316 EEPORT ON NITRIFICATION. 



nese in this way for the purpose of supplying saltpetre in the event 

 that France should be engaged in a war which should cut her off 

 from foreign sources of this necessary article. Other substances, 

 deutoxide of barium, &c., have the same property with dcutoxide of 

 manganese. 



There is one body which has been found to have remarkable power 

 in bringing about the oxidation of ammonia, the precise mode of 

 whose action may be a little doubtful. According to the experiments 

 of Mr. Ashe, when the vapor of ammonia, mixed with air, comes 

 into contact with freshly-prepared sesquioxide of chromium, it under- 

 goes such rapid oxidation that the oxide glows and remains red hot 

 until the ammonia is consumed. This takes place not only with am- 

 monia, but with many other combustible vapors.* 



Mr. Ashe supposes the rationale of this action of the chrome oxide 

 to be the same as in the similar case of spongy platinum — to depend, 

 in other words, upon the physical condition of great porosity, and 

 this is, undoubtedly, the main cause, but possibly the chrome acts 

 also as a carrier of oxygen by passing alternately from a higher to a 

 lower degree of oxidation. However that may be, this employment 

 of the oxide of chromium deserves attention, as promising to furnish 

 a most excellent mode of nitrification. 



The second mode of producing nitrates (by the combination of the 

 elements of the atmosphere) is one which has experimentally been 

 shown to be possible, and which probably goes on upon a large scale 

 in nature in conjunction with the first-mentioned method. The 

 economy of a manufacture based on this mode, if it could be brought 

 into extensive operation, is very appare^nt; but the subject has been 

 so imperfectly investigated as yet, that what could be said upon its 

 feasibility would be merely conjectural. 



V. The fifth and concluding branch of the topic is this: By what 

 means may experimental science, best be advanced in regard to the 

 subject of nitrification ? 



It must strike every one that, considering the importance of the 

 subject and the length of time during which an interest has been felt 

 in it, our actual knowledge of it is remarkably limited. Dumas re- 

 marks, in this connexion, that such a length of time and so much 

 trouble would be required to watch the process as it goes on in nitre 

 beds, that no one has had the courage to undertake it; and the same 

 thing holds, to a gr^at extent, with regard to the study of nitrifica- 

 tion under any aspect. Within the last twenty-five years experi- 

 ments have been made from time to time that have thrown light on 

 particular points; and occasional observations upon the natural pro- 

 duction of nitre have given us something to build conjecture upon, 

 but inquiries of either kind have generally not been pushed beyond 

 the isolated fact in which they began, but have stopped after show- 

 ing that a nitrate might be generated in some particular way, or 

 describing some locality in which it was found. Even such contribu- 



« Lond. Ed. and Dub. Ph. Jour., 1853. 



