THE LIBRARY 
 
 OF 
 
 THE UNIVERSITY 
 OF CALIFORNIA 
 
 Education 
 
 IN MEMORY OF 
 
 Professor 
 
 George D Louderback 
 1874-1957 
 
BEGINNERS' HAND-BOOK 
 
 OF 
 
 CHEMISTRY. 
 
 THE SUBJECT 
 
 DEVELOPED BY FACTS AND PRINCIPLES DRAWN CHIEFLY 
 FROM THE NON-METALS. 
 
 BY 
 
 JOHN HOWARD APPLETON, A.M., 
 
 Professor of Chemistry in Brown University^ 
 AUTHOR OF 
 
 THE YOUNG CHEMIST," "QUALITATIVE CHEMICAL ANALYSIS," "QUANTITATIVE 
 CHEMICAL ANALYSIS," "THE LABORATORY YEAR-BOOK." 
 
 NEW YORK: 
 
 CHAUTAUQUA PRESS, 
 
 C. L. 3. G; DEPARTMENT, 805 BROADWAY. 
 
 1888. 
 
"V^OFJK^ 0|S j^HEMI^TRY 
 
 BY 
 
 PROFESSOR APPLETON. 
 
 I. The Young Chemist. A book of Chemical experiments for be- 
 ginners in Chemistry. It is composed almost entirely of experiments, 
 those being chosen that may be performed with very simple apparatus. 
 
 II.. Qualitative Analysis. A brief but thorough manual for labora- 
 tory use. 
 
 It gives full explanations and many chemical equations. The processes 
 of analysis are clearly stated, and the whole subject is handled in a manner 
 that has been highly commended. 
 
 III. Quantitative Analysis. The treatment of the subject is such as 
 to afford an acquaintance with the best methods of determining all the 
 principal elements, as well as with the most important type-processes both 
 of gravimetric and volumetric analysis. 
 
 THE EXPLANATIONS ARE DIRECT AND CLEAR, so that a pupil is enabled 
 to work intelligently even without the constant guidance of the teacher. 
 By this means the book is adapted for self-instruction of teachers and 
 others who require this kind of help to enable them to advance beyond 
 their present attainments. 
 
 IV. The Laboratory Year-Book. An annual publication contain- 
 ing many convenient tables for laboratory use. New tables are constantly 
 introduced, and changes are made in^rder to keep the matter abreast of 
 the latest discoveries. 
 
 GIFT 
 
 Copyright, 1884, by JOHN HOWARD APPLETON. 
 
$230 
 
 PREFACE. 
 
 |HIS book has been prepared as a popular intro- 
 duction to the study of chemistry. 
 
 It is probably needless to recommend the sub- 
 ject. Chemistry is recognized as a science of such 
 general interest, such wide usefulness, and such universal 
 application, that no intelligent person can endure long to 
 remain ignorant of its principal facts and laws. 
 
 This book treats principally of the non-metals; it is believed 
 to be the verdict of authors and teachers of experience that 
 these furnish the most suitable material for a beginner in the 
 study of chemistry ; these best present the fundamental facts 
 and principles of the science, and they do it in connection 
 with objects and phenomena easily accessible to almost every 
 civilized human being. 
 
 The author contemplates the preparation hereafter of a 
 book of similar general character, only having its principal 
 facts drawn from the chemistry of the metals. 
 
 In writing this book it has been the effort to treat the 
 subject in a style that shall be attractive to the general reader ; 
 but it is believed that in no case has scientific fact been sacri- 
 ficed in the interest of popular form. 
 
 The arrangement of matter in the book is in accordance 
 with the following plan : After the introductory chapters, 
 which present the general principles of chemical action, the 
 chief non-metals are treated in a scientific order as follows : the 
 monads, hydrogen, chlorine, bromine, iodine, and fluorine; 
 
 980 
 
PREFACE. 
 
 then the dyads, oxygen and sulphur; next the triads, boron, 
 nitrogen, phosphorus; finally the tetrads, carbon and silicon; 
 thus including the four great groups into which the non- 
 metals are naturally arranged. 
 
 The historical and biographical sketches, that are distrib- 
 uted through the book, have been introduced with the view 
 of legitimately helping to retain the reader's attention. Most 
 of the experiments described are such as may be performed 
 by any one possessed of reasonable skill ; it is believed that 
 they will afford profitable instruction as well as entertain- 
 ment. Allusions to the applications of chemistry to the affairs 
 of every-day life have been carefully introduced, and have 
 been developed as fully as the circumstances seem to 
 warrant. 
 
 Perhaps it is not improper to make allusion to the read- 
 ing references found at the end of nearly every chapter. 
 They are largely from periodical publications, and it is 
 thought that they will be of service, especially to mature 
 students. Guides to reading are now viewed as among the 
 most important helps offered by teachers to students. The 
 reading lists in this book point out some papers which are 
 selected as being chiefly popular in style ; if these lead the 
 reader to consult the others he will find himself introduced 
 to some of the most important contributions to the knowledge 
 of our science. 
 
 The present edition differs from the preceding one in the 
 addition of several new chapters. Throughout the book also 
 newly-discovered facts have been introduced in their proper 
 places. 
 
 BROWN UNIVERSITY, 1888. 
 
CONTENTS. 
 
 CHAPTER I. P* 
 
 BRANCHES OP NATURAL SCIENCE. The General Term Science. Scientific 
 
 Treatment of a Subject. Province of Chemistry 7-9 
 
 CHAPTER II. 
 
 THE SCOPE OP CHEMISTRY. The Great Number of Different Substances in 
 
 the Earth. How it Happened that there is such a variety 10-13 
 
 CHAPTER III. 
 THE ELEMENTARY SUBSTANCES. List. Comments on it 14-19 
 
 CHAPTER IV. 
 
 NAMES AND SYMBOLS OF ELEMENTS. A Few Principles of Chemical Lan- 
 guage. Names of Elements. Symbols for Atoms 20-25 
 
 CHAPTER V. 
 CLASSIFICATION OF THE ELEMENTARY SUBSTANCES. Metals and uon-Metals. . 26-28 
 
 CHAPTER VI. 
 COMPOUND SUBSTANCES. Binary Compounds. Ternary Compounds 29-34 
 
 CHAPTER VII. 
 THE CONSTRUCTION OF SUBSTANCES. Mass, Molecule, Atom 85-40 
 
 CHAPTER VIII. 
 
 How CHEMICAL AFFINITY WORKS. Each Atom has its Peculiar Affinities. 
 Chemical Affinity Acts Only Under Favorable Conditions. Each Atom 
 has certain General and Special Numerical Preferences. Chemical Changes 
 Neither Create nor Destroy Matter. Chemical Changes Produce Striking 
 Results. Chemical Changes are often Attended by Displays of Force. 
 The Modern Atomic Theory, that of Dalton : 41-53 
 
 CHAPTER IX. 
 
 HYDROGEN. Where Found. Its Discovery. Why not Discovered Earlier. 
 How Prepared ; Four Methods. Powers and Properties Manifested by it. 
 Its Uses. 58-67 
 
 CHAPTER X. 
 
 BALLOONS. Their Invention. The First Ascension. Recent Use of Bal- 
 loons. The Centenary of Ballooning 68-78 
 
 CHAPTER XI. 
 
 CHLORINE. Its Distribution. Its Discovery. Its Preparation. Its Character- 
 istics. Hydrochloric Acid. Bleaching-Powder 79-92 
 
 CHAPTER XII. 
 BROMINE. Its Discovery. Its Preparation. Its Chemical Properties. Its 
 
 Uses 93 ~ 97 
 
 CHAPTER XIII. 
 
 IODINE. Its Distribution. The Old Soda Industry. The Leblanc Process. 
 
 Discovery of Iodine. Chemical Properties of Iodine 98-104 
 
CONTENTS. 
 
 CHAPTER XIV. PAGE. 
 
 FLUORINE. Its Recent Isolation. Its Properties. Hydrofluoric Acid 105-109 
 
 CHAPTER XV. 
 
 OXYGEN. Its Importance. Its Discovery. Its Preparation ; Two Methods. 
 Its Properties. Ozone. Allotropism. Water. Hydrogen Dioxide. Nas- 
 cent State. The Compound Blowpipe. The Calcium Light. Oxygen as 
 Related to Combustions, and to Animal Respiration 110-130 
 
 CHAPTER XVI. 
 
 WATER. Its Abundance. Its Importance to Living Beings. Terrestrial Cir- 
 culation of Water. Water in the Solid Form. Its Influence on Climate. 
 Its Action as a Working Contrivance. Kinds of Water 131-143 
 
 CHAPTER XVII. 
 
 SULPHUR. Its Natural Sources. Its Purification. Its Compounds: Sulphu- 
 retted Hydrogen, Sulphur Dioxide and others 144-154 
 
 CHAPTER XVIII. 
 SULPHUR TRIOXIDE. Sulphuric Acid, its History, Uses, Manufacture 155-160 
 
 CHAPTER XIX. 
 BORON. Borax and its Manufacture 161-165 
 
 CHAPTER XX. 
 
 NITROGEN. Its Discovery. Its Preparation. Its Properties. Compounds of 
 Nitrogen and Hydrogen : Hydrazine, Ammonia Gas and its Properties. 
 Compounds of Nitrogen and Oxygen : Nitric Acid 166-176 
 
 CHAPTER XXI. 
 
 THE ATMOSPHERE. Its Weight. Its Composition. Offices of its Several Chief 
 Constituents. Air Not a Chemical Compound. Fitness of the Air for its 
 Purposes 177-183 
 
 CHAPTER XXII. 
 
 EXPLOSIVES. Gunpowder. Fireworks. Fulminates. Gun-cotton. Nitro- 
 
 glycerin. Dynamite 184-194 
 
 CHAPTER XXIII. 
 
 PHOSPHORUS. Its Sources. Its Agricultural Use. Its Preparation. Its 
 
 Chemical Properties. Friction Matches 195-206 
 
 CHAPTER XXIV. 
 
 CARBON. Charcoal. Animal Charcoal. Lamp-black. Coal. Graphite. The 
 Diamond. Inf usibility of Carbon. Decolorizing Power of Carbon. Other 
 Natural Forms of Carbon. Carbon in Animal and Vegetable Substances. . 207-225 
 
 CHAPTER XXV. 
 
 COMPOUNDS OP CARBON AND OXYGEN. Carbon Monoxide. Carbon Dioxide. 
 
 Effervescing Beverages 226-231 
 
 CHAPTER XXVI. 
 
 ORGANIC CHEMISTRY. Definition. Great Number of Organic Compounds. 
 Organic Compounds Classified : the Fatty Series ; the Aromatic Series : 
 Other Vegetable Matters ; Other Animal Matters . . 232-243 
 
 CHAPTER XXVII. 
 
 ILLUMINATING GAS. The Apparatus Used. The Operation of it Chemically 
 
 Considered. The Various Products . 244-250 
 
 CHAPTER XXVIII. 
 SILICON. Its Quantity in the Earth. Silicic Oxide 251-254 
 
CHEMISTRY. 
 
 I. 
 
 BRANCHES OF NATURAL SCIENCE. 
 
 [HEMISTRY is properly classified as one of the nat- 
 ural sciences. The reader will doubtless inquire, 
 What are the other sciences, and what relation 
 does chemistry bear to them? A suitable answer 
 to these questions will go far toward affording a compre- 
 hensive view of the natural sciences in general, and also a 
 definition of the one with which this book deals. 
 
 The general term "science," originally meaning knowl- 
 edge, at the present day means knowledge that has been 
 thoroughly arranged and classified. 
 
 In the light of this definition it is plain that there are 
 many more sciences than is ordinarily supposed; and not 
 only so, but that science in its widest and most appropriate 
 signification may apply to existences that are not material 
 as well as to the various forms of matter. 
 
 Any subject, therefore, is raised to the rank of a science 
 when the knowledge about that subject is placed in a prop- 
 erly classified form that is, brought under scientific treat- 
 ment. 
 
 Scientific treatment has been defined as the treatment of a 
 subject in accordance with certain thorough and rational 
 methods, involving at least the following particulars: 
 
 First. All possible facts relating to the subject must be 
 observed with the highest degree of exactness. 
 
CHEMISTRY. 
 
 Second. The facts observed must be recorded or described 
 with a fixed unambiguous nomenclature. 
 
 Third. The facts must be arranged in order, the chief 
 facts preceding those that are properly subordinate, the 
 arrangement being carefully studied, and harmonizing as far 
 as possible with the natural relations existing between 
 them. 
 
 Fourth. The facts must be bound together, and their asso- 
 ciation with each other must be displayed by a ration.-d and 
 intelligible explanation. 
 
 When viewed as here presented it becomes evident that 
 the term science is of very wide application, while it is true 
 that in ordinary e very-day use of language the highly gen- 
 eral term science is often applied to natural science; but 
 natural science includes one group of a wide series of groups 
 of subjects. 
 
 The term natural science, then, is properly applied to the 
 knowledge of external and material things, and even then it 
 is properly subdivided according to the kingdom of nature, 
 or according to the special portion of nature's great field 
 with which for the moment it deals. 
 
 In this way two great departments of natural science are 
 recognized : the one called natural history, in which are 
 included geology, zoology, and botany ; the. other called 
 natural philosophy, or oftener physical science, in which are 
 placed mechanics, physics proper, and chemistry. 
 
 Chemistry treats of matter in its deepest recesses and its 
 smallest subdivisions that is, it treats of the atoms of matter, 
 and the changes of properties which even vast quantities of 
 matter undergo by reason of changes in kind, in number, and 
 in relative position of the atoms which, in obedience to chem- 
 ical affinity, are gathered together into minute groups called 
 molecules. 
 
 Undoubtedly the beginner will experience some difficulty 
 in thoroughly grasping this definition of the office of chem- 
 istry, but if he reads this chapter again after he has read 
 several of the succeeding ones it is likely that the expres- 
 
BRANCHES OF NATURAL SCIENCE. 9 
 
 sions here will have a newer and fuller meaning because of 
 the facts and explanations presented later on. 
 
 It is not intended here to offer a full outline even fo all 
 the branches of natural science. 
 
 The objects and the phenomena of the world about us are 
 so varied and so interwoven aud interdependent that there 
 are subordinate natural sciences not quite coming under 
 either of the topics we have laid out, or which may be 
 closely related to two or more of them at once. 
 
 It is believed, however, that the explanation here given 
 will help to show the reader the proper position of chemistry 
 in the family of natural sciences. 
 
10 CHEMISTRY. 
 
 II. 
 
 THE SCOPE OF CHEMISTRY. 
 
 I HEMISTRY treats of all kinds of substances. This 
 is a very broad assertion, but it appears to be true. 
 The solid rock matter of the earth and the wealth 
 of living animal and vegetable substances upon it 
 undergo all their varied changes in subjection to chemical laws. 
 The same is true of the water, and of all liquid things we 
 know ; and the declaration applies yet further to the invisible 
 gaseous mass which surrounds and envelops our terrestrial 
 globe. This deeper but thinner ocean which we call the 
 atmosphere is also governed by chemical law in all its varied 
 relations to the living beings as well as to the inanimate sub- 
 stances that have their existence within it. In thought we 
 may ascend above these solid, liquid, and gaseous substances 
 connected with our earth. When thus we reach out to the 
 heavenly bodies beyond we feel sure that these, possessing 
 as they may, solid, liquid, or gaseous matter, are likewise 
 controlled by chemical laws, and that in their changes they 
 exemplify with more or less fullness distinct chemical prin- 
 ciples. 
 
 The Great Number of Different Substances in 
 the Earth. 
 
 Here, then, it is intimated that chemistry relates to an 
 enormous number of substances. In fact r the various kinds 
 of matter already recognized as existing on our earth are so 
 numerous that they have never been so much as counted, 
 much less described in any list or volume; nay, more, doubt- 
 less many exist that civilized beings have never recognized 
 at all. This last statement refers not merely to such sub- 
 stances as may be known only to savages dwelling beyond the 
 reach of civilization and commerce, nor yet to such as may 
 
THE SCOPE OF CHEMISTRY. 11 
 
 bo secreted in absolutely uninhabited portions of the globe, 
 nor even to those that exist so deep in the earth that man's 
 power may never be sufficient to reach them ; probably even 
 some of the most humble and familiar natural things, such 
 as blades of wheat, petals of daisies, silks of corn, and the 
 like, contain small quantities of distinct and separate com- 
 pounds that have not yet been recognized as such by even 
 the most skillful chemists. 
 
 But beyond all the compounds that exist in the earth, rec- 
 ognized or for various reasons unrecognized, the chemical 
 laws now known suggest the possibility of producing arti- 
 ficially a great multitude of additional substances, and even 
 more than have yet been produced in the great laboratory 
 of nature. 
 
 How it Happens that there is such a Variety. 
 
 By searching aright for the secret of the countless number 
 and the rich and splendid variety of beings that nature and 
 art present to the curious gaze of man, a comprehensive 
 answer is at last obtained. 
 
 Forms of ordinary matter may be compared to great 
 cathedrals, like those of Cologne and of Milan, which have 
 been growing for centuries, and which, by the combined 
 labor of artists and artisans, have at length become intricate 
 and beautiful structures, the admiration and delight of the 
 beholder. Just as these arise from the combination in a 
 multitude of ways of a comparatively small number of orig- 
 inal and fundamental substances like stone, brick, iron, 
 copper, plaster, glass, wood so all things known to chemists 
 are made up of a few simple substances, either existing 
 alone or in richly various combination. 
 
 The simplest substances when alone are called the chemical 
 dements, or elementary substances; the things resulting when 
 different elements are united together are called compounds. 
 Thus metallic iron is one familiar example of a chemical 
 eleme'nt ; the oxygen gas of the atmosphere is another 
 example, A piece of iron exposed to damp air soon becomes 
 
12 CHEMISTRY. 
 
 changed to a mass of iron rust. This rust is a compound; 
 it is made up of iron and oxygen united together. 
 
 In the light of what has been said the chemical elements 
 assume a new and grand importance: they are the individ- 
 uals chosen by the Creator to be the foundation stones and 
 the essential constituents of the glorious natural edifices of 
 his handiwork. 
 
 Again when the elementary individuals unite they do so by 
 reason of the interaction of many and complex forces which 
 reside, almost like soul and spirit, within the elements. 
 
 These last remarks suggest the twofold character of 
 chemical study. It involves, First, the examination of ele- 
 mentary substances and their compounds. Secondly, it 
 requires a consideration of the many general and special 
 laws and forces which determine the various possible com- 
 binations. 
 
 READING REFERENCES. 
 
 In general, the first-mentioned books in each group are 
 those which are most accessible and at the same time most 
 serviceable. Some rare and costly books are mentioned, for 
 the benefit of persons who have access to large libraries. 
 
 Chemistry, General and Applied, Serial Publications. 
 
 Chemical News. (William Crookes, Ed.) London. "Weekly. (Com- 
 menced 1860.) 
 
 Popular Science News and Boston Journal of Chemistry. Boston- 
 Monthly. (Commenced 1867.) 
 
 Journal of Chemical Society. London. Monthly. 
 
 Index to foregoing. 1841-1872; pp. 263. 
 
 Annales de Chimie et de Physique. Paris. Monthly. 
 
 Table des Tomes I a XXX. (1841-1851.) Paris, pp.134. 
 
 Table Analytique des Tomes XXXI a LXIX. 3d Series. (1851- 
 
 1863.) Paris, pp. 474. 
 
 Table des Noras d'Auteurs et Table Analytique des Matieres. 
 
 (1864-1873.) 4th Series. Paris, pp. 249. 
 
 Berichte der Deutschen Chemischen Gesellschaft. Berlin. (Com- 
 menced 1868.) 20 parts per year. 
 
THE SCOPE OF CHEMISTRY. 13 
 
 Wagner, Johannes K. v. Jahres-Bericht iiber die Fortschritte und 
 Leistungen der chemischen .Technologic. Leipzig. Annual. (Com- 
 menced 1855 ; last vol. had 1,211 pp.) 
 
 Index to foregoing. Vols. I-X. 
 
 Index to foregoing. Vols. X-XX. 
 
 Dictionaries of Chemistry, etc. 
 
 Watts, Henry. Dictionary of Chemistry and the allied branches of 
 
 other sciences. 8 vols. London. 1865-1875. 
 Storer, Frank H. First Outlines of a Dictionary of Solubilities of 
 
 Chemical Substances. Cambridge. 1864. 
 Wurtz, Ad. Dictionnaire de Chimie, pure et appliquee. 3 vols. Paris. 
 
 1870. 
 Fehling, Hermann v. Neues Handworterbuch der Chemie. A to 
 
 Phosphorsaure. Braunschweig. 1871 now issuing. 
 
 General Treatises on Chemistry. 
 
 Roscoe, H. E., and Schorlemmer, C. A Treatise on Chemistry. Lon- 
 don and New York. 1878. Vol.1, pp. 771; Vol. II, part I, pp. 
 504, part II. pp. 552; Vol. Ill, part I, pp. 724; parts II and III also 
 issued. 
 
 Cooke, Josiah P., Jr. Principles of Chemical Philosophy. Boston. 
 
 Gmelin, Leopold (Henry Watts, Tr.) Hand-Book of Chemistry. 
 Printed for the Cavendish Society. 14 vols. London. 1848-1860. 
 
 Graham-Otto's Ausfiihrliches Lehrbuch der Chemie. 6 vols. Braun- 
 schweig. 1857. 
 
 Schiitzenberger, P. Traite de Chimie ge'nerale. 5 vols. Paris. 1887. 
 
U CHEMISTRY. 
 
 III. 
 
 THE ELEMENTARY SUBSTANCES. 
 
 IN the following page is a list of the elementary sub- 
 stances now generally recognized as such. Their 
 respective symbols and their atomic weights, both 
 in exact and approximate numbers, are also given. 
 These substances, then, about seventy in number, are those 
 from which are made up all material things now known to 
 man. While it is not necessary for any one to retain such a 
 list in memory, every person who desires any considerable 
 knowledge of chemistry should be acquainted with each name 
 and the symbol attached to it, and should know something of 
 the natural sources and the properties of the substances desig- 
 nated. 
 
 Six Suggestions Conveyed by this Table. 
 
 A careful and intelligent reading of the list affords several 
 important suggestions. The following are some of them : 
 
 First. The elements are not very numerous. They are in 
 fact very few, as compared with the countless number of sub- 
 stances they may form by their proper combinations. 
 
 Second. They are, however, sufficiently numerous to pro- 
 duce the many substances recognized in nature. For, consider 
 how human language may have many words and yet all 
 these may be spelled out by combinations of few letters. 
 Some English dictionaries register over a hundred thousand 
 words, yet these are all made by the combinations of less 
 than thirty letters. Now it is easy to comprehend how the 
 few letters of an alphabet may be even still further combined 
 in various ways so as to produce additional words almost with- 
 out limit ; in a similar manner it may be easily imagined that 
 the elementary substances of the chemist have ample capabili- 
 ties for giving rise not only to the compounds now known, but 
 W /et more and more, almost without limit. It is true that 
 
THE ELEMENTARY SUBSTANCES. 
 
 15 
 
 The Chemist's Elementary Substances. 
 
 Name of 
 Element. 
 
 Atomic Symbol. 
 
 Exact 
 Atomic 
 Weight. 
 
 Approximate 
 Atomic W'ght. 
 
 Name of 
 Element. 
 
 Atomic Symbol. 
 
 Exact 
 Atomic 
 Weight. 
 
 Approximate 
 Atomic W'ght. 
 
 Aluminium.. 
 Antimony... 
 
 Al 
 Sb (Stibium) 
 As 
 
 27.0090 
 119.9550 
 74.9180 
 136.7630 
 2075230 
 10.9410 
 79.7680 
 111.8350 
 132.5830 
 39.9900 
 11.9736 
 140.4240 
 35.3700 
 52.0090 
 53.8S70 
 63.1730 
 144.5730 
 165.8910 
 18.9810 
 63.8540 
 
 9.0850 
 196.1550 
 1.0000 
 113.3980 
 126.5570 
 192.6510 
 55.9130 
 138.5260 
 206.4710 
 7.0073 
 23.9590 
 55.9060 
 199.7120 
 
 27. 
 120. 
 74.9 
 136.8 
 207.5 
 1(1.9 
 79.8 
 111.8 
 132.6 
 40. 
 12 
 140.4 
 35.4 
 52. 
 58.9 
 63.2 
 144.6 
 165.9 
 19. 
 68.9 
 72.3 
 9.1 
 196.2 
 1. 
 113.4 
 126.6 
 192.7 
 55.9 
 138.5 
 206.5 
 7. 
 24. 
 53.9 
 199.7 
 
 Molybdenu.n 
 Nickel 
 
 Mo 
 Ni 
 
 95.5270 
 57.9280 
 93.8120 
 14.0210 
 198.4910 
 15.96)3 
 105.7370 
 30.9580 
 19 J. 4150 
 39.0190 
 101.0550 
 85.2510 
 104.2170 
 150.0210 
 43.9800 
 78.7970 
 28.1950 
 107.6750 
 22.9980 
 87.3740 
 31.9840 
 182.1440 
 127.9600 
 203.7150 
 233.4140 
 117.6980 
 47.9997 
 183.6100 
 238.4820 
 51.2560 
 172.7610 
 89.8160 
 64.9045 
 89.3670 
 
 95.5 
 
 57.9 
 93.8 
 14. 
 198.5 
 16. 
 105.7 
 31. 
 194.4 
 39. 
 104.1 
 85.3 
 104.2 
 150. 
 44. 
 78.8 
 28.2 
 107.7 
 23. 
 87.4 
 32. 
 182.1 
 128. 
 203.7 
 233.4 
 117.7 
 48. 
 183.6 
 238,5 
 61.3- 
 172.8 
 8.98 
 64.9 
 89.4 
 
 Niobium 
 Nitrogen 
 
 Nb 
 N 
 
 09 
 
 Barium 
 
 Ba 
 Bi 
 
 
 B 
 
 
 
 
 
 Br . . . 
 
 Palladium... 
 Phosphorus . 
 
 Pd 
 
 Cadmium . . . 
 Caesium 
 Calcium 
 Carbon 
 
 Cd 
 Cs 
 Ca . 
 
 c 
 
 p 
 
 Pt 
 
 Potassium... 
 Rhodium 
 Rubidium 
 
 K(Kalium) 
 Rh 
 Rb 
 
 Cerium 
 Chlorine 
 Chromium... 
 Cobalt 
 Copper 
 Didymium. . . 
 
 Ce 
 CI 
 
 Ruthenium.. 
 
 Ru 
 Sm . 
 
 Cr 
 Co 
 Cu (Cuprum) 
 D 
 
 Scandium.... 
 Selenium 
 Silicon 
 
 Sc 
 
 g e 
 
 Si 
 
 E.... 
 
 Silver 
 Sodium 
 Strontium . . . 
 Sulphur 
 Tantalum 
 Tellurium.... 
 
 Ag(Argentum).. 
 Na (Natrium.... 
 Sr 
 g 
 Ta 
 Te 
 Tl 
 
 
 p 
 
 Gallium 
 Germanium. 
 Glucinum . . . 
 Gold 
 
 Ga 
 Ge 
 GorBe(Deryllium 
 Au (Aurum) 
 H 
 
 
 In 
 
 Thorium 
 Tin 
 
 Th 
 Sn (Stannum)... 
 Ti 
 
 
 
 Iridium . . 
 
 
 Titanium 
 Tungsten 
 
 Iron 
 Lanthanum . 
 Lead 
 Lithium 
 Magnesium.. 
 Manganese.. 
 Mercury 
 
 Fe (Ferrum) 
 La 
 ?b (Plumbum) . . 
 Li 
 Mg '' 
 Mn 
 
 W(Wolframium) 
 
 u 
 
 Vanadium .. 
 Ytterbium... 
 Yttrium 
 
 Va .. 
 
 Yh 
 
 Y 
 
 Zinc .... 
 
 Zn 
 
 Hg (Hydrargyrum 
 
 Zirconium... 
 
 Zr 
 
16 CHEMISTRY. 
 
 the chemist discovers in some of the chemical elements a limit 
 to the power of union, but in others he finds an apparently un- 
 bounded capacity to form new arrangements and combinations. 
 
 Third. Most of the elements are uncommon. Only about 
 one sixth of them are familiar to ordinary readers. Thus 
 carbon, copper, gold, iron, lead, mercury, nickel, silver, sul- 
 phur, tin, zinc, are almost the only names in the list that can 
 be said to suggest familiar things. Indeed some members 
 of this list exist in the earth in extremely small quantities ; 
 but man by his ingenuity and industry has gathered up even 
 these and brought them near to the hand of every civilized 
 being. Thus gold exists in the earth so far as man has 
 access to the earth in only very minute amounts ; yet gold 
 has a multitude of common uses beside its employment in 
 coinage. Various forms of decorative art, like gilded letter- 
 ing on books, afford familiar examples. So also mercury, 
 which in the ordinary thermometer is very familiar 
 to every one, exists in the earth in but minute amounts. 
 
 When the chemist examines still more narrowly the com- 
 position of the terrestrial globe, he discovers an inequality 
 yet more extraordinary than that hinted at. Thus it appears 
 that probably one half of our entire planet consists of a 
 single substance (that is, oxygen) and that one quarter of it 
 consists of another single substance (that is, silicon). Since 
 an amount equal to three quarters of the earth's mat- 
 ter, by weight, is made up of but two elements, the remain- 
 ing ones may be expected to exist in much smaller proportions. 
 
 The following table, given by Roscoe and Schorlemmer, 
 shows the average composition of the earth's crust so far as it 
 is accessible to human investigation by means at present known: 
 
 Percentage Composition of the Earth's Solid Crust. 
 
 (BY WEIGHT.) 
 
 Oxygen 44.0 to 48.7 per cent. 
 
 Silicon 22.8 36.2 " 
 
 Aluminium... 9.9 6.1 " 
 
 Iron 9.9 2.4 " 
 
 Calcium 6.6 0.9 u 
 
 Magnesium.... 2.7 to 0.1 percent. 
 
 Sodium 2.4 2.5 " 
 
 Potassium.. 1.7 3.1 " 
 
 100.0 100.0 
 
THE ELEMENTARY SUBSTANCES. 17 
 
 In this table about sixty elements are not mentioned. 
 Many of these occur in exceedingly small quantities and also 
 in special localities. Their relative rarity is rendered all the 
 more striking when it is considered that in a minute frac- 
 tional part of the whole must be included all coal and all the 
 useful metals, except iron. 
 
 Another authority * declares that it is probable that an 
 amount equal to ninety-nine one hundredths of the entire 
 weight of the solid, liquid, and gaseous matter of our globe 
 is made up of only thirteen elementary substances. The 
 elements referred to and their relative proportions are 
 approximately represented in the diagram following : 
 
 Diagram of the Composition of Our Globe. 
 
 (BY WEIGHT.) 
 
 Sulphur, Hydrogen, 
 Chlorine, Nitrogen, 
 
 About 55 
 others. 
 
 Potassium, Sodium, 
 Iron, Carbon. 
 
 SILICON", 
 
 Aluminium, 1 
 Magnesium, > 
 Calcium, ) 
 
 OXYGEN", 
 
 Fourth. Most of the elements are metals. This may not 
 appear to the ordinary reader until he is informed that ter- 
 minations in um, as in case of aluminium, barium, cadmium, 
 calcium, and others, are intended to suggest that the sub- 
 
 ' Professor J. P. Cooke. 
 
18 CHEMISTRY. 
 
 stances so designated are metals. Most of the other elements 
 having names not terminating in um are called non-metals. 
 
 Fifth. Each chemical element has an atomic symbol, an 
 abridgement, in some form, of its name. 
 
 Sixth. Each chemical element has an atomic weight. As 
 the atomic weight of hydrogen is 1, without any fraction, it 
 is easily understood that the weight of one atom of hydrogen 
 is taken as the unit of the system. An inspection of the 
 numbers given shows that in many cases the atoms weigh 
 amounts that are very nearly exact multiples of the weight 
 of an atom of hydrogen. 
 
 READING REFERENCES. 
 Atomic Weights, Calculations of 
 
 Becker, George F. Atomic "Weight Determinations : a digest of the 
 investigations published since 1814. (Published as Part IV. of the 
 Constants of Nature, in Smithsonian Miscellaneous Collections, No. 
 358). 1880. 
 
 Clarke, Frank W. A Recalculation of the Atomic Weights. (Published 
 as Part V. of the Constants of Nature, in Smithsonian Miscellaneous 
 Collections, No. 441). 1882. 
 
 Am. Chem. Jour, iii, 263. (1881.) 
 
 Atomic Weights, Periodicity of 
 
 Meyer, Lothar. Chem. News, xli, 203. 
 
 Atomic Weights, Mendelejeff s Law of 
 
 Am. Chem. Jour. iii, 455. 
 
 Cooke, J. P. Chem. Philosophy, p. 265. 
 
 Wurtz, Ad. Atomic Theory, p. 154. 
 
 Atomic Weights, Arithmetical Relations of 
 
 Hodges, M. D. C. Silliman's Journal, 3d Ser. x, 2ft. 
 Nevvlands, J. A. R. Chem. News, xlix, 198. 
 
 Atomic Weight of Oxygen. 
 
 Odling, W. Jour, of Chem. Soc. of London, xi, 107. 
 
 Atomic Weight of Thallium. 
 
 Crookes, Wm. Chem. News, xxix, 14, 29, 39, 55, 65, 75, 85, 97, 105, 
 115, 126, 137, 147, 157, 
 
THE ELEMENTARY SUBSTANCES. 19 
 
 Atomic Weights, Prout's Hypothesis of 
 
 Cooke, J. P. Chemical Philosophy, 270. 
 
 Clarke, F. W. Arn. Cliem. Journal, iii, 272. (1881.) 
 
 Gerber, Silliman's Journal, 3d Ser. xxvi. 236. 
 
 Atoms, Absolute Weight of 
 
 Annaheim, J. Jour, of Chem. Soc. of London, xxxi, 31. 
 
 Elements, Defunct 
 
 Bolton, H. C. American Chemist, i, 1. 
 
 Elements, Suggestions that they are Compound. 
 
 Lockyer, J. X. Nature, Jan. 2 and 9, also Nov. 6, 1879. 
 Hastings, C. S. Criticism of above. Am. Chem. Jour., i, 15. 
 Gladstone, J. H. Chem. News, 48, 151. 
 Brodie, Sir B. Chem. News, 15, 295. 
 Carnelley, T. Chem. News, 53, 183, 197. 
 Ciookes, W. Chem. News, 54, 115. 
 
20 CHEMISTRY. 
 
 IV. 
 
 NAMES AND SYMBOLS OF ELEMENTS. 
 
 INY history of the chemical elements distinctly points 
 to the enormous stride which chemical discovery 
 has taken within the last hundred years. The 
 dawn of this period was marked by many most 
 important results. Among these may be mentioned the 
 detection of the elementary gases : oxygen, hydrogen, and 
 nitrogen. The light which these great events threw upon 
 the future of the science enabled the chemists of that early 
 period to perceive that the number of new compound sub- 
 stances then discovered, and likely soon to be discovered, 
 called for a multitude of new terms. In 3787 the eminent 
 French chemist, Lavoisier, in committee with Guyton de 
 Morveau and others of their chemical associates of the 
 French Academy, suggested a system by which a consider- 
 able number of chemical compounds, both then known and 
 thereafter to be discovered, might be provided with names 
 at once convenient and suggestive. This system, slightly 
 modified and considerably extended to accommodate the 
 yet more widely expanding needs of the science affords the 
 basis of the chemical language of to-day. 
 
 A Few Principles of Chemical Language. 
 
 It is proposed to explain here a few of the first principles 
 of chemical nomenclature and notation that is, to present 
 a few of the rules by which significant and useful names and 
 symbols are provided. These will be found to supply the 
 requirements of hitherto inaccurately known substances, and 
 even of those formerly unknown. 
 
 Mrst, the names of elementary substances long known are 
 retained. Thus, gold and silver are metals that were 
 known in the earliest historical periods, if not in prehistoric 
 times ; their names, therefore, still remain in use. 
 
NAMES AND SYMBOLS OF ELEMENTS. 
 
 Second, t/ie discoverers of new elementary substances assign 
 the names. In so doing they usually invent a name that sug- 
 gests some fact connected with the substance itself. Thus 
 the name nitrogen is derived from two Greek words (virpov, 
 nitron, mineral alkali, and yzvvcu,), gennao, I produce) carry- 
 ing the suggestion that the gas is one of the constituents of 
 nitre. The name hydrogen is derived from two Greek 
 words (vdi^o, hydor, water, and yevvdu, f/ennao, I produce,) 
 indicating that wherever water exists hydrogen is an essen- 
 tial constituent of it. So the name chlorine is derived from 
 a Greek word (%/twpof, chloros, green,) which reminds the 
 chemist of the fact that chlorine gas possesses a greenish 
 color. The substance oxygen, however, was named in a 
 different manner. Its name is derived from two Greek 
 words (o^vg, oxys, acid, and yevvdb), gennao, I produce,) sig- 
 nifying a generator of acids. It appears, then, that in this 
 case the name is based, not on an easily verified fact, but 
 upon a theory, current when oxygen was discovered, of the 
 action of the substance in question. In a certain sense a name 
 thus formed may be considered ill-advised. Thus in the case 
 in hand it has turned out that while oxygen is a constituent 
 of a majority of known acids, it is not essentially an acidifying 
 substance : many acids are known that contain no oxygen 
 at all, and again there are a multitude of compounds contain- 
 ing oxygen that are not acids in any proper sense. 
 
 Third, newly discovered metals are usually given names 
 which, while they suggest some property of the substance, have 
 in addition the termination, um. Thus the metal thallium 
 derives its name from a Greek word (0aA/lo, tliallos, a green 
 twig,) which carries the suggestion of the fact that thallium 
 and its compounds when highly heated evolve light of a 
 delicate green color. Again, caesium, a newly discovered 
 metal, has a name derived from a Latin word (caesius, blue,) 
 which refers to the fact that caesium and its compounds 
 when highly heated afford light of a blue color. The ter- 
 mination um is used for metals, after the analogy of the 
 Latin language which usually has its names of metals end in 
 
Fia. 1. Antoine Laurent Lavoisier. Born in Paris, August 26, 1743; died on tte scaffold 
 
 in Paris, May 8, 1794. 
 
 (22) 
 
NAMES AND SYMBOLS Off ELEMENTS. 23 
 
 um. Indeed, the chemist often makes use of the Latin 
 names of even those metals that have been long known by 
 more familiar ones. Thus for gold the Latin word aunim is 
 used, for silver the Latin word argentum, for lead the Latin 
 word plumbum. It will be seen later that slightly modified 
 forms of these names are very frequently employed when 
 compounds of these metals are to be designated. 
 
 Symbols Used for Atoms. 
 
 Each elementary substance, or, strictly speaking, the mi- 
 nute quantity of it represented by the term one atom, may be 
 designated in brief by a special letter or short group of letters 
 called the symbol. The usual symbol is the initial letter of 
 the native or the Latin name of the substance. Upon exam- 
 ining the list of elementary substances at page 15, it will be 
 seen that the following nine of the names begin with the 
 letter c; of course, therefore, in eight cases at least, the 
 symbol must contain an additional distinguishing letter. 
 
 Accordingly C indicates one atom 
 Ca 
 Cd 
 Ce 
 Cl 
 
 Co " 
 
 Cr 
 
 Cs 
 Cu " 
 
 of Carbon ; 
 Calcium ; 
 Cadmium ; 
 Cerium ; 
 Chlorine ; 
 Cobalt; 
 Chromium ; 
 Caesium ; 
 Copper (Latin word cuprum). 
 
 It also appears that in the case of metals, like iron and 
 copper, known to the ancients, the symbols used are derived 
 from the Latin names. The use of these symbols made from 
 letters and therefore called literal symbols, from the Latin 
 word litera, a letter will become apparent as the reader 
 advances ; but it is easily perceived that they afford a con- 
 venient abridgment of the longer titles of the elements. 
 
 The use of literal symbols as an abridgment of the chem- 
 ical nomenclature was first proposed by Berzelius, a Swedish 
 chemist, whose eminence in every branch of the science was 
 
FIG. 2. Jons Jakob Berzelius. 
 
 Born in East Gothland (in Sweden), August 20, 1799 ; died 
 August 7, 1848. 
 
NAMES AND SYMBOLS OF ELEMENTS. 25 
 
 such that the suggestion here referred to constitutes one of 
 the least of the many and substantial grounds on which his 
 fame rests. 
 
 READING REFERENCES. 
 Alchemy. 
 
 Rod well, G. F. The Birth of Chemistry. London. 1874. 
 Draper, J. C. Amer. Chemist, v, 1. 
 
 Mackay, Charles. Memoirs of Extraordinary Popular Delusions. 2 v. 
 London. 1869. i, 93. 
 
 Derzelius. 
 
 Wohler, F. Early Recollections of Berzelius. Am. Chemist, vi, 131. 
 
 Chemistry, History of 
 
 Thomson, Thomas. History of Chemistry, 2 v. London. 1830. 
 Hoefer, F. Histoire de la Physique et de la Chimfe. Paris. 1872. 
 Kopp, Hermann. Gesehichte der Chemie. 4Th. Braunschweig. 1843. 
 Die Entwickelung der Chemie in der neueren Zeit. Miinchen. 
 
 1873. 
 
 Die Alchemie. 2Th. Heidelberg. 188G. 
 Bolton, H. C. Chem. News, xxxii, 36, 56, 68. 
 Liebig, J. v. Familiar Letters on Chemistry. 
 Whewell, Wm. History of the Inductive Sciences. 2 v. New York. 
 
 1875. ii, 259. 
 
 Lavoisier. 
 
 Thomson, Thomas. History of Chemistry. 2 v. London. 1830. 
 
 ii, 75. 
 
 Figuier L. Vies des Savants Tllustres du xviii siecle, 444. 
 Brougham, H. Lives of Philosophers of the time of George III. 
 
 Edinburgh. 1872. 290. 
 Grimaux, E. La mort de Lavoisier. Revue des Deux Mondes. 
 
 LXXIX. 884. 
 
 nomenclature. 
 
 Morveau, Guyton de. Mcmoire sur les denominations chimiques, la 
 necessite d'en perfectionner le systeme, les regies pour y parvenir, 
 suivi d'un tableau d'une nomenclature chemique ; Dijon. 1782. 
 
 Lavoisier, de Morveau, Fourcroy. Baume, Hassenfratz, Adet and others. 
 Methode de nomenclature chimique. Paris. 1787. (The Boston 
 Athenaeum Library contains a copy of this work.) 
 
 Gmelin's Proposed Nomenclature. 
 
 Wurtz Dictionnaire. ii. Part I. 575. 
 Gmelin Hand-Buch. v, 132. 
 
 Odling, W. Chem. News, 52, 181, 203, 216. (Plea for the empiric 
 naming of compounds.) 
 
26 CHEMISTRY. 
 
 V; 
 
 CLASSIFICATION OF THE ELEMENTARY 
 SUBSTANCES. 
 
 speaking of the elementary substances some of 
 them have been referred to as metals. What, then, 
 is the exact idea conveyed by this designating 
 term ? Every one can readily picture in his mind 
 some metal or metals like gold, silver, tin, zinc, and others, that 
 have certain common characteristics, such as great weight, and 
 the peculiar brilliancy and power of reflecting light which is 
 described as metallic lustre. Another well marked and 
 widely recognized characteristic at once thought of is the 
 facility with which the substances ordinarily known as metals 
 may be beaten or rolled into thin layers. This property, 
 called malleability (a word derived from the Latin word 
 malleus, a hammer), is not possessed in any striking degree 
 by substances other than metals. Thus, sulphur is not malle- 
 able quite the contrary; it is very brittle. Charcoal, which 
 consists mostly of the elementary substance called carbon, is 
 likewise not malleable ; neither of these last two substances 
 would be likely to be considered by even an ordinary 
 observer as metals. In fact they are classed as non-metals 
 by the chemist. This division of the elementary substances 
 into metals and non-metals is dwelt upon, not because it can 
 be called a very important one, but because it is widely used 
 in works on chemistry and because in deciding to which of 
 these two classes a given substance belongs, ultimate depend- 
 ence must be placed upon its chemical characteristics rather 
 than upon its mere mechanical properties. 
 
 The Meanings Associated with the Term Metal. 
 
 The principal properties referred to are best presented in 
 three groups : 
 
 First. Metallic Properties Associated with Mechanical 
 
CLASSIFICATION OF THE ELEMENTS. 27 
 
 Relations. An elementary substance accepted as a metal 
 must possess the property of existing in a solid condition ; a 
 weight rather greater than that of most well-known sub- 
 stances ; considerable hardness, malleability, ductility (that 
 is, the capability of being drawn out into fine wire). 
 
 Second. Metallic Properties Associated with Physical Rela- 
 tions. A metal should possess the metallic lustre; the power 
 called opacity, by reason of which it does not allow light to 
 pass through it ; the noticeable capability of allowing heat 
 to flow in it, called the power of conducting heat ; the capac- 
 ity for allowing the electric current to flow readily in it, called 
 good conducting power for electricity. 
 
 Third. Metallic Properties Associated with Chemical Rela- 
 tions. A metal should possess the power and the tendency 
 to readily form a chemical union with oxygen ; the chemical 
 power to act upon compounds containing hydrogen in such 
 a way as to turn the hydrogen out and take its place in 
 the old compound and thus form a new one ; the relationship 
 toward the electric current such that, when the element is 
 subjected to the galvanic battery, it tends to gather about 
 the negative pole in consequence of which characteristic it 
 is usually called electro-positive. 
 
 But while no known metal appears to possess the entire 
 range of properties with which in thought the ideal one is 
 endowed, every substance classified as a metal should possess 
 many of them. 
 
 An illustration of what has been said may be found in 
 metallic mercury. From the fact that under ordinary con- 
 ditions it is a liquid it is plain that mercury must lack certain 
 of the metallic properties referred to; that is, it does not 
 possess the solid form, it does not possess hardness, it does 
 not possess malleability, it does not possess ductility. Yet 
 if it is cooled to a low temperature about forty degrees 
 below zero it freezes; in other words, becomes solid; then 
 it possesses many of the distinctly metallic features that it 
 necessarily lacks when in the ordinary liquid condition. Of 
 course this liquid condition is a mere incidental circum- 
 
28 CHEMISTRY. 
 
 stance, due to the temperature which ordinarily prevails upon 
 our earth. If our ordinary temperature were slightly lower 
 than forty degrees below zero mercury would then be com- 
 monly known as a solid, hard, lustrous, heavy, malleable 
 metal capable, of course, of melting with a slight accession 
 of heat. 
 
 As a further illustration, in a somewhat different direction, 
 mention may be made of the metal lithium. This substance 
 cannot be called heavy, since it is lighter than water; indeed 
 it is the lightest solid known. But on the other hand it pos- 
 sesses in a striking degree those chemical features of metals, 
 such as strong affinity for oxygen and tendency to combine 
 with it, which have already been detailed in our definition 
 of the ideal metal. 
 
 The Term Non-Metal. 
 
 The term non-metal is suggestive of a negative idea, and 
 not of any definite or positive one. In fact it is intended to 
 intimate that elementary substances of this class are those 
 which do not properly belong to the other. Sulphur and 
 carbon have been already alluded to as examples of non- 
 metals ; other non-metals, such as oxygen, hydrogen, nitro- 
 gen, fluorine nnd chlorine among the gases, bromine, a liquid, 
 and iodine, antimony, phosphorus, arsenic, boron, silicon and 
 selenium, among solids, are far less familiarly known to most 
 persons. 
 
 READING REFERENCES. 
 Elements, Classification of 
 
 Williamson. A. W. Jour, of Chem. Soc. of London, xvii, 211. 
 Chemical Theory. 
 
 Cooke, Josiali P., Jr. The-Xew Chemistry. New York. 1874. 
 
 Remsen, Ira. Principles of Theoretical Chemistry. Philadelphia. 
 1887. 
 
 Tilden, William A. Introduction to the Stud}' of Chemical Philosophy. 
 
 Wurtz, Ad. (Henry Watts, Tr.) History of Chemical Theory. Lon- 
 don. 1869. 
 
COMPOUND SUBSTANCES. 29 
 
 VI. 
 
 COMPOUND SUBSTANCES. 
 
 a previous chapter a list of elementary sub- 
 stances has been given. All other matters known 
 are compounds. From what has been said already 
 it is evident that the compounds are very numer- 
 ous, indeed that there is practically no limit to the number 
 of possible ones. These compounds are all made up by the 
 union of elementary substances in obedience to the peculiar 
 chemical forces that reside within them. Some compounds 
 have only two kinds of elements: they are called binaries. 
 Some compounds have three kinds of elements: they are 
 called ternaries. Other compounds may have four, five, six, 
 or even more kinds of elements grouped together to form 
 one sort of substance. It this place reference will be made 
 principally to binaries and ternaries that is, to the com- 
 pounds of the simpler forms of constitution. 
 
 Examples of Binary Compounds. 
 
 In discussing binaries it will be well to give at the outset 
 three or four examples for the purpose of illustration. 
 
 First. The gas known as hydrogen and the gas known as 
 chlorine have the power of combining chemically and pro- 
 ducing an entirely new compound, a compound different from 
 hydrogen and different from chlorine, yet containing por- 
 tions of each of them. This compound is a binary since it 
 consists of but two kinds of elements. It has several names, 
 one of which is hydric chloride. The chemist frequently repre- 
 sents what is evidently the smallest possible quantity of this 
 substance, and also its exact composition, by the expression 
 
 H 01. 
 
