450 New Facts concerning the Diamond. [October, 



diamond of course appeared dull, but not the least appear- 

 ance of blackening was observed, either on the surface or in 

 the interior. Neither was it remarked by M. Jacquelain, 

 when operating with a flame produced by a mixture of 

 oxygen and hydrogen in proportions necessary to form water, 

 or by one composed of a mixture of oxygen and oxide of 

 carbon. The experiment was interrupted several times to 

 examine the diamond, which nowhere presented either 

 brown spots or blackening. 



M. Jacquelain considers that perhaps the surfaces of the 

 diamond have been blackened, and that this has disappeared 

 again owing to contact with carbonic acid, and aqueous 

 vapour at a high temperature : in fact, from the considerable 

 friction resulting from the gaseous mixture escaping from a 

 receiver under strong pressure. However that may be, this 

 experiment proves incontestably that the flame resulting 

 from a mixture of hydrogen and oxygen in the same proportion 

 as in water, is incapable of softening the diamond, and 

 that the combustion of this explosive mixture is far from 

 producing the energetic effect of ioo elements of Bunsen. 

 M. von Baumhauer considers that the transformation of the 

 diamond into coke or graphite by means of heat is still to 

 be doubted ; nor should it be admitted, until it is quite 

 certain that blackening is not the result of chemical action 

 produced by foreign matter, or by the transmission of car- 

 bonaceous particles from the charcoal poles to the surface 

 of the diamond. 



To ascertain whether the diamond would be capable, at 

 white heat, of decomposing water, and burning b}- means of 

 the oxygen contained in it, there was passed over a rough 

 limpid diamond, and also over a cut diamond, a current of 

 superheated steam, in a platinum tube exposed to the heat of 

 a flame of gas urged by a current of air. Although the 

 operation was continued for ten minutes, the diamond was 

 quite brilliant after cooling, and had lost nothing of its 

 weight ; proving, that at this temperature at least the dia- 

 mond suffers no change in an atmosphere of superheated 

 steam. 



It is otherwise, however, when the diamond is kept for 

 some time in an atmosphere of dry carbonic acid. A rough 

 stone, weighing 0'i5i5 grm., was subjected to a white heat 

 for ten minutes in a crucible closed with mica, supplied 

 with dry carbonic acid already flowing, some time before 

 the application of heat ; when cooled, the surface of the 

 diamond was dull and its weight decreased by 0*0015 grm. 

 This experiment was repeated with a cut diamond weighing 



