338 Bacteria in Relation to Country Life 



in the production of niter in artificial niter-beds serves 

 to throw much light on the processes of nitrification in 

 manure. It was found by niter-refiners that certain 

 rules had to be observed for the profitable production 

 of niter. Provision had to be made for the proper circu- 

 lation of air in the niter-bed. This was accomplished by 

 separating the layers of earth mixed with organic 

 matter, by means of faggots or twigs. Nitrifiable or- 

 ganic matter was to be furnished, and was supplied 

 best by moistening the niter-bed with liquid excreta. 



Effect of liquid. It was learned here that there is a 

 limit to the quantity of liquid excreta that may be added 

 with safety. When that point was passed, nitrification 

 not only stopped, but there was an actual diminution in 

 the amount of nitrate that had already formed. Moisture 

 was needed in just the right proportion. With too much, 

 nitrification was suspended and reducing processes set 

 in. When nitrification was well under way, the propor- 

 tion of moisture that could be advantageously retained 

 in the niter-bed was still further reduced. 



In view of the foregoing facts, we can readily under- 

 stand that, everything being equal, a quantity of manure 

 rich in liquid excreta would begin to nitrify at a later 

 date than a similar quantity of manure poor in liquid 

 excreta. Similarly, a manure pile frequently drenched 

 by rain would not only lose its nitrates by leaching, 

 but, also, by reduction on account of the replacement of 

 the air in the interior of the heap by water. A small 

 proportion of carbonate of lime would favor the nitri- 

 fication processes in the manure by preventing the ac- 

 cumulation of acid substances injurious to the organisms. 