 It is plain that this expression means a minute portion of 
 substance formed by the union of one atom of hydrogen, 
 
30 CHEMISTRY. 
 
 (expressed by II,) and one atom of chlorine (expressed by 
 Cl). 
 
 Second. When sulphur burns in the air it produces a blue 
 flame. At the same time a new and peculiar gas is formed 
 which is easily recognized by its choking odor, similar to 
 that given off by a burning sulphur match. Now this odor 
 is one of the properties of a new compound that has been 
 formed: a compound different from sulphur, different from 
 oxygen, yet containing them both and produced by the union 
 of them. The compound is a binary because it contains but 
 two kinds of elements. It is called sulphur dioxide. The 
 name is intended to suggest that there are two atoms of 
 oxygen to one of sulphur in the compound. This idea is 
 further conveyed by the abridged system of notation so 
 commonly used by chemists. Thus by this system the 
 smallest possible quantity of the compound in question is 
 expressed as follows, 
 
 S0 2 . 
 
 In this expression it is very plain that S stands for one atom 
 of sulphur, and O.^ for two atoms of oxygen. 
 
 Third. But sulphur may be made to combine with a still 
 larger amount of oxygen than it takes when it simply burns 
 in the air. Then it forms a compound called sulphur triox- 
 ide. This is still a binary, since it contains nothing but sul- 
 phur and oxygen that is, only two elementary substances. 
 Expressed in the briefer form the smallest quantity of this 
 compound may be expressed by the formula, 
 
 S0 3 . 
 
 This expression means a compound arising from the union of 
 one atom of sulphur and three atoms of oxygen. 
 
 Fourth. When lead is heated to the melting point in the 
 dir it is observed to become coated with a constantly increas- 
 ing mass of a kind of ashes. A pound of the lead when 
 heated in this way produces considerably more than a pound 
 of dross. The formation of this dross is explained by the 
 fact that when lead is heated it really burns, though of 
 
COMPOUND SUBSTANCES. 31 
 
 course the rapidity of the burning depends upon the 
 amounts of heat and air to which the lead is subjected. 
 Evidently the lead, in burning, has something added to 
 itself. That something is a gas which is ever present in the 
 atmosphere and which is called oxygen. The dross is a 
 chemical compound of lead and oxygen. It is called, plumbic 
 oxide, and its smallest quantity is represented by the for- 
 mula, 
 
 PbO. 
 
 In this formula it is easy to see that Pb stands for an atom 
 of lead (whose Latin name is plumbum), and O for an atom 
 of oxygen. The dross, then, is a binary compound. 
 
 A multitude of such examples of binary compounds might 
 be given ; probably those already cited are sufficient for the 
 present. It will be advantageous to the reader to carefully 
 learn the names and the formulas of the binary compounds 
 thus far given, since they are selected examples which may 
 be used again further on. 
 
 Examples of Ternary Compounds. 
 
 The ternary compounds are those which consist of three 
 kinds of elements ; of course they are more complicated in 
 structure than the binaries. This fact, however, must not 
 deter the reader from the attempt to understand them at the 
 outset, for the principal ternaries are acids and salts, and 
 every one knows that acids and salts are among the most im- 
 portant compounds which the chemist has to employ. 
 
 As examples of ternary acids mention will be made of 
 two of the principal ones used by the chemist. 
 
 And first, nitric acid is a compound of hydrogen, nitrogen, 
 and oxygen. The formula of the smallest individual portion 
 
 of it is 
 
 HN0 3 
 
 These letters signify that nitric acid contains one atom of 
 hydrogen, combined with one atom of nitrogen and three 
 atoms of oxygen. Now this nitric acid forms a great many 
 salts. A simple example may be found in that one contain- 
 
32 CHEMISTRY. 
 
 ing silver. Thus when nitric acid and silver are warmed 
 together, either a part or the whole of the silver dissolves. 
 A new substance is produced which is commonly called 
 nitrate of silver. By the chemist it is oftener called argen- 
 tic nitrate. Its solution may be dried into the form of a 
 white crystalline substance, one that has long been accepted 
 as a member of the class of salts. Its formula is 
 
 AgN0 3 . 
 
 It is plain that this last formula is employed as a short 
 way of expressing that the salt is a compound of more than 
 one kind of element of three kinds in fact and that these 
 elements are in the proportions of one atom of silver, one 
 atom of nitrogen, and three atoms of oxygen. 
 
 Promise was made to refer to two important acids ; sul- 
 phuric acid is the second one. Commercially this substance 
 is by far the most important of all the acids. Indeed, its 
 manufacture is one branch of the greatest chemical indus- 
 try devised by man the alkali trade. Evidently it is im- 
 portant that the chemist should be thoroughly acquainted 
 with sulphuric acid; with its composition, its formula, its 
 way of chemically acting on other substances, and the things 
 or products that it gives rise to when it has opportunity so 
 to act. Now sulphuric acid has the formula 
 
 H 2 S0 4 . 
 
 This formula means that sulphuric acid is a ternary, being 
 made up of three different kinds of elements ; namely, two 
 atoms of hydrogen, one atom of sulphur, and four atoms of 
 oxygen. 
 
 Further, sulphuric acid forms a large number of salts. 
 Thus it forms one containing silver. This is commonly 
 called sulphate of silver, though the chemist generally calls 
 it argentic sulphate. The formula of argentic sulphate is 
 
 Ag 2 S0 4 . 
 
 When this formula is firmly acquired by the reader so that 
 he can readily compare it with others already mentioned, a 
 
COMPOUND SUBSTANCES. 33 
 
 certain simple and distinct relationship may be traced. Thus 
 comparing 
 
 Argentic sulphate, Ag 2 S0 4 
 
 with Sulphuric acid, H 2 S0 4 
 
 it is evident that in the one two atoms of silver have taken 
 the place of two atoms of hydrogen that appeared in the 
 other. And such is usually the case: when silver takes the 
 place of hydrogen, it does so atom for atom. Indeed argen^ 
 tic nitrate, AgNO 3 , already described, illustrates this fact. 
 It is a compound product closely related ta nitric acid, 
 HNO 3 , the only difference of construction being that here 
 also one atom of silver has taken the place of one atom of 
 hydrogen. 
 
 The Purpose of this Chapter. 
 
 The purpose of this chapter has been to suggest a few 
 facts respecting the nature of chemical compounds and also 
 to show how the science of chemistry employs its peculiar 
 language both in its longer and shorter forms. This lan- 
 guage is very comprehensive. In fact it is too elaborate for 
 full explanation here. The plan contemplated is to give at 
 this point a few hints as to its nature and scope, and to de- 
 velop it only so far as may be necessary to the succeeding 
 stages of our progress. 
 
 It is proper to suggest at this point that no single scientific 
 man nor society of them can enforce the use of any par- 
 ticular words upon the great body of chemists. For this 
 reason, as well as for others, there still prevails the use of 
 different chemical names for the same substance. Thus the 
 compound of hydrogen and chlorine first referred to as rep- 
 resented by the formula H Cl, has at least four widely used 
 names: first, a name merely suggestive of its component 
 parts that is, hydric chloride ; second and third, names 
 which suggest something in addition to its component parts; 
 namely, that it is an acid thus it is called both hydro chloric 
 acid and chlorohydric acid ; fourth, an old-fashioned name 
 3 
 
CHEMISTRY. 
 
 which still retains its hold upon the commercial world, 
 namely, muriatic acid. 
 
 This same general principle applies to a great many other 
 substances, and while it is true that it thus increases the 
 number of names in the chemical language, it likewise inci- 
 dentally enriches that language. For in many cases it has 
 come to pass, little by little, that these different names are 
 appropriated to slightly different forms of the same sub- 
 stance, and so the name employed often conveys to the intel- 
 ligent chemist as definite a shade of meaning as do the 
 different synonyms used in the description of every-day 
 affairs by any accomplished author. A single example will 
 elucidate this point. The term oil of vitriol would usually 
 be defined as meaning sulphuric acid. But the words sul- 
 phuric acid convey, strictly speaking, the same meaning as 
 the formula 
 
 H 2 S0 4 
 
 This latter substance, however, is of very rare occurrence 
 alone ; it is flsually associated with varying quantities of 
 water, and is then spoken of as sulphuric acid of varying 
 degrees of dilution. Now the manufacturing chemists of 
 the United States have adopted a definite mixture of sul- 
 phuric acid (H 2 SO 4 ) and water (H 2 O) as an exact thing to be 
 called oil of vitriol. It is that dilution consisting of 
 
 93.5 per cent, of sulphuric acid, H 2 S0 4 
 
 with 6.5 per cent, of water, H 2 
 
 both taken by weight. 
 
 READING REFERENCES. 
 Notation, Chemical. 
 
 Frankland, E. Experimental Researches in Chemistry. 8. London. 
 
 187Y. 
 
 Williamson, A. W. Jour, of Chem. Soc. of London, xvii, 421. 
 Frankland, E. Loc. cit xix, 372. 
 Madan. H. G. Loc. cit. xxiii, 22. 
 
 Council Chem. Soc. of London. Instruction's to Abstractors from Cur- 
 rent Publications. (1879.) Chem. News, xlvii, 15. 
 
THE CONSTRUCTION OF SUBSTANCES. 
 
 VII. 
 
 THE CONSTRUCTION OF SUBSTANCES. 
 
 order to understand the chemical construction 
 of substances it is necessary to consider three 
 terms much used by the chemist; these terms 
 are : 
 
 Mass. 
 
 Molecule, 
 
 Atom. 
 
 Evidently the words relate to three grades of magnitude 
 in which matter is capable of existing ; it is equally plain 
 that of the series the mass represents the largest individual 
 portion of substance, and the atom the smallest, while the 
 molecule represents the intermediate one. 
 
 The Chemical Use of the Term Mass. 
 
 Whoever looks about him sees substances existing in 
 masses. This is true of vast mountain chains and equally true 
 of the smallest grains of matter that are recognized as the 
 humblest components of those peaks. 
 
 But the smallest of these visible masses is made up of par- 
 ticles still more minute yet, perhaps, of precisely the same 
 kind. For the chemist possesses means of subdivision of 
 substances by which he may make them into minute frac- 
 tional parts that are measurable and are all just alike, and 
 he may continue this process long after the portions have 
 sunk below the reach and range of ordinary vision. A 
 lump of pure sugar as big as a cubic inch may be mechanic- 
 ally divided by any one into many smaller ones, each little 
 one being easily recognized by the ordinary senses as possess- 
 ing the sweetness, the crystalline construction, the white- 
 ness, the solidity, the brilliancy, the power of dissolving in 
 water, and perhaps other well-known characteristics that per- 
 
36 CHEMISTRY. 
 
 tain to sugar. But the chemist is able to continue the sub- 
 division of the sugar much further. This he does by recourse 
 to processes not exactly mechanical, though closely allied to 
 them ; by processes often called physical as distinguished 
 from purely mechanical ones. He may thus reduce the 
 sugar to fragments of such extreme minuteness that while 
 they do not impress our senses as larger portions do, yet each 
 fragment is capable of displaying to a competent scientific 
 observer the certain and sure chemical properties that always 
 belong to sugar, whether in large lumps or in small ones, and 
 which in fact belong to nothing but sugar. 
 
 Speaking generally, all particles producible by mechanical 
 subdivision are masses, while the same is true of most par- 
 ticles producible by physical subdivision. 
 
 The Chemical Use of the Term Molecule. 
 
 But there is a point where any attempt at further scien- 
 tific subdivision results in a new and startling change : at 
 this stage the last individual that can properly be called 
 sugar is dissected and loses entirely the characteristics of 
 sugar. The fragments produced by the wreck of the last 
 particle are of a new kind. They are 
 
 portions of carbon, 
 portions of hydrogen, 
 portions of oxygen. 
 
 This last particle of sugar is separated into its ultimate 
 constituents only by chemical processes. This last particle 
 before it is broken up is called the molecule, the word mean- 
 ing a little portion. The single individual thing it refers to 
 cannot be detected by the eye, nor can it be in any way 
 appreciated except by scientific means. But a chemical 
 change of the last multitude of molecules at once, is practica- 
 ble to every body, and it is to a certain extent recognized by 
 every one who heats sugar until it turns to a charred mass. 
 This charred mass is mainly carbon one of the components 
 of the now ruined sugar and it is very unlike sugar in every 
 
THE CONSTRUCTION OF SUBSTANCES. 37 
 
 way. The chemist can show that when sugar is charred the 
 oxygen and the hydrogen go off mostly in the form of gases 
 or vapors, and that on this account they escape detection at 
 the hands of all ordinary observers. 
 
 The Chemical Use of the Term Atom. 
 
 It appears, then, that the chemist is able to subdivide 
 molecules into smaller parts. But he finds that in the pres- 
 ent state of our knowledge of matter further subdivision is 
 impracticable. He can take the oxygen out of the sugar, but 
 he cannot take anything but oxygen out of oxygen; he can 
 take hydrogen out of sugar, but he cannot take any thing but 
 hydrogen out of hydrogen ; he can take carbon out of sugar, 
 but he cannot take any thing but carbon out of carbon. 
 
 As a result of all chemical study of common sugar the 
 chemist has fixed upon the following as expressing most 
 closely the facts as he knows them : 
 
 The formula 
 of one molecule of pure cane sugar is 
 
 The chemical formula of any substance expresses much 
 more than the reader would at first imagine. Thus the for- 
 mula CigHgsOn conveys at once to the chemist a series of 
 facts, some of which may be amplified as follows : one mole- 
 cule of sugar contains three kinds of substance : carbon, 
 hydrogen and oxygen ; each of these kinds of matter exists 
 in the molecule in separate minute portions such as in the 
 present state of human knowledge are divisible only in a 
 limited way; thus the carbon of one molecule of sugar is 
 divisible into twelve parts, and no further ; 
 
 the hydrogen of one molecule of sugar is divisible 
 into twenty-two parts, and no further; 
 
 the oxygen of one molecule of sugar is divisible 
 into eleven parts, and no further. 
 
CHEMISTRY. 
 
 Definition of the Term Atom. 
 
 Now at last the atom has been reached. It is that portion 
 of any kind of matter that is to human beings for the 
 present, at least indivisible in fact. It has already been 
 stated that there are only about seventy different kinds of 
 atoms; it appears, then, that there are only seventy kinds of 
 matter that at present cannot be chemically subdivided 
 into different components. 
 
 It is true that some persons consider that certain intricate 
 chemical processes suggest that what have been here called 
 indivisible atoms are themselves really capable of yet further 
 decomposition. Without attempting here to sustain or to 
 demolish this proposition, or to say what the future of chemi- 
 cal investigation may reveal, it may be safely remarked that 
 adequate proof has not yet been offered of the ability of any 
 one to successfully accomplish a decomposition of the atoms 
 enumerated.* 
 
 Plainly, then, just as bricks may be made into a building, 
 and a series of buildings may make a city, and a series of 
 cities may exist in a State, so atoms may combine together 
 to form molecules, and molecules may cohere together to 
 form a mass, and visible masses may be placed side by side 
 and give rise to the ordinary objects recognized about us. 
 True, the comparison suggested is not strictly carried out in 
 all particulars. But the difficulty is not a serious one ; for 
 a city might contain a multitude of houses each one so 
 similar that no difference could be distinguished between 
 them, just as a mass of sugar does in fact contain molecules 
 of which each one is so like its neighbor that the most 
 refined chemical methods discover no difference between 
 them. Again, these same houses might be composed 
 of combinations of brick and other materials differing 
 among themselves, but closely corresponding in every house. 
 So the molecule of sugar does contain certain atoms of car- 
 bon, hydrogen and oxygen, the atoms of one kind differ- 
 
 * See references (on page 19) to suggestions that our so-called elements are in fact 
 compound. 
 
THE CONSTRUCTION OF SUBSTANCES. 39 
 
 ing distinctly and absolutely from the atoms of the other 
 kind. 
 
 But here the parallelism seems to cease. For while all 
 bricks and other components of a building are capable of 
 being split into smaller portions, the atoms composing the 
 molecule are found by the chemist to be absolutely indivis- 
 ible, in the present state of knowledge. 
 
 Employing still further the illustration already in hand it 
 maybe added that just as the walls of a dwelling might con- 
 tain bricks either of the same kind as to their color, shape 
 and weight, or else differing in these or other respects, so a 
 molecule may be a little group of atoms of the same kind, or 
 it may be a group of atoms of different kinds. Thus the 
 hydrogen gas molecule is composed of two atoms each just 
 alike, and each being hydrogen. This molecule is represented 
 
 by the formula 
 
 H, or H H. 
 
 So a molecule of chlorine gas is composed of two atoms 
 each just alike and each being chlorine. This molecule is 
 represented by the formula 
 
 Cl a or Cl Cl. 
 
 Everything Built up of Atoms. 
 
 Now each of the elementary substances has molecules 
 composed of atoms, and each molecule of a given element is 
 composed of atoms of the same kind. And further all the 
 vast and countless myriad of compound substances, whether 
 buried in the heart of the solid earth, whether drifting in the 
 wandering courses of the ocean's currents, whether floating 
 in the airy mass which is wrapped about our globe, whether 
 components of distant planets all these substances are con- 
 structed, so far as we know, of inconceivably minute atoms 
 of varying kinds bound together by chemical attraction into 
 molecules, the molecules being piled one upon another into 
 those masses whose reaction our dull senses can appreciate. 
 It may be that our great central luminary, the sun, has its 
 atoms combined in molecules also. Perhaps, however, the 
 
40 CHEMISTRY. 
 
 intense heat of that seething mass which pours its volcanic 
 torrents millions of miles out from the surface is sufficient to 
 keep in a state of decomposition molecules such as we know 
 here, and even the elementary atoms which are at present 
 undecomposable by our processes. 
 
 Atoms and Molecules Manifest Chemical Affinity. 
 
 But, to the chemist, atoms, molecules and masses possess an 
 interest of another kind. Each atom and each molecule is 
 endowed with an invisible, occult power called chemical 
 affinity. This power acts like an unseen spirit possessed of 
 likes and dislikes. By reason of it an atom of hydrogen, 
 for example, instantly binds itself to an atom of chlorine 
 whenever opportunity offers, but will never, even under the 
 most favorable circumstances, combine with an atom of gold. 
 
 Finally, this attractive force is a kind of energy of which 
 no true explanation can be offered. All that human beings 
 can do is to attentively study it as it manifests itself in the 
 relations of elementary substances and compound substances 
 one toward another. Indeed one of the principal offices of 
 chemistry is to study these relationships as they develop. It 
 is the multitude of possible relationships and actions of which 
 the numberless substances known are capable that gives to 
 chemistry its great scope and variety, and that makes it such a 
 vast field for experiment, for discovery of facts, and for 
 industrial application of them. 
 
 READING REFERENCES. 
 Atoms and Molecules. 
 
 Barker. G. P. Amer. Chemist. Nov. 1876. vii, p. 164. 
 Stoney, Johnstone. Phil. Mag. xxxvi, p. 132. 
 Clerk-Maxwell, J._ Encyclopedia Britannica, article Atoms. 
 
 Theory of Heat. New York. 1872. 
 Thomson, Sir Wm. Nature. Mch. 1870. 
 
 Tait, P. G-. Recent Advances in Physical Science. London 1876. p. 283. 
 Mayer, A. M. Lecture Notes on Physics, p. 52. 
 Cooke, J. P. The New Chemistry. New York. pp. 29-43. 
 American Cyclopedia, article Molecule. 
 
HOW CHEMICAL AFFINITY WORKS. 41 
 
 VIII. 
 
 HOW CHEMICAL AFFINITY WORKS. 
 
 l|T is an interesting fact that elements and compounds 
 manifest an exceedingly great variety of tenden- 
 cies to combination. Fragments of matter, so 
 small that no eye perceives them, have, wrapped up 
 in themselves, a multitude of determinate powers. A given 
 atom, as of lead for example, will very readily combine with 
 oxygen and with some other substances, but it seems to abso- 
 lutely refuse to combine with nitrogen. So hydrogen will com- 
 bine very readily with chlorine and with many other elements, 
 but it refuses to form any union with silver and with many 
 other elementary substances. It cannot be called a whim that 
 determines the kind of element or its amount that a certain 
 substance will combine with, though the likes and dislikes of 
 atoms are in this respect exceedingly marked and even incom- 
 prehensible. But however impossible it may be to explain 
 an element's friendly or unfriendly deportment toward 
 another, it is possible in each case to learn the facts with cer- 
 tainty ; for each atom possesses its true individuality, and is 
 always constant and consistent in its affinities and hates. 
 
 It is the purpose of this chapter to present in an orderly 
 manner some of the peculiarities of this mysterious power of 
 chemical affinity. 
 
 First. Each Kind of Atom Has Its Peculiar 
 Chemical Affinities, 
 
 Chemical affinity seems to reside within the atom as a per- 
 manent, ever present and guiding energy. Thus while iron 
 oxidizes readily that is, manifests under a multitude of com- 
 mon conditions a willingness to combine with oxygen and 
 form a new compound called oxide of iron, and well known 
 under the name of iron-rust gold, on the other hand, oxidizes 
 
42 CHEMISTRY. 
 
 unwillingly ; indeed in order to get it to combine with oxygen 
 it must be coaxed by means of circuitous and carefully planned 
 devices. But these atoms are always consistent in their 
 action, for iron under any and every condition oxidizes more 
 readily than gold does. 
 
 Second. Chemical Affinity Acts Only Under Favor- 
 able Conditions. 
 
 While chemical action often works with most intense energy 
 it does so only when certain outside and incidental conditions 
 are favorable. Thus carbon has under certain conditions an 
 affinity for oxygen, and manifests its tendency to combination 
 with an intensity that is scarcely surpassed. In order, how- 
 ever, to awaken and vivify the dormant inclination it must be 
 stimulated by certain definite and favorable conditions. The 
 most important of these conditions is a certain amount of 
 warmth. The stores of fuel in our cellars the coal and the 
 wood and all other combustible things are surrounded by 
 great quantities of oxygen, w r hich winds its way, with every 
 slightest stir of the mobile air, in and out through all the 
 crevices that the fuel affords, passing continually in the 
 immediate neighborhood of ample quantities of atoms of 
 carbon. But it does not ordinarily unite with them. Sub- 
 ject the whole or any portion of these combustible things to 
 a, slight rise in temperature then the atoms of oxygen and 
 the atoms of carbon seem to arouse themselves from repose : 
 they unite in friendly and firm grasp, and what is called 
 chemical union takes place. 
 
 To the ordinary observer the heat that is produced is the 
 most notable sign of this kind of combination. The chemist, 
 however, discovers a yet more conclusive evidence, for he 
 finds that several kinds of new molecules have been produced ; 
 one of these kinds, for example, is expressible by the name 
 carbon dioxide and by the formula CO 2 . Evidently this for- 
 mula means that each atom of carbon has united with two 
 atoms of oxygen. In this familiar example heat is the agency 
 
HOW CHEMICAL AFFINITY WORKS. 43 
 
 that stimulates the atoms to a display of the chemical force 
 that previously was slumbering within them. 
 
 Light, and the electric current, and the vital forces of ani- 
 mals and plants, though acting in a manner less familiar to us, 
 are energizers of chemical affinity, and all have their proper 
 influence to make atoms join in union ; indeed in some cases 
 they make atoms burst from each other's bonds and fly away 
 to more congenial conditions. 
 
 Third. Each Atom Has Certain General Numer- 
 ical Preferences. 
 
 The chemist also recognizes each atom as possessing certain 
 peculiar numerical preferences in its combinations ; a mani- 
 festation of chemical affinity called equivalence, or atom-fixing 
 power. Thus when carbon burns in a stove, by reason of the 
 air passing by it on the w r ay to the chimney, it seizes upon 
 some of the oxygen atoms and binds a definite number of 
 them to itself. If there is much air, each atom of carbon, of 
 the millions present, picks out two atoms of oxygen from the 
 air ; if there is but little air, each atom of carbon has 
 to be satisfied with one atom of oxygen. Now in these two 
 cases, of course, different substances are formed. The first, 
 whose composition is represented by the formula CO 2 , has 
 already been spoken of as carbon dioxide. To the other, 
 whose composition is represented by the formula CO, is ap- 
 plied the name carbon monoxide. Here, then, we see that 
 the same atom may sometimes combine with two atoms of 
 oxygen and sometimes with only one. 
 
 Further, the chemist knows four simple and familiar com- 
 pounds whose molecules illustrate very strikingly the differ- 
 ence of equivalence of different atoms. These compounds are 
 the following : 
 
 Hydrochloric acid (Hydric chloride), HCI or H Cl 
 
 IT- ) 
 Water (Hydric oxide), H 2 or J- 
 
44 CHEMISTRY. 
 
 Ammonia gas (Hydric nitride), 
 
 H-) 
 
 H 3 X or H J. S 
 H-J 
 
 H-] 
 
 Marsh gas (Hydric carbide), H 4 C or H I 
 
 H 
 H 
 
 It has been found advisable to adopt the atom of hydro- 
 gen as the standard of equivalence or atom-fixing power. 
 It is plain that by this method of comparison the atom 
 chlorine may be said to have the equivalence one, since it 
 combines with one atom of hydrogen. And so the atom 
 oxygen may be said to have the equivalence two, since it 
 combines with two atoms of hydrogen. And the atom 
 nitrogen may be said to have the equivalence three, since it 
 combines with three atoms of hydrogen. And the atom 
 carbon may be said to have the equivalence four, since it 
 combines with four atoms of hydrogen. 
 
 The language of chemistry sometimes presents the same 
 observed facts, in a slightly different form, somewhat as fol- 
 lows: Chlorine is said to have one point of attraction and is 
 called a monad (a term derived from the Greek word \iovdc, 
 monas, a unit). Oxygen is said to have two points of 
 attraction and is called a dyad (a term derived from the 
 Greek word 6v dg, clyas, two). Nitrogen is said to have three 
 points of attraction and is called a triad (a term derived 
 from the Greek word rotdg, trios, a group of three). Car- 
 bon is said to have four points of attraction and is called a 
 tetrad (a term derived from the Greek word rrTpdg, tetras, 
 four). 
 
 While hydrogen as the basis of the system has the uniform 
 equivalence one, and is always a monad, and oxygen its close 
 friend and ally lias always the equivalence two, and is 
 always a dyad, most other elements have some variety of 
 equivalence. Thus chlorine has at different times different 
 equivalences, sometimes one, sometimes three, or five, or 
 seven. So nitrogen has at different times the different 
 
HOW CHEMICAL AFFINITY WORKS. 45 
 
 equivalences, one, three, Jive. So carbon has sometimes an 
 equivalence two, sometimes four. 
 
 Fourth. Each Atom Has Certain Special Numer- 
 ical Preferences. 
 
 Careful experiment has shown that the elementary sub* 
 stances unite in fixed proportions by weight. Thus one 
 ounce of hydrogen unites with almost exactly thirty-five and 
 a half ounces of chlorine to form hydrochloric acid; and one 
 ounce of hydrogen unites with almost exactly eighty ounces 
 of bromine to form bydrobromic acid; and one ounce of 
 hydrogen unites with almost exactly one hundred and twenty- 
 seven ounces of iodine to form hydriodic acid. 
 
 Again, twenty-three grains of sodium unite with thirty- 
 five and a half grains of chlorine to form sodic chloride; 
 and twenty-three grains of sodium unite with eighty grains 
 of bromine to form sodic bromide; and twenty-three grains 
 of sodium unite with one hundred and twenty-seven grains 
 of iodine to form sodic iodide. 
 
 Now these numbers 
 
 1. for hydrogen, 
 
 23. " sodium, 
 
 35.5 " chlorine, 
 
 80. " bromine, 
 
 127. " iodine, 
 
 are fixed and constant numbers, and are largely used in 
 chemical computations. 
 
 They are called combining numbers, for such indeed they 
 are; they are also called atomic weights, and they are sup- 
 posed to represent the relative weights of single atoms of the 
 substances mentioned. 
 
 Careful chemical study of the way in which atoms 
 combine has developed the following as a fundamental law 
 of nature. In the same chemical compound there are always 
 the same kind and number of elementary atoms, and these 
 
46 CHEMISTRY. 
 
 atoms are united in fixed proportions by weight. This law 
 is a formal statement of facts similar to those just referred 
 to in this and the preceding topic. It does not therefore 
 seem to call for further explanation at this point. 
 
 Fifth. Chemical Changes Neither Create nor 
 Destroy Matter. 
 
 When chemical changes are produced by reason of the 
 action of chemical affinity, there is never either gain in 
 weight or loss in weight. In other words there is no 
 creation of matter and no destruction of it. In former 
 times, people who observed the disappearance of solid mat- 
 ter when charcoal burns thought that the substance was 
 destroyed partly if not wholly. The modern chemist finds, 
 however, that the carbon is only turned into the form of an 
 invisible gas, and that by the use of appropriate appliances 
 he can find the weight of this gas and compare it with 
 that of the carbon producing it. In the combustion of car- 
 bon the chemical change is represented by the following 
 equation : 
 
 C + 2 C0 2 
 
 One atom of Two atoms of One molecule of 
 
 Carbon Oxygen Carbon dioxide. 
 
 12 32 44 
 
 parts by weight. parts by weight. parts by weight. 
 
 44 44 
 
 This equation means that the chemist has discovered, by 
 careful experiments, that when any twelve parts by weight 
 of carbon say twelve pounds are completely burned, they 
 always unite with thirty-two corresponding parts of oxygen 
 (in this case thirty-two pounds), and they produce forty-four 
 parts by weight of carbon dioxide (in this case forty-four 
 pounds). 
 
 And so in all chemical changes; the substances taking part 
 whether solid, liquid or gaseous may be weighed, and the 
 
110 W CHEMICAL AFFINITY WORKS. 47 
 
 sum of the weights of all the matters finally produced is 
 just equal to the sum of the weights of the original factors. 
 
 Sixth. Chemical Changes Produce Striking 
 Results. 
 
 So far as our present knowledge goes each of the atoms 
 appears to be fixed and unchangeable and to possess through 
 all its varied combinations an inherent character which 
 belongs to it, and which no human being at present knows 
 how to alter. It is true, however, that the opinion seems to 
 be gaining ground that the elementary atoms are probably 
 themselves compounds whose parts are very firmly bound 
 together ; compounds which may in future be decomposed. 
 Whatever may be the truth on this subject, it is recognized 
 that when the atoms at present accepted as elementary unite to 
 build up either simple or complex molecules, the various orig- 
 inal atomic characters are so blended and balanced and re-en- 
 forced as to afford in the molecular product an entirely new 
 and unexpected set of properties. An example of this latter 
 fact is found in the union of copper, sulphur, oxygen and 
 hydrogen. These substances may combine to form a mole- 
 cule which is called cupric sulphate, which has the compo- 
 sition expressed by the formula 
 
 CuS0 4 5H 2 0. 
 
 Of the constituents of this molecule, copper is red, sulphur is 
 yellow, oxygen is colorless, hydrogen is colorless ; but when 
 they unite the cupric sulphate formed is blue that is, its color 
 is not that of either of its constituents, nor is it intermediate 
 between them. There is simply a new and unexpected result, 
 and one which in the present state of knowledge cannot be 
 explained; it can merely be recorded. And this example is 
 only one of a myriad. Throughout nature chemical changes 
 most marked and to human thought unexpected arise from 
 the union of familiar elementary substances. 
 
48 CHEMISTRY. 
 
 Seventh. Chemical Changes are Often Attended by 
 Displays of Force. 
 
 In many chemical changes the union of the atoms is 
 attended with the production of heat, or electricity, or some 
 other form of energy. Now it is a law derived from mod- 
 ern discoveries that the amount of energy given out by any 
 chemical union is fixed and invariable, and that it is just the 
 same in amount as the quantity of that kind of energy that 
 is absorbed when such chemical action is reversed. 
 
 The Modern Atomic Theory. 
 
 The same chemical study which has developed the truth 
 of the facts already stated in this chapter has also given rise 
 to the modern atomic theory. The chemist is constrained to 
 believe that matter is composed of ultimate particles, as yet 
 undivided, called atoms. While these atoms are invisible to 
 mortal eye, even with the help of the finest known optical 
 appliances, yet when their existence is once admitted this 
 admission affords an explanation that is a satisfactory one, 
 and indeed the only one that harmonizes with the multitude 
 of observed chemical and physical laws. 
 
 This atomic theory, in its essential features, was suggested 
 in the early part of this century by Dr. John Dalton, who 
 was a teacher of mathematics in Manchester, England, and 
 who died as recently as in 1844. Dalton found recreation in 
 chemical experiments, and the mathematical turn of his mind 
 led him to express the results of his chemical analyses in a 
 new numerical form. Thus, previous to his time, it had been 
 customary to express the composition of all substances in 
 the ordinary percentage form. Now Dalton found that 
 when some special weight is adopted as the unit a variety of 
 previously concealed facts are revealed. The idea to be here 
 conveyed is partially, but perhaps sufficiently, expressed by 
 the following examples derived from the two compounds of 
 carbon already referred to: 
 
FIG 3.-John Dalton. Born at Eaglesfleld, England, Sept. 5, 1766 ; died July 27, 1844. 
 
 (49) 
 
50 CHEMISTRY. 
 
 Composition of the Two Compounds of Carbon and 
 Oxygen. 
 
 EXPRESSED IN PER CENTS. 
 
 Carbon Monoxide (CO). Carbon Dioxide (COJ. 
 
 Carbon, 43 per cent. 27 per cent. 
 
 Oxygen, 57 per cent. 73 per cent. 
 
 100 100 
 
 EXPRESSED IN DALTON'S FORM. 
 
 Carbon Monoxide (CO). 
 Carbon, 12 parts by weight. 
 Oxygen, 16 parts by weight. 
 
 28 
 
 Carbon Dioxide (CO^). 
 12 parts by weight. 
 32 parts by weight. 
 
 44 
 
 In Dalton's expression it is at once evident that, as com- 
 pared with the weight of carbon, the amount of oxygen in 
 carbon dioxide is exactly twice what it is in carbon mo- 
 noxide; but to the ordinary un mathematical mind the per cent- 
 age statement conceals this fact. Dalton's experiments with 
 still other compounds gave him results showing a simplicity 
 of relationships similar to that obtained from the carbon com- 
 pounds just referred to. To his mind these facts suggested 
 immediately the idea that an elementary substance is made 
 up of atoms each of a determinate weight, and that these 
 atoms combine by wholes and not by fractional parts, and 
 that although it is impossible to actually weigh any atom 
 separately, yet the weight ratios of a multitude of them that 
 combine as wholes express at once the weight ratios of the 
 atoms themselves. He thus got the idea of atomic weights 
 and constructed the first table of them. Since Dalton's first 
 
HOW CHEMICAL AFFINITY WORKS. 51 
 
 declaration of his atomic theory, the combining numbers of 
 the different atoms have been studied by chemists with the 
 most thoughtful care and the most painstaking methods 
 known to modern science; and tables have been constructed 
 showing the combining numbers which are believed also to 
 be the true atomic weights for all the various elements thus 
 far recognized. 
 
 READING REFERENCES. 
 
 Atomic Constitution of Bodies. 
 
 Saint-Venant. Jour, of Chem. Soc. of London, xxx, pt II, 472. 
 Atomic Philosophy. 
 
 Amer. Chemist, iii, 326. 
 
 Atomic Theory. 
 
 Williamson, A. W. (and others.) Jour, of Chem. Soc. of London, xxii, 
 328, 433. 
 
 Wurtz, Ad. The Atomic Theory. New York. 1881. 
 
 Atomic Volumes, Etc. 
 
 Avogadro. Annales de Chimie et de Physique. 3 Se'r. xiv, 330, 
 xxix, 248. 
 
 Atoms, Vortex Theory of 
 
 Thomson, Sir Wm. Phil. Mag. 1867. 
 
 Thomson, J. J. Science, iii, 289. 
 
 Tait, P. G. Recent Advances in Physical Sc'ence. London. 1876. 
 
 p. 283. 
 Atomic Weights, Dalton's First Table of 
 
 Roscoe, H. E. Chem. News, xxx, 266. 
 Chemical Operations, Calculus of 
 
 Brodie, B. C. Jour, of Chem. Soc. of London, xxi, 367. 
 Dalton, John 
 
 Henry, W. C. Life of Dalton. London. 1854. 
 Definite Proportions, Variability in Law of, 
 
 Boutlerow. Silliman's Journal. 3d Ser. xxvi, 63. 
 
 Cooke, J. P. loc. cit. 310. 
 
 Equivalents of the Elements. 
 
 Pumas, J. AnnaJes de Chiraie et de Physique. 3 Se'r. lv, 129. 
 
53 CHEMISTRY. 
 
 Energy. 
 
 Stewart, Balfour. The Conservation of Energy. New York. 1874. 
 Tait, P. G. Recent Advances in Ph} r sical Science. London. 187G. 
 Encyclopedia Britannica. vol. viii. 
 
 Gaseous and Liquid States of Matter. 
 
 Andrews, T. Jour, of Chem. Soc. of London, xxiii, 74; xxx, pt. Ii. 
 
 159. 
 Ramsey, W. Jour, of Chem. Soc. of London, xlii, 136. 
 
 Matter, Constitution of 
 
 Ditto, A. Annales dc Chimie et de Physique. 5 Ser. x, 145. 
 
 Nomenclature of Salts. 
 
 Madan, H. G. Jour, of Chem. Soc. of London, xxiii, 22. 
 
HYDROGEN. 53 
 
 IX. 
 
 HYDROGEN. 
 
 |HIS substance is one of the most interesting with 
 which the chemist has to deal. On account of its 
 chemical and physical properties, by reason of the 
 many important compound substances into which 
 it enters, by reason of the part it has played in the history of 
 chemical progress, it is entitled to a large share of the 
 student's attention. 
 
 Where Hydrogen is Found. 
 
 The name hydrogen was applied to it some time later than 
 the first recognition of the substance. The word is derived 
 from two Greek words^dwp, Injdor, water, and yewaw, gennao, 
 I form or produce), the word as a whole meaning water former. 
 In fact hydrogen is in all water wherever that substance 
 exists. That this is a very comprehensive expression appears 
 when it is remembered that the atmosphere always contains 
 water diffused through it in the form of invisible vapor even, 
 before that vapor is precipitated as the gentle dew, or the 
 crystalline snow, or the streaming rain. Again, water in 
 seas and oceans, lakes and livers, is the mantle of nearly 
 three fourths of the earth's surface. Every living being on 
 the dry land, whether animal or vegetable, contains large 
 quantities of water in its structure : the blood of the higher 
 animals is nearly eight tenths water. 
 
 While water is the principal substance containing hydro- 
 gen, this gas exists also as a constituent part of a great many 
 other solid and liquid matters found in the earth. 
 
 Why Free Hydrogen is not Found. 
 
 Hydrogen scarcely ever exists on our globe alone that is, 
 in the free or uncombined condition. Indeed there are cer- 
 
54 
 
 tain definite reasons why it should not. These are based 
 mainly upon the very strong chemical affinity that hydrogen 
 lias for oxygen. Now, as has been declared already, the 
 latter substance is the most abundant element in nature, and 
 it exists in very large quantities in our atmosphere. Spread 
 all over the surface of the earth, then, the free oxygen of the 
 air stands prepared to combine with hydrogen wherever the 
 latter may be liberated. Such combination might not occur, 
 it is true, unless initiated by influence of heat or some flame 
 of fire ; but owing to the constant agitation of the air by 
 reason of uniform currents like trade winds, as well as those 
 produced when the atmosphere is agitated by violent storms, 
 any mixture of hydrogen and oxygen would be likely soon 
 to come into contact with some flame or fire, and so these 
 components would enter into combination. Thus hydrogen 
 would not be likely to remain long uncombined even were it 
 produced in considerable quantity by natural terrestrial 
 operations. 
 
 The Discoverer of Hydrogen. 
 
 Hydrogen was first distinctly described, and its properties 
 as a special kind of gaseous matter clearly pointed out, in the 
 year 1766, by an English chemist, the Honorable Henry 
 Cavendish. This philosopher, the son of Lord Charles 
 Cavendish, and the grandson at once of the Duke of Devon- 
 shire and the Duke of Kent, is one of the most curious char- 
 acters in the history of the natural sciences. He was of an 
 exceptionally careful, thorough nnd pains-taking temper, 
 which well fitted him for those scientific pursuits which were 
 the prime objects of his thoughts. Sir Humphry Davy said 
 of him : " The accuracy and beauty of his earlier labors have 
 remained unimpaired amidst the progress of discovery, and 
 their merits have been illustrated by discussion and exalted 
 by time." 
 
 In addition to his possession of many special aptitudes for 
 the exact studies to which he devoted his entire existence, 
 it should be recognized that he lived at a period that was 
 
HYDROGEN. 55 
 
 remarkably favorable to the pursuit of the natural sciences. 
 The times, the state of knowledge, the condition of society 
 all over Europe seemed to be ripe for this kind of progress, 
 for in Scotland, in England, in France, in Germany, in Swe- 
 den, there then appeared experimenters of unsurpassed skill, 
 and chemistry as a science had then its birth under most for- 
 tunate auspices. 
 
 Cavendish was very peculiar in his manners and habits, 
 living in great seclusion and retirement and in the most sim- 
 ple and methodical manner ; indeed his oddities attained for 
 him the unenviable distinction of a place in a book devoted 
 to the lives of English eccentrics. In that work, as well as 
 in Dr. Wilson's life of him, are many amusing anecdotes of 
 his way of life. One most remarkable episode was his inherit- 
 ance of wealth. Though poor in his youth he was suddenly 
 made rich in middle life by a bequest whose origin is scarcely 
 known. M. Biot neatly described him as " le plus riche de 
 tous les savants, et probablement aussi le plus savant de 
 tons les riches." He lived on however in as great seclusion 
 as before, his chosen associates being his flasks and his ther- 
 mometers. His millions made no observable impression upon 
 his habits, notwithstanding at his death they had made him 
 the largest holder of the stock of the Bank of England. 
 
 Lord Brougham says that Cavendish probably uttered 
 fewer words in the course of his life than any other man who 
 ever lived to fourscore years, not at all excepting the monks 
 of La Trappe who were bound to perpetual silence except 
 in cases of absolute necessity. 
 
 Why Hydrogen was not Discovered Earlier. 
 
 Doubtless those prehistoric men, who in earliest days looked 
 about upon the face of the earth curiously examining their 
 heritage from the Creator, were familiar with water in its 
 various forms. They must have prized its bland and refresh- 
 ing powers and have learned many of its more important uses. 
 But the idea that it is made up of more than one kind of sub- 
 
FIG. 4.-Joseph Black, M.D. Born in Bordeaux, in 1728 ; died in Edinburgh, Nov. 2G, 1799. 
 
 (56) 
 
HYDROGEN. 57 
 
 stance or matter was not suspected until very recent times, 
 and not proved until the masterly investigations of Caven- 
 dish clearly set forth the facts. 
 
 The very idea of a chemical compound that is, of a sub- 
 stance as made up of inconceivably small portions of matter 
 in a union of almost inconceivable intimacy, an idea very 
 familiar to students of the present day probably did not enter 
 the minds even of those profound thinkers who suggested 
 the earlier atomic philosophies. In fact, our form of the 
 notion of chemical union is scarcely more than a century old. 
 
 Moreover, hydrogen is a gas, and the notion of gas is itself 
 decidedly a modern one. It was first stated in well-defined 
 form in the year 1752, by Dr. Joseph Black, professor in 
 Glasgow and Edinburgh. Black clearly and conclusively 
 demonstrated the existence of airs of a different kind from 
 that familiar to us in our atmosphere. It is true, Van Ilel- 
 innnt and even others, fully one hundred years before Black's 
 time, had known and stated more or less distinctly the exist- 
 ence of a gas or air different from that we breathe ; but 
 owing to a variety of circumstances these wonderful discover- 
 ies were allowed to lapse into forgetf'ulness. Thus the human 
 race lost for a century much advantageous knowledge; but 
 probably the general social advancement of those times had 
 not then prepared mankind for the benefits which the 
 development of modern chemistry has conferred upon the 
 present citizens of the world. 
 
 Again, experimenting with gases was not well understood 
 until about the year 17 TO, when Joseph Priestley invented 
 that contrivance for manipulating them known as the pneu- 
 matic trough, for which no better substitute has yet been 
 devised. 
 
 Further, in water which has already been referred to as 
 the most abundant and widely-diffused compound of hydro- 
 gen the partner elements are bound together by a chemical 
 affinity that cannot be readily overcome. This intensity of 
 attractive force between the constituent elements is thei'e- 
 fore another reason why the true composition of water was 
 
CHEMISTRY. 
 
 so long an unsolved riddle, and why hydrogen was not earlier 
 recognized as a thing or kind of matter by itself, although 
 in its principal compound one of the most admirable gifts 
 of the Creator to man it was well-known from the first days 
 of the human race. 
 
 How Hydrogen is Prepared. 
 
 Hydrogen may be obtained by the chemist in several ways : 
 
 First. There is a method of directly tearing the elements 
 
 composing water apart from each other. Considered the- 
 
 FIG. 5. Apparatus for decomposition of water, (by action of two cells of the Bunson 
 galvanic battery) and for collection of hydrogen and oxygen gases in separate receiv- 
 ers over the two electrodes of the battery. 
 
 oretically this process is a most direct and simple one. In 
 order to realize its results, however, advantage must be taken 
 of the galvanic current. This force may be obtained readily, 
 it is true : thus when two metals, dipped in a liquid, are con- 
 nected by a wire it is usually generated. But no one knows 
 fully what the current is. The words galvanic current and 
 voltaic current suggest the two investigators, Galvani and 
 Volta, who were the pioneers in this field, but they give 
 nothing that can be called an explanation of the wondrous, 
 invisible, imponderable form of energy referred to. It is a 
 
HYDROGEN. 50 
 
 force of an exceedingly interesting character and about which 
 a certain considerable body of knowledge has been collected. 
 
 Among the variety of facts known about it is that one 
 which relates to water; namely, when the poles, or electrodes, 
 of a suitable galvanic battery are dipped into a vessel of 
 water bubbles of gas may be seen to flow freely from each 
 of them. The gases may be collected in a vessel placed over 
 the electrodes, but the experimenter may well beware of in- 
 cautiously treating what has now been produced ; he has 
 obtained a mixture of oxygen and hydrogen from the orig- 
 inal water, and these elements, which he has rended apart 
 from their more intimate union, are ready upon the approach 
 of the smallest flame to rush into union again, with extraordi- 
 nary violence, and in such a way as to produce a tremendous 
 explosion. In the act of this explosion, therefore, water is 
 again produced, first as expansive vapor, then condensible 
 back to the liquid drops whence it came. 
 
 If however the product from each electrode is collected by 
 itself in a separate tube, the one gas is found to be very differ- 
 ent from the other. The one is found to be hydrogen, the 
 other oxygen. In accordance with the formula H 2 O which 
 it has before been stated represents the composition of water 
 the hydrogen is found to be given off in a bulk or volume 
 that is twice as great as that of the oxygen obtained at the 
 same time from the same amount of water. 
 
 Second. Hydrogen may be obtained by bringing into con- 
 tact with water, under proper conditions, certain substances 
 that have a very strong affinity for its oxygen and at the 
 same time but little affinity for its hydrogen. Now every 
 one is familiar with the fact that iron rusts readily in the 
 air. The chemist can demonstrate that this rust is a com- 
 pound of iron and oxygen. The union of these elements 
 under ordinary conditions suggests at once that that union 
 arises from an affinity between the iron and the oxygen. 
 This affinity is much greater at high temperatures, for it is 
 well known that iron rusts more violently when subjected to 
 heat. These facts, then, are made use of for the purpose of 
 
60 
 
 CHEMISTRY. 
 
 withdrawing oxygen from water and thus forcing the hydro- 
 gen out in the free or uncombined condition, so that it may 
 be obtained and experimented upon. 
 
 To produce hydrogen by this method there must be pro- 
 vided a long iron pipe which passes through a hot furnace; 
 the pipe should contain fragments of iron, such as iron turn- 
 ings, or iron filings, or pieces of iron wire. Then a current 
 of steam must be passed through the pipe. The iron be- 
 
 FIG. 6. Apparatus for preparation of hydrogen gas. Steam, ^enerated in the 
 small retort, is conveyed through the tube placed in the gas-furnace; iron turnings 
 within the tube being highly heated, decompose the water-vapor, which thereby 
 evolves hydrogen. The liberated gas is collected in the little bell-glass. 
 
 comes red hot, and under these circumstances manifests more 
 affinity for the oxygen of the steam than the hydrogen does. 
 The iron then grasps the oxygen and holds it fast. As a 
 result a peculiar kind of oxide of iron of a black color is 
 produced. Its chemical formula is Fe 3 O 4 , and it is cnlled by 
 chemists ferroso-ferric oxide. The iron has now taken the 
 place, as a partner of the oxygen, that the hydrogen formerly 
 had. The hydrogen is thus cast out from its combination 
 and is set free as an uncombined gas, in which liberated con- 
 dition it is expelled at the end of the tube. The chemical 
 action between the iron and the steam may be represented 
 by the following equation ; 
 
HYDROGEN. 61 
 
 Fe 3 
 
 r- 4H,0 
 
 Fe 3 4 -| 
 
 4H 3 
 
 Three atoms of 
 
 Four molecules of 
 
 One molecule of 
 
 Four molecules of 
 
 Iron, 
 
 Water, 
 
 Fcrroso-ferric oxide, 
 
 Hydrogen, 
 
 1G8 
 
 72 
 
 232 
 
 8 
 
 parts by weight. 
 
 parts by weight. 
 
 parts by weight. 
 
 parts by weight. 
 
