MancJiester Memoirs, Vol. Ivii. (191 3), No. ID- 29 



II. Prikstley and Lavoisier. 



The documents so far discussed have either been 

 directly connected with John Dalton, or have related to 

 the period of chemistry influenced by his theories. The 

 Daltonian era follows the memorable epoch in which the 

 Phlogiston theory was overthrown b\' Lavoisier. This 

 theory itself had a long reign, lasting for more than a 

 century after it had been expounded by Becher in 1670, 

 and later amplified by Stahl. The theory is nowadays 

 often ridiculed, but it has nevertheless had a great, and, on 

 the whole, wholesome influence on chemistry. Chemistr)' 

 was, towards the end of the seventeenth century, only 

 slowly emerging from the alchemistic labyrinth, which 

 was succeeded by the iatrochemistic stage. Originally 

 the companion of philosophers, later the handmaid of 

 ph}-sicians, it finally entered upon an independent life. 

 At this period the introduction into chemistr)- of great, 

 far-reaching ideas was of the utmost importance. To 

 find the laws underlying the processes, as we sa}- nowa- 

 da}-s, of oxidation and reduction, must be reckoned no 

 small advance.-^ This step was made under the auspices 

 of the Phlogiston theory, and the man who did the most 

 important work in the field of pneumatic chemistry was 

 himself to the end a staunch supporter of this theor)-. To 

 this man, Joseph Priestley, and his great adversary in 

 theory, Lavoisier, the documents hereinafter communi- 

 cated relate. 



-^ The best contribution to the history of this period, which has often 

 been misrepresented strangely by national bias (especially by Wiirtz from the 

 French and Volhard from the German point of view) is imdoubtedly : ' Die 

 Einfiihrung der Lavoisierschen Theoric im besonderen in Deutschland,' by 

 G. W. A. Kahlbaum und A. Hoffmann. Leipzig, 1897. 



