Page:Experimental researches in chemistry and.djvu/26

1818.]

was the first to show that the diamond was capable of supporting its own combustion in oxygen without the continued application of extraneous heat, and he thus obviated one of the anomalies exhibited by this body when compared with charcoal. This phenomenon, though rarely observed, is easily exhibited. If the diamond, supported in the perforated cup, be fixed at the end of a jet, so that a stream of hydrogen can be thrown on to it, it is easy, by inflaming the jet, to heat the gem, and whilst in that state to introduce it into a globe or flask containing oxygen. On turning off the hydrogen the diamond enters into combustion, and will remain burning until nearly consumed. The loss of weight in the diamond, the formation of carbonic acid, and the actual combustion are thus very easily shown.

the course of the experiments which Sir Humphry Davy made at Florence on the combustion of the diamond, he discovered that when the gem began to burn in an atmosphere of pure oxygen, having free access to it on all sides, it would continue burning, though the original source of heat were removed, until the particles were rendered so small as to be too readily cooled by the little platinum tray which supported them. (Philosophical Transactions, 1814, p. 557.) In consequence of this observation, an idea arose, that if the diamond were well heated, and then introduced into oxygen, it would go on burning, and afford an easy method of exhibiting its combustibility. Upon trial this was found to be the case, and a notice to that effect put in this Journal (see shove). Since then, an apparatus of this kind has been perfected, and is now represented in Plate I. fig. 1.

It consists of a glass globe, of the capacity of about 140 cubic inches, furnished with a cap, having a large aperture; the stopcock, which screws into this cap, has a jet A rising