooling. Palmitic acid appears in the same 
 form. Oleic and butyric acids are liquid at common tempera- 
 tures. The last is volatile and can be distilled off. 
 
 8. These fatty acids are soluble in alcohol and ether, 
 from which they crystallize below their melting point. This 
 is, for stearic acid 69, palmitic acid 62, oleic acid 14. Butyric 
 acid solidifies below the freezing point and boils at 163. The 
 other fatty acids named, when heated, decompose before 
 boiling. With steam they volatilize, like many volatile oils 
 (60, 3). The so-called stearin candles consist mainly of 
 stearic acid and not of stearin. 
 
 9. It is evident that a mixture of fatty acids can be more 
 readily separated than the corresponding mixture of the fats. 
 Accordingly, saponification is generally resorted to in THE 
 ANALYSIS OF FATS. Butyric acid is distilled off. Oleic 
 acid decanted and pressed from the solids. The amount of 
 potassa (in mgr. per gramme of fat) required for saponification 
 (Koettstorfer’s number) is determined by difference. The 
 amount distilled off is determined by tenth -normal alkali; the 
 number of cc required for 5 grammes of fat is called Reichert’s 
 number. It is most important in testing butter. 
 
 10. The soap and stearine candle industries have flourished 
 especially in France, where the principal chemical investiga- 
 tions of the fats have been made. The soap industry at Mar- 
 seilles is the most extended and oldest in the world; it is the 
 commercial center of the olive oil region. Genuine castile 
 soap is made from this oil. France excells also in toilet soaps, 
 on account of the perfumes required (60, 5-7). 
 
 11. The DIRECT DECOMPOSITION OF FATS into acid and 
 glycerine is effected by high pressure steam (10 atmospheres) . 
 After several hours’ action, the glycerin is dissolved in the 
 water while the fatty acids, floating on the surface, are blown 
 over with the steam. The glycerin so obtained is the purest 
 in the market. This process is largely employed in England 
 and in the United States. 
 
FATS AND SOAPS. 
 
 313 
 
 12. The direct SYNTHESIS OF FATS from their constituents, 
 acid and glycerin, has been effected (in ISoT) by Berthelot 
 (p. 27). It takes place at common temperatures to a very 
 slight extent in a very long time. It is quite slow even at 
 100 degrees. In the autoclave, at 200 degrees (or about 16 
 atmospheres) Berthelot effected the synthesis in a few hours, 
 in three distinct stages, (proving that glycerin is a tri -valent 
 base 43, 11). Here we have witnessed another most remark- 
 able reversible reaction. 
 
 79. NITROGLYCERIN AND GUN-COTTON. 
 
 1. Man alone has not been endowed with special ORGANS 
 OF DEFENSE, nor is he swift enough to escape. But intelli- 
 gence has armed his hand, and courage needs no wings to 
 flee. Thus primitive man conquered the animal world in the 
 golden age, with stone and bow, with ax and spear. 
 
 2. In his contests for dominion, man depended for ages on 
 the strength of his own MUSCLE. The armies of the Romans, 
 and of the Saracen and Christian Knights during the Crusades, 
 exhibit this phase of man in its highest form. When cunning 
 and over- confidence decide the contest, as at Troy, we feel 
 sympathy neither for the victor nor for the vanquished. 
 
 3. About equally remote in time, the contest between 
 David and Goliath foreshadows the contrast between modern 
 and ancient arms. Reading the dramatic account in the Scrip- 
 tures (I Samuel 17) one is fascinated by the parallel. Goliath, 
 proud of his muscle ; David, frail youth, conquers by MECHANI- 
 CAL SKILL, long before the arm of the giant can reach him. 
 
 4. THE EXPLOSIVES, furnished by chemistry, have en- 
 dowed the modern soldier with a power incomparably greater 
 than his own muscular strength. The introduction of the 
 crude black powder changed the condition of man ; serfdom 
 was doomed when the blunderbuss took the place of the spear. 
 
314 
 
 LECTURE 79. 
 
 During the half century now closing, CHEMISTRY HAS AGAIN 
 GREATLY ENLARGED THE RANGE AND POWER OF THE 
 INDIVIDUAL; we may hope it will lift the burden of militaiism 
 from the race. 
 
 5. In BLACK POWDER or gun-powder, we have a MIXTURE 
 of two combustible substances (C and S) with a sufficiency 
 of nitre to furnish the oxygen to completely burn them (21, 12). 
 A spark is sufficient to start the combustion. This suddenly 
 converts the small amount of solid powder into a very large 
 volume of hot gas. The pressure thus produced is about two 
 thousand atmospheres. The projectile is thrown, or the rock 
 Is broken by the force of such an explosion. 
 
 6. The modern chemical explosives (nitroglycerin, gun- 
 cotton, smokeless powder) are not explosive mixtures, but 
 essentially EXPLOSIVE COMPOUNDS. The combustible 
 materials (C, H) are in atomic proximity to the oxygen of the 
 compound. The action is therefore instantaneous, so much so 
 that the air acts like a resistant solid. A drop of nitro- 
 glycerin, exploding on a hard steel plate, knocks a hole into 
 the same— the air acting like the sand tamping in a blast hole 
 charged with black powder. 
 
 7. The work of the last fifty years has therefore been 
 mainly directed to find means to TEMPER THE VIOLENCE of 
 these modern explosives. Schoenbein, in Germany, dis- 
 covered gun-cotton (1846), Sobrero, of Turin (1847) nitro- 
 glycerin. Ncbel, of Sweden, tempered the later in dynamite 
 (1867), which ever since has done man’s work in mine, quarry 
 and tunnel. Turpin and Vieille, of France, in 1888 made the 
 first practical smokeless powder. The three steps taken are 
 about twenty years apart in time. 
 
 8. NITROGLYCERIN is made by pouring glycerin into a 
 cold mixture of concentrated nitric (3) and sulphuric acid (5 parts 
 per unit of glycerin). The nitroglycerin (G 1.60), floating on 
 the cooled, acid mixture, is separated and washed with water 
 and soda solution. It is sweetish. Being extremely explosive, 
 
NITROGLYCERIN AND GUN-COTTON. 
 
 315 
 
 it is not accepted for transportation in most countries. By a 
 blow or concussion it explodes instantaneously; small amounts 
 burn quietly in an open vessel. Its products of combustion 
 are carbon dioxide, water, nitrogen and a slight excess of 
 oxygen. 
 
 9. Nitroglycerin is an ether, corresponding to the original 
 fat itself; namely GLYCERYL NITRATE. For when treated 
 with caustic potassa it yields, by double decomposition, potas- 
 sium nitrate and glyceryl hydrate or glycerin. The sulphuric 
 acid simply takes up the water in the process. Nitroglycerin 
 is absorbed by infusorial earth in the proportion of three to one. 
 The mixture called DYNAMITE, feels dry, is reasonably safe, 
 accepted for transportation under proper restrictions, and has 
 for a quarter of a century been the most effective industrial 
 explosive. 
 
 10. Cotton soaked in the same acid mixture is converted 
 into GUN-COTTON. If the mixture is less concentrated, 
 PYROXYLIN results. The first contains about 14 per cent, of 
 nitrogen, the latter only 11. A solution of ferrous sulphate 
 in concentrated muriatic acid decomposes either with evolution 
 of nitric oxide gas; the volume of which, determined by the 
 gas burette, gives the per cent, of nitrogen introduced. 
 Pyroxylin is soluble in a mixture of alcohol and ether; the 
 solution, on spontaneous evaporation, .leaves a film of collodion. 
 Gun-cotton is not soluble. 
 
 11. While not soluble in any solvent, true gun-cotton 
 gelatinizes with acetic ether and with acetone, especially upon 
 the addition of a little camphor. SMOKELESS POWDER is 
 mainly such gelatinized gun-cotton and pyroxylin, of about 13 
 per cent, nitrogen. It is rolled into plates, cut into small 
 squares, which are lightly covered with graphite. Giving no 
 solid product, its explosion gives no smoke, only a light cloud 
 of watery vapor. 
 
 12. To explode either black or smokeless powder, MER- 
 'CURIC FULMINATE caps are used. It is made by adding 
 
316 
 
 LECTURE 80. 
 
 alcohol to a solution of mercuric nitrate. The process is very 
 dangerous, therefore the particulars need not be given. 
 
 With cannon hurling a ton weight ten miles, rapid firing 
 guns able to kill a hundred men a minute, and torpedoes that 
 will blow up a five-million-dollar iron clad in an instant, we 
 may hope that attack will soon be useless. 
 
 80. CHLORACETIC ACID AND CHLORAL. 
 
 1. In the four preceding lessons a number of chemical' 
 changes of organic compounds have been presented. In no 
 case have we noticed any chemical reaction other than those 
 common to inorganic chemistry (see Lecture 28). Thus far, 
 most processes involved a DOUBLE DECOMPOSITION. It 
 will be advisable to select also a few striking instances of 
 substitution. 
 
 2. As far back as 1815, Gay-Lussac noticed that wax, 
 bleached with chlorine gas, absorbed some thereof without 
 change of volume in the gas. Faraday, in 1824, and Liebig 
 and Bunsen, in 1832 discovered similar cases of SUBSTITU- 
 TION OF CHLORINE FOR HYDROGEN in organic compounds. 
 Soon after (1834) Dumas made this a subject of transcendent 
 chemical importance. 
 
 3. In 1840, Dumas changed acetic acid into TRI -CHLORA- 
 CETIC ACID by simple substitution. Large, dry, glass 
 stoppered flasks were filled with dry chlorine gas. A small 
 amount of glacial acetic acid was introduced into each; only 9 
 decigrammes per liter. Exposed to bright sunshine, the walls 
 of these flasks soon were covered with small, colorless, crystals 
 of (tri- )chloracetic acid. 
 
 4. In this process there is NO CHANGE IN VOLUME of 
 the gas, neither increase nor diminution. Accordingly, hydro- 
 gen and chlorine replace one another in equal measures, or 
 
CHLORACETIC ACID AND CHLORAL. 
 
 317 
 
 equivalent for equivalent. Therefore MH, the organic com- 
 pound, and Cl Cl, the gas (40, 10) give M Cl and H Cl, 
 the latter equal in volume to the chlorine gas taken. In a 
 certain sense, this substitution may be considered a double 
 decomposition. 
 
 5. Finally, quantitative determinations show that every 
 equivalent of acetic acid (GO mgr.) has taken up three equiva- 
 lents of chlorine gas (3G cc). Hence the substituted acid is 
 called TRl-chloracetic acid. It crystallizes in rhombohedrae, 
 rather deliquescent. G 1.42, F 46, B 195. Forms salts 
 isomorphous with the corresponding acetates. 
 
 6. A given weight of purified crystals of chloracetic acid, 
 when saturated by normal potassium hydrate, shows the 
 equivalent to be 163.5. This furnishes the simplest demon- 
 stration that it is tri-chloracetic acid. For the SATURATING 
 EQUIVALENT of acetic acid is 60. Substituting three chlorine 
 (106.5) for 3 hydrogen (3) will increase the weight of the 
 equivalent 103.5, making it 163.5, as easily confirmed by 
 experiment. 
 
 7. The solution of potassium chloracetate, gently heated 
 with an excess of potassium hydrate, yields CHLOROFORM 
 (75, 12), readily recognized by its odor. This shows that the 
 essential part of chloroform is a constituent of trichloracetic 
 acid. When sodium amalgan is added to the acid or to its 
 salts, the nascent hydrogen produced reduces the acid to the 
 initial state, acetic acid. 
 
 8. The production, by Dumas, of this remarkable acid, 
 exerted a most decisive influence on the development of 
 organic chemistry during the last half century. The general 
 law of ORGANIC SUBSTITUTION was now admitted to be, 
 EQUIVALENT FOR EQUIVALENT. 
 
 9. When absolute alcohol is saturated at the freezing point 
 with chlorine gas, ALDEHYDE is formed. The name was 
 coined by Liebig on the American OmniBUS principle, to indi- 
 
318 
 
 LECTURE 80. 
 
 cate that the new substance is ALcohol DEHYDrogenatus. 
 The same product is obtained by a moderated oxidation of 
 common alcohol, say with potassium bichromate and sulphuric 
 acid. The purified aldehyde is a limpid liquid, of suffocating 
 odor, G 0.80, B 21, soluble in water, alcohol and ether. It 
 reduces silver from ammoniated silver nitrate on gently warm- 
 ing the solution (mirror). 
 
 10. If absolute alcohol is fully saturated with dry chlorine 
 gas — the temperature being properly regulated — CHLORAL is 
 formed. It is purified by distillation, first from sulphuric acid, 
 thereafter from quicklime. It is a colorless, oily liquid. G 
 1.54, F — 75 (solidifies), B 98. Soluble in water and alcohol. 
 When treated with nascent hydrogen (from zinc and sulphuric 
 acid) it is reduced to aldehyde. Chloral reduces silver solu- 
 tion like aldehyde. Both form a crystalline precipitate with 
 sodium bisulphite. 
 
 11. With water, chloral combines to CHLORAL HYDRATE 
 which forms fine colorless crystals. F 46, B 97. Hence 
 chloral is generally employed as hydrate. It is a most valu- 
 able hypnotic. When treated with potassium hydrate, chloro- 
 form is produced. Since blood is alkaline, chloral probably is 
 gradually converted into chloroform in the system (Liebreich) . 
 Heated with nitric acid, chloral and its hydrate, yield tri- 
 chloracetic acid, which is most readily produced by this 
 method. 
 
 12. The reactions given prove conclusively that alcohol, 
 aldehyde, chloral, trichloracetic acid and acetic acid are VERY 
 CLOSELY RELATED mutually and to chlorform; for we have 
 transformed most of these bodies into one or more of the 
 others, and obtained chloroform from several of them. To 
 enter more fully into the mechanism of these changes, we 
 must now begin the study of their chemical composition. 
 
81. PROXIMATE AND ULTIMATE 
 ANALYSIS. 
 
 1. The materials furnished by nature we have found to be 
 essentially COMPLEX. The rocks are all complex, most 
 minerals contain admixtures of others — to us, impurities — and 
 only in the finest, crystallized specimens do we find a true 
 chemical individual, a single chemical compound. Organic 
 materials are every way more complex than even the rocks. 
 
 2. To determine the real CHEMICAL COMPOUND ACTU- 
 ALLY PRESENT in a given mineral or rock is often quite 
 difficult, and not unfrequently impossible. We can always 
 ascertain what elements are present, but in many cases it is 
 impossible to state how they are combined, or what proximate 
 compounds are contained in the sample. Thus it is even 
 impossible to state exactly what salts are contained in a 
 given mineral water, though it is conventionally done with a 
 sublime disregard of knowledge. 
 
 3. To determine the proximate CONSTITUENTS OF 
 ORGANIC MATERIALS is not less difficult. The substances 
 themselves, being so readily changed by even contact with 
 neutral solvents, greatly adds to the difficulties. However, by 
 care and skill, the principal classes of organic compounds can 
 be separated. The methods used for this purpose have been 
 exemplified in the preceding lectures. 
 
 4. Chemists have endeavored to bring this work into a 
 system. Thus Dragendorff has suggested an order of pro- 
 cedure for PLANT ANALYSIS. Ether removes fats, and alcohol 
 resins, without changing starch, gum and proteid substances; 
 hence they conveniently precede water and aqueous solvents. 
 But no one system is applicable in all cases. 
 
 5. A careful review of the METHODS ACTUALLY 
 EMPLOYED in our preceding lectures will be more beneficial 
 than a lengthy exposition of any special system of procedure. 
 
320 
 
 LECTURE 81. 
 
 We will merely add that these extractions either have for 
 their object the determination of the amount of a certain con- 
 stituent or the preparation thereof for further research. In 
 the first case, the substance used is limited, and must be most 
 completely exhausted by freely using reagents and time ; in the 
 latter case, both the material and the reagents are used freely, 
 to secure the purest product obtainable. 
 
 6. Such methods give us knowledge of the proximate con- 
 stituents of organic substances. They are methods of PROXI- 
 MATE ANALYSIS. Thus we determine the amount of nicotine 
 in tobacco, the percentage of morphine in opium, of sucrose in 
 the cane, of glucose in the grape, of starch in the grain, of 
 albumen in the egg. The results should not be stated with a 
 precision that is fictitious. Chemists should not pretend to 
 have done what is impossible. The thousandth of a per cent, 
 is sheer humbug. 
 
 7. When an organic compound has been produced in the 
 pure state, it may be subjected to ULTIMATE OR ELEMENTARY 
 ANALYSIS as the first step in the search of its chemical com- 
 position and structure, expressible by appropriate chemical 
 formulm. It is evidently an utter waste of time to attempt the 
 establishment of a chemical formula for anything not itself a 
 true chemical compound. 
 
 8. Lavoisier showed that the four elements C, H, N, O 
 constitute the bulk of all organic materials; they have even 
 been termed ORGANOGENS. In a very large number of com- 
 pounds, nitrogen does not occur; they consist of C, H, O only. 
 On these facts the common method of ULTIMATE ANALYSIS 
 BY COMBUSTION was planned by Lavoisier, improved by 
 Gay-Lussac, and practically perfected by Liebig. 
 
 9. The organic compound — pure and dry — is mixed with a 
 large excess of purest copper oxide (Gay-Lussac), The mix- 
 ture, heated in a combustion tube, produces H 2 O from H, 
 CO 2 from C, and N as gas, the organic substance burning at 
 the expense of the oxygen of the copper oxide. The water 
 .and carbon dioxide produced are collected and weighed as 
 
PROXIMATE AND ULTIMATE ANALYSIS. 
 
 321 
 
 shown previously (32, 6) ; the volume of nitrogen gas produced 
 is measured. The important PRACTICAL DETAILS of such 
 combustion must be studied in the laboratory. 
 
 For educational purposes and elementary LABORATORY 
 PRACTICE, small and short combustion tubes can be used 
 over four wing gas burners in a row, the tube protected with 
 a sheet of brass or iron. If no N, only the U-tube and gas 
 burette with air lock for CO 2 is required; if N present, insert 
 potassa bulb and use gas burette for N. 
 
 10. The total amount of CARBON in the organic substance 
 taken is yV of the increase of the potassa bulb (CO 2 ); the 
 amount of HYDROGEN is y of the increase of the U-tube 
 (H 2 O) ; compare 31, 7 and 5. The weight of the NITROGEN 
 is li mgr. per cc under common conditions (49, 8). The 
 OXYGEN in the compound cannot be determined directly 
 (55, 12; 53, 12) ; it is determined by difference. 
 
 11. Dividing the weights so obtained for C, H, N (and O) 
 by the weight of the substance used, gives the amount of each 
 element PER UNIT OF WEIGHT. Moving the decimal point 
 two places to the right, gives the PERCENTAGE of each. 
 This is all that quantitive chemical analysis can do. It is well 
 to repeat the combustion with different amounts of substance. 
 The percentage found should reasonably well agree, independ- 
 ent of the absolute amount taken. 41, 12. 
 
