STALL-MANURE AND STRAW. 137 



liquid pumped upon the muck-heap evaporate, and 

 the subsequent expenditure of labor is considerably- 

 reduced, inasmuch as then the water of the drain- 

 ings needs not to be carted, but merely the elements 

 of manure. 



4th. Care must be taken that the manure lies closely 

 packed^ in order that the air may not drive through 

 and desiccate it too strongly, as is the case when it 

 is piled but loosely. This is, perhaps, attained most 

 simply by letting out the cattle from time to time 

 upon the heap ; they will soon tread down its masses, 

 and render them sufficiently compact. 



5th. The volatilization of valuable elements^ more 

 especially of ammonia^ from the dung-heap^ should be 

 carefully prevented. Whenever a dunghill diffuses 

 an odor, or, in plain English, stinks, it is a certain 

 token that volatile and powerfully manuring sub- 

 stances are escaping from it. A good farmer will 

 exert himself to retain these substances on his prem- 

 ises, and, what is more to the purpose, on his muck- 

 heap. Porous bodies have the capability of absorb- 

 ing and firmly holding ammonia. Coating over the 

 manure with earth, especially with such as con- 

 tains humus acids (that is, moor-earth, peat, and 

 earthy brown-coal), seems, therefore, very proper 

 for this object. To scatter gypsum or ashes, which 

 contain this body (for example, the ashes of turf 

 or brown-coal), over the manure, is also service- 

 able ; inasmuch as sulphuric acid is present in the 

 gypsum, which has the power of fixing ammonia 

 12* 



