Nitrate of Soda as a Manure. 



381 



On the other hand, great fault has been found with our ordi- 

 nary mode of making dung by laying it up in heaps. It has 

 been said that when first put together these heaps show the pre- 

 sence of Ammonia by the pungent smell that escapes from them, 

 but that after a few months their scentless state proves them to 

 have become little better than dead woody fibre. Still it was 

 clear that this apparently inert matter, though it gave forth no 

 odours, had a powerful effect upon the farmer's crops, and I have 

 long suspected that dunghills might contain Nitre. Mr. Nesbitt 

 informs me that by chemical analysis he has repeatedly found 

 nitrates in ripened dung. The alkali required might be furnished, 

 by the potash of the decayed straw. But he has also found, 

 what is a very curious chemical fact, that whereas, for forming 

 a salt, some alkali or other is required to combine with the acid, 

 and whereas further. Nitrogen, when liberated from decomposing 

 matter, may become either Nitric acid or Ammonia, which is 

 an alkali, both Nitric acid and Ammonia are in fact sometimes 

 formed in fermenting manure at the same time, for the very pur- 

 pose, as it were, of combination ; for Mr. Nesbitt finds Nitrate 

 of Ammonia* in dung-heaps. This is certainly a remarkable 

 effort of nature to prevent waste of fertilizing materials, but a 

 lesson which in our domestic arrangements w^e can hardly be 

 said to obey. 



Again, no farming practice has been more decidedly blamed 

 than the west country method of mixing lime with the dunghill, 

 because lime decomposes salts of ammonia. It was forgotten, 

 however, that in fresh dung the ammonia is not yet formed^ while 

 the undeveloped nitrogenous matter contained in the dung may be 

 most effectually fixed by the lime — -may become nitrified through 

 the mixture, exactly as in the French nitre-beds, by which salt- 

 petre was produced during the late war for the manufacture of 

 gunpowder."!* So cautious must we be in drawing chemical infer- 

 ences for farmers without careful and direct experiment. 



In compost heaps, too, nitrates are doubtless produced, and 

 the suggestion of Mr. Nesbitt is well worth consideration, that 

 in making our dung we should no longer aim at fixing ammonia, 

 which eludes our grasp, but at forming nitrates in accordance 

 with the practice of husbandry and the explanations of science. 

 Dr. Voelcker's opinions point the same way, and, in justice ta 

 him, his views ought to be presented as communicated to me 

 for my own information. 



evidently not a manure which can be adopted anywhere without previous trial, to- 

 be used upon the surface of land. 



* See Mr. Nesbitt' s letter appended to this paper. 



t According to the prevalent opinion caustic lime would decompose the urea 

 contained in fresh manure, but Dr. Voelcker informs me that experiment leads- 

 him to an opposite conclusion. 