 12. The following table gives the analytical results (in per 
 •cent.) for a few TYPICAL COMPOUNDS to which we shall 
 
 frequently refer: 
 
 Carbon. 
 
 Hydrogen. 
 
 Oxygen. 
 
 1. Benzol, 
 
 . 92.3 
 
 7.7 
 
 
 .2. Alcohol, 
 
 . 52.2 
 
 13.0 
 
 34.8 
 
 3 . Ether, 
 
 . 64.8 
 
 13.6 
 
 21.6 
 
 4. Acetic Ether, .... 
 
 . 54.4 
 
 9.1 
 
 36.5 
 
 ■5. Acetic Acid, 
 
 . 40.0 
 
 6.7 
 
 53.3 
 
 6. Tartaric Acid, .... 
 
 . 32.0 
 
 4.0 
 
 64.0 
 
 7. Sucrose, 
 
 . 42.1 
 
 6.4 
 
 51.5 
 
 S. Urea (N 46. 7) 
 
 . 20.0 
 
 6.6 
 
 26.7 
 
82. EMPIRICAL AND MOLECULAR 
 FORMUL/E. 
 
 1. Several of the eight typical organic compounds for 
 which the results of their elementary analysis are given in the 
 preceding table we have found to sustain remarkably CLOSE 
 CHEMICAL RELATIONS to one another (Lecture 80). This 
 applies particularly to the four alcoholic compounds (Nos. 2 to 
 5). Yet the percentage composition fails to give the slightest 
 indication of such relationship. 
 
 2. But suppose we express this per cent, composition by 
 the chemical symbols C, H, O, N. The value of these is, 
 respectively 12, 1, 16, 14 (40, 7). That is, let us weigh the 
 carbon by weights of 12 units, oxygen by weights of 16 units; 
 that is, by atomic weights. To do this, we evidently need 
 only to DIVIDE THE PERCENTAGE BY THE ATOMIC WEIGHT. 
 
 3. The following table gives the results of this calcula- 
 tion, and also the simplest RATIOS of these quotients: 
 
 
 Compounds. 
 
 c 
 
 — Quotient. - 
 H 
 
 o 
 
 c 
 
 ■ Ratios. ■ 
 H 
 
 o 
 
 1. 
 
 Benzol, 
 
 7.69 
 
 7.7 
 
 
 1 
 
 1 
 
 
 2. 
 
 Alcohol, 
 
 4.35 
 
 13.0 
 
 2.17 
 
 2 
 
 6 
 
 1 
 
 3. 
 
 Ether, 
 
 5.40 
 
 13.6 
 
 1.35 
 
 4 
 
 10 
 
 1 
 
 4. 
 
 Acetic Ether, 
 
 5.53 
 
 9.1 
 
 2.28 
 
 2 
 
 4 
 
 1 
 
 5. 
 
 Acetic Acid, 
 
 3.33 
 
 6.7 
 
 3.34 
 
 1 
 
 2 
 
 1 
 
 6. 
 
 Tartaric Acid, 
 
 2.66 
 
 4.0 
 
 4.00 
 
 2 
 
 3 
 
 3 
 
 7. 
 
 Sucrose, 
 
 3.51 
 
 6.4 
 
 3.22 
 
 12 
 
 22 
 
 11 
 
 8. 
 
 Urea, 
 
 1.66 
 
 6.6 
 
 1.67 
 
 1 
 
 4 
 
 1 
 
 
 With N 3.34 
 
 
 
 
 2 
 
 
 
 4. The simple ratios are in all cases evident, except for 
 SUCROSE. For this substance we see that the ratio H:0 
 evidently is 2:1. That of C:0 is nearly 36:33 or 12:11, 
 which being tried by division with 12 and 11 gives in both 
 cases the quotient 0.29. Hence the ratios are as given. For 
 
EMPIRICAL AND MOLECULAR FORMUL/E. 
 
 323 
 
 UREA, the only nitrogenous compound in the list, the value 
 for this element is separately stated. 
 
 5. These ratios are all simple numbers; accordingly organic 
 compounds conform to DALTON’S LAW of fixed, simple 
 multiple proportions (40, Note). They represent the number 
 of times each atomic weight must be taken to express the 
 results of elementary analysis of the compound. Thus two 
 C, six H and one O represents exactly the per cent, of carbon, 
 hydrogen and oxygen found in alcohol by elementary analysis. 
 
 6. Accordingly C2H6O is a chemical formula represent- 
 ing the quantitative composition of alcohol. In the same way 
 C4H10O represents the results of the elementary analysis 
 of ether, and CH4N2O the composition of urea. These 
 chemical formulas are called EMPIRICAL FORMULA, be- 
 cause they express the mere fact determined by the elemen- 
 tary analysis of the substance. 
 
 7. Comparing the four alcoholic compounds, we see that 
 these empirical formulas already mark a CLOSE KlNSFllP 
 between them. They all have one oxygen only. Acetic 
 ether has exactly double the amount of both carbon and hydro- 
 gen found in acetic acid. In alcohol the proportion of hydrogen 
 is increased to |. In ether we find exactly the sum of alcohol 
 and acetic ether. All for equal amounts of oxygen. 
 
 8. For volatile substances it is easy to determine their 
 MOLECULAR WEIGHT (40, 10 to 12). Applying the method 
 given to the volatile substances in our list, we find the follow- 
 ing results: Benzol, 78; Alcohol, 46; Ether, 74; Acetic 
 Ether, 88; Acetic Acid, 60. Summing up the atomic weights 
 of the empirical formula, we find it equal to the molecular 
 weights for alcohol and ether; half the amount for acetic ether 
 and acetic acid; one-sixth the amount for benzol. 
 
 9. THE MOLECULAR FORMULA OF A COMPOUND REP- 
 RESENTS ONE MOLECULE OF THE SUBSTANCE- that is, 
 the number of milligrammes of the substance which, in the 
 gaseous state, occupies as much space as two milligrammes of 
 
324 
 
 LECTURE 82. 
 
 hydrogen under the same temperature and pressure (40, 10). 
 Accordingly, the molecular formulae are: Benzol Ce He, Alco- 
 hol C2 He O, Ether C4 H^o O, Acetic Ether C4 Hg O2, Acetic 
 Acid C2 H4 O2. 
 
 10. The last three substances on our list are non-volatile; 
 they decompose before they volatilize. The above method 
 accordingly is inapplicable. Saturation of the acid by normal 
 alkali would only give the equivalent, but not necessarily the 
 molecule. COMBINATION WITH THE MONOVALENT SILVER 
 is frequently sufficient. Thus when silver acetate is ignited, 
 it leaves 0.645 silver per unit. Since Ag = 108, it follows 
 that silver acetate is 166.8. Hence Acetate 58.8 and H Acetate 
 59.8 which is close to the true 60. In this manner we find 
 tartaric is C4 He Oe. 
 
 11. A method, due to RAOULT, based upon the DEPRES- 
 SION OF THE MELTING POINT, is now quite generally used 
 for non-volatile substances. It requires a very sensitive ther- 
 mometer. We cannot here enter upon the experimental or 
 theoretical detailSi The method excellently supplements the 
 data needed for non-volatile solids. It is found that the 
 molecular formulas of sucrose and of urea are identical with 
 their empirical formulae. 
 
 12. UREA, CH4N2O is extracted from fresh urine. 
 Evaporate to one -tenth its volume. Add excess of strong 
 nitric acid: Urea nitrate appears in tabular, six-sided crystals. 
 Separate, dissolve (purify by animal charcoal) saturate with 
 barium hydrate solution (giving Ba N^^®). Evaporate to dry- 
 ness, extract with alcohol, which dissolves the Urea. Crys- 
 tallize. It forms colorless (white) quadratic prisms, very 
 soluble in water, less so in alcohol. F 132. Waste nitro- 
 genous materials leave the body in the form of urea, about 30 
 grammes a day. 
 
83. RADICAL AND STRUCTURAL 
 FORMUL/E. 
 
 1. The molecular formulas present more of the CHEMICAL 
 RELATIONS than the empirical formulae. Thus, the formula 
 of alcohol and acetic acid give a sum exceeding that of acetic 
 ether by H2 O; in fact, this ether is formed from the two 
 compounds with separation of water. Again, doubling the 
 formula of alcohol gives that of ether and of H2 O, agreeing 
 with the preparation of common ether. Compare 77. 
 
 2. In order more clearly to exhibit the chemical relations 
 or reactions of the compounds, the symbols of the molecular 
 formula should be grouped in a manner to represent the CON- 
 STITUENT RADICALS of the compound. Thus, since alcohol, 
 C2H6O, is chemically a hydrate, it must contain the 
 monovalent negative radical OH. That leaves C2H5 which, 
 accordingly, must represent its positive radical ethyl. See 77, 8. 
 
 3. Consequently, the molecular formula C2 He O of alco- 
 hol should be written C2 H5. OH, to represent the radicals 
 or proximate constituents of the compound, known to be 
 present according to the chemical reactions of the substance. 
 Such formulas are called RADICAL FORMULA. 
 
 4. It is customary to connect the formulas of the radicals 
 by DOTS OR DASHES^-as many as the valence of the same. 
 Since OH is monovalent, ethyl must also be monovalent; 
 accordingly a single dot has been inserted between OH and 
 C2 H5. It will be readily understood that the divalent O must 
 be marked next to the ethyl. Compare Lecture 40 and 43. 
 
 5. In ACETIC ACID, C2 H4 O2, one hydrogen is replace- 
 able by monovalent metals (Na, Ag) ; hence it stands as 
 positive against the balance as a negative, C2 H3 O2. H. 
 This shows the formation of acetic ether C2 H5. O2 H3 C2 
 from alcohol C2 H5 OH and acetic acid C2 H3 O2.H by 
 
326 
 
 LECTURE 83 . 
 
 double decomposition with separation of water H. OH or 
 H Hate. Xhe reason for writing O2 next to C2 H5 is evident 
 from what has been shown above. 
 
 6. We must next inquire into the constitution of the mono- 
 valent electro positive radical C2 H5 and the monovalent 
 electro negative radical C2 H3 O2. The tri-chloracetic acid 
 of Dumas ( 80 , 3 ) and the production of chloroform therefrom 
 ( 80 , 7 ) will enable us to unravel the STRUCTURE OF THE 
 negative RADICAL C2 H3 O2— and thereby that of the posi- 
 tive C2 H5. 
 
 7 . By chlorination of acetic acid it is necessarily the H3 in 
 the radical that are replaced by chlorine, and not the fourth, 
 positive hydrogen ; for the chloracetic acid saturates metals 
 exactly as does acetic acid itself, or contains that same posi- 
 tive, replaceable hydrogen atom. Accordingly, TRICHLOR- 
 ACETIC ACID contains the monovalent negative radical 
 C2 CI3 O2. 
 
 8. When treated with an alkali, say Ka OH, trichloracetic 
 acid yields chloroform. Analysis shows CHLOROFORM to 
 consist of carbon, hydrogen and chlorine; its empirical formula 
 is CH CI3. Its molecular weight is found to be nearly 120 . 
 Consequently, its molecular formula is CH Cl 3. Hence the 
 above radical must contain the monovalent radical C CI3. 
 Accordingly it is C CI3. C O2. 
 
 9. If trichloracetic acid is neutralized with sodium hydrate 
 and the chloroform distilled off, the residue, after proper con- 
 centration, will yield rhombic tablets. Identically the same 
 crystals are obtained by saturating the aqueous distillate from 
 red ants (Formica rufa) with sodium hydrate. The crystals 
 accordingly are sodium FORMATE. 
 
 10 . From these crystals, FORMIC ACID is obtained pure 
 by distillation with an acid. Analysis gives the empirical 
 formula CH2 O2. The molecular weight is found to be 46 . 
 It has but one H replaceable by Na. Consequently, its radi- 
 
RADICAL AND STRUCTURAL FORMULAE. 
 
 327 
 
 cal formula is CH O2. H. When heated with concentrated 
 sulphuric acid it yields carbonic oxide gas, CO, and water 
 H. O H. Hence it is H. CO. OH, for the radical CARBONYL 
 C O is divalent. 
 
 11. The negative radical C2 CI3 O2 of trichloracetic 
 acid has thus been found to contain the monovalent C CI3 
 and CO. O — . Its RADICAL STRUCTURE is therefore 
 C CI3.CO. O — where the last dash represents the monovalent 
 character. Hence sodium trichloracetate is CCl3.CO.ONa. 
 Acetic acid accordingly is CH3.CO.OH, the last H being 
 replaceable by metals. 
 
 12 . But alcohol C2 H5. OH is convertible into acetic acid 
 by oxidation. Consequently, the radical ethyl C2H5 contains 
 the link CH3 as terminal; it is therefore CH3.CH2 — . 
 Hence the STRUCTURE OF ALCOHOL is CH3.CH2.OH. 
 In this manner the radical structural formulas of compounds 
 are determined from their chemical reactions. The results 
 of such determinations for five of our tabulated compounds are 
 here appended. 
 
 2 . 
 
 3 . 
 
 4 . 
 
 5 . 
 8 . 
 
 Name. Radical Formulm. 
 
 Alcohol, . C2 Hs OH 
 Ether, . . (C2H5)2 0 
 
 Acetic Ether, C2H5.O2H3C2 
 Acetic Acid, C2 H3 O2. H 
 Urea, . . CO (NH2)2 
 
 structural Formulm. 
 CH3. CH2. OH 
 CH3.CH2.O.CH2 CH3 
 CH3.CH2.O.CO.CH3 
 H. O. CO.CH3 
 H2N. CO. NH2 
 
 84. POLYMERIC AND ISOMERIC 
 COMPOUNDS. 
 
 1. At the close of the first quarter of this century the outer 
 walls of organic chemistry were constructed by FOUR MASTER 
 BUILDERS on the foundation laid by Lavoisier, Gay-Lussac 
 and Chevreul. Faraday in England, Dumas in France, Liebig 
 in Germany and Berzelius in Sweden. In his Annual Reports 
 
328 
 
 LECTURE 84. 
 
 (begun 1821), the latter critically reviewed the work of the 
 younger men'. 
 
 2. . Liebig had enjoyed the advantages of the French school 
 at Gay-Lussac’s. He had studied the FULMINATES there 
 (79, 12) . The empirical formula of the terrible explosive silver 
 fulminate he found (1823) to be Ag C N O. But the same 
 formula had been given by Wohler for the non-explosive silver 
 CYANATE, a year previously. Liebig, thinking that possibly an 
 
 WOHLER. 
 
 error had been committed, repeated all analyses, but again 
 obtained the same results. Hence two entirely different bodies 
 are represented by the same empirical formula! 
 
 3. A few years later (1828), Wohler, working on potas- 
 sium cyanate, Ka O Cy, found that by heating a mixture of 
 equivalent solutions of this salt and of ammonium sulphate, 
 Am 2 O 4 S, the dry residue, upon extraction with alcohol, gave 
 CRYSTALS OF UREA. (72, 12) . Double decomposition yielded 
 
POLYMERIC AND ISOMERIC COMPOUNDS. 
 
 329 
 
 difficultly soluble Ka the other compound, Am O Cy 
 
 had evidently changed into Urea. 
 
 4. Writing out the radicals Am and Cy, the ammonium 
 cyanate is represented by the formula NH4 O. CN, while urea 
 (83, 12) is represented by H 2 N. OC. NH2. Evidently, the 
 hydrogen has changed place, and carbon and oxygen have 
 combined more intimately, nitrogen and carbon less so, the 
 nitrogen now being partly saturated by the additional hydrogen. 
 This has been called a synthesis of urea; but it is simply an 
 “atom WANDERUNG.” 
 
 5. About the same time (1825) Faraday discovered the 
 liquid hydrocarbon BENZOL (62, 6) in coal tar. On analysis 
 he found C H as the empirical formula. He was amazed at 
 this result, because the same formula was considered to rep- 
 resent the gas called olefiant gas, obtained by gently heating 
 the mixture of one volume of alcohol and six volumes of con- 
 centrated sulphuric acid. 
 
 6. Berzelius for several years supposed these results to be 
 erroneous. But while investigating TARTARIC ACID and tar- 
 trates (1831), he discovered that RACEMIC ACID had exactly 
 the same quantative composition as tartaric acid, the analyses 
 of both leading to exactly the same empirical formula. Now he 
 admitted the facts stated and coined the names still in use: 
 polymeric and isomeric compounds. 
 
 7. In the terms of the present, different substances, having 
 the same percent composition, and therefore expressed by the 
 same empirical formula, are either POLYMERIC or ISOMERIC, 
 according as their molecular formula is different or identic. 
 In the latter case, the radical formulae differ. 
 
 8. The empirical formula of olefiant gas now is known to 
 differ from that of benzol; it is CH2 and not CH. But 
 ACETYLENE (which Berthelot obtained by direct synthesis, 
 forty years ago, and which now is produced in quantity by 
 Moissan from his calcium carbide and water) has identically 
 the same percentage composition as benzol, and therefore the 
 same empirical formula CH. 
 
330 
 
 LECTURE 84 . 
 
 9. The molecular weight of benzol is 78 (82, 8), but that 
 of acetylene is found to be 26 only. Accordingly, while the 
 molecular formula of benzol is CeHe (82, 9), acetylene is rep- 
 resented by the molecular formula C2H2. — It thus appears 
 that a benzol molecule weighs three times as much as a mole- 
 cule of acetylene. Berthelot has indeed, CONDENSED 
 ACETYLENE TO BENZOL by passing it through a red hot 
 tube. He has also decomposed benzol into acetylene. 
 
 10. The empirical formula Ag C N O represents both silver 
 cyanate Ag. O. CN and silver fulminate AggrCib where a 
 stands for O2N and bforCN. These compounds are isomeric. 
 The radical formulae for ammonium cyanate and for urea have 
 been given in 4; these compounds are isomerics, represented 
 by their common empirical formula CH4 N2 O. The case of 
 tartaric and racemic acids is of a higher order, and will be con- 
 sidered in the next lecture. 
 
 11. Since the masters brought the nature of isomerism and 
 and polymerism to light, these phenomena have been found to 
 be common among organic compounds. Thus the molecular 
 formula of ETHER, C4H10O represents quite a number of 
 different isomerics. Among the most common of these is 
 BUTYL ALCOHOL, C4H9.OH or CH3 .CH2 .CH2.CH2 .OH. 
 It is a liquid (obtainable from butyric acid) of pleasant odor, 
 requiring 12 volumes of water for solution. G 0.81 (at 20), 
 B 117. Nobody could possibly confound such a liquid with 
 ether; yet it has not only the same empirical, but even the 
 same molecular formula. 
 
