1826.] of the 7iew Varieties of Carbon J S^c, 193 



underrated some fact in the case, which has a material bearing 

 on the cause of the phaenomena to be explained ; but it does 

 appear to me that these phaenomena are susceptible of a ready 

 and satisfactory explanation, for which Dr. C. himself has pro- 

 vided the materials. 



For the purpose of showing this, a brief recapitulation of the 

 principal facts related will be necessary. A current of an aeri- 

 form combination of carbon is made to act on iron heated 

 nearly to whiteness, and defended from the action of atmospheric 

 air. The gas undergoes decomposition, a portion of its carbon 

 combines with the iron, producing steel, whilst another portion 

 is precipitated in various forms, but in a state of purity. And 

 the characters of some of the varieties of the carbon thus pro- 

 duced, indicate them to have been in a state of fusion at the 

 moment of their formation. But Dr. Colquhoun views the infu- 

 sibility of carbon at the temperature to which the gas is 

 subjected, as being at present an insuperable difficulty in the 

 explanation of the phsenomenon ; as one which renders it 

 impossible to understand the nature of the process by which the 

 carbon is deposited, either in the new method of making steel, or 

 in the operation of obtaining gas from coal. 



I may here observe, before proceeding to offer what I conceive 

 to be the rationale of this process, that the statement made by 

 Dr. C. that carbon has not exhibited even a tendency to fusion 

 in the most intense artificial heats, is not exactly correct ; for 

 although it is unquestionably one of the most infusible of bodies, 

 yet distinct evidence of the partial fusion both of graphite and of 

 the diamond, were obtained by the late Dr. E. D. Clarke, in his 

 experiments with the oxy-hydrogen blowpipe. But even if there 

 were no evidence of the fusion of carbon by artificial means, it 

 is not obvious, I think, why that circumstance should militate 

 against the belief, that a substance bearing every appearance of 

 having once been liquid, should in reahty have been in that 

 state. All that could fairly be said, would be, that in experi- 

 ments instituted for the purpose of endeavouring to fuse carbon, 

 it remained infusible, at a temperature equal or even superior to 

 that to which it could have been subjected, by the process in 

 question. And this would be merely one of the many cases in 

 the arts dependent on chemical principles, in which certain 

 phasnomena take place, naturally, as it were, in certain opera- 

 tions, that cannot be produced by experiments expressly directed 

 to those objects ; and which, in fact, are as inexplicable, and 

 as difficult of access, as many of the operations in whicli the 

 powers of nature are alone concerned. 



And now, merely remarking that my reason for regarding the 

 fusion of graphite as part of the evidence of that of carbon 

 having been effected, will appear in a subsequent communication, 

 I proceed to submit, with much deference, the rationale of the 



Neio Series, vol. xii. q 



