352 



SCIENCE. 



[Vol. XIX. No. 490 



for the basis of a science, until late in the last century the 

 foundation of chemistry as an exact science was established 

 mainly through the labors of such men as Priestley, Scheele, 

 Cavendish, and Lavoisier. To the latter especially is honor 

 due for introducing the balance as a means of conducting 

 chemical operations on a quantitative basis. The first great 

 event of this period was the discovery of oxygen gas as a 

 constituent of tlie atmospliere by Priestley, and it was soon 

 followed by a determination of the composition of water, for 

 which Cavendisli receives credit. The classic experiment of 

 Lavoisier, in which he ascertained the quantitative proportion 

 of oxygen in the atmosphere, was the beginning of definite 

 ideas concerning the composition of matter. The earlier 

 part of the present century was honored by the brilliant re- 

 searches of Sir H. Davy, Gay Lussac, Dalton, Berselius, and 

 other investigators, which contributed so largely toward the 

 foundations of modern chemistry, and which resulted in the 

 law of gaseous combination of Gay Lussac, the laws of 

 definite and multiple proportions of Dalton, and the law of 

 Avogardro relating to the molecular composition of matter. 

 These deductions were followed by many theories, which 

 were later modified or replaced by others as new facts were 

 discovered, until there has resulted a substantial system of 

 nomenclature and theoretical principles, sufBcient at least 

 for working hypotheses, and sufficient to explain the greater 

 portion of well-authenticated facts. Of recent contributions 

 to chemical theories probably there are none of greater ser- 

 vice in classification and arrangement, or that afford better 

 opportunities for speculative research, than the periodic law 

 which we owe to Newlands, Lothar Meyer, and Mendelejeff. 

 The application of chemical principles seldom precedes a 

 good understanding of the principles themselves. Opera- 

 tions may indeed be carried on in a haphazard fashion ac- 

 cording to empirical rules, but the results are apt to be 

 unsatisfactory. We should therefore expect to see the de- 

 velopment of technological chemistry following in certain 

 lines the general advancement in scientific knowledge, and 

 it is not difficult to understand the marvellous growth in 

 applied chemistry during the last fifty years. Probably the 

 most important branch of chemical industry that has ever 

 been created is the manufacture of sulphuric acid. There is 

 scarcely a commercial process involving chemical changes 

 that is not dependent directly or indirectly upon the use of 

 this acid; and, while at present the yearly production amounts 

 to several million tons, it is only one hundred and fifty years 

 since the lead-chamber process was first devised, and only 

 one hundred years since Chaptal introduced the improve- 

 ments for the continuous process now in use. A scarcely 

 less important branch of industrial chemistry is that of 

 bleaching, which resulted from the application by Berthollet, 

 in 1788, of the properties of chlorine, already discovered by 

 Scheele, in 1777, to destroy certain coloring principles without 

 injury to the vegetable fibres. The manufacture of illumi- 

 nating gas, which is such an important factor in modern 

 life, was first attempted in 1798, and outside lighting with 

 gas in 1813. 



Many other illustrations might be presented to show how 

 recent is the growth of technological chemistry, but it is in 

 the domain of organic chemistry that the development has 

 been most wonderful. Here is a quantity of urea, which, 

 as everyone knows, is a constituent of various fluids in the 

 circulation of animals. In 1828 the illustrious chemist 

 Woehler obtained this substance simply by heating ammo- 

 nium cyanate, and it was the first instance of the artificial 

 preparation of a substance of organic origin. This was the 



beginning of synthetic organic chemistry. In attempting to 

 illustrate what has since been accomplished in this field, we 

 will select as a single example the multitude of substances 

 that have been obtained from coal-tar, a bye-product in the 

 distillation of coal for illuminating gas, and we will ask 

 your attention to this chart, which shows a graphical arrange- ■ 

 ment of many of these compounds in their genealogical de- 

 scent from coal. 



With this brief review of the development of the chemical 

 laboratory and the purposes of laboratory instruction, a 

 question will doubtless arise as to its future efficiency in 

 scientific education, and especially as to the part it will be 

 expected to perform in promoting the material interests of 

 society. While the utilitarian principle of the latter aim 

 wojld naturally become the more important feature of 

 laboratory training, in the school of science it should never 

 be forgotten that whatever of mental culture or discipline 

 the student receives must be derived from the courses of 

 study that are intended as a preparation for his special voca- 

 tion. Constant vigilance is therefore necessary to restrain 

 the natural disposition of the average student, which leads 

 him to avoid all possible mental exertion and to concentrate 

 his energy upon the mechanical side of routine laboratory 

 practice. 



The elementary courses of the freshman year constitute 

 the formative period, and if correct habits are early estab- 

 lished, the more advanced work of later years will be under- 

 taken in the true spirit of scientific study. But if, on the 

 other hand, the student falls into careless or inditferent 

 methods, it is rarely that he recovers from them. Concern- 

 ing the preparation that must be provided to meet the de- 

 mands of the future in applied chemistry, the foundation 

 will be chemical analysis. No process involving chemical 

 changes can be conducted intelligently and economically un- 

 less it is carefully controlled by a complete knowledge, not 

 only of materials employed and valuable products obtained, 

 but also of slags, gases, and all waste products. In the great 

 smelting works in Europe ores are purchased for everything 

 of value they contain. If a gold or silver ore contains, for 

 example, arsenic, antimony, nickel, zinc, and bismuth, in 

 appreciable quantities, the process of smelting will have due 

 reference to the separation of every one of these constituents. 

 In America, with enormous stores ot the richest ores and 

 supplies ready at hand, miners and manufacturers have 

 found the principal constituents too profitable to waste time 

 in the recovery of bye-products. Many a western ore-dump 

 will richly repay for reworking to recover what at first was 

 thrown aside as unprofitable material, and in several direc- 

 tions this fact is even now receiving attention. If the price 

 of coal in Cleveland was twelve dollars per ton, as it is in 

 Switzerland, instead of two dollars per ton, the price now 

 paid here, instead of an atmosphere laden with valuable fuel, 

 the process of combustion would be controlled so that noth- 

 ing but legitimate constituents of smoke could escape. Im- 

 portant changes in this respect, however, are in progress, 

 and manufacturers are appreciating more fully the impor- 

 tance of accurate scientific knowledge and the services of 

 skilled analysts. 



Allusion has been made to a higher field for the employ- 

 ment of educated chemists than that of analytical chemistry, 

 and it is one in which we may expect extensive develop- 

 ments. It is a familiar fact that many materials in daily 

 use can only be obtained by importation from other coun- 

 tries; but the immense quantities of certain manufactured 

 products annually imported may not be generally appre- 