 12. In view of these facts, it is manifest, that the empirical, 
 and even the molecular formula of compounds, are of com- 
 paratively little value.; they really give no insight into the 
 chemical nature of the same, for they each one apply to many 
 entirely different isomeric or polymeric compounds that often 
 could not be confounded by the merest tyro. THE CHEMICAL 
 NATURE OF COMPOUNDS IS EXPRESSED IN THEIR RADICAL 
 AND STRUCTURAL FORMULA. 
 
85. RIGHT- AND LEFT-HANDED 
 COMPOUNDS. 
 
 1. Further study of isomerics has revealed the existence 
 of compounds containing exactly the same chemical radicals 
 and yet so different, one from the other, that not only man, 
 but even monads readily can distinguish them. The case of 
 tartaric and racemic acid of Berzelius is the first instance of 
 this kind. 84, 6. 
 
 2. Recent researches have shown that these compounds 
 differ one from the other as does the glove of the right-hand 
 from that of the left. Though both hands are identical in 
 most respects, they are not equal, but symmetric — the one is 
 exactly like the reflected image of the other. Chemical com- 
 pounds of this kind are designated as LEFT- (1) and RIGHT 
 (d, dextro) -HANDED modifications or geometrical isomerics. 
 
 3. These differences are by no means hard to recognize. 
 When crystallized, the substances show it to the unaided eye. 
 When in solution, they show it so plainly in POLARIZED 
 LIGHT that one of the most common methods of analysis of 
 organic compounds is based upon this difference (45, 6). 
 Common officers of the civil government determine import 
 duty and credit bonus on sugar by this method of polarization. 
 Even monads will eat the one and refuse the other of these 
 isomerics. 
 
 4. THE HISTORY of this line of research is both fascinat- 
 ing and instructive. If we could give a lecture course on this 
 subject instead of a single lecture, we would have ample 
 material to sustain the interest ’till the close. The researches 
 leading to these wonderful results also sharply mark the 
 difference between routine work of detail and the discoveries 
 due to genius. The masses never can do the work of the 
 master. 
 
332 
 
 LECTURE 85. 
 
 5. The now popular method of SPECIAL RESEARCH im- 
 ported, duty free, with cheap parchments, is as impotent as 
 the empty formula of Bacon and the hairsplitting verbiage of 
 the scholast. On the contrary, we see the work of physicist 
 (Biot) astronomer (Arago, Sir John Herschel) crystallographer 
 (Hauy, Mitscherlich) and chemist (Berzelius, Pasteur) con- 
 centrated in the one final result under consideration. 
 
 6. To approach this subject understandingly, we must, for 
 the moment, leave our ethers and acids with the chemists and 
 examine once again the quartz crystal with the physicist and 
 crystallographer. ARAGO had discovered (1811) that it turns 
 the plane of polarized light, passing parallel to its axis. BlOT 
 had found that this rotation is exactly proportional to the 
 thickness of the plate, and that many organic compounds 
 (sugars, volatile oils, alkaloids) possess the same property. 
 
 7. The most important forms of the crystals of quartz are 
 represented on the upper part of p. 65. The dominant prism 
 r and rhombohedr^e P and z have been described (10, 6). 
 Close inspection had already shown HAUY the rhombic facets s 
 and the (plagihedral) trapez facets x in the zone- like belt P s 
 X r (fig. 5) . The angles are Ps 151.1, r x 168.0 and s r 142.0. 
 The rhombic facets generally show a high luster, and may be 
 striated parallel to edge Pr (figs. 6, 7). The facets x are 
 usually dim. 
 
 8. The astronomer SIR JOHN HERSCHEL, in 1820, dis- 
 covered that in right-handed quartz (upper P s x r to right, 
 fig. 7) the polarized ray of light is turned to the right, while 
 in left-handed quartz (P s x r to left, fig. 6) the light is turned 
 in the opposite direction. We now use plates of such crystals 
 in finer polarizing microscopes. The order of succession of the 
 colors on turning the analyzer indicates the nature of the 
 crystal, whether right- or left-handed. 
 
 9. Solutions of tartaric acid show polarization while solu- 
 tions of the isomeric racemic acid show none. But PASTEUR 
 (1848) found that ammonium-sodium racemate gave on 
 
RIGHT- AND LEFT-HANDED COMPOUNDS. 
 
 333 
 
 crystallization, crystals showing similar plagihedral facets, 
 either to the right or to the left of certain main forms, precisely 
 as we find it in quartz. Picking these crystals by hand, 
 separating the acids by Scheele’s method (63.2) and dissolv- 
 ing these separately, he obtained from the non -active racemic 
 acid both a right-handed and a left-handed acid. The first is 
 identical with tartaric acid. 
 
 10. Accordingly, RACEMIC ACID is merely a combination 
 of r (old) and 1 (new) tartaric acid. Pasteur demonstrated 
 this conclusion by synthesis, which took place with notable 
 evolution of heat. The compound resulting was racemic acid. 
 The molecular formula of tartaric acid C 4 H 6 O 6 indicates none 
 of these relations. It is dibasic, containing twice CO. OH. 
 Radically it is HO.CO.CHX.CHX.CO.OH where X stands 
 for hydroxyl OH. Non -active isomerics are marked i 
 (inactive). Doubled (neutral), meso. 
 
 11 . Now all the formulas of organic compounds given show 
 plainly that carbon may be considered quadrivalent; compare 
 also 40, 4, 5. Remembering this, the formula just quoted 
 shows tartaric acid to contain two carbon atoms each combined 
 mutually and with the monovalent H, OH marked X and 
 CO. OH, the weights of which are 1, 17,45. The fourth 
 valence holds exactly half the entire compound, or 75. 
 
 12 . In other words, each one of the central carbons is com- 
 
 bined or loaded with the weights 1, 17, 45, 75, all four unequal. 
 The load is entirely unsymmetric. A carbon atom so combined 
 is called ASYMMETRIC by VAN’T HOFF (Holland, 1874) and 
 LE BEL (France, 1874), who independently generalized this 
 condition: No rotary polarization without at least one 
 
 asymmetric carbon atom. 
 
 Pasteur before Biot. The research here reported was the first one 
 made by Pasteur, submitted to the Academy of Sciences of Paris. 
 The old investigator of rotary polarization, Biot, was to report on the 
 merit of the work of young Pasteur. The following is a synopsis of the 
 
334 
 
 LECTURE 85. 
 
 account of the examination made by Biot, as reported by Pasteur him- 
 self in his Lecture on January 2oth^ 1860, before the Chemical Society 
 of Paris: 
 
 Biot requested me to call or. him and to repeat my experiments in 
 his presence. He gave me racemic acid^ which he had himself optically 
 examined, and found to be entirely inactive. I converted this in his 
 presence, into the Ammonio-Sodium salt, using the ammonia and soda 
 furnished by himself (Biot). The solution was set aside in his labora- 
 tory tor spontaneous evaporation. When 30 to 40 grammes of crystals 
 had separated, he again requested me to call at the College de France, 
 in order to pick out, under his very eye, the right- and left-handed 
 crystals. He asked me to repeat the declaration, that the crystals which 
 I should place to his right would, in solution, turn the polarized light to 
 the right, and those which I should place to his left would deflect the ray 
 to the left. After I had done the work accordingly, he said that he 
 would himself do the rest. He carefully prepared the solutions from 
 weighed quantities, and when he was ready to make the flnal observation 
 by means of the polarizing apparatus, he called me again into his room. 
 He first put the most important solution into the apparatus, namely the 
 solution which was to deflect to the left. Without taking a reading, at 
 the mere aspect of the tints of color in the two-halves of the field (of 
 the Soleil Saccharimeter) he instantly recognized the presence of a 
 deflection to the left. The gray-haired man was profoundly moved; he 
 grasped my hand and said : Wy dear boy, I have loved science all my 
 life so much that I hear my heart beat for joy at this sight.” 
 
 We may, with Pasteur, call attention to the fact that Biot had, for 
 twenty years, urged chemists to study rotary polarization as a means of 
 investigating the structure of chemical compounds. Pasteur was the 
 first who did so and was richly rewarded. Strange as it may seem, this 
 very research led him directly to his wonderful biological discoveries 
 which now dominate medicine (71. ii). For searching for methods of 
 separation of these right- and left-handed substances, which deport 
 themselves alike to all chemical reagents, he naturally tried the action 
 of ferments. Now tartrates were known to ferment readily. Accord- 
 ingly he added this ferment to a solution of ammonium racemate, to 
 which the necessary albumin had been added as ferment-food (71. 4). 
 The liquid was placed in the tube of his polarizing apparatus. Race- 
 mate being inactive, no deflection was seen at the beginning. But as the 
 fermentation spread, the plane of polarized light turned towards the left. 
 The ferments (from right-handed tartrates) consumed this right-handed 
 tartrate of the ammonium racemate. The left-handed portion was not 
 attacked — and caused the turning of the plane of polarized light. 
 
 The ox eats no flesh and the lion refuses to eat grass. To the ferment 
 cells of right-handed tartrates, the left-handed isomeric evidently 
 appears as different as do flesh and grass to the higher animals. 
 
86. TETRAHEDRON AND BENZOL RING. 
 
 1 . Modern scientists frequently deride the views of the 
 philosophers of Ancient Greece on the co,nstitution of things. 
 The use of the regular polyhedrae by Plato (Tim^os) is a 
 favorite topic of this kind. Nevertheless, the chemical litera- 
 ture of to-day places PLATO’S TETRAHEDRON at the head of 
 the science. It has become the nucleus of all organic com- 
 pounds. It is CH 4 . 
 
 2. When Van’t Hoff and Le Bel had recognized the asym- 
 metric carbon, they both concluded that the four hydrogen 
 atoms of CH 4 occupy the corners and the carbon atoms the 
 center of a regular tetrahedron. In series; these TETRA- 
 HEDRAE WERE STRUNG along a line, corner to corner, inde- 
 pendent of the fundamental laws of mechanics. 
 
 3. THE PUZZLE of placing three hundred soldiers on the 
 ramparts of a square fort so that each side shall be defended 
 by one hundred men is commonly solved by placing fifty in the 
 middle of each side and twenty-five at each corner. Such 
 solutions answer the purpose of a puzzle admirable till the 
 enemy attacks all sides at once. As reward for this puzzle - 
 solution, Van’t Hoff was called from Holland to the chair of 
 chemistry in the University of Berlin, Germany. 
 
 4. It is only after almost fifteen years that the mechanical 
 absurdity of this stringing of tetrahedrae was recognized. The 
 utter absence of scientific understanding in the highest circles 
 of German chemistry is strikingly evidenced by the report in 
 Bischoff’s Big Book (1894) on Stereochemistry; 1060 pages 
 only. He simply prints (p. 79) both pictures; the one marked 
 “jetzt” and the other marked “fruher.” No comments. 
 “ALLES WURST.” 
 
 5. If the “latter view” of Van’t Hoff is taken, the alcoholic 
 compounds necessarily have a CORKSCREW STRUCTURE. 
 This structure of alcoholic compounds would seem to be emi- 
 
336 
 
 LECTURE 86. 
 
 nently appropriate to those who know alcohols numbers two 
 and five only. Really, the theory demands no serious consider- 
 ation here. See my paper, Comptes Rendus, T. 113, p. 745; 
 1891. 
 
 6. Ostwald (1896) in his History of Electro-Chemistry 
 (only 1,152 pages, mostly reprints) repeatedly castigates 
 German scientists of a preceding period for succombing to the 
 disease “ Naturphilosophie.” In a near future, the chemists 
 of the present age will probably be said to have succombed to 
 the TETRAHEDRAL BACILLUS. 
 
 7. There is another, and considerably older picture in mod- 
 ern chemical literature. It is the HEXAGON, introduced by 
 Kekule (1866) to represent the constitution of BENZOL, 
 CeHe. The six carbons are supposed to form a hexagon and 
 to be tied alternately singly and doubly, and outwardly com- 
 bined with one hydrogen each. Thus the four valencies of 
 each carbon are supposed to be saturated. See diagram. 
 
 8. This view has rendered undoubted services to the 
 progress of chemical science. It has been frequently attacked, 
 also on thermochemical grounds by Thomsen, of Copenhagen. 
 Prismatic and other more elaborate formulae, have been pre- 
 sented as substitutes. The solution of Kekule appears to 
 represent all facts known. That IT IS IN ACCORDANCE 
 WITH MOLECELAR MECHANICS we have shown in our 
 Principles of Chemistry, 1874, and in the Comptes Rendus, 
 1875. 
 
 9. The relations between BENZOL AND ACETYLENE, 
 discovered by Berthelot (84, 9) are strong facts in favor of 
 this ring-form. The formula resolves itself in the same three 
 parts, held by a double tie. Each of these parts represents 
 one of acetylene. This indicates also that the carbon atoms 
 really do not form a regular hexagon, but correspond in position 
 to the rhombohedron. 
 
 10. NAPHTALENE (74, 2) is a condensed form of benzol; 
 two atoms united under loss of two carbons. The accepted 
 
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 -ail. f T ^ 
 
 oA^o 
 
 20iCu.S^°iKo.puMK. 
 
 fr/u,. 
 
 & JStI}' 
 
 * 
 
 ‘ SoJ^ 
 
 S.L iK-.h, 5 
 
 :y-k^ 
 
 22'-^^ 
 
 2,r2 
 
 (^. 
 
 I <57i 0^0* 
 
 / O* . I . o 
 
 Ci fcri'c Aci^.^* 
 
 SoL.clcjW, 
 
 "Pia.fl4- T. 
 J2j;ijj|UTV_J^ 
 
 Bl-ACKBOAftD SIA&aAMS 
 

 y' ■ 
 
 
 -y?.. 
 
TETRAHEDRON AND BENZOL RING. 
 
 337 
 
 •constitution is shown in the diagram given. The two carbons 
 common to the two benzol rings are tied doubly; hence only 
 four carbons in each ring can unite with hydrogen. The 
 formula for naphtalene must be CioHg. 
 
 11 . The trivalent nitrogen may take the place of one carbon 
 in either benzol or naphtalene. Being trivalent it cannot com- 
 bine with an outer hydrogen, so that these compounds contain 
 respectively 5 and 7 hydrogen only. C 5 N H 5 is called PYRI- 
 DINE (74, 10) and C 9 N H 7 is CHINOLINE (74, 11). See 
 diagrams given. 
 
 12. Many higher condensations exist. Thus ANTHRA- 
 CENE (74, 3) is considered to result from two complete ben- 
 zol rings tied rather curiously by 2 CH as shown in the dia- 
 gram. The structure looks like three benzol rings, the middle 
 of which has a diagonal tie. Formula C 14 Hio- These forms 
 are the only ones that require attention. 
 
 87. ALCOHOLIC COMPOUNDS. 
 
 1 . The general chemical principles exposed in the preced- 
 ing lectures were obtained in the study of the compounds 
 ■extracted from the most common organic prime materials. We 
 will now take a look at the principal CLASSES OF COM- 
 POUNDS. A detailed systematic exposition of organic com- 
 pounds must be looked up in any of the numerous manuals. 
 
 2. All organic compounds may be roughly arranged in 
 THREE GREAT DIVISIONS. Aromatic compounds contain 
 the benzol ring. Alcoholic compounds do not contain such a 
 ring. Complex compounds may contain both alcoholic and 
 aromatic radicals. 
 
 3. Of true alcoholic compounds, the acids have always 
 been most prominent. Scheele and Chevreul opened the way 
 in this investigation. We have seen that all these acids con- 
 
338 
 
 LECTURE 87. 
 
 tain the radical carboxyl CO united to hydroxyl OH. That 
 is, acids contain the TERMINAL — CO. OH or summarily 
 CO H. The dash indicates that this terminal is mono- 
 valent. 
 
 4. In formic, acetic, butyric, palmitic and stearic acids we 
 find this acid-terminal only once; these acids are called mono- 
 basic. In oxalic and tartaric acids, this terminal occurs twice; 
 they are said to be dibasic. In tribasic citric acid this termi- 
 nal occurs three times. These are about the only alcoholic 
 acids specially studied in the preceding. The NUMBER of 
 times this terminal occurs in any acid determines the SATU- 
 RATING CAPACITY of that acid. 
 
 5. If we determine the formulas of the radicals united with 
 this terminal in the first five acids enumerated, we find them 
 to be H, CHg, C3H7, Ci5 H3,, C17 H35. For any number 
 m of carbon atoms, these monovalent alcohol radicals are seen 
 to contain twice that number of hydrogen atoms and one over 
 (2 m + 1). The ALCOHOLIC RADICAL Rm is therefore 
 expressed by the general formula Cm H^m+i. 
 
 6. Oxalic acid is that terminal united with itself or 
 HO. CO— CO. OH. The formula of tartaric acid has already 
 been given (85, 10). CITRIC ACID (63, 5) contains the acid 
 terminal — CO. OH three times, being united to each carbon 
 of the trivalent alcohol radical CH 2 . CH. CH 2 . Formulae of 
 this kind become rather complex when written out in full, and 
 are especially difficult for the printer. Hence we only have 
 given the radicals, separately. 
 
 7. It is much preferable to REPRESENT COMPLEX 
 FORMULAE GRAPHICALLY. To avoid too great speciali- 
 zation we represent the atoms by circles or disks. The tetra- 
 valent carbon by a large, black, the divalent oxygen by a 
 smaller open circle, and the monovalent hydrogen by a dot. 
 The trivalent nitrogen we represent by a triangle. If ties 
 are to be marked, they may be represented by straight lines 
 as usual. 
 
ALCOHOLIC COMPOUNDS. 
 
 3:i9 
 
 8 . THE DIAGRAM and fully written out formula of citric 
 acid will once for all show the advantages of this representa- 
 tion of organic compounds (see plate). We wish to insist 
 that these diagrams are merely to be taken as graphic formulas 
 which it is much easier to write and to read than the complex, 
 fully written out DEVELOPED FORMULA of the books that 
 are the despair of the compositor and the student. 
 
 9. By strong reducing agents — such as nascent hydrogen 
 produced by sodium amalgam in the open, or hydriotic acid in 
 the autoclave— THE ACIDS CAN GENERALLY BE REDUCED 
 TO AN ALCOHOL. In that case, the carbonyl CO is reduced 
 to CH2. Thus acetic acid CH3.CO.OH yields common 
 (ethyl) alcohol CHg. CH2. OH. This process is quite general 
 and reversible. Alcohols, by oxydizing agents, are converted 
 into acids (77, 1). 
 
 10. ETHERS ARE EITHER OXIDES OR SALTS. The first 
 may be compared to water H2 O or H.O.H in which the 
 hydrogen is supposed to be replaced by two monovalent 
 alcohol radicals. These are the same in simple, different in 
 mixed ethers. Examples Et. O. Et and Et. O. Me, where Me 
 represents methyl CH3. The ether salts contain an acid 
 radical and an alcohol radical. Example, acetic ether, Et. O. Ac 
 where Ac stands for acetyl. CH3.CO — . 
 
