278 EREMACAUSIS OR DECAY 



racter to it, for the purpose of explaining a single 

 phenomenon, especially where the explanation of 

 that according to known facts offers no difficulty. 



The most distinguished philosophers suppose 

 that the nitrogen in an animal substance, when ex- 

 posed to the action of air, water, and alkaline bases, 

 obtains the power to unite directly with oxygen, 

 and form nitric acid, but we are not acquainted 

 with a single fact which justifies this opinion. It 

 is only by the interposition of a large quantity of 

 hydrogen in the state of combustion or oxidation, 

 that nitrogen can be converted into an oxide. 



When a compound of nitrogen and carbon, such 

 as cyanogen, is burned in oxygen gas, its carbon 

 alone is oxidised ; and when it is conducted over a 

 metallic oxide heated to redness^ an oxide of nitro- 

 gen is very rarely produced, and never when the 

 carbon is in excess. 'Kuhlmann found in his ex- 

 periments, that it was only when cyanogen was 

 mixed with an excess of oxygen gas, and conducted 

 over spongy platinum, that nitric acid was gene- 

 rated. 



Kuhlmann could not succeed in causing pure 

 nitrogen to combine directly with oxygen, even 

 under the most favourable circumstances ; thus, with 

 the aid of spongy platinum at different tempera- 

 tures, 'no union took place. 



The carbon in the cyanogen gas must, there- 

 fore, have given rise to the combustion of the ni- 

 trogen by induction. 



