[ 282 ] [Book VI. 



CHAP. XLIV. 



OF THE DIAMOND, CONSIDERED AS AN 

 INFLAMMABLE SUBSTANCE. 



Natural Hiftory of Diamonds. Varieties, Internal Struflure. Ex- 

 periments proving the inflammable Nature of we Diamond. Experi- 

 ments ofM. Cadet Of D'Arcet. Vital Air necejjary to the Com- 

 tujtion of the Diamond. Experiments of Lavoifer. Further Expe- 

 riments. Experiments of Mr. Tennant.Tbe Diamond praised to be 

 zrcoal. 



TH E diamond, though (lightly mentioned when 

 treating of gems, belongs properly to the clafs 

 of inflammables. It is the harden: and mofl brilliant 

 of all fubftances. Its fpecific gravity is 3,445, hence 

 it refrafts the rays of light very powerfully ; but it 

 poflefies this power even in a much greater degree than 

 might be fuppofed from its denfity, and hence proceeds 

 its fingular brilliancy. The diamond, properly fo 

 called, is colourlefs ; but it alfo retains this name when 

 it is (lightly tinged either with red or yellow. It 

 is therefore not the colour of the ftone, but its hard- 

 nefs and luftre, which obtain for it the denomination 

 of a diamond. 



Diamonds are found in the Eaft Indies, particularly 

 in the kingdoms of Golconda and Vifaponr : they like- 

 wife come from the Brafils j but thefe lafl appear to 

 be of an inferior quality, and are known in commerce 

 by the name of Portuguefe diamonds. 



Diamonds are ufually found in an ochreous yellow 

 earth, under rocks of grit-done and quartz , they are 

 likewife found detached, in torrents which have carried 

 them from their beds. They are feldom found 



above 