 11. AMINES AND AMIDES may be compared to ammonia 
 NH 3 exactly as ethers to water. In amines, the hydrogen of 
 ammonia may be supposed to have been replaced by alcohol 
 radicals; in the amides we have one or more acid radicals.. 
 Thus ethyl amine Et N H 2 and acetyl amide Ac N H 2 (Ace- 
 tamide). The latter is a crystalline solid, F 75, B 222; the 
 former is a very limpid, ammoniacal liquid, G 0.7, B. 18.4. 
 Urea is simply CARBAMIDE (82, 12). A. W. Hofman (p. 34) 
 worked this field very successfully and gave German chemistry 
 that industrial character it has since retained. 
 
 12. ALDEHYDES (80, 9) are intermediate between acid 
 and alcohol; they contain the monovalent terminal — COH. 
 
340 
 
 LECTURE 88. 
 
 Ketones contain carbonyl united with two alcohol radicals 
 R, R'; they may be considered as ethers in which the oxygen 
 has been replaced by carbonyl. Their general expression is, 
 accordingly, R-CO — R'. If R = R' = Me = CHg we have 
 acetone, CHg. CO. CHg. 75, 12. 
 
 88. AROMATIC COMPOUNDS. 
 
 1. The aromatic compounds more READILY UNDERGO 
 SUBSTITUTIONS than the alcoholic compounds. The benzol 
 ring is wonderfully ready to exchange its hydrogen. Further- 
 more, the grouping of the carbons in the ring gives rise to an 
 almost infinite number of isomerics. 
 
 2. Treating benzol (62, 6; 74, 1) with the mixture of con- 
 centrated nitric and sulphuric acid (79, 8). we do not obtain a 
 saponifiable nitrate, but NITRO-BENZOL. Investigation has 
 shown that benzol exchanges one hydrogen for the monovalent 
 radical nitryl, NO2. At the same time, the hydrogen is 
 oxidized to water. Ce Hg thus changes to Cg H 5. NO2. The 
 monovalent radical C5 H5 is called phenyl; for it exists in 
 phenol. It may be represented by Ph. 
 
 3. NlTRO-BENZOL, Ph. NO2 is a yellowish liquid, of the 
 odor of oil of bitter almonds, for which it is substituted in 
 cheap perfumes. G 1.3, F 3 (solidifies) B 220. Acted upon 
 by nascent hydrogen (from iron and acetic acid) it is reduced 
 to ANILINE, Ph. NH2 (74, 12), which really is prepared in 
 this manner from benzol for the manufacture of aniline colors. 
 
 4. Crushed bitter almonds ferment upon the addition of 
 water, and yield a distillate which gives a crystalline precipi- 
 tate with sodium bisulphite. Accordingly, it contains an 
 aldehyde (80, 10) which is separated from the crystals by 
 means of sodium hydrate, and purified by rectification from 
 calcium chloride. It is called BENZALDEHYDE and is found 
 (Woehler, 1832) to be Ph. COH (compare 87, 12). 
 
AROMATIC COMPOUNDS. 
 
 341 
 
 5. BENZALDEHYDE, Ph. COH, is a colorless, highly 
 refractive liquid, of a pleasant, characteristic odor and an 
 aromatic taste. 1.07 at 0, B 179.5. By moderate heat it 
 gives benzol Ph H and carbonyl CO gas. Exposed to the 
 air and sun light, this aldehyde changes to its acid (87, 12), 
 namely benzoic acid, Ph.CO.OH, which see (62, 7). 
 
 6 . PHENOL (74, 6 ) upon analysis is found to be Ph. OH 
 or phenyl hydroxyl. It can be obtained, by a somewhat 
 circuitous way, from benzol. By dropping melted phenol into 
 boiling nitric acid, tri-nitro phenol C 6 H 2 (N 02)3 OH is 
 obtained, commonly called carbazotic or PICRIC ACID. It 
 forms yellow lamellar crystals, difficultly soluble in water. 
 On sudden heating it explodes. Its salts are very explosive. 
 It dyes yellow a thousand times its own weight of silk. 
 
 7. This and other nitro-phenols, when reduced, give 
 amido-phenols. The ethyl ethers hereof are called phene- 
 tidins. One of these treated with glacial acetic acid yields 
 the modern synthetic remedy PHENACETIN, forming shining 
 crystals, without odor and almost without taste; F 135. 
 It is an antipyretic. Chemically it is acet-para-phenetidin, 
 C 6 H 4 A B, where A stands for — O.C 2 H 5 and B for 
 — NH(C 2 H 30 ). 
 
 8 . After much research it has been ascertained that phenol 
 with one nitryl gives three distinct isomerics, called ORTHO-, 
 META- and PARA-NITRO-PHENOL, or designated more 
 briefly by the initmls o, m and p. It has further been ascer- 
 tained, that counting from the carbon combined with hydroxyl 
 in phenol, ortho compounds have the second, meta the third 
 and para the fourth carbon combined with nitryl. See diagram. 
 
 9. Each of the other aromatic hydrocarbons gives series of 
 compounds corresponding to the benzol compounds here 
 barely hinted at. Furthermore, the number of isomerics rapidly 
 increases with the complexity of the hydrocarbon. Thus 
 naphtalene (74, 2) gives, when one hydrogen is replaced by 
 hydroxyl, the two NAPHTOLS (74, 8 ) which are isomeric; 
 both expressed by the same formula C 10 H 7 .OH. 
 
342 
 
 LECTURE 89. 
 
 10. If a hydrogen atom next to one of the two carbon 
 atoms, common to the two benzol rings, has been replaced, 
 it is the a-naphtol. If the outer hydrogen atom has been 
 replaced, the ,i3-naphtol results. How chemists have finally 
 determined these questions of PLACE IN THE ATOM is a 
 matter entirely for special study and altogether beyond the 
 scope of this introduction. How these results are confirmed 
 and established by mechanical laws will be indicated in the 
 last ten lectures of this course. 
 
 11. Still more numerous are the isomerics obtained by 
 substitution in pyridine and chinoline (86, 11 and 74, 10, 11). 
 Ladenburg succeeded (1888) in combining normal-propyl, 
 CH3.CH2.CH2 — in the a-position (i. e. next to the nitrogen) 
 in piperidine (74, 10) ; the product was identical in all chemi- 
 cal reactions and in rotary polarization (right-handed) with 
 true coniine (64, 12). He had accomplished the SYNTHESIS 
 OF AN ALKALOID, the first on record. 
 
 12. PHENYLHYDRAZINE Ph. HN.NH2 is now an important 
 reagent for aldehydes and sugars. It is made from aniline by 
 a somewhat complex process. It is a colorless oil (G 1.19) of 
 a peculiar odor, solidifying to tabular crystals that fuse at 
 17, 5. It forms a hydrate melting at 24. The liquid turns 
 brown on exposure. Its crystallized hydro chloride keeps 
 well. One part hereof dissolved with one -and -a- half parts 
 of sodium acetate in 8 to 10 parts of water is the glucose 
 reagent used. 
 
 89. COMPLEX COMPOUNDS. 
 
 1 . In my PRINCIPLES OF CHEMISTRY AND MOLECULAR 
 Mechanics, published a quarter century ago, the chapter on 
 complex compounds (pp. 88-102) comprises mainly the 
 saccharine bodies, the alkaloids and the albuminoids. The 
 structure of these compounds has been greatly cleared up dur- 
 
COMPLEX COMPOUNDS. 
 
 343 
 
 ing the interval; even the albuminoids have yielded to the 
 labors of Schutzenberger, of Paris. 
 
 Beholding the infinite extent of this branch of chemistry, 
 and overcome by the difficulty of giving a reasonably fair con- 
 ception thereof to the mind of my reader or hearer, within the 
 narrow limits of the chapter or the hour, I select, as only sub- 
 ject for this lesson, the cup that cheers but does not inebriate. 
 Cd, 4. 
 
 2. More than five hundred million pounds of dried TEA 
 LEAVES are used by man every year, and the weight of COFFEE 
 BEANS consumed is very much greater still. In South 
 America, MATE and GUARANA correspond to tea and coffee. 
 The KOLA nut of Africa has similarly been used and has now 
 found its way to us. Why do millions of men, in all climes, 
 labor to enjoy a cup of these drinks.? And what about the 
 drink of the old Mexicans that inspired Linn^us to name the 
 tree THEOBROMA.? 
 
 3. When Sertuerner had succeeded to extract the active 
 principle of opium (64, 7-8), chemists began their investiga- 
 tion of the question just asked. The answer is not yet com- 
 plete; but the researches undertaken and the results obtained 
 are so characteristic of the CHEMISTRY OF COMPLEX COM- 
 POUNDS that we shall restrict ourselves here to this single 
 topic. 
 
 Runge (1820) extracted the active principle of coffee, the 
 glistening, acicular crystals of CAFFEINE. Robiquet, Pelletier 
 and Caventou produced the same substance about the same 
 time. In 1827, Oudry extracted the active principle of tea, 
 and called it THEINE. In 1840, Martins found caffeine in 
 Guarana, and Stenhouse found (1843) theine in mate. Lam- 
 padius found in cacao a substance similar to caffeine (Ber- 
 zelius) ; it is now called THEOBROMINE. 
 
 While extracted like alkaloids, these three substances are 
 not poisonous and not strictly alkaloids; at least they are not 
 precipitated by the general alkaloid reagents. They are 
 largely combined with tannin — especially jn tea. When the 
 
344 
 
 LECTURE 89. 
 
 hot aqueous extract is precipitated by basic lead acetate, the 
 excess of lead separated from the filtrate by hydrogen sulphide, 
 and the liquid carefully evaporated to dryness, hot alcohol will 
 extract the alkaloidal substances in question and leave them in 
 crystal form. 
 
 4. The noted Dutch chemist, Mulder, showed (1838) that 
 THEINE AND CAFFEINE ARE IDENTICAL bodies in every 
 respect. If, as some contend, tea is a protestant and coffee a 
 catholic drink, the difference must reside in associate materials 
 and not in the essential or active principles of these substances 
 which, like the fundamental principles of religion, are the same 
 in both. 
 
 Chemists were treated to another surprise when THEO- 
 BROMINE, by treatment with methyliodide in the autoclave, 
 was CONVERTED INTO THEINE, which thus appears as 
 methyl -theobromine. This change was already indicated by 
 the elementary analysis, which had given, for theobromine 
 C 7 Hg N 4 O 2 and for theine (caffeine) C Hi©, N 4 O 2 . The 
 excess CH 2 points to the additional link or methyl. 
 
 5. When either of these active substances of tea, coffee or 
 chocolate is heated on the water bath with a strong oxidizer 
 (nitric acid, chlorine water) to dryness, a yellowish residue 
 remains, which dissolves in the least possible amount of 
 ammonia with a beautiful purple color. But this is the familiar 
 MUREXIDE TEST, commonly used for the identification of 
 uric acid. 
 
 6. URIC ACID, being slightly soluble in water, gradually 
 separates from urine in crystals of characteristic forms, upon 
 the addition of the very soluble muriatic acid. By dissolving 
 the reddish crystals in alkali, discoloring with bone black, and 
 reprecipitating by a soluble acid, we obtain uric acid in 
 beautiful, colorless rhombic crystals. It is insoluble in alcohol 
 and ether, difficultly soluble in water (1 in 15,000). This 
 lack of solubility causes gouty and rheumatic troubles. 
 Piperazine is the best internal solvent for uric acid. 
 
COMPLEX COMPOUNDS. 
 
 345 
 
 7. MUREXIDE is ammonium purpurate. With one atom of 
 water it forms quadratic crystals [C5 H4(NH4)N5 O0 + H2O] 
 reflecting golden and greenish colors in sun light and dissolv- 
 ing in water to a rich purple color. It has been extensively 
 used as a dye. Boiling destroys it under evolution of ammonia 
 gas. Guano, being largely uric acid and urates, permits the 
 preparation of murexid in quantity. 
 
 In the extract of tea 
 leaves we find a corre- 
 lated nitrogenous body, 
 which does not show the 
 murexid reaction, but in- 
 stead gives the XANTHIN 
 reaction. That is, when 
 evaporated with nitric acid 
 to dryness, it turns YEL- 
 LOW to yellowish red with 
 potassa, and thereafter 
 purplish on heating. The 
 same substance, Xanthin, 
 occurs inthe animal system. 
 Its formula is C5 H4 N4 O2, 
 that of uric acid being 
 C5 H4 N4 O3. The latter 
 seems to be an oxide of the 
 former. 
 
 8. Comparing THE MOLECULAR FORMULyE of the four 
 compounds before us, and simply giving the number of atoms 
 of C, H, N, O invariably in this order, we find: Uric acid, 
 5, 4, 4, 3; Xanthin, 5, 4, 4, 2 ; Theobromine, 7, 8, 4, 2; 
 Theine, 8, 10, 4, 2. Accordingly, uric acid might be oxidized 
 Xanthin. Theobromine contains 2 CH2 and Theine 3 CH2 
 more than Xanthin. 
 
 9. Long-continued and difficult chemical researches, both 
 analytical and synthetical, have shown these substances to be 
 actually related in that way. Analytically, all THESE COM- 
 
 .# = ►. 
 
 o-i 
 
 
 
 ►o 
 
 < 
 
 '• CL 
 
 Aantfun. 
 
 > « ^>=0 
 
 o --#: #-4 
 
 ► I 
 
 * ® LiTtcAcid. 
 
 O 
 
 
-346 
 
 LECTURE 89. 
 
 POUNDS YIELD UREA H2N— CO— NH2 ; in fact, each yields 
 two molecules per atom when completely broken up. Accord- 
 ingly, each one of these four substances contains two nuclei 
 of urea. Synthetically, the three bodies have now all been 
 made from Xanthin. 
 
 10. One of the four urea nuclei (the one to the right in the 
 diagrams) is split off much more readily than the other; the 
 two are therefore not tied or bound in the same manner. In 
 many cases — such as the oxidation in the murexid test — the 
 other urea nucleus (to the left) remains united with a group 
 C3 to ALLOXAN. This Group C3 is separated as mesoxalic 
 acid C3 H2O5 when alloxan is boiled with baryta water. 
 
 11. Emil Fischer, of Berlin, has completed the synthesis 
 of these substances (Naturw- Rundschau, 1896, p. 245) in 
 conformity with the results of decomposition here indicated. 
 His investigations are expressed in the graphical formulae 
 here inserted. These diagrams have been constructed accord- 
 ing to the developed structural formula published by him. 
 Theobromine is dimethylxanthin, the methyl CH3 taking the 
 places of hydrogen at -a and b. Theine is trimethylxanthin, 
 containing an additional methyl instead of the hydrogen 
 atom at c. 
 
 12. And now, DO WE UNDERSTAND THE CRAVING OF 
 MAN FOR TEA, COFFEE AND CHOCOLATE.? By no means. 
 But we have seen how complex organic compounds are being 
 taken to pieces, and built up again. Also, how a small 
 amount of certain substances may exert great influence on the 
 body and how near the most refined food approaches some of 
 the waste products of the system. Do they perform the 
 function of the lubricant in the humon machine.? The deeper 
 we search, and the more we learn, the greater becomes the 
 mystery to the thinker. Every question answered raises at 
 least one new question, more profound and much more dilficult 
 than the one just answered. 
 
90. ORGANIC SYNTHESIS. 
 
 1. In this lesson we reach THE PRESENT BOUNDARY OF 
 CHEMISTRY. We have begun our course with the prime 
 materials furnished by plant and animal. We have extracted 
 the pure chemical compounds thereof. We have changed and 
 transformed these in many ways. We have been enabled to 
 learn much of the intimate structure of these bodies. 
 
 2. Chemists have produced NEW SUBSTANCES, con- 
 structed on exactly the same plan as these organic substances, 
 but such as nature never had produced because they cannot 
 even exist under ordinary conditions. The chemist had not 
 only to create these compounds, but also to protect them 
 against surrounding nature. We refer to the ORGANO- 
 METALLIC COMPOUNDS. 
 
 3. Bunsen’s researches (1842) on arsenic radicals (cacodyl, 
 — As Me 2 , monovalent) opened this field. Frankland produced 
 (1849) quite a group of simple ethers containing heavy metals 
 instead of oxygen, such as zinc ethyl, Zn Et 2 . In 1869 
 FRIEDEL began his extended researches, establishing a 
 CHEMISTRY OF SILICON COMPOUNDS parallel to that of the 
 carbon compounds or organic chemistry, including silicon 
 chloroform and ethers, and determining the true constitution 
 of all silicon compounds, from that of quartz onward! 
 
 4. These organo-metallic compounds almost invariably 
 BURN IN CONTACT WITH THE ATMOSPHERE. They have 
 to be prepared and maintained in an artificial atmosphere free 
 from oxygen. Their preparation is both DIFFICULT AND 
 DANGEROUS. The lessons they have taught are most 
 important. See my paper on Central Substitution, Comptes 
 Rendus, T. 115, p. 314; 1892. 
 
 5. In the chemical changes of true organic compounds, 
 that is, such as have been extracted from vegetable and 
 animal materials, as well as in the formation of organo- 
 metallic compounds, no really new reactions have been resorted 
 
348 
 
 LECTURE 90. 
 
 to or discovered. ALL ORGANIC CHEMICAL REACTIONS 
 ARE IN NO MANNER DIFFERENT FROM THOSE OF INOR- 
 GANIC CHEMISTRY. The forces brought into play being less, 
 and the compounds being generally more complex, greater 
 delicacy in the chemical operations is ordinarily essential to- 
 success. 
 
 6. Hence it would seem that any true organic compound,, 
 as produced in the living plant or animal, ought to be pro- 
 ducible in the chemical laboratory by SYNTHESIS FROM 
 INORGANIC MATERIALS, provided the chemist be skillful 
 enough and provided he possess sufficient knowledge. But as a 
 matter of fact, no truly organic compound had been produced by 
 synthesis from the elements up to the middle of this century. 
 
 7. At that time LIEBIG was considered the leading chemist 
 of the world. In his “Chemical Letters” of 1844 he 
 DECLARED IT IMPOSSIBLE to produce any organic compound 
 from the constituent elements. These letters had a wide cir- 
 culation in all countries, having been translated into most 
 languages. 
 
 8. Liebig was well aware that his friend and oft-time co- 
 laborer Woehler had produced (1828) UREA from inorganic 
 materials (84, 4). This compound was, however, looked 
 upon as an organic waste product merely; besides, the 
 cyanogen compounds used in the transformation might be con- 
 sidered either organic or inorganic themselves. 
 
