HOW NITER IS FORMED IN THE SOIL. 67 



of what his crops need, he is the gainer by so much, and 

 by his abundant provision in the form of manure and fer- 

 tilizers, his fields are yearly increasing in fertility. The 

 formation of nitric acid and nitrates in the soil by the ac- 

 tion of the special ferment alluded to is of paramount im- 

 portance to the farmer. The manner by which this result 

 may be produced artificially, and has been effected for the 

 production of saltpeter, is as follows. A mass of soil rich 

 in organic nitrogenous compounds, as urine, animal excre- 

 ments, vegetable and animal matter of any kind, is put in- 

 to a heap and mixed with a quantity of quicklime. The 

 heap is put up loosely so that the air can penetrate easily 

 through the mass. In course of time the mass is leached, 

 and the liquid, highly charged with nitric acid, is neutral- 

 ized with carbonate of potash; the solution is then evapor- 

 ated and nitrate of potash or saltpeter is produced. These 

 heaps are known as "niter beds" and the process was for- 

 merly used extensively for procuring saltpeter for the man- 

 ufacture of gunpowder for warlike purposes, before the 

 great natural deposits of niter in South America were dis- 

 covered. These natural deposits are now the chief source 

 whence saltpeter of commerce is procured, and yield thou- 

 sands of tons yearly of nitrate of soda for use as a fertilizer. 

 It is a probable supposition that the origin of these deposits 

 was similar to that of the artificial niter beds. A vast mass 

 of organic matter rich in nitrogen, such as fish, or plants of 

 some kind, had accumulated in shallow lagoons of the 

 ocean, and had been covered with mud by gradual deposition. 

 The action of the atmosphere in the hot arid climate of 

 Western South America favored the nitrification of the mass 

 and the nitric acid formed, combined with the soda of the 

 salt from the sea water to form nitrate of soda. One of the 

 frequent convulsions of nature common to that coast eleva- 

 ted the surface of the land, gradually, during the formation 

 of the deposit, and the gradual rise has left the niter beds 

 in their present position at a distance from the ocean. The 

 compost heaps made by the farmer, in such a manner as to 

 favor this process of nitrification, form a source whence a 



