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XXXVI. Account of a Repetition of several of Dr Samuel Brown's Processes for 

 the Conversion of Carbon into Silicon. By GEORGE WILSON, M.D., and JOHN 

 CROMBIE BROWN, Esq. Communicated by the Secretary. 



(Read April 1. 1844.) 



THE object of the following paper is to lay before the Royal Society the re- 

 sults of a repetition of several of Dr SAMUEL BROWN'S processes for the conversion 

 of carbon into silicon. The greater number of these processes were published in the 

 Society's Transactions for 1840-41 ; and certain additional ones have since appeared 

 in a separate form. The latter were much simpler, and more readily performed, 

 than those made public at an earlier period ; and to one of these we first directed 

 our attention. 



Before stating, however, the results of any of our trials, we think it right to 

 mention, that most of the experiments which we now place on record, were regarded 

 at the time of their performance as only tentative and preliminary, and were not 

 registered with the minuteness of detail they would have been, had we expected 

 ultimately to publish them. 



We tried the greater number of Dr BROWN'S processes, and rejected them 

 one after another, without pursuing their investigation farther, on finding they 

 would not yield quantitative proofs of the conversion of carbon into silicon. The 

 limited time which, from various circumstances, we could devote to the subject, 

 obliged us to follow this course ; and the confident expectation we entertained, till 

 a recent period, that each new process would supply what the rejected ones had 

 failed to afford, led us to neglect noting many particulars of our early trials, which 

 otherwise we should have recorded. 



For the sake of brevity we leave unnoticed many subsidiary points connected 

 with our experiments, and restrict ourselves solely to those which bear upon the 

 question of an anomalous production of silicon, and the source whence it was de- 

 rived. 



We commence with the account of our repetition of the process for the pro- 

 duction of silicon from the cyanide of lead. This had the great advantage over 

 most of the others, that it yielded the silicon uncombined, and not, as they did, in 

 combination with oxygen as silica. It consisted in enclosing the cyanide in a 

 glass tube shut at one end, and drawn out at the other into a capillary. Heat 

 was then to be cautiously applied, and ultimately raised as high as was compatible 

 with the glass remaining unfused. Treated in this manner with the precautions 



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