PRACTICAL INFERENCES. 283 



dilution it may be of service to certain crops, not merely 

 by virtue of the ammonia, but also in consequence of the 

 sulphuretted hydrogen, which it contains, since the latter 

 is found to be an ingredient in the turnip, and in some 

 other tribes of cruciferous plants. 



"Where, however, it is found troublesome to preserve, 

 or difficult to convey to a distance this volatile material, an 

 easy method presents itself for retaining for any length of 

 time the ammonia present in it. 



*'This is done, by availing ourselves of the same prin- 

 ciple which has been already explained to you, in treating 

 of the uses of gypsum as a manure ; for as the gas liquor 

 consists of ammonia, combined principally with carbonic 

 acid, it is evident, that it may be converted into a sulphate 

 by admixture with sulphate of lime. 



*'I am indebted to an excellent scientific chemist^ for 

 the following details, which may be of use to the agricul- 

 turist in enabling him to appreciate the importance of this 

 commodity, and to prepare for himself any quantity that he 

 may require for his farm. 



"One gallon of the ammoniacal liquor added to 1 lb. 2-| 

 ozs. of powdered but not calcined gypsum, will produce 

 1 lb. of crystallized sulphate of ammonia. To effect the 

 decomposition, the materials should be mixed and stirred 

 up together for ten or twelve hours, a heat, below that of 

 ebullition, being at the same time employed. The sulphate 

 of ammonia remains in solution, and may be obtained in a 

 solid state, by evaporating at a low temperature. 



"Theory would suggest, that this material ought to sup- 

 ply nitrogen to the crop at a much cheaper rate than the 

 nitrates employed for that purpose. For let us suppose, 

 that the farmer wishes to add to his land 60 lbs. of crys- 

 tallized sulphate of ammonia. This may be obtained by 

 introducing about 70 lbs. of powdered gypsum uncalcined 

 into 50 gallons of ammoniacal liquor ; for my informant 

 found, that one gallon mixed with chloride of calcium 

 yielded 4800 grs. of carbonate of lime, equivalent to about 

 7200 grs. of crystallized sulphate of ammonia, or 1 lb. 3 

 ozs. Now 4800 grs. of carbonate of lime are equivalent 

 to 8250 grs., or to 1 lb. 5 ozs. of sulphate of lime, with 2 

 atoms of water. 



"This, therefore, is the quantity of gypsum required, to 



" * Mr. Richard Phillips, the superintendent of the chemical depart- 

 ment of the establishment, connected with the Museum of Economic 

 Geology, lately instituted by government." 



