Chap. IL] Chemical Philosophy. 9o 



blished a principle which has been in substance 

 generally adopted by the piiiiosophical world since 

 that time. 



At an early period of the eighteenth century 

 Stahl, an eminent German chemist, published his 

 theory of Phlogistoii, wliich produced one of the 

 most remarkable revolutions in chemical philosoj)hy 

 that ever occurred*. This theory had been in- 

 vented and published, in the preceding century, by 

 Becher, a philosopher of Germany ; but he died 

 before it obtained that character and currency 

 which it afterwards acquired. It was reserved for 

 Stahi to adopt and systematise his doctrines in a 

 manner so plausible and consistent as to secure for 

 them a general reception. According to this cele- 

 brated theorist there is only one substance in na- 

 ture capable of combustion, which, therefore, he 

 called Phlogiston ; and all those bodies which can 

 be made to burn contain more or less of it. Com- 

 bustion is merely the separation of this substance, 

 which, during the process, flies off, leaving behind 

 the incombustible body with which it was connect- 

 ed. He supposed the conversion of sulphur into 

 an acid, by the action of heat, most completely to 

 illustrate and confirm his doctrine; and, indeed, 



* George Ernest Stahl was born in Franconia, in J660, auJ 

 died in 1/34^ in the 75th year of his age. He was undoubteJIy 

 a man of great talents and learning, and the author of many 

 valuable works ; the most important of which relate to hi.s sys- 

 tems of Medicine and of Chemistrj/. He publislied an edition of 

 the Phj/sica Subterranea of Becher, after tlie death of that great 

 chemist, and adopted the theory which tliis work displayed ; but 

 he simplified and improved it so much, that he made it entirely 

 his own 5 and accordingly it has been ever since known by tixc 

 nzme of the StaJdian theoi-v. 



