294 LAVOISIER. 



nality. Yet we may observe that his paper contains 

 an ingenious theory, explaining the phenomenon of 

 the formation of gypsum on the principles of ordinary 

 crystallization ; and that he has also ascertained the 

 proportion of water required for its solution more 

 accurately than had before been done ; that he gave a 

 systematic view of the whole subject. Qualis ab in- 

 cepto processerat. It is remarkable that all the dis- 

 tinguishing characters of his inquiries in after-times 

 should be found to mark this his first production. 

 We observe the same disputed originality in his ex- 

 periments, the same anticipation of his discoveries 

 by former inquirers, the same superiority of his pro- 

 cesses in point of accurate admeasurement, the same 

 inferiority of his experiments to his reasoning?, the 

 same happy generalization of facts observed by others, 

 the same turn for throwing doctrines and discoveries 

 not his own into one combined system. 



The discoveries of Black had, long before M. Lavoi- 

 sier entered upon his scientific pursuits, directed the 

 attention of philosophers to the important subject of 

 gaseous bodies, to their production by the absorption 

 of heat, and to the combinations into which they enter 

 with other substances, so as to alter the nature of 

 these. The great doctrines of causticity and of latent 

 heat, with the existence of fixed air, and its evolution 

 in respiration, fermentation, and combustion, had been 

 established, and had formed a new era in chemical 

 science. Fixed air was discovered in 1754; latent 

 heat before 1763. Mr. Cavendish had prosecuted 

 these inquiries with success ; he had examined some 

 of the properties both of fixed air and of hydrogen ; 

 had determined their specific gravities, and had shown 

 that they are always the same from whatever sub- 

 stances they may be obtained. His experiments were 

 published in 1766. Soon after this time Dr. Priestley 

 began his brilliant course of discovery. A new scene 

 had been opened to philosophers; they were like 