 240 210 
 
 The gas produced as just described may bo collected by 
 adjusting a suitable tube in connection with the pipe con- 
 taining the iron. When the gas is examined it is found to 
 be in fact hydrogen. It will burn with a blue flame and 
 perform all the various actions that acknowledged hydrogen 
 will. 
 
 Third. There are other metals, not used in the ordinary 
 arts and trades but still familiar to the chemist, which have 
 far greater affinity for oxygen than iron has. The metal 
 called sodium is one of these. Its affinity for oxygen is so 
 great that it cannot be long preserved in the open air ; a 
 block or lump of it, if exposed to the air, gradually turns to 
 a mass of rust of sodium that is, oxide of sodium. This 
 metal, therefore, is preserved by the chemist in tightly closed 
 bottles or else under a layer of petroleum oil. The oil keeps 
 the air away from the metal; moreover the oil contains no 
 oxygen in its composition, as many other liquids do. This 
 metal, sodium, though heavier than the oil, is lighter than 
 water. If thrown upon water it floats. But, by virtue of 
 its intense affinity for oxygen, it at the same time decomposes 
 the water. It draws the oxygen to itself and it liberates the 
 hydrogen. Some chemical skill is requisite in the perform- 
 ance of this apparently simple experiment, for occasionally 
 the violent affinities involved set the sodium and the hydro- 
 gen on fire, and give rise to dangerous explosions. When 
 properly conducted, however, the hydrogen from this process 
 may be collected in a vessel and its various characteristics 
 displayed.* 
 
 Fourth. The most common way of producing hydrogen 
 is by bringing together sulphuric acid and zinc. 
 
 * Appleton's Young Chemist, Philadelphia, Cowperthwait & Co- pp. 26, 27, 28, 
 
62 
 
 CHEMISTRY. 
 
 The chemical change is represented by the following 
 equation : 
 
 Zn -f H 2 SO 4 ZnSO 4 + H 2 
 
 One atom of 
 
 Zinc, 
 65 
 
 parts by weight. 
 
 One molecule of 
 
 Sulphuric acid, 
 98 
 
 parts by weight. 
 
 One molecule of 
 
 Zinc sulphate, 
 161 
 
 parts by weight. 
 
 One molecule of 
 
 Hydrogen, 
 2 
 
 parts by weight. 
 
 163 
 
 163 
 
 The zinc has affinity for the compound radicle SO 4 , known 
 as the sulphuric acid radicle, and it is plain that by reason 
 of its affinities the zinc takes the place of the hydrogen or 
 the place which the hydrogen formerly held as related to 
 the sulphuric acid radicle, SO 4 and that the hydrogen, 
 
 ^ thereby left with- 
 
 O out any thing to 
 
 combine with, ap- 
 pears as a free and 
 uncombined sub- 
 stance. The hy- 
 drogen produced 
 by this method can 
 be readily collect- 
 ed and examined. 
 Perhaps it ought 
 to be stated that 
 neither of the proc- 
 esses thus far ex- 
 plained is likely 
 to yield hydrogen in an absolutely pure condition. The va- 
 rious substances used are likely themselves to contain, asso- 
 ciated with them, small amounts of other substances which 
 give some impurity to the gas evolved. 
 
 Powers and Properties Manifested by Hydrogen. 
 
 Hydrogen has been seen, from the explanation already 
 given, to be a gas. Down to within a few years it resisted 
 all attempts to liquefy it. Chemists submitted it to intense 
 
 FIG. 7. Apparatus for production of hydrogen by ac- 
 tion of sulphuric acid on zinc, and for collection of the 
 gas in a receiver. 
 
HYDROGEN. 63 
 
 cold and enormous pressure, and to both these influences at 
 the same time, but without avail. Within a few years, how- 
 ever, by use of ampler resources and contrivances for the 
 application of these condensing agencies, it has been brought 
 down to the liquid and perhaps even to the solid state. 
 
 As a gas it is colorless, odorless, tasteless. 
 
 Bulk for bulk, it is the lightest substance known in nature. 
 Thus a quart of atmospheric air, light as it is, weighs over four- 
 teen times as much as a quart of hydrogen. A cubic inch of 
 gold weighs more than two hundred thousand times as much 
 as a cubic inch of hydrogen. This lightness is properly 
 illustrated by inflating a soap bubble with hydrogen rather 
 than with air. When soap bubbles are filled with air they 
 fall, unless, indeed, carried upward by a temporary current; 
 but when filled with hydrogen they invariably rise with great 
 rapidity. By reason of this great lightness hydrogen was 
 formerly used for the inflating of balloons, but at the present 
 day illuminating gas is so much cheaper that the latter is 
 generally used, although it is much heavier than hydrogen. 
 
 Diffusive Power of Hydrogen Gas. 
 
 It is not inappropriate to call attention here to certain 
 interesting relations th.'it hydrogen manifests toward gases 
 and solids. Thus hydrogen possesses to a marked degree 
 that curious facility of passing into and permeating other 
 gases which is spoken of as its diffusive power. True, this 
 power is possessed by all gases to a certain extent; but in 
 rapidity of action none approach hydrogen. As early as 
 1825 a German chemist named Dobereiner announced his 
 observations of this power. He noticed that upon collecting 
 some hydrogen in a cracked jar, placed in a pneumatic trough, 
 the hydrogen leaked out into the air more rapidly than the 
 air went in. So that in fact the water of the \rough rose on 
 the inside of the jar. It has been since discovered that 
 when almost any two gases whatsoever, if only of different 
 densities, are separated by a partition having fine cracks or 
 
64 CHEMISTRY. 
 
 holes in it, the lighter gas always moves out into the heavier 
 one more rapidly than the heavier gas moves in. As hydro- 
 gen is the lightest of all, of course it diffuses into other gases 
 with the greatest rapidity. 
 
 In liquids hydrogen does not ordinarily dissolve in any 
 considerable quantity. 
 
 With solids, however, it displays some properties that are 
 well-nigh incredible. Thus it has a very curious aptitude 
 for passing into the very interior of certain solid metals. 
 The white, compact, solid metal palladium, although it has 
 no visible pores, has the power of swallowing up into itself, 
 in some mysterious way, nearly a thousand times its bulk 
 of this gas; and, again, a thin sheet of this same solid metal, 
 air-tight to all appearances, allows hydrogen to pass through 
 it as easily as a sieve does water. 
 
 The Most Interesting Chemical Property of 
 Hydrogen. 
 
 T5y all means the most interesting chemical property of 
 hydrogen is its power to unite with oxygen. When it does 
 so unite all the phenomena of combustion appear. These 
 phenomena are generally the production of heat, light, flame, 
 and the formation of some new chemical compound. So, then, 
 when hydrogen unites w r ith oxygen it burns, it gives out 
 light (although that light is of but feeble intensity), it gives 
 out an enormous quantity of heat, it forms an oxidized prod- 
 uct. This product is water, but water that owing to the 
 great heat of the combustion is raised to the form of invis- 
 ible vapor. When, however, a jet of hydrogen gas is burned 
 under a bright but cool bell-glass, the deposit of mist 
 quickly formed on the inside of the glass shows that the 
 vapor produced by combustion has now condensed on the 
 bell to minute liquid drops. 
 
 In the matter of the heat involved hydrogen has the dis- 
 tinction of being above every other substance. One pound 
 of hydrogen when burned under favorable conditions evolves 
 
PLATE II. Bottling natural mineral water. (See Chap. XVI.) 
 
HYDROGEN. 
 
 65 
 
 heat enough to raise tJrirty-four thousand, four hundred 
 and sixty-two pounds of water from zero centigrade to 
 one degree centigrade, or 
 nearly the same as from 
 32 degrees Fahrenheit 
 to 34 degrees Fahrenheit. 
 This expression of the calo- 
 rific power of hydrogen has 
 the same meaning as the 
 following more technical 
 one; namely, burning hy- 
 drogen affords thirty-four 
 thousand four hundred and 
 sixty-two thermal units. 
 Now carbon, a fuel which 
 nature has provided, ami 
 which is certainly admira- 
 bly fitted to 'be man's chief 
 combustible, yields but 
 eight thousand and eighty 
 thermal units of the kind 
 just referred to, and for 
 purposes of comparison it may be added that sulphur yield? 
 but two thousand two hundred and sixty thermal units. 
 
 FIG 8. A glass tube held over a hydrogen 
 flame, for the purpose of developing a mus- 
 ical note. 
 
 Hydrogen Cannot Supply the Uses of Atmos- 
 pheric Air. 
 
 Notwithstanding the remarkable evidences of chemical 
 affinity suggested by what has just been said, hydrogen can 
 in no sense act as a substitute for the atmospheric air. Thus, 
 it does not support animal life nor will it sustain the com- 
 bustion of a caudle. A living animal immersed in a room 
 full of hydrogen would be drowned in it; a burning candle 
 carried into such a chamber would be extinguished as if 
 dipped in water. In fact the comparison with drowning is 
 very proper, for in drowning a living animal the water does 
 5 
 
66 
 
 CHEMISTRY. 
 
 not chemically injure the organism; the hydrogen and the 
 water, in the cases supposed, have similar action in prevent- 
 ing both the animal and the taper from securing their supply 
 of oxygen. 
 
 Uses to Which Hydrogen May be Put. 
 
 Hydrogen as the elementary gas finds but few applications 
 in the arts. It is true that from what has been said it ap- 
 pears as if its wonderful calorific power might be utilized in 
 some of the arts where high temperatures are requisite. But 
 
 FIG. 9. Disposition of apparatus for the production of water, by combustion of dry 
 hydrogen in air. 
 
 the cost and difficulties attending its preparation, the liabil- 
 ity to loss during its storage, and the danger from explosion 
 while in actual use, these and other circumstances have led 
 even the skilled artisan to content himself in most cases with 
 other, though inferior, materials. 
 
 But if the reader has attentively followed the introductory 
 chapters of this work he must have perceived that hydrogen 
 is made of great service in many of the measurements em- 
 ployed by the chemist. It has been noted that it is used as 
 
HYDROGEN. 6 ? 
 
 the standard of equivalence or atom-fixing power. It has 
 been spoken of as the standard of atomic weif/ht, and from 
 what has appeared in the remarks upon its lightness it seems 
 that it has been properly adopted as the standard of density 
 j'or gases. 
 
 READING REFERENCES. 
 Cavendish, Henry. 
 
 Brougham, H. Lives of Men of Letters and Science, etc. p. 420. 
 Timbs, J. English Eccentrics, etc. p. 132. 
 Wilson, George. Life of Cavendish. London. 1851. 
 Clerk- Maxwell J. Electrical Researches of Hon. H. Cavendish. 
 Cambridge. 
 
 Black, Joseph. 
 
 Brougham, H. Lives of Men of Letters and Science, etc. London. 
 1845. p. 324. 
 
 Diffusion of Gases. 
 
 Graham, T. Elements of Chemistry. 2 v. London. 1850. i, 84. 
 Jour, of Chem. Soc. of London, xvii. 334. 
 
 Occlusion of Hydrogen by Palladium. 
 
 Graham, T. Jour, of Chem. Soc. of London, xxii, 419. 
 
C8 CHEMISTRY. 
 
 X. 
 
 BALLOONS. 
 
 ]HE remarkable lightness of hydrogen early sug- 
 gested the fitness of that gas for the inflation of 
 balloons. From the earliest ages men have desired 
 to navigate the air. The drudgery of land travel- 
 ing over hills and mountains, over marshes and streams, 
 through jungles and forests, has led men to prefer voyaging 
 even by sea. Thus the people of the United States crossed 
 the stormy Atlantic in large numbers long before they trav- 
 ersed the wilds of the American continent to the Pacific 
 coast ; and the early voyagers from New York to the Golden 
 Gate of San Francisco preferred the water way, though it led 
 them through an enormous distance and around the perilous 
 Cape Horn, rather than undertake the shorter course over 
 the Rocky Mountains. Even at a later date, the sea voyage 
 to Panama, and across the Isthmus, and again by water way 
 to San Francisco was the ordinary course, until Pacific rail- 
 roads created a land pathway from one side of the continent 
 to the other. So men, envying the bird in its flight through 
 the mobile air, have desired yet more to conquer its smooth 
 courses, just as their keels have found a sliding pathway in 
 the watery main. But no truly successful air-voyaging was 
 possible until about one hundred years ago. 
 
 Invention of the Balloon. 
 
 In the year 1783 two brothers, named Stephen MontgolHer 
 and Joseph Montgolfier,' succeeded in sending up into the 
 atmosphere the first air-ship worthy of the name. They lived 
 in France, at a little town named Annonay, situated about 
 forty miles south of Lyons, and at the junction of two small 
 streams whose clear waters flow into the Rhone. Here the 
 brothers carried on with increasing skill and success the manu- 
 
BALLOONS. 
 
 69 
 
 facture of paper, a business which their father had conducted 
 there before them, and which in fact is carried on by their 
 descendants of the same name even at the present day. The 
 brothersj Stephen and Joseph, were skillful mechanics, and 
 one of them, it is said, had studied Dr. Priestley's work on 
 " Different Kinds of Air." This seems to have led him to 
 
 
 I 
 
 FIG. 10. One of the balloons of the Montgolfler brothers. 
 
 the idea of nerial navigation. However that may be, it is a 
 matter of history that on the 5th of June, 1783, the two 
 brothers sent up from Annonay a balloon about thirty-five 
 feet in diameter. Naturally it was marie of paper, though 
 lined with linen. The ascensional power of this balloon was 
 due to a proportional lightening of the air within it by the 
 influence of heat. The heat was produced by the combustion 
 of a large quantity of chopped straw, and also from burning 
 wool previously saturated with a little alcohol. Probably 
 
70 CHEMISTRY. 
 
 the Montgolfier brothers did not then fully know why their 
 balloon ascended : they appear to have thought that it arose 
 because of the volumes of smoke that filled it. It is hardly 
 probable that either Stephen or Joseph Montgolfier thought 
 at that time of using hydrogen for their air-ship, notwith- 
 standing its extraordinary lightness had been a matter of 
 public scientific knowledge for six or seven years. This mny 
 seem the more strange in view of the admitted fact that as 
 early as 1767 Dr. Black, of Edinburgh, had publicly demon- 
 strated that a suitable vessel filled with hydrogen would 
 ascend in the atmosphere as cork does in water. Of course 
 they did not think of employing illuminating gas, because 
 that substance was not then in public use. 
 
 The First Balloon Ascension in Paris. 
 
 The news of the wonderful and successful experiment at 
 Annonay was quickly sent to Paris, where it produced a 
 profound sensation. The interest extended from scientific 
 men to the royal family and the court, and indeed to the 
 entire population of the capital. For the French people 
 perhaps even more than other nations of Europe seern to 
 have been particularly interested at this time in the study 
 of chemical and physical science. The king instantly issued 
 a summons for the Montgolfiers to come to Paris. But the 
 Parisians could not even await their arrival. The scientists 
 of the capital, though but partially informed as to the char- 
 acter of the experiments performed at Annonay, at once set 
 to work. They decided upon hydrogen gas as probably the 
 best fitted for their purposes. Whereupon they filled a glob- 
 ular balloon with this gas, nnd prepared to try it in public 
 upon the Champ- de-Mars. It is said "that three hundred 
 thousand people that is, nearly half the population of Paris 
 gathered together, crowding every adjacent avenue, to 
 witness the unparalleled undertaking. The liberation of the 
 aerial messenger was announced to the public by a salvo of 
 artillery. The balloon immediately shot upward and, pierc- 
 
BALLOONS. 
 
 71 
 
 ing the clouds, was soon lost to view. When afterward it 
 slowly descended it reached the ground some fifteen miles 
 from Paris. Here a troop of peasants who detected the 
 strange apparition were at first struck with alarm, but 
 quickly rallied, attacked the monster and, of course, soon re- 
 duced it to shreds. The whole chain of circumstances 
 created so much excitement that the Government thought 
 proper to issue a proclamation upon the subject. A copy of 
 this interesting document is here presented in its original 
 form. Perhaps some readers will find the accompanying 
 translation acceptable : 
 
 French Proclamation Respecting Balloons. 
 
 Avertissement au people sur I'en- 
 levement des baltons ou globes en 
 
 On a fait une decouverte dont 
 le gouvernement a juge convena- 
 ble de donner connaissance, afin 
 de prevenir les terreurs qu'elle 
 pourrait occasioner parmi le peu- 
 ple. En calculant la difference 
 de pesanteur entre 1'air appele 
 inflammable et 1'air de notre at- 
 mosphere, on a trouve qn'un bal- 
 lon rempli de cet air inflamma- 
 ble devait s'elever de lui-meme 
 dans le ciel jusqu' au moment oh 
 les deux airs seraient en equili- 
 bre, ce qui ne peut etre qu' a une 
 tres grnnde hauteur. La prem- 
 iere experience a ete faite a An- 
 nonay, en Vivarais, par les sieurs 
 Montgolfier, iriventeurs. Une 
 ji'lobe de toile et de papier de 
 cent cinq pieds de circonference, 
 rempli d'air inflammable, s'eleva 
 lui-meme a une hauteur qu' on n' 
 a pu calculer. La meme expe- 
 rience vient d'etre renouvelee a 
 Paris, le 27 aout a cinq heurs du 
 
 Notice to the public relative to the 
 ascension of balloons or globes into the 
 
 A 'discovery lias been made to which 
 the Government considrs it adviseable 
 to call public attention, with a view 
 of preventing alarms which it other- 
 wise might occasion among the people. 
 Upon calculating the difference of 
 weight between the gas called in- 
 
 flammable air and 
 atmosphere it has 
 
 the air of our 
 been discovered 
 
 that a balloon filled with this in- 
 flammable air ought to rise of itself 
 to a height in the sky such that the 
 air within and that without will be 
 in equilibrium, a condition which will 
 not be reached except at a very great 
 elevation. The first experiment of this 
 sort has been made at Annonay, in 
 Vivarais, by the Messrs. Montgolfier, 
 the inventors. A globe of cloth and 
 paper one hundred and five feet in 
 circumference and filled with inflam- 
 mable air rose of itself to a height 
 which the observer could not calcu- 
 late. The same experiment has just 
 been repeated at Paris on the 27th 
 
CHEMISTRY. 
 
 soir, en presence d'un nombre in- 
 fini de personnes. Un globe de 
 taffetas enduit de gomme elas- 
 tique, de trente-six pieds de tour, 
 s'est eleve du Champ de-Mars 
 jusque dans les nues, oh on 1'a 
 perdu de vue. On se propose de 
 repeter cette experience avec des 
 globes beaucoup plus gros. 
 
 Chacun de ceux qui decouv- 
 riront dans le ciel de pareils 
 globes, qui presentent 1'aspect de 
 la lune obscurcie, doit done etre 
 preveuir que, loin d'etre uu phe- 
 nomene effrayant, ce n'est qu'une 
 machine tou jours composee de 
 taffetas ou de toile legere re- 
 couverte de papier, qui ne pent 
 causer aucuu mal, et dont il est 
 a presurner qu'on fera quelque 
 jour des applications utiles aux 
 besoins de la societe. 
 
 Lu et approve, 
 ce 3 septembre, 1783. 
 
 DF SAUVIGNY. 
 
 of August at 5 o'clock in the afternoon, 
 in presence of a vast number of per- 
 sons. A sphere of taffeta coated with 
 gum elastic, thirty-six feet in circum- 
 ference, ascended from the Champ- 
 de-Mara even to the clouds, in which 
 it became lost to sight. It is contem- 
 plated repeating this experiment with 
 very much larger globes. 
 
 Any one who discovers in the 
 sky globes of this sort, which present 
 the appearance of the moon when 
 slightly obscured, may therefore be 
 warned that, far from being an 
 alarming phenomenon, this is nothing 
 but a machine always constructed 
 of taffeta or of light cloth covered 
 with paper, which cannot do any 
 injury, and which it is thought 
 will assume at some future time 
 a form, that will prove useful to the 
 public. 
 
 Read and approved, 
 September 3, 1783. 
 
 DE SAUVIGNY. 
 
 The enthusiasm created by the original experiment of the 
 Montgolfier brothers led soon after to the election of both 
 of them to the Academy of Sciences. Moreover their inven- 
 tion was not allowed to rest long in its original form. 
 
 As early as November of the same year, 1783, two French 
 gentlemen had the courage to risk their lives in an ascension 
 from Paris in a balloon of the Montgolfier construction. 
 They floated freely away and made their landing in safety. 
 One of them, however, De Rozier by name, on a later occa- 
 sion attempted to cross the Channel in a double balloon one 
 part containing hydrogen, the other heated air in the Mont- 
 golfier style but at a great altitude the hydrogen balloon 
 took fire from the other, and De Rozier and his companion 
 were dashed to pieces on the rocks of the French coast. 
 Since that early rash attempt thousands of interesting and 
 
8? 
 
 S 
 
 : .- i : ? 
 
 fi ! S 
 S 1 1 1 J1J 
 
FIG. 11. Gay-Lussac and Biot making their balloon ascension for scientific observations In 
 
 (73) 
 
74 CBEMIST&Y. 
 
 safe balloon ascensions have been made, and increased 
 knowledge of the scientific principles has largely contributed 
 to the pleasure and comfort of the aeronaut. Yet the con- 
 trivance has been in most cases little more than a scientific toy. 
 
 The atmospheric air has thus far baffled the inventive 
 power of man to such an extent that the balloon as a me- 
 chanical contrivance has been subjected to but few decided 
 improvements since the Montgolfiers' first experiments, and 
 ascensions have afforded comparatively meager scientific or 
 other results. Indeed the most of them have been conducted 
 for personal gratification or popular entertainment. 
 
 Of course there are marked exceptions. Thus on the 24th 
 of August, 1804, two of the youngest but most distinguished 
 of French physicists, Messrs. Gay-Lussac and Biot, made an 
 important ascension. Their voyage was upon the suggestion 
 of the French Academy of Sciences, and they were well 
 equipped with apparatus for making observations. Their 
 results, particularly in magnetism, showed the same laws 
 prevailing in the higher air as upon the earth. But as there 
 were afterward expressed some doubts as to the accuracy of 
 these observations, Gay-Lussac made a later and higher 
 ascent alone. On the 16th of September he attained an alti- 
 tude of twenty-three thousand feet, the greatest reached up 
 to that date. His experiments on this occasion verified 
 those made before. Of particular interest was his test of 
 the composition of the atmosphere. The bottle of air col- 
 lected at this great height was found upon analysis to pos- 
 sess the same proportional amounts of oxygen and nitrogen 
 as that collected at the surface of the earth.* 
 
 * Of Gay-Lussac and this ascension there is told a pretty tale, which I will not mar 
 by making a translation : 
 
 " Parvenu a la hauteur de 7000 metres, il voulut, dit-il, essayer de monter plus haut. 
 et se de"barrassa de tous les objets dont il pouvait rigoureusement se passer. Au nom- 
 ber de ces objets flgurait une chaise en bois blanc, que le hasard fit tomber sur un 
 buisson, tout pres d'une jeune fllle qui gardait les moutons. Quel ne fut pas re"tonne- 
 ment de la bergere! Comme eut dit Florian. Le ciel e"tait pur, le ballon invisible. 
 Que penser de la chaise, si ce n'est qu'elle provenait du paradis ? On ne pouvait ob- 
 jecter a cette conjecture que la grpssierete du travail : les ouvriers, disaient les incred- 
 ules, ne pouvalent la-haut etre si inhabiles. La dispute en etat la, lorsque les jour- 
 naux, en publiant toutes les particuliarites du voyage de Gay-Lussac, y mirent fln, en 
 rangeant parmi les effets naturels ce qui jusqu' alors avait parut un miracle." 
 Arago; Eloge de Gay-Lussac. 
 
BALLOONS. 75 
 
 The height of this ascent has since been surpassed by 
 Messrs. Glaisher and Cox well, of England, who on Septem- 
 ber 5, 1862, attained an altitude of about thirty-seven thou- 
 sand feet. 
 
 Recent Use of Balloons. 
 
 Hydrogen is the lightest substance known, and this con- 
 sideration tends to make it a particularly favorable one for 
 the inflation of balloons. But we have seen that it was not 
 until after the Montgolh'er experiments that hydrogen came 
 into considerable use for this purpose. Hydrogen is still 
 occasionally prepared for purposes of this sort. It is then 
 produced by the action of sulphuric acid upon zinc. The 
 equation, already given, explaining this action is as follows: 
 
 Zn -f H 2 SO 4 ZnSO 4 + H 2 
 
 One atom of One molecule of One molecule of One molecule of 
 
 Zinc, Sulphuric acid, Zinc sulphate, Hydrogen, 
 
 65 98 161 2 
 
 parts by weight. parts by weight. parts by weight. parts by weight. 
 
 163 163 
 
 In case zinc is not at hand, iron-turnings have been made 
 to answer the same purpose; and the chemical change in this 
 event is represented by an equation of very similar form: 
 
 Fe 
 
 + H 2 S0 4 
 
 = FeSO 4 
 
 h H 2 
 
 One atom of 
 
 One molecule of 
 
 One molecule of 
 
 One molecule of 
 
 Iron, 
 
 Sulphuric acid, 
 
 Ferrous sulphate, 
 
 Hydrogen, 
 
 56 
 
 98 
 
 152 
 
 2 
 
 parts by weight. 
 
 parts by weight. 
 
 parts by weight. 
 
 parts ' w ight. 
 
 154 154 
 
 Both of these methods of producing hydrogen are still 
 somewhat used where balloons have to be inflated at points 
 distant from a city gas supply. But ihe manufacture of illu- 
 minating gas is now so general, even in small towns, that this 
 substance is oftener used at the present day. The superior 
 convenience with which it may be obtained makes it pre- 
 ferred to hydrogen, notwithstanding the greater ascensional 
 power of the latter substance. 
 
CHEMISTRY. 
 
 FIG. 12. Carrier pigeon having attached to his tail a quill containing microscopic 
 photographs of dispatches to be sent into Paris during the siege. 
 
 FIG. 13. The tube of quill containing messages as attached to the tail-feathers of 
 a carrier pigeons. 
 
 FIG. 14. Owner's name on the wing of si pigeon. 
 
 Balloons have been used somewhat in recent wars. Thus 
 they were found of considerable service during the siege of 
 Paris, particularly from September 23, 1870, to January 28, 
 
BALLOONS. 
 
 1871. During these last four months of that siege sixty-two 
 
 balloons left the city, and they carried out above two mill- 
 
 ion letters and a great many homing pigeons. Some of 
 
 the birds returned, escaping the 
 
 Prussian sharp - shooters, and 
 
 brought with them letters and dis- 
 
 patches, printed upon the thinnest 
 
 of paper, in the form of micro- 
 
 scopic photographs. The balloons 
 
 also took out of Paris during the 
 
 siege two especially notable passen- 
 
 gers, the one, Leon Gambetta, head 
 
 of the provisional government, who 
 
 left the city for the purpose of con- 
 
 ducting the public business in the 
 
 provinces ; the other, Professor 
 
 Janssen, who had the courage to 
 
 venture out in the darkness of early FIG . 15. Fac-simiie of a micro- 
 
 morning, so as to escape the rifles of ^ n disp L a e ^rf and 
 
 the beleaguring forces. His voy- 
 
 age was for the purpose of reaching 
 
 the station in Algeria from which he 
 
 was to observe the total eclipse of 
 
 the sun, to occur a few weeks later, December 22, 1870. 
 
 Readers who are interested in the use of balloons during 
 
 this memorable siege will find an excellent account in Mr. 
 
 Glaisher's book, Travels in the Air. It contains a descrip- 
 
 tion of the manufacture of air-ships in Paris, together with 
 
 a list of the passengers and an account of the freight of 
 
 those leaving the city when other means of communication 
 
 with the outside world were cut off. 
 
 SSd 
 
 ^ appearance 
 
 The Centenary of Ballooning. 
 
 It is worthy of note that in August, 1883, the centenary 
 of the experiment of the Montgolfier brothers was celebrated 
 by their descendants and others at Annonay by a modern 
 
78 CHEMISTRY. 
 
 balloon ascension and other fetes. These included the dedi- 
 cation of a monument to the two inventors, the monument 
 to be surmounted by a group in bronze representing the two 
 brothers inflating their first balloon. 
 
 READING REFERENCES. 
 Balloons, Their Early History. 
 
 Figuier, L. Les Aerostats ct les Aeronautes. Revue des Deux 
 Mondes. Oct. 1, 1850. p. 193. 
 
 [This interesting article will well repay the reader.] 
 
 Blerzy, H. La Navigation Aerienne. Kevue des Deux Mondes. 
 Nov., 1863. p. 279. 
 
 [Claim is here made, in a general way, that the original invention of the 
 balloon was made at the close of the seventeenth century by a Portuguese named 
 Gusmao.] 
 
 Balloons, Their Recent Uses. 
 
 Glaisher, James, and others. Travels in tlie Air. London. 1871. 
 Hofmann, A. W. Chem. News, xxxii, 231, 241, 255, 265. 
 
 Balloons, Centenary of Their Invention. 
 
 London Graphic. August 25, 1883. 
 
 Balloons, Popular Account of. 
 
 Harper's Magazine, ii, 168, 323; xxxix, 145. 
 Scribner's Monthly, i. 385. 
 Gay-Lussac. 
 
 Arago, D. F. J. (Euvres Completes. Paris. 1854-59. iii, 
 [The Boston Athenaeum library has this work.] 
 
CHLORINE. 79 
 
 XI. 
 
 CHLORINE. 
 
 [HLORINE has extraordinary bleaching powers, 
 and in that form of combination known as 
 bleaching-powder it is extensively used for the 
 whitening of cotton and linen goods. Thus chlo- 
 rine acquires great commercial importance. 
 
 Chlorine is contained in common salt, whether it is in 
 the brine of the ocean or of mineral springs, or whether it 
 occurs as a solid rock. As a constituent of salt, therefore, it 
 becomes an important article of human food. 
 
 Salt is very widely distributed. At Wieliczka, in Austria, 
 mines of solid salt have been worked for hundreds of years. 
 So also at Cardona, in Spain, are what may be called quar- 
 ries of this valuable mineral ; while Cheshire, in England, 
 furnishes immense solid deposits from which salt is obtained 
 to supply the enormous industrial establishments using this 
 substance for the production of chlorine and of compounds 
 of sodium. 
 
 Chlorine was first recognized as a distinct substance by 
 a European chemist, Carl Wilhelm Scheele. He was known 
 to his neighbors as little more than a humble apothecary, 
 even when his chemical experiments were exciting an in- 
 terest all over Europe. Scheele was born at Stralsund, a 
 seaport town of Pomerania, situated on the little strait 
 which leaves the island of Rtigen in the Baltic Sea. He 
 spent the principal portion of his life in Sweden, and on 
 this account is often referred to as a Swedish chemist. 
 Though living in great obscurity and dying at an early age, 
 he yet made many discoveries in chemistry which have 
 rendered his name, otherwise almost unknown, one of the 
 most brilliant in the annals of this science. 
 
 It is related that the King of Sweden, Gustavus III., while 
 
FIG. 16.-Sir Humphry Davy, Bart. Bora In Penzance, England, Dec. 17, 1778 ; died in 
 
 yO years old, occupied, in the opinion of all those who could 
 Judge of such labors, the first rank among the chemists of this or any other age." 
 
 (80) 
 
CHLORINE. 81 
 
 on a journey outside of his own dominions, heard so much 
 of the fame of this chemist, unknown to him before, that he 
 regretted having previously done nothing for him. He 
 therefore commanded that Scheele receive the honor of 
 being created chevalier. "Scheele?" "Scheele?" said the 
 minister charged with this duty. " This is very singular ; 
 what in the world has Scheele done ? " The order was per- 
 emptory, however, and a Scheele was knighted. But, as the 
 reader may perhaps divine, the honor designed for the 
 acute discoverer fell upon another Scheele not upon that 
 Scheele unknown at court but illustrious among the scien- 
 tists of Europe. 
 
 It was this obscure apothecary, then, who added to the 
 list of his other investigations a study of the properties of 
 what was ordinarily considered a dull and uninteresting earthy 
 substance called black magnesia. This study was repaid by 
 the revelation of no less than four hitherto unknown sub- 
 stances: oxygen, barium, manganese, and finally chlorine. 
 Scheele obtained the chlorine in the year 1774 exactly as it 
 is done at the present day ; namely, by bringing together 
 the two substances now called hydrochloric acid and black 
 oxide of manganese, but then known as muriatic acid and 
 black magnesia. 
 
 Scheele believed, and other celebrated chemists concurred 
 in the opinion, that the greenish gas that he discovered was 
 a compound substance. It was not until thirty-six years 
 later that is, 1810, that the distinguished English chemist, 
 Sir Humphry Davy, demonstrated that this gas is not a 
 compound, but is in fact a simple elementary substance; and 
 it was he who gave to it the name chlorine, a name derived 
 from a Greek word (^Awpo^, chloros, meaning light green), 
 conveying an obvious and convenient reminder of one strik- 
 ing property of the thing referred to. 
 
 How Chlorine is Obtained. 
 
 The preparation of chlorine is a very simple matter. It 
 may be accomplished by placing some powdered black oxide 
 
82 CHEMISTRY. 
 
 of manganese, an abundant mineral substance, in any deep 
 glass vessel, and then adding to it four or five times its 
 weight of hydrochloric acid. Any one who performs the 
 experiment will soon perceive the greenish gas rising higher 
 and higher in the vessel, and will soon discover its choking 
 and corosive odor. Moreover, the chlorine gas, which is 
 two and a half times as heavy as air, accumulates within the 
 flask and stays there some time. This is the process which 
 has already been referred to as that which first revealed the 
 gas to Scheele, and this process, with but slight modifica- 
 tion, is that which to-day furnishes the enormous quantities 
 of chlorine demanded by modern industries. 
 
 The Characteristics of Chlorine. 
 
 The three most striking properties of chlorine are its 
 noticeable weight greater than that of the air its greenish 
 color, and its exceedingly irritating odor. Its influence on 
 the animal organism is very violent : more than one exam- 
 ple can be produced of fatal results following the inhalation 
 of too large quantities of the gas. Thus Pelletier, a French 
 chemist, died at Bayonne from the effects of inhaling a con- 
 siderable quantity of chlorine, and Roe, a young Irish 
 chemist of Dublin, lost his life from the same cause, while 
 studying the properties of this gas. 
 
 Chlorine, as a chemical agent, manifests its activities in 
 connection with two principal properties ; namely, its affin- 
 ity for hydrogen and its affinity for the metals. By this 
 statement it is meant that chlorine manifests a strong tend- 
 ency to combine with hydrogen and to combine witli 
 metals whenever these substances arc accessible to it. 
 
 When it combines with hydrogen it , orms the important 
 compound designated by the formula lit.^ and called by 
 the chemist hydrochloric acid, but known in commerce as 
 muriatic acid. 
 
 When chlorine combines with the metals it forms chlo- 
 rides of them. Thus with the metal sodium it forms the 
 compound designated by the formula NaCl and called by 
 
CHLORINE. 83 
 
 the chemist indifferently sodic chloride or chloride of 
 sodium; these will be recognized as the chemical names for 
 the important and well-known substance, common salt. 
 
 Chlorine and Hydrogen Combine. 
 
 Chlorine and hydrogen have a very strong tendency to 
 combine with each other. They manifest this tendency in a 
 variety of ways. Thus, if the two gases are prepared in a 
 dark room, they may be there safely mixed together in a 
 glass vessel; but if the sunlight be allowed to enter and fall 
 upon the vessel there is danger of its being shattered by 
 the explosive violence with which the hydrogen and chlorine 
 immediately unite. As a result of this combination hydro- 
 chloric acid is produced. 
 
 The chemical change is represented by the following equa- 
 tion : 
 
 H 2 -f C1 3 2HC1 
 
 One molecule of One molecule of Two molecules of 
 
 Hydrogen, Chlorine, Hydrochloric acid, 
 
 2 71 73 
 
 parts by weight. parts by weight. parts by weight. 
 
 73 73 
 
 Again, when chlorine is brought in contact with vegetable 
 or animal substances containing hydrogen, it proceeds to 
 withdraw that hydrogen for its own benefit, even though 
 these vegetable and animal compounds are thereby destroyed. 
 
 Although this operation, as well as the foregoing one, pro- 
 duces hydrochloric acid, yet neither method is suitable for a 
 determinate preparation of that substance. It is usually better 
 to prepare hydrochloric acid in another way. Thus it is easily 
 produced by the ac^'jun of sulphuric acid upon common salt. 
 
 Experimental Preparation of Hydrochloric Acid. 
 
 Any one who will take a little trouble may prepare hydro- 
 chloric acid in the way indicated. 
 
 The experiment should be conducted as follows : 
 
 Place a small amount of common salt (Na Cl) in a small 
 
84 
 
 CHEMISTRY. 
 
 retort; to it add enough concentrated sulphuric acid to 
 make a thin paste; connect the neck of the retort with a 
 clean test-tube containing a few drops of water. Now 
 gently heat the retort ; hydrochloric acid will be formed and 
 will distill from the retort and condense in the receiver. 
 
 FIG. 17. Section of furnace used for manufacture of hydrochloric acid. Common 
 salt and sulphuric acid are placed in the large retort A ; upon heating, hydrochloric 
 acid passes into the receivers C, C, C. 
 
 The chemical change is represented by the following equa- 
 tion : 
 
 NaCl + H 2 SO 4 = HC1 -f HNaSCX 
 
 One molecule of One molecule of One molecule of One molecule of 
 
 Sodic chloride, Sulphuric acid, Hydrochloric acid. Hydro-sodic sulphate, 
 
 58 98 36 120 
 
 parts by weight. parts by weight. parts by weight. parts by weight. 
 
 The product of the foregoing experiment may be tested in 
 three ways, and so shown to be in fact hydrochloric acid. 
 
CHLORINE. 85 
 
 First: Take a minute drop on a glass rod and apply it to 
 the tongue and observe the sour or acid taste. 
 
 Second: Take a drop on a glass rod and touch it upon 
 blue litmus-paper. It should turn the paper red. 
 
 Third: Pour a few drops of the liquid into a solution of 
 argentic nitrate (that is, nitrate of silver) in a test tube or 
 other convenient vessel: a white precipitate of argentic 
 chloride will be formed. 
 
 The method of producing hydrochloric acid just described 
 and illustrated is followed in the manufacture of the sub- 
 stance for general chemical purposes. It is also employed 
 for the production of the enormous quantities of it inci- 
 dentally used in the manufacture of bleaching-powder, 
 
 Experiments with Common Salt. 
 
 Chlorine has already been shown to combine with the 
 metal silver, producing the compound designated by the 
 formula Ag Cl, and called argentic chloride and also chloride 
 of silver. This substance may also be prepared very easily 
 somewhat as follows : 
 
 Make a solution of nitrate of silver. Prepare it either by 
 dissolving in water the crystals sold by apothecaries, or by 
 dissolving a small piece of silver in nitric acid. Then make 
 a second clear solution, by dissolving common salt in ordi- 
 nary water. Add the salt solution cautiously, drop by drop 
 to the silver solution. There immediately appear thick 
 masses of white flakes which sooner or later fall to the bot- 
 tom of the vessel. These flakes consist of the argentic chlo- 
 ride (Ag Cl), also called chloride of silver, already referred to. 
 
 The chemical change is represented by the following equa- 
 tion : 
 
 AgNO 3 H- NaCl AgCl + NaNO 3 
 
 One molecule of One molecule of One molecule of One molecule of 
 
 Argentic nitrate, Sodic Chloride, Argentic Chloride, Sodic nitrate. 
 
 169i 58$ 143 85 
 
 parts by weight. parts by weight. parts by weight. parts by weight 
 
 228 228 
 
86 CHEMISTRY. 
 
 This white precipitate produced in this experiment pos- 
 sesses some special interest from its use in photography. In 
 fact chloride of silver, as a thin film upon the surface of the 
 photographic paper, is the principal substance which, by its 
 sensitiveness to light, produces the photographic picture, 
 and any one who tries the experiment last described will 
 soon observe, upon preserving the chloride of silver so pro- 
 duced, that it rapidly grows dark upon exposure to sun- 
 light. 
 
 Bleaching-Powder. 
 
 The substance known as bleaching-powder may be spoken 
 of in a general way as consisting of lime saturated with 
 chlorine. This description points very justly to the method 
 of producing the substance, but gives no idea of the chemi- 
 cal arrangement of the constituents. Scheele early noticed 
 that chlorine gas possesses decided bleaching power, and 
 the French chemist, Berthollet, soon called attention to the 
 possible applications of the substance in the bleaching indus- 
 tries. But its annoying odor made it impracticable to use 
 chlorine on any large scale in the state of gas, and forbade 
 the use of it even when dissolved in water. At length, 
 twenty years after the discovery of the gas that is, in 1798 
 the plan of absorbing chlorine in lime was hit upon, and 
 here may be discovered the beginnings of the bleaching- 
 powder industry, now one branch of the alkali trade, the 
 greatest chemical industry conducted by man. This bleach- 
 ing-powder, at first a mere chemical curiosity, is now manu- 
 factured by the thousands of tons, and is used in the bleach- 
 ing of cotton and linen goods, both in the form of cloth and 
 in the form of the various kinds of paper. 
 
 In another place (pp. 98, 99, 100, 101,) reference is 
 made to the vast proportions attained by the alkali indus- 
 try; meaning the manufacture of certain compounds of 
 sodium, the one produced in largest quantities being doubt- 
 less sodic carbonate (N"a a CO 3 ), commonly called soda-ash. 
 In trade this substance is called an alkali because of certain 
 

CHEMISTRY. 
 
 alkaline properties it possesses, but more strictly speaking it 
 is called a salt sometimes an alkaline salt. In chemistry the 
 single term alkali is reserved for certain compounds called 
 hydrates, of which indeed sodic hydrate having the for- 
 mula NaOH, and often called caustic soda is an appropriate 
 example. This latter compound is at present manufactured 
 on a large scale in connection with soda-ash. 
 
 The alkali trade has passed historically through three 
 well-marked stages. The first stage is the ancient one; 
 in it sodic carbonate is produced from the ashes of sea 
 weeds. The second stage is that of the ascendency of the 
 Leblanc process of making sodic carbonate from common 
 salt. The third stage, the Solvay process, also called the 
 ammonia process, of making sodic carbonate from common 
 salt, has come but recently in vogue, but threatens to absorb 
 the entire field. 
 
 The Leblanc process involves at least three great depart- 
 ments. In the first department sulphuric acid is manufact- 
 ured ; this acid is added to common salt and as a result 
 sodic sulphate and hydrochloric acid are produced; the 
 sodic sulphate is carried to the second department, where it 
 is turned into sodic carbonate that is, soda ash; the hydro- 
 chloric acid is carried to the third department, where it is 
 turned into bleaching-powder. This production of hydro- 
 chloric acid and bleaching-powder contributes somewhat 
 toward the support of the Leblanc process, thus to a certain 
 extent offsetting the decided merits of the Solvay process. 
 
 In the production of bleaching-powder the first step 
 is to mingle hydrochloric acid and manganese dioxide. 
 Chlorine gas is thus generated, much as it is when the 
 experiment is conducted on a small scale as already 
 described. The chlorine so generated is passed into a 
 chamber provided with shelves and containing slaked lime. 
 Hereupon the lime absorbs the chlorine, giving rise to a 
 new substance called bleaching-powder also known as 
 chloride of lime. From what has been said it is evident 
 that chemists know perfectly well what elementary substances 
 
CHLORINE. 
 
 89 
 
 enter into this compound. But there are decided differ- 
 ences of opinion as to the exact way in which the atoms are 
 arranged. Bleaching-powder is generally considered to be 
 a chemical union of calcic hypochlorite and calcic chloride 
 with the addition of calcic hydrate. The following may 
 serve as a formula for the compound: 
 
 CaCl 2 O 2 
 
 (Calcic hypochlorite.) 
 
 CaCl 2 
 
 (Calcic chloride.) 
 
 Ca0 2 H 2 
 
 (Calcic hydrate.) 
 
 FIG. 19 Apparatus for producing bleaching-powder (by passing chlorine gas, 
 generated in A, upon quick-lime spread upon the shelves). 
 
 The use of bleaching-powder offers certain advantages. 
 The following are some of them: 
 The compound is itself white. 
 
 It is a powder which can be easily handled, packed and 
 transported. 
 
 With reasonable precautions the active bleaching agent, 
 chlorine, is retained by the powder in available form for a 
 considerable length* of time. 
 The liberation of this chlorine is easily effected. The 
 
90 
 
 CHEMISTRY. 
 
 addition of almost any acid will accomplish it; even the 
 carbon dioxide of the atmosphere will suffice. 
 
 FIG. 20. Apparatus for "souring" cotton cloth by passing it into dilute acid, before 
 submitting it to the action of bleaching-powder. 
 
 In actual use in the process of bleaching, the entire 
 amount of chlorine originally stored up in the powder may 
 be liberated in contact with the goods to be bleached, 
 
CHLORINE. 91 
 
 In the bleaching of cotton goods chlorine is not the only 
 agent relied upon, though it seems to be an essential one. 
 At least three other substances are employed to contribute 
 to the bleaching. Each of them either removes some colors 
 or stains from the goods or so modifies them that the solu- 
 tion of bleach ing-powder one of the last agents to be 
 employed can the easier finish its work. The three sub- 
 stances referred to are milk of lime, diluted sulphuric acid, 
 and sodic carbonate, also called soda-ash. 
 
 The pieces of cloth, being sewed together in continuous 
 strips many miles in length, pass from one liquor to another, 
 with washings in water at proper times, until finally, after 
 being fully whitened by the chlorine preparation and then 
 receiving the final washing in water, they emerge from the 
 works, completely bleached. 
 
 READING REFERENCES. 
 Alkali Trade, in its Various Branches. 
 
 Clans, C. Chem. News, xxxviii, 263. (Ammonia soda.) 
 Davis, G. B. Chem. News, xxxii, 164, 174, 187, 198, 210, 238. 
 Hargreaves, J. Chem. News, xlii, 322. 
 Kingzett, Charles T. The Alkali Trade. London, 1877. 
 Lunge, G-. Jour, of Chem. Soc. of London, xliv, 524, 528. 
 Mactear, J. Chem. News, xxxv, 4, 14, 17, 23, 35; xxxvii, 16. 
 - Schmidt, T. Chem. News, xxxviii, 203. (Ammonia soda.) 
 
 Weldon, W. Chem. News, xlvii, 67, 79, 87. (Present condition of 
 soda industry.) 
 
 Bleaching-Powder. 
 
 Jurisch, K. Jour of Chem. Soc. of London, xxxi, 350. 
 
 Kingzett, C. T. loc. cit. xxviii, 484. 
 
 Kopfer, F. loc. cit. xxviii 713. 
 
 Lunge, G. Chem. News, xliii, 1. 
 
 Stahlschmidt, C. Jour, of Chem. Soc. of London, xxxi, 279. 
 
 Wolters, "W. loc. cit. xxviii, 404. 
 Chlorine Industry, Future of 
 
 Hurter, F. Jour, of Chem. Soc. of London, xlvi, 225. 
 Chlorine, Preparation of 
 
 Berthelot Annales de Chimie et de Physique. 5 Ser, xxii, 464. 
 
CHEMISTRY. 
 
 Davy, Sir Humphry. 
 
 Davy, John. Collected "Works and Memoirs of Sir H. Davy. London, 
 
 1839. 
 
 Paris, John A. Life of Sir Humphry Davy. London, 1831. 
 Brougham, H. Lives of Men of Letters, etc. London, 1845. p. 448. 
 Cooke, J. P. Scientific Culture. Boston, 1881. p. 11. 
 
 Salt Mines of Europe. 
 
 Harper's Magazine, i, 759. 
 
 Scheele, C. W. 
 
 Hoefer, F. Histoire de la Physique et de la Chimie. Paris, 1872. 
 p. 497. 
 
 Berthollet. 
 
 Davy, John Memoirs of Sir H. Davy. London, 1839. 
 
BROMINE. 93 
 
 XII. 
 
 BROMINE. 
 
 IROMINE is an elementary substance which was 
 first recognized as such in the year 1826. It was 
 detected by Antoine Jerome Balard, a French 
 chemist, who, at the age of twenty-four, was so 
 fortunate and skillful as to discover this interesting substance. 
 He lived at Montpellier, not far from Marseilles, and but a 
 few miles from the Mediterranean. The waters of this great 
 inland sea contain about one tenth more mineral salts than 
 those of the larger oceans, and so it has long been the cus- 
 tom along the southern coasts of France to manufacture salt 
 from them. The water, being drawn from the sea and 
 pumped into successive members of a series of basins or res- 
 ervoirs, evaporates under the warm rays of the southern 
 sun. The basins are about a foot in depth, but aggregate 
 hundreds of acres in area. Little by little the salt separates 
 from the water and is raked out of the basins and transferred 
 to level surfaces called tables. After this principal constit- 
 uent is removed there remains a strong brine called bittern. 
 While experimenting upon this bittern Balard was struck by 
 a peculiar orange-red coloration of great intensity which 
 appeared at certain stnges of his work. Upon further study 
 he was able to demonstrate that this color was due to an 
 elementary substance hitherto unrecognized. Thus he had 
 the felicity of securing for his name permanent renown as 
 one of the few philosophers who have been able to detect a 
 new member of that family of prime and fundamental 
 materials from which is built the structure of the universe. 
 It has already been stated that the elements at present 
 acknowledged are about seventy in number, and some of 
 these were known to the ancients. In some cases a single 
 individual has been able to recognize several new ones; thus 
 
94 CHEMISTRY. 
 
 Scheele has already been mentioned as the discoverer of 
 manganese, barium and chlorine. So it appears that while 
 many eminent men, by conscientious labor, have contributed 
 to the building of the science of chemistry as a noble and 
 harmonious edifice, necessarily but few of them can possibly 
 attain the specially conspicuous honor of having their names 
 forever associated with the first discovery of any of the pri- 
 mary elements. An interesting story is told of the eminent 
 German chemist, Justus von Liebig, in connection with this 
 particular subject. Some years before Balard's discovery 
 there was sent to Liebig, from a German establishment where 
 salt brines were employed, a flask of liquid which was 
 afterward found to contain bromine, or at least to be very 
 rich in bromine with the request that he examine the con- 
 tents. The general appearance of the substance seemed to 
 be that of chloride of iodine, and this circumstance led 
 Liebig to neglect making a more searching investigation. 
 After Balard had published his discovery Liebig perceived 
 his own unfortunate oversight, and occasionally, of course not 
 without some bitter regret, he displayed to his friends this 
 interesting flask, to show them how one might fail to make 
 a discovery of the first importance by reason of some trifling 
 oversight.* 
 
 Distribution of Bromine. 
 
