334 BLACK. 



Cane excited, that we find a conjecture hazarded in the 

 article * Grotte' (vol. vii. p. 968), which appeared in 

 1756, " peut-etre respirent ils (les chiens), au lieu 

 d'air, des vapeurs minerales;" but this was some time 

 after Black's discovery had taught us to distinguish such 

 permanently elastic vapours from atmospheric air. In 

 the article ' Fermentation' (vol. vL p. 523) we find 

 Van Helmont's doctrines of the connexion between 

 fermentation and digestion treated with ridicule, and 

 those who adopted them jocularly called the " fermen- 

 tateurs." 



A few years later, however, the face of things 

 changed. In the ' Supplement,' published in 1776, we 

 find an article on ' Fixed Air,' and a reference to Dr. 

 Black's discovery ; but nothing can be more indistinct 

 than the author, M. Morveau's, ideas respecting it; 

 for he leaves us in doubt whether it be the atmospheric 

 air or a separate substance, and yet he states that the 

 phenomena of fermentation and putrefaction are ex- 

 plained by the evolution or absorption of this air, and 

 that mineral waters derive from its presence their fla- 

 vour. An abstract of M. Venel's book had in 1765, 

 under the head of ' Mineral Waters,' given this explana- 

 tion ; but instead of representing the air combined with 

 the water as a different substance, he calls it " veritable 

 air et meme tres pure." We have, however, seen that, 

 in the following year (1777), M. Morveau's ideas were 

 perfectly distinct on the subject ; for he treats it as a 

 new substance, wholly different from atmospheric air. 

 The slowness with which Black's doctrine made its 

 way in France may be presumed from Morveau's re- 

 mark on causticity, already cited, and also from this, 



