'HIStORT of the SOCIEtr. \i 



CHEMISTRY.' 



Sir George Mackenzie, Ban. read a paper containing an »8c:. 



account of experiments which he had made on the Combuaion onfhfc'oi" 

 of the Diamond. S"d".'''' 



What follows is a fliort abftraft of this paper; the paper 

 itfelf having been publiihed in Nicbol/on's Journal for July 1800. 



The firfl objeifl of thefe experiments was to afcertain the tem- 

 perature at which the combuftion of the diamond takes place. 

 For this purpofe a diamond, together with a pyrometer of 

 WedgewOod, was placed on a piece of baked clay, and pufhed 

 gradually into the muffle : when both were perfedly red through- 

 out, the pyrometer was withdrawn, and indicated 13'. The 

 diamond had acquired the dim milky appearance which is known 

 to indicate an incipient combuftion. It was then replaced in the 

 muffle, together with the pyrometer ; and the heat, being flowly 

 increafed till a glow, indicating that the diamond was com- 

 pletely on fire, appeared, was continued, as equal as poffible, till 

 the diamond was totally confumed. The pyrometer, when 

 meafured, indicated 14°. In another experiment, the heat re- 

 quired to produce the glow was 15 % and at this temperature 

 the diamond was v^'holly confumed. 



Similar experiments were repeated, with different diamonds, 

 and with nearly the fame refult, which fhews that the heat re- 

 quired for their combuftion is much lefs than it has hitherto 

 been fuppofed. 



Guyton's experiment of converting iron into fteel by means 

 of the diamond, was repeated in the following manner : Into a 

 hollow cylinder of foft iron, clofed at one end, feme fmall dia- 

 monds were put, and a ftopper of the fame iron being after- 

 wards applied, the two pieces were rivetted together at the. top. 



B2 The 