 The name bromine is derived from a Greek word (/3pw^o^, 
 bromos, a bad smell) which suggests the very pungent odor 
 of its vapor. The substance occurs in the brine of the ocean 
 and in that of mineral springs. But of course it does not 
 exist there in the uncombined form; instead, it is united with 
 certain metals in the form of bromides. In sea-water the 
 principal bromide is bromide of magnesium (MgBr 2 ). 
 
 Experimental Preparation of Bromine. 
 
 Bromine may.be prepared by any one who is willing to 
 take a little trouble. 
 
 *Schutzenber,ger, Paul; Traitede Chimie Generate, Parts, 1930. i, 375, 
 
BROMINE. 95 
 
 Place in any suitable glass vessel a small amount of 
 manganese dioxide, some potassic bromide (commonly known 
 as bromide of potassium), then some water, and finally a 
 small quantity of hydrochloric acid. Bromine is almost 
 instantly liberated, and shows its presence by imparting to 
 the liquid an orange hue. If the vessel is covered lightly, 
 and then gentle heat is applied to it, the bromine will be 
 expelled from the liquid and will appear above it as a heavy 
 vapor of a rich reddish-brown color. Some care 'must be 
 exercised, however, in conducting this experiment, since the 
 vapor is very irritating to the eyes and also to the throat, 
 and it has a general corrosive effect upon most substances 
 with which it comes in contact. 
 
 Chemical Properties of Bromine. 
 
 In its chemical relations bromine shows very decided 
 resemblances to chlorine, having affinities for the same sub- 
 stances, only less in intensity. Since its discovery it has found 
 a considerable number of uses. Thus, it is an important sub- 
 stance in the processes of photography; and the enormous 
 expansion and growth of this art within a very few years 
 has required in the aggregate large quantities of bromine. 
 The considerable demand for bromine, which at first increased 
 its price, has produced, as might have been anticipated, a 
 stimulating influence upon the manufacture of it. This has 
 led to greatly increased production of the substance, not only 
 in Europe but also in the United States. In Pennsylvania, 
 Ohio and West Virginia it has become an important article 
 of manufacture; in fact, the United States now furnishes 
 the largest proportion of the entire amount of the material 
 produced in the world. 
 
 One of the most important compounds of bromine is that 
 produced by its union with silver. We refer to argentic 
 bromide (commonly called bromide of silver, AgBr). This 
 substance may be easily produced by the following simple 
 experiment. 
 
96 
 
 CHEMISTRY. 
 
 To a solution of potassic bromide in water add a water 
 solution of argentic nitrate; a white or yellowish-white pre- 
 cipitate immediately appears. 
 
 FIG. 21. Louis Jacques Mand Dagruerre, from whom the daguerreotype was 
 named. Born at Cormeilles, France, 1789; died, 1851. 
 
 The chemical change is represented by the following 
 equation: 
 
 KBr -f- AgNO 3 = AgBr -f KNO 3 
 
 One molecule of One molecule of One molecule of One molecule of 
 
 Potassic bromide, Argentic nitrate, Argentic bromide, Potassic nitrate, 
 
 119 169 187 101 
 
 parts by weight. parts by weight. parts by weight. parts by weight. 
 
 288k 
 
 The argentic bromide produced, at first nearly white in 
 color, has the power of becoming black upon exposure to 
 
PLATE IV. Photographer at work in a room lighted through a window of red 
 glass. (Red glass cuts off the chief actinic, or chemical, rays of sunlight.) 
 
BROMINE. 97 
 
 light, and it is this important property which makes the sub- 
 stance suitable for use in the process of photography. 
 
 Again, in the form of potassic bromide, bromine has had 
 a very wide and beneficent use as a remedial agent; it is 
 largely used in the manufacture of the salt last mentioned. 
 
 READING REFERENCE. 
 Liebig, His Life-Work in Chemistry. 
 
 Hofmann, A. W. Jour, of Chem. Soc. of London, xxviii, 1065. 
 
 7 
 
98 CHEMISTRY. 
 
 XIII. 
 
 IODINE,, 
 
 ODINE belongs to what may be called a chemical 
 family, the other members being chlorine and 
 bromine. All three of these elements are found 
 in sea-water, but in very different quantities. 
 Thus chlorine is extremely abundant ; bromine is in the water 
 in minute quantities, while iodine exists there in amounts 
 that are exceedingly small. They all exist as salts, of which 
 of course chloride of sodium is by far the most abundant. 
 It has already been shown that bromine is obtained from sea- 
 water, after enormous amounts of the water have been con- 
 centrated by evaporation. But iodine, the third element of 
 the group, exists in sea-water in quantities so very minute 
 that it cannot be directly extracted from it at any practicable 
 cost. Even the concentration method just alluded to is not 
 applicable in the case of iodine. It happens, however, that 
 sea-weeds have the power of extracting from sea-water even 
 the exceedingly minute amount of iodine, or of iodides, that 
 the water contains ; and, moreover, when sea-weeds are 
 burned, iodides are fo:md in their ashes. 
 
 The Discovery of Iodine. 
 
 The discovery of iodine is associated with the history of 
 certain of the most important and interesting products of the 
 chemical arts. It also has a striking connection with some of 
 the political and military affairs of France, and, indeed, of 
 Europe, in the early years of the present century. Finally, 
 its great usefulness to mankind is in marked contrast with 
 the misfortunes that overtook its discoverer. 
 
 The discovery of iodine is directly referable to the old 
 soda industry. The term, soda is a general one, and it was 
 
IODINE. 
 
 99 
 
 formerly used to include several different chemical compounds 
 manufactured from the ashes of sea-weed. Decidedly the 
 most important of these is sodic carbonate. This substance 
 has a well marked alkaline reaction, and although not an 
 alkali in the strictest chemical sense, it is yet the principal 
 product of that greatest of all the chemical industries, known 
 as the alkali trade. (See pp. 86 and 88.) During the last sixty 
 years and after many early trials and failures, the production 
 
 FIG. 22. Catherine the harvest of sea-weed for the manufacture of soda-ash. 
 
 of the various alkaline compounds of sodium has risen to 
 enormous proportions, such that in England, alone the annual 
 product of sodic carbonate, the principal one, is probably more 
 than six hundred thousand tons. This vast amount of alkali 
 is consumed by civilized peoples in some of their most exten- 
 sive industries, such as the manufacture of soap and of gla^s, 
 and in many processes of bleaching. The extension of these 
 branches of business has, of course, gone hand in hand with 
 the increased production of alkali. Indeed, on the one side 
 there has been a steady diminution in price and on the other 
 a steady increase in consumption ; probably each circum- 
 
100 
 
 CHEMISTRY. 
 
 stance may be considered as both cause and effect of the 
 other. Prior to 1793, however, the demands for alkali 
 vastly smaller than to-day were all satisfied by the material 
 obtained from the ashes of marine plants. Thus along the 
 coasts of Great Britain, France, and especially of Spain, sea- 
 weed of various kinds was gathered as a very important 
 harvest. Some of the weed was used as a fertilizer of the 
 soil ; more was dried and burned for the sake of the ashes. 
 
 FIG. 23. Varieties of sea-weed used to produce varech. 
 
 On the British coast the ash was known as kelp ; that pro- 
 duced on the coasts of Normandy was called varech, and 
 that produced on the Spanish coast went by the name of 
 barilla. 
 
 Now one of the important indirect effects of the French 
 Revolution was that felt by the consumers of the old-fash- 
 ioned alkali. In 1793 an embargo was put upon the supply 
 of alkaline ashes, such as kelp and barilla, into France. But 
 the French demand for alkali from sea-weed that is, sodic 
 alkali, was very much stimulated by the draft upon the potas- 
 
IODINE. 101 
 
 sic alkali for the preparation of the great amounts of salt- 
 petre required for the manufacture of gunpowder. The 
 immediate effect, therefore, was favorable to the sudden 
 development of an invention by a French physician, Leblanc, 
 by which alkaline compounds of sodium could be manufact- 
 ured independently of the ashes of sea-weed that is, from 
 common salt. Notwithstanding the stimulus of the political 
 affairs referred to, and the fostering help of the Government, 
 the complexity of the Leblanc process was such that it was 
 slow in gaining a foothold as a practical industrial method. 
 But after its first successful establishment as a regular bus- 
 iness, and up to almost the present day, the application of 
 this process has continually widened, and for a long time 
 the method held undivided sway in its important field. 
 
 In the year 1811 Bernard Courtois, a French chemist, was 
 engaged, just as other manufacturers were, in the production 
 of nitrate of potash, or saltpetre, for use in gunpowder. He 
 also manufactured soda from varech. In order to separate 
 the alkali from the varech in a more refined condition the 
 raw varech was subjected to a very careful purification. At 
 certain stages of his experiments Courtois was struck with 
 the corrosion of his copper kettles ; he also observed that this 
 corrosion was most violent with certain liquids which, upon 
 the addition of sulphuric acid, gave rise to the production of 
 a magnificent violet vapor. He did not make the matter 
 public, however, until late in the year 1813, when Ampere 
 brought the substance to the attention of Sir Humphry Davy, 
 the distinguished English chemist, who was then visiting 
 Paris. Davy at once recognized it as a new element of sim- 
 ilar character to chlorine. The next year, 1814, the substance 
 was carefully investigated by Gay-Lussac, who gave to the 
 world a very full description of its properties, -and who called 
 it iodine, from a Greek word (loeid^g, ioeides, violet colored), 
 suggesting the striking and characteristic color of its vapor. 
 The political events of 1815 ruined the business of Courtois, 
 and he sunk into poverty from which he was not able to re- 
 cover, until finally he died, in 1838, poor and almost forgotten. 
 
102 
 
 CHEMISTRY. 
 
 Present Sources of Iodine. 
 
 Although kelp, varech and barilla are no longer used for 
 the direct purpose of aifording alkali, they are still produced 
 with a view to their yielding iodine. On the rough and 
 stormy coasts of Scotland, Ireland, France and Spain, large 
 quantities of sea-weeds are cast ashore. They are collected, 
 they are dried in the sun, they are then burned, and their 
 ashes are employed, but principally in the manufacture of 
 iodine. Thus on the coasts of Brittany and Normandy the 
 occupation of collecting weeds occupies three or four thou- 
 sand families for the larger part of the year. 
 
 Experimental Method of Preparing Iodine. 
 
 Iodine may be prepared in a manner closely resembling 
 the process already described for bromine that is, by placing 
 in a suitable glass vessel a small amount of manganese diox- 
 ide, some potassic iodide (commonly known as iodide of 
 
 potassium), then 
 some water, and 
 finally a small 
 quantity of hy- 
 drochloric acid. 
 Iodine is almost 
 instantly liber- 
 ated, and shows 
 its presence by 
 imparting to the 
 liquid a brown- 
 ish color. If the 
 vessel is cov- 
 ered lightly and 
 then gentle heat 
 FIG. ~4. -Changing iodine to a violet vapor by means of heat. 1S applied to it 
 
 the iodine will 
 
 be expelled and appear in the vessel above the liquid as a 
 heavy vapor of a rich violet color. This vapor readily con- 
 
IODINE. 
 
 103 
 
 denses on the upper and colder portions of the vessel in the 
 form of minute crystals of a color almost black. This is 
 almost precisely the method employed on the large scale for 
 the production of iodine from kelp. 
 
 Chemical Properties of Iodine. 
 
 The chemical characteristics of iodine are throughout 
 closely allied to those of chlorine and of bromine, only, in 
 general, iodine may be said to have weaker chemical affinities 
 than either of the other two. 
 
 FIG. 25. Apparatus used in the manufacturing process for obtaining iodine. The 
 retorts C, C, are surrounded by sand (sand-bath); the heat drives iodine, in form of 
 vapor, Into the receivers, A, A, where it solidifles. 
 
 Iodine produces compounds of the same general type as 
 the others, and of this an example is found in argentic iodide. 
 The following method of producing it can be followed by 
 almost any one. Prepare a solution of nitrate of silver in 
 water, and then add a water solution of potassic iodide ; a 
 chemical change takes place, with the production of a yellow- 
 ish-white precipitate. This precipitate is argentic iodide. 
 Upon exposure to sunlight it readily changes in color, becom- 
 ing almost black. This is an important characteristic and is 
 made use of, as is the same property possessed by argentic 
 
104 OHEMISTHT. 
 
 bromide and also by argentic chloride, in the production of 
 the photograph. And while it is a fact, and one well known, 
 that many of the salts of silver blacken more or less upon 
 exposure to sunlight, it is found that the chloride, the bro- 
 mide and the iodide have properties particularly fitting them 
 for the purposes of photography. In discussing bromine, 
 reference was made to the influence of the great expansion 
 of the photographic business ; and this circumstance has 
 stimulated the demand for iodine just as for bromine. It 
 was also pointed out that potassic bromide is an important 
 remedial agent ; potassic iodide is likewise of great medicinal 
 value. 
 
 Starch as a Test for Iodine. 
 
 Iodine, when in the free or uncombined condition, has a 
 remarkable and very peculiar way of attaching itself to gran- 
 ules of starch. 
 
 This property may be demonstrated by a simple and attract- 
 ive experiment. Thus, if starch is boiled with water and then 
 the hot mass is poured into cold water, minute particles of 
 starch distribute themselves through the liquid. If to this 
 liquid a very small amount of free iodine is added, the starch 
 instantly takes on a deep blue color. If to another portion 
 of the same or similar starch suspended in water, iodine is 
 added in a combined form that is, as potassic iodide, for 
 example absolutely no change of color is detected. These 
 two experiments show that the iodine only attacks starch 
 when the iodine is free and uncombined. 
 
 READING REFERENCES. 
 Gay-Lussac. 
 
 Davy, John. Memoirs of Sir H. Davy. 
 Chlorine, Bromine, Iodine, and Fluorine. 
 
 Mylius, E. Cliem. News, xxxiii, 244, 253; xxxiv, 5, 13. 25, 33, 45, 
 
 55, 66, 78, 86, 118, 139, 149, 166, 180, 188, 197, 215, 233. 
 Iodine, Manufacture of 
 
 Schmidt, T. Chem. News, xxxvii, 56. 
 
 Stanford, E. C. G.Loc. tit. xxxv, 172. 
 Iodine, Discovery of 
 
 Davy, John. Memoirs of Sir H. Davy. pp. 164-180. 
 
 Paris, John A.-- Life of Sir H. Davy. pp. 267-278. 
 
FLUORINE. 105 
 
 XIV. 
 
 FLUORINE. 
 
 are a number of compounds known whose 
 various properties, powers of chemical interchange 
 and special molecular weights, clearly point out 
 the existence in them all of a certain peculiar 
 element analogous in many respects to chlorine, bromine and 
 iodine. To this element the name fluorine has been given. 
 
 Its properties in these combined forms have been Carefully 
 studied and well made out. Thus, like chlorine and its family 
 associates, it combines with hydrogen to form an acid, 
 hydrofluoric acid (HF), properly comparable with the acids 
 formed by the three elements last discussed- 
 
 Hydrofluoric acid, HF. 
 
 Hydrochloric acid, HC1. 
 
 Hydrobromic acid, HBr. 
 
 Hydriodic acid, H I. 
 
 It also combines with the metals to form fluorides. The 
 best example of these fluorides is that compound in which 
 fluorine most commonly occurs in nature that is, fluor-spar, 
 the mineral substance whose chemical name is calcic fluoride, 
 and whose composition is expressed by the formula CaF 8 . 
 
 Many experiments have been performed for the purpose of 
 isolating the element itself. While none of these have as 
 yet been accepted as entirely satisfactory, some recent ones, 
 especially, have been so far successful as to indicate the 
 probability that fluorine is a colorless gas. It seems reason- 
 able to suppose that if fluorine were a solid or liquid at 
 ordinary temperatures some processes that have been devised 
 would be capable of producing and detaining at least a small 
 quantity of the elementary substance, and that from this the 
 observer would be enabled to recognize and discover at least 
 some of the properties of the fluorine itself. 
 
106 CHEMISTRY. 
 
 Properties of Fluorine. 
 
 The property above all others that is characteristic of 
 fluorine is its striking affinity for silicon. With this element 
 it readily combines under a variety of circumstances. More 
 wonderful still, the compound produced with it is a gas. 
 Now in general the compounds of silicon are solids. These 
 solids are many of them familiarly known in those material.* 
 which constitute the principal portions of the stable earth on 
 which we tread, of the rock beneath it and of the enduring 
 mountain masses that here and there pierce through the soil 
 and raise their crests above the general level. The majority 
 of these earthy and rocky substances are silicates. It is ap- 
 parent, then, that the compounds of silicon are types of 
 solidity and stability. They cannot be melted except in the 
 most powerful heating appliances, and the idea of their being 
 vaporized by heat alone is quite inconsistent with the 
 ordinary properties recognized in them. 
 
 So then it seems strange and almost contradictory that 
 fluorine should have the power of attacking compounds that 
 seem to be the embodiments of permanency itself yet it 
 readily does so. Thus, if hydrofluoric acid comes in contact 
 with silicon, whether that substance is in combination as sand 
 or as hard rocky minerals, the fluorine atoms pluck out the 
 silicon and then they fly away together in the form of gas or 
 vapor. Again, hydrofluoric acid may be spoken of as the 
 unique agent that readily attacks glass, and dissolves, and 
 even destroys, this ordinarily unchangeable substance. 
 
 Finally, there may be added what can be said of no other 
 dement; namely, that fluorine is not known to form any com- 
 pound with oxygen. 
 
 Discovery of Hydrofluoric Acid. 
 
 It is not easy to refer the first knowledge of fluorine to 
 any particular discoverer. Perhaps, however, renewed men- 
 tion of the ingenious Scheele is not out of place here ; for it 
 
FLUORINE. 
 
 107 
 
 seems to have been he who for the first time, and as early as 
 1771, recognized hydrofluoric acid as a special acid. He 
 called it fluoric acid, but he 
 did not obtain a correct idea 
 of its composition. Scheele 
 prepared the acid from a well- 
 known mineral, fluor-spar, and 
 by the addition of sulphuric 
 acid. This operation cannot 
 be performed to advantage in 
 a glass or porcelain vessel, for 
 they contain silicon, and, as has 
 been suggested already, sili- 
 cious matters are freely attacked by the acid produced. The 
 decomposition, therefore, is commonly conducted in a retort 
 of lead, or in one of platinum, and the acid produced is col- 
 lected in a receiver also constructed of one of these metals. 
 
 The chemical change is represented by the following 
 equation : 
 
 FIG. 26. Platinum retort and receiver 
 shown with its several parts separated. 
 
 CaF 2 -f 
 
 H 2 SO 4 
 
 2HF 
 
 f CaSO 4 
 
 One molecule of 
 
 One molecule of 
 
 Two molecules of 
 
 One molecule of 
 
 Calcic fluoride, 
 
 Sulphuric acid, 
 
 Hydrofluoric acid, 
 
 Calcic sulphate, 
 
 78 
 
 98 
 
 40 
 
 136 
 
 parts by weight 
 
 parts by weight. 
 
 parts by weight. 
 
 parts by weight. 
 
 176 
 
 176 
 
 Ordinarily the product is a liquid, and consists of water 
 holding in solution the acid (HF). It is possible, however, 
 to prepare the acid free from water and still in a liquid 
 form. 
 
 But in this condition it is one of the most dangerous, pois- 
 onous and corrosive substances known. It produces painful 
 burns if it falls upon the flesh, and fatal results have been 
 known to follow injuries received from it. Thus, in 1869 
 Professor Nickles, an eminent French chemist, died from 
 injuries sustained by the accidental inhalation of hydrofluoric 
 acid vapor while studying the properties of the substance. 
 
108 
 
 CHEMISTRY. 
 
 Etching Glass by Hydrofluoric Acid. 
 
 The effect of hydrofluoric acid upon glass may be shown 
 in attractive form, and without much difficulty or danger, by 
 the help of a small dish of lead and a plate of glass to cover 
 it. These being provided the experiment may be conducted 
 somewhat as follows: Melt a little beeswax upon the glass so 
 that the wax may form a thin film upon one side of it. Then 
 allow the wax to cool and harden. Next, by use of any con- 
 venient pointed instrument, draw some sketch or design deep 
 in the wax in fact, to the surface of the glass. Next place 
 some powdered fluor-spar in the leaden dish, and add to it 
 
 some concentrated 
 sulphuric acid. Now 
 cover the dish, with 
 the glass already 
 prepared, in such a 
 way that the sketch 
 or design is turned 
 downward so as to 
 receive the fumes of 
 hydrofluoric acid as 
 they rise from the 
 
 FIG. 27. Platinum retort and receiver shown as ar- mixture in the dish 
 ranged for production of hydrofluoric acid (HF). 
 
 It is easily under- 
 stood from what has been said already that the hydrofluoric 
 acid will attack the glass, carrying away some of its silicon 
 in the form of gas or vapor. As a result of this action, minute 
 channels are formed in the glass. When the experiment is 
 thought to be sufficiently advanced the wax may be removed 
 from the plate by melting it off or otherwise ; thereupon it 
 will be discovered that the glass has actually become etched 
 or engraved by the hydrofluoric acid gas. 
 
 In 1788 Puymaurin presented to the French Academy of 
 Sciences such a glass plate, upon which there was a beautiful 
 fluoric etching representing Chemistry and Genius weeping 
 at the tomb of Scheele, who had contributed so much to the 
 
FLUORINE. 109 
 
 history of hydrofluoric acid. "This work," says Hatty, "was 
 of interest to the Academy on account of the fitness of the 
 subject as well as the elegance of its execution." 
 
 Practical Application of Hydrofluoric Acid. 
 
 Hydrofluoric acid, formerly a mere chemical curiosity, has 
 now become a familiar article upon the shelves of the drug- 
 gists. It is sold in gutta-percha bottles with rubber stoppers. 
 It is often used by jewelers to correct errors in the applica- 
 tion of silicious enamels upon their work. Thus, if the 
 enamel has been incorrectly placed, it may be removed by 
 hydrofluoric acid and afterward a new portion may be intro- 
 duced in the proper position. Again, it is largely used in the 
 decoration of artistic glass objects, such as globes for gas 
 
 FIG. 28. Leaden tray and glass plate. The tray is Intended to receive the materials 
 for production of hydrofluoric acid ; the plate is represented as covered with a var- 
 nish, through which a sketch has been drawn, preparatory to etching. 
 
 chandeliers, and the multitude of articles of table glass-ware. 
 In engraving such objects they are first covered with a 
 suitable varnish that will resist the hydrofluoric acid, then the 
 design is drawn through the varnish with a sharp needle; 
 afterward the article is exposed to the gas and etched in a 
 manner similar to that already described. 
 
 READING REFERENCES. 
 Hydrofluoric Acid. 
 
 Gore, G. Jour, of Chem. Soc. of London, xxii, 368. 
 Fluorides. 
 
 Fremy, E. Annales de Chimie et de Physique. 3 Ser. xlvii, 5. 
 Fluorine, Isolation of. 
 
 Moissan, H. Chem. News, liv, 36, 51, 80. 
 
110 CHEMISTRY. 
 
 XV. 
 
 OXYGEN. 
 
 |XYGEN may justly claim a high degree of impor- 
 tance as a subject for the study alike of the pro- 
 fessional chemist and the casual reader. This 
 importance depends upon a variety of considera- 
 tions. Among them are the surpassing abundance of the 
 substance itself, the great number of compounds into which 
 it enters, the activity of its chemical powers, and finally, the 
 interesting circumstances under which its distinct recognition, 
 or, as perhaps we may say, its discovery, was attained. 
 
 Its great abundance has been pointed out already in the 
 declaration that oxygen makes up, by weight, fully one half 
 of our terrestrial globe including earth, ocean and air. The 
 air is about one fifth oxygen by weight ; all water, wherever 
 existing, is sixteen-eighteenths oxygen by weight, while 
 quartz, sand, and other similar wide-spread and most com- 
 monly occurring mineral matters are a little more than one 
 half oxygen. Other solid matters than the rocks, such as 
 most parts of the material structures of animal and vegetable 
 beings, contain oxygen as an important constituent element. 
 While thus we have scanned the great multitude of sub- 
 stances spread immediately about us by the hand of nature, 
 and found oxygen in them all, it is none the less true that 
 oxygen is an important factor in artificial products that is, 
 those resulting from man's manufacturing operations. 
 
 Chemical Activity of Oxygen. 
 
 Again, oxygen plays a part of exceeding activity in some 
 of the grandest chemical processes of nature and of the arts. 
 
 For example, it is essential to the vital processes of all 
 animals. Wherever a living being inhales the breath of life, 
 whether from the fresh air of the mountain tops, or from the 
 
OXYGEN. HI 
 
 populous streets of the swarming metropolis, or from, the sol- 
 itary deck of the bark that creeps with the ocean's currents, 
 or wherever the humbler servants of man's table find their 
 way through unexplored depths of the ocean and pluck from 
 its waves the modicum of life-giving gas dissolved within them, 
 there is this wonderful agent, which has no substitute, sus- 
 taining by active processes, truly chemical, that vitality of 
 man or of beast which gives to nature its forms of highest 
 beauty and most admirable intelligence. 
 
 Again, oxygen is the necessary agent in all ordinary com- 
 bustions. So wherever a fagot, glowing beneficently in a 
 sparsely peopled forest, helps to sustain man's vital spark ; or 
 where, in a highly civilized community, the fires on the altars 
 of modern industry draw from the flinty rocks the metals that 
 serve to give employment to millions of children of toil ; 
 there oxygen is ever active, the true supporter of the com- 
 bustion of all those flames which in the past have served as 
 signs of life and civilized activity, and which are still the 
 best symbols of vitality and intelligence. 
 
 The Discovery of Oxygen. 
 
 The first discovery of oxygen is usually attributed to Dr. 
 Joseph Priestley, an English clergyman and student of nat- 
 ural science. He lived in a time when men's minds all over 
 Europe were strongly drawn toward the pursuit of chemical 
 knowledge. In fact, at almost the same moment that Priestley 
 was enthusiastically conducting his experiments Scheele was 
 also producing oxygen in his apothecary's chamber in Sweden. 
 And the brilliant Lavoisier, prominent among the men of 
 distinction who thronged the gay capital of France, was also 
 working in the same direction ; it was he who said about 
 oxygen, in one of his own chemical works : " Cet air que nous 
 avons decouvert presque en meme temps, Dr. Priestley, M. 
 Scheele et moi," so that he is sometimes declared by his 
 enthusiastic countrymen to be entitled to the merit of the 
 earliest discovery of this most magnificent of elements. 
 
FIG. 29. Joseph Priestley. 
 
 Born near Leeds, England, March 13, 1T33 : died in Northum- 
 berland, Pa., February 6, 1804, 
 (112) 
 
OXYGEN. 113 
 
 Priestley's life included ample materials for a romance. On 
 -the one hand, the ingenious discoverer in physics and chem- 
 istry, and the friend of that Benjamin Franklin who was 
 then minister at the brilliant court of France from a handful 
 of colonies that appeared capable of being plucked up by the 
 roots, but were instead destined to grow to an unrivalled em- 
 pire himself a figure in a romance ; and, on the other side, 
 a preacher to a dissenting congregation ; a victim of public 
 odium for his liberal opinions on religious and political sub- 
 jects ; his house set on fire by a mob, his apparatus wrecked, 
 his library cast to the winds ; finally, an emigrant with his 
 wife and children to a village in Pennsylvania, then almost un- 
 known, whose little burial-ground still gives his bones repose ; 
 these are but brief suggestions of the trials of this perturbed 
 spirit, in his life "sadly driven about and tossed," now 
 cherished as one of those who in the realm of thought has 
 made no mean contribution to the glory of the English 
 name. 
 
 Dr. Priestley prepared oxygen from red precipitate of mer- 
 cury, a substance now designated by the name mercuric oxide 
 and by the formula HgO. Heating this substance in a 
 receiver, and by means of a burning-glass or lens, he observed 
 that a peculiar kind of air was evolved. He further discov- 
 ered that this air had an unusually stimulating influence upon 
 burning bodies, and was well suited for the respiration of 
 living animals. Priestley's prime experiment was performed 
 on the 1st day of August, 1774; a date which may be accepted 
 as almost the birthday of modern chemistry. 
 
 Like many other great discoverers, Priestley was, to a cer- 
 tain degree, anticipated. Thus a certain John Mayow, an 
 English physician, fully a hundred years before the time of 
 Priestley's experiment, enunciated the doctrine that the at- 
 mosphere contains an air in a certain sense the essential food 
 of animal life and of flame. But these wonderful views ot 
 Mayow, brought forward too early for the state of thought 
 at his time, lay dormant and unproductive for an entire 
 century. 
 
 8 
 
114 CHEMISTRY. 
 
 First Method of Preparing Oxygen. 
 
 Oxygen may be prepared in many ways, but only two need 
 receive attention here. The first method is Priestley's. If 
 the red oxide of mercury is heated over a powerful gas flame 
 and in a tube of not easily fusible glass, the oxygen passes 
 from the metal, and may be carried by any small conducting 
 tube into a convenient receiver filled with water and standing 
 in the pneumatic trough. If the gas so collected is tested by 
 means of a candle having only a spark on its wick, the oxy- 
 gen is readily recognized by the fact that the taper promptly 
 bursts into a full and brilliant flame. This method is of his- 
 torical interest chiefly, though it may well attract some atten- 
 tion from the simplicity of the chemical change involved. 
 Thus this change is represented by the following equation : 
 
 2HgO healed O 2 + 2Hg 
 
 Two molecules of One molecule of Two atoms of 
 
 Mercuric oxide, Oxygen, Mercury, 
 
 432 32 400 
 
 parts by weight. parts by weight. parts by weight. 
 
 432 . 432 
 
 A word about the pneumatic trough is not out of place 
 here, because this useful contrivance was the invention of 
 Priestley. The name may be appropriately applied to almost 
 any vessel of water in which may stand the open mouth of a 
 bell-glass suitable for containing gas. The water serves at 
 once to seal the mouth of the jar, and also to afford a mate- 
 rial through which the exit tube of an appliance may be 
 dipped, and through which also the gas from the tube may 
 freely and conveniently flow into the bell-glass. Before 
 Priestley's time gases had been collected in bladders or 
 varnished bags, but the new contrivance furnished a much 
 superior means of detecting small quantites of gas and 
 working with them. 
 
 Again, for all the ordinary purposes of experimenting with 
 gases, no appliance superior to that of Priestley has yet been 
 devised. 
 
OXYGEN. 115 
 
 Second Method of Preparing Oxygen. 
 
 The second method, and that oftenest pursued, employs a 
 salt not known in Priestley's time. This salt is called potassic 
 chlorate, and is represented by the formula KC1O 3 . 
 
 This substance, when heated, evolves a large amount of 
 oxygen, but it does so with almost explosive violence. 
 
 The chemical change is represented by the following equa- 
 
 2KC\O 3 heated 2KC1 + 3O 2 
 
 Two molecules of Two molecules of Three molecules of 
 
 Potassic chlorate, Potassic chloride, Oxygen, 
 
 245 149 96 
 
 parts by weight. parts by weight. parts by weight. 
 
 245 245 
 
 On the other hand, if the potassic chlorate is mixed with 
 about one third of its weight of the earthy mineral known 
 as black oxide of manganese (but called by the chemist, 
 manganese dioxide), the mixture when heated evolves oxygen 
 more slowly and continuously than the chlorate alone and it 
 does it at a lower temperature. Strangely enough, however, 
 the manganese dioxide appears to take either no chemical 
 part in the operation, or else only a very obscure one. Indeed, 
 some other oxides will serve the same purpose, while they 
 likewise appear to undergo no easily-detected chemical change. 
 
 In this method, as in the other, the oxygen gas produced 
 may be collected in a bell-glass over the pneumatic trough, 
 and afterward its nature may be demonstrated as before by 
 means of the taper having a spark upon it. 
 
 The Properties of Oxygen. 
 
 It has been the custom of chemists to say of oxygen that 
 it is a permanent <jas. The force of this expression is found 
 in the fact that until recently all attempts to liquefy it were 
 futile. But recent experiments, with apparatus capable of 
 subjecting it at once to more intense cold and to greater 
 pressure than were ever before employed, seem to demon- 
 
116 CHEMISTRY. 
 
 strate that it will turn to a liquid when these conditions are 
 carried to a sufficient extreme. 
 
 That oxygen is colorless and odorless appears plain from 
 the properties of the atmospheric air throughout which this 
 gas is thoroughly diffused and intimately intermingled, 
 although it constitutes but one fifth of it. 
 
 FIG. 30. The rays of sunlight concentrated, by a lens, upon a diamond placed in 
 oxygen gas, with a view of proving the combustibility of the gem. 
 
 Chemical Properties of Oxygen. 
 
 Of the chemical powers of oxygen the most striking and im- 
 portant seems to be its marked tendency to combine with other 
 elementary substances. In many cases this combination does 
 not commence except when the substances are heated. Thus 
 the noble buildings of a city are every day and every night 
 
OXYGEN. 
 
 117 
 
 continuously and harmlessly bathed within and without by 
 that same oxygen that, in time of conflagration, is ready 
 chemically to combine with their elements, and as a result to 
 reduce the metropolis to ashes. But such combination, once 
 inaugurated, often itself affords sufficient heat not only to 
 make the process continue, but also to generate that flame or 
 fire which is the token of what is ordinarily called combustion. 
 
 FIG. 31. The burning of a spiral of iron wire in a jar of oxygen gas. 
 
 In this view, oxygen is often spoken of as a supporter of 
 combustion. That this property, known to be associated 
 with the atmospheric air, does in fact reside in the oxygen 
 of it, is to some extent proved by the more rapid and brilliant 
 combustion of the candle in pure oxygen. 
 
 Another interesting experiment is performed when a piece 
 of charcoal, which may be supported on a wire, is burned a 
 little so as to acquire a spark and then is dipped in oxygen 
 gas. The single coal would soon cease to burn in atmos- 
 
118 CHEMISTRY. 
 
 pheric air, but it burns readily and brilliantly in pure 
 oxygen. 
 
 Even the diamond, the most compact and imperishable 
 form of carbon known, may burn in pure oxygen gas just as 
 the most humble piece of coal does, and the relationship of 
 the gem to the commonplace fuel is proved by this exper- 
 iment. 
 
 Still another experiment in the same direction may be con- 
 ducted with sulphur. For this purpose a fragment of sulphur 
 set on fire may be dipped in a jar of pure oxygen. The sul- 
 phur burns with vastly increased rapidity, and with a violet 
 tiame much more brilliant than that of sulphur burning in air. 
 
 Again, some substances not ordinarily considered combus- 
 tible will burn in oxygen gas. Thus a bundle of iron wire, 
 to which a little lighted chip is attached, itself takes fire and 
 burns brilliantly when dipped into oxygen gas. 
 
 The Products of Combustions in Oxygen. 
 
 As a necessary result of the combustion of substances in 
 oxygen there are produced a multitude of compounds called 
 oxides. 
 
 This is true of the candle, which consists mainly of carbon 
 and hydrogen. When the candle burns these two substances 
 change into oxides. The carbon produces carbon dioxide, 
 whose formula is CO 2 , and which is familiarly known as car- 
 bonic acid gas. This oxide, it is true, is not easily recognized 
 by the ordinary observer, because it is an invisible gas; but the 
 chemist can prove that it is in fact the product of this com- 
 bustion. At the same time the hydrogen produces an oxide 
 whose formula is H 2 O, which will be recognized as the chem- 
 ical expression for water. And so water is in fact produced, 
 though in the form of vapor, by the burning candle. 
 
 Charcoal is composed almost entirely of what the chemist 
 calls carbon, and when it burns it produces the oxide called 
 carbon dioxide (CO 2 ). This is the same invisible gas that 
 has already been declared to be produced when the carbon 
 
OXYGEtf. 113 
 
 of the candle is burned, and in this case, as in the other, it is 
 easy for the chemist to prove its presence. 
 
 In the case of carbon, the chemical change is represented 
 by the following equation : 
 
 C + O a CO 2 
 
 One atom of One molecule of One molecule of 
 
 Carbon, Oxygen. Carbon dioxide, 
 
 12 32 44 
 
 parts by weight. parts by weight. parts by weight. 
 
 44 44 
 
 And likewise, when iron is burned, there is formed an oxide 
 whose composition is expressed by the formula, Fe 3 O 4 ; (to 
 this substance the chemical name ferroso-ferric oxide is 
 applied). 
 
 So when sulphur is burned, sulphur dioxide is formed 
 (SO,). 
 
 In this case the chemical change is represented by the fol- 
 lowing equation : 
 
 S -f- O 2 SO 2 
 
 One atom of One molecule of One molecule of 
 
 Sulphur. Oxygen, Sulphur dioxide, 
 
 32 32 64 
 
 parts by weight. parts by weight. parts by weight. 
 
 64 64 
 
 Ozone. 
 
 * 
 
 Ozone is a peculiarly active form of oxygen. . It is believed 
 to have the formula O 3 , while ordinary oxygen has the for- 
 mula O Q . Now the ozone easily parts with one atom of 
 oxygen, which in its nascent or uncombined state is ready 
 to combine at once with a great many substances. Under 
 these circumstances it manifests the same anomalous features 
 as those described under hydrogen dioxide (see page 124) ; 
 that is, it tends to add oxygen to certain substances and to 
 withdraw oxygen from others. 
 
 Ozone is produced in many ways, one of the best being 
 
120 CHEMISTRY. 
 
 the steady discharge of what is called machine electricity 
 through the atmospheric air or pure oxygen gas. The dis- 
 charge, however, must be silent, and not in the form of sparks. 
 
 Ozone is also produced by certain processes of slow oxi- 
 dation ; thus, when a piece of phosphorus is exposed to the 
 air at ordinary temperatures, it gradually but continually 
 oxidizes. This oxidation is always attended by the pro- 
 duction of ozone. 
 
 Ozone is believed to be formed in the atmosphere in 
 minute quantities by the mere process of evaporation of 
 water. 
 
 Properties of Ozone. 
 
 Ozone is a colorless gas at ordinary temperatures, but at 
 very low temperatures it condenses to a steel-blue liquid. 
 It liquefies much more easily than ordinary oxygen does. 
 
 Ozone is an extremely powerful oxidizing agent, instantly 
 forming oxides of certain metals, like silver, that in ordinary 
 air long retain their bright metallic surfaces. It is also a 
 powerful bleaching agent, decomposing and whitening cer- 
 tain vegetable and animal substances with great promptness. 
 Many experiments have been made with the view of employ- 
 ing ozone in bleacheries, for the purpose of whitening cotton 
 and linen goods. No successful results have been reported, 
 notwithstanding the general belief that, in the old methods of 
 grass bleaching, the ozone produced in small quantities by 
 the sun-light and evaporation of moisture was, in fact, the 
 true bleaching agent. 
 
 The molecular constitution of ozone is believed to be that 
 suggested by the expression O 3 or, 
 
 a multitude of most ingenious experiments having shown 
 that ozone is merely a peculiarly arranged group of oxygen 
 atoms. 
 
OXYGEN. 
 
 121 
 
 Allotropism. 
 
 Chemists know several other elements capable of more 
 than one modification : thus sulphur is capable of at least 
 three modifications, possessing three different sets of proper- 
 ties ; pure phosphorus is known in two separate modifications 
 possessing different properties ; the diamond, graphite and 
 charcoal are three modifications of the element carbon. 
 
 All these substances are designated as allotropic, and the 
 abstract property of chemical elements by virtue of which 
 they are capable of such varied forms is called allotropism. 
 
 FIG. 32. Hydrogen gas, generated by use of zinc and sulphuric acid, is then passed 
 through a drying tube containing calcic chloride (CaCl 2 ). By the act of combustion 
 the union of the dried gas with oxygen of the air produces drops of water. 
 
 First Compound of Oxygen with Hydrogen Water. 
 
 It has already been shown that the hydrogen escaping from 
 a suitable tube may be lighted in the nir. If the burning jet 
 is introduced into oxygen gas the same combustion proceeds, 
 only with greater energy. In either case there is produced a 
 compound of hydrogen and oxygen. This compound is repre- 
 sented by the formula H 2 O, a formula representing no other 
 than the familiar substance water. At the moment of combus- 
 tion of hydrogen very great heat is generated. (See p. 65.) In 
 
122 
 
 CHEMISTRY. 
 
 fact, a pound of hydrogen, upon burning in pure oxygen, yields 
 about four times as much heat as a pound of pure carbon 
 does in burning under the same favorable conditions. Indeed, 
 the pound of hydrogen, when in combustion, yields more heat 
 
 FIG. 33. Apparatus for analysis of water by use of the galvanic battery. 
 
 than a pound of any other substance known. On account of 
 this heat the water resulting from the burning hydrogen at 
 first floats off in the air in the form of vapor ; but if the 
 hydrogen flame is brought in contact with some cooling sur- 
 face, the water formed condenses in drops upon it, and thus 
 it may be readily recognized as in its ordinary form. 
 
 A great multitude of experiments show that the composi- 
 tion of water is as follows : 
 
 
 Parts by weight 
 
 Parts by bulk. 
 
 Atoms. 
 
 Hydrogen 
 
 2 
 
 2 
 
 2 
 
 Oxygen 
 
 16 
 
 1 
 
 1 
 
 The composition of water, as displayed in the foregoing 
 table, has been demonstrated by analysis, this word meaning 
 " the process of taking apart." Thus by chemical influences 
 
OXYGEN. 
 
 123 
 
 a portion of water may be subdivided into its constituents 
 and their amounts determined. On the other hand the com- 
 position of water has also been made out by synthesis, this 
 word meaning " the process of putting things together." In 
 this latter case, by putting together what are believed to be 
 the proper proportional amounts of hydrogen and oxygen 
 to form water, and then upon using some suitable means for 
 bringing these things into a state of true chemical combina- 
 tion, it has been found that they do, in fact, combine to form 
 water, and in the proportions already given in the table. 
 
 FIG. 34. Apparatus devised by Dumas for determining the composition of water. 
 
 Second compound of Oxygen and Hydrogen Hy- 
 drogen Dioxide. 
 
 There are certain circuitous processes by which a com- 
 pound of oxygen and hydrogen, very different from water, 
 may be produced. This compound has the formula H 2 O 2 , 
 and is called hydrogen dioxide. Its molecular constitution 
 is represented by the expression, H O O H. It is a 
 colorless liquid, somewhat like water, only thicker, being one 
 and a half times as heavy as water. It easily decomposes, 
 giving up a single atom of oxygen in an active condition. 
 Curiously enough, the oxygen so liberated acts at different 
 times in ways that at first seem to be quite contradictory ; 
 indeed they could not be well explained when the phenome- 
 na were first observed. 
 
 First. The oxygen so liberated tends to combine directly 
 with many oxides producing higher oxides. 
 
124 CHEMISTRY. 
 
 Second. The oxygen liberated by hydrogen dioxide tends 
 to withdraw oxygen from certain other oxides. 
 
 The modern molecular theory of chemical compounds af- 
 fords an easy and adequate explanation of these phenomena. 
 This theory, as has already been pointed out, holds that the 
 elementary atoms rarely remain single : they prefer the com- 
 bined form. So, then, the single atom of oxygen liberated 
 from the molecule of hydrogen dioxide easily attacks certain 
 substances to combine with them, its affinities being stronger 
 in its single condition than when as in ordinary oxygen it 
 exists in the molecular form represented by the symbol O 2 . 
 In this latter form the affinities of the two atoms of oxygen 
 are partly satisfied by combination with each other. On the 
 other hand, when the single atom of oxygen, liberated by a 
 molecule of hydrogen dioxide, deoxidizes substances, it does 
 so on account of the affinity of this single atom of oxygen for 
 another atom of oxygen, and with the intent to form a more 
 stable molecule represented by the formula O 2 . 
 
 Nascent State. 
 
 The oxygen liberated from hydrogen dioxide is called 
 nascent oxygen (meaning just born, from the Latin word 
 nascor, to be born.) 
 
 This is not the only way of producing nascent oxygen, nor 
 is oxygen the only substance that exists in the nascent form 
 characterized by unusually active powers. 
 
 The nascent state has long been recognized as a peculiar 
 one, and the molecular theory affords a satisfactory expla- 
 nation of phenomena before inexplicable. 
 
 Uses of Hydrogen Dioxide. 
 
 Hydrogen dioxide possesses marked bleaching powers, and 
 notwithstanding its comparatively high cost a solution of it 
 in water has been brought into commerce and is used for 
 certain delicate bleaching operations ; among these may be 
 mentioned the whitening of the paper of books and engrav- 
 ings that have become stained or dingy with age. 
 
OXYGEN. 
 
 125 
 
 The Compound Blowpipe. 
 
 The fact that enormous heat is developed when hydrogen 
 burns was known long ago, and it gave rise to the invention 
 of a contrivance for utilizing it. This has taken the form of 
 
 FIG. .35. Flame of the oxy-hydrogen blowpipe directed upon a crucible in a furnace 
 of lime. 
 
 the apparatus called the compound blowpipe, also the oxy- 
 hydrogen blowpipe. 
 
 This blowpipe, as usually constructed, has a single jet or 
 tip, to which there is conveyed by separate tubes, on the 
 one hand oxygen, on the other hand hydrogen. The gases, 
 
126 CHEMISTRY. 
 
 when lighted, give rise to a flame yielding but little light, but 
 of intense heating power. Many difficultly fusible metals, 
 such as iron, for instance, melt like wax before it, while others, 
 like lead and zinc, boil and vaporize beneath its fervent 
 breath. It must not be looked upon, however, as a mere 
 chemical toy ; it has some uses in the arts. Of these one of 
 the most prominent is its application to the melting and refin- 
 ing of the ores and alloys of platinum, substances which no 
 ordinary furnace can liquefy. 
 
 For purposes of this sort a special furnace or crucible must 
 be provided, and it must be constructed of some substance 
 that is itself practically infusible. Such a material is found 
 in quicklime (calcic oxide, CaO), for this substance does not 
 melt under the influence of any known contrivance for pro- 
 ducing heat. Moreover it does not conduct heat rapidly, 
 and thus any heat applied to the metal within is not subject 
 to serious loss by being conducted away through the walls 
 of the vessel. For melting platinum, then, a furnace con- 
 structed of quicklime and having a cover of the same mate- 
 rial, is employed. A stream of burning gases from a com- 
 pound blowpipe is forced through an aperture in the furnace- 
 cover in such a way as to fall on an interior crucible contain- 
 ing the metal to be melted. 
 
 V 
 
 The Calcium Light. 
 
 Another' interesting application of this blowpipe is found 
 in the lime light, an appliance also known as the calcium 
 light and sometimes as the Drummond light. In this appa- 
 ratus, whatever may be its particular form, the stream of 
 burning gases is directed upon a small block or cylinder of 
 lime. Of course the block becomes highly heated in fact, 
 it assumes a white heat without melting; and while at this 
 temperature it gives out a dazzling light. This light has been 
 utilized by architects and engineers for carrying on impor- 
 tant constructions during the darkness of night. It is also 
 often used in some of the finer forms of the magic lantern, 
 
OXYGEN. 127 
 
 as, for example, in the various stereopticons used in illus- 
 trated lectures. So numerous are the uses of the calcium light 
 in large cities that it has become a regular industry there to 
 furnish the oxygen and hydrogen gases in separate iron 
 cylinders or cans, into which they are pumped under great 
 
 FIG. 36. Drummond light, or calcium light. The flame of the oxy-hydrogen blow- 
 pipe directed against a block of lime renders the latter intensely luminous. 
 
 pressure. (It is true that illuminating gas is sometimes 
 substituted for hydrogen with decided economy in cost, and 
 yet without serious loss of illuminating power.) When the 
 cylinders are in use the stop-cocks are slightly opened, and 
 the gases are under sufficient pressure to flow to the tip of 
 the blowpipe as freely as can be desired. 
 
128 CHEMISTRY. 
 
 Dangerous Explosibility of Mixtures of Oxygen 
 and Hydrogen. 
 
