719 



nitrogenous matter. Ammonia is principally obtained from the 

 destructive distillation of some organic matter, as in the manufac- 

 ture of gas from coal, when it is obtained as a by-product in the 

 witer used to purify the gas. The gas liquor contains from f nr to 

 eight ounces of ammonia per gallon. The crude gas liquor is 

 placed in a large boiler with some burnt lime, and heated by HUMUS 

 of steam to drive oft" the ammonia gas, which is passed into a tank 

 containing sulphuric acid. The ammonia combines with the sul- 

 phuric acid to form sulphate of ammonia, which crystallises out, the 

 crystals being ladled out of the tank on to a shelf to drain, where 

 they are dried, and the mass is then ready for the market. Large 

 quantities are also obtained in the process of manufacturing shale 

 oil by the Beilby- Young furnace ; from blast furnaces, coke ovens, 

 and also in the process of manufacturing bone charcoal. Sulphate 

 of ammonia, when pure, contains 25 per cent, of ammonia. The 

 best sulphate of ammonia found in commerce contains only 98 per 

 cent., equal to 24^5 per cent, of ammonia. Sulphate of ammonia is 

 a whitish crystalline powder, some samples being colored grey to a 

 dirty brown. These latter samples should be tested for impurities, 

 such as ammonium sulpho-cyanate, which is very poisonous to 

 plants. This can be easily detected in a sample by dissolving a 

 little in water, then adding one or two drops of ferric chloride, 

 when, it the sulpho-cyanate is present it will give a deep red color 

 to the solution of ammonium sulphate. 



It has its best action on clay and loam soils, but should not be 

 used on soils rich in lime or otherwise, there will be a loss of 

 ammonia through its being set free by the lime. It should not be 

 used in a mixture with basic slag or Thomas's phosphates for the 

 same reason. 



The ammonia in the sulphate is not absorbed directly by the 

 plants. It is first converted into nitric acid in the process of 

 nitrification by the micro-organisms in the soil, in which state it is 

 absorbed by the plant. It is more easily converted into nitrates 

 than any other organic compound of nitrogen. In about six 

 months the most of the ammonia will be converted into nitrates. It 

 is easily fixed in the soil, which prevents the loss by drainage that 

 takes place in the case of nitrates, nor is it carried down into the 

 sub-soil out of the reach of the crops, as happens with nitrates. 



Its application to cereals, potatoes, and other root crops has 

 been very successful, but not so with rye, lupins, or leguminous 

 crops. 



Sulphate of ammonia is very seldom used by itself, being 

 generally employed in conjunction \vith phosphates and potash. 

 For cereals I to i^ cvvt., and for root crops from i^ to 2\ cwt. per 

 acre should be applied. It is best to use one-half "at the time of 

 sowing and to use the other half as a top dressing when the young 

 crop is a short length up, and the application should be made in 

 wet weather when possible. When sowing it alone as a top 



