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LVIII. Some Observations on Dr. Brett and Mr. Smith's 

 Experiments on the alleged Conversion of Carbon into Si- 

 licon*. By Dr. Samuel M. Brown. 



To Richard Phillips, Esq. 

 Sir, 

 \ S Dr. Brett and Mr. Smith have made the Philosophical 

 -**• Magazine the medium of publication for their M Experi- 

 ments on the alleged Conversion of Carbon into Silicon," I re- 

 quest you to do me the honour of giving the same publicity to 

 these few and brief observations on their letter, while I gladly 

 acknowledge the liberal style of investigation in which the 

 gentlemen in question have undertaken and executed their 

 task. 



Your Correspondents specify, on the very threshhold, that 

 the "paracyanogen employed by them was produced by the 

 decomposition of hydrocyanic acid ;" and this is sufficient to 

 render almost all their experiments of no value. I do not, in- 

 deed, understand the statement. If it be meant that their 

 paracyanogen was prepared by the spontaneous decomposition 

 of anhydrous hydrocyanic acid, they must prove that paracy- 

 anogen can be so produced at all; for M. Gay-Lussac found 

 that hydrocyanic acid is wholly resolved into ammonia and a 

 brownish-black matter, inferred to be "un azoture de carbone," 

 which cannot be paracyanogen if ammonia be the only other 

 product. If, again, their paracyanogen were a product of the 

 decomposition of aqueous hydrocyanic acid, I am ready to 

 show that it was a low hydrate of paracyanogen, which I never 

 made any experiments upon ; but in such a case the burden 

 of proof lies on them. Moreover, howsoever the subject of 

 their experiments was prepared, (and in a matter affecting so 

 vital a truth or untruth as this is they ought surely to have 

 been more specific,) if it were not prepared exactly in the same 

 way as my own, their results can have no other relation to 

 mine than that of parallel lines, incapable of meeting and 

 merging indeed, but by no means diverging and contradic- 

 tory. Accordingly, nothing can be said of their experiments 

 till, at the middle of p. 299, they determine to avoid every ob- 

 jection by employing paracyanogen prepared from bicyanide 

 of mercury, and make one with what seems to be the substance 

 I used ; one experiment. 



Here I find no sufficient evidence in the single sentence, 

 in which the authors describe the preliminary process and 

 its product, that the former was rightly performed, or that 



* Philosophical Magazine, Oct. 1841, p. 295. 



