1 2 Combustion of the Diamond. [ 1 820. 



from it, nearly into the centre of the globe ; this is destined to 

 convey a small stream of hydrogen or other inflammable gas. 

 Two wires, c c t terminate at a very little distance from each 

 other, just above this jet, and are intended to light the stream 

 of hydrogen by electFical sparks ; one of them commences 

 from the side of the jet, the other is enclosed and insulated 

 nearly in its whole length in a glass tube : the tube and wire 

 pass through the upper part of the stopcock, and the wire 

 terminates on the outside in a ball or ring, D, at which sparks 

 are to be taken from the machine, either directly or by a chain. 

 On the end of the jet is fixed, by a little socket, a small 

 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 stopcock 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 stopcock, 

 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, lest 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 

 stopcock for a short time, the diamonds may be introduced 

 and the stopcock 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 fl;ime of hydrogen is used to heat the diamonds, 

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



