2io EGYPTIAN AGRICULTURE. 



SULPHATE OF AMMONIA. 



This manure is a waste product from certain industries 

 in the working of which nitrogenous organic matters, or 

 mineral matters containing a certain amount of nitro- 

 genous organic matter, are subjected to destructive distil- 

 lation. It therefore merits the name "artificial" to a 

 greater extent than nitrate of soda which, as has just 

 been shown, is a purified natural deposit. 



Nature. Sulphate of ammonia or more correctly 

 ammonium sulphate [(NH 4 ) 2 SOJ, when pure, is a white 

 crystalline salt without water of crystallisation. It is very 

 soluble though not quite so soluble as nitrate of soda, 

 one part dissolving in two parts of water at ordinary 

 temperatures. The commercial article is usually somewhat 

 coloured, the colour varying with the nature and amount 

 of impurity, but most samples have a greyish appearance. 

 The pure salt contains 2o'7o% ammonia, equal to 2l'2l% 

 nitrogen. Commercial sulphate averages about 24J % 

 ammonia, equal to 20'2 % nitrogen. The pure salt is 

 completely volatilised on heating, so adulteration of the 

 stuff by admixture with any non-volatile salt or substance 

 is easily detected. As a general rule the only impurities 

 likely to be present are moisture, free sulphuric acid and 

 perhaps a little insoluble matter. Formerly ammonium 

 thiocyanate (sulphccyanide) was occasionally met with 

 but sulphate as now prepared rarely contains even a trace 

 of this impurity. As thiocyanate is excee.lingly injurious 

 to plant life its presence is highly objectionable. It is 

 detected, however, by the addition of a few drops 