 At this point a warning should not be omitted, for mixt- 
 ures of oxygen and hydrogen gas, whether produced pur- 
 posely or by accident, are capable of very dangerous 
 explosions. Even a soap-bubble, inflated with the mixed 
 gases, and then lighted with a torch, explodes with tremen- 
 dous violence and a loud report. This result is all the more 
 wonderful when the extreme thinness and weakness of the 
 filmy confining envelope are considered. Such explosions are 
 in entire harmony with the various statements already made. 
 For when the two gases combine, the intense heat gen- 
 erated gives rise to a momentary but enormous expansion 
 of the vapor of water produced by the combustion. The 
 greatly expanded vapor strikes the air a sharp and violent 
 blow. In another instant, however, the vapor suddenly cools 
 and condenses to an exceedingly minute drop of liquid water; 
 the air that was previously forced outward immediately falls 
 into the vacancy left, and now a second blow results. It is 
 these two violent shocks, the one following the other in 
 almost instantaneous succession, that produce the report ; 
 and to the same causes must be referred the terribly de- 
 structive results of the accidental explosion of considerable 
 quantities of the mixed gases. It is plain, therefore, that all 
 contrivances destined to employ these gases in close prox- 
 imity must be used with great caution. 
 
 Oxygen as Related to Combustions in General. 
 
 But oxygen is prominent in many other combustions be- 
 sides that of hydrogen. Of course the best known and most 
 common are those in which the ordinary forms of fuel are 
 the things burned. Here generally the principal constituent 
 of the combustible material is carbon. 
 
 Oxygen as Related to Animal Respiration. 
 
 Oxygen performs also one of its most important offices in 
 connection with the process of animal respiration. In the 
 
OXYGEN. 129 
 
 fulfillment of this mission no element is known that can in 
 any way act as a substitute. The gas which is to serve as 
 the breath of life for the humblest as well as the most 
 exalted individuals of the animal creation must possess a 
 combination of qualities truly marvelous when residing in a 
 single substance. Even a brief description of the ways in 
 which it discharges this delicate and manifold duty ought to 
 substantiate the general proposition. 
 
 Oxygen is qualified to sustain respiration by virtue of the 
 exceeding abundance of the atmospheric air; an abundance 
 such that it extends above our heads a distance of forty 
 thousand times the height of a man. Nor are the denizens 
 of the sea forgotten, for oxygen possesses such capacity for 
 dissolving in water that there exists, absorbed in the liquid 
 of the rivers and oceans, enough of this vital gas to furnish 
 breath for all the finny tribes. 
 
 Again, the oxygen, so violent in its combinations, is yet 
 bland enough to pass through all the delicate passages lead- 
 ing into the lungs without exciting the throat to the slight- 
 est cough; to filter through the fine membranes of the lungs 
 without doing an injury; to saturate the blood, and to flow 
 to every tissue and cell of the body, and not only do no 
 harm but every-where accomplish a reviving work. It per- 
 forms throughout the animal frame a well-regulated but no 
 inconsiderable combustion. Indeed the body of a living 
 animal may be properly looked upon as a kind of furnace, 
 taking in air whose oxygen shall sustain the combustion of 
 worn-out parts. Nay, more; these as they burn do in their 
 very death aiford as their final contribution that warmth and 
 glow which maintains the animal temperature at the vital point. 
 
 While carrying out the important functions just referred 
 to, oxygen produces several gaseous substances, each of 
 which, as if under the constant direction of an ever-watchful 
 barometer, maintains its proper bulk and pressure, so as to 
 do no injury to the most delicate capillary of a vein or to 
 the tender walls of the smallest chambered cell of the lungs. 
 With each breath exhaled from the * system, the blood, and 
 9 
 
CHEMISTRY. 
 
 thence the lungs, discharge the gaseous products of the com- 
 bustion already described; plainly they do it somewhat in 
 the same manner as a chimney does in its proper action, only 
 the lungs do their work in a far more perfect way. 
 
 The parallelism is not strained here, for the burning of 
 the animal tissue in the body gives rise principally to the 
 production of the gas called carbon dioxide and the vapor of 
 water, just as when a fagot burns in the chimney-place the 
 carbon and the hydrogen of the wood oxidize into the self- 
 same products, both of which are wafted up the flue and out 
 into the great ocean of atmosphere beyond. 
 
 READING REFERENCES. 
 
 Gases, Liquefaction of. 
 
 Cailletet, L. Aunales de Cliiraie et de Physique. 5 Ser. xv, 132. 
 
 Chera. News, xxxvii, 11. 
 
 Cailletet, L. Science, vi, 21. 
 
 Coleraan, J. J. Chem. News, xxxix, 87. 
 
 Pictet, R. Annales de Chimie et de Physique. 5 Ser. xiii, 145. 
 
 Chem. News, xxxvii, 1, 23, 83. 
 
 Roscoe and Schorlemmer. Chemistry. New York. 1878. ii, pt. II, 
 516. 
 
 Schutzenberger, P. Traite de Chimie Geuerale. i, 25. 
 Priestley, Joseph. 
 
 Brougham, H. Lives of Men of Letter?, etc. p. 402. 
 
 Amer. Chemist, iv, 362-441 ; v, 11-35. 43, 210. 
 
 Ozone or Active Oxygen. 
 
 Roscoe and Schorlemmer, A Treatise on Chemistry, i. 194. 
 
WATER. 131 
 
 XVI. 
 
 WATER. 
 
 IS the most prominent compound of oxygen, water 
 may properly receive the reader's attention at 
 this time. 
 
 He who stands upon a high cliff and looks out 
 upon the ocean, experiences as one of his strongest impres- 
 sions, that of the boundlessness of the expanse. And it is 
 true that the area of terrestrial waters is very wide, for in 
 the aggregate their waves cover more than three fourths of 
 the earth's surface. But while their superficial extent is so 
 great, their depths are relatively but small. When compared 
 with the diameter of the earth the deepest ocean seems shallow 
 indeed. If the waters of the oceans were dried up, or other- 
 wise wiped away, the roughness of the dry globe would be 
 less relatively than the roughness of an orange. In fact the 
 total amount of water actually existing upon the earth's sur- 
 face is less relatively to the entire mass of the globe than 
 the amount that would remain on an orange after dipping it 
 into a basin of water and then withdrawing it. Notwith- 
 standing these facts, the amount of water is so vast in pro- 
 portion to the littleness of human beings, and it has taken 
 so prominent a part in the phenomena observable by man, 
 and it has been such a powerful agent in the geological eras 
 of the past, that it is not surprising that its properties and 
 history have excited the interest of students and thinkers of 
 all times. In the light of modern chemical knowledge, too, 
 its various offices create an admiration that is heightened 
 the more they are considered. 
 
 The chemical constitution, the characteristics, the proper- 
 ties, and the uses of water, are important chemical topics ; 
 when one considers, further, the varied forms and uses in 
 which this familiar substance is employed in nature and in 
 
132 
 
 CHEMISTRY. 
 
 the arts, a subject is suggested that might well furnish 
 material for a volume. Plainly, then, only a few of its more 
 striking adaptations can be discussed here. 
 
 Importance of Water to Living Beings. 
 
 To living animals and plants water nppears to be abso- 
 lutely indispensable. The reason for this is found not only 
 
 in tlie fact thnt water 
 forms a necessary constit- 
 uent part of most living 
 beings, but also because 
 it serves as a sort of 
 vehicle by virtue of 
 whose properties the vital 
 processes are conducted 
 and through which the 
 vital currents flow. It is 
 easy to understand that 
 if the atmospheric air, 
 which lies wrapped about 
 our globe like a thin veil 
 were suddenly wafted 
 away, animal life would 
 be instantly extinguished. Now water is not less essential 
 than air. Banish water from the earth, and the life of all 
 animal and vegetable beings would instantly take its flight. 
 For the blood, that living tide which courses through the 
 natural gates and alleys of the body, contains water to the 
 extent of nearly 80 per cent, of its weight. Again, pure, 
 unadulterated milk, rich as it is in solid food materials dis- 
 solved or suspended within it, contains not far short of 90 
 per cent, of water. And further, an examination of vegeta- 
 ble products reveals in them a preponderance of water such 
 as would not at first be suspected. Thus the following 
 brief table represents facts so surprising that it is at first 
 difficult to accept them; 
 
 FIG. 37. Egyptian Water-carrier. 
 
WATER. 
 
 Apples contain about 80 per cent, of water. 
 Turnips contain about 90 per cent, of water. 
 Cucumbers contain about 97 per cent, of water. 
 
 Finally, as an extreme example among the kingdoms of 
 life, it may be mentioned that some forms of jelly-fish, as 
 taken from their appropriate home in the ocean, have been 
 found to contain not less than 99 9-10 per cent, of water.* 
 
 The extraordinary and indeed incredible proportion of 
 water in living beings is associated with the numerous, 
 varied, and even apparently contradictory offices to be per- 
 formed by it, and the fitness of water to fulfill these 
 requirements is referable further to the curious and interest- 
 ing properties with which it is endowed. But it is so 
 familiar to every one, and so bland in its action in its rela- 
 tion to most well-known substances, that the ordinary 
 observer fails to recognize these properties and their marvel- 
 ous adaptations. 
 
 One of the properties most appropriate for presentation 
 in this connection is the power water possesses of dissolving 
 gases. It is capable of storing up within itself, concealed 
 from human view, almost every gas with which it comes in 
 contact. It displays this power upon (he atmospheric air, 
 not only in its better known relations to man and the higher 
 animals, but also as respects the humbler population of the 
 globe. It will be seen by and by that the air consists in the 
 main of a mixture of two gases very different in their 
 properties. One is oxygen, the sustainer of animal respira- 
 tion ; the other, nitrogen, the inactive substance existing in 
 the air as a mere diluent of the active oxygen. Xow water 
 possesses a very curious relation to these gases; it dissolves 
 a larger proportion of oxygen than of nitrogen. By reason 
 of this property it acts upon the atmospheric air with a 
 selective effect highly suggestive of intelligent plan. For 
 the gas it selects to dissolve in larger proportional quantity 
 is oxygen the one absolutely needed to take the principal 
 
 * COOKE, JOSIAH P. : Religion and Chemistry. New York, 1864. p. 148. 
 
134 
 
 CHEMISTKY. 
 
 part in supporting the respiration of the countless millions 
 of fishes that make their natural homes in all great bodies of 
 water. 
 
 Terrestrial Circulation of Water. 
 
 Water is the chief liquid of our great globe. And it car- 
 ries on here a continued and beneficent double circulation 
 which may be properly likened to that of the living animal and 
 plant, except that it proceeds on the cosmical scale. The one 
 portion of this circulation may be described as starting in the 
 depths of the ocean ; thence permanent currents continually 
 
 flow in certain 
 definite direc- 
 tions and ulti- 
 mately regain 
 their starting- 
 place. These 
 currents c o n- 
 tribute to make 
 the seas the 
 highways of na- 
 vies even more 
 c omple t ely 
 
 than they would be if the waters were always at rest. A yet 
 more striking circulatory movement is that initiated by the 
 volumes of moisture which rise by constant evaporation from 
 the temperate as well as the tropical seas. This water, 
 ascending into the higher atmosphere, is carried by currents 
 of the air hither and thither and over the land, where by 
 mountain ranges, or other natural means adequate to this 
 purpose, it becomes precipitated into a solid or liquid form. 
 In this condensed form it is recognized as beneficent when 
 it is in cloud masses, which delight mankind with the purity 
 of their fleecy whiteness or the beauty of their gorgeous 
 coloring, as well as when it is in the form of showers which 
 refresh the thirsty earth, or as the snow which protects it. 
 The rain and snow supply the numberless rivulets that contrib- 
 
 FIG. 38. Water in the form of cumulus clouds. 
 
WATER. 1S5 
 
 ute to make up rivers, and these flow joyfully to the ocean 
 and, mingling in its waters, return to the source from which 
 they came. Thus has been pictured in brief an outline of 
 the circulation previously suggested. 
 
 Water in the Solid Form. 
 
 Again, certain properties of water other than these 
 already stated are worthy of presentation. Perhaps it is not 
 inconsistent with the truth to say that they are even more 
 plainly beneficial. Thus, in the form of snow, water appears 
 at first sight to be an emblem of cold. But when it falls 
 upon the earth it becomes a mantle or coverlet, which pro- 
 tects the soil from the chilling effects of the wintry season 
 and from that rapid loss of heat by radiation off into space 
 which the fields would suffer without this protective coating. 
 And so ice, as it forms on the surface of lakes and ponds, 
 manifests several remarkable properties. Of these only two 
 will be discussed here. They are both due to its power 
 of expanding at the moment of solidification. Most per- 
 sons make acquaintance with this characteristic of water by 
 the inconvenient bursting of pitchers and pipes, recognized 
 as a disagreeable attendant upon the winter's cold. When 
 looked upon with more fully instructed eyes, however, it is 
 discovered to be one feature of a remarkable system which 
 results in great benefit to the inhabitants of the earth. For 
 it is plain that as water in freezing expands, it thereby 
 becomes relatively lighter. On this account ice floats in 
 water, whereas solid substances generally sink in liquid mat- 
 ters -of their own kind. Now the ice formed upon lakes in 
 the winter stays at the top, and thus protects the water 
 below from the chill of the colder air; so it prevents the 
 lakes from becoming uninhabitable to the fish. The same 
 property prevents a lake from becoming a mass of solid 
 from the bottom upward, as would be the case if the ice, 
 upon freezing, went to the bottom. The summer's sun 
 would hardly be capable of thawing the solid masses so 
 
136 CHEMISTRY. 
 
 formed. This same curious fact the expansion of ice at 
 the moment of its formation contributes to the fertility of 
 the soil. Thus the water that penetrates the crevices of 
 rocks expands upon freezing, chipping off those rocks, in 
 fact pulverizing them little by little, and so conveying fresh 
 and valuable materials to the earth's soils. 
 
 Water as Affecting Climate. 
 
 Further, the relations of water to heat are very interest- 
 ing. " The general aqueous circulation of the earth is a 
 great steam-heating apparatus, with its boiler in the tropics 
 and its condensers all over the globe. The sun's rays make 
 the steam. And wherever dew, rain or snow forms, there 
 heat, which came originally from the sun, and which has 
 been brought from the tropics concealed in the folds of the 
 vapor in the form of latent heat, is set free to warm the 
 less favored regions of the earth. [Latent heat is heat either 
 concealed or else suddenly made manifest at the moment 
 of change of a substance from one of the three states of 
 matter, solid, liquid, or gaseous, to another.] This apparatus 
 in nature, although so much simpler and working without 
 pipes, iron boiler, or radiator, is exactly the same in princi- 
 ple as the steam heaters " which may be seen at work in 
 many large buildings.* In other words, when water is 
 changed into vapor in the tropics, heat is not only requisite 
 to the operation, but a definite quantity of heat is actually 
 stored up within the vapor so produced. On the other 
 hand, whenever in some cooler parts of the globe this same 
 portion of vapor condenses into the form of liquid, that 
 heat that was stored within it at the tropics is immediately 
 evolved, and contributes materially to the warmth of the 
 region where condensation takes place. Nay, more; if the 
 water, instead of falling as rain, falls as snow a still larger 
 amount of heat is by this means given out into the atmos- 
 phere. This last statement is insensibly substantiated by 
 
 *COOKE, JOSIAH P. : Religion and Chemistry. New York, 1884. p. 135. 
 
WATER. 18? 
 
 the expression often heard in winter, "the weather is too 
 cold for snow." This common expression, translated into 
 scientific language means, " if snow were already condensing 
 in the upper air, and ready to fall, the heat given out by it 
 would have reached us in advance." 
 
 It is not only with respect to those changes taking place 
 when the vapor of water changes to the liquid or the solid 
 form that its heat relations are beneficial to mankind. No 
 lake can change one degree in temperature that is, grow 
 warmer or cooler without at the same time exercising a 
 contrarywise influence upon the air about it, and thus a 
 regulating one. 
 
 This is by virtue of that property of water called its spe- 
 cific heat. (Specific heat is the relative amount of heat 
 concealed or else liberated when a body undergoes a change 
 of temp-erature.) 
 
 In explanation of this declaration the following state- 
 ments may be made: When, in the intensely hot days of 
 summer, a lake or any mass of water becomes influenced by 
 the high temperature, of course its waters become warmer. 
 But it is a curious fact that it takes more heat to raise the tem- 
 perature of water one degree than it does to raise the tem- 
 perature of the adjoining land one degree or in fact to raise 
 any other substance known one degree. Thus it appears 
 that a given amount of heat applied in a summer day to a 
 lake will be absorbed within the waters of that lake without 
 raising the temperature of those waters to the extent that 
 might be expected. So, then, in hot weather the lake 
 becomes an equalizer of temperature with a tendency in the 
 opposite direction, that is to cool the air about it. Now in 
 cold weather it becomes equally beneficial, only, as might be 
 expected, in the opposite direction. Thus the store of heat 
 retained by the liquid water is given out as the lake cools. 
 For just as the water in order to rise one degree in tempera- 
 ture requires, and indeed, absorbs more heat than any other 
 substance known, so naturally the same water, in cooling 
 one degree in temperature, freely gives out the amount of 
 
138 CHEMISTRY. 
 
 heat it had previously stored within itself, which, as has been 
 said, is greater than that stored up by any other substance 
 known. 
 
 The remarks thus far made on water as influencing cli- 
 mate relate to it chiefly when in the liquid form, and in 
 considerable bodies on the surface of the earth. 
 
 The atmosphere above our heads contains large quantities 
 of water in the aggregate. 
 
 This water is in the form of vapor, it is true, but notwith- 
 standing this condition it is capable of exerting a marked 
 and important effect on climate, retaining the heat of the 
 sun in a manner more fully described in a later chapter. 
 (See page 180, and also reading reference on page 183.) 
 
 Water as a Working Contrivance. 
 
 When the moisture of the tropical ocean is taken up into 
 the air by evaporation, the sun has thereby done a truly stu- 
 pendous amount of work. For has it not lifted up high into 
 the atmosphere an enormous weight of this liquid material ? 
 Now as the vapor is wafted over the land preparatory to 
 falling as rain, it has acquired a position in which it may do 
 a great amount of work for human uses ; for every rain 
 drop, falling from its lofty position in the air, acquires 
 thereby a momentum which represents a quantity of force, 
 minute in each individual case, but truly vast in the 
 aggregate. Of this sum total but a small portion is 
 employed for man's industrial uses ; only a minute frac- 
 tional part is harnessed to the wheels that grind his food 
 or weave his clothing or transform the trees of the forest 
 into his habitations ; yet the amount he does so employ 
 compelling it to do his work for him represents an enor- 
 mous total quantity. All this work done, as well as all that 
 might be done by the vast quantities of water allowed to 
 escape and violently run to waste, is referable back again to 
 the sun of the tropics, which has been enabled, by reason 
 of the wonderful properties of water, to store up all this 
 power within it. 
 
WATER. 130 
 
 In view of what has been said, the sun and water of the 
 tropics may be compared not inappropriately to the chief 
 artificial contrivances used in modern times for generating 
 and applying mechanical power boiler and engine. As an 
 ordinary steam-boiler imparts to water the expansive and 
 working power of steam, and again the ordinary steam- 
 engine utilizes this steam power so that it may be directly 
 applied to the labor of man's workshops, so the sun of the 
 tropics lifts the water of the ocean high up into the air, and 
 thus may be likened to the boiler ; while the rapidly run- 
 ning brooks may fitly represent an engine in motion, ready 
 to actuate any machine to which by proper appliances it 
 may be attached. 
 
 Kinds of Water. 
 
 The kinds of water found in nature differ chiefly in the 
 foreign matters they contain. These matters differ very 
 much in their character. Some are merely suspended, floating 
 in the water; others are invisible, fully dissolved. They differ 
 also in their chemical nature, as is evidenced by the different 
 remedial substances existing in mineral spring-waters of 
 different places. 
 
 Reference has already been made to the well-established 
 fact that most of the water of our globe is all the time mov- 
 ing onward in what may be called a natural circuit. Now 
 the character of any given natural water is dependent mainly 
 upon the part of the natural circuit at which the sample of 
 water under consideration is arrested. 
 
 The circulation thus referred to may be briefly represented 
 in four stages. 
 
 The first stage is that in which the water is rising as vapor 
 in the atmosphere. 
 
 The second stage is that in which the water is falling to 
 the earth in rain. 
 
 The third stage is that in which the water flows down- 
 ward over the land in brooks and rivers. 
 
140 CHEMISTRY. 
 
 The fourth stage is that in which the water rests in the 
 hollow places of the globe, as the great oceans. 
 
 Of course it is easily seen that this circuit is ever repeated, 
 the evaporation taking place at the surface of the sea being 
 the greatest source of moisture in the atmosphere. 
 
 But while most of the moisture evaporated from the ocean 
 and condensed as rain returns by the rivers to the great oceans, 
 a part of it is diverted where the surface configuration of 
 the earth gives rise to 'small hollows not connected with the 
 oceans and salt lakes are thus formed. They are virtually 
 little oceans. 
 
 Again, in some cases, falling rain, instead of proceeding 
 directly toward the ocean, strikes upon portions of the earth 
 having considerable porosity, and then it sinks below the 
 surface and takes such subterranean course as the strata it 
 meets dictate. In this latter case, however, the subterranean 
 waters often come to the surface again through natural fis- 
 sures, as in the case of mineral springs, or by artificial open- 
 ings, as in the case of wells. 
 
 There has thus far been briefly indicated in their relations 
 to each other, and as parts of the natural circulation, rain- 
 water, brook or river-water, sea-water or water of salt lakes, 
 and again, as a sort of side branch from the main chief current, 
 mineral spring-water and well-water. 
 
 Rain-water. Rain-water, when it first condenses in the 
 higher atmosphere, must be regarded as perfectly pure water. 
 In falling toward the earth, however, it dissolves, from the 
 gases of the atmosphere, some oxygen, some nitrogen, some 
 carbon dioxide, some ammonia gas. After thunder-storms 
 it also takes from the air some ammonic nitrate (NII 4 NO 3 ) 
 a substance believed to be produced by the influence of the 
 electric discharge upon the elementary gases always present 
 in our atmosphere. 
 
 Of course in the vicinity of large cities, especially those con- 
 taining many manufacturing establishments, rain-water col- 
 lects many other substances. The air of towns imparts to 
 the rain-water spot, and dust, and ashes, and even sulphuric 
 
WATER, 141 
 
 acid, from the coal burned. To these must be added, of 
 course, all those special impurities cast out by the chimneys 
 of special manufacturing establishments, and there must still 
 be added large quantities of organic refuse, cast forth from 
 living animals and dead as well representing in the aggre- 
 gate no trifling amount of organic contamination. 
 
 All this has reference, of course, to rain-water that has been 
 carefully collected. Rain-water, as ordinarily collected from 
 the roofs of a city, is often contaminated from the materials 
 of the roofs as well as by the dust collected upon them. 
 
 While, therefore, the rain-water carefully collected in the 
 open country may be comparatively pure, rain-water col- 
 lected in the city may be quite otherwise. 
 
 River-water. Rivers derive their chief supply of water from 
 direct surface drainage. To this there is sometimes added 
 water that has taken a short underground course and feeds 
 the river through the agency of springs. 
 
 Ordinary river waters in their natural conditions are com- 
 paratively pure. Whatever impurities are in them depend 
 mainly upon the character of the water-shed. Some granitic 
 rocks allow the river-waters flowing over them to come away 
 practically unaffected; again, some sandy soils not only them- 
 selves impart but little impurity, they sometimes act as filters 
 of the water passing through them, removing from it impuri- 
 ties originally contained in it. 
 
 While water of thinly-settled regions derives relatively 
 few impurities, that of densely populated places often receives 
 from farms and human habitations and factories vast amounts 
 of foreign matters, most of them properly considered as pol- 
 luting. 
 
 Sea-water and water of salt lakes. The accumulation of salts 
 in the oceans and in the salt lakes is largely due to the fact 
 that, while the rivers flowing into them are continually carry- 
 ing mineral matters toward them, the water evaporating 
 from them is practically pure. Of course the sea-water of 
 different localities might be expected to contain matters of 
 slightly varying quality because of differences in the terres- 
 
142 CHEMISTRY. 
 
 trial strata furnishing them. They might also be expected 
 to vary in quantity because of differences in the amount of 
 evaporation compared with the flow of river-waters toward 
 them, and also because of the varying influences of oceanic 
 currents. Thus the water of the Mediterranean has about 
 one tenth more mineral matter than the waters of larger 
 oceans a fact which is due partly to the great amount of 
 evaporation, referable to the hot winds from the Great Desert, 
 and also to the limitations upon its circulation, referable to 
 the narrow and comparatively shallow passage at Gibraltar. 
 
 The average composition of sea- water may be stated as 
 follows : 
 
 PER CENT. 
 
 Calcic carbonate (CaC0 3 ) 003 
 
 Magnesic bromide (MgBr 2 ).. . .002 
 Other matters aggregating. . . .025 
 
 Water 96.470 
 
 Sodic chloride (NaCl) 2.700 
 
 Potassic chloride (KC1) 070 
 
 Magnesic chloride (MgCl a ), . . .360 
 
 Magnesic sulphate (MgS0 4 ). . .230 100.000 
 
 Calcic sulphate (CaS0 4 ) .140 
 
 Spring-water. The water of mineral springs differs from 
 ordinary well-water in that while it contains usually very 
 small amounts of organic matters that is, animal and vege- 
 table matters it often contains very large amounts of min- 
 eral matters. 
 
 It is also generally charged with gases. The most com- 
 mon gas thus present is carbon dioxide, but some spring- 
 waters contain oxygen, nitrogen, sulphuretted hydrogen and 
 hydrocarbons. 
 
 The large amount of mineral matters present in true min- 
 eral waters is due partly to the fact that the waters have 
 filtered to great depths in the earth and have come in con- 
 tact with considerable deposits of mineral matter, and this 
 too, with the water under so great pressure as to favor solv- 
 ent action. 
 
 Again, some of the gases, notably carbon dioxide, held by 
 mineral waters increase very largely the solvent power of the 
 water. The spring- waters of the civilized world vary very 
 much in their remedial influences because the substances con- 
 
WATER. 143 
 
 tained by the waters vary very much. Partly on this ac- 
 count classification of them is difficult; they are capable, 
 however, in a general way, of being classified according to 
 the acid radicles predominating, &s, first, carbonated; second, 
 sulphuretted and sulphatic ; third, chlorinated ; fourth, sil- 
 icious. 
 
 Again, they may be classified according to the metallic 
 radicles prevailing in them, as, first, alkaline ; second, magne- 
 sian ; third, calcareous ; fourth, chalybeate (when containing 
 iron in abundance). A given water may, perhaps, be classed 
 under both groups at once ; thus it might be said to be at 
 once carbonated and alkaline. 
 
 Well-water. Well-waters have already been classified as 
 belonging to the same group as mineral spring-waters. The 
 well-waters, however, pass through a smaller quantity of 
 earth and so take up less mineral matter. 
 
 When wells are situated in populous districts their waters 
 often become directly or indirectly impregnated with danger- 
 ous impurities, such as animal and vegetable matters which 
 have drained into them from cesspools or sewers. 
 
 If such waters are used for drinking or cooking they are 
 often extremely dangerous ; many epidemics of certain classes 
 of diseases, such as typhoid fever and cholera, are directly 
 traceable to the domestic use of water contaminated by sew- 
 age. 
 
 Deep wells, called in general artesian wells, have sometimes 
 yielded waters resembling mineral spring-water. Sometimes, 
 however, such water has been found comparatively free from 
 mineral matter, and, indeed, from organic matter, so as to be 
 well fitted for drinking and cooking purposes. It seems, in 
 fact, as if the water had undergone an entirely succcessful 
 natural process of filtration. 
 
144 CHEMISTRY. 
 
 XVII. 
 
 SULPHUR. 
 
 jULPHUK, in its aggregate in the earth, is by no 
 means an abundant element. Thus, its quantity 
 is far inferior to that of oxygen, as is strikingly 
 illustrated by the diagram already presented. 
 (See page 17.) Yet sulphur was recognized by human be- 
 ings thousands of years before oxygen, which it has already 
 been stated was discovered in 1774. The comparative late- 
 ness of the discovery of this latter element, now known to be 
 that one which predominates largely over all others in the 
 earth, is due partly to the fact that free oxygen almost in- 
 variably exists in gaseous form, and that the idea, or notion, 
 of gas is one of recent growth. The fact that sulphur was 
 recognized so much earlier is due to many circumstances. 
 First. It is found in the earth in the solid condition a 
 form at once tangible and easy of recognition. Second. Its 
 yellow color helps to render it noticeable. Third. It exists 
 in the earth in countries which have long been the abode of 
 civilized beings. Thus it was early recognized in Italy. 
 Fourth. It occurs in deposits of such a character that it can 
 be readily obtained in a comparatively pure form from them. 
 Fifth. It possesses remarkable properties some of which 
 would be easily detected even by savage peoples, while 
 others have for centuries excited great interest in the minds 
 of students of alchemy and chemistry. One of those prop- 
 erties is the ease with which it assumes a liquid form that 
 is, melts when slightly heated. Another is the readiness 
 with which it takes fire and burns in the air. A third, 
 closely connected with the foregoing, is the striking blue 
 flame produced when it burns. Still another, and not less 
 noticeable one, is the choking and disagreeable odor attend- 
 ant upon this combustion. 
 
PLATE VI. Sketch illustrating the process of refining sulphur. 
 
 (See Chap. XVII.) 
 
SULPHUR. 145 
 
 Finally may be mentioned a circumstance which for a long 
 time contributed to make it peculiarly interesting to the 
 alchemist, if not to ordinary men: this is the fact that when 
 sulphur is in the pure form it may be burned away without 
 leaving any ashes. In this respect it differs from most other 
 combustible materials; and this property created the impres- 
 sion that sulphur is a sort of principle of fire, and that it 
 somehow exists in all combustible bodies. Indeed it is only 
 for about a hundred years that sulphur has been classified as a 
 distinct elementary form of matter. It is not intended to 
 indicate here that the strong interest of the alchemists in 
 sulphur was mainly referable to the circumstances of its 
 combustibility. Its power of combination with the metals 
 was well known to them, and was recognized as a subject of 
 practical importance and one worthy of careful study and 
 thought. 
 
 Natural Sources of Sulphur. 
 
 The principal supply of sulphur for commerce is obtained 
 from the volcanic districts of the island of Sicily. Here in 
 fact there are more than two hundred distinct establish- 
 ments for production of the substance, and they are capable 
 of yielding about two hundred million pounds of it per year. 
 
 The fact that sulphur is easily and widely recognized in 
 the earth has already been dwelt upon. But it occurs in 
 nature in a great variety of forms. The first and most strik- 
 ing form is that of free and uncombined sulphur. In this 
 condition it occurs either as masses or as fine powder. Some- 
 ,, times these materials possess the well-known and easily 
 recognized yellow color of sulphur; sometimes, however, the 
 color is white, or otherwise disguised, by reason of some pe- 
 culiarity of the sulphur itself or else because of the admix- 
 ture of foreign substances. 
 
 Deposits of sulphur occur in the most considerable quanti- 
 ties in the neighborhood of either active or extinct volcanoes. 
 Thus sulphur earth occurs near Vesuvius and ^Etna, also in 
 the ricinity of the volcanoes of Iceland, in the crater of Po- 
 10 
 
146 CHEMISTRY. 
 
 pocatapetl in Mexico, in Central America, and in the Sand- 
 wich Islands. 
 
 In gathering sulphur from Popocatapetl a company of 
 laborers go down into the crater. There they gather the 
 sulphur and place it in large buckets, in which it is hoisted 
 to the summit. They work continuously for about a month, 
 eating and sleeping in the crater, until, completely exhausted 
 by the arduous labor and the sulphurous fumes of the volcano, 
 they are hoisted out and rest while others take their place. 
 
 In the region of some extinct volcanoes the soil is impreg- 
 nated with sulphur to the depth of twenty or thirty feet, and 
 such soil is therefore a convenient source of the element. 
 
 Purification of Natural Sulphur Ores. 
 
 In obtaining sulphur from the earth for commercial pur- 
 poses two simple processes are resorted to. By the first 
 method, masses of the sulphur earth are heaped up into a 
 pile, in connection with a small amount of fuel and over a 
 shallow depression in the earth. Upon setting the mass on 
 fire considerable quantities of sulphur escape combustion, 
 and so melt and run down to the ground below the heap. 
 When the fire is extinguished, the sulphur that collected 
 beneath may be secured in a form now only slightly impure. 
 
 The second method of purification of the earth is still con- 
 ducted in Sicily in the following crude manner, though this 
 is quite an improvement upon that just described : A 
 slightly inclined plane of masonry is built upon the ground. 
 Around the edges of this plane a low wall is erected. At 
 the lower side of the plane the wall is perforated. Upon the 
 surface of the plane large masses of sulphur earth are care- 
 fully piled up so as to form a well-built heap. When it 
 reaches the proper height its outside is covered all over, first, 
 with small fragments of the same kind of earth, and then 
 with its fine dust. Sulphur at the lower portion of the heap 
 is then set on fire at several points. The heat from the 
 sulphur that burns melts other portions of it, which then 
 trickle down the spaces between the masses of rock. This 
 
SULPHUR. 
 
 147 
 
 melted material, finding the bottom of the pile, runs freely 
 to the lowest portion of the platform, then through the per- 
 forations and out into wooden boxes placed to receive it. 
 The heap burns for two or three weeks, at the end of which 
 time the operation is finished. When the mass is cool it is 
 torn down, and a similar pile is erected from fresh portions 
 of the sulphur earth. The objectionable features of this proc- 
 ess are at least four. First, the consumption of sulphur as 
 fuel is a wasteful one. But in reply it may be said that no 
 
 FIG. 39. CaZcarone, or heap of burning mineral from which sulphur is obtained. 
 
 cheaper fuel is accessible where this manufacture is carried 
 on. Again, the great volumes of sulphur dioxide given out 
 by the burning calcaroni as the heaps are called are inju- 
 rious to the health of the workmen. Further, these same 
 products exercise a very destructive effect upon all vegeta- 
 tion in their vicinity. In fact, on this account the Italian 
 Government has provided by law that this work shall not be 
 carried on at all between July 1 and December 31. Finally, 
 the method is least successful with the richest ores, for they 
 readily break down into powder which it is difficult to util- 
 ize in the calcaroni. 
 
148 CHEMISTRY. 
 
 A new and greatly improved method, and one which over- 
 comes all the objections above cited, has recently been intro- 
 duced. In this, the ore is placed in perforated metal baskets 
 and then immersed in tanks containing hot solutions of 
 calcic chloride in water. Under these conditions the sulphur 
 melts out from its ore and falls to the bottom of the tanks 
 whence it is drawn out by stop-cocks in a comparatively pure 
 form. 
 
 Sulphur is generally subjected to a still further purifica- 
 tion. This is conducted somewhat as follows: The crude 
 sulphur, being melted in a suitable retort and over a coal 
 fire, changes into vapor and passes into an apartment con- 
 structed of stone or brick, and prepared for the purpose. In 
 this apartment the sulphur at first condenses on the walls as 
 minute yellow crystals, or powder, called flowers of sulphur. 
 When the first charge of sulphur in the retort has been com- 
 pletely vaporized a new supply is allowed to run in, this 
 time in the liquid form, from a small heater placed above the 
 retort. The waste heat from the furnace melts the sulphur 
 in the heater, from which it flows into the retort (by means 
 of the tube shown in Plate VI). When a sufficient amount 
 of flowers of sulphur has collected in the chamber the fire is 
 extinguished. The purer product is then removed. After- 
 ward the whole operation is repeated. 
 
 The refining may be conducted so that the temperature of 
 the condensing apartment may rise considerably; in this case 
 the vapor in it condenses to the liquid form. This liquid 
 may be drawn off at the base of the chamber into a small 
 receiver, from which it is ladled into molds, which give it 
 the form of cylinders known in trade as roll brimstone. 
 
 Natural Compounds of Sulphur. 
 
 Sulphur is also found in the earth in the form of certain 
 chemical compounds. Some of these are very widely dis- 
 tributed. They may be divided into two classes. 
 
 The first class whose representatives are by far the more 
 
SULPHUR. 149 
 
 abundant includes the metallic sulphides, that is, pom- 
 pounds formed by the direct union of sulphur with some 
 metallic substance. As examples of compounds of this class 
 we mention: 
 
 Sulphide of iron (commonly called iron pyrites, and having 
 the formula FeS 2 ). 
 
 Sulphide of lead (commonly called galena, and having the 
 formula PbS). 
 
 Sulphide of zinc (commonly called blende, and having the 
 formula ZnS). 
 
 Sulphide of mercury (commonly called cinnabar, and hav- 
 ing the formula HgS). 
 
 Many other examples of similar import might be given, 
 for it is a well-known fact that most of the heavy metals 
 occur in the earth in combination with sulphur. 
 
 The other class of compounds also containing sulphur 
 combined with the metals has usually oxygen in addition. 
 Two examples of this class may be given here ; calcic sul- 
 phate (commonly called anhydrite, and having the formula 
 CaSO 4 ); also baric sulphate (commonly called heavy spar, 
 and having the formula BaSOJ. 
 
 Sulphur is very widely distributed in animal and vege- 
 table matters. In these it exists, not as an uncombined ele- 
 ment, but in union with others. Indeed such compounds 
 have many other elements besides the sulphur, and they are 
 characterized by decided complexity of structure. But sul- 
 phur is oftener a component of animal matters than of vege- 
 table. The presence of sulphur in an egg is proved by an 
 experiment of e very-day occurrence that is to say, the 
 silver spoon with which the egg is eaten becomes blackened. 
 This blackening is due to the production of a new compound 
 formed by a true union of sulphur from the egg with a part 
 of the metal of the spoon. In fact the black material is 
 sulphide of silver, and it may be represented by the formula 
 Ag 2 S. A French chemist has estimated that in the body of 
 a human being of ordinary size there exists, in the aggre- 
 gate, not far from one quarter of a pound of sulphur. To 
 
150 CHEMISTRY. 
 
 this he adds the curious estimate that the entire human 
 population of France may be represented as containing not 
 far from nine millions of pounds of sulphur. 
 
 Chemical Properties of Sulphur. 
 
 The chemical properties of sulphur may be said to be its 
 most important and interesting ones. That it has a wide 
 range of chemical aptitudes is shown by the fact that it 
 combines in simple forms of union with a majority of the 
 elements known. Thus it has strong affinities for most of 
 the metals. On the other hand it combines with various 
 degrees of attractive force with nearly all the non-metals as 
 well. Evidently, then, sulphur forms a very large number 
 of chemical compounds. While the limits of this work are 
 such as to make it impossible to describe many of them, 
 there are three that may with propriety be briefly discussed 
 in this place, and these are: 
 
 Sulphuretted hydrogen (H 2 S), 
 Sulphur dioxide (S0 2 ), 
 
 Sulphur trioxide (S0 3 ). 
 
 Sulphuretted Hydrogen. 
 
 This substance is a colorless gas. It has an extremely 
 offensive odor; in fact it is a prominent component of that 
 numerous group of gaseous products of decomposition of 
 animal matters that produce the disagreeable smell attend- 
 ant upon the decay of the latter. 
 
 Again, it is found in the waters of certain natural sulphur 
 springs, and it is a remedial agent of considerable value 
 when properly applied externally or when taken into the 
 stomach. When received into the lungs, however, it is de- 
 cidedly poisonous. 
 
 A considerable number of simple experiments may be 
 tried with it. 
 
 In these the gas used is generated by adding diluted sul- 
 phuric acid to artificial ferrous sulphide. The ferrous sul- 
 
SULPHUR. 151 
 
 phide is usually manufactured by heating a mixture of roll 
 brimstone and iron filings in a sand crucible. In producing 
 the gas the chemical change is represented by the follow- 
 ing equation: 
 
 FeS -j- 
 
 H 2 S0 4 
 
 H 2 S 
 
 -f FeSO 4 
 
 One molecule of 
 
 One molecule of 
 
 One molecule of 
 
 One molecule of 
 
 Ferrous sulphide, 
 
 Sulphuric acid, 
 
 Sulphuretted 
 hydrogen. 
 
 Ferrous sulphate, 
 
 88 
 
 98 
 
 34 
 
 152 
 
 parts by weight. 
 
 parts by weight. 
 
 parts by weight. 
 
 parts by weight. 
 
 186 186 
 
 For the purpose of the experiments here mentioned a 
 flask or bottle may be used to prepare the gas and convey 
 it into another bottle containing water. In the water the 
 sulphuretted hydrogen gas dissolves in such quantity that 
 the solution so afforded may be conveniently employed for 
 showing the properties of the gas itself. 
 
 The following interesting experiments may be performed 
 by use of this solution: 
 
 1. Dissolve in water a small quantity of plumbic acetate, 
 also called sugar of lead. Filter this solution if convenient. 
 To the clear liquid add some sulphuretted hydrogen water. 
 A black precipitate of plumbic sulphide (PbS) should imme- 
 dately appear. 
 
 2. Dissolve in hydrochloric acid a fragment of white 
 arsenic not bigger than a pin's head. To the solution freely 
 add sulphuretted hydrogen water. A beautiful lemon-yellow 
 precipitate, consisting of arsenious sulphide (As 2 S 3 ), should 
 result. 
 
 3. Dissolve in hydrochloric acid a minute quantity of tar- 
 tar-emetic. To the solution freely add sulphuretted hydro- 
 gen water. A beautiful orange-red and flaky precipitate of 
 antimonious sulphide (Sb 2 S 3 ) should appear. 
 
 4. Dissolve in water a minute fragment of cupric sulphate, 
 commonly called sulphate of copper or blue vitriol. To the 
 solution add some of the sulphuretted hydrogen water. 
 
152 CHEMISTRY. 
 
 This should instantly give rise to a black precipitate of 
 cupric sulphide (CuS). 
 
 5. Dissolve in water a small quantity of zinc sulphate. To 
 the solution freely add sulphuretted hydrogen water. There 
 should appear in this case a white precipitate consisting of 
 zinc sulphide (ZnS). 
 
 These few experiments show that sulphuretted hydrogen 
 is a convenient substance for bringing sulphur into union 
 with the metals, and, moreover, they sustain the statements 
 already presented, that many metals show strong affinity for 
 sulphur and marked tendencies to combine with it. For 
 these reasons sulphuretted hydrogen is much used in chem- 
 ical laboratories for distinguishing one metal from another.* 
 
 Sulphur Dioxide. 
 
 When sulphur burns in oxygen gas or in atmospheric air 
 it gives rise to a new gas of choking and offensive odor. 
 This is the same substance as that produced in the first 
 stages of the burning of a sulphur match. It is a substance 
 of considerable importance in the arts, first, because it is 
 always produced in one stage of the process used in the man- 
 ufacture of sulphuric acid. Now sulphuric acid (commonly 
 called oil of vitriol) is a commercial product of enormous 
 consumption. (See page 156.) Again, sulphur dioxide is 
 used, as such, to a considerable extent in the arts, the prin- 
 cipal uses being in the bleaching of straw and woolen goods. 
 Chlorine as a bleaching agent has already been discussed, 
 but it is used mainly for the bleaching of cotton and linen 
 goods; it has an unfavorable and injurious action upon straw 
 and woolen goods. 
 
 The way in which these latter are bleached by the use of 
 sulphur may be illustrated by a very simple experiment. 
 Place a few fragments of roll brimstone in a small crucible. 
 Heat the crucible carefully until the sulphur takes fire. 
 Then cover the burning sulphur with a glass lamp-chimney, 
 
 * See Appleton's Qualitative Analysis, published by Cowperthwait & Co., Philadel- 
 phia, p. 14. 
 
SULPHUR. 153 
 
 or any other suitable contrivance. In the top of the chim- 
 ney hang a moistened carnation pink or other red flower. 
 A few minutes' exposure to the gas results in a partial 
 bleaching of the flower. 
 
 On a commercial scale the sulphur bleaching process is 
 conducted in practically the same manner. For bleaching 
 woolen goods there is provided a small wooden house having 
 a brick floor with a small pit in the center. The goods are 
 hung up in this house. The pit is filled with sulphur which, 
 when all is ready, is set on fire by throwing a piece of red-hot 
 iron upon it. Now the doors and windows of the house are 
 closed. Of course the sulphur burns into sulphur dioxide. 
 The operation is allowed to proceed without any further 
 attention during one night. The gas distributes itself 
 throughout the goods and bleaches them. The next morn- 
 ing the doors and windows are opened, and, when the fresh 
 air has driven the sulphur dioxide from the chamber, the 
 goods are found to be bleached. Every one knows, how- 
 ever, that this bleaching has not the permanence that chlorine 
 bleaching has. Thus white flannels very soon return to their 
 original yellowish shade. 
 
 Sulphur dioxide is placed by the chemist in the class of 
 acid anhydrides. This term is intended to carry the mean- 
 ing that substances belonging to this class combine with 
 water to form acids. In accordance with this form of ex- 
 pression, sulphur dioxide is also called sulphurous anhydride. 
 Plainly this means that sulphur dioxide with water will form 
 an acid. Such seems to be indeed the case, for water has 
 the power of dissolving large quantities of sulphur dioxide, 
 and when it does so the water acquires the characteristics of 
 an acid. In fact it is then called sulphurous acid. 
 
 SO 2 + H 2 O = H 2 SO 3 
 
 One molecule of One molecule of One molecule of 
 
 Sulphur dioxide, Water, Sulphurous acid, 
 
 64 18 82 
 
 parts by weight. parts by weight. part* by weight. 
 
 82 
 
154 CHEMISTRY. 
 
 One special characteristic which justifies the name sul- 
 phurous acid is the fact that the solution so produced has 
 the power of producing a series of salts as the other acids 
 do. In this case the salts have the general name sulphites. 
 
 READING REFERENCES. 
 Sulphur from Popocatapetl. Science, vi. p. 390. 
 Sulphur Industry in Sicily. 
 
 Barbaglia. A. Chem. News, xxxiv. 245 ; xxxv, 3, 28. 
 Vincent, C. Am. Chem. Journal, vi, 63. 
 Sulphur, Extraction of. 
 
 Sestini, F. Jour. Chem. Soc. of London, xxviii, 335. 
 
SULPHUR TRIOXIDE. 155 
 
 XVIII. 
 
 SULPHUR TRIOXIDE. 
 
 lULPHUR trioxide does not exist by itself in 
 nature. Moreover, it is but little known even as 
 an artificial product. It is not an article of ordi- 
 nary sale, though it is occasionally made by the 
 chemist. Yet it is a constituent part of one of the most im- 
 portant compounds known to modern industry. That com- 
 pound is sulphuric acid. 
 
 Sulphur trioxide is a white solid, but it cannot easily be 
 kept so. This is because it has very strong affinity for moist- 
 ure. In fact it readily absorbs that water vapor which is 
 distributed through the atmosphere even in dry weather, 
 and when the ordinary observer would suppose that the air 
 contained no moisture at all. When it absorbs moisture it 
 chemically combines with it, forming sulphuric acid. 
 
 The chemical change is represented by the following 
 equation : 
 
 H 2 S0 4 
 
 One molecule of 
 
 Sulphuric acid, 
 98 
 
 parts by weight. 
 
 98 
 
 On account of this reaction sulphur trioxide is often spoken 
 of as sulphuric anhydride, the term anhydride (or acid anhy- 
 dride, more properly) being intended to suggest that the sub- 
 stance so named is derived from an acid by the removal of 
 water from the latter. Thus sulphuric acid minus water 
 produces sulphuric anhydride. And this harmonizes with 
 what has before been declared; namely, that sulphuric anhy- 
 dride or sulphur trioxide plus water produces sulphuric 
 acid. 
 
 SOa + 
 
 H 2 
 
 One molecule of 
 
 One molecule of 
 
 Sulphur trioxide, 
 
 Water, 
 
 80 
 
 18 
 
 parts by weight. 
 
 parts by weight. 
 
 98 
 
 
156 CHEMISTRY. 
 
 Sulphuric Acid. 
 
 This substance is known to commerce chiefly under the 
 name of oil of vitriol. It is an oily liquid nearly twice as 
 heavy as water. It has very powerful chemical action upon 
 most substances with which it comes in contact. Moreover, 
 its market price is very low that is, between one and two 
 cents a pound at wholesale. To these two facts last men- 
 tioned that is, the marked chemical power and the low 
 price is referable the enormous demand for the substance. 
 To be sure, increase of demand and fall in price have a 
 reciprocal action. Even a slight cheapening of a substance 
 widens considerably the range of its possible uses, and 
 increases the amount consumed. Again, increase of demand 
 and consumption lead manufacturers to increase their pro- 
 duction, a circumstance which is generally followed by lower 
 price. The manufacture of sulphuric acid exemplifies these 
 well-known principles of political economy. The manufact- 
 ure of this substance has risen within the last hundred years 
 from almost nothing to a present annual production of about 
 nine hundred thousand tons in Great Britain alone. The 
 price meanwhile has fallen to about one thirtieth of what it 
 was in the middle of the last century. At the present time 
 the price of oil of vitriol seems to be steadily decreasing, 
 while the amount produced is steadily increasing in England, 
 France, Germany and the United States indeed in all 
 countries pervaded by active industrial enterprise. It will 
 be generally admitted, as M. Dumas has said, that the 
 amount of sulphuric acid consumed affords a very precise 
 measure of the advancement in industrial arts of a given 
 country or of a historical epocli. 
 
 Uses of Oil of Vitriol. 
 
 It would be difficult to enumerate the many industries that 
 demand the use of sulphuric acid. It must likewise be 
 admitted that there are but few manufacturing operations 
 which do not directly or indirectly involve its employment. 
 