 9. Liebig’s declaration would have been in exact accord- 
 ance with fact, if he had said it was “impossible for him”' 
 to produce organic compounds by synthesis from the elements. 
 He erred in assuming that what was impossible for him would 
 also be impossible for all other chemists, and forever! 
 
 10. The man who was soon to do what Liebig declared an 
 absolute impossibility was already studying chemistry at Paris. 
 Six years later he became attached to the College de France 
 as an assistant. Ten years after the declaration of Liebig, he 
 
ORGANIC SYNTHESIS. 
 
 349 
 
 had accomplished one of the impossibilities of Liebig, the syn- 
 thesis of the fats (78, 12) . In 1860, the Impossibility of Liebig 
 was replaced by BERTHELOT’S ORGANIC CHEMISTRY 
 FOUNDED ON SYNTHESIS. 
 
 This work has so completely changed the aspect of chemical 
 science, that it is unnecessary to enter upon details. His 
 method of operation, as well as of thought, have become part 
 of the science. A most fascinating exposition thereof has 
 been given by Berthelot himself in his CHEMICAL SYNTHESIS, 
 Paris, 1876; a volume forming part of the International Scien- 
 tific Library. 
 
 11. The most brilliant work of chemical synthesis done in 
 Germany has been accomplished by EMIL FISCHER, now at 
 the University of Btrlin. His discovery of the reaction of 
 glucose on phenylhydrazin (88, 12) furnished him the instru- 
 ment that lead to THE SYNTHESIS OF ALL THE SUGARS. 
 His admirable work on uric acid and the allied compounds has 
 been considered in our preceding lesson. 
 
 12. And now— WILL SYNTHESIS FROM INORGANIC 
 MATERIALS EVER DO AWAY WITH OUR DEPENDENCE ON 
 THE CELL-LABORATORY OF PLANT AND ANIMAL.? In cer- 
 tain special lines, yes; on the whole, most likely an emphatic 
 no. The plants are greater “specialists” than our chemists 
 ever are likely to be. The power they use is the cheapest of 
 all, and the best; it is the glorious sunshine that fills the 
 world so long as man shall live on earth — for he will have to 
 die when the sun shall begin to grow dim. The raw materials 
 of the cell-chemists are also the cheapest of all, namely rain 
 and air. To give plants the best chance to furnish us the 
 highest possible returns, we should work with our hands in 
 field and garden, should plow and plant, harrow and hoe, in 
 order that we may glean and garner for self and others, for 
 home and. market. And as in this labor we come in touch 
 with Mother Earth, and draw deeply the air just purified by 
 that beam of power from Father Sun, we become strong in 
 body, and pure in heart, while our soul is filled with Peace 
 and Faith and Hope. 
 
91. THE ATOM-WORLD. 
 
 1. “Let us remember, please, that the search for the 
 constitution of the world is one of the greatest and noblest 
 problems presented by Nature.” This word of GALILEO, 
 taken from his second dialogue on the Systems of the World, 
 we have placed as motto on the front page of this book. 
 
 2. The Great World, the MACROCOSMOS of the Ancients, 
 was but the flat earth, surrounded by the sea, and lit up by 
 sun and stars. To Modern Science it is the wonderful, infinite 
 All, in which the earth is but an atom. The mechanical 
 structure of this world Galileo had in mind. He most success- 
 fully assisted in the search for its constitution; and was 
 rewarded by persecution, prison and torture. 
 
 3. To the searching eye of Science, the atom itself becomes 
 a world; -tit is the true MICROCOSMOS. The search of its 
 constitution offers no less great and noble a problem than that 
 of macrocosmos. With thermometer and goniometer we have 
 learned to measure the dimensions of the atoms, precisely as 
 astronomers measure the dimensions of the planets with 
 pendulum and theodolite. C. R., T. 76, p. 1594; 1873. 
 
 4. The guiding rule in this, our study of microcosmos, is 
 the same that has laid open the constitution of macrocosmos: 
 it is MECHANICS, the mathematical expression of the action 
 of matter through space. This action is independent of the 
 absolute dimensions. The laws of motion apply equally to 
 large and small objects. The planet is but an atom in the 
 world; the silicon atom is half the world in quartz. 
 
 5. The science of mechanics was founded by ARCHIMEDES, 
 of Syracuse, twenty-five centuries ago. He established the 
 laws of statics, the science of equilibrium. GALILEO (p. 18) 
 laid the foundations of dynamics, the science of motion. 
 HUYGHENS (p. 20) worked out the laws of rotations and revo- 
 
THE ATOM-WORLD. 
 
 351 
 
 lutions. From NEWTON’S Principia to LAPLACE’S Celestial 
 Mechanics, this search for the constitution of macrocosmos has 
 been perfected. 
 
 6. The beginning of the mechanics of microcosmos may be 
 traced back, even to Galileo himself. About the middle of 
 this century the MECHANICAL CONSTITUTION OF THE 
 GASES seemed to open the field anew. But to the mathe- 
 matician, the molecule remained merely an elastic ball, while 
 the chemist, dripping with tar, made flat diagrams of com- 
 plex molecules in utter disregard of the laws of mechanics 
 which he did not care to know. 
 
 7. The extreme one-sidedness of German chemistry of the 
 present, which has compelled the government to fill the two 
 principal chemical professorships in Germany with a Russian 
 and a Hollander, is also noted in the SENSATIONAL DECLA- 
 MATIONS of one of their most voluminous writers against the 
 great masters of mechanical science, from Newton to Laplace, 
 and his habitual derision of mechanical conceptions in chemical 
 research. 
 
 8. We would take no notice of these strange declamations 
 if they were not taken as representing that GERMAN SCIENCE 
 WHICH THE WORLD JUSTLY REVERES. Unmindful of 
 Liebig’s equally unfounded authoritative declaration of the 
 impossibility of the true synthesis of genuine organic com- 
 pounds, young Berthelot performed these syntheses from the 
 elements. In the same manner, the author has continued to 
 establish the constitution of compounds by applying the 
 mechanics of Galileo, Huyghens, Newton and Laplace though 
 these masterminds are denounced by the chemists of the 
 University of Leipzig who writes so much that his thoughts 
 evidently cannot keep up with his pen. See my True Atomic 
 Weights, pp. 42—46; 1894. 
 
 9. In the gaseous state, the molecules move freely in space 
 until they hit the walls of the containing vessel or another 
 particle. The flight of the gaseous molecule is free, unre- 
 
352 
 
 LECTURE 91. 
 
 strained, like the motion of a projectile or that of a cosmical 
 body. The motion of the gaseous molecules therefore must 
 conform to the established LAWS OF FREE MOTION. 
 
 10. The motion of projection or translation is associated 
 with a rotation around one of the permanent axes. For one of 
 these axes, the moment of inertia (mass) is greatest, for the 
 other it is smallest. In continued motion, the body will neces- 
 sarily come to rotate about the first of these axes, it being the 
 most stable. IN THE GASEOUS STATE THE PARTICLES 
 (MOLECULES) HAVE A MOTION OF TRANSLATION AND 
 ROTATE AROUND THEIR SHORTEST AXIS (i. e., the perma- 
 nent axis for which the moment of inertia is the greatest). 
 
 11. This is the motion of all the cosmical bodies. These 
 motions are best shown by the BOOMERANG. Small card 
 boomerangs allow the instructive and elegant lecture experi- 
 ment, the two motions being readily seen by all. The experi- 
 menter, after a little practice, needs only one boomerang, 
 since it promptly returns to him every time. By attaching 
 balls, chain, hoop, flask with water and colored ether, or water 
 and mercury, to a catgut string, and rapidly TWIRLING the 
 upper end hereof, the rotation will be final around the shorter 
 axis, i. e., the one for which the moment of inertia is greatest. 
 
 12. In the SOLID STATE, particles merely oscillate. MELT- 
 ING, THEY BEGIN TO ROTATE, necessarily AROUND THEIR 
 LONGEST AXIS, being their axis of minimum moment of 
 inertia. Fleated high enough, particles will finally be pro- 
 jected from the surface of the liquid, and move freely through 
 space as just described. This MECHANICAL DESCRIPTION 
 OF THE THREE STATES OF AGGREGATION the author has 
 published a quarter of a century ago, and proved it to be true 
 by many deductions, a few of which will now be given. 
 
92. PRISMATIC ATOMS AND BOILING. 
 
 1. AT THE BOILING POINT, the particles are projected 
 from the liquid in numbers sufficient to BALANCE THE 
 PRESSURE OF THE ATMOSPHERE. At the same pressure, 
 all boiling liquids are necessarily in corresponding condition. 
 We need, to connect them, only to study the relation 
 between pressure and boiling point for any one liquid. 
 C. R., T. 112, p. 998; 1891. 
 
 2. To study the FORM OF ATOMS, it is necessary to begin 
 with groups of bodies known to be of the same kind. Such 
 groups we have in the HOMOLOGOUS SERIES of modern 
 organic chemistry. Any given alcohol radical R added to 
 — CH 2 .H forms a paraffin; to — CH 2 .OFI an alcohol; 
 to — CO.H an aldehyde; to — CO. OH an acid; to — CH 2 .CI 
 a chloride, etc., etc. Lecture 87. 
 
 3. Let us compare say the HOMOLOGOUS ALCOHOLS, 
 wherein R = Cm H2m+i. In all these compounds, the active 
 terminal, i. e. that part which can react chemically, is the 
 same, namely — CH 2 .OH. It weighs 31. The other part 
 Rm may be written H + m (CH 2 ). The entire alcohol 
 atom therefore weighs 32-{-14m, where m is the total number 
 of carbon atoms less one. 
 
 4. All the OTHER HOMOLOGOUS SERIES mentioned may 
 be expressed by corresponding formulae. The paraffins by 
 14+14m. The aldehydes by 30-(-14m. The acids by 46+14m. 
 The chlorides by 48.5+14m. The bromides by 93+14m. 
 The cyanides by 49+14m. The amines by 31+14m. 
 
 5. These substances can be readily changed chemically 
 one into the other — both by changing the radical of m links 
 CH 2 and especially by changing the active terminal. It may 
 not be elegant, but it certainly is very correct, to compare the 
 TERMINAL to the head, the RADICAL to the vertebrae of an 
 animal— say a snake. The carbon of the link CH 2 would rep- 
 resent the vertebra, the two hydrogens the ribs attached thereto. 
 
354 
 
 LECTURE 92. 
 
 6. Now all chemists agree that these CHa are joined each 
 way by a simple link or valence. But how is the form of the en- 
 tire radical: rigid, forming a STRAIGHT LINE, or spiral like a 
 CORKSCREW (86, 4 to 6) . Our great German chemists do not 
 know, and therefore declare this question is insoluble, and 
 should not be approached. This admirable system throws odium 
 on anyone who dares to attempt the solution of such a question. 
 They even excuse Berzelius (E. Meyer, History, p. 238, Engl, 
 edition 1891) from having thought such a problem soluble. 
 
 7. But reading our GRAND MASTER once again (91, 1) 
 we venture to tread where der Herr Geheimrath has not 
 been. We put the question once more clearly before our 
 eyes: do these m -links of the radical of modern chemists 
 form a rigid, straight line, or do they not. 
 
 8. Now, nature has the rather human habit of giving A 
 PLAIN ANSWER TO A PLAIN QUESTION; but, at the same 
 time, she only answers yes or no, and thus gives us no 
 answer at all unless we have taken the trouble to learn how 
 to ask the question. Really, the main difficulty of investiga- 
 tion is to learn to ask the question. That is a mental problem. 
 Our apparatus cannot help us therein. 
 
 9. Now TWO LINKS CH 2 form a straight line; for two 
 points determine such a line. These two points are the 
 centers of gravity; weight 14 each. Let their distance be 
 taken as unity. The moment of inertia of this 2 CH 2 will 
 then be 7 exactly. If the radical forms a straight line, the 
 moment of inertia for 3 links CH 2 will be 28, for 5 links will 
 be 112, for 7 links 364, for 9 links 812, and so forth. The 
 moment of inertia is the sum of the each weight into the 
 square of its distance from the axis, here the center of gravity 
 or the middle atom. 
 
 10. According to 91,10, THE BOILING POINT must be 
 some function of this moment of inertia. If the form of the 
 radical be not straight, the moments of inertia will increase at 
 a much less rapid rate; that popular tetrahedral -corkscrew 
 would show very slowly growing moments of inertia for in- 
 creasing values of m. On plates 76 and 77 we have copied the 
 
PRISMATIC ATOMS AND BOILING. 
 
 355 
 
 graphical representation of the facts observed (boiling points) 
 and our function of the moments of inertia (simply related to 
 the logarithm of number of carbon atoms). See note on 
 logarithm below. 
 
 11. The most NECESSARY DATA have been given in our 
 papers kindly presented by Berthelot to the Academy of 
 Sciences of Paris, and inserted in full in the Comptes Rendus 
 of that Academy for 1892. Plates 76 and 77 are simply 
 re-prints from the Comptes Rendus. The very curves, how- 
 ever, suffice to give the answer, without entering upon the 
 details of calculation, the leading formulae for which are 
 inserted on the plates. 
 
 12. The answer to the question is complete and decisive. 
 The alcoholic radical Cm Rm+i forms a straight line, so far as 
 the maximum moment of inertia is concerned. ALL SATU- 
 RATED ALCOHOLIC COMPOUNDS ARE LINEAR, consisting 
 of the rectilinear tail or series of CH 2 links and terminating 
 in the head chemically characterizing the compound as 
 paraffin, acid, chloride, and the like. 
 
 Note. — The log n of our plates means the logarithm of the total 
 number n of carbon atoms of the compound. The actual values, taken 
 from any logarithm table, are given below: 
 
 No. 
 
 Log. 
 
 No. 
 
 Log. 
 
 No. 
 
 Log. 
 
 No. 
 
 Log. 
 
 No. 
 
 Log. 
 
 
 
 10 
 
 1. 000 
 
 20 
 
 1. 301 
 
 30 
 
 1.477 
 
 40 
 
 1.602 
 
 I 
 
 0.000 
 
 1 1 
 
 1. 04 1 
 
 21 
 
 1.322 
 
 31 
 
 1. 491 
 
 41 
 
 1.613 
 
 2 
 
 0.301 
 
 12 
 
 1.079 
 
 22 
 
 1.342 
 
 32 
 
 1-505 
 
 42 
 
 1.623 
 
 3 
 
 0.477 
 
 13 
 
 1.114 
 
 23 
 
 1.362 
 
 33 
 
 1-519 
 
 43 
 
 1.634 
 
 4 
 
 0.602 
 
 14 
 
 1.146 
 
 24 
 
 1.380 
 
 34 
 
 1-532 
 
 44 
 
 1.644 
 
 5 
 
 0.699 
 
 15 
 
 1.176 
 
 25 
 
 1.398 
 
 35 
 
 1-544 
 
 45 
 
 1-653 
 
 6 
 
 0.778 
 
 16 
 
 1.204 
 
 26 
 
 I -415 
 
 36 
 
 1-556 
 
 46 
 
 1.663 
 
 7 
 
 0.845 
 
 17 
 
 1.230 
 
 27 
 
 1-431 
 
 37 
 
 1.568 
 
 47 
 
 1.672 
 
 8 
 
 0.903 
 
 18 
 
 1-255 
 
 28 
 
 1.^47 
 
 38 
 
 1.580 
 
 48 
 
 1. 681 
 
 9 
 
 0-954 
 
 19 
 
 1.279 
 
 29 
 
 1.462 
 
 39 
 
 I -591 
 
 49 
 
 1.690 
 
 Such a table of logarithms can be obtained bv noting the consecutive 
 excursions of the pointer of a fine chemical balance during ten to thirty 
 minutes. The number of the oscillation and the corresponding excursion 
 form the logarithmic curve. 
 
 . We here have referred to the normal compounds exclusively. We also 
 designedly have taken the weight instead of the mass in the moments of 
 inertia, for obvious reasons. 
 
93. ATOM LINKAGE AND FUSING. 
 
 1. Having determined the atoms of all alcoholic serials to 
 be rectilinear, so far as the arrangement of the centers of 
 gravity of their links CH 2 is concerned, the next question is, 
 how are the carbon atoms linked? 
 
 2. The rectilinear form established leaves only TWO POS- 
 SIBLE MODES OF LINKAGE of the carbon atoms in the alco- 
 holic radical. The carbon atoms may link end-to-end, or 
 face-to-face. That is, since they have some form, say like a 
 watch, they may attract end-to-end, or face-to-face. 
 
 3. In the END-TO-END POSITION the carbon atoms 
 could revolve and the hydrogen atoms of CH 2 might face any 
 direction. The resulting compound would be far from rigid. 
 Yet we have the best of reasons to suppose that element 
 atoms in compound atoms are held rigidly in place, like mole- 
 cules in a crystal. The end-to-end position is therefore not 
 probable, a-priori. 
 
 4. In the FACE-TO-FACE POSITION of the carbon atoms, 
 the structure would be rigid, the hydrogen would alternately 
 turn as the carbon does. The entire atom would be most 
 symmetric as well as rigid. This is a-priori the most probable 
 method of linkage of the carbon atoms in alcoholic, and in 
 fact, in all organic compounds. 
 
 5. Let us again submit the question to nature, and first 
 formulate the most probable case. The carbon atoms would 
 occupy positions as the types here printed. The points of 
 
 attraction of atoms A, C, E, 
 
 C 
 
 G 
 
 etc. would be directed down- 
 ward towards the correspond- 
 ing points of B, D, F, etc., 
 directed upwards. 
 
ATOM LINKAGE AND FUSING. 
 
 357 
 
 6. IF THE TOTAL NUMBER OF ATOMS OF CARBON BE 
 EVEN, the axis containing the center of gravity of the com- 
 pound will' run exactly midway between the two lines. If 
 the distance be called 2, the moment of inertia will be simply 
 equal to the atomic weight, the distances of all atoms from the 
 axis being unity. 
 
 7. BUT IF THE TOTAL NUMBER OF CARBON ATOMS 
 BE ODD, the result will be entirely different. Suppose we 
 
 have three atoms only. In that case 
 A C the center of gravity evidently is much 
 
 a nearer the two atoms A and C than the 
 
 single atom B. In fact, everyone under- 
 stands the space is divided as one to two. The distance from 
 the geometrical middle to the real axis is one -third unit. 
 
 8. If the total number be five atoms of carbon, the four 
 will balance exactly. But the fifth will evidently draw the 
 
 center of gravity one -fifth unit up from 
 ACE the middle line. That is, the perma- 
 a Q nent axis of rotation, which passes 
 
 through the center of gravity of the 
 system, lies one-fifth unit of distance away from the geomet- 
 rical axis or middle line. For seven atoms it will be one- 
 seventh, and so forth. 
 
