Carbon^ Silicon, and Nitrogen. 15 



lous production ; and draws from the whole the following 

 conclusion: " From these experiments, together with those 

 of Sir H. Davy mentioned above, one might infer that nitro- 

 gen is either a compound of silicon and hydrogen, or of sili- 

 con, hydrogen, and oxygen ; to determine which synthetically, 

 a current of dry muriatic acid was passed over siliciuret of 

 potassium," and the resulting gases examined. These were 

 found to contain a variable but marked proportion of nitro- 

 gen ; so that, so far as can be judged from the imperfect ac- 

 count we possess, Mr Knox seems to consider nitrogen a com- 

 pound of silicon and hydrogen, and to believe that he formed 

 it by the action of muriatic acid on siliciuret of potassium. 

 He does not suppose, however, as some have imagined, that 

 the nitrogen is transmuted into silicon ; he believes that the 

 former yields, but not that it forms the latter, in the way 

 Dr Brown supposes that carbon forms silicon. Silicon, ac- 

 cording to Mr Knox, pre-exists in nitrogen, along with hydro- 

 gen, or with hydrogen and oxygen, by combination with 

 which it makes up the nitrogen. He supposes, accordingly, 

 that, in Dr Brown's experiments, the nitrogen was the 

 source of the silicon, and that the carbon was useful only 

 by combining with and removing the non-siliceous element 

 or elements of the nitrogen, and setting the silicon free; 

 and he endeavours to establish this by shewing, that if the 

 other conditions of Dr Brown's experiments were retained, 

 but the carbon replaced by a metal such as potassium (or 

 rather by potassium and iron), the production of silicon went 

 on as well as if carbon had been there. His view, there- 

 fore, has the advantage of explaining Dr Brown's results as 

 well as his own ; whereas that gentleman's theory afibrds no 

 explanation of Mr Knox's experiments.* The latter, moreover, 



* In so far as Dr Brown refers the silicon which appeared in his expe- 

 riments to carbon, his explanation will, of course, not apply to re- 

 searches like those of Mr Knox, where silicon was found, though no 

 carbon was present. He may fall back, however, on his general hypo- 

 thesis, that the higher elements are isomeric forms of the lowest, and 

 affirm that the hydrogen of the ammonia-nitruret of potassium was trans- 

 muted, mediately through carbon, or immediately into silicon. When 

 the text was written, I was not aware that Dr Brown had explained 