SULPHUR TRIOXIDE. 157 
 
 The industries that stand in the front rank as direct con- 
 sumers of this acid are those that involve the following 
 processes; namely, the bleaching of cotton goods ; the 
 removal of scale from iron in its various forms, such as cast- 
 ings, wire, etc.; the changing of corn starch into the variety 
 of sugar commonly called glucose; the refining of bullion of 
 gold and silver; the refining of petroleum oil; last, but not 
 least, the manufacture of chemical fertilizers for agricultural 
 use. Less directly, but still in enormous quantities, it is used 
 in the manufacture of soda-ash and bleaching powder, already 
 referred to as having reached an incredible consumption; in 
 the manufacture of alum; in the manufacture of both of the 
 great acids of commerce, hydrochloric acid and nitric acid, 
 which must be said to come next to sulphuric acid in useful- 
 ness; and finally, in almost all the distinctly chemical indus- 
 tries. 
 
 Manufacture of Sulphuric Acid. 
 
 Notwithstanding the extremely low price of oil of vitriol 
 and the immense quantity of it manufactured its production 
 implies a series of processes far more complicated than those 
 involved in the preparation of any other well-known acid. 
 Moreover, although the various intricate details of its prep- 
 aration are matters of thorough experimental knowledge to 
 the producer, there are several steps which are not yet 
 clearly comprehended even by the most eminent chemists of 
 the age. 
 
 The process of manufacture, as at present conducted, is 
 properly described as a continuous one. By this it is meant 
 that the raw materials are steadily introduced at one end of 
 the apparatus used, and the finished product is steadily drawn 
 out at the other, the'process meanwhile going on without inter- 
 ruption night and day for years. In order to a better com- 
 prehension of the process it is here described in four stages. 
 
 In the first stage, sulphur is burned in a current of air. The 
 material employ e*d is either partly refined Sicily sulphur, or, 
 what is largely used at the present day, some mineral com- 
 
158 
 
 CHEMISTRY. 
 
 pound of sulphur, like the iron and copper pyrites. In either 
 case sulphur dioxide (SO.,) is formed. This is the well-known 
 choking gas given out by a burning sulphur match. As pro- 
 duced on a large scale the gas passes into a series of enormous 
 leaden chambers. These are in fact rectangular rooms, often 
 as large as one hundred and fifty feet long, twenty feet wide 
 and fifteen feet high. Generally at least three chambers are 
 in a series, connected by leaden pipes. Sulphur dioxide gas 
 flows in a steady stream into the series of chambers and 
 
 FIG. 40. Section of building fitted for manufacture of sulphuric acid : f. furnacp 
 where sulphur is burned and oxides of nitrogen are liberated ; /f, boiler from which 
 steam is supplied to the leaden chamber, A. 
 
 toward the high chimney of the works, whose draft produces 
 the advance of gases through the whole apparatus. 
 
 The second stage is the most complicated one. It is the 
 oxidizing of the sulphur dioxide (SO 2 ) into sulphur trioxide 
 (SO 3 ). This is indeed accomplished by means of the oxygen 
 of the air. But this oxygen is not capable of directly chang- 
 ing SO 2 into SO 3 . Certain gaseous oxides of nitrogen are 
 forced into the chamber at this stage ; and these have the 
 remarkable power on the one hand of taking oxygen to 
 themselves from the air, and on the other of imparting this 
 oxygen to the compound SO 2 in such a way as to change it 
 into the compound SO 3 . Of course the air is impoverished 
 
S0 3 + 
 
 H 2 
 
 One molecule of 
 
 One molecule of 
 
 Sulphur trioxide, 
 
 Water, 
 
 80 
 
 18 
 
 parts by weight. 
 
 parts by weight. 
 
 v 
 
 j 
 
 SULPHUR TRIOXIDE. 159 
 
 by the operation, a fact which necessitates a fresh supply of 
 it through the entire series of chambers. 
 
 The third stage is one whose principle has already been 
 explained. At various parts of the chamber jets of steam 
 are blown in. While these aid mechanically in the progress 
 of the gases through the entire series their main purpose is 
 to furnish water which shall combine with sulphuric anhy- 
 dride to produce sulphuric acid. 
 
 Although the equation representing this chemical change 
 has been given before it may not be improper to repeat it here: 
 
 H 2 S0 4 
 
 One molecule of 
 
 Sulphuric acid, 
 
 98 
 
 parts by weight. 
 
 98 98 
 
 The effect of the steam is to give rise to a steady rain of 
 sulphuric acid in the chambers. Of course this liquid collects 
 at the bottom. Thence it is drawn off to the evaporators for 
 treatment in a fourth stage. 
 
 It is plain that up to this point the series of chemical reac- 
 tions takes place in what we may characterize as a vast but 
 irregular tube, open at both ends. This tube is enlarged 
 here and there into great pockets which constitute the cham- 
 bers. It is bent into a form appropriate to the conditions of 
 the business. It is entered here and there by pipes for in- 
 troducing the agents whose proper interaction gives rise to 
 the product sought. It is also tapped for the purpose of 
 drawing off the acid generated. This open tube has its final 
 exit into the atmosphere through the tall chimney with which 
 it is connected. It has its first connection with the atmos- 
 phere at the open throat, which swallows at once the vast 
 volumes of sulphurous gas from the sulphur burned, and at 
 the same time levies upon the air to contribute its oxygen 
 to produce the substance which is the final purpose of the 
 whole industry. 
 
 The process thus far described cannot be made to produce. 
 
160 
 
 CHEMISTRY. 
 
 acid of the strength demanded by commerce. In the fourth 
 stage, then, the acid from the chambers is boiled, with a view 
 of expelling some of the water in it, and thus of producing 
 a more concentrated product. This evaporation is itself no 
 inconsiderable portion of the business. It is conducted first 
 in shallow tanks of lead, and finally in costly stills of platinum. 
 When at length the acid in the platinum stills has attained 
 the proper degree of concentration it is drawn out by means 
 of a siphon tube, and through a cooling tank of cold water 
 into the glass flasks called carboys, in which it makes its ap- 
 pearance in commerce. 
 
 FIG. 41. Section of apparatus used for concentrating sulphuric acid. A, A, leaden 
 pan.s in which the first evaporation is conducted; B, platinum retort in which the 
 concentrating is finished. 
 
 Of course the account thus given is but a general sketch of 
 this great industry. Associated with the apparatus and the 
 processes here briefly described there are employed in actual 
 working a multitude of other devices and operations. Indeed, 
 it might be anticipated that the successful conduct of a bus- 
 iness of such magnitude and complexity would draw upon 
 the inventive resources of some of the best minds that have 
 been brought to bear upon chemical industries. 
 
 READING REFERENCES. 
 Sulphuric Acid. 
 
 Affleck, J. Chem. News, xxxvii, 167, 192, 207. 
 
 Hasenclever, R. Chem. News, xxxv. 48, 67. 88, 118, 183, 189, 214, 227. 
 
BORON, 161 
 
 XIX. 
 
 BORON. 
 
 |HE white substance called borax has long been 
 known to exist as a solid deposit in the earth of 
 many parts of the ancient East. But its uses have 
 increased a thousandfold as the result of the 
 modern discovery of new and far more abundant sources of 
 it. Thus in the manufacture of porcelain and in other of 
 the industrial arts, and as a remedial agency in medicine, 
 borax has now come to be an important and truly useful sub- 
 stance to mankind. 
 
 The knowledge of its composition is referable to a very 
 recent date ; it is only in the present century that its char- 
 acter as a true chemical salt was fully made out. Borax is 
 now recognized as sodic borate, which usually exists in a 
 form holding ten molecules of water of crystallization ; ac- 
 cordingly the chemical formula is Na 2 B 4 O 7 10 H 2 O. From 
 this it appears that, in addition to the well-known substances 
 sodium and oxygen, borax contains a special and peculiar 
 element called boron a name evidently derived from borax. 
 Again, being a salt, the substance must be viewed as contain- 
 ing an acid or, more properly speaking, the representative 
 of an acid. That this is indeed the fact may be readily proved. 
 If borax is dissolved in water in such a way as to form a con- 
 centrated solution, then, upon addition of hydrochloric acid, 
 a solid substance separates in pearly flakes ; this upon subse- 
 quent examination is found to be an acid. This solid acid 
 has received the name boric acid, and it may be represented 
 by the formula H 3 BO 3 . 
 
 Sources of Borax in Nature. 
 
 For a long time the only known source of borax was the 
 natural crusts of this substance found principally in the 
 11 
 

164 CHEMISTRY. 
 
 ground in certain parts of Asia. At the present day, how- 
 ever, borax is obtained from Borax Lake, in California, in 
 very large quantities. In fact the commercial needs of the 
 United States for this substance are readily supplied from 
 borax found within its own borders. The most interesting 
 and important step in connection with the preparation of borax 
 dates back to about the year 1776, when the fact was made 
 public that certain lagoons in Tuscany contained boric acid 
 in their water. It was not until about the year 1828, how- 
 ever, that the manufacture of boric acid from this source 
 was successful upon a large scale. In some of the Tuscan 
 valleys there are volcanic crevices in the earth, called suffioni. 
 From them steam escapes charged with certain compounds of 
 boron. When this steam is brought in contact with water 
 boric acid is liberated in the water. The method of secur- 
 ing the acid is as follows : a ring of masonry is built in a 
 suitable place and so as to include several suffioni. Some- 
 times new suffioni are artificially bored within this ring. 
 Into the basin so produced water from some convenient spring 
 is conducted. The steam from the suffioni passing into the 
 water produces boric acid there. When the water is suffi- 
 ciently charged it is made to flow as a gentle cascade over 
 a long series of shallow pans. The liquid readily evaporates 
 from these pans, for under them also steam from suffioni is 
 turned. It is indeed this last mentioned step in the manu- 
 facture that became the turning point which has led to its 
 successful prosecution. The great cost of fuel for artificially 
 evaporating the acid liquors rendered unprofitable the earlier 
 attempts to utilize this source of boric acid. A French gentle- 
 man, M. Larderel, suggested the use of steam from suffioni 
 for the evaporation of the liquids produced, and the process 
 was so successful that he quickly derived a colossal fortune 
 from its employment. At the same time he enriched the 
 territory that was previously not only desert and unproduc- 
 tive, but also was looked upon by the inhabitants with super- 
 stitious dread, and as little better than the gate of the infernal 
 regions. As a result of these inventions a barren and mi- 
 
frequented territory has been changed to a seat of thriving 
 and beneficial industry. Finally, it is interesting to note 
 that for his services in developing the boric acid industry 
 M. Larderel was created Count of Monte-Cerboli by the 
 Grand Duke of Tuscany. 
 
 READING REFERENCES. 
 
 Boric Acid, Manufacture of, etc. 
 
 Payen. Annales de Chimie et de Physique. 3 Sur. i, 247 ; ii, 322. 
 Dieulafait, L. toe. sit. 5 Ser. xii, 318; xxv, 145. 
 
 Borax Lagoons of Tuscany. 
 
 Harper's Magazine, i, 397. 
 
 Borax of California, history of. 
 
 Robottom, Arthur. Chem. News, liv, 244. 
 
106 
 
 XX. 
 
 NITROGEN. 
 
 lITROGEN is an important constituent of our atmos- 
 pheric air, of which it makes up about eighty per 
 cent. ; the other twenty per cent, being oxygen. 
 In the air the nitrogen is found in the free or un- 
 combined state, and we may reasonably suppose that it exists 
 here to fulfill some important offices. Unquestionably one 
 of these is that of diluting the oxygen, the energetic constit- 
 uent of air, and lessening its activities for nitrogen itself 
 is extremely inert. From the part it performs in the atmos- 
 phere nitrogen derives a considerable portion of the interest 
 with which it is invested. 
 
 Discovery of Nitrogen. 
 
 Perhaps the first clearly defined recognition of nitrogen as 
 a constituent of the air is referable to the genius of a wonder- 
 ful man, who, in obscurity and with very simple apparatus, 
 obtained an insight into the constitution of substances which 
 has rarely been surpassed. Reference is here made to the 
 Swedish, or rather Prussian, chemist Scheele, some of whose 
 discoveries have been briefly adverted to in earlier chapters. 
 It has already been stated that the distinct notion of a gas 
 dates but little more than a hundred years back ; and this 
 statement is intended to call to mind that brilliant period in 
 the history of chemistry when, among others, Black in Scot- 
 land, Cavendish and Priestley in England, Lavoisier and his 
 worthy associates in France, and, finally, the sagacious Scheele 
 in Sweden, were engaged in a generous rivalry in chemical 
 studies, which made the close of the eighteenth century a 
 period in the history of chemistry that will not be forgotten 
 so long as the science itself shall endure. At this time un- 
 
NITROGEN. 167 
 
 stinted effort was devoted, with ingenious but imperfect 
 appliances, to the study of gases. Of course the atmospheric 
 air, as the gas most vast in quantity, most accessible for ex- 
 periment, most important in its relation to the economy of 
 living beings, received its full share of attention. It was at 
 this period that Dr. Rutherford, a professor in the University 
 of Edinburgh, demonstrated that after living animals have 
 breathed in a confined bulk or volume of air there remains 
 an inert and peculiar gas behind. And Priestley showed 
 that after the burning of charcoal in a confined volume of air 
 there remains a gaseous material equal to about four fifths 
 of the amount of original air used. But it was Scheele who 
 first clearly pointed out that the air contains a second distinct 
 constituent that fails to support combustion and animal res- 
 piration. And Lavoisier first proved this constituent to be an 
 elementary substance, and he gave to it the name azote, 
 which it still retains in the French nomenclature of chem- 
 istry, and which is also used (in composition) in many En- 
 glish chemical terms to express the nitrogenous constituent. 
 It is not forgotten that a critical examination of the history 
 of human knowledge respecting the atmosphere reveals the 
 fact that a wonderfully clear, even though incomplete, ac- 
 count of the functions of the active constituent of the air was 
 printed as early as the year 1669, by an English physician 
 named John Mayow.* This affords another illustration of 
 the fact, recognized by all students of history, that often, in 
 the progress of knowledge, before the clear and full dawn 
 there seems to be a twilight; at such a time, and before the 
 darkness has been fully dispelled, there have been found here 
 and there men gifted with supernatural mental vision who 
 have been able to read the laws of nature long before acknowl- 
 edged philosophers, even, had found light sufficient. And so 
 the truths learned by Mayow, though clearly stated by him, 
 failed of recognition until they were rediscovered a hundred 
 years later. (See p. 113.) 
 
 *KOPP, HERMANN : Qeschichte der Chemie. Dritter Thell. s. 193. 
 
168 
 
 CHEMISTRY. 
 
 Preparation of Nitrogen. 
 
 Nitrogen is usually prepared from the air by the with- 
 drawal of oxygen from it. This withdrawal is effected by 
 some substance which has a strong affinity for oxygen. 
 
 One method frequently resorted to is to burn phosphorus 
 in air. Phosphorus is placed in a little crucible of porcelain 
 and then floated upon a cork on the surface of water in a 
 pneumatic trough. A bell-glass of air is now inverted over 
 
 FIG. 44 Preparation of nitrogen from air, by absorbing the oxygen by burning 
 phosphorus. 
 
 the phosphorus, after the latter has been set on fire. The 
 phosphorus burns at the expense of the oxygen in the bell- 
 glass. Thus the oxygen is little by little withdrawn, and as 
 a result the nitrogen is left. Another method for preparing 
 nitrogen is based upon the same general principle. It is the 
 following : pass a current of dry air through a tube contain- 
 ing copper turnings heated to dull redness in a furnace. 
 Under these circumstances the copper absorbs oxygen from 
 the air, and leaves the nitrogen, which passes on to a receiver 
 prepared for it. 
 
NITROGEN. 1G9 
 
 Properties of Nitrogen. 
 
 Nitrogen prepared by these methods, or by any others, pos- 
 sesses the following characteristics : 
 
 It is a gas that is colorless, odorless and tasteless. It is 
 not necessary to make any scientific demonstration of these 
 facts, because with every breath of air drawn into the lungs 
 of a human being a large quantity of nitrogen is inhaled, 
 and it is easily perceived to be without odor or taste, while 
 a glance of the eye into the atmosphere shows that, in moderate 
 quantities, at least, it is free from color. Up to a period dnt- 
 ing but a few years back nitrogen was spoken of as one of 
 the permanent gases ; and this word permanent was intended 
 to convey the idea that it is not condensable to the liquid 
 form. It is true that it was surmised that for every gas there 
 must be a point of very low temperature and very great 
 pressure at which the gas would assume the liquid form. 
 Yet nitrogen, and two or three others, resisted all such at- 
 tempts to liquefy them until toward the close of the year 1878. 
 Since that time successful effort has been made to bring to 
 a higher degree of perfection the appliances used for sub- 
 jecting gases at once to intense cold and enormous pressure. 
 With these it is believed that small amounts of nitrogen have 
 been liquefied. And it may even be said that there is now 
 no permanent gas known, but that all gaseous substances 
 may in fact be liquefied.* 
 
 As a simple and uncombined substance nitrogen is char- 
 acterized by extreme inactivity. It does not burn ; it does 
 not support combustion ; it cannot be made to enter into 
 chemical union with other substances, except by specially 
 devised and circuitous processes. 
 
 While on the one hand inertness is the mnrked character- 
 istic of the nitrogen, on the other hand this element is a 
 constituent of a very large number of compounds. Moreover, 
 these compounds are themselves often characterized by a 
 high degree of activity. Of the last two declarations the 
 
 * SCHIJTZENBERGER, PAUL : Traiti de Chimie Generate, Paris, 1880, i, 30. 
 
170 CHEMISTRY. 
 
 first one seems to be inconsistent with the properties of nitro- 
 gen in its elemental form. The second one seems inconsist- 
 ent, but less so when it is carefully considered. Thus the 
 activity of the compounds of nitrogen is to a certain extent 
 referable to their instability. The meaning of instability, 
 as used here, is that the compounds are easily decomposed ; 
 and this is because the inert nitrogen readily lets go its hold 
 upon the other elements. Whence it appears that the ac- 
 tivity of the compounds, is really referable to the energetic 
 action of the element or elements now loosed from the nitro- 
 gen, rather than to the nitrogen itself. 
 
 In nature nitrogen is found as a constituent in some very 
 important compounds. Thus it seems to be an essential 
 element of some of the principal animal matters, such as mus- 
 cular fibre and the material of the brain. Again, it is a con- 
 stituent of ammonia gas and also of a multitude of compounds 
 derived from it. Now these compounds are members of a 
 group of substances which serve as most valuable kinds of 
 food for living plants. So it may be said that both living 
 animals and plants seem to be in a peculiar way dependent 
 upon nitrogen or nitrogenous matters. 
 
 Compounds of Nitrogen and Hydrogen. 
 
 Properly speaking, only two compounds of nitrogen and 
 hydrogen are known : 
 
 Diamidogen (Hydrazine.) 2XH 2 (or N 2 H 4 ). 
 
 Ammonia Gas. NH 3 . 
 
 A third compound called ammonium (NH 4 ), and viewed 
 as a hypothetical metal, is often referred to. Since, however, 
 this substance is at present known only in combination with 
 other elements it must be considered as having a theoretical 
 rather than a real existence. 
 
 Hydrazine. 
 
 This substance is a colorless gas which, when mixed with 
 much air, has but little odor; when concentrated, however, 
 
NITROGEN. 171 
 
 it has a very irritating influence upon the mucous membranes 
 of the nose and throat. It is of chief interest to chemists be- 
 cause of its history. From certain compounds containing ni- 
 trogen, hydrogen, and other substances, it has long been recog- 
 nized that the group of atoms represented by the expression 
 NH 2 has a kind of integrity which suggested the possibility of 
 its separate existence. It was not practicable, however, to 
 produce it as a separate compound until very recently. Theo- 
 dor Curtius has within a short time announced that he has 
 prepared the substance, and he has described his method. 
 
 Ammonia Gas. 
 
 Under favorable circumstances nitrogen and hydrogen 
 combine to form the stable, interesting and important com' 
 pound called ammonia gas, and having the formula NH 3 . 
 
 While the gas may be produced by the direct union of the 
 constituents that is, w r hen a mixture of nitrogen gas with 
 hydrogen gas has an electric discharge slowly passed through 
 it this is not a common mode of procedure. Ammonia gas 
 is oftener produced by a natural or artificial decomposition 
 of certain substances that contain nitrogen and hydrogen 
 among their constituents. As it has already been stated that 
 many animal matters contain nitrogen and hydrogen, it fol- 
 lows that animal matters when decomposed afford ammonia 
 gas ; and so they do, in fact, whether the decomposition is 
 in the course of their natural decay, or whether it is con- 
 ducted artificially, as, for example, when animal matters are 
 heated in closed vessels to the point of decomposition. In- 
 deed ammonia gas and its important commercial compounds 
 were formerly produced in this last-mentioned manner. 
 
 Ammonia gas or some compound of it is also formed, 
 as may be readily imagined from what has already been said, 
 from decomposition of vegetable matters containing nitrogen. 
 It is a fact that at the present day the principal supplies of 
 ammonia gas and its compounds for the uses of commerce 
 and the arts come from such a source that is, from the arti* 
 
172 CHEMISTRY. 
 
 ficial decomposition of bituminous coal. It is true that in 
 the ordinary sense coal is not vegetable matter. But careful 
 examination of it shows that it is very directly derived from 
 the vegetation of ancient forests. The vegetable matter has 
 been packed away in the earth and has been subjected to 
 water, heat and pressure under such conditions that these 
 agencies have changed it to the form in which we find it. 
 Now the coal-gas industry of the present day is so conducted 
 as to decompose coal and collect many of the products of its 
 decomposition. One of these products is ammonia gas. To 
 the decomposition of coal, therefore, the business world at 
 present looks for its supply of ammonia gas and the many 
 compounds derived from it. 
 
 The name ammonia gas indicates that it ordinarily exists 
 in the aeriform condition. It has a very pungent odor, well- 
 known as that evolved from smelling-salts. It dissolves in 
 water with very great facility and in very large quantities. 
 It has a strong tendency to combine with acids. This last 
 fact may be easily illustrated by simple experiments within 
 the reach of almost any one. 
 
 Experiment with Ammonia. 
 
 Provide two wine-glasses, or two shallow vessels of any 
 sort. Into one of them pour the liquid known as spirits of 
 hartshorn, and called by the chemist ammonic hydrate. Into 
 the other pour some concentrated hydrochloric acid. Abun- 
 dant white clouds will quickly form above the vessels and 
 between them. These clouds are composed of minute par- 
 ticles of a solid, called by the chemist ammonic chloride and 
 expressed by the formula NH 4 C1. The reason for their for- 
 mation is this : from the spirits of hartshorn escapes ammo- 
 nia gas (NH 3 ); from the acid there constantly escapes 
 hydrochloric acid gas (HC1 ) ; the two gases meeting in the 
 atmosphere combine with energy and form the smoky prod- 
 uct referred to. 
 
 The chemical change is represented by the following 
 equation : 
 
NITROGEN. 173 
 
 NH 3 H 
 
 HC1 
 
 NH 4 C1 
 
 One molecule of 
 
 One molecule of 
 
 One molecule of 
 
 Ammonia-gas, 
 
 Hydrochloric acid, 
 
 Ammonic chloride, 
 
 17 
 
 36 
 
 53 
 
 parts by weight. 
 
 parts by weight. 
 
 parts by weight. 
 
 The ammonic chloride thus produced is an article of com- 
 merce, well-known under the name sal ammoniac. As has 
 been said, it is a solid, and it belongs to the class of sub- 
 stances designated by chemists as salts. In fact, one of the 
 most striking characteristics of ammonia gas is its power to 
 produce salts by union with acids. Here is a list of three 
 well-known salts of this sort : 
 
 With Hydrochloric acid, HC1 it produces Ammonic chloride, NII 4 C1. 
 " Nitric acid, HN0 3 it produces Ammonic nitrate, NH 4 N0 3 . 
 
 " Sulphuric acid, H 2 S0 4 it produces Ammonic sulphate, (NH i) 2 S0 4 . 
 
 Commercial use of Ammonia Gas. 
 
 One of the chief uses of the ammonia afforded by the illu- 
 minating gas industry is in machines for producing ice arti- 
 ficially. 
 
 The general principle of these machines may be stated as 
 follows : By powerful pumps they compress ammonia gas to 
 the liquid form and the heat, called latent heat, of the gas is 
 now freely evolved, and it is carried away by an abundant 
 stream of flowing water. The liquid ammonia is next trans- 
 ferred to the jacketed space surrounding the relatively small 
 amount of water which is to be frozen. 
 
 By the working of the ice machines this liquid ammonia 
 vaporizes ; it now begins to absorb heat in amount equiva- 
 lent to the latent heat it previously evolved. The machine 
 is so adjusted that the ammonia shall absorb this heat from 
 the small amount of water to be frozen. This water being 
 deprived of heat is so much reduced in temperature that it 
 reaches the freezing point, and thereupon solidifies. 
 
174 CHEMISTRY. 
 
 Compounds of Nitrogen and Oxygen. 
 
 Nitrogen and oxygen ordinarily manifest scarcely any af- 
 finity for each other. There are conditions, however, under 
 which they unite ; and, moreover, they unite in different pro- 
 portions so as to form at least five different compounds. 
 These may be presented in the form of the following striking 
 series : 
 
 Nitrogen protoxide (called laughing-gas,) N 2 0. 
 
 Nitrogen dioxide, N 2 2 (or NO). 
 
 Nitrogen trioxide or nitrous anhydride, N 2 3 . 
 
 Nitrogen tetroxide (brown fumes,) N 2 4 (or N0 2 ). 
 
 Nitrogen pentoxide or nitric anhydride, N 2 5 . 
 
 Of these compounds unquestionably the most important 
 is nitric anhydride and this not on account of itself, for it 
 is very rarely produced either in the arts or in the investi- 
 gator's laboratory. Its importance is referable to the fact 
 that, added to water, it produces nitric acid. 
 
 This chemical change is represented by the following 
 equation : 
 
 N 2 O 5 + H 2 O 2HNO :i 
 
 One molecule of One molecule of Two molecules of 
 
 Nitric anhydride, Water, Nitric acid, 
 
 108 18 126 
 
 parts by weight. parts by weight. parts by weight. 
 
 126 126 
 
 Nitric Acid. 
 
 This acid has been referred to in another place as one of 
 three principal acids of commerce. Certain of its most strik- 
 ing properties may be displayed in an easy interesting man- 
 ner by any one. For this purpose the following experi- 
 ments are suggested : 
 
 First experiment. Nitric acid turns quill yellow. 
 
 Place a few fragments of white quill in a test-tube. Add 
 a few drops of nitric acid and then some water. Now warm 
 the mixture. The quill will be found to acquire a yellow 
 
NITROGEN. 175 
 
 color. Fill the tube with cold water in order both to dilute 
 the acid and to cool it. Pour away the liquid and wash the 
 quill in water. The yellow color will be found to be perma- 
 nent. Many other animal matters are turned to a permanent 
 yellow color by nitric acid. 
 
 Second experiment. Nitric acid attacks copper with vio- 
 lence. There is liberated by the process a gas called nitrogen 
 dioxide (N 2 O 2 ), which is colorless but which becomes brown 
 upon exposure to the atmospheric air. The chemical change 
 gives rise to a solution sometimes green and sometimes blue, 
 according to circumstances. 
 
 Place in a test-tube a small piece of metallic copper in the 
 form of either wire or foil. Add some nitric acid to the cop- 
 per. Then warm it gently until the copper disappears. The 
 brown fumes will be recognized. The colored solution of 
 cupric nitrate, Cu (N0 3 ) 2 should also be noticed. 
 
 Third experiment. Nitric acid attacks zinc with great 
 violence. 
 
 Try another experiment quite similar to that just described, 
 only employ zinc in place of copper. Brown fumes are 
 evolved, and a colorless solution is produced containing zinc 
 nitrate, Zn (NO 3 ) 2 . 
 
 Fourth experiment. Nitric acid attacks iron with violence. 
 
 Try another experiment, quite similar to the second and 
 third, only employ iron instead of the other metals men- 
 tioned. The fine iron wire used by florists is suitable for 
 this purpose. The same brown fumes are evolved. A me- 
 tallic nitrate is also produced ; it is called ferric nitrate and 
 its formula is Fe 2 (NO 3 ) 6 . The solution is yellow, or but 
 slightly colored. 
 
 Fifth experiment. Nitric acid dissolves a nickel coin. 
 
 An experiment similar to those already detailed may be 
 tried upon a nickel coin ; but it is not necessary to entirely 
 dissolve the coin. After the acid has acted for a few 
 moments water may be poured into the tube so as to diluto 
 the acid and at the same time to cool it. Then the liquid 
 may be poured away and the coin withdrawn, In addition 
 
176 CHEMISTRY. 
 
 to the brown fumes evolved, the feature most noticeable is 
 the decided green color of the solution. This is referable, to 
 a considerable degree at any rate, to the nickel present. 
 Nickel imparts a green color to most of its solutions. 
 
 These experiments suggest that nitric acid has a marked 
 influence upon the metals. This is in fact one of its promi- 
 nent characteristics ; and it is largely used in the arts for the 
 purpose of dissolving metals. 
 
 READING REFERENCES. 
 
 Nitrogen, Chemistry of 
 
 Prescott, A. B. Jour. Araer. Chem. Soc. ix, 128. 
 
 Diaraide (hydrazine) 
 
 Curtius, T. Chem. News. lv, 288 ; Ainer. Chem. Jour, ix, 300. 
 
THE ATMOSPHERE. 177 
 
 THE ATMOSPHERE. 
 
 |HE atmosphere or the air of our globe is the vast 
 ocean of gaseous matter at the bottom of which 
 human beings, as well as other land animals, 
 dwell. While it is so thin that a vessel full of it 
 is spoken of in ordinary language as being empty, it yet pos- 
 sesses a reality which it often displays in a very serious man- 
 ner. Its presence is made gently evident to human beings 
 by the moderate resistance it offers to them when they are in 
 motion ; but when itself is in motion with the force of the 
 hurricane or tornado no solid matter can stand in its path. 
 Heavy railroad trains and massive buildings are hurled from 
 their positions and turned into miserable masses of wreck- 
 age, while even strongly rooted forests are swept out of place 
 by its vigorous breath. The terribly destructive power of 
 air at one moment and its mild and subtle efficiency at another 
 are very suggestive of the wonderful adjustment of the forces 
 residing in it. It is by the restrained action of these forces 
 that the atmospheric air is so admirably fitted to perform its 
 varied functions in connection with animal life. At the same 
 time it is so unobtrusive in its workings that its very existence 
 is at first scarcely noted. When at rest it peacefully wraps 
 the earth about as in a gossamer veil, but when in angry 
 agitation it scourges country and city alike as with a whip of 
 gigantic cables. 
 
 The height to which the atmospheric air extends above 
 the earth is not exactly known. But carefully-devised ex- 
 periments have shown that, going upward, its compactness or 
 density diminishes very rapidly. Indeed, calculations based 
 upon exact experiment show that at a height of forty miles, 
 or thereabouts, from the surface of the earth, the air is so 
 highly rarefied that practically it there comes to an end. In 
 12 
 
178 CHEMISTRY. 
 
 other words, at this height a given bulk of space contains no 
 more air than exists in the so-called vacuum produced by a 
 superior air-pump. 
 
 Weight of Air. 
 
 Notwithstanding the extreme tenuity of the gaseous 
 medium in which we live, it is capable of buoying up on its 
 wings a multitude of living beings of vast aggregate weight. 
 It is firm enough to support the millions of birds that sail in 
 it, and the myriad of millions of insects who yet more freely 
 navigate it in search of food and warmth, and in answer to 
 the various needs of their existence. 
 
 One of the most striking evidences of the fact that air is 
 indeed a material substance is very easily discovered by 
 showing that it possesses weight. Thus, suppose a properly 
 constructed glass globe is almost entirely emptied of air by 
 the action of an efficient air-pump. Suppose then that the 
 globe is weighed. Next if it be connected with a bell-glass 
 containing ordinary atmospheric air over a pneumatic trough, 
 it may be readily seen that the air leaves the bell-glass in 
 order to pass into the globe. If this globe is now weighed 
 again it is found to manifest a decided increase of weight 
 This increase is due to the air it has received. By such 
 means it may be easily show r n that a cubic yard of air weighs 
 not far from tw r o pounds. 
 
 Composition of Air. 
 
 The principal constituents of air are the two gases, oxygen 
 and nitrogen ; and of these the oxygen makes up about one 
 fifth and the nitrogen about four fifths of the whole. In ad- 
 
 3 
 
 dition to these principal substances, however, certain others 
 are always present, of which may be specified vapor of water, 
 carbon dioxide and ammonia gas ; while more minute quan- 
 tities of a vast multitude of other gaseous substances find a 
 reservoir in the air. It is an unquestioned fact that the 
 atmosphere is likewise charged most of the time with still 
 more minute quantities of solid dust materials of various kinds. 
 
THE ATMOSPHERE. 179 
 
 An example is found in the common salt, blown up into the 
 atmosphere from the ruffled surface of the oceans. Now 
 the oceans are spread over fully three fourths of the earth's 
 surface, and the winds, blowing upon the crested waves, not 
 only diffuse the salt over the oceans themselves but also carry 
 it far inland ; accordingly spectrum analysis reveals the pres- 
 ence of salt in almost all atmospheric air. 
 
 Just as the rivers of water flow to the ocean and bear 
 along to it debris of every kind pulverized rock and earthy 
 materials and other washings from the soil, leaves of forests, 
 impure products of civilization thrown in from houses and 
 manufacturing establishments and all these materials make 
 their relatively minute contributions to the impurities in the 
 great ocean itself, so it is with the atmospheric ocean. 
 Thousands of millions of living animals pour out, with every 
 breath from the lungs, materials exhaled from their bodies. 
 And so wherever fuel is burned, or wherever manufacturing 
 establishments liberate gases or vapors, or even finely pul- 
 verized solids, these are cast forth from the mouths of reek- 
 ing chimneys ; and they all flow into the great aerial sea. 
 So then it is no unexpected circumstance that the air should 
 be a reservoir in which, in minute quantity, is likely to exist 
 every gaseous substance produced. 
 
 Offices of the Several Constituents of the Air. 
 
 The oxygen of the air is its most active constituent. This 
 is the substance that has already been described as essential 
 for all ordinary combustion and all animal respiration. By 
 a great variety of characteristics it is well fitted for these 
 important offices. 
 
 The chief duty of the nitrogen appears to be to dilute the 
 oxygen and moderate the excessive activities that would be 
 manifested if the atmosphere consisted entirely of the active 
 gas. Since iron and other metals burn in pure oxygen, it is 
 plain that in an atmosphere of oxygen containing no mod- 
 erating gas like nitrogen a fire once kindled in a stove 
 
180 CHEMISTRY. 
 
 would not confine itself to its proper fuel, but would soon 
 spread to the metal of the stove itself, and so initiate con- 
 flagrations that could hardly be restrained. 
 
 The moisture in the air adds a number of wonderful and 
 serviceable characteristics to it. Thus it helps to retain the 
 heat received from the sun and so materially contributes to 
 the sustenance of animal and vegetable life. The heat of 
 the sun penetrates our atmospheric coverlet with great readi- 
 ness and this heat is received by the surface of the earth and 
 thence is imparted to the layer of air immediately upon it. 
 Now the moisture contained in the atmosphere and in prin- 
 cipal quantity in the portions of air closest to the earth is 
 one of the chief agencies that prevent the immediate escape 
 of that heat that the solid earth has secured from the sun's 
 rays. And it is in the warm layer of air so produced that 
 animals and plants chiefly flourish. Ascend a mountain's side 
 and a height is soon reached at which eternal snow and cold 
 prevail, where animal life cannot penetrate and even the low- 
 est forms of vegetable life can hardly make their residence. 
 What has thus far been said points out a valuable office of 
 water vapor, and one that is entirely in addition to that 
 which this same material performs as it floats in the clouds, 
 ready to fall as beneficent showers and then to proceed to the 
 other steps in the progress of that useful circulation w r hich it 
 performs as a liquid. But it may not be out of place to 
 mention here that the aqueous vapor in the atmosphere ap- 
 pears to serve in another way for man's pleasure, even 
 though in this particular no utility can be claimed. Thus 
 the glories of sunrise and sunset, which have delighted intel- 
 ligent beings for so many ages, are paintings upon the dra- 
 pery of the firmament which the pencil of light has been 
 enabled to produce through the medium of the refractive 
 power of those gathering drops of water which float about 
 in various forms and combinations in the morning or the 
 evening sky. 
 
 It has already been more than once declared that carbon 
 dioxide is poured out into the atmosphere by all the ordinary 
 
THE ATMOSPHERE. 181 
 
 processes of combustion. This is not only true of combustions 
 such as those of coal and wood and similar highly carbon- 
 aceous materials ; it applies with equal force to the animal 
 body itself, which has been properly likened to a furnace. 
 The air taken into the lungs at each breath inspired supports 
 during life a continual combustion, by reason of which 
 minute fragments of the animal tissue are burned in all parts 
 of the system. One of the products of this burning is car- 
 bon dioxide, which is carried to the lungs, thence to be ex- 
 haled as a waste product into the atmosphere. It might at 
 first be expected that this carbon dioxide would accumulate, 
 and form a constantly increasing proportion of the air. But 
 it is one of the proper foods of vegetable life ; for nature 
 has wonderfully provided that plants should thrive by the 
 absorption, or inhalation, of this particular gas. And so all 
 the leaves in the forest are continually cleansing the air of 
 that carbon dioxide that living animals have cast aside as a 
 useless thing. And by a magnificent alchemy, the result of 
 a wonderful and beneficent plan, they turn this waste mat- 
 ter of the animal frame into food for themselves, and they 
 cast out into the air as their refuse that oxygen gas which 
 living animals demand. So, then, the two forms of living 
 beings exist in a harmonious partnership by reason of which 
 each one is benefited. 
 
 An example similar to that just given with respect to car- 
 bon dioxide is found in ammonia gas. This substance is one 
 of the commonest products of the decay and decomposition 
 of animal matters. Wherever animal waste is deposited upon 
 the surface of the earth it quickly evolves ammonia gas. 
 This gas diffuses itself through the atmosphere under the in- 
 fluence of conditions whereby it may perform an important 
 service ; for it is always extremely soluble in water. And so 
 as soon as rain is condensed, whether in a gentle shower or 
 in abundant torrents, each drop in passing through the air 
 gathers ammonia and carries it down to the earth. Again, 
 ammonia is one of the chief foods for plants. And so the 
 rain drops, charged with such ammonia as they have been 
 
182 CHEMISTRY. 
 
 able to collect, bear it to the rootlets in the soil as a valuable 
 and important food, and one which has been proved to have 
 a most stimulating influence upon their growth. 
 
 There is not opportunity here for discussion of the offices 
 and the interplay of the other substances existing in atmos- 
 pheric air ; they are more local in their effects and more 
 difficult to trace and to describe. 
 
 The Air is not a Chemical Compound. 
 
 The importance of the atmosphere and its great abundance 
 have naturally led to most thorough scientific scrutiny of it. 
 Thus the amounts of its principal constituents have been 
 studied with extreme care. One result has been that the 
 principal constituents the oxygen and the nitrogen have 
 been found to exist in air in proportions singularly constant in 
 amount. This fact has suggested to some chemists the im- 
 pression that air is a true chemical compound. This latter 
 suggestion, however, appears not to be sustained by the most 
 rigid examinations that have been made. In fact they give 
 ample support to the opinion already declared that the air 
 consists of a mass of merely mingled gases, and that these 
 gases are uniformly maintained in their proper proportional 
 amounts by the beautiful interaction of the physical and 
 chemical forces with which they are endowed. 
 
 Fitness of Atmospheric Air for its Uses. 
 
 The statements already presented must have suggested to 
 the reader that the atmospheric air fulfills its offices in nature 
 much as any contrivance carefully devised by an intelligent 
 framer would accomplish the work for which it was planned. 
 Besides those chemical adaptations which have been the prin- 
 cipal grounds upon which this line of thought has been sup- 
 ported here, there are others which may be briefly suggested. 
 
 By reason of the mobility of air, as well as its tendencies 
 to expansion by heat, our atmosphere is necessarily in a state 
 of most intricate ebbing and flowing. One prominent effect 
 of the motion thus set up is to cause a transfer of warm air, 
 
THE ATMOSPHERE. 183 
 
 and so a distribution of heat, from more favored portions of 
 the globe to the others. 
 
 This same result is also more completely attained by the 
 influence of the specific heat of air. Atmospheric air has re- 
 markable power in which it resembles to some extent water 
 to take up a very large amount of heat with but a slight rise 
 in temperature ; similarly a slight fall of temperature is asso- 
 ciated with a large evolution of heat. By reason of these 
 properties air, like water, has an exceptional storage power for 
 heat. This contributes largely to the equalization of climates. 
 
 The elasticity of the atmospheric air permits it to be- 
 come a useful servant of man in the transmission of sound. 
 Thus human beings and with less distinctness most of the 
 living creatures of the lower orders communicate their 
 thoughts by means of spoken words through that line of at- 
 mospheric air extending from them to their hearer or hearers. 
 
 Again, the characteristics of the atmosphere are such that it 
 diffuses sunlight. By this is meant that in air sunlight does 
 not confine itself to those strictly straight lines which it fol- 
 lows in empty spaces. So then this property of air mitigates 
 the blackness of shadows, and, for example, he who walks into 
 a shady lane does not plunge into absolute darkness, as he 
 might if we were deprived of this beneficial diffusing in- 
 fluence of the atmospheric air. 
 
 The two considerations last adduced contribute much 
 toward making the earth a cheerful home for human beings; 
 for they aid materially in the distribution of intelligible ideas. 
 Moreover those properties of air by virtue of which its un- 
 dulating waves make music possible, and further those which 
 permit the flight of light, and so allow of the existence of 
 the graphic arts, certainly make no mean contributions to the 
 happiness of man ; thus they help to furnish the earth as his 
 place of residence. 
 
 READING REFERENCE. 
 Atmosphere, Selective power of, for heat rays. 
 
 Langley, S. P. Science, v, p. 450, 
 
184 CHEMISTRY. 
 
 XXII. 
 
 EXPLOSIVES. 
 
 IHE principal explosives owe their activity, to a very 
 large degree, to the presence of nitrogen in them 
 thus they may properly be discussed in connection 
 with that element. 
 The explosives of chief importance are four in number : 
 gunpowder, the fulminates, gun-cotton, nitroglycerin. From 
 this list arises a suggestion of the uses of these substances in 
 warfare ; but it must not be forgotten that they have also 
 important applications in the arts of peace. Thus, enormous 
 quantities of gunpowder and nitroglycerin are used in blast- 
 ing operations, for purposes like the removal of rock prepara- 
 tory to laying foundations for large buildings, as well as in 
 excavations for railway cuttings and in the boring of tunnels ; 
 also in the getting of building stone from quarries, the tear- 
 ing of ore out of mineral bearing veins in mining operations ; 
 and for loosening coal in coal pits. Large quantities are 
 likewise employed in pyrotechnics. It must not be forgotten 
 that fireworks are not only for purposes of night illuminations 
 and for public gratification in times of popular rejoicings ; 
 they are also employed to a considerable extent for such use- 
 ful purposes as night signaling in connection with vessels at 
 sea. 
 
 The use of gunpowder may be mentioned also in its con- 
 nection with the life-saving stations on the sea-coast. It is 
 a charge of gunpowder in a mortar that propels a cannon-ball 
 having a line attached to it to a vessel in distress. 
 
 Gunpowder. 
 
 Of the various explosives mentioned, gunpowder is the 
 oldest. While the invention of this substance has often been 
 referred to Roger Bacon, the celebrated English friar who 
 
EXPLOSIVES. 185 
 
 died about 1292, it is now conceded that, though Bacon evi- 
 dently knew the composition of it, the original invention dates 
 far earlier than his times. There seems foundation for the be- 
 lief that it is at least a thousand years old, while its use in artil- 
 lery at the battle of Crecy shows its employment in warfare 
 
 FIG. 45. Roger Bacon, born near Ilchester, about 1214 ; died, probably at Oxford, in 
 1292. 
 
 for over five hundred years. Bacon's power of independent 
 thought placed him so far in advance of the century in which 
 he lived that he became an object of persecution, but he is 
 at present ranked as one of the prominent figures of history. 
 In his works Bacon refers to a substance that seems to corres- 
 pond to gunpowder, and in terms that suggest that he consid- 
 ered it as a material of not uncommon knowledge in his day. 
 
186 CHEMISTRY. 
 
 The principal constituents of gunpowder are three: potassic 
 nitrate, charcoal and sulphur. The chemical action between 
 potassic nitrate and charcoal in gunpowder may be better 
 understood after a simple experiment, which any one can try. 
 The experiment referred to is as follows : take a large piece 
 of charcoal ; heat it over a spirit lamp or gas lamp until cer- 
 tain portions of it take fire so as to burn with a slight glow ; 
 next, sprinkle very carefully a small amount of powdered 
 potassic nitrate also called both saltpetre and nitre upon 
 the glowing part. A burning, something like that of gun- 
 powder, only less violent, results. The potassic nitrate has 
 the formula KNO 3 . When it falls upon the glowing coal a 
 portion of the oxygen leaves the other constituents of the 
 saltpetre and accomplishes thereby a true combustion of the 
 carbon. One important factor in the operation is the element 
 nitrogen ; owing to the general inertness of nitrogen it easily 
 allows the escape of other elements combined with it. So, in 
 case of the experiment just suggested, the combustion of the 
 charcoal is referable to oxygen liberated by reason of the 
 feeble affinity of one of the other constituents of the potassic 
 nitrate that is, the nitrogen. Thus far the only thing partic- 
 ularly suggested is the combustion that takes place ; another 
 point of importance may be mentioned in this connection. 
 If finely powdered charcoal and potassic nitrate are thoroughly 
 intermingled and then set on fire in a closed vessel, a large 
 amount of gas, carbon dioxide, will be generated by the com- 
 bustion ; arid this gas may burst the vessel unless it is a very 
 strong one. If, however, the vessel has an opening supplied 
 with a cork or plug, this stopper will be violently driven out 
 by reason of the explosive force of the carbon dioxide gener- 
 ated. So, in the preparation of gunpowder, potassic nitrate, 
 charcoal, and the third substance, sulphur, are finely pulver- 
 ized and carefully intermingled. Thus they are brought to a 
 state of thorough diffusion and intimate contact. The offices 
 of carbon and potassic nitrate have been already explained. 
 The office of the sulphur is principally to combine with the 
 potassium of the potassic nitrate, yielding as a result a 
 
EXPLOSIVES. 187 
 
 somewhat larger evolution of gas. At all events, when gun- 
 powder is consumed, two important results are afforded. As 
 already intimated, the first is the sudden liberation of a very 
 large amount of gas carbon dioxide. The second is that 
 this gas is generated by a process of true combustion attended 
 with great heat, the latter contributing largely to the ex- 
 plosive force by reason of the great expansion of the gaseous 
 products effected by the heating. 
 
 There are several different kinds of gunpowder, but they 
 all consist essentially of the constituents mentioned. Their 
 differences are either in the proportions of the constituents 
 used or in the size of the granules in which the powder is 
 formed. Thus for some war purposes it is requisite that the 
 powder should burn very rapidly, while in others it is required 
 to burn slowly. For the purpose of regulating the rate of 
 combustion, the grains are made of various sizes. The smaller 
 sizes burn more quickly, while those of larger dimensions, as 
 well as those more strongly compressed, burn more slowly. 
 
 While the exact chemical changes which take place when 
 gunpowder burns are too complicated to admit of discus- 
 sion here, they are in the main those just explained. 
 
 Fireworks. 
 
 Gunpowder affords the basis of the pyrotechnic art. It is 
 employed also with the distinct intention of utilizing both of 
 those prime properties already referred to. That is to say, 
 by reason of its explosive force, gunpowder produces the var- 
 ious forms of motion and the loud reports requisite in fire- 
 works. By reason of the intense heat afforded by its com- 
 bustion, the various kinds of light are producible. The truly 
 marvelous effects obtained by the skilled pyrotechnist involve 
 the use of a great multitude of substances and also an ingen- 
 ious mechanical combination of them. 
 
 So many forms and combinations of fireworks are pos- 
 sible that no enumeration can be made here ; moreover, their 
 infinite capabilities depend upon the inventive resources and 
 skill of the maker. In a brief description, the rocket may be 
 
188 CHEMISTRY. 
 
 taken as the type of fireworks. It is often of most ingenious 
 construction. Thus it may be provided with many chambers, 
 one connecting with another by proper passages. In these 
 passages are placed fuses so that the fire shall run from one 
 chamber to another in proper order. Of course the main 
 barrel contains a quickly burning gunpowder. This is for 
 the purpose of producing the ascent. It is well known that 
 a pistol, a rifle or a cannon always experiences a strong 
 recoil when fired. So does a rocket ; but the rocket is 
 so constructed that the recoil is the chief factor in its first 
 discharge. That is, in the case of the rocket, the discharge 
 is downward and the recoil upward ; so that in fact the 
 ascent of the rocket is due to what may be called an ex- 
 ceedingly powerful recoil. When the rocket is high in air, 
 the fuse connected with its principal barrel lights its sub- 
 ordinate chambers, and these then exploding distribute into 
 the sky the brilliant masses of stars or other graceful pieces 
 originally intended. The loud reports that take place at such 
 times are due to portions of violently explosive substance 
 within certain chambers, while the party-colored lights pro- 
 duced are referable to the burning of substances which have 
 been carefully selected for the purpose. Thus the pyrotech- 
 nist has recourse to mixtures of gunpowder and various other 
 chemical substances to produce colored fire. Finely powdered 
 charcoal or lamp-black give rise to a red fire : so also do most 
 of the salts of strontium. Common salt or powdered resin give 
 rise to yellow fire. Copper filings and certain salts of copper 
 produce greenish hues ; so do salts of birium. Zinc filings 
 and chloride of copper, and certain others, produce blue 
 shades. Saltpetre, in considerable quantity, affords a delicate 
 pink ; while iron filings and steel filings and magnesium filings 
 produce scintillations of great brilliancy. 
 