 9. Now it is a simple principle in mechanics, that the 
 moment of inertia of any body, or system of bodies, is smallest 
 for the axis passing through the center of gravity. For ANY 
 Axis at any distance PARALLEL to the first axis, the moment 
 is greater by a quantity proportional to the SQUARE of this 
 distance. 
 
 10. Consequently, the moment of inertia for the alcoholic 
 serial compounds considered, in reference to the permanent 
 axis parallel to the length of the system, increases proportional 
 to the total atomic weight of the entire system; but for com- 
 pounds of an ODD NUMBER N OF CARBON ATOMS the 
 moment of inertia is diminished by a quantity proportional to 
 the square of one -nth of the total number of carbon atoms. 
 
358 
 
 LECTURE 93. 
 
 11. But this moment of inertia determines the fusing point 
 of compounds (91, 12). Hence the FUSING POINT OF ALCO- 
 HOLIC SERIALS IS SMALLER FOR COMPOUNDS HAVING AN 
 ODD NUMBER OF CARBON ATOMS, THAN FOR THOSE 
 HAVING AN EVEN NUMBER of carbon atoms; the difference, 
 being inversely proportional to the square of the number of 
 carbon atoms, will rapidly diminish as n increases and vanishes 
 when n becomes sufficiently large. 
 
 12. But this is precisely the case for the paraffins, the 
 fusing points for which have been presented in curves D and 
 C of Fig. 6, page plate 74, according to the observations of 
 Krafft. See for fuller data, Comptes Rendus, May 19, August 
 17, and November 22, 1891. HENCE THE CARBON ATOMS 
 ARE JOINED FACE-TO-FACE in the organic compounds. 
 No such marvelous and hitherto utterly inexplicable differences 
 could occur in the end-to-end position between compounds 
 containing even and odd numbers of carbon atoms. 
 
 The Fatty Acids show the same differences in a most striking man- 
 ner. These remarkable differences have puzzled modern chemists 
 greatly. The deductions given make the determinations of the fusing 
 points an experimentum crucis for the linkage of the carbon atoms, as 
 here shown. 
 
 For the fatty acids, the fusing points F and the total number n of car- 
 bon atoms are given in the following little table. It will be noted that 
 the melting point of the odd-numbered acid is from 3 to 2 below that of 
 the preceding even-numbered acid, while the next even-numbered acid 
 is from 20 to 6 degrees higher : 
 
 n 
 
 F 
 
 n 
 
 F 
 
 n 
 
 F 
 
 8 
 
 16.0 
 
 14 
 
 54 
 
 20 
 
 75 
 
 9 
 
 12 
 
 15 
 
 51 
 
 21 
 
 72 
 
 10 
 
 31-4 
 
 16 
 
 62 
 
 22 
 
 78 
 
 1 1 
 
 28 
 
 17 
 
 60 
 
 23 
 
 
 12 
 
 43-6 
 
 18 
 
 69 
 
 24 
 
 80.5 
 
 13 
 
 40.5 
 
 19 
 
 66.5 
 
 25 
 
 77 
 
94. ATOMIC VOLUME. 
 
 1. The atomic volume of any compound in the solid or liquid 
 state is the volume, in cubic centimeters, occupied by one 
 gramme-atom of the substance. THE ATOMIC VOLUME OF 
 WATER IS 18; for each cubic centimeter of water weighs one 
 gramme, and the atomic weight of water is 18. 
 
 2. The specific gravity of any substance being the weight, 
 in grammes, of one cubic centimeter of that substance (2, 11), 
 it follows that THE ATOMIC VOLUME IS OBTAINED BY 
 DIVIDING THE SPECIFIC GRAVITY OF THE SUBSTANCE 
 INTO ITS ATOMIC WEIGHT. For water, G is 1, the atomic 
 weight 18; hence the atomic volume is 18 cc per gramme-atom. 
 
 3. Plate p. 394 gives the specific gravity for the liquid 
 PARAFFINS Cn H 2 nX 2 from n 5 to n = 35. The points con- 
 nected by dots form the SPECIFIC GRAVITY CURVE of this 
 homologous series. The curve first rises rapidly, then turns, 
 and from n = 16 changes but very little. That is, the 
 specific gravity of the higher paraffins is almost constant. 
 They could not be distinquished by their gravity. 
 
 4. Figure 5 on the same plate represents the ATOMIC (or 
 molecular) VOLUME of these paraffins. It will be noticed that 
 this curve is practically a straight line. Only for the lower 
 compounds (from 5 to 10) is the volume slightly in excess of 
 the corresponding points on the straight line. For 22 the 
 volume is 400; hence practically 18 for each link CH 2 . 
 
 5. The higher paraffin atoms accordingly occupy a PRIS- 
 MATIC SPACE equal to as many times the atomic volume of 
 water as the paraffin contains carbon atoms or links CH 2 . The 
 very deviation for the lower members, the author has shown 
 to be due to the two terminal hydrogen atoms, the influence 
 of which rapidly becomes insensible with the increase of the 
 number of carbon atoms. C. R., T. 113, p. 37, Equat. 22; 1891. 
 
360 
 
 LECTURE 94. 
 
 6. The equality of the atomic VOLUME OF EACH LINK 
 CH 2 in paraffins with that of water has also been recognized 
 by the author fully thirty years ago. The atomic volume of 
 alcohols and acids being approximately one water volume in 
 excess of that or the corresponding paraffin, shows that the 
 terminals of — CH 2 OH in alcohols and of — CO. OH in acids 
 make the hydroxyl OH nearly equal to the link CH 2 . 
 
 7. Accordingly, all these homologous serials may be looked 
 upon as forming PRISMATIC ATOMS of the same cross-section 
 (very nearly), and differingonly in length. The cross-section 
 evidently equals that of the water atom, which becomes a 
 convenient unit. The cross-section we have called ATOMARE, 
 the length ATOMETER (Atomechanics, 1867). The atometer 
 of a paraffin is n, that of an acid or alcohol n + 1, if n repre- 
 sents the total number of carbon atoms, arranged in a single 
 straight line (normal). 
 
 8. THE ATOMIC VOLUME of homologous series MAY BE 
 CALCULATED by two methods, namely, the statical and the 
 dynamical method (C. R., T. 113, p. 36; 1891). In the 
 STATICAL METHOD, the volume of the atomic prism is 
 determined from its section, which is constant in the same and 
 correlated series, and its length. The case of the paraffin 
 series is given as example. 
 
 9. In the more general and more interesting DYNAMICAL 
 METHOD, the rotary motion of atoms around their longer axis 
 is made use of; it is, of course, applicable to liquids only. In 
 this case the atom -volume is a cylinder of revolution, the base 
 of which is the circle described in the rotation, while the length 
 is that of the axis itself. 
 
 10. This method has been applied to OVER SIXTY ETHERS 
 for which the necessary data are known. The results of the 
 calculations agree admirably with the observations. The 
 cross section of these ethers is one -third larger than that of 
 the paraffins. This is the expression of the fact that the 
 ethers contain the link O, connecting the radicals, projecting 
 
ATOMIC VOLUME. 
 
 m 
 
 above the CH 2 one-third its height. See C. R., T. 113, 
 p. 37; 1891. 
 
 11 . One of the most remarkable confirmations of this 
 prismatic or cylindrical form of the atoms of serial organic 
 compounds has been found in the laws of the MAGNETIC 
 ROTATION of polorized light produced in liquids. In looking 
 over recent work of W. H. PERKIN, who has furnished most 
 elaborate and extensive observations in this field, numerous 
 further confirmations are noticed. C. R., T. 113, p. 500; 
 1891. 
 
 12. The exposition of this subject of atomic volume in 
 leading MODERN GERMAN WORKS is really astonishing. 
 German scientists used to be proud to know work done in 
 other countries as well as that done within the limits of the 
 old Fatherland. At present, this has become merely a historic 
 reminiscence. In Ostwald’s Biggest Book on Chemistry, the 
 crude ideas of Kopp are still law, and the search for the fixed 
 atomic volume of each element atom is lustily continued as it 
 was begun fifty years ago. 
 
 95. ISOMERIC ATOMS. 
 
 1. Having established, by induction, the structure of 
 alcoholic compounds, we may now make use of the easier 
 METHOD OF DEDUCTION to establish some of the principal 
 laws governing the physical properties of the compounds. 
 
 2. The first compounds which invite our attention are the 
 Isomerics (84). They result from ISOMERIC ATOMS, namely 
 different structures built up from the same number of atoms 
 of the same elements, in accordance with the laws of linkage. 
 
 3. Thus the paraffin NORMAL PENTANE C 5 H 12 , boils at 
 about 38 degrees. It is normal, having its five links all in one 
 straight line. Chemical treatment has failed to remove 
 shorter links from the same. It has no lateral branches. 
 
362 
 
 LECTURE 95. 
 
 4. But the same five carbon atoms might be so linked as 
 to have one or more lateral branches. If it has only one CH 2 
 lateral, and near the terminal, it is called ISO- PENTANE. 
 This hydrocarbon boils at 30 degrees, fully 8 degrees lower 
 than normal pentane. 
 
 5. Finally four lateral branches CH3 might be bound to 
 one central carbon, from the same 5 carbon and 12 hydrogen 
 atoms. This isomeric compound is called TETRA-METHYL 
 METHANE. It boils at 9.5, about 30 degrees below the 
 normal pentane. It is liquid at common temperatures, but 
 fuses at —20. 
 
 6. Now it needs only a moment’s consideration to under- 
 stand these REMARKABLE DIFFERENCES. As the carbons 
 are placed in the lateral branches, their distances from the 
 center become less; consequently, the moment of inerita, 
 depending on the square of these distances, must greatly 
 diminish. Hence the boiling point must be lowered corre- 
 spondingly (92, 10 -12). See Plate, page 78. 
 
 7. For example, the MAXIMAL MOMENT OF INERTIA 
 (omiting single terminal hydrogens) of normal pentane is 
 10 CH2 = 140, while that of tetra- methyl methane is 
 only 4 CH2 = 56, or about one-third. In the first we have 
 two links CH2 at the distance two, giving a moment of inertia 
 4. CH2 each. In the final isomeric, these two links are at 
 the unit of distance, and only give the moment I.CH2 each. 
 This fully explains the changes in boiling points. 
 
 8. As links are made lateral, the MINIMAL MOMENT OF 
 INERTIA for the main or larger axis will be greatly increased 
 with their increased distance from that axis. Accordingly, 
 tetra- methyl methane melts at a temperature at which normal 
 paraffins of even twice that number of carbon atoms remain 
 liquid. 
 
 9. In the same manner, the ISOMERIC ALCOHOLS con- 
 taining 4 carbon atoms are all liquids except the trimethyl 
 carbinol, having three lateral arms CH 3 . It forms rhombic 
 crystals melting at 28 degrees. In this atom, the longer axis is 
 
ISOMERIC ATOMS. 
 
 3()3 
 
 CH3-CH-OH and to the carbon of the middle the two CHg are 
 linked, greatly increasing the moment of inertia for this axis. 
 
 10. MY FIRST PUBLICATION on this subject appears in 
 the Proceedings of the American Association for the Advance- 
 ment of Science for 1868 (Chicago meeting). Complete 
 mathematical formulae were sent in my Beitrage to the Ger- 
 man Chemical Society at Berlin in 1872, of which 1 was a 
 rnember. Several papers of mine were presented by Berthelot 
 to the Academy of Sciences of Paris and published in the 
 Comptes Rendus from 1873 on. See T. 113, p. 798; 1891. 
 
 11. DR. ALEXANDER NAUMANN, Professor of Chemistry 
 at the University of Giessen, Germany, was one of the 
 paid writers for the Jahresbericht. He misrepresented and 
 condemned my paper of 1868 on this subject in the Jahres- 
 bericht. In 1873 he discovered my law over again as his own, 
 and his discovery was promptly published in the Berichte of 
 the German Chemical Society of Berlin. In all German 
 chemical publications this law is credited to Naumann, even 
 in W. Markwald’s “Beziehungen” which were crowned with 
 a prize by the University of Berlin, in 1888, under the auspices 
 of Geheimrath A. W. Hofmann. 
 
 Thus the young German writers on the Jahresbericht make 
 their discoveries, and no protest is raised by German scien- 
 tists. Until that is done they must be considered as endorsers 
 of that practice. 1 demanded my name erased from the list of 
 members of the German Chemical Society (March 27, 1874). 
 See my Beitrage, Leipzig, 1892. 
 
 12. It will readily be seen that the structure now estab- 
 lished fully accounts for the RIGHT- AND LEFT-HANDED 
 (geometric) ISOMERICS, and therefore determines the charac- 
 ter of rotary polarization. A simple construction of the 
 stereographic formulae of the tartaric acids will exemplify this. 
 Compare figures 1, 2, 3, page 394. The face-to-face linkage 
 of carbon is most essential also in this matter. The interest- 
 ing hexachlorides of Benzol, due to Friedel, obtain their fullest 
 importance in this construction. 
 
96. ATOMIC ROTATIONS. 
 
 1. The reality of ATOMIC ROTATIONS in the liquid and 
 gaseous states is also most conclusively demonstrated by the 
 results obtained as specific heat (39 and 40) of substances in 
 these states. We shall first consider the specific heat of gases. 
 
 2. The specific heat of a gramme-molecule of any gas or 
 vapor is the number of gramme -degrees of heat required to 
 raise the temperature thereof one degree (centigrade). If the 
 volume be kept constant, the gas does no external work; if 
 the PRESSURE BE KEPT CONSTANT, the gas expands and 
 thus does external work. According to G. Schmidt, this 
 EXTERNAL WORK amounts to 2 calories (gramme degrees). 
 
 3. While the temperature changes, the particles may also 
 act upon one another, and thus do some INTERNAL WORK. 
 For perfect gases, like oxygen and hydrogen, this amount is 
 not measLireable, but for vapors it may be of appreciable mag- 
 nitude. We will represent it by the symbol w. 
 
 4. THE ACTUAL ENERGY OF MOTION is represented in 
 the vibration of the atoms, the motion of translation and of 
 rotation of the entire molecule. The first depends evidently 
 upon the number of atoms in the molecule. Naumann con- 
 siders it equal to as many calories as the molecule has atoms; 
 say n. The motion of translation represents 3 gramme 
 degrees, according to Clausius. 
 
 5. THE MOTION OF ROTATION requires an amount of 
 energy proportional to the moment of inertia, 1 of the mole- 
 cule; hence we can call it k I calories per gramme molecule 
 (Comptes Rendus, T. 76, p. 1358; 1873, and Principles of 
 Chemistry, 1874; p. 118). For many gaseous alcoholic com- 
 pounds we have found k one -eighth of a calory. 
 
 6. Thus the total specific heat (under constant pressure) 
 of a gramme molecule of any GAS OR VAPOR becomes 
 
 S = 5-|-w + n + kl 
 
ATOMIC ROTATIONS. 
 
 305 
 
 For LIQUIDS, the same formula will obtain, except that the 
 external work is insignificant for a degree, and that the moment 
 of inertia i is taken for the longer axis. Hence 
 S' = 3 + w + n + ki 
 
 7. The gases and vapors considered by me in 1873 agree 
 excellently with this formula S and therefore PROVE THE 
 ROTATION OF THE MOLECULES of gases and vapors around 
 that permanent axis for which the moment of inertia is a 
 maximum. We shall come back to this subject in the next 
 lecture. 
 
 8. THE ETHERS OF THE FATTY ACIDS have been found 
 to be truly prismatic bodies (94, 10). Their moment of inertia 
 is accordingly directly proportional to their length, the cross- 
 section being the same throughout each one and for all. 
 Hence the specific heat per unit of weight must be the same 
 for all these ethers (C. R., T. 113, p. 469; 1891). 
 
 9. R. SCHIFF has found this specific heat for all equal to 
 0.442; he has studied 27 of these ethers (1. c.) Ostwald 
 declared this result to be “most unexpected.” But we see 
 that it is simply the expression of the equal cross-section of 
 all these prismatic bodies. THE DETERMINATION OF SCHIFF 
 therefore are a direct demonstration of the rotation of the 
 molecules of these liquids around their longer axis. 
 
 10. FOR SOLIDS, the term containing the moment of 
 inertia disappears, because the molecules of solids do not 
 rotate. The expression in 6 is reduced to 
 
 S' = 3 + w + n 
 
 where the internal work w now becomes very considerable. 
 These results, being old and long established, need not be 
 considered here. 
 
 11. The specific heat of the SOLID ELEMENTS are equal, 
 namely nearly 6 ; hence the internal work is about 3. Ber- 
 thelot has first (1873) pointed out that elements herein radi- 
 cally differ from all compound matter. 1 have shown (1892; 
 
366 
 
 LECTURE 97. 
 
 C. R., July 25) this to be due to the fact that the element- 
 atoms oscillate as a unit, or that THEIR COMPONENT PARTS 
 ARE INVARIABLY FIXED, not mutually movable. 
 
 12. Recently Berthelot (C. R. Jan. 18, 1897) has care- 
 fully compared the specific heat of the elementary gases and 
 of ARGON AND HELIUM. He thinks it probable that they 
 vary as 1 : 2 : 4 according as the molecule contains 1, 2, 4 
 atoms. But he has overlooked the atomic rotations. 
 
 The entire difference between 6,8 (chlorine) and 4,8 
 (oxygen) corresponds to AN INCREASE OF ONLY 16 PER 
 CENT. IN THE DISTANCE between the two atoms of chlorine 
 in its molecule over that of the oxygen atoms. The latter 
 does not dissociate, the former does yield to heat. 
 
 97. ATOMIC LIBRATION. 
 
 1. When Galileo had directed his telescope upon the face 
 of the moon, he recognized slight changes. It seemed that the 
 moon’s face turned a little, like the beam of a balance. He 
 accordingly called the phenomenon the LIBRATION OF THE 
 MOON. It has occupied observers and mathematicians for 
 over a century. 
 
 2. The real home of the balance is the chemical laboratory. 
 THE TRUE LIBRATION IS THAT OF THE ATOMS. It is of 
 more decided importance in molecular mechanics than that of 
 the moon in cosmical mechanics. It is of infinitely greater 
 extent, also. Such ‘’titubazione” in macrocosmos would be 
 destruction. 
 
 3. Are the PHENOMENA OF ATOMIC LIBRATION occult 
 and hard to see.? Oh, no! They are so manifest that they 
 stand boldly out from the tabulated data of boiling points, of 
 fusing points, circular polarization, magnetic rotation, and 
 others. 
 
ATOMIC LIBRATION. 
 
