Combustion of the Diamond. 265 



capsule, B, made of platinum foil. This capsule is pierced 

 full of small holes, and serves as a grate to hold the diamonds. 

 Its distance is about three quarters of an inch from the end 

 of the jet ; and the arm, by which it is supported, is bent round, 

 so that the stream of hydrogen shall not play against it. The 

 stop-cock screws, by its lower termination, on to a small pillar 

 fixed on a stand, and at the side of this pillar is an aperture 

 by which a bladder filled with gas may be connected with the 

 apparatus. 



On using the apparatus, the diamond is to be placed in the 

 capsule, and then the globe being screwed on to the stop-cock, 

 the latter is to be removed from the pillar and placed on the 

 air-pump ; the globe is then to be exhausted and afterwards 

 filled with pure oxygen: or, least the stream of oxygen in 

 entering should blow away the diamond, the globe may be filled 

 with the gas first, and then, dexterously taking out the stop- 

 cock for a short time, the diamonds may be introduced and 

 the stop-cock replaced. The apparatus is then to be fixed on 

 the pillar, and a bladder of hydrogen gas attached to the 

 aperture. Now, passing a current of sparks between the wires, 

 a small stream of hydrogen is to be thrown in, which inflaming, 

 immediately heats the capsule and diamonds white hot ; the 

 diamonds will then enter into combustion, and the hydrogen may 

 be immediately turned off and the bladder detached. The 

 diamonds will continue to burn, producing a strong white heat, 

 until so far reduced in size as to be cooled too low by the 

 platinum with which they lie in contact. 



When the flame of hydrogen is used to heat the diamonds, 

 it is evident a little water will be found in the globe, but this 

 is of no consequence except in attempts to detect hydrogen in 

 the diamond, the inconvenience may be obviated, if required, 

 by using the flame of carbonic oxide. As however no hydrogen 

 has at any time been detected in tlie diamond, it is better to 

 use that gas as the heating agent ; for then the carbonic acid, 

 produced by the combustion, is unmixed with that from any 

 otlicr source, and niay be collected, and its quantity ascertained. 



M. F. 



