Carbon, Silicon, and Nitrogen. 17 



appearance or production of silicon is concerned, we can authen- 

 ticate Dr Brown's results, but no further. Some misappre- 

 hension, I believe, exists on this subject, and I am anxious it 

 should continue no longer. I took the most public opportunity 

 that was open to me last autumn,* of declaring my confident 

 expectation, that a repetition of Dr Brown's processes would 

 establish the truth of his theory ; and I owe it to myself, still 

 more to those I induced by my representations to advocate his 

 cause, but above all to the interests of science, which must be 

 hindered in its progress by the confusion of doubtful with cer- 

 tain knowledge, to take as public an opportunity of saying, that 

 Dr Brown's processes have not, in my hands, yielded proof 

 of the transmutability of carbon into silicon. 1 have further 

 come to the conclusion, that they are too imperfect to establish 

 the truth of that proposition in the hands of any one ; and that 

 there exists at present no evidence, in the way of demonstra- 

 tion by experiment, to satisfy a chemist, that carbon or any 

 other element has ever suffered transmutation. 



A peculiar difficulty attends the reception of the proposition, 

 that carbon is transmutable into silicon ; a difficulty which to 

 many chemists seems insurmountable, and which has not been 

 provided for by Dr Brown in any of his papers, although he 

 was aware of its existence. It results from the irreconcila- 

 bility of the atomic weights of carbon and silicon, the former 

 of which is 6, the latter 2222. According to Dr Brown, an 

 atom of silicon consists of 4 atoms of carbon ; but four times 

 six is 24, not 22*22. If, therefore, transmutation by isomeric 

 synthesis of carbon into silicon occur, it must, according to this 

 view, be accompanied by a destruction of matter equal to the 

 difference between 24 and 22-22 ; or, for every 24 parts by 

 weight of carbon subjected to transmutation, only 22*22 of 

 silicon would be obtained. I did not allow this difficulty to 

 stand in the way of my repetition of the silicon experiments, 

 as I saw a way of overcoming it. I shall mention what this 

 was, without entering into any details in the way of vindication 



* In a letter to the Lord Provost of Edinburgh on Dr Brown's claims 

 to the Chair of Chemistry, which was printed and widely circulated, but 

 not published. 



VOL. XXXVII. NO. LXXIII. JULY 1844. B 



