

Chemical Science. 161 



conducting power of these bodies for electricity is insisted on, and 

 which we regret we have not room to state. Professor Sillimau 

 says, " It will now, probably, not be deemed extravagant if we 

 conclude that our melted carbonaceous substances approximate very 

 nearly to the condition of diamond." Admitting this, yet the interest 

 and importance which would attach to the discovery of the artificial 

 production of diamond, justifies us in reserving our doubts whilst 

 reading Professor Silliman's statements. The experiments are very 

 important, but many doubts arise, even whilst reading the description 

 only. That the vapour, which is described as rising from the charcoal 

 and plumbago, and which formed a kind of frit, and was supposed 

 to be the matter of the globules, could be carbon in any state, is 

 almost impossible ; it neither accords in its properties with charcoal 

 or diamond. Sir G. Mackenzie shewed that a mere red heat was 

 sufficient to burn solid diamond even in the common atmosphere, so 

 that it is hardly probable a vapour at all like diamond could escape 

 through the air so intensely heated, and condense on a glass-plate 

 unburnt. The properties of the globules, also, continually fall short 

 of those of the diamond. We would beg to suggest what we think 

 would be a ready test of their nature, namely, trial by the blow-pipe. 

 The diamond, heated with borax on the platinum wire, before the 

 blow-pipe, undergoes no change; we are afraid the globules would 

 not stand the trial, but hope the Professor will be induced by its 

 readiness to submit them to it. 



3. Action of Nitric Acid- on Charcoal, -production of Cyanogen. — 

 The following account is abstracted from a paper by Dr. Cutbush, 

 in Silliman's Journal, vol vi. 149. Nitric acid was poured on to 

 charcoal to illustrate the nature of gunpowder by a reference to the 

 composition and decomposition of the acid ; and being left, the mixture 

 became, after the usual action, thick and brown, like artificial tannin. 

 It was thought that perhaps cyanogen might be formed by the union 

 of part of the carbon with nitrogen, at the same time with the car- 

 bonic acid and nitrous gases. The mixture was therefore put into a 

 retort, distilled, and all the products passed through a series of 

 Woulfe's bottles, containing water. Most of the gases were thus ab- 

 sorbed, and the acid solution neutralized by potash. The solution 

 was then tested by sulphate and persulphate of iron, when the colour 

 immediately changed, and became more or less blue, thus proving the 

 presence of cyanogen in the results of the action of charcoal and nitric 

 acid ; so that at the same time that one portion of charcoal has taken 

 the oxygen of the nitric acid, another portion must have taken its ni- 

 trogen. 



The author of the paper observes, that charcoal has the property of 

 absorbing many gases, and particularly hydrogen. Ho asks whether 

 the charcoal he used might not contain hydrogen ; and whether this 

 nascent hydrogen, during the action of the carbon, might not have 



Vol. XVI. M 