 Fulminates. 
 
 The fulminates are substances that are so extremely un- 
 stable in chemical character that they require but a very 
 slight mechanical blow to decompose them. Two fulminates 
 
EXPLOSIVES. 189 
 
 in particular may be mentioned : fulminate of mercury and 
 fulminate of silver. They are both viewed as salts of a pe- 
 culiar complex acid called fulminic acid. This acid is a com- 
 pound of carbon, hydrogen, oxygen and nitrogen. When 
 silver or mercury takes the place of the hydrogen in fulminic 
 acid, the dangerous salts just mentioned are obtained. Ful- 
 minating mercury is the onu of chief use. It is employed in 
 percussion caps. A drop of gum is put in the inside of the 
 cap, then the exact amount of fulminate in the form of a 
 powder is allowed to fall into the gum ; finally the whole is 
 allowed to harden. When the cap is used, a violent blow 
 from the hammer of the gun or pistol gives rise to the ex- 
 plosion of the fulminate, and this communicates to the gun- 
 powder of the cartridge to be fired. Fulminating silver is too 
 dangerous for use in percussion caps, but it is employed in 
 certain explosive toys like torpedoes. 
 
 Gun-cotton. 
 
 Gun-cotton is a chemical modification of the ordinary 
 cotton fibre. This fibre, when purified by chemical washings, 
 consists entirely of the substance called cellulose, composed 
 of carbon, oxygen and hydrogen. It is not different from 
 certain other vegetable fibres. 
 
 When clean cotton is acted upon by strong nitric acid it 
 undergoes the wonderful chemical change to gun-cotton : 
 without material alteration in its physical appearance there 
 has been a chemical substitution by reason of which a nitro- 
 gen compound has been introduced into the chemical mole- 
 cule, as a substitute in place of certain of the hydrogen atoms 
 originally present. 
 
 On this account gun-cotton is often spoken of as trinitro- 
 cellulose. By reason of this chemical substitution the cot- 
 ton changes as if by magic from the simple, safe material 
 ordinarily known, to one of the most dangerous of explosives. 
 Thus Mr. Abel, the chemist to the English War Department, 
 who has made a series of most careful studies of gun-cotton 
 with reference to its use for war purposes, finds the explosive 
 
190 CHEMISTRY. 
 
 power of gun-cotton to be more than fifty times that of gun- 
 powder of equal weight. One of the greatest objections to 
 the use of gun-cotton is found in the fact that, upon keeping, 
 it undergoes of itself a steady decomposition resulting ulti- 
 mately in dangerous explosions. This fact appears to be 
 likely to prevent the substance coming into general use. 
 
 Nitroglycerin. 
 
 Glycerin produced at present in enormous quantities from 
 fats and oils is well known as a sweetish, oily and harmless 
 substance. Glycerin is composed of carbon, hydrogen and 
 oxygen in proportions but slightly different from those in 
 cotton. Thus its formula is 
 
 C 3 H fi O 3 II 3 . 
 
 If this bland and simple material is subjected to the action 
 of concentrated nitric acid, it undergoes a change very 
 similiar to that recognized in the case of cotton as just de- 
 scribed. It then produces a compound called trinitroglycerin, 
 which, while it ranks as one of the most powerful and use- 
 ful explosives, it is also associated with a long list of horrible 
 disasters produced by accidental, or in some cases intentional, 
 explosions of it. 
 
 Nitroglycerin is itself an oily material, and it was first con- 
 siderably used in that form. The terrible accidents from 
 transportation of the article have given rise to the adoption of 
 two means for lessening the risks attending it. The first is 
 the manufacture of the substance in suitable localities that 
 is, near to great public works in which it is to be employed. 
 And, again, the factories are so arranged that the operations 
 of the manufacture shall be conducted in small buildings sur- 
 rounded by earthworks sufficient to localize any explosion 
 that might unhappily occur. 
 
 At the manufactory of explosives at Ardeer, on the Scotch 
 coast, about fifty miles from Glasgow, a most ingenious ad- 
 ditional precaution is taken. Here each laborer, as he enters 
 
192 
 
 CHEMISTRY. 
 
 the works in the morning, passes into a cottage to change his 
 dress. He dons a uniform of a special and distinctive color 
 it may be scarlet, or bright blue or white or gray, accord- 
 ing to the department in which he is employed. Thus the 
 policemen who are constantly on duty can detect at once any 
 employe who strays into a department to which he does not 
 belong and where his lack of acquaintance with the processes 
 might lead to a terrible accident. 
 
 Another special device is the invention of Albert Nobel, 
 who has been noted as the principal person by whose efforts 
 nitroglycerin has been introduced into the 
 important uses which it finds at the present 
 day. This is the absorption of the liquid nitro- 
 glycerin in some spongy material, such as will 
 serve as a safe and proper vehicle for the ex- 
 plosive. The substance thus employed is a kind 
 of fine silicious earth called diatomaceous earth, 
 also infusorial earth. This is a mineral material 
 found in various parts of the world in somewhat 
 abundant deposits. Upon examination by the 
 microscope it is found to be composed of the 
 mineral skeletons of microscopic organisms. 
 (See page 252.) This substance by virtue of 
 its minute cellular texture seems to be admi- 
 rably fitted to imbibe the liquid nitroglycerin, 
 and assist in packing it in proper cartridges. 
 The explosive produced by the combination 
 
 FIG. 47.-Dynamite j s tne one CO mmonly known as dynamite.* 
 Exploder. / , \ 
 
 A peculiarity of nitroglycenn and dynamite 
 
 is that they cannot be fired in the ordinary fashion. That 
 is, if a lighted match is brought to them they may take fire 
 and burn with perfect quietness. For their explosion they 
 demand some kind of violent blow. For this reason their 
 cartridges have to be provided with special exploders. These 
 are small cases of gunpowder, or, perhaps, fulminating mate- 
 rials, which may be set on fire by means of a powder fuse or 
 * Dynamite is pronounced, dln'am-lt. 
 
I 
 
 8 
 
 
 
EXPLOSIVES. 193 
 
 an electric current ; their explosion within the nitroglycerin 
 mass determines a violent shock to the latter. It is the con- 
 cussion thus produced that is the appropriate means of ex- 
 ploding the nitroglycerin or dynamite cartridges. 
 
 While sad accidents with these materials have horrified 
 the whole world by their sudden and disastrous results, it is 
 too often forgotten that their gigantic forces are day by day 
 safely and quietly contributing to the execution of great pub- 
 lic works all over the earth. Thus, in the great rock tunnels 
 of Mont-Cenis and St. Gothard, which pierce the Alps, nitro- 
 glycerin and dynamite have done the work of armies of men. 
 In the St. Gothard tunnel more than two million pounds of 
 dynamite have been employed, and it has proved wonderfully 
 effective in advancing most arduous subterranean work. 
 
 Dynamite has been used with success by Arctic explorers 
 to open passages in the ice. The following item, from a 
 recent American Associated Press dispatch, shows a similar 
 application of this explosive: 
 
 DOVER, N. H., Feb. 15, 1888. It was expected by many 
 that the railroad bridge at Dover Point would completely 
 collapse with the out-going tide to-night by the action of 
 the ice, but this did not occur. Some very large cakes of 
 ice came down to the bridge, one piece being over 500 feet 
 long, but the presence of thousands of smaller pieces 
 about the bridge prevented it from doing harm. A gang of 
 men has been employed all the afternoon and evening 
 breaking up the ice field between the bridge and Fox Point, 
 a distance of two miles, with dynamite cartridges, and 
 they have been very successful. 
 
 An unsurpassed illustration may be found in the destruc- 
 tion of Flood Rock, in the swift and dangerous channel 
 called Hell Gate, near New York city. After the failure of 
 many previous attempts to remove this obstruction, Gen. 
 John Newton, of the U. S. Army, recommended exploding it, 
 after thoroughly tunneling it underneath. The preparatory 
 work occupied seventeen years, that is, from 1868 to 1885. 
 Finally the drill holes in the mine were supplied with their 
 cartridges, more than 42,000 in number, and weighing over 
 282,000 pounds; and on October 10, 1885, the largest 
 mass of explosives ever fired at once performed, its office in 
 the interests of commerce and industry, and Flood Rock 
 13 
 
194 CHEMISTRY. 
 
 became a mere mass of debris, which will gradually be re- 
 moved by dredging. 
 
 Unquestionably, then, the principal use of dynamite is in 
 the labors of peace. Still, nitroglycerin and dynamite have 
 come into great prominence by reason of their use in naval 
 warfare. Torpedoes of a great variety of forms are now con- 
 structed so that a quick-moving launch may steam up to a 
 large ship of war, place close to her side one of these danger- 
 ous contrivances, and then quickly withdraw in time to avoid 
 the effects of the explosion, which involves the great vessel 
 in devastating ruins. Torpedoes charged with nitroglycerin 
 or dynamite are also used for the defense of harbors, being 
 sometimes placed in such a way that an enemy's ship, in 
 crossing the line formed by the torpedoes, shall by that act 
 explode one or more of them and produce her own destruction. 
 
 READING REFERENCES. 
 
 Dynamite, Manufacture of. 
 
 La Nature, p. 154 (Feb. 4, 1888.) 
 Explosive Agents. 
 
 Abel, F. A. Jour, of Chem. Soc. of London, xxiii, 41, xxvii, 536. 
 
 Chem. News. xxxix, 165, 187, 198, 208. 
 Explosives, A New Class of. 
 
 Sprengel, H. Jour, of Chem. Soc. of London, xxvi, 796. 
 Explosives, Force of. 
 
 Berthelot. Annales de Chimie et de Physique. 4 Ser. xxiii, 223. 
 Explosives, in Blasting. 
 
 Scribner's Monthly, iii. 33. 
 Explosives, Literature of. 
 
 Munroe, Chas. E. Proceedings of U. S. Naval Institute, No, 35 
 
 (referred to in Chem. News. liv, 308). 
 Explosives, Use of, at Flood Rock (Hell Gate N. Y.) 
 
 Derby, Geo. McC. Sanitary Engineer, xiii. 9. New York. 
 Greek Fire, (so called). 
 
 Lalanne, L. Anriales de Chimie et de Physique. 3 Ser. iv, 433. 
 Gun-cotton, Manufacture and Composition of. 
 
 Abel, F. A. Jour, of Chem. Soc. of London, xx, 311, 505. 
 Gunpowder, Chemical Theory of. 
 
 Debus, H. Chemical News, xlv, 91. 
 
PHOSPHORUS. 195 
 
 XXIII. 
 
 PHOSPHORUS. 
 
 is a most interesting chemical ele- 
 ment. This is because of its exceptional chemical 
 properties, the very important part it plays in the 
 chemistry of animal and vegetable life, and its 
 employment in the friction match, one of the most conven- 
 ient and useful articles of human invention. 
 
 Phosphorus appears to have been tirst prepared in the 
 year 1669 by a Hamburg merchant named Brandt, who be- 
 came fascinated with the study of alchemy and pursued his 
 experiments with the hope of repairing his broken fortunes 
 by the discovery of the philosopher's stone. The happy 
 discovery of phosphorus, while it did not enrich him, at least 
 preserved his name in the annals of chemistry. Brandt pro- 
 duced it, by a laborious process, from certain animal matters. 
 Notwithstanding the remarkable properties of the substance 
 and the extraordinarily useful purposes to which modern 
 scientific knowledge has applied it and its compounds, phos- 
 phorus remained the merest toy for more than a hundred 
 years. In 1771 Scheele revealed to the world the fact that 
 it may be prepared from bone-ashes that is from burnt bone 
 and this has ever since been found to be its most conven- 
 ient source. 
 
 The name phosphorus is derived from two Greek words 
 (</>w phos, light, and, 0epw pkero, I bear) which suggest one 
 of its marked properties ; namely, its power of continually 
 affording light, even though not set on fire after the manner 
 of ordinary illuminating materials. It is true the light is 
 feeble, and chiefly noticeable in the dark. It is the same, in 
 fact, as that yielded in the dark by an ordinary friction 
 match when it is gently rubbed, but has not yet taken fire. 
 This light, however, is the product of a true combustion, only 
 
196 CHEMISTRY. 
 
 of a very slow one; and again this burning of phosphorus is 
 initiated by heat, (though only a very moderate amount is 
 required for it). Of course, for phosphorus, much less heat 
 is demanded than to set on fire our ordinary combustibles. 
 
 Sources of Phosphorus. 
 
 Phosphorus, though very widely distributed in nature, is 
 never found free or uncombined. This fact is distinctly 
 referable to the ease with which the substance combines 
 with oxygen ; if it were found free at any point on the sur- 
 face of the earth where it suffered exposure to atmospheric 
 air, it would of course quickly enter into combination with 
 oxygen. 
 
 Phosphorus exists occasionally in the earth in the state of 
 combination in very hard rocky masses, of which the mineral 
 known as apatite composed mainly of calcic phosphate 
 is a good example. It is also present in small quantities in 
 almost all soils; and in minute quantities in most natural 
 waters, like river-water and sea-water. 
 
 One of the most familiar substances containing phosphorus 
 is the bony skeleton of the higher animals. Here also it 
 exists as calcic phosphate. It exists also in the brain, 
 though in a 'form of chemical combination not easily stated. 
 
 Further, it is a constituent of various portions of the vege- 
 table structure, especially of seeds. 
 
 Agricultural Uses of Phosphorus. 
 
 The statements in the last two paragraphs have been pre- 
 sented with the express purpose of calling attention to the 
 important offices of phosphorus in connection with animal 
 and vegetable life. Thus exact experiments have shown 
 that plants do not flourish in soils barren of phosphates, and 
 that the mere addition of almost any soluble phosphate 
 to an arid soil promptly stimulates the plant living upon 
 it into more luxuriant growth. These facts have led to 
 the introduction into commerce of artificial fertilizers con- 
 
PHOSPHORUS. 19? 
 
 taining soluble phosphates as their principal ingredients ; and 
 the manufacture of such fertilizers has continually expanded, 
 until now it is conducted by the principal commercial nations 
 on a truly gigantic scale. For the purpose of this manufact- 
 ure bones are particularly favorable because of their poros- 
 ity. In fact, the surface of the world is ransacked to supply 
 this raw material. Thus from the deserts of Africa bones 
 are conveyed as far as England to be manufactured into 
 fertilizers; and so from the great western plains of the United 
 States bones are brought to the eastern centres for a like use. 
 
 The agricultural demand for phosphates of some sort has 
 become so imperious that even apatite is now largely used, 
 notwithstanding the difficulties that its exceedingly hard 
 and compact structure places in the way of the manufac- 
 turer. 
 
 From the plant phosphorus finds its way, in the form of 
 food, into the animal system. The living animal appreciates 
 this essential ingredient, carefully selects it out from the 
 food, and stores it up both in its brain and in its bony frame- 
 work. This framework is exceedingly important as giving 
 the requisite rigidity to the whole structure, the proper sup- 
 port for the action of the various muscles, and protection for 
 the softer organs. 
 
 Preparation of Phosphorus. 
 
 Phosphorus itself is prepared by a process too complicated 
 for the ordinary amateur chemist to repeat; indeed, its prep- 
 aration, even on the large scale, presents serious difficulties. 
 These are associated with the great combustibility of the 
 substance, which makes necessary extraordinary precautions 
 against fire. Again, laborers in phosphorus works are sub- 
 ject to a painful and incurable disease called phosphorus 
 necrosis, which has a peculiar and destructive effect upon the 
 bones of the jaw. Finally, the chemical changes involved 
 give rise to such difficulties and complexities as force the 
 manufacturer to unusual watchfulness. In fact, it has been 
 recently stated that there are scarcely more than two facto- 
 
198 
 
 CHEMISTRY. 
 
 ries for phosphorus manufacture in the world one in En- 
 gland and one in France. 
 
 The element phosphorus, as ordinarily seen, has much the 
 appearance of wax. It has a white or amber color, and is 
 translucent; it may be cut with' a knife much as wax cuts. 
 It is ordinarily sold in the form of cylinders of about half an 
 inch in diameter. It is necessary to keep it in vessels of 
 water, for, as already stated, if exposed to the air it would 
 
 FIG. 48. Coignet's apparatus for production of red phosphorus. Ordinary phos- 
 phorus is placed in a cast-iron vessel c ; it is then heated ten or twelve days, an even 
 temperature being maintained by the two iron jackets, one inclosing sand, the other 
 holding fusible alloy. 
 
 oxidize. This oxidation, at first slow, increases in vigor from 
 the heat afforded by the portions oxidized first. After a 
 short exposure to air a stick of phosphorus spontaneously 
 bursts into flame. Evidently, then, phosphorus should not 
 be handled except under water. Cases are recorded of 
 severe and even fatal burns the result of handling phos- 
 phorus in the air. 
 
 We may with propriety call attention here to another 
 peculiarity of phosphorus, which constitutes one of the re- 
 markable features of this interesting element. About thirty- 
 five years ago a Vienna chemist, von Schrotter, discovered 
 
PHOSPHORUS. 190 
 
 that when phosphorus is heated for a considerable length of 
 time, under conditions such that no gas is present which can 
 act chemically upon it, it undergoes a marked change in its 
 properties. Thus its color turns to red,' and, strange to say, 
 it loses altogether that ready combustibility which is the 
 most striking characterstic of ordinary phosphorus. It may 
 seem incredible that any such change could in fact occur. 
 But this red phosphorus has become an article of considerable 
 importance in commerce, and it is a well-established fact that 
 ordinary phosphorus may be turned into this modification 
 without any gain or loss of weight, and that, on the other 
 hand, this red phosphorus may be turned back again, by 
 suitable processes, to the ordinary form, also without gain 
 or loss of weight. Phosphorus is not the only elementary 
 substance that is capable of this kind of change. Indeed, 
 the general term allotropism has been applied to the tendency 
 of elementary substances to undergo internal changes, by 
 reason of which their chemical properties are temporarily 
 modified without gain or loss of weight, and therefore inde- 
 pendently of chemical combination or decomposition. (See 
 page 121.) 
 
 Chemical Properties of Phosphorus. 
 
 The chemical properties of phosphorus are wide in their 
 range that is, it combines with many of the chemical 
 elements. Thus it unites with hydrogen in several pro- 
 portions, and thereby forms several compounds, called phos- 
 phuretted hydrogen. As might be expected, they are all ex- 
 ceedingly combustible ; one of them, in particular, takes fire 
 at ordinary temperatures immediately upon coming in con- 
 tact with the atmosphere. Its production affords opportunity 
 for a beautiful experiment, though a somewhat dangerous one. 
 When the gas is produced in a retort it may be made to 
 bubble through water in the form of vapor in company with 
 various other gases generated at the same time. Then, as it 
 reaches the surface, it instantly takes fire, the phosphorus 
 burning to a white, smoke-like substance which usually floats 
 
200 CHEMISTRY. 
 
 away in forms similar to those of smokers' rings. The 
 smoke consists of minute particles of a solid, called phos- 
 phorus pentoxide, and expressed by the formula P 2 O 5 . This 
 is evidently the product of the combustion of that phos- 
 phorus which is a part of the inflammable gas. The shape of 
 the rings is due to a mere mechanical circumstance, and the 
 same in effect as that afforded by the lips of the smoker while 
 producing rings. Indeed, if a paper box, having a round hole 
 
 FIG. 49. Phosphuretted hydrogen gas, of tbe spontaneously Inflammable variety, 
 taking fire in air and forming smoke-rings. 
 
 on one side, be filled with smoke of any kind, sharp blows 
 upon the opposite side will drive out portions of the smoke 
 in such a way as to produce similar rings. Such rings are 
 often seen on a still day puffed out of the smokestack of a 
 locomotive, and they are sometimes produced by the dis- 
 charge of a cannon in still air. The fact is that in all these 
 cases the portion of smoke producing a ring advances through 
 the opening with a sudden impulse, the edge of the opening 
 retarding those particles that pass nearest to it. Thus the 
 delayed particles acquire a tendency backward and inward 
 which starts them on the peculiar series of circular courses, 
 which in the grand aggregate gives rise to the rings. 
 
 As has more than once been stated, phosphorus has a 
 marked affinity for oxygen. It burns in any vessel contain- 
 
PHOSPHORUS. 201 
 
 ing air, combining with oxygen in such a way as to readily 
 deprive the air of the entire amount of this element contained 
 in it. 
 
 The chemical change is represented by the following 
 equation : 
 
 P 2 -f 5O 2 2P a O s 
 
 One molecule of Five molecules of Two molecules of 
 
 Phosphorus, Oxygeu, Phosphorus pentoxide, 
 
 124 160 284 
 
 parts by weight. parts by weight. parts by weight. 
 
 V y 1 V ^ > 
 
 284 284 
 
 When the operation is performed in a tall jar the oxide 
 of phosphorus produced falls as abundant flakes having a 
 snow-like consistency. When these flakes are thrown upon 
 water they chemically combine with the water, affording 
 much heat and producing a hissing sound which is the 
 evidence of it. The liquid now acquires a sour taste, refer- 
 able to the fact that phosphoric acid has been produced. 
 
 The chemical change is represented by the following 
 equation : 
 
 P 2 5 + 
 
 3H 2 = 
 
 2H 3 P0 4 
 
 One molecule of 
 
 Three molecules of 
 
 Two molecules of 
 
 Phosphorus pentoxide, 
 
 Water, 
 
 Phosphoric acid, 
 
 142 
 
 54 
 
 196 
 
 parts by weight. 
 
 parts by weight. 
 
 parts by weight. 
 
 196 196 
 
 Phosphoric acid is the starting-point of an immense series 
 of salts called phosphates. One of these, calcic phosphate, we 
 have already referred to as existing in bones and in apatite. 
 
 Friction Matches. 
 
 The earliest method of producing flame appears to have 
 been by the friction of pieces of dry wood in contact with 
 dry leaves or similar combustible substances. This method 
 travelers have found to be still in use among tribes of a low 
 stage of development. The next method seems to have been 
 
202 CHEMISTltY. 
 
 by the use of flint and steel and tinder. When the flint is 
 sharply struck against the steel it tears off minute particles 
 of the metal, and these fragments are heated to the luminous 
 point by the violence of the stroke ; if they are made to fall 
 upon the tinder this easily combustible material takes fire; 
 from its burning a candle or lamp may be lighted. But the 
 flint and steel and tinder must be dry and in good order, to 
 produce the best results ; even then considerable skill is de- 
 manded. So it is easy to see that mankind has often pre- 
 ferred to preserve aflame once lighted^ and then communicate 
 this to another and another from time to time, rather than to 
 go to the trouble of exciting a new combustion when fire was 
 needed. And it is easy to appreciate the usefulness to its 
 possessor of a flame once kindled and the serious incon- 
 venience resulting from its extinction. Thus we can readily 
 comprehend how some nations have adopted fire as a deity to 
 be worshiped, and considered it worthy to be preserved con- 
 tinuously unextinguished, and to be guarded with religious 
 care. 
 
 The flint and steel method has ample illustration as to its 
 principle, not only in familiar cases like sparks from the 
 horse's hoof, but also in many processes in factories and 
 machine-shops. Here it is well known that the grindstones 
 used for finishing articles of iron and steel send off from their 
 work an uninterrupted current of minute chips of the hot 
 and luminous metal. 
 
 This method of obtaining fire held its own until about 
 sixty years ago. In 1829 a kind of chemical match was de- 
 vised, and soon after, in 1832, a true friction match containing 
 phosphorus was brought into use. The principles upon which 
 the phosphorus match depends are but very slightly different 
 from those involved in the use of the flint and steel. Thus in 
 the ordinary friction match the rubbing upon the rough sur- 
 face is a mechanical process which generates heat, just as any 
 blow or any friction does. In the case in question the 
 amount of heat is small, but it is sufficient to set on fire the 
 small amount of phosphorus on the tip of the match ; the 
 
PHOSPHORUS. 
 
 phosphorus sets on fire the sulphur which coats over the end 
 of the match ; the sulphur in burning sets on fire the wood 
 of the match, and here the combustion has reached a stage at 
 which it is easily communicated to larger masses of material. 
 In the finer kinds of wooden matches, in order to avoid the 
 objectionable smell of burning sulphur, this latter substance 
 is sometimes replaced by a thin coating of wax upon the end 
 of the stick. In this case other chemicals are added to the 
 tip of the match, in order to make the combustion more 
 active. 
 
 Friction matches of the ordinary kind are now so abundant 
 and familiar every- where that the exceeding usefulness, con- 
 venience and importance of the match as a device or in- 
 vention is apt to be overlooked. It is not intended to dwell 
 here upon this subject, however, for perhaps what has been 
 said of the appliances for lighting used in the past, renders 
 unnecessary further presentation of the principles utilized in 
 the little tapers of to-day. 
 
 As an article of manufacture the individual match is so 
 small that it is not easy at first to appreciate the greatness 
 of the commercial interest it represents. Thus it is estimated 
 that in Europe alone fifty thousand persons are constantly 
 employed in the manufacture of the various kinds of matches. 
 Again, though the amount of phosphorus used in each match 
 is very minute, its sum total is no less than a thousand tons 
 a year. The value of the annual product of this industry is 
 not far from fifty millions of dollars. 
 
 If there were introduced here an account describing at 
 length the manufacture of the friction match commencing 
 at the beginning, with the special kind of wood employed and 
 the processes used for its subdivision into the requisite frag- 
 ments, continuing even so as to explain the various contriv- 
 ances for packing the finished product that description 
 might be of interest ; but the special topic seems to be more 
 properly the preparation and application of the material at 
 the tip of the match. The sticks having been prepared, 
 they are placed, by machine, in frames capable of containing 
 
204 CHEMISTRY. 
 
 large numbers of them. They are first sulphured that is, 
 their ends are dipped in melted sulphur and it is allowed to 
 harden upon them. For the finer grade of matches, however, 
 the sulphur must be dispensed with, and instead the sticks 
 are dipped into melted wax. 
 
 In any case, they are next tipped with the highly inflam- 
 mable material, this process being called chemicking. The 
 inflammable paste is prepared in large quantities by mixing 
 the proper ingredients in a kettle surrounded by boiling 
 water. First, a solution of an appropriate gum or glue is 
 made. When it has attained a proper consistency, the 
 phosphorus is introduced little by little. The whole mass is 
 then slowly but thoroughly agitated with a wooden stirrer 
 until the phosphorus is diffused through the mass. Finally, 
 other ingredients, such as potassic nitrate or binoxide of lead 
 or manganese dioxide, which favor combustion, are added ; 
 and certain coloring matters, such as Prussian blue or ver- 
 milion, are introduced. Here is a German recipe for making 
 this paste : 
 
 Gum, 16 parts. 
 
 Phosphorus, 9 parts. 
 
 Potassic nitrate, 14 parts. 
 
 Manganese dioxide, 16 parts. 
 
 As has already been intimated, all of these substances, 
 except the phosphorus, may be replaced by others, according 
 to the style of the article to be manufactured or the views of 
 the maker. The process of chemicking consists in dipping 
 the sulphured ends into the inflammable paste, which for this 
 purpose is spread out on a stone slab. Finally, the tips are 
 coated over with a thin varnish to protect them from absorp- 
 tion of moisture. 
 
 At present the manufacture of friction matches is carried 
 on to a very large extent in Sweden, and that country, it is 
 now stated, produces about seventy-five per cent, of all the 
 matches made in the world. In Sweden, too, are largely 
 manufactured what are called safety matches. The safety 
 matches are tipped with a composition of potassic chlorate, 
 
PHOSPHORUS. 
 
 205 
 
 potassic dichromate, red oxide of lead, and sulphide of anti- 
 mony. Under ordinary circumstances friction will not set 
 these matches on fire. In lighting, they must be rubbed on 
 a prepared surface which contains principally red phosphorus 
 and sulphide of antimony. When the match is rubbed upon 
 this surface, the postassic chlorate of the match and the red 
 phosphorus of the friction-surface start a chemical combi- 
 nation which extends to the other materials on the tip of 
 the match. Safety matches, then, involve an invention 
 which in accomplishing its purpose affords a twofold advan- 
 
 FIG. 50. Pan, or water-bath, for melting and mixing the inflammable paste for 
 match tips. 
 
 tage. In the first place, as the match lights only on the pre- 
 pared surface, the danger of conflagrations from accidental 
 ignition of them is very largely reduced. This costly feature 
 of the ordinary phosphorus match would be largely, if not 
 entirely, done away with by general use of the safety match. 
 In the second place, the use of red phosphorus has the advan- 
 tage of saving human lives. Thus it spares the operatives 
 employed in this business the liability to the phosphorus 
 disease already mentioned. Again, ordinary phosphorus is 
 very poisonous ; in fact the tips of matches containing this 
 substance have not only often produced the death of children 
 
206 CHEMISTRY. 
 
 who have tasted them, but such matches have occasionally 
 been used in cases of intentional suicide. Of course, as safety 
 matches contain no phosphorus, these forms of poisoning 
 cannot arise from them. 
 
 A flame of fire, as a visible and tangible thing, has in all 
 ages been accepted as a symbol which appropriately typifies 
 enlightenment of the mind and soul. This favorite and 
 beautiful figure loses none of its fitness when narrowed in its 
 application to the aspects of these subjects in their peculiarly 
 modern forms. For in the friction match, whose cheapness 
 brings it to the hand of every human being, however low his 
 degree, we may discover the type of that opportunity for en- 
 lightenment offered to individuals whose circumstances seem 
 most humble and even forbidding. The one is the invention 
 of modern science ; the other the gift of modern laws, of 
 modern theories of the rights of men, of modern schools, 
 libraries, and newspapers, of the modern printing-press, 
 telegraph, and railroad. 
 
 READING REFERENCES. 
 Friction Matches. 
 
 Schrotter, A. v. Chem. News, xxxvi, 207, 219, 259. 
 Picaud, A. La Nature, Jan. 1888. p. 90. 
 
 (This article makes the distinct claim that the friction match was in- 
 vented in 1831, by a Frenchman named Charles Sauria.) 
 
CARBON. 
 
 207 
 
 xxiv. 
 
 CARBON. 
 
 ARBON exists in nature in a multitude of forms. 
 It is rarely found in the absolutely pure and un- 
 combined condition, though certain well-known 
 substances possess it in large quantity. 
 
 Ordinary Charcoal. 
 
 Probably the most familiar and representative form of 
 carbon is that known as charcoal. But charcoal is rarely free 
 from other chemical elements, and a distinction ought to be 
 
 FIG. 51. Charcoal pit. 
 
 made between it and the absolutely pure form of carbon. 
 Charcoal is produced by the partial decomposition of vegeta- 
 ble or animal substances under the influence of heat. Thus 
 charcoal is commonly prepared by piling wood into a conical 
 heap, then covering it with earth and sods, and finally set- 
 
208 
 
 CHEMISTRY. 
 
 ting it on fire within. Certain portions of the wood are thus 
 burned, while others are only charred. The wood is decom- 
 posed by the heat to which it is subjected ; volatile materials 
 generated by this decomposition are expelled, while there is 
 left behind a solid matter consisting mainly of carbon, and 
 called charcoal. 
 
 FIG. 52. Charcoal burners at work. 
 
 Animal Charcoal. 
 
 The same general treatment of certain animal matters, 
 such as waste leather, gives rise to a finer kind of carbon 
 called animal charcoal. 
 
 Again, when bones are partly burned they produce what 
 is called bone-coal. The mineral matter of the bone under- 
 goes no change by the heat; but the gelatinous matters 
 
CARBON. 
 
 200 
 
 which permeate it are decomposed, and they leave behind 
 them the carbon deposited upon this mineral matter. 
 
 Lamp-black. 
 
 Another material, closely assimilated to those already 
 spoken of, is lamp-black. This is a product of the imperfect 
 
 
 FIG. 53. Manufacture of lamp-black. 
 
 combustion of substances like oil, tar, resin, and the like, 
 which are very rich in carbon. The tar, or resin, being set on 
 fire is allowed to burn, but in an imperfect way, and so as to 
 evolve a dense black smoke. The smoke flows into a cham- 
 14 
 
FIG. 54. Tree trunks discovered in coal mines. 
 (210) 
 
CARBON. 
 
 211 
 
 ber prepared for it, where the sooty material collects on the 
 floor and walls. It is afterward scraped up and put, into 
 packages for commercial distribution. In the English 
 method of manufacture of lamp-black the smoke is made to 
 pass through a series of heavy canvas bags. From openings 
 at the bottoms of the bags the soot is afterward drawn out 
 for packing. 
 
 Coal. 
 
 Anthracite coal and bituminous coal are both well-known 
 compounds of carbon. Anthracite seems to be derived from 
 
 FIG. 55. Bags in which lamp-black is collected in the English process of manu- 
 facture. 
 
 bituminous coal which has been subjected in the earth to 
 heat and pressure under conditions favorable to the expulsion 
 of some of the more volatile constituents of the original 
 bituminous coal. Both of these combustibles, when care- 
 fully studied, show distinct evidences of their vegetable 
 origin. Plainly they are accumulated masses of the remains 
 of a rank vegetation which flourished in an earlier period in 
 the geological history of our globe. Careful observations 
 made in the mines have revealed in the coal the existence of 
 
212 CHEMISTRY. 
 
 trunks of trees, branches, leaves, fruits, in various conditions 
 from the one extreme of comparatively perfect preservation, 
 to the other extreme in which the mineral preserves a mere 
 impression of the original vegetable matter. These remains 
 have made it possible to construct a complete botany of this 
 period of geological history ; and with but a moderate aid of 
 the imagination artists have been able to produce ideal land- 
 scapes representing these early forms of vegetable life as 
 they flourished in the ancient ages. 
 
 Graphite. 
 
 Closely allied to anthracite coal is that valuable material 
 called graphite. This a very compact and comparatively 
 pure form of carbon. It is familiarly known to every one in 
 the black material used in lead-pencils. Graphite is com- 
 monly called black lead, though it is a well-established fact 
 that it contains none of the metal properly called lead. 
 Strangely enough, graphite is remarkably incombustible 
 under all ordinary circumstances. It is also like other 
 forms of carbon infusible even at the highest temperatures 
 known. On account of these properties graphite finds use, 
 though it must be deemed a somewhat anomalous one, in the 
 manufacture of crucibles. When the precious metals are 
 fused in such a crucible, at a high temperature in a glowing 
 furnace, an interesting paradox is furnished. It is this : the 
 coal freely burning in the fire, and so furnishing the intense 
 heat desired is fundamentally of precisely the same chemi- 
 cal nature as the graphite of the crucible, which resists the 
 heat and combustion, and, while allowing the metals to melt, 
 preserves them. 
 
 The Diamond. 
 
 The diamond is nearly pure carbon, crystallized. Perhaps 
 it is not too much to say that it is the most striking and 
 wonderful of all the forms of this interesting element. The 
 costliness of the diamond is referable largely to its great 
 
214 
 
 CHEMISTRY. 
 
 rarity ; for it is found in comparatively few portions of the 
 earth. 
 
 The ancient Greeks and Romans highly prized the rare 
 and precious crystal, which they obtained from India, and it 
 was worn by them not only because of its costliness and 
 beauty, but also because they believed that it served as a 
 
 FIG. 57." The Star of the South." Fir,. 58." The Regent " or " Pitt. 
 
 FIG. 59." The Orloff." FIG. 60." The Grand Mosul." 
 
 Great diamonds of the world (natural size). 
 
 potent charm against alarms and enchantments ; more im- 
 portant yet, they ascribed to it the power of preserving the 
 peace and harmony of the family circle. Upon this point a 
 French writer has wittily said : " Cette derniere vertu, je 
 crois qu'il la possede encore qnand le mari est assez riche 
 pour acheter le bijou que sa femme ambitionne de porter ! " 
 The East Indies, the Brazils and the Cape of Good Hope 
 may be said to be the principal sources of this gem. In Bra- 
 zil the search for diamonds is systematically conducted. The 
 
v ,&- * ^sc, 
 
 FIG. 61. -Transportation of diamonds under military protection. 
 (215) 
 
216 CHEMISTRY. 
 
 diamond-bearing soils are carefully pulverized in vessels of 
 water, under the direction of experienced inspectors. The 
 work is done by slaves who prosecute their search under the 
 stimulus of the well-understood rule that he who finds a 
 diamond weighing seventeen and one half carats, or more, 
 publicly receives his freedom as a reward. Notwithstanding 
 the systematic labor applied to the search for these gems, and 
 the fascination naturally attending undertaking's of this sort, 
 the wealth of Brazil is derived to a vastly greater extent 
 from its agricultural products than from its mines. Thus it 
 is stated that from 1740 to 1822, a period of more than 
 eighty years, the diamond mines yielded but little more than 
 $17,000,000. On the other hand, the value of coffee exported 
 in a single year has sometimes been double or even more 
 than double this amount. Thus in the year 1859 the coffee 
 exported was valued at above $28,000,000 ; and in 1873 the 
 quantity of this article exported was valued at above 
 $60,000,000. 
 
 In 1728 diamonds were discovered in Brazil, and until re- 
 cently this has been the chief source of them. But in 1868 
 a child at play on the banks of the Orange River, in South 
 Africa, picked up an attractive pebble which proved upon 
 examination to be a diamond of twenty-one and one quarter 
 carats. This accidental discovery has led to the most im- 
 portant results; for the South African mines of the great 
 Kimberly district have since yielded, in the aggregate, 
 diamonds valued, after cutting, at about five hundred mill- 
 ions of dollars. 
 
 The larger gems are always exceedingly rare. On this 
 account the money value of diamonds increases in a far more 
 rapid ratio than the weight. 
 
 The Cutting of Diamonds. 
 
 The cutting of diamonds as an art ha^s been known for but 
 a few centuries, and the perfection with which it is at present 
 conducted is of much more recent date. Of course the proc- 
 
FIG. 62. Diamond cutter at work. 
 (217) 
 
218 CHEMISTRY. 
 
 ess is an extremely delicate and important one, because it 
 involves splitting off portions of the gem so as to reduce it 
 to the exact geometrical shape previously decided upon. 
 That form called the brilliant is the one most often produced 
 
 FIG. 63 Diamond known as " The Star of the South," before and after cutting. 
 
 at the present day. The business of cutting diamonds has 
 been for a long time concentrated in the city of Amsterdam, 
 in Holland. Here, among a Jewish population of twenty- 
 eight thousand persons, ten thousand are employed exclu- 
 sively in working on diamonds. In many cases diamonds are 
 
CARBON. 
 
 210 
 
 subject to a very large relative loss of weight by the process 
 of cutting. Thus the Koh-i-noor, when brought from India 
 as a gift from the East India Company to the English Crown, 
 was in a rough state and weighed one hundred and eighty- 
 six carats; it was afterward cut in Amsterdam; it suffered a 
 
 FIG. 04. Diamond polisher at work. 
 
 loss of weight variously stated at from eighty to one hundred 
 carats. After the first trimming the gem is carefully pol- 
 ished by rubbing it gently against a revolving plate upon 
 which is a mixture of oil and diamond dust. 
 
 Up to the close of the last century the nature and compo- 
 sition of the diamond had been a subject of interesting 
 discussion among students of natural science. At the period 
 
220 CHEMISTRY. 
 
 mentioned, however, the question was settled by Lavoisier 
 and other scientific investigators, who clearly proved that 
 the diamond underwent complete combustion in oxygen and 
 that as a result carbon dioxide gas was generated. 
 
 FIG. 65. The Koh-i-noor before cutting. FIG. 66. The Koh-i-noor after cutting. 
 
 Infusibility of Carbon. 
 
 Carbon differs from most solid substances in the fact that 
 it is infusible at the highest temperature to which it has yet 
 been subjected. And since in the elementary form it has not 
 been changed to the liquid state, much less has it been 
 brought to the gaseous condition. Indeed this stability and 
 fixedness of carbon is one of its most valuable attributes. 
 Thus this characteristic is a principal one that renders it 
 specially appropriate for use in the points employed in 
 electric lighting. It is true these pencils slowly burn away. 
 But some combustion ought to be expected when it is re- 
 membered that the electric current, flowing from one pencil 
 to the other, affords an intense heat as well as brilliant 
 
CARBON. 
 
 light. But it is a general law that substances give out the 
 most intensely brilliant white light when they neither liquefy 
 nor volatilize, and to this principle exemplified both by the 
 carbon pencils of the so-called arc light and by the delicate 
 
 FIG. 67. Magnified view of the carbon terminals used for the production of the 
 electric light. 
 
 thread-like carbon loops of the incandescent electric light- 
 must be referred not only the brilliancy of the electric 
 light, but also in fact the light produced by most of our 
 illuminating materials. 
 
222 
 
 CHEMISTRY. 
 
 Decolorizing Power of Carbon. 
 
 Carbon, whether in the form of wood charcoal, animal 
 charcoal, or bone-coal, lias a wonderful power of decolor- 
 izing liquids. Even more compact carbonaceous matter, such 
 as anthracite coal, possesses this same property, though, as 
 
 might be expected, to a much 
 interior degree. Thus if a 
 colored solution is strained 
 through a considerable quan- 
 tity of one of these forms of 
 carbon, the latter substance 
 absorbs the coloring matter 
 and the liquid passes through 
 practically colorless. On ac- 
 count of this wonderful pow- 
 er bone-coal is used in the 
 arts in enormous quantity in 
 many processes where liq- 
 uids must be decolorized. 
 The sugar refining industry 
 affords a prominent example 
 upon this point. Here enor- 
 mous quantities of bone coal 
 are used for the purpose of 
 whitening the syrups before 
 crystallizing the sugar. 
 
 Charcoal has also a similar, 
 and yet more striking, prop- 
 erty of absorbing offensive 
 gases. Thus tainted meat 
 packed in freshly-burned charcoal quickly loses its odor 
 which is absorbed by the coal and the meat then becomes 
 sweet and wholesome. 
 
 Chemical Properties of Carbon. 
 
 The chemical properties of carbon are by no means less 
 wonderful than the characteristics already referred to. It is 
 
 FIG. 66. Automatic regulator whereby 
 the carbon pencils of the electric light are 
 maintained at the proper distance apart. 
 
CARBON. 
 
 223- 
 
 very inert at low temperatures ; but at high temperatures 
 it manifests chemical activities of extraordinary vigor. Thus 
 at high temperatures carbon withdraws oxygen from almost 
 every other element known, in this way manifesting chemical 
 force superior to that possessed by any of them. 
 
 Other Natural Forms of Carbon. 
 
 In addition to the well-known forms of matter containing 
 carbon, and already described, there are yet many others. 
 
 Thus it is found in the at- 
 mosphere, as has already been 
 explained, in the form of car- 
 
 bon dioxide. This gas exists 
 in the air in small relative pro- 
 portions, but in enormous ag- 
 gregate amount. 
 
 As a natural carbonaceous 
 substance, petroleum, too, 
 ought not to be forgotten. 
 This wonderful and useful 
 substance, stored up beneath 
 the surface of the earth in 
 incredibly large quantities, 
 owes its chief value to its 
 wealth of carbon. It is com- 
 posed of carbon and hydro- 
 
 gen, but the former is the im 
 
 constituent to which is refer- 
 able the beautiful light it 
 affords. 
 
 FiCr. 60. Colored liquid filtered through 
 charcoal, and thereby decolorized. 
 
 In some petroleum-producing regions, notably in the vicin- 
 ity of Pittsburg, Pa., the earth contains pockets of gaseous 
 hydrocarbons. These pockets have been pierced by boring 
 implements, and the gas, which comes out under a tremendous 
 pressure, is now utilized not only for domestic heating, but 
 also in the great manufacturing establishments of that vi- 
 cinity. 
 
- - 
 
CARBON. 225 
 
 Again, the marble and the limestones of the globe contain 
 enormous quantities of carbon. These minerals consist 
 principally of calcic carbonate (Ca CO 3 ) ; and the carbon 
 makes up about one eighth of this substance. Since some 
 whole mountain chains consist chiefly of limestone or marble 
 it is plain that the total amount of carbon in these forms 
 must be very large. 
 
 Carbon in Animal and Vegetable Substances. 
 
 With few exceptions, all animal and vegetable matters 
 contain carbon, which indeed appears to perform its most im- 
 portant offices in connection with the kingdoms of life. Thus 
 it has been called the characteristic element of animal and 
 vegetable compounds. So vast is the variety of these com- 
 pounds already recognized that it is hardly conceivable that 
 man can ever be able to acquire an acquaintance with all 
 those as yet undetected. 
 
 READING REFERENCES. 
 
 Coal, and the Coal-mines of Pennsylvania. 
 
 Harper's Magazine, xv, 451. 
 Diamonds. 
 
 Scribner's Monthly, v, 529. 
 
 Harper's Magazine, xix, 466; xxxii, 343. 
 Diamond Fields of South Africa. 
 
 Harper's Magazine, xlvi, 321. 
 Diamonds, Large. 
 
 Science, x, 69. 
 Petroleum. 
 
 Peckhani, S. F. Report on petroleum in connection with the U. S. 
 
 Census of 1880. Washington 1885. 
 15 
 
CHEMISTRY. 
 
 XXV. 
 
 COMPOUNDS OF CARBON AND OXYGEN. 
 
 1HILE compounds of carbon and hydrogen are very 
 numerous, those already known being numbered 
 by hundreds, the affinities of oxygen and carbon 
 give rise to a strikingly different result. 
 When combined with oxygen alone, carbon forms but two 
 compounds. These are expressed by the following names 
 and formulas : 
 
 Carbon monoxide, CO. Carbon dioxide, C0 2 . 
 
 Carbon Monoxide (CO). 
 
 This gas is most familiarly known as that one which often 
 plays upon the surface of a hard coal fire and burns there 
 with a dark blue, feebly luminous, flame. Most of the phe- 
 nomena of its production and final burning may be presented 
 as follows : When an ordinary coal fire, burning in a stove, 
 is amply supplied with air at the bottom, the oxygen of the 
 air burns the lower portions of carbon into carbon dioxide. 
 Next, this carbon dioxide is carried up, by the draft, between 
 any masses of fresh coal that may be upon the top of the 
 fire. This fresh coal has itself affinity for oxygen under the 
 circumstances just described as prevailing. As a result, each 
 molecule of carbon dioxide from the lower portion of the 
 fire yields one of its atoms of oxygen to an atom of carbon 
 in the upper part. 
 
 The chemical change is represented by the following equa- 
 tion : 
 
 CO 2 + C 2CO 
 
 One molecule of One atom of Two molecules of 
 
 Carbon dioxide, Carbon, Carbon monoxide, 
 
 44 12 56 
 
 parts by weight. parts by weight. parts by weight. 
 
 56 56 
 
COMPOUNDS OF CARBON AND OXYGEN. 227 
 
 . .- . . * 
 
 As a result, therefore, carbon monoxide is formed, and es- 
 capes as a colorless gas from the top of the fuel ; there, if 
 the upper door of the stove admits a sufficient amount of air, 
 the carbon monoxide combines with the oxygen of this air, 
 and burns with the blue flame already referred to, and so 
 produces carbon dioxide again. 
 
 This chemical change is represented by the following 
 equation : 
 
 2CO + O 2 2CO 2 
 
 Two molecules of One molecule of Two molecules of 
 
 Carbon monoxide, Oxygen, Carbon dioxide, 
 
 56 32 88 
 
 parts by weight. parts by weight. parts by weight. 
 
 88 88 
 
 The carbon monoxide is a very poisonous gas, far more in- 
 jurious to health than carbon dioxide. 
 
 Carbon Dioxide (CO 2 ). 
 
 This substance and its manner of production have been 
 referred to more than once in preceding chapters. A some- 
 what more extended notice of it, however, is appropriate to 
 this place. 
 
 It has already been stated that carbon dioxide exists ready- 
 formed in nature notably in the atmospheric air. Its prin- 
 cipal natural source in the atmosphere is the combustion of 
 fuel ; for almost all fuel is carbonaceous. Thus coal, wood, 
 oil, illuminating gases, are all highly carbonaceous substances, 
 and one of the principal products of their combustion is the 
 gas now under consideration. 
 
 As has already been described, the respiration of animals 
 is closely connected with a real combustion in the living 
 being. It is true that this sort of combustion is not attended 
 by the evolution of light ;' it is productive of heat, neverthe- 
 less, and the heat afforded by respiration is an important fac- 
 tor in the sustenance of animal existence. For this heat not 
 only enables the living being to endure the chilling effects of 
 
CHEMISTRY. 
 
 the winter's cold ; it also keeps the temperature of the in- 
 ternal organs up to that point which is necessary for the 
 proper performance of certain animal functions of which 
 digestion is a most important example. Now by this com- 
 bustion carbon dioxide is generated just as truly as would be 
 
 FIG. 71. Production of carbon dioxide by combustion of a diamond in oxygen gas. 
 
 the case if the flesh of the living animal were consumed in a 
 glowing fire. The product of respiratory combustion is the 
 same carbon dioxide as that recognized in well-defined burn- 
 ings. The quantities of carbon dioxide evolved by man 
 and certain of the domestic animals, in each hour of their 
 existence, have been calculated. They are approximately 
 Stated in the following table : 
 
COMPOUNDS Off (JAR&6N AND OXY&EN. 220 
 
 A man exhales 4 gallons carbon dioxide per hour. 
 A dog " 4i " " " " 
 
 A horse " 50 " " " " " 
 
 An ox " 70 ' " " " " 
 
 And M. Boussingault has calculated that the approximate 
 amount of carbon dioxide produced in the city of Paris dur- 
 ing a single twenty-four hours is as follows : 
 
 Amount produced by living animals 55,000,000 cubic feet. 
 
