Wells & Foote — One Hundred Years of Chemistry. 259 



Aet. IX. — The Progress of Chemistry during the past 

 One Hundred Years; by Horace L. Wells and Harry 

 W. Foote. 



Introduction. 



As we look back to the time of the founding of the 

 Journal in 1818, we see that the science of chemistry had 

 recently made and was then making great advances. 

 That the scientific men of those days were much 

 impressed with what was being accomplished is well 

 shown by the following statement made in an early num- 

 ber of the Journal (3, 330, 1821) by its founder in 

 reviewing Gorham's Elements of Chemical Science. He 

 says : ' ' The present period is distinguished by wonderful 

 mental activity; it might indeed be denominated as the 

 intellectual age of the world. At no former period has 

 the mind of man been directed at one time to so many and 

 so useful researches." 



A very remarkable revolution in chemical ideas had 

 recently taken place. Soon after the discovery of oxy- 

 gen by Priestley in 1774, and the subsequent discovery 

 by Cavendish that water was formed by the combustion 

 of hydrogen and oxygen, Lavoisier had explained com- 

 bustion in general as oxidation, thus overthrowing the 

 curious old phlogiston theory which had prevailed as the 

 basis of chemical philosophy for nearly a century. 



The era of modern chemistry had thus begun, and the 

 additional views that matter was indestructible and that 

 chemical compounds were of constant composition had 

 been generally accepted at the beginning of the nine- 

 teenth century. 



Dalton had announced his atomic theory in 1802, hav- 

 ing based it largely upon the law of multiple proportions 

 which he had previously discovered, and he had begun 

 to express the formulas for compounds in terms of 

 atomic symbols. 



In 1808 Gay-Lussac had discovered his law of gas com- 

 bination in simple proportions, 1 a law of supreme import- 

 ance in connection with the atomic theory, but neither he 

 nor Dalton had seen this theoretical connection. Avo- 



1 It appears that the most accurate experimental demonstration ever made 

 of this law was that of E. W. Morley, published in the Journal (41, 220, 

 276, 1891). He showed that 2-0002 volumes of hydrogen combine with one 

 volume of oxygen. 



