1826.] X>A Colquhoun on a new Form of Carbon, 11 



stated by Berthollet to exist in native graphite." I was parti- 

 cularly observant, therefore, in trying the effect of the tests to 

 which I submitted the mammillary carbon, to discover whether 

 any traces of iron entered into its composition, and I can affirm 

 with perfect confidence that in the specimens examined by me, 

 not the slightest indications of its presence existed. It follows, 

 therefore, that iron is in no respect necessary to the formation 

 of the carbon of the mammillated and metallic-looking variety, 

 and that if it ever occur as a constituent of such masses, it may 

 nevertheless be regarded as foreign and extraneous. 



Such are a few of the appearances presented by these interest- 

 ing varieties of carbon, of which it has been the object of this 

 notice to give some account. Of all the different forms assumed 

 by that substance, it is believed there are few more singularly 

 elegant and beautiful than that of the long slender lustrous fila- 

 ments, which indeed require to be seen in order to be justly 

 appreciated. The new and unprecedented nature of this shape 

 of carbon also gave it a strong claim to our first regard. And 

 yet, perhaps, the most surprising of its characteristics, that 

 which points to the most important views of the wonderful and 

 mysterious operations of nature, though carrying the onward 

 eye towards a goal that is placed as yet beyond the ken of 

 chemistry, is one that is possessed in common both by the fila- 

 mentous and by some of the mammillated varieties. This is the 

 strong indication which their external characters afford of their 

 forms having been assumed out of a state of fusion : although, 

 from considerations soon to be noticed, they probably owe their 

 form to a totally different cause. The metallic and fused-like 

 aspect is so strongly marked, that it may be safely said, the 

 mere eye or tact of even the most experienced observer, could 

 not point out any character which seems to lead to another 

 origin. Now it is well known that hitherto, in the most intense 

 heats which artificial means have been able to create, carbon 

 has been found to exhibit not the slightest traces of even a 

 tendency towards fusion. Nevertheless, in the varieties just 

 described, in temperatures certainly below an ordinary white 

 heat, we have almost all the evidence of this substance having 

 been completely fused, which we can possess, short of actually 

 seeing it melted to liquid. We have it, in one case, assuming a 

 form entirely unknown before, which of itself would indicate 

 that it passed through a state of existence before inexperienced; 

 and we have in all respects the external characters and appear- 

 ances of a body which had been fixed from a state of fusion. It 

 should also be remarked that on the unlikely hypothesis of the 

 carbon having undergone fusion, this could have taken place 

 only in the moment of mammillary or filamentous formation ; for 

 when the substance so formed is again subjected to intense 

 artificial heat, it remains, as happens with all the other forms of 