 Amount produced by burning of various kinds 
 
 of fuel 27,000,000 cubic feet. 
 
 Total C0 2 produced in twenty-four hours, 82,000,000 cubic feet. 
 
 There are certain other natural sources of carbon dioxide 
 that are worthy of passing mention. Thus in many parts of 
 the world the gas is continually evolved not only from active 
 volcanoes, but also from extinct ones. Again, another inter- 
 esting source though not in the aggregate a very impor- 
 tant one is found in natural mineral springs. In these the 
 water often comes to the surface highly charged with carbon 
 dioxide, and the gas, escaping into the air, imparts to the 
 water its well-known bubbling appearance. (See pp. 139, 142.) 
 
 Experiments with Carbon Dioxide. 
 
 For chemical purposes carbon dioxide is commonly pro- 
 duced by the action of an acid upon some one of the salts 
 known as carbonates. Accordingly hydrochloric acid and 
 calcic carbonate (that is, common marble) when brought to- 
 gether produce carbon dioxide. This fact may be readily 
 shown by the performance of a simple but interesting ex- 
 periment. The operation may also serve for the display of 
 some of the principal properties of the gas. 
 
 The experiment in question may be conducted advantage- 
 ously somewhat as follows : Provide two convenient glass 
 jars such as candy jars or preserve jars ; also a short candle, 
 a piece of copper wire, a bottle of hydrochloric acid and some 
 fragments of white marble. Now attach the candle to the 
 
330 CHEMISTRY. 
 
 wire and after lighting the former let it down. into the jars, 
 still burning. The combustion continues because the jars are 
 full of air and contain ample quantities of oxygen. Next 
 withdraw the candle and extinguish it for a moment. Now 
 place in the bottom of the larger jar some hydrochloric acid 
 and into it gently drop some of the fragments of marble. 
 Effervescence immediately commences. A careful examina- 
 tion of effervescence shows that in this, as in other cases, the 
 process consists in the evolution of a gas from a liquid. In 
 the case in question a colorless gas is plainly evolved, and 
 this gas is carbon dioxide. 
 
 The chemical change is represented by the following 
 equation : 
 
 CaCO 3 -f 2HC1 
 
 CO 2 -f CaCl 2 
 
 -f H 2 
 
 One molecule of 
 
 Two molecules of 
 
 One molecule of 
 
 One molecule of 
 
 One molecule of 
 
 Calcic carbon- 
 
 Hydrochloric 
 
 Carbon 
 
 Calcic 
 
 Water, 
 
 ate, 
 
 acid, 
 
 dioxide, 
 
 chloride, 
 
 
 100 
 
 73 
 
 44 
 
 111 
 
 18 
 
 parts by weight. 
 
 parts by weight. 
 
 parts by weight. 
 
 parts by weight. 
 
 parts by weight. 
 
 173 173 
 
 After allowing the effervescence to continue for five or 
 ten minutes, relight the candle and again lower it into the 
 jar now containing carbon dioxide. If a sufficient quantity 
 of the gas is present, the light will be promptly extinguished 
 when the wick passes below the surface of the gas. The ex- 
 periment displays at this stage the additional fact that the 
 carbon dioxide is heavy, and in filling the jar it does so from 
 the bottom upward. Now relight the candle and immerse it 
 in the second jar ; this is proved to contain air by the fact 
 that the candle continues to burn. While it is still quietly 
 burning there, pour gently upon it the carbon dioxide accu- 
 mulated in the other jar. If the amount of this gas is large 
 enough, it will fill the jar containing the lighted candle and 
 so will readily extinguish the latter. 
 
 These experiments demonstrate simply and clearly, certain 
 of the most important properties of carbon dioxide. Its 
 
COMPOUNDS OP C ARSON AND OXYGEtf. 231 
 
 action in extinguishing flame is to quench it, very much as 
 water would. When the candle dips beneath the surface of 
 the carbon dioxide, the flame expires simply from lack of that 
 oxygen of the air which ordinarily supports the combustion. 
 And this leads very naturally to the additional statement that, 
 in similar fashion, living beings are drowned if immersed 
 in carbon dioxide. For just as water prevents the access 
 of air to the lungs, and then drowning ensues, so when the 
 animal is beneath the surface of carbon dioxide he dies 
 because the heavy gas acts as an effectual barrier to the 
 access of air. 
 
 Effervescing Beverages. 
 
 A large quantity of carbon dioxide taken into the lungs is 
 promptly fatal to animal life ; even a small increase of that 
 gas, in the atmospheric air breathed, produces a marked low- 
 ering of the vitality. It is an interesting fact, however, that 
 when this gas is taken into the stomach, especially in its 
 solution in water, it has a wholesome and stimulating effect. 
 
 When carbon dioxide is dissolved in water it seems to pro- 
 duce a true acid, though an unstable one. In accordance 
 with the present nomenclature, this acid is called carbonic 
 acid and is represented by formula H 2 CO 3 . This substance 
 is present as the main constituent, or as a subordinate one, 
 in certain natural mineral waters, and in many simple effer- 
 vescent beverages. Thus plain soda-water is merely a so- 
 lution of carbon dioxide in water. Such solutions are now 
 manufactured on a large scale, and by mechanical appliances 
 are filled into siphon-like bottles in such a way that small 
 quantities of the liquid may be withdrawn without loss of the 
 principal stock of gas. 
 
232 CHEMISTRY. 
 
 XXVI. 
 
 ORGANIC CHEMISTRY. 
 
 [HEMISTS long ago recognized certain differences 
 between the substances found in distinctly ani- 
 mal and vegetable matters, on the one hand, and 
 the substances found in mineral mutters, on the 
 other; between those things which constitute organisms 
 like animals and plants, as compared with those of non-living 
 substances like clay, iron-rust, alum, saltpetre, etc. 
 
 Animal matters and vegetable matters are the products of 
 bodies possessing organs. Organs are parts having specific 
 functions. Thus the stomach is an organ possessing the 
 function of digestion, and the lungs are organs possessing the 
 function of respiration. Again, the leaves, the flowers, the 
 seeds, the roots, of plants, are separate organs, and they 
 possess special and very different functions of the living 
 vegetable to which they belong. Accordingly, substances 
 derived from vegetables and animals are called organic. 
 Non-living objects, as rocks and other mineral and earthy 
 substances, do not possess organs, and they have long been 
 called inorganic. 
 
 This division of matters into organic and inorganic was for- 
 merly thought an essential one ; it is not now considered so. 
 It is now known that the chemical changes of living animals 
 and plants are governed by the same laws as those prevailing 
 in the changes of rocks and other lifeless forms of matter. 
 
 Grounds for Dividing Chemistry into Two Great 
 Departments. 
 
 Chemistry is still, however, commonly divided into the two 
 great departments inorganic chemistry and organic chemis- 
 try ; but this division is recognized as a matter of con- 
 venience mainly. 
 
ORGANIC CHEMISTRY. 233 
 
 Three reasons which may be mentioned, why the dis- 
 tinction is still maintained, are : 
 
 First. The number of organic compounds is very great. 
 
 Second. These compounds perform varied and important 
 offices in connection with human beings in their growth and 
 nourishment in health, and in their treatment in illness. The 
 importance which they assume is increased by the relations of 
 the lower animals and the individuals of the vegetable king- 
 dom to man. 
 
 Third. As will appear hereafter, the processes of analysis 
 and methods of investigation in organic compounds are 
 slightly different, as a whole, from those that .serve for the 
 study of inorganic. 
 
 Definition of Organic Chemistry. 
 
 The inorganic and the organic worlds are, however, so 
 closely allied in some respects, and certain of the substances 
 of the one have such close and natural affiliations with 
 those of the other, that indeed it is often found difficult to 
 determine where shall be placed the line of demarkation 
 between these two great natural groups. In fact, chemists 
 have not found the definition incidentally introduced in the 
 preceding paragraph sufficiently distinct. To make it more 
 so, organic chemistry has been sometimes called the chemis- 
 try of the carbon compounds. It has sometimes been called 
 the chemistry of the hydrocarbons. Again, the following still 
 more rigid and scientific statement is often employed : 
 organic chemistry includes those compounds in which the 
 atoms of carbon are directly united either icith other atoms of 
 carbon, or with atoms of hydrogen, or with atoms of nitrogen. 
 
 Two Classes of Organic Compounds. 
 
 There is one distinction between the classes of organic 
 compounds themselves that ought not to be omitted here. 
 The members of the organic family differ very much in their 
 properties, according as they are crystalline or cellular. 
 Crystalline organic compounds, of which cane sugar may be 
 
234 CHEMISTRY. 
 
 taken as a familiar and suitable example, are numerous. 
 These compounds are closely allied in some respects to inor- 
 ganic compounds. They do not seem to have so close a re- 
 lation to the vital processes as might at first be supposed. 
 But those organic compounds that are cellular, such, for ex- 
 ample, as the fibre of wood and the fibre of lean meat, are 
 much removed from inorganic bodies, and seem to bear a 
 peculiar and close relation to the vital forces. 
 
 The Great Number of Organic Compounds. 
 
 The vast number of organic compounds is referable to at 
 least four fundamental principles : 
 
 First. The chief element, carbon, has a large number of 
 points of attraction that is, four; on this account it is capable 
 of attaching to itself by chemical affinity many other atoms. 
 
 Second. Carbon atoms are capable of uniting together in 
 chains of great length and variety of arrangement. Two 
 methods of arrangement are especially noteworthy ; the one 
 method is that where the chains are open that is, not at- 
 tached at the ends. The other arrangement is that where 
 the chains are closed, the series of atoms of carbon making 
 a circuit. An appropriate example of this style of union is 
 found in the benzol ring or the benzol hexagon. 
 
 The open chain may be conveniently represented by the 
 left-hand diagram below, and the closed chain, the benzol 
 ring, is often represented by the right-hand diagram below. 
 
 ^ 
 
 ~ G - -C* ^C- 
 
 ~~ ( ?~~ G C 
 
 x c 
 
 I 
 
 Third. One of the most interesting and important features 
 of organic compounds is that in them certain elements may 
 
ORGANIC CHEMISTRY. 235 
 
 stay together for a considerable time in comparatively per- 
 manent groups which act like elements. Such groups of 
 atoms are called compound radicles. 
 
 Fourth. It is now distinctly recognized that a given organic 
 compound, possessing a certain distinct set of properties, may 
 have its atoms undergo a rearrangement without any increase 
 in the number of them or any change in their kinds or rela- 
 tive proportions. 
 
 Some organic substances have molecules capable of several 
 different rearrangements, such that different compounds may 
 be produced. Thus Professor Cayley has computed that a 
 compound of the paraffin group containing four carbon atoms 
 is capable of two rearrangements within the molecule ; but a 
 compound of this group containing thirteen carbon atoms is 
 capable of as many as seven hundred and ninety-nine dif- 
 ferent rearrangements of its atoms.* This property of or- 
 ganic compounds is called isomerism. 
 
 Organic Radicles Act like Elements. 
 
 It has already been pointed out that the seventy recognized 
 elements are capable of interaction and combination to pro- 
 duce a vast number of compounds. 
 
 Now the compound radicles of organic chemistry, espe- 
 cially the hydrocarbons, act like so many more elements, 
 and, being themselves far more numerous than the true 
 elements, these compound radicles afford the material which 
 may be combined into yet larger numbers of substances than 
 those recognized among inorganic matter. 
 
 The inorganic compounds have been arranged in a certain 
 order in accordance with their natural affiliations, and though 
 when such arrangement is made some gaps appear, these 
 gaps are of great service in that they suggest that many 
 more compounds than those yet recognized or described may 
 be hereafter produced. 
 
 * Cayley, *' On the analytical forms called trees, with applications, the theory of chem- 
 ical combinations." Brit. Assoc. Rep. 1875, 257. Recalculated by Dr. Hermann, of 
 Wurtzburg. (Referred to in Roscoe & Schorlemmer's Chemistry, vol. iii. Part I. p. 122). 
 
236 CHEMISTRY. 
 
 To the organic compounds the same statement may be 
 applied. Gaps in their list point out an avenue for future 
 discovery in organic chemistry. 
 
 Organic Compounds Classified. 
 
 The difficulty of classifying organic compounds is of course 
 very great. This is due j /t>^, to their great number; second, 
 to the many relationships of one and the same substance; 
 third, to the relative imperfection of our acquaintance with 
 the most of them. Those substances with which chemists 
 are best acquainted are arranged for discussion in many dif- 
 ferent ways. The following outlines will serve to indicate 
 the form in which the subject is briefly presented in this 
 chapter : 
 
 First. The great group of substances derived from marsh 
 gas, and called, in general, the open-chains or paraffin or 
 fatty series. 
 
 Second. The great group of substances derived most di- 
 rectly from benzol, and called in general the closed-chain or 
 aromatic series. 
 
 Third. Other less easily classified vegetable matters. 
 
 Fourth. Other less easily classified animal matters. 
 
 Sub-Chapter I. The Fatty Series. 
 This great group includes many compounds of both practi- 
 cal and theoretical interest. They are best understood by a 
 tabular statement based on what is called type-compounds. 
 This may be presented as follows (these types moreover 
 serve also for the aromatic series, with slight modifications) : 
 
 Types of Organic Compounds, 
 ist Type, H H, The Hydrogen-gas Type. 
 
 The general formula is R R. 
 
 + 
 
 R represents one molecule of an electro-positive radicle. 
 
ORGANIC CHEMISTRY. 237 
 
 It may be either simple or compound. When compound, it 
 is usually made up of carbon and hydrogen. 
 
 R represents one molecule of an electro-negative radicle. 
 It may be either simple or compound. When compound, it 
 is usually made up of carbon, hydrogen and oxygen. 
 
 EXAMPLES. 
 
 C+ + 
 R R Positive radicle CH 3 CH 3 Methyl, 
 
 1 R R Negative radicle C 2 H 3 C 2 H 3 Acetyl, 
 
 I R R Ketone- CH 3 C 2 H 3 or 0=C=(CH 3 ) 2 Ordinary acetone 
 
 (methyl-acetyl). 
 
 R H Hydride CH 3 H Methyl hydride (marsh-gas), 
 R H Aldehyd C 2 H 3 H Acetic aldehyd, 
 
 R 1 C 2 H 5 Cl Etliyl chloride, 
 
 (Halogen substitution compound) 
 R Cl C 2 H 3 Cl Acetyl-chloride. 
 
 2d Type, H 2 O, or H O H, The Water Type. 
 
 The general formula is R D K. D represents one atom 
 of a linking dyad. It is usually oxygen. 
 M represents one atom of a monad metal. 
 
 EXAMPLES. 
 
 -f 4- 
 
 R R Simple ether C 2 H 5 C 2 H 5 Ethylic ether, 
 
 + + 
 
 R R Mixed ether CH 3 C 2 H 5 Methyl-ethyl-ether, 
 
 R R Anhydride C 2 H 3 C 2 H 3 Acetic anhydride, 
 
 + 
 
 R R Compound ether C 2 FT 5 C 2 H 3 Ethyl-acetic ether, 
 
 R_O H Alcohol C 2 H 6 H Ethyl alcohol, 
 
 + 
 
 R S H Mercaptan C 2 H 5 S H Ethyl sulpho-hydrate, 
 
 R Se H Seleno-mercaptan C 2 H 6 Se H Ethyl seleno-hydrate, 
 H R~ Acid H C 2 H 3 Acetic acid, 
 
 M Salt Na Cj,H 3 Sodic acetate. 
 
238 
 
 CHEMISTRY. 
 
 R N=: 
 
 3d Type, H 3 N, The Ammonia-gas Type. 
 EXAMPLES. 
 
 I 3 Amine C 2 H 5 N=H 3 Ethyl-amine, 
 
 (CH 3 ) 3 As Tri-methyl-arsine, 
 (C 2 H 5 ) 3 Sb Tri-ethyl-stibine, 
 C 2 H 5 P=H 2 Ethyl-phosphine, 
 
 R As=H 3 Arsine 
 
 + 
 
 R Sb=H 2 Stibine 
 
 + 
 
 R P=H 2 Phosphino 
 
 =H 2 Amide 
 
 _ 
 
 Ztr Alkalamide, C 3 H 6 NZH 
 
 C 2 H 3 N=H 2 Acet-amide, 
 C 2 H 3 
 
 Ethyl-acet-amide, 
 
 TT7-0-H 
 
 
 R'' ;i Amic acid (CO)" Carbamic acid. 
 
 i> = r! 2 IN = r! 2 
 
 + ^v 
 
 R 4 _ N Cl Ammonium subs, comps. (C 2 H 5 ) 4 ^N 01 Ethyl-ammonium 
 
 chloride, 
 4- : v 
 
 R 4 _ P 01 Phosphon him subs, comps. (CH 3 ) 4 =P 01 Tetra-methyl plios- 
 
 phonium chloride. 
 + v 
 
 R 4 =As 01 Arsonium substitution compounds. 
 + =v 
 R 4 z=rSb 01 Stibonium substitution compounds. 
 
 A few of the compounds of carbon with hydrogen are pre- 
 sented in the following table. They represent mere starting- 
 points, so to speak, of an immense number of derivatives. 
 
 Parafins. 
 
 Olefines. 
 
 Acetylenes. 
 
 Methane CH 4 
 
 
 
 Ethane, 2 H 6 
 
 Ethylene, C 2 H 4 
 
 Acetylene, C 2 H 2 
 
 Propane, C 3 H 8 
 
 Propylene, C 3 H 6 
 
 Allylene, C 3 H 4 
 
 Butane, C 4 H 10 
 
 j Butylene, C 4 H 8 ) 
 t Tsobutylene, C 4 H 8 J 
 
 Crotonylene. C 4 H 6 
 
 Pentane, C 5 H 12 
 
 j Pentylene, C 5 H 10 ) 
 I Amylene, C 5 H 10 J 
 
 Yalerylene, C B H 8 
 
 Hexane, C 6 H M 
 
 Hexylene, C 6 H, 2 
 
 Hexoylene, C 6 Hi 
 
 Heptane, C 7 H 16 
 
 j Heptylene, C 7 H 14 ) 
 I Isoheptylene, C 7 H 14 j" 
 
 Oenanthylidene, C 7 Hi 2 
 
 Marsh gas is found in water in swampy places, where, 
 under the influence of heat and moisture, vegetable matters 
 are undergoing decomposition. The gas rises in bubbles 
 
ORGANIC CHEMISTRY. 239 
 
 which are capable of taking fire from a lighted match. It 
 has been analyzed and found to have the composition H 4 C, 
 already stated. 
 
 By the replacement of its hydrogen atoms, wholly or partly, 
 by other atoms or radicles, the carbon compounds of the 
 fatty series are produced. 
 
 The hydrocarbons of this series have their most striking 
 natural source in petroleum, an oil flowing from the earth by 
 natural or artificial openings, especially in certain parts of 
 America, Europe and Asia. 
 
 The hydrocarbons of this (and other) series are artificially 
 produced from coal in the manufacture of illuminating gas, 
 a chemical industry which is discussed more at length in a 
 later chapter. 
 
 Chloroform is produced when bleaching powder is warmed 
 with ordinary alcohol (called ethyl alcohol). The substance 
 has a sweetish odor and has the remarkable though well- 
 known property of producing insensibility to pain. Owing, 
 however, to the danger of death from overdose, chloroform 
 is going out of use as an anaesthetic ether, ethyl ether, which 
 is much safer, replacing it. The chemical formula of chloro- 
 form (CH C1 3 ) at once reveals its chemical relationship to 
 marsh gas (CH 4 ). 
 
 Compounds of Carbon, Hydrogen and Oxygen. 
 
 In the table already given reference has been made to alco- 
 hols, ethers, aldehydes, and acids. Each of these terms, at 
 first applying to a special substance, is now applied to a class 
 of substances. Thus there are many alcohols; there are many 
 ethers ; there are many aldehydes ; there are many acids. 
 
 A volatile liquid called wood alcohol (methyl alcohol) is pro- 
 duced when wood is heated in closed vessels which do not 
 permit it to burn. It is found to be in fact related to 
 methane; thence it is called methyl alcohol, and to it is 
 assigned the formula CH 3 OH. It is viewed as methane, or 
 marsh gas (CH 4 ), which has had the radicle OH substituted 
 for one of the orignal atoms of hydrogen. It is also looked 
 
240 
 
 CHEMISTRY. 
 
 upon as formed after the water type. From this point of 
 view it is viewed as water (H-O-H) in which one of the 
 hydrogen atoms has been replaced by the compound radicle 
 methyl (CH 3 ) producing the substance expressible, as before 
 stated, by the formula CH 3 OH. 
 
 The following diagrams illustrate this statement : 
 
 Marsh gas. 
 
 Methyl alcohol. 
 
 Methyl alcohol. 
 
 Water. 
 
 rH 
 
 f H 
 
 CH 3 . 
 
 H 
 
 1 
 
 c -H 
 
 1 H 
 
 
 
 
 
 ] H 
 l-H 
 
 L~(OH) 
 
 II 
 
 A 
 
 It has long been known that the sugary juices extracted 
 from many vegetable matters are capable of a peculiar change 
 called alcoholic fermentation, by which there is produced 
 from the sugar a new substance called alcohol (more strictly 
 speaking, ethyl alcohol). It is a highly combustible sub- 
 stance, burning in the air with a blue flame ; when taken into 
 the stomach it produces well-recognized stimulating and 
 even terribly-intoxicating effects. Analysis has shown it to 
 possess the composition expressed by the formula C 2 H 5 OH. 
 It may be viewed as ethane (C 2 H 5 H) in which one atom of 
 hydrogen has been replaced by the radicle O H. It is also 
 viewed as formed after the water type that is, it may be 
 looked upon as water (H-O-H) in which one hydrogen atom 
 is replaced by the compound radicle (C 2 H 5 ). 
 
 The following diagrams illustrate this statement : 
 
 Ethane. 
 
 Ethyl alcohol. 
 
 Ethyl alcohol. 
 
 Water. 
 
 f=H 
 
 
 -H 
 
 (C, H 5 ) 
 
 H 
 
 C 1 H 
 C 1 H 
 
 O 
 
 -H 
 -H 
 
 A 
 
 1 
 O 
 I 
 
 -H 
 
 
 H 
 
 jj 
 
 H 
 
 l-H 
 
 I -(OH) 
 
 
 
ORGANIC CHEMISTRY. 241 
 
 Among the organic compounds recognized as composed of 
 carbon, oxygen, and hydrogen, there are the important groups 
 called carbohydrates, including glucose, cane sugar, and woody 
 fibre, also called cellulose. 
 
 Under each head are well-known substances, most of them 
 valuable as food. From this, of course, should be excluded 
 woody fibre, or cellulose, although the cellulose group in- 
 cludes some of the most important food materials, chief 
 among which is starcli. Starch occurs in slightly different 
 forms in most vegetable seeds and grains. This statement 
 carefully examined shows that starch is one of the most 
 important constituents of the food of man as well as of the 
 lower animals. The millions of inhabitants of China and 
 India live largely upon rice, whose most abundant constituent 
 is starch. Western nations consume for food vast quantities 
 of wheat flour, Indian meal and potatoes, all of which contain 
 large quantities of starch. 
 
 It is a matter of common observation that when the alcoholic 
 fermentation has proceeded some time it is liable to be fol- 
 lowed by a somewhat different kind of fermentation, attended 
 by souring. 
 
 Vinegar is produced from cider and w r ine in this way; 
 vinegar contains a peculiar acid called acetic acid ; nnd just 
 as ethyl alcohol is produced from cane sugar by alcoholic fer- 
 mentation so acetic acid, is produced from ethyl alcohol by 
 acetous fermentation. Acetic acid is found to be expressible 
 by the formula (C 2 H 3 O) O II. 
 
 Acetic acid is, however, only one member of an extensive 
 group of organic acids. Some of them, however, are very 
 different from vinegar in their properties; thus oleic, palmitic 
 and stearic acids occur in combination with glycerin in most 
 ordinary fats. When separated from the glycerin they are 
 truQ acids, even though they do not manifest that sourness 
 which is the ordinary characteristic of acids. 
 
 Ethers and aldehydes are organic compounds producible by 
 certain transformations of alcohol and acids. 
 
 The four great classes of compounds of carbon containing 
 16 
 
242 CHEMISTRY. 
 
 oxygen and hydrogen just touched upon have many repre- 
 sentatives derived from the many hydrocarbons of the paraf- 
 fin series ; but it would be out of place to attempt any further 
 discussion here. 
 
 Sub-Chapter II. The Aromatic Series. 
 
 This interesting series includes compounds grouped as sug- 
 gested by the table in Sub-Chapter I. that is, it includes 
 hydrocarbons like benzol C 6 II 6 (see p. 249), alcohols like 
 phenyl alcohol (C 6 H 6 OH, commonly known as carbolic acid), 
 while its nitrogen series is represented by phenylamine 
 (C e H 6 NH 3 commonly called aniline) which is the starting- 
 point of the aniline colors. 
 
 Napthalene, turpentine and other terpenes, belong to this 
 general series. 
 
 Sub-Chapter III. Other Vegetable Matters. 
 In the vegetable world chemists recognize a great number 
 of interesting substances not capable of so easy a reference 
 to the type compounds, or, indeed, to any clearly-defined 
 chemical position. That they are important, however, ap- 
 pears from the mere mention of such alkaloids as nicotin of 
 tobacco, caffeine of coffee, theine of tea, morphine of opium, 
 quinine of Peruvian bark, and strychnine of the nux vomica 
 bean, to which might be added many other, both allied and 
 not associated, vegetable matters. 
 
 Sub-Chapter IV. Animal Matters. 
 
 The groups of compounds referred to in the preceding 
 paragraphs gradually rise in the scale of complexity. Yet 
 there is a vast group of animal compounds containing vary- 
 ing amounts of the elementary substances, carbon, hydrogen, 
 oxygen, nitrogen, sulphur and phosphorus sometimes all at 
 once in the same molecule. Of course these are still more 
 complex. Among them may be mentioned the albuminous 
 matters occurring in blood and white of egg, the casein of 
 
ORGANIC CHEMISTRY. 243 
 
 milk, gelatins, fibrins, and even substances found in the brain 
 and nerves, like cerebrin and lecithin. 
 
 Chemists feel certain, however, that the number known is 
 an exceedingly insignificant fraction of those existing in 
 animal and vegetable substances. 
 
 Hundreds of observers and investigators have devoted in 
 the aggregate an enormous amount of study to the carbon 
 compounds. At the present day the study of the c;irbon com- 
 pounds is the chief business of chemists; indeed, the present 
 may be designated as the era of organic chemistry. Yet the 
 subject is so difficult that even professional chemists are yet 
 in a condition that perhaps ought to be designated as, rela- 
 tively, one of extreme ignorance of the chemistry of animal 
 and vegetable substances. 
 
 They are undoubtedly making great strides in advance, 
 but the progress thus far made seems to have as its chief 
 result the revealing of the world-wide field yet to be criti- 
 ically explored. 
 
244 CHEMISTRY. 
 
 XXVII. 
 
 ILLUMINATING GAS. 
 
 T is manifest, from what has been said, that in a 
 book like the present it is impossible to give any 
 considerable discussion of the vast field offered 
 by the organic compounds of carbon. It seems 
 better to choose for description some important manufactur- 
 ing operation that involves these compounds, and that is on 
 other accounts specially instructive. Accordingly the manu- 
 facture of illuminating gas is selected for consideration here. 
 
 The Manufacture of Illuminating Gas. 
 
 The material on which this industry is based is bituminous 
 coal. This substance is clearly a vegetable product, though 
 it is derived from a vegetation which lived, flourished and 
 decayed in a period of pre-historic antiquity. 
 
 The manufacture of illuminating gas, although one of the 
 most important of the chemical industries of to-day, had its 
 beginning but little before the opening of the present century. 
 A Scotchman named William Murdoch is generally credited 
 with the first introduction, into considerable use, of burning 
 gas made from coal. In 1798 lie gained the opportunity to 
 introduce his method of illumination into the engine-works 
 of Boulton & Watt, located at Soho, near Birmingham. From 
 that date the manufacture and use of illuminating gas from 
 soft coal has extended and expanded until it has reached its 
 present enormous development. 
 
 General Principles of the Process. 
 
 The general principle of the manufacture is exceedingly 
 simple. Its commercial growth, however, has been assisted 
 by the invention and application of a multitude of delicate 
 and ingenious appliances. 
 
ILLUMINATING GAS. 
 
 245 
 
 If any person will take a glass test-tube, place in it a few 
 fragments of starch, and will then heat the starch strongly 
 over a lamp flame, he will readily detect three important 
 effects. The first is that a mass oi smoky gas or vapor pours 
 out of the mouth of the 'test-tube. The second is that an 
 oily or tarry liquid condenses, on the inside of the tube, and 
 runs down in streams. The third is that at the close of the 
 operation a mass of carbon remains in the bottom of the tube 
 where the starch was. Now the various substances that have 
 been referred to as produced by the heating process are ref- 
 erable to the decomposition of the molecules of starch. 
 
 Fin. 72. Three views of a gas retort. 
 
 A Similar Operation on a Large Scale. 
 
 In the manufacture of illuminating gas on a large scale 
 there are developed practically the same series of phenomena 
 as those noted in the experiment with starch just referred to. 
 
 In the manufacture of illuminating gas, instead of starch, 
 as just described, soft coal or bituminous coal is used. 
 
 In place of a lamp a row of large furnaces is employed to 
 supply the heat. 
 
 Instead of glass tubes those of earthenware, ten or twelve 
 feet in length and between one and two feet in diameter, are 
 used. These tubes, called retorts, are placed in a horizontal 
 
246 
 
 CHEMISTRY. 
 
 position and so that the flame of the fire in the furnace may 
 sweep around them and raise them to a cherry-red heat. At 
 the front end of the retort is attached a door to prevent the 
 escape of the gases generated, and there is also a suitable 
 pipe to carry these gases forward to those other portions of 
 the works which serve to perform upon the crude gas cer- 
 tain necessary purifications; these are, first, the condensation 
 of condensable vapors; second, the removal of objectionable 
 gases. 
 
 The operations spoken of show that the gas must be carried 
 from one portion of the establishment to another. Now illu- 
 
 p IG 73. Section showing five retorts in place. 
 
 minating gas is made up of material substances, and, although 
 lighter than air, yet they distinctly possess weight. Gas will 
 not move of itself; to carry it from place to place the appli- 
 cation of force by means of mechanical appliances is requisite. 
 In fact, it is discovered that what is called an exhauster is 
 necessary for use in gas-works. The exhauster is simply a 
 kind of rotary pump which pulls the gas from the retorts in 
 which it is first formed, and pushes it along through the vari- 
 ous purifiers, to the gas-holder in which it is stored. If the 
 
ILLUMINATING GAS. 247 
 
 exhauster were not used there would be a constant tendency 
 to the creation of pressure in the retort, by virtue of which 
 the gas would penetrate the earthenware into the fire, and so 
 become a source of loss. 
 
 From what has been said it will be easily comprehended 
 that the essential parts of a gas-works are the following : 
 
 First. The furnace. 
 
 Second. The retorts, in which the coal is heated. 
 
 Third. The hydraulic main; a trough of water in which the 
 gas is cooled, and which also serves as a gate, through which 
 the gas can pass forward toward the purifiers, but not back- 
 ward toward the retort. 
 
 Fourth. The out-door condensers, in which the gas is cooled 
 and some of its vapors condense to tarry liquids. 
 
 Fifth. The scrubber, in which the gas is cleansed by a 
 spray of water. 
 
 Sixth. The purifiers, where sulphuretted hydrogen, and 
 some other objectionable gases are removed. 
 
 Seventh. The gas holder, in which the finished gas is col- 
 lected and stored prior to delivery to consumers. 
 
 The processes by which these various appliances are used 
 in the manufacture of illuminating gas may be briefly 
 sketched as follows: 
 
 A suitable quantity of soft coal is placed in an even layer 
 on the bottom of the retort. Gas at once forms and streams 
 out of the open door. The door of the retort being now 
 quickly closed by the workman the gas passes out through 
 an exit pipe called the dip-pipe, because it dips into the 
 water of the hydraulic main. The gas bubbles up from the 
 dip-pipe through the water. Once delivered in the hydraulic 
 main, the gas cannot go back to the retort. 
 
 Next, the gas passes through the condensers, a series of 
 connected up-and-down pipes. As these condensers stand in 
 the open air they cool the gas so that it deposits tarry liquids 
 that, until this stage, have been suspended in it in the form 
 of vapor. 
 
 Next the gas flows to a large iron box, called the scrubber. 
 
248 CHEMISTRY. 
 
 In different works the scrubber varies considerably in out- 
 ward shape and internal arrangements. Its essential office 
 however is to wash the gas, and it does so by the use of 
 water which is applied to the gas either in sprays or thin 
 films. Ammonia gas is the principal substance absorbed by 
 the water in the scrubber. Indeed the liquor thus produced 
 is the main commercial source, at the present day, of am- 
 monia and its compounds. 
 
 The gas next goes to the purifiers. These are large iron 
 boxes supplied with a multitude of shelves upon which, in 
 most works, dry quicklime is spread. The quicklime absorbs 
 sulphuretted hydrogen and some other acid gases. From 
 these purifiers the gas is carried on to the gas holder. 
 
 The Distillation of Coal, Chemically Considered. 
 
 Under the influence of the high temperature of the gas 
 furnace the soft coal in the retorts undergoes decomposition. 
 As has before been intimated, three distinct classes of sub- 
 stances are produced: Solids, which are left in the retorts; 
 liquids, which are condensed in the various coolers; gases, 
 which pass on to the gas holder. 
 
 First. The solids. These are principally two kinds of 
 carbon. One is coke the principal solid matter found in 
 the retorts as a residue from the soft coal after the latter has 
 ceased to evolve gas. It is merely a form of carbon, some- 
 what spongy in its structure. It is sold for use as fuel. 
 Beside this, the retorts accumulate a sort of scale of a very 
 different form of carbon called gns carbon. It is extremely 
 hard and almost non-combnstible, being even very difficult to 
 remove from the retorts. It is at present somewhat used in the 
 manufacture of the carbon pencils employed in electric lights 
 of the arc variety. Prior to this use it found scarcely any 
 commercial outlet. 
 
 Second. The liquids. The first condensation of liquids 
 takes place in the hydraulic main, where tarry and oily mat- 
 ters condense and accumulate, and are drawn off from time 
 
.. . , 
 
 I .. :' 
 
 
 
ILLUMINATING GAS. '249 
 
 to time into the tar well. Again, in the condensers there is 
 a still futher deposition of liquids, also tarry and oily in 
 their nature. 
 
 These liquids consist of very complicated mixtures of car- 
 bon compounds, but they are of the most interesting char- 
 acter. In the earlier history of the manufacture of coal gas 
 they were regarded as mere nuisances. Little by little, how- 
 ever, chemists have learned to separate the intermingled 
 products, and have thus been able to obtain a number of 
 substances of striking interest and usefulness in the arts. 
 Among the multitudes of substances that go to make up the 
 liquid called coal-tar, some are as yet hardly classified ; 
 others are distinctly recognized, and have uses of great com- 
 mercial importance. Of these latter, two will be mentioned 
 here. These are anthracene and benzol. 
 
 The substance called anthracene, a compound of carbon 
 and hydrogen (C 14 H ]0 ), has sprung into the highest commer- 
 cial importance. This is referable to the fact that it has 
 been found to be a suitable material from which, by chemical 
 processes, there may be manufactured a substance known as 
 alizarin, besides other equally valuable and interesting com- 
 pounds. Alizarin was previously recognized as the coloring 
 matter of chief value in madder root, a substance that has 
 been used as a dye-stuff for above a thousand years. The 
 alizarin, whether of madder or from anthracene, is a coloring 
 matter of the highest value and usefulness. It affords turkey- 
 red, and other colors that are very important because they are 
 extremely brilliant and extremely fast. Its artificial manu- 
 facture, from the anthracene of the filthy and offensive coal- 
 tar, is one of the greatest triumphs of this or any age. 
 
 Another substance found in the coal-tar is benzol, a com- 
 pound of carbon and hydrogen having the formula CJI C . 
 This is the principal material from which, by a variety of 
 well-understood though complicated chemical processes, the 
 well-known aniline colors have been produced. While these 
 colors may well command the admiration of all, on account 
 of their unsurpassed beauty and brilliancy, they are of 
 
250 CHEMISTRY. 
 
 especial interest to the scientist by reason of the chemical 
 laws they illustrate. The preparation of these colors, as a 
 group, ranks second only as a chemical achievement to that 
 of artificial alizarin. 
 
 Third. The gaseous products. The gases generated in 
 the process of the coal-gas manufacture are extremely nu- 
 merous; some of them are of high illuminating power, of 
 which that called ethylene (C 2 H 4 ) is an excellent example. 
 Again, there are some that are combustible, but yet are of 
 slight illuminating power. Substances of this class are pres- 
 ent in the finished product. Hydrogen and carbon monoxide 
 (CO) may serve as examples. There are always present also 
 gases that are either injurious to the illuminating power or 
 are otherwise objectionable. For example, nitrogen is 
 always present, and it is not practicable to remove it from 
 the gas. It contributes nothing to the value of the product. 
 Again, certain sulphur compounds, like sulphuretted hydro- 
 gen, are usually present. These indeed burn, but they give 
 rise to offensive and unwholesome oxides of sulphur. 
 
 The sketch thus given, while it but imperfectly describes 
 the wonderful industry in question, with its various well- con- 
 trived and delicate nppliances, serves, however, to give some 
 idea of the importance of the operation from a chemical 
 point of view, and the mine of rich materials its carbon com- 
 pounds offer to chemical students. 
 
SILICON. 251 
 
 CLOSING CHAPTER. 
 
 CHAPTER XXVIII. 
 
 SILICON. 
 
 |ILICON may well be considered important on ac- 
 count of its' quantity in the earth, if on no other. 
 In an earlier chapter it has been shown that 
 oxygen exists in our globe including its atmos- 
 phere and its oceans in an amount equal to about one half 
 of the weight of the whole. Now silicon exists in a quantity 
 equal to about one fourth of this entire weight. In the solid 
 earth, however, neither of these substances exists in the un- 
 combined form. These facts seem to involve as a necessary 
 consequence that they exist in the earth, to a large extent, 
 combined with each other ; indeed this is found to be the 
 case. The principal earthy matter of our planet is the com- 
 pound of silicon and oxygen, existing either alone, in the form 
 of sand, quartz, rock-crystal, and similar minerals, or else in 
 combination with other well-known abundant earth mate- 
 rials, such as oxides of calcium, magnesium and aluminium. 
 It has already been stated that carbon is the characteristic 
 element of animal and vegetable matters ; so silicon is the 
 characteristic element of mineral matters. Thus granite, and 
 similar archaic rocks, contain approximately twenty-five per 
 cent, of silicon. 
 
 In nature silicon performs its important office as a con- 
 stituent of rock material, with a fitness that is referable 
 largely to the high degree of stability possessed by most of 
 its compounds. The permanence of the materials of the 
 earth's surface under the influence of heat, water, frost, and 
 similar agencies, is an illustration of this principle. 
 
CHEMISTRY. 
 
 Silicic oxide (SiO a ), occurs on our globe in many different 
 forms, of which diatomaceous earth and rock crystal may be 
 mentioned. 
 
 Diatomaceous earth is a powdery material found in abun- 
 dant deposits in many parts of the world. Its characteristic 
 
 FIG. 74. Diatomaceous earth as seen through the microscope. 
 
 structure, when examined under the microscope, reveals its 
 nature ; then it is seen to be made up of the shells of minute 
 vegetable organisms called diatoms. These assume a great 
 many beautiful forms, and some of them are checkered all 
 over with markings of such extreme fineness that they have 
 
SILICON. 
 
 253 
 
 been used as test objects for trying the resolving power of the 
 objectives of microscopes. This kind of earth is employed, 
 as has already been stated, in the preparation of dynamite. 
 
 Quartz sometimes occurs in colorless transparent masses of 
 great beauty and clearness, called rock crystal. The ame- 
 thyst is the same substance slightly colored by compounds 
 of the metal manganese, while quartz exists of a variety of 
 
 FIG. 75. Mass of natural quartz crystals. 
 
 other shades, in some of which it is prized as a gem. Quartz 
 generally assumes forms of a hexagonal tendency ; they 
 are often hexagonal prisms terminated by hexagonal pyr- 
 amids. 
 
 Quartz and the finer and purer varieties of sand are used 
 largely in the manufacture of glass. The silicic oxide here 
 displays what may be expressed as its acid tendencies ; for in 
 the manufacture of glass it is fused with sodic carbonate, 
 and then the silicic oxide displaces the carbon dioxide 
 
254 CHEMISTRY. 
 
 from the sodic carbonate ; as a result there is formed 
 what must be regarded as a true salt, or a mixture of salts, 
 that in the simplest kind of glass may be termed sodic sili- 
 cate. 
 
 Closing Words. The course laid out in the preface is 
 now terminated with silicon, as there planned. From scien- 
 tific considerations, this is a natural ending ; it seems to be 
 appropriate on another account also. After the reader has 
 been carried, in thought, among the various gaseous ele- 
 ments that make up atmosphere and oceans, it seems suit- 
 able that we should say farewell to him upon the discussion 
 of that element that may be called the characteristic 
 material of our solid earth. 
 
INDEX 
 
 [THE NUMBERS REFER TO PAGES-! 
 
 Abel, Sir F. A., 189. 
 Acid, Hydriodic, 45, 105. 
 
 Hydrobromic, 45, 105. 
 
 Hydrochloric, 83. 
 
 Hydrofluoric, 105, 106. 
 
 Nitric, 174. 
 
 Oleic, 241. 
 
 Palmitic, 241. 
 
 Stearic, 241. 
 
 Sulphuric, 32, 34, 156. 
 Affinity, Chemical, 41. 
 Air, Atmospheric, weight of, 1<8. 
 
 composition of, 178. 
 
 fitness for its uses, 182. 
 
 not a compound, 182. 
 Alcohol, Ethyl, 239. 
 
 Methyl, 239, 240. 
 Alcohols, 239, 240. 
 Aldehydes, 239. 
 Alizarin, 249. 
 Alkali trade, 86, 88, 99. 
 Allotropism, 121, 199. 
 Amethyst, 253. 
 Ammonia gas, 171. 
 Ampere, 101. 
 Anthracene, 249. 
 Atmosphere, The, 177. 
 Atom, 37, 38. 
 Azote, 167. 
 
 Bacon, Roger, 185. 
 Balard, 93. 
 Balloons, 68. 
 
 Centenary of, 77. 
 
 Proclamation on, 71. 
 Barilla, 100. 
 Battery, Galvanic, 58. 
 Benzol, 234, 249. 
 Berthollet, 86. 
 Berzelius, 2%, 24. 
 Beverages, Effervescing. 231. 
 Biot, 55, 73. 
 Bittern, 93. 
 Black, Joseph, 57, 70. 
 Bleaching, 91. 
 
 by sulphur, 153. 
 
 powder, 86. 
 
 Blowpipe, Compound, 125. 
 Bone Coal, 208. 
 Borax, 161. 
 Boron, 161. 
 Brandt, 195. 
 Bromine, 93. 
 Brougham, Lord, on Cavendish, 55. 
 
 Calcaroni, 147. 
 Carbohydrates, 241. 
 Carbon, 207. 
 
 decolorizing by, 238. 
 
 dioxide, 227. 
 
 gas, 248. 
 
 infusibility of, 220. 
 
 monoxide, 226. 
 Cavendish, Henry, 54. 
 Charcoal, 207. 
 
 animal, 208. 
 Chemistry defined, 8. 
 
 organic, 232. 
 
 scope of, 10. 
 Chlorine, 79. 
 Chloroform, 239. 
 Coal, 211. 
 Coke, 248. 
 
 Combustion, by oxygen, 118, 128. 
 Compound, chemical, idea of, 57. 
 Compounds, 11. 
 
 binary, 29. 
 
 ternary, 31. 
 Courtois, 101. 
 Cupric nitrate, 175. 
 
 Daguerre, 96. 
 
 Dalton, John, 48. 
 
 Davy, Humphry, 54, 81, 101. 
 
 de Morveau, 20. 
 
 De Rozier, 72. 
 
 Despatch, microscopic, 77. 
 
 Diamidogen, 170. 
 
 Diamond, 212. 
 
 Diatoms, 252. 
 
 Dobereiner, 63. 
 
 Dynamite, 192. 
 
 Earth, composition of, 16. 
 diatomaceous, 252. 
 
 Elements, 11. 
 
 Equivalence, 43. 
 
 Ethers, 239. 
 
 Explosives, 184. 
 
 Explosions of mixed oxygen and hydro- 
 gen, 128. 
 
 Ferric nitrate, 175. 
 Fireworks, 187. 
 Fluorine, 105. 
 
 isolation of, 109. 
 Fluor-spar, 105. 
 Fulminates, 188. 
 
256 
 
 INDEX. 
 
 Gas, illuminating, 244. 
 
 natural, 223. 
 
 notion of, 57. 
 Gay-Lussac. 74, 101. 
 Glaisber and Coxwell, 75. 
 Glass, 253. 
 Granite, 251. 
 Graphite, 212. 
 Gun-cotton, 189. 
 Gunpowder, 184. 
 
 Haiiy, 109. 
 
 Hell Gate explosion, 193. 
 Hydrazine, 170. 
 Hydrocarbons, fatty, 238. 
 Hydrogen, 53. 
 
 combustion of, 65. 
 
 diffusion of, 63. 
 
 dioxide, 123. 
 
 preparation of, 58. 
 
 uses of, 66. 
 
 Ice broken up by dynamite, 193. 
 
 machines, 173. 
 Iodine, 98. 
 
 Janssen, 77. 
 Kelp, 100. 
 
 Lampblack, 209. 
 Language, chemical, 20. 
 Larderel, 164. 
 Lavoisier, 20, 22, 111, 167. 
 Leblanc, 101. 
 
 process, 88, 101. 
 Liebig, 94. 
 Light, calcium. 1 :7. 
 
 Marsh gas, 230. 
 Mass, 35. 
 
 Matches, friction, 201. 
 Matter not destroyed, 46. 
 Mayow, John, 113, 167. 
 Mercury, 27. 
 Metal defined, 20. 
 Molecule, 36. 
 Montgolfier brothers, 69. 
 
 Names for substances, 33. 
 Newton, John, 193. 
 Nickles, 107. 
 Nitrogen, 166. 
 
 dioxide, 174, 175. 
 
 pentoxide, 174. 
 
 protoxide, 174. 
 
 tetroxide, 174. 
 
 trioxide, 174. 
 Nitroglycerin, 190. 
 Nobel, Alfred, 192. 
 Nomenclature, chemical, 33. 
 Non-metal, 28. 
 
 Oxygen, 110. 
 Ozone, 119. 
 
 Pelletier, 82. 
 Petroleum, 223, 239. 
 
 Phosphorus, 195. 
 
 red, 198. 
 
 Potassic bromide, 97. 
 Priestley, Joseph, 57, 69, 111, 167. 
 Puymaurin, 108. 
 
 Quartz, 253. 
 
 Radicles, organic, 235. 
 
 References, reading, 12, 18, 25, 28, 34. 40, 
 
 51. 67, 78, 91, 97, 104, 109, 130, 154, 160, 
 
 165, 176, 183, 194, 206, 225. 
 Respiration, 129. 
 Roe, 82. 
 
 Salt, common, 79, 85. 
 
 Scheele, 79, 86. 94, 106, 111, 166, 195. 
 
 Sch rotter, 198. 
 
 Science defined, 7. 
 
 Sea-weed, 99. 
 
 Series, aromatic, 236, 242. 
 
 fatty, 236. 
 
 paraffin, 236. 
 Silicates, 106. 
 Silicic oxide, 252. 
 Silicon. 251. 
 Soda ash, 86, 99. 
 Solvay process, 88. 
 Starch, 241. 
 State, nascent, 124. 
 Substances, compound, 29. 
 
 construction of, 35. 
 
 elementary, 14, 40. 
 
 classification of, 26. 
 
 list of, 15. 
 
 great number of, 10. 
 Suffloni, 164. 
 Sulphur, 144. 
 
 compounds of, 148. 
 
 dioxide. 152. 
 
 trioxide, 155. 
 
 ! Sulphuretted hydrogen, 150. 
 Symbols for atoms, 23. 
 
 Theory, atomic, 48. 
 Trough, pneumatic, 57. 
 Type compounds, 236. 
 
 Van Helmont, 57. 
 Varech, 100. 
 Vinegar, 241. 
 Vitriol, oil of, 156. 
 
 Water, 131. 
 
 as affecting climate, 136. 
 
 as a solid, 135. 
 
 as a working contrivance, 138. 
 
 circulation of, 134. 
 
 composition of, 121. 
 ' decomposition of, 58. 
 
 importance of, 132. 
 
 kinds of, 139. 
 
 rain, 140. 
 
 river, 141. 
 
 sea, 141. 
 
 spring, 142. 
 
 well, 143. 
 Weights, atomic, 15, 45. 
 
 Zinc nitrate, 175. 
 
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