No. 4.] BARNYARD MANURE. 305 



valuable nitrogen become soluble and volatile in the form of 

 ammonia, which is a gas. This gas is well known as "harts- 

 horn," and is easily recognized by its strong odor. It forms 

 very rapidly in the presence of a limited amount of moisture 

 and a somewhat elevated temperature. Urine is its principal 

 source, and next to that comes horse dung. 



It is very important that all this gaseous form of nitrogen 

 be saved, and whenever its odor is detected, means should 

 immediately be taken to "fix" or absorb it. No space con- 

 taining manure should be allowed to smell of ammonia. 

 Substances used for this purpose are : — 



Hydrochloric acid, which fumes strongly. 



Sulphuric acid, which does not fume, but corrodes every- 

 thing it touches, e.g., the hoofs of horses and cattle. 



Neither of the above should be employed. 



Green copperas is good, but it is also slightly corrosive, 

 and often injurious to crops. 



Gypsum or land plaster is excellent. 



Sulfate of magnesia is the same. It sometimes combines 

 with and holds the soluble phosphoric acid. 



These materials are sprinkled daily over the floor and 

 manure. 



Preservatives. — While the foregoing substances retain 

 the ammonia, they do not prevent fermentation. Sometimes 

 a farmer wishes to accomplish both of these ends. The fol- 

 lowing substances, when mixed with the manure, act in this 

 double way : — 



Sulfate of magnesia, or kieserite. 



Double sulfate of potash and magnesia. 



Carnallite and kainite, containing chloride of potash, salt, 

 sulfate of magnesia and chloride of magnesia. 



When these are used, account is taken of the addition of 

 potash to the manure. 



Charcoal and peat are also good fixers, and to an extent 

 preservatives. 



The finished manure from difierent animals shows very 

 different qualities : — 



Horse maiiure is the most uniform of all, because the 

 horse's food is the most uniform, and generally of the same 

 kind. It is a rich manure, and ferments quickly, producing 