 3C7 
 
 4. What phenomena are here referred to as due to atomic 
 librations? The whole world of TAR-DERIVATIVES is 
 dripping full of them! There is benzol, crystallizing at about 
 the same temperature as does water. Put one chlorine in the 
 place of one of its hydrogen, and down goes the fusing point 
 half-a-hundred degrees. Replace still another atom, and the 
 fusing points jumps up a hundred degrees. Thus it keeps 
 alternating up and down, while the benzol atom is being 
 gradually loaded with chlorine instead of with hydrogen. 
 Here you have the continuity of nature in the chemical pro- 
 cess, and rank discontinuity in the physical result. The 
 chemist moves by continuous steps — and nature jumps like a 
 see -saw! 
 
 5. And in truth, IT IS A SEE-SAW. You balance a plank 
 nicely. A little boy jumps on — down goes his end of the 
 plank. The boy’s playmate manages to get onto the plank 
 and walks to the other end— down that goes, carrying up the 
 first one. Here we have the libration of a plank, produced by 
 two little imps full of fun and mischief. Atomic libration is 
 mechanically produced in the same manner. 
 
 6. Here is a benzol atom (Plate page 395) ; THE FAMOUS 
 BENZOL RING AS IT IS IN REALITY, shown in ground plan 
 or horizontal projection, in accordance with our established 
 atom -linkage. Suppose the hydrogen atom place 1 be 
 exchanged against an atom of bromine. What will happen? 
 
 7. The total benzol weighs 78. The single bromine sub- 
 stitution adds 79 thereto and doubles it. The CENTER OF 
 GRAVITY moves from the center of the ring half way towards 
 place 1. The effect on the moment of inertia for the vertical 
 axis is easily calculated — determining the boiling point. For 
 the axis parallel to the paper, determining the fusing point, 
 the case is a little more complicated. 
 
 8. The old axis — for benzol itself — was parallel to the plane 
 of the projection, and passed through the center of the ring, 
 that being the center of gravity. THE NEW AXIS, for the 
 
368 
 
 LECTURE 97. 
 
 mono-bromide, FORMS QUITE AN ANGLE with that plane, 
 roughly passing through the bromine atom and that center of 
 the ring. Thus the added weight of bromine at distance zero 
 adds almost nothing to the moment of inertia, which has been 
 greatly reduced by the displacement of the center of gravity. 
 
 9. But now add another atom of bromine where it will 
 produce THE GREATEST MECHANICAL EFFECT, that is IN 
 PARA- POSITION, at 4. Since the H or Br at 1 is in the plane 
 of carbons, 2, 4, 6 and the H or Br at 4 in plane with carbons 
 1, 3, 5, the two bromine in para-position (1, 4) balance, 
 restore the center of gravity to the center of the ring. Hence 
 we have their full distance effected in the moment of inertia, 
 which goes up about twice as much as the first depressed it. 
 In the tetra-bromide (1, 4; 2, 5) we have two para-positions ; 
 hence double rise of melting point. In hexa bromide we have 
 three para-positions (1, 4; 2, 5; 3, 6) and hence threefold 
 rise. The change of inclination becomes less as the total 
 weight increases. Hence the rise in fusing point for the 
 second and third para — addition is greater than for the first. 
 
 In the tri- bromide (1, 4; 2) we have the para position 
 (1, 4) added to 2. So also the penta-bromide is one added to 
 the di-para (1, 4; 2, 5). The' diagram for chlorides shows 
 from Benzol the fusing points of the para-compounds at 
 B, D, F (mono-, di-, tri-para) and the depressed monochlorid 
 at A, raised by two paras (mono-, di-)toCandE. Page 395. 
 
 This is the simplest case of atomic libration. Without 
 using a mathematical formula I trust THE PROBLEM IS 
 CLEARLY STATED AND ITS SOLUTION FULLY INDICATED. 
 The plate (p. 395) shows that the case is general, applying 
 to all chloroids. For radicals, the case will be modified by their 
 open structure, as shown long ago. See C. R., T. 115, 
 p. 177; 1892. 
 
 10. It will be understood that these LIBRATIONS AFFECT 
 NEARLY ALL PROPERTIES. Thus the para-compound neces- 
 sarily occupies the greatest volume — as Feitler has found 
 experimentally. Our modern journals are full of facts — for it 
 
ATOMIC LIBRATION. 
 
 3 G 9 
 
 is facts, you know, new observations, “eigene Bestim- 
 mungen,” that our Geheimrathe want — for such things can 
 be manufactured by the students, and be published “in 
 stattlichen Banden.” 
 
 11. The state of my health has not allowed me thus far to 
 publish either of the volumes planned to succeed my True 
 Atomic Weights. The solution here given is, however, broad 
 and complete. ANYONE UNDERSTANDING MECHANICS 
 CAN PUT THE SOLUTION INTO EQUATIONS. It is a simple 
 matter of detail. I will only add, that the case of “odd and 
 even compounds” of alcoholics (Lect. 93) is really also involv- 
 ing an inclination of the axis, especially where the terminal is 
 heavy, and the number of carbons low, as in formic and acetic 
 acids. One of the most interesting cases of atomic libration 
 is presented in the THREE CHLORACETIC ACIDS; however, 
 the calculations are rather intricate. 
 
 12. The Ring- Form of Benzol has been demonstrated by 
 my formulae in 1874 (Principles, p. 120; also C. R., T. 80, 
 p. 47; 1875). The above formula (Lect. 96, 6) for benzol 
 vapors gives I — 70, since S 29.26 observed, and n = 12, the 
 internal work being taken at 3.5 as for alcoholics. If this be 
 less, the moment I will be correspondingly greater. 
 
 But for the six CH forming a straight line, the moment 
 would be at least 227. This is entirely at variance with the 
 above value due to the specific heat. If the center of gravity 
 of the six carbons be at a distance r and those of hydrogen 
 at r, the moment of inertia will be 6. [C.r^ + H.r,^] . 
 Taking, as first approximation r, = r we find r = 0.95. This 
 is very nearly the value 1.00 of our construction, p. 395. 
 
 Note. — In looking through Perkin’s determinations of magnet rota- 
 tions in the closing number for 1896 of the bulky Zeitschrift, I notice a 
 multitude -of the plainest confirmations of these principles. The o 
 much greater than p (p. 633) because ortho have new weights nearest 
 and on opposite sides of the central plane — producing maximal torsion. 
 So a naphtols greater than ft, p. 635. 
 
98. ATOMIC CRYSTALS. 
 
 1. The old Teutons and Scandinavians believed that 
 “Cobolde” and “Nisser” inhabit the caves of the earth, 
 gather metals and skillfully work them into ornaments and 
 weapons which they bestow as gifts on their favorite among 
 women and men. But if man surprises them, these dwarfs 
 suddenly assume the form of beautiful crystals, which there- 
 fore are called QUARTZ (dwarf). See Dedication, 3rd section. 
 
 2. The magnificient quartzes of the Alps were well known 
 to the Romans, for Pliny speaks of them at length (15, 2). 
 They supposed them to arise from celestial vapors and purest 
 snow; but WHY THEY GROW SIX-SIDED, Pliny deems it 
 hard to tell. Quare sexangulis nascitur lateribus non-facile 
 ratio inveniri potest (Hist. Nat. 37, 9). 
 
 3. From celestial vapors forms purest snow indeed — and 
 that SNOW HAS ALSO THE SIX-SIDED FORM. Every-one in 
 northern countries can see these star-like forms if he will but 
 look at the snow lodging on his coat on a dry, cool winter day 
 while snow is falling. A simple magnifier will reveal most of 
 the beauties of these snow -stars. 
 
 4. Though so common and abundant an object, the real 
 six-sided form of the snow -star was not noticed before Kepler, 
 who described them 1611 in a special publication of 24 pages 
 quarto : DE NIVE SEXANGULA. How did it happen that the 
 astronomer Kepler saw what all others had overlooked.? 
 
 5. Kepler’s mind was filled with the PYTHAGOREAN AND 
 PLATONIC IDEAS of geometrical and numerical harmonies in 
 Nature. He had published (1596) his Mysterium Cosmo- 
 graphicum, in which the five regular bodies are made to 
 determine the dimensions of the planetary system. In 1619 
 he finally completed his search for the great laws of the solar 
 world, as published in his Harmonices Mundi. 
 
ATOMIC CRYSTALS. 
 
 371 
 
 6. No wonder that such a man would notice with delight 
 the beautiful and regular forms of the six-sided snow-stars! 
 He even went further and asked: Cur antem sexangula.? 
 This question has remained until 1 showed in my Programme 
 (1867) WHY THE SNOW-STAR IS SIX-SIDED. In the Scien- 
 tific. American for April 18, 1868, this question is fully 
 answered in popular form. 
 
 7. Water is represented by the formula Ha O. Every 
 atom of water consists of three distinct particles, namely, two 
 of hydrogen and one of oxygen. But three equal material 
 points can only remain in stable equilibrium if they are equi- 
 distant, that is, FORM AN EQUILATERAL TRIANGLE. These 
 triangles, aggregating in parallel positions, form a regular six- 
 sided star. This is the actual form of the snow- star. See 
 drawings of Glaisher (below) and the beautiful microphoto- 
 graphs (p. 53) published by Dr. Hellmann (Berlin, 1893). 
 
 ; 
 
 1 V \ / 1 — 1^ 
 
 ♦ 
 
 ■ ffe ^ 
 
 
 8. The formula of quartz is Si O 2 . Its crystal form must, 
 therefore, also be hexagonal. So it is. Even its rotary 
 polarization is accounted for in this way. See my communi- 
 cation UEBER DEN BAU DES QUARZES to the Academy of 
 Sciences of Vienna, presented by Haidinger (Sitzungsberichte, 
 I Abth., Bd. 61; 1870). 
 
372 
 
 LECTURE 98. 
 
 9. This explanation must be supplemented by the determi- 
 nation of THE THIRD DIMENSION or axis. When a liquid 
 crystallizes, its molecules cease to rotate; they aggregate 
 according to the quadratic form inscribed in the cylinder of 
 rotation. See half page (3T) from my Programme der Ato- 
 mechanik 1867, reproduced on page 399 in two-thirds its 
 original dimensions. 
 
 10. This shows the cause of dimorphism (21, 7). At the 
 same time, the constituent atoms, not being equal in the com- 
 pound or crystal-atom, the exact dimensions will be subject 
 to small pertubations depending on the actual atomic weights. 
 These MOLECULAR PERTUBATIONS have been determined 
 in my paper read at the Salem meeting (1869) before the 
 American Association for the Advancement of Science (Pro- 
 ceedings, pp. 100-112). 
 
 11. Even the case of TRIMORPHISM of titanic oxide has 
 been fully considered in 1867 (Programme pp. 32-33). It may 
 be added, that Tridymite is the ice-form of silica, as already 
 published in a circular of August 1868. A very concise, con- 
 nected exposition of this entire subject is given in my 
 PRINCIPLES OF PURE CRYSTALLOGRAPHY, 1871; 44 pp. 
 
 12. THE DETERMINATION OF THE CRYSTAL-AXES 
 from the measurement of the crystal angles is shown in the 
 case of the two forms of sulphur on page 69. It is evident 
 that the inclination Pq gives the ratio of the axes B and C, 
 while the plane angle on P gives the ratio of the axes A and B 
 in native sulphur or sulphur crystallizing from its solution in 
 bisulphide. Lect. 21. 
 
 13. The simple case of sulphur (p. 69) also shows how 
 THE SECONDARY FACES P, q, are related to the primary 
 octahedron O, the dimensions of which are taken as the axes 
 A, B, C. For quartz and calcite, a few of the very numerous 
 secondary faces are shown on plate 65. The plates pp. 56 to 
 64 give reduced copies of eighteen of the excellent plates of v. 
 Kokscharow showing secondary faces of leading crystallized 
 
ATOMIC CRYSTALS. 
 
 373 
 
 minerals. These plates are constantly referred to in crystal 
 description and in our crystal practicum. 
 
 14. The true ORIGIN OF SECONDARY FACES was dis- 
 covered by the crystalloclast, Hauy (see p. 55). A fine 
 calcite prism (Fig. 1) inadvertently dropping from his hands, 
 he found that its cleavage gradually lead to the fundamental 
 rhombohedron of 105 degrees, see Figures 2 to 5; compare 
 Lect. 11, 12. From the scalenohedron he obtained the same 
 cleavage form (Figures G, 7). So he did from all other calcite 
 forms (Fig. 8).. Compare calcite, p. 65. 
 
 15. Accordingly, Hauy considered a minute cleavage 
 rhombohedron THE CRYSTAL-MOLECULE of calcite. By 
 Figure 17 (p. 55) he shows how the scalenohedron is built up 
 from such molecules. On page 392 we copy his synthesis of 
 the dodecahedron and the pyritohedron from minute cubes. 
 In a like manner, all the varied tesseral forms (pages 58, 59) 
 can be built up from minute cubes. 
 
 16. THE MARKINGS OF THE SURFACES often show the 
 reality of this mode of growth of the crystals. The striations 
 of the cubes of pyrite mark the lines of growth of the pyrito- 
 hedron (9, 12). The horizontal stri^ of the prismatic faces 
 of quartz (Lect. 10, 6 and plate 65) mark the edge z r, and 
 really the disc of Si O 2 atoms. It is in French works 
 that nature’s own way, recorded by Hauy, is still properly 
 presented. See Friedel, Mineralogie, Paris, 1893. 
 
 17 . It is only these natural forms and their AXIAL EQUIVA- 
 LENTS OF WEISS, of Berlin, that are fit for use in the study 
 of the origin of crystal forms and dimensions. It gives me 
 sincere pleasure to see that the author of the best crystallo- 
 chemical mannual. Professor C. F. Rammtlsberg of the Uni- 
 versity of Berlin, emphatically expresses the same views and 
 conforms thereto in his admirable Handbuch (First edit., 1855 
 and 1857; second, 1881, 1882). 
 
 18. This mere glance at the origin of the wondrous crystal 
 forms may suitably be closed by a reference to my statistical 
 
374 
 
 LECTURE 98. 
 
 investigations of the relative FREQUENCE OF TFIE FIIGFIER 
 FORMS OF SYMMETRY, presented for me to the Academy of 
 Sciences by the profound Haidinger (Sitzungsberichte, Abth. 
 1, Bd. 62; 1870). I find the higher forms of symmetry 
 excessively predominant in nature. The probability of a 
 tesseral form is many million times that of any given triclinic 
 form. 
 
 19. A few of the points established by me almost thirty 
 years ago and published in the Sitzungsberichte of the 
 Academy of Sciences, of Vienna, have recently found their 
 way into the great Leipzig Organ of Ostwald— of course as a 
 new discovery (Retgers). 
 
 20. This reminds me that James D. Dana, after having 
 studied my paper, which was for months (1867) in his poses- 
 sion, made a complete scientific somersault in the July and 
 September numbers of his Journal for 1867. Since my 
 Atomechanik had appeared in June, he was compelled to 
 admit priority of publication, but brazenly claimed “inde- 
 pendent thought in independent minds.” It is remarkable 
 that the mind of Dana did not reach the third dimension, but 
 only my law of symmetry in the one plane. It so happened 
 that this part was the only one in his hands. Flence his inde- 
 pendent editorial mind could not proceed for lack of copy. 
 Servility bows to position and power; but honor and truth will 
 prevail in the end. 
 
 SUPPLEMENT TO ATLAS. 
 
 But few of the instruments intended to be shown were left in each 
 group, which still shows some overlapping and thus may call for verbal 
 explanation. Space demands limitation to the most remarkable case, 
 the compound blowpipe on page 38S. The Kipp produces the oxygen 
 (p. 170). This is probably the simplest possible manner of showing the 
 Tuagnificient shower of sparks from burning watch springs and the 
 dropping of molten platinum from a good sized wire. Instead of illumi- 
 nating gas here used, another Kipp will furnish the hydrogen gas, and 
 complete the outfit. The compound jet must have fine perforations and 
 be nicely adjustable. I use a jet taken from a calcium light outfit for 
 compound gases. 
 
99. ATOMIC WEIGHT. 
 
 1. The smallest particle of matter entering into chemical 
 combination with any other such particle, is called a CHEMI- 
 CAL ATOM. Its weight is called the atomic weight of the 
 substance concerned, expressed in any convenient unit of 
 weight. The methods used and results obtained in the 
 determination of the atomic weights of the elements have 
 been given (Lect. 40). 
 
 2. Dalton introduced this idea into chemistry, about a 
 century ago (Lect. 40, Note). His TABLE OF ATOMIC 
 WEIGHTS was small, but remarkably good for a first attempt. 
 Both his law of combination and the real values of the atomic 
 weights received their experimental demonstration at the 
 hands of that great chemist who for a life time was without 
 a peer — Berzelius, of Sweden (p. 22). 
 
 3. BERZELIUS devised the most exact methods of analysis 
 and applied these methods during forty years to the determi- 
 nation of the atomic weights of the elements, several of which 
 he himself discovered (Se, Si, Th, Va). The first connected 
 exposition of his results are given in his Essay sur la theorie 
 des proportions chimiques, Paris, 1819. This work also forms 
 part of his elements of chemistry, which for a quarter of a 
 century remained the textbook of the chemical world. 
 
 4. In 1840, DUMAS (p. 25) began his fundamental work 
 on atomic weights, determining that of carbon and of hydro- 
 gen in reference to oxygen (Lect. 31, 3 — 8). The atomic 
 weight of oxygen being taken at 16, that of hydrogen is 1, 
 that of carbon (diamond) is 12, exactly. His work has unjustly 
 been drawn in question. He also made admirable determi- 
 nations on silver in the dry way (21, 10). 
 
 5. STAS (p. 33) was permitted to assist Dumas in his 
 combustion of the diamond. He made many determinations 
 at Brussels, on silver and its nitrate, sulphate and sulphide, 
 and especially in the wet way with chlorine, bromine and 
 
370 
 
 LECTURE 09. 
 
 iodine. He knew to .surround his results with a halo of 
 excessive accuracy in the form of mathematical calculations; 
 but since his atomic weights vary with the amount operated 
 upon, the accuracy assumed is nol real. 
 
 6. Since Hofmann of Berlin made chemical patents so 
 popular among German chemists, the latter have added 
 scarcely anything to this field of science, beyond the most 
 extravagant endorsement of the perfection and accuracy of the 
 results of Stas. To question the absolute reliability of the 
 values of Stas— and of his philosophical conclusions — is 
 generally taken in the Fatherland as a sign of inferioity. 
 
 7. As a glaring specimen, I have printed a complete trans- 
 lation of the ENDORSEMENT OF STAS by the editor of the 
 Jahresbericht and his thirteen paid aids. See my True 
 Atomic Weights, p. 37 — 38; 1894. The absurdity of the 
 style and language of this document, and the evident lack of 
 understanding of the subject, makes it one of the most charac- 
 teristic documents of modern chemistry. 
 
 8. STAS AND HIS SCHOOL BELIEVE they have demon- 
 strated that THE ATOMIC WEIGHTS OF THE ELEMENTS 
 ARE NOT EXACT MULTIPLES of half the atomic weight of 
 hydrogen. Stas and his school therefore consider it experi- 
 mentally demonstrated that the chemical elements cannot be 
 taken as compounds of one single material or substance. 
 
