170 PROOFS OF THE COMBUSTIBILITY OF DIAMOND.
This experiment however did not succeed with the diamond ofBrazil.
Lavoisier and Cadet proved that the combustion of the diamond,in close vessels, like all other combustible bodies, ceased as soonas the oxigen was exhausted, and that it only burnt in proportionto die oxigen presented to it.
De Saussure burnt a diamond by means of die blow-pipe.
But as the sole object of all the former experiments was toascertain the combustibility of the diamond, no attention waspaid to the products it afforded during the process; and it stillremained to be determined whether the diamond was a distinctsubstance or one of die known inflammable bodies. No attemptwas made to decide this question, till Lavoisier in 1/77 under-took a series of experiments for this purpose. He exposed thediamond to a large lens, and was thus enabled to burn it in aclose glass vessel. He observed that the air, in which diediamond had been burnt, became absorbed by water; that it dis-turbed lime-water, and that die precipitate obtained was solublein acids with effervescence.
Carbonic acid had therefore been formed. As nothing waspresent but diamond and oxigen, and as carbonic acid gas con-sists of charcoal, oxigen, and caloric, the diamond and oxigenmust have been converted by caloric into the state of carbonicacid gas; and hence the diamond must have been charcoal.
The diamond is therefore a combustible body, which burnsin the same manner in oxigen gas as charcoal does. This strictand accurate consequence is deduced from all the experimentswhich can be imagined to acquire a perfect demonstration. Butthat the diamond was charcoal in its pure and chrystallizcd statewas left to the determination of modern chemists.
Guyton-Morveau applied the solar heat by means of a greatlens, to a diamond placed in a china cup, and surrounded in aproper apparatus, with a confined quantity of oxigen gas.
In one experiment the diamond exhibited, first, a black pointat the angle directly struck by the solar rays; after this, it soou