A CHAPTER ON DIAMONDS. 37 



ton de Morveau, and others, consumed tlie diamond, and it was 

 readily dissipated in the focus of the great mirror of Tchirnhausen 

 as"1\Iurray beUeves it subsequently was in that of Parker's burning 

 lens. In the year 1771, Macquer observed the diamond to in- 

 flame. Guyton de Morveau had proved that the diamond was 

 destroyed when projected into red-hot nitre; audit was also burnt 

 by means of melted nitre in a gold tube, by Mr. Tennant. When 

 fragments of diamond were introduced into the brilliant arch of 

 flame, evolved betvveen points of charcoal in the galvanic batteries 

 of the Royal Institution, consisting of 2,000 double plates, and 

 exposing a surface of 128,000 square iHches, they rapidly disap- 

 peared, being completely volatilized. The diamond may be easily 

 consumed, Murray also tells us, by being placed in a cavity of 

 charcoal, and urging on it the flame of a spirit lamp, by means 

 of a stream of oxygen. 



So far the combustibihty of the diamond was completely ascer- 

 tained, but its nature remained, still undetermined. Lavoisier had 

 proved and pointed out that carbonic acid gas was evolved as a 

 product both in the combustion of the diamond and that of char- 

 coal, and thus their identity was inferred. The researches of 

 Clouet, Messrs. Allen and Pepys, and others have confirmed this 

 conclusion. Sir George Mackenzie converted iron into steel, by 

 powdered diamonds. Mr. Children's immense battery consisted 

 of twenty triads, each six feet long by two feet eight inches broad, 

 exposing a total surface of thirty -two feet ; when iron, with dia- 

 mond pov^^der interposed, was exposed to its influence, the iron 

 was converted into steel and the diamond disappeared ; and Mr. 

 Sinithson Tennant having placed the diamond in a gold tube, sup- 

 ported in a state of incandescence, a stream of oxygen, by means 

 of gentle pressure, was made to traverse it, and the result proved 

 that the oxygen was transformed into an equal quantity of car- 

 bonic acid gas, which was found in an opposite receiver, resting 

 over mercury. Sir Humphrey Davy, when at Florence, made 

 some experiments with the Grand Duke's burning lens on the 

 combustion of the diamond. He found that when the gem was 

 introduced into a glass globe supplied with oxygen, and kindled 

 by the lens, it continued to burn after it Avas removed from the 

 focus ; the oxygen was supplanted by an equal volume of carbonic 

 acid gas, while there was no deposit of aqueous vapour. On the 

 other hand, when plumbago and charcoal were consumed under 

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