[ 295 ] 



XLIII. Experiments on the alleged Conversion of Carbon 

 into Silicon. By R. H. Brett, Ph. Z)., and J. Denham 

 Smith, Esq. 



To Richard Phillips, Esq. 



Dear Sir, 



IN the Transactions of the Royal Society of Edinburgh of 

 this year, some experiments have been detailed by Dr. 

 S. M. Brown, announcing the startling discovery, that carbon 

 in certain states of combination is susceptible of conversion 

 into silicon, and inviting a repetition of the trials made by 

 the author. 



Anxious to satisfy ourselves respecting the accuracy of the 

 statements made by Dr. Brown, we instituted the subjoined 

 experiments for the purpose of verifying the results which he 

 details. 



In his experiments Dr. Brown has made use of paracyano- 

 gen, obtained by the decomposition of the bicyanide of mer- 

 cury; the paracyanogen employed by us was produced by 

 the decomposition of hydrocyanic acid ; this was of a brownish 

 black colour, and soluble in sulphuric acid, from which it was 

 precipitated on the addition of water. It contained traces of 

 sulphate of lime and iron. 



We have deemed it unnecessary to repeat the whole of the 

 numerous and, in many cases, prolonged experiments given 

 in the paper, but have selected those which bore most directly 

 on the. stated transformation; the modes of procedure and 

 the results arrived at by us, we shall describe without explana- 

 tion or comment. 



In page 231 of the Transactions we find it stated, that a 

 tightly luted Berlin porcelain crucible, filled with paracyano- 

 gen, was imbedded in stucco paste and exposed to a white 

 heat for an hour and a half. The residue of this experiment 

 was a dark brown infusible substance like charcoal ; this, when 

 ignited with carbonate of potash, and the product treated with 

 hydrochloric acid, is described as leaving a fine white gritty 

 powder insoluble in acids and alkalies, infusible in micro- 

 cosmic salt, and dissolving with effervescence in fused car- 

 bonate of potash, and then forming a solution in water, from 

 which it was separable as a bulky gelatinous precipitate by 

 acids, which precipitate was soluble both in acids and al- 

 kalies, and insoluble in either after ignition to redness. It is 

 further stated, that " two grains of the dark ignited substance 

 procured by the last process yielded 4*11 grs. of silicic acid ; 

 one grain, 2 # 0G grs., and 0*8 gr. 1*57." 



This experiment was repeated in the following manner: — 50 



