THE MANURE HEAP AND SEWAGE. I I/ 



heap, then, the farmer may throw all sorts of organic debris, 

 animal or vegetable, with the confidence that his bacterial aids 

 will in time place the nitrogenous material in some measure at 

 his service as a fertilizer. Thus, by the aid of his invisible 

 allies the agriculturist will be able to make use of the wastes 

 on his farm and in time return to his soil a considerable por- 

 tion of the nitrogen therein. 



It is quite certain that the future study of the conditions 

 under which these various bacteria will best act will result in 

 such modifications of farm processes as will produce a consid- 

 erable saving of the nitrogen which has been allowed to go to 

 waste. Under proper conditions these organisms can certainly 

 furnish the soil with larger quantities of nitrogen than they 

 commonly do upon even the best farm. When he has them 

 under proper control the farmer can feel sure of making use of 

 all the available nitrogen present in the nitrogen wastes of his 

 land, and he may greatly reduce the loss of this element which 

 at present is going on through the dissipation of free nitrogen 

 and ammonia into the air. 



SALTPETER PLANTATIONS. 



These nitrifying forces are not confined to the soil, but may 

 occur in other localities, always resulting in the production of 

 nitrates. Before the discovery of the nitrate beds of South 

 America it was the custom of agriculturists to prepare their 

 own nitrates by a simple process, not then understood, but 

 now known to be due to nitrifying bacteria. The places where 

 nitrates were thus formed were called saltpeter plantations, and 

 the saltpeter was produced by exactly the processes we have 

 already considered. The method was as follows : 



Masses of chalky soil were mixed with various organic 

 bodies and the whole heaped into a pyramidal pile, rendered 

 somewhat porous by the admixture of brushwood. The heap 

 was still further furnished with fermentable nitrogen by fre- 