 9. In the work of mine just referred to (256 pp. with many 
 plates) I have critically examined both the chemical work and 
 the mathematical reductions thereof. My result has been 
 that BOTH THE CHEMICAL WORK AND THE MATHE- 
 MATICAL REDUCTIONS THEREOF are entirely unworthy of 
 the consideration in which they are held, a consideration due 
 to lack of real critical study. 
 
 10. The chemical work of Stas does not comply with the 
 first condition of all chemical analysis, that its results must be 
 independent of the amount operated upon. IT IS ABSURD to 
 suppose that the atomic weight of silver can vary according 
 as it is part of 10 grammes, 100 grammes or 400 grammes. 
 
ATOMIC WEIGHT. 
 
 377 
 
 The Stasians say, these differences are small ; true, but they 
 are of the very magnitude on which the conclusion they draw 
 depends for support. See plate, page 79. 
 
 11. THE MATHEMATICAL REDUCTIONS of the Stasian 
 school (made by Ostwald, Karl Seubert, Lothar Meyer of 
 Germany, Thomsen of Denmark, Sebelien of Norway, Van 
 der Plaats of Holland, F. W. Clarke of the United States) is 
 something really astonishing. It would be decidedly amusing, 
 if the errors which this school supports by its spurious science 
 were not so serious in their consequences. 
 
 12. I do not need to enter upon details in this place. I 
 may refer to my book, THE TRUE ATOMIC WEIGHTS of the 
 Chemical Elements and the Unity of Matter, St. Louis, Mo., 
 U. S., 1894. The main topics of this work were first 
 published in the Comptes Rendus of the Academy of Sciences 
 of Paris, in volumes 115 to 118 (1892 — 1894), thanks to the 
 kindness of Berthelot. 
 
 13. Not only the entire method of reduction used at 
 present is faulty, but our chemists employ a sort of FLOAT- 
 ING BUOY INSTEAD OF FIXED, IMMOVABLE MARK. It is 
 incredible, but true. Hence they never can tell where they 
 are. See Comptes Rendus, T. 116, p. 695; 1893. The 
 proper method to be used is also presented in that article. 
 
 14. Furthermore, it is necessary to adopt the most perma- 
 nent and definite element as the STANDARD OF MATTER for 
 the system of atomic weights. THE DIAMOND is the only 
 elementary substance that can be used. For details see 
 Comptes Rendus, T. 117, p. 1075; 1893. Also True Atomic 
 Weights, p. 174. The system of weights so resulting is 
 represented on page 398. 
 
 15. Publications of the Smithsonian Institution and the 
 position of our government chemists are strongly Stasian. So 
 is the work of the young chemist at Harvard and that of 
 Professor Morley, whose work for years has been assisted by 
 funds of the American Association . for the Advancement of 
 Science. They ought to be satisfied with the overwhelming 
 
378 
 
 LECTURE 99. 
 
 majority and not suppress an individual dissenter. It is just 
 barely possible that nature alone decides. 
 
 16. While our Stasian’s rejoice in the results of Morley 
 and applaud his presidential address at Buffalo (August, 1896), 
 we hear from Leduc of Paris (C. R., T. 123, p. 807; 1896) 
 that the weight, in grammes, of a litre of oxygen is 1.4293, 
 of nitrogen 1.2507. Now one-sixteenth of the first is 
 0.08933 and one-fourteenth of the latter is 0.089335. THESE 
 ATOMIC WEIGHTS ARE CERTAINLY COMMENSURABLE. 
 
 17. The value of this quotient should agree with the 
 weight of a liter of hydrogen gas, see page 196. THE 
 WEIGHINGS OF HYDROGEN made are 0.0898 or about half 
 a milligramme in excess per liter. Of course, our experi- 
 menters, especially Professor Morley, could not commit such 
 an error. His hydrogen, he says, was pure. And yet, it is a 
 fact, that for a century our experimenters overlooked THAT 
 LITTLE ONE PER CENT. OF ARGON in the air, and relied on 
 the false weight of nitrogen until Lord Rayleigh discovered 
 this source of error! 
 
 18. I cannot close this lecture without mentioning two of 
 our younger American chemists working in this line — Professor 
 RICHARDS at Harvard, and Professor EDGAR F. SMITH at 
 Philadelphia. The former — a dyed in the wool Stasian — 
 recently found Mg 24.5, by starting with something he does 
 not know what, and ending with something he knows as well. 
 This result represents an error of over two per hundred on the 
 value Mg 24. I am not competing in this work; but my 
 gasometric work proves that the fine work done at Harvard is 
 altogether too fine. A little error of two per cent, in the 
 atomic weight of an element used in many quantitative 
 determinations (phosphate, etc.) is really a tangible and 
 substantial achievement for Old Harvard. 
 
 In the Laboratory of the University of Pennsylvania, atomic 
 weight determinations are also made. 1 have been delighted 
 with the evidence that Professor Smith deems is as necessary 
 to weigh known substances as BERZELIUS did. 
 
100. ALCHEMY AND ELEMENT. 
 
 1. The researches of Berthelot in THE EARLY HISTORY 
 OF CHEMISTRY are as important as they have been extended 
 (see pages 42, 43). An outline of his labors we have 
 in the elegant edition (Paris, 1885) of his fascinating work: 
 Les Origines de I’Alchimie. His later works have been on a 
 large scale every way. 
 
 2. Berthelot has strongly accentuated the kinship of 
 thought between the alchemist and the modern chemist in 
 reference to THE CONSTITUTION OF MATTER. What 
 sounded strange forty years ago to prominent men in letters 
 of mine, and thirty years ago in my Programme (1867) is 
 now tacitly admitted. 
 
 3. Says Professor Schiitzenberger in his introduction to 
 the lecture on my True Atomic Weight: “To him (i. e. 
 Hinrichs), and we may say, somewhat to all of us, the 
 elements of which the material world is composed, are the 
 result of the condensation, according to certain laws, of a 
 single principle, which he (Hinrichs) calls PANTOGEN.” 
 Actualites, p. 4; 1896. See dedication, last clause. 
 
 4. This is not the place nor the time for a historic expo- 
 sition of ATOM MECHANICS; but we may state, that by 
 publications and by letters received we could easily show that 
 this change has been mainly due to our own work, a notable 
 part of which is still credited to those who merely appropriated 
 it surreptitiously, as did Naumann, Dana, Lothar Meyer and 
 a few others. 
 
 5. This implies that many of the Stasians do not believe 
 in their own statements. It is palpably impossible to admit 
 the Stasian Atomic Weights and at at the same time conceive 
 the elements to be compounds of some primitive matter or 
 perhaps a few such materials (if that were not almost equally 
 self-contradictory) . 
 
380 
 
 LECTURE 100. 
 
 6. Now, we have shown the Stasian Atomic Weights to be 
 erroneous to a much greater extent than necessary to destroy 
 their value as an argument for the complexity of the elements. 
 We have found all well established atomic weights multiples 
 of one twenty-fourth of that of carbon, correspondingly to half 
 the atomic weight of hydrogen. True Atomic Weights, 
 p. 208—213. 
 
 7. As to constitution, the elements may be divided into 
 three systems, namely THE HYDROGEN, CARBON AND 
 IRON SYSTEMS. The last two are very comprehensive. 
 They vary in two ways, in valence and in weight. We shall 
 consider each of these variations separately. 
 
 8. Let us start with the monad carbon, C = 12; and see 
 how it varies in weight. First by simple increase in length, 
 the weight a and 2a added gives a heavy and a light dyad. 
 See plate, page 80. Here a is 16. Hence the heavy dyad 
 is Si 28 and the light dyad — ? 44. These combinations corre- 
 spond to binary compounds of elements. 
 
 9. Either of these dyads next combines with three, and six 
 and twice six a, like ternaries (nitrates, chlorates) but under 
 more or less previous surrender of weight to secure complete 
 combination — as H has to be surrendered to make hydrocar- 
 bons combine. In the carbon group we have instead of 
 3 A = 48 and 6 a = 96, only 45 and 89, leaving 3 and 7 for 
 the tie holding the a together around the dyads. 
 
 10. THE CHANGE IN VALENCE is combined with a change 
 in electrical character. Carbon has the valence 4 and is 
 about equally positive and negative. Increase of matter 
 makes it negative and decrease makes it positive. Thus: 
 12 4- 2 = 14 = N, 12 -f 4 := 16 = O and 12 -h 7 = 19 = FI 
 are increasingly negative and of valence 3, 2, 1 respectively. 
 So 12 — 1 = 11 = Bo, and substraction of 2 more gives suc- 
 cessively 9 = Be and 7 = Li, the positive elements of 
 valence 3, 2, 1. 
 
 11. Between the positive and negative valence One we 
 have long suspected a VALENCE ZERO; our general formula of 
 
ALCHEMY AND ELEMENT. 
 
 381 
 
 1874 (Principles, page 180, 181) and comparison to hydro- 
 carbons paralleled, shows this. This group of elements evi- 
 dently is represented by argon and helium. For a = 2 (10 — n) 
 gives for the valence n = o, a = 20. We will not now 
 further enlarge on the production of positive and negative 
 electric character by removal and addition of matter to the 
 carbon. See diagram at upper right hand of Plate 80. 
 
 12. The iron system corresponds exactly hereto, except 
 that ITS ELECTRICAL CHARACTER IS REVERSED, that is, 
 becomes negative by substraction of matter. This is already 
 strongly marked in my Programme (1867) in the reversal of 
 the spiral, § 37, p. 9 (see Plate 396) specified in § 54, p. 10. 
 
 13. The diagram, Plate 397, gives an ideally complete 
 view of THE COMPOSITION OF THE ELEMENTS. The car- 
 bon system (C 12, smaller disks) starts near the center 
 (pantogen) and divides into light (open) and heavy (full 
 disks). The iron system starts farther from the center 
 (Fe = 56, larger disks). The Argonoids and Adamantoids are 
 opposite extremes, joined by the 1, 2, 3 atomic negatives and 
 positives in upper and lower half of diagram. 
 
 14. There is of course no such a thing as a real PERIODIC 
 SYSTEM of the elements — consecutive spires of eight elements 
 each, increasing the atomic weight by sixteen for each spire. 
 This is nothing but a hasty generalization from my Atome- 
 chanik of 1867 on the part of Lothar Meyer. He reviewed my 
 book, condemned it; then published his periodic law. See 
 how MendelejefPs is only a reflection of mine, top figure, page 
 398 where A-B represents a vertical, plane mirror. Details^ 
 True Atomic Weights, pp., 227-255. 
 
 15. All about the valencies is given in my Programme 
 (1867, p. 11-17), where also diagram of valencies is given on 
 page 15, here reprinted, page 385. The wall chart (p. 391) 
 has hung for twenty years in my lecture hall in Darkest 
 America; it is the above (plate 396) more carefully drawn. 
 Adapted to letter press, we used diagrams p. 73. Look at that 
 in a mirror, you have the so-called Mendelejef’s, see p. 398» 
 
382 
 
 LECTURE 100. 
 
 16. The constititution here given makes it most probable, 
 that when intensely heated in a properly resistent autoclave, 
 DOUBLE DECOMPOSITIONS OF THE ELEMENTS may be 
 produced (True Atomic Weights, p. 224). 
 
 Most assuredly, THE CENTRAL PARTS OF THE EARTH 
 consist mainly of the heaviest metals (Au, Pt). The specific 
 gravity of the nucleus must be at least 16 (Plana); hence 
 must consist mainly of these and kindred metals. The physi- 
 cal and chemical properties of the elements are functions of 
 the form and weight of their atoms. 
 
 17. At the close of this hasty glance at the chemical 
 composition of the elements, we thus come to ADOPT THE 
 OPINION OF THE ANCIENTS that it is not impossible to con- 
 vert one element into another, or in the language of the 
 Ancients, to make gold. Hence we have placed the Chryso- 
 poeia of Cleopatra (Berthelot) at the top of page 385 above 
 our old system of valence. Also the Ouroborus on the first 
 page of this book and here at its close. 
 
 18. The element atoms are different compounds from those 
 of compound atoms; for in the first the constituent atoms or 
 pantogen atoms are rigidly united, admitting not even of 
 separate vibrations (96, 11). It will accordingly require AN 
 IMMENSE AMOUNT OF ENERGY to effect their decomposition. 
 But whether that is soon effected or not, I think it is now 
 evident that all matter is One which we call Pantogen, 
 .and that the Ancients were right in saying: EN TO nAN. 
 
Hinrichs’ 
 
 Contributions to Atom-Mechanics. 
 
 PUBLISHED IN THE COMPTES RENDUS OF THE 
 ACADEMY OF SCIENCES OF PARIS. 
 
 FIRST SERIES. 
 
 GENERAL MECHANICS OF THE THREE STATES OF 
 AGGREGATION. 
 
 1873: Tome 76, p. 1357; p. 1408; p. 1592. 
 
 1875: Tome 80, p. 47; p. 565; p. 766. 
 
 SECOND SERIES. 
 
 THE GENERAL RELATIONS BETWEEN BOILING POINT, 
 PRESSURE AND ATOMIC WEIGHT AND 
 FORM OF COMPOUNDS. 
 
 1891: Tome 112, p. 998; p. 1127; p. 1436. 
 
 1891: Tome 113, p. 36; p. 313; p. 468; p. 500; p. 743, 
 p. 798. 
 
 THIRD SERIES. 
 
 THE GENERAL MECHANICAL EFFECTS OF CHEMICAL 
 SUBSTITUTION. 
 
 1892: Tome 114; p. 597; p. 1015; p. 1064; p. 1113; p. 
 1272; p. 1367. 
 
 1892: Tome 115, p. 177; p. 239; p. 314. 
 
 FOURTH SERIES. 
 
 DETERMINATION OF THE TRUE ATOMIC WEIGHT OF 
 THE ELEMENTS. 
 
 1892: Tome 115, p. 1074. 
 
 1893: Tome 116, p. 431; p. 695; p. 753. 
 
 1893: Tome 117, p. 663; p. 1075. 
 
 1894: Tome 118, p. 528. 
 
 A reference list to the author’s contributions to Cosmical 
 Science, Meteorology and Technical Chemistry has been pub- 
 lished elsewhere. The work in Meteorology has been quite 
 voluminous. 
 
HINRICHS’ 
 
 SEPARATE WORKS ON ATOM-MECHANICS. 
 
 PROGRAMME DER ATOM-MECHANIK, Oder, die Chemie eine 
 Mechanik der Pan-Atome. — 44 pp. 4®, Iowa City, Iowa, 
 1867. French Resume of same, 4 pp. 4®, November 
 1867. English Resume, 4 pp. 4^ August 1867. 
 
 THE PRINCIPLES OF PURE CRYSTALLOGRAPHY.— pp. IV, 
 44, in 8®, Davenport, 1871. See especially. Chapter VI. 
 
 THE METHOD OF QUANTITATIVE INDUCTION IN PHYSI- 
 CAL SCIENCE.— Davenport, 1872. See especially the 
 last section, p. 36, giving the Mechanics of the three 
 States of Aggregation. 
 
 THE PRINCIPLES OF CHEMISTRY AND MOLECULAR 
 Mechanics . — 200 pp., 8®, with two plates. Cloth. 
 Davenport and New York, 1874. 
 
 BEITRAEGE ZUR DYNAMIK DES CHEMISCHEN MOLE- 
 KUELS. — Leipzig, Gustav Fock, 1892: 
 
 I. — The Molecule as a System of Material Points. II. — The Energy 
 of the Molecule. III. — Graphical Structural Fprmulae. IV. — The 
 Moments of Inertia of the Molecules. VI. — The Boiling Points of 
 Isomeric Bodies Determined by the Moment of Inertia of the 
 Molecules. 
 
 The above Beitraege will be sent by the undersigned on receipt 
 of 50 cents. 
 
 These Beitraege were sent to A. W. Hofmann for the Deutsche 
 CiiEMiscHE Gesellsehaft (I, II, April, 1872; III — VI, April, 1873), of 
 which the author was a Foreign Member. 
 
 No one at Berlin did understand these papers. This very interesting 
 and characteristic episode in the history of Atom-Mechanics is con- 
 tained in the above edition of 1892. 
 
 THE TRUE ATOMIC WEIGHTS of the Chemical Elements 
 and the Unity of Matter. With Plates and Diagrams. 
 St. Louis: Carl Gustav Hinrichs, Publisher. B. Wester- 
 mans & Co., New York. 1894. XVI and 256 pp. 8 vo. 
 Will be sent prepaid to any part of the Postal Union upon 
 receipt of price ($3.00) by the publisher. 
 
 Address CARL GUSTAV HINRICHS, Publisher, 
 
 ST. LOUIS, MO., U. S. A. 
 
CLEOPATRA’S CHRYSOPOEIA (Berthelot). 
 
 THE STUDENTS ATLAS, 
 
 V. Supplement. 
 
 CHEMICAL VALENCE, HINRICHS, 1867. 
 
 ATOMECHANIK, P. 15. 
 
 385 
 
38G 
 
 WEIGHT AND MEASURE. 
 
887 
 
 GASOMETRIC APPARATUS, 
 
38S 
 
 GAS MANIPULATION. 
 
DISTILLING AND EXTRACTION APPARATUS. 
 
 PROFESSOR’S STAND IN THE CHEMICAL LABORATORY, 
 ST. LOUIS COLLEGE OF PHARMACY. 
 
 889 
 
MICROGRAPHS OF FERMENTS. 
 
 LECTURE 71. 
 
 SACCHAROMYCES— 
 -CEREVISI/£, YOUNG. 
 
 OLD. 
 
 BACILLUS— 
 -ACETICUS. 
 -ACIDI LACTICI. 
 
 890 
 
HINRICHS. THE ELEMENTS. 1867. 
 
 WALL CHART. 
 
 891 
 
THE DODECAHEDRON. 
 
 THE PYRITOHEDRON 
 
 HAUY, ORIGIN OF SECONDARY FORMS. 
 
 392 
 

 
 
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 .398 
 
894 
 
BENZOL. 
 
 395 
 
ATOMECHANIK, P. 9. 
 
 896 
 
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 397 
 
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 X 
 
 ORIGIN OF THE “ PERIODIC LAW.” 
 
 398 
 
HALF OF PAGE 34 FROM 
 
 HINRICHS’ PROGRAMME DER ATOMECHANIK, 1867. 
 
 399 
 
400 
 
 A LOOK-OUT TO THE OLD PASTURES (67, I). 
 
 Lunden was the chief town of North Ditmarsia, the little Republic between Eyder, Elbe and North Sea that maintained 
 its independence for centuries, and kept itself free from all feudal institutions.