A HUNDRED YEARS, OF CHEMISTRY. 673 



A HUNDRED YEARS OF CHEMISTRY. 



By F. W. CLARKE, 



CHIEF CHEMIST, UNITED STATES GEOLOGICAL SUKVEY. 



IT is hardly an exaggeration to say that chemistry, as a science, 

 is the creation of the nineteenth century. Chemical facts, in- 

 deed, were known even in remote antiquity; some principles were 

 dimly anticipated long before the century began; Boyle had given 

 the first rational definition of an element; the principal gases had 

 been discovered; great foundations were laid, ready for the super- 

 structure. But the making of bricks is not architecture, nor does 

 the accumulation of details constitute a science. The scattered 

 facts are needful preliminaries, but only with the discovery of laws 

 and the development of broad generalizations does true science 

 begin. 



That truth can be born from error may seem paradoxical, but, 

 nevertheless, the statement is exact. False hypotheses stimulate 

 investigation, and so truth comes at last to light. In the history 

 of chemistry this principle is clearly illustrated. During the eight- 

 eenth century the doctrine of phlogiston was generally accepted; 

 this led to exhaustive researches upon combustion, and from these 

 the science of chemistry received its present shape. Becher and 

 Stahl had taught that every combustible substance contained a com- 

 bustible principle — phlogiston — -and that to the elimination of this 

 principle the phenomena of combustion were due. According to 

 this theory, a metal was regarded as a compound of its calx, or 

 oxide, with phlogiston; hydrogen became a compound of water 

 with phlogiston, and so the truth was curiously inverted. The doc- 

 trine was vigorously and ingeniously defended, and, although it 

 was overthrown by Lavoisier, it had persistent supporters even 

 after the present century began. 



The weak point of the phlogistic theory was its practical dis- 

 regard of the phenomena of weight. That the calx weighed more 

 than the metal was well known, but quantitative considerations 

 were subordinated to those of quality, and the form of matter was 

 studied rather than its mass. 



In 1770 the scientific career of Lavoisier began, and the balance 

 became a chief instrument in chemical research. The constancy 

 of weight during chemical change was experimentally established, 

 and what had been a philosophical speculation — the increatability 

 and indestructibility of matter — became a doctrine of science, a 

 datum of knowledge instead of a hypothetical belief. In 1774 

 Priestley and Scheele independently discovered oxygen, and with 



VOL. LVI. — 54 



