306 EREMACAUSIS OR DECAY 



ascribe a new character to it, for the purpose of explaining a sin- 

 gle 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 exposed to the action of air, 

 water, and alkaline bases, possesses the power of combining 

 directly with oxygen, and of thus forming nitric acid ; but we 

 are not acquainted with a single fact which justifies this opinion. 

 It is only by the interposition of a large excess of hydrogen in 

 the state of combustion or oxidation, that nitrogen can be con- 

 verted into an oxide. 



When a compound of nitrogen and carbon, such as cyanogen, 

 is burned in oxygen gas, its carbon alone is oxidized ; and when 

 it is conducted over a metallic oxide heated to redness, an oxide 

 of nitrogen is very rarely produced, and never when the carbon 

 is in excess. Kuhlmann found in his experiments, 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 com- 

 bine directly with oxygen, even under the most favorable cir- 

 stances ; thus, with the aid of spongy platinum at different tem- 

 peratures, no union took place. 



The carbon in the cyanogen gas must, therefore, have given 

 rise to the combustion of the nitrogen by induction. 



On the other hand, we find that ammonia (a compound of hy- 

 drogen and nitrogen) cannot be exposed to the action of oxygen, 

 without the formation of an oxide of nitrogen, and production of 

 nitric acid, in consequence of this union. 



It is owing to the great facility with which ammonia is 

 converted into nitric acid, that it is so difficult to obtain a cor- 

 rect determination of the quantity of nitrogen in a compound 

 subjected to analysis, in which it is either contained in the form 

 of ammonia, or from which ammonia is formed by an elevation 

 of temperature. For when ammonia is passed over the red-hot 

 oxide of copper, it is converted, either completely or partially, 

 into binoxide of nitrogen. 



When ammoniacal gas is conducted over peroxide of manga- 



