150 NATURE OF THE DIAMOND. 



expei'inn-nts was to ascertain the inflammable nature of the dia- 

 mond, no attention was paid to the products afforded by its com- 

 bustion j and it still therefore remained to be determined whether 

 the diamond was a distinct substance, or one of the knoun in- 

 flammable bodies. Nor was any attempt made to decide this 

 question till M. Lavoisier, in 1772, undertook a series of PXJH ri- 

 ments for this purpose. He exposed the diamond to the heat pro. 

 duced by a large lens, and was thus enabled to burn it in close 

 glass vessels. He observed that the air in which the inflammation 

 had taken jtlace had become partly soluble in water, and pr< dpi. 

 tated from lime-water a white powder which appeared to he ch-iik, 

 being soluble in acids with effervescence. As M. Lavoisier seems 

 to have had little doubt that this precipitation was occasioned by 

 the production of fixed air, similar to that which is afforded by 

 calcareous substances, he might, as we know at present, have in- 

 ferred that the diamond contained charcoal ; but the relation be- 

 tween that substance and fixed air, was then too imperfectly 

 understood to justify this conclusion. Though he observed the 

 resemblance of charcoal to the diamond, yet he thought that no- 

 thing more could be reasonably deduced from their analogy, than 

 that each of these substances belonged to the class of inflammable 

 bodies. 



As the nature of the diamond is so extremely singular, it 

 seemed deserving of further examination ; and it will appear from 

 the following experiments, that it consists entirely of charcoal, 

 differing from the usual state of that substance only by its crystal- 

 lized form. From the extreme hardness of the diamond, a stronger 

 degree of heat is required to inflame it, when exposed merely to 

 air, than can easily be applied in close vessels, except by means 

 of a strong burning lens ; but with nitre its combustion may be 

 effected in a moderate heat. To expose it to the action of heated 

 nitre free from extraneous matters, a tube of gold was procured, 

 which by having one end closed might serve the purpose of a re- 

 tort, a glass tube being adapted to the open end for collecting 

 the air produced. To be certain that the gold vessel was perfectly 

 closed, and that it did not contain any unperccived impurities 

 which could occasion the production of fixed air, some nitre was 

 heated in it till it had become alkaline, and afterwards dissolved 

 out by water ; but the solution was perfectly free from fixed air, 

 as it did not affect the transparency of lime-water. When the 



