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On the Combuftion of the Diamond. 55 
@ profound ftudy of urine may préfent to thofe who will be- 
ftow orf it that continued attention which it requires, and 
what influence fuch phenomena may have on the progrefs of 
enimal phyfiology. The authors promife to make known, in 
a fecond Memoir, all the properties which diftinguifh the 
particular matter that characterifes this liquid, which i is the 
moft abundant in it, and which they call urée, ‘as has been 
already faid. 
XIL. Evtrad from the Re; cport repetling Experiments made 
at the Polytechnic School in the Years V. and VI. on the 
- Combuftion of the Diamond. By C. Guyton *. 
asia the diamond is combuftible, is a truth’ which 
Newton, in fome meafure, conjectured; which experience 
has fully confirmed; and refpeéting which it is no longer 
poffible to entertain the leaft doubt. But what is the nature 
of this combuftibility ? My firft.experiments, publifhed in 
1785, on the entire combuftion in nitre in fufion ¢, feemed 
’ to announce that the diamond burnt in it after the manner 
of coal, fince it left an effervefcent alkali; and this fufpicion 
a¢quiyed more reality, after the examination made by La- - 
voifier of the gas remaining in the veflels in which it had 
burnt, and which he Sidad charged with carbonic acid. 
Mr: Tennant has finee furnifhed us with a new proof of 
this important fa&, by repeating the combutftion of the dia- 
mond by nitre in a gold crucible, as I had propofed, in order 
to obtain a refiduum abfolutely free from all foreign matter tf. 
There were, however, fill fufficient reafons to induce us 
‘to difbelieve that the diamond and carbon, or that the dia- 
mond and the carbon extracted from the carbonic acid by the 
noble experiment of Mr. Tennant, were thé fame fubftance. 
Independently of their external charaéters, fo completely 
different, feveral obfervations, which I have already commus 
Micated to the Inftitute, prove that their chemical characters 
* From the Annales de Chimie, No. 91. 
4 Opufeles de Bergman, French edition, Vol, XL. p. 124. 
$ Philofophical Tranfuctions 1797. 
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