SECONDARY PRODUCTS. 203 



their propositions by the knowledge of the chemical changes that take place 

 during the process of vegetable generation. 



This liquor is applicable probably only to certain soils ; but those which 

 require the aid of sulphate of lime may certainly be further aided by uniting 

 with the gypsum a portion of the ammoniacal liquor, since it would fix the 

 alkali forming sulphate of ammonia, and render it more easily absorbable by 

 the ground on which it is laid. 



In many parts of Flanders, Belgium, and France, but particularly in China, 

 human urine is collected with great care for the purpose of manuring meadow 

 land and corn-fields. The barren soils on the coasts of South America are 

 manured with the excrement of a sea-bird very numerous in those parts, and 

 which consists of urate of ammonia and other ammoniacal salts ; and good 

 crops are produced. There are numerous instances of the same results being 

 produced all over the world, upon soil of almost every different variety ; and 

 ammoniacal liquor would have the same effect (if chemistry is to be believed) 

 as those substances just mentioned. 



I am convinced much good might be derived from different qualities of the 

 refuse products of gas-works as manure. An inquiry into this subject would 

 remunerate the engineer or agriculturist to the full, would besides confer a 

 considerable benefit upon his fellows, and give that practical proof of the cor- 

 rectness of a theory so welcome to the man of science. 



The above is comparatively a new application of the ammoniacal liquor ; it 

 has generally been used for the manufacture of the carbonate and muriate of 

 ammonia, and is the great source in this country from which the manufacturers 

 of the salts of ammonia obtain their supply ; so fruitful is it, that since the 

 manufacture of gas has become general, the price of muriate of ammonia, one 

 of the most useful of these salts, has been reduced to one-fifth of that at which 

 it was previously sold. 



The process usually adopted is the following : The salts contained in the 

 liquor are the sesquicarbonate and hydrosulphate of ammonia : the first object 

 is to reduce both to a sulphate, or by some, to a bisulphate, and then, by 

 sublimation with chalk or common salt, to procure the carbonate or muriate 

 of ammonia. 



The ammoniacal liquor is allowed to stand at rest for a few days, either in 

 cisterns or casks, in which it has been transported from the gas-works. The 

 heavy tarry matters subside, and the lighter collect on the surface, and are 



