300 LAVOISIER. 



chiefly recommended to him by their showing that the 

 experiments with alcohol, which he had made with those 

 substances, exhausted the subject of mineral waters. 



But the next important inquiry of this eminent 

 chemist related to the action of heat on the diamond, 

 or, as he very inaccurately termed it, the destruction 

 of the diamond by fire. These experiments were per- 

 formed with great care, and without any regard to 

 expense; to which purpose a public-spirited jeweller 

 also contributed largely. They were performed partly 

 by fire, partly by the great lens of Tschirnausen be- 

 longing to the Academy. The Memoir is in the volume 

 for 1772, Part II., published in 1776; but the experi- 

 ments were not all performed till late in 1773, and the 

 Memoir was probably read in 1774. It was found that 

 some carbonaceous effervescence (as he describes it) 

 could be observed when the heat applied was not very 

 strong, though a stronger heat dissipated the diamond 

 altogether if it was exposed to the air. Hence M. 

 Lavoisier inferred, that beside being a combustible 

 substance, as Newton had sagaciously imagined from 

 its optical qualities, and as Macquer had proved by 

 direct experiment, it is capable of conversion into 

 charcoal. But a more important fact was also ascer- 

 tained. M. Lavoisier examined the air in which the 

 evaporation, as he terms it, of the diamond was per- 

 formed, and he found that it precipitated lime from 

 lime water. Examining the lime thus thrown down 

 he found it to be chalk, and thence concluded most 

 justly that the air produced during the combustion of 

 the diamond was fixed air. This, however, is not his 

 enunciation of the proposition; he only says, that the 

 air in which the diamond had been evaporated had 

 acquired in part the properties of fixed air, or the air 

 which, he correctly says, comes from the effervescence 

 of alkalis and from fermentation, and which, he very 

 erroneously says, (following the mistake into which he 

 had fallen in his experiments on calcination) is the air 



