LAVOISIER. 301 



given out by metallic calces on their reduction to the 

 regnline state. Pie rests in doubt between the two 

 inferences from his experiments the one, that the 

 diamond evaporates into fixed air ; the other, that its 

 vapour changes atmospheric into fixed air. 



Observing the analogy between the diamond and 

 combustible bodies, he exposed it to heat when sur- 

 rounded with fixed air, and atmospheric air was ex- 

 cluded. The evaporation went on, but much more 

 difficultly and slowly. The probability is that the air 

 was not entirely fixed air, else the diamond could not 

 have evaporated at all. 



The production of fixed air by burning charcoal, 

 alcohol, ether, in close vessels had been long known ; 

 but M. Lavoisier carefully subjected charcoal to the 

 same process which he had made the diamond undergo, 

 and the result was nearly the same. 



The conclusion at which he arrived from these ex- 

 periments, is marked by a caution truly philosophic, and 

 as well deserving our admiration, as the sagacity which 

 distinguished the conduct of the inquiry. "We should 

 never have expected," he says, " to find any relation 

 between charcoal and diamond, and it would be un- 

 reasonable to push this analogy too far ; it only exists 

 because both substances seem to be properly ranged 

 in the class of combustible bodies, and because they 

 are of all these bodies the most fixed when kept from 

 the contact of air." He adds, " It is far from being- 

 impossible that the blackish matter should come from 

 surrounding bodies, and not from the diamond itself." 



It is needless to remark how very near he was, in 

 this inquiry, to making the discovery that diamond and 

 the pure carbonaceous matter are identical, and that 

 both form alike fixed air by their union with another 

 and a gaseous substance. Dr. Black had shown, nearly 

 twenty years before, that fixed air was the product of 

 the combustion of charcoal. Had M. Lavoisier per- 

 formed his experiments on that combustion with a little 



