

THE COMPOST HEAP. 



77 



began. The result was that nitrates were formed in the interior of 

 the heap in large quantity. Eventually the nitrates were extracted 

 by water and converted into nitrate of potassium by the addition of 

 some potassium salt. 



This method of making saltpeter was discovered before science 

 had any idea of the real nature of the process, and it was a practical 

 means of utilizing a part of the nitrogen in the organic substances 

 derived from animals and plants. Whether it was the most efficient 

 means or more useful than the simple compost heap and manure 

 pile can hardly be stated. 



Saltpeter plantations have gone out of existence since the in- 

 troduction of Chilian saltpeter. It is probable that the nitrate beds 

 of Chili are the remains of some old inland arms of the sea where 

 great growths of seaweeds accumulated which, after the drying of 

 the inland sea, were converted into nitrates by the processes of 

 decomposition and nitrification due to bacterial action. 



Nitrates are formed upon the walls of closets and stables where 

 ammonia fumes are abundant. On such walls may frequently be 

 seen a snow-white mass consisting of calcium nitrate. It is the result 

 of nitrification of the ammonia which unites with oxygen and pro- 

 duces nitric acid. The acid combines with the calcium present in 

 the brick- work to form calcium nitrate. The action is an undesirable 

 one from the standpoint of the persistence of the walls, since it pro- 

 duces a corroding action tending to weaken the structure. It may 

 be readily prevented by sprinkling the walls with a strong solution of 

 some powerful antiseptic, such as formalin or corrosive sublimate. 



THE COMPOST HEAP. 



It is evident that in a compost heap there must be going on a 

 series of similar bacterial transformations. By proper means the 

 farmer may make use in his soil of almost any organic material 

 which contains nitrogen or the minerals needed for his crops. 

 Vegetable tissues of all sorts contain more or less nitrogen and may 

 readily be brought under the influence of the bacteria which are 

 able to reduce them to plant foods. A valuable source of such 



