107 



solid substance, soluble, and not volatile. I have lately used 

 several cwts. of acid for this purpose, procured from my 

 friend, Mr. Charles Norris, who manufactures it at his exten- 

 sive chemical works at Sowerby Bridge. In order the better 

 to distribute the acid, I caused it to be diluted with four or five 

 times its weight of water, and periodically applied it to the 

 manure; with what effect remains yet to be seen, although I 

 can have no doubt of its beneficial result. The application 

 of sulphuric acid being an expensive process, I afterwards 

 adopted another suggestion derived from the same source, 

 and used Gypsum or Sulphate of Lime to eff'ect the purpose. 

 Gypsum when burnt or baked, in order to drive off the water 

 of crystallization, contains about 58 per cent of sulphuric 

 acid ; therefore in applying two tons of this substance, costing 

 about £5, you, in effect, apply rather more than one ton of 

 the acid, which from the chemist would cost about £11. 

 This application of gypsum must depend, for its utility, on 

 the correctness of the following theory, namely, that the sul- 

 phuric acid of the gypsum has a greater affinity for ammonia 

 than for the lime with which it is combined, and that it will 

 leave the lime and cling to the ammonia, forming sulphate of 

 ammonia and carbonate of lime. The following diagram will 

 exhibit this chemical process : — 



r'TT^o,,,^. f Sulphuric Acid\ 



^^P^^""" ^ Lime Carbonate of Lime. 



Carbonate J Carbonic Acid " \^ 

 of Ammonia. (Ammonia Sulphate of Ammonia. 



To satisfy myself on this point, I mixed together, in a state 

 of powder, a small quantity of gypsum and carbonate of am- 

 monia, at the same time applying a little moisture, and a gentle 

 heat. For two or three hours the volatility of the ammonia, 

 evident from its pungent smell, continued still very perceptible; 

 but in the course of a day it became less apparent, until at last 

 all the peculiar pungency of smell ceased. To ascertain 



