186 COMPOSITION OF CARBONATE, SULPHATE, 



Water absorbs from 400 to nearly 700 times its bulk of this 

 gas, acquiring, at the same time, all the sensible properties of 

 the gas. The common hartshorn of the shops is such a solution 

 of ammonia in water. 



The salts of ammonia which have been, or are likely to be, 

 employed either with advantage in practical agriculture, or 

 with the prospect of interesting theoretical results are the 

 carbonate, the sulphate, the muriate, the nitrate^ the phosphate, 

 the acetate, the oxalate, and the humate. 



These salts are composed as follows, 



1. Carbonate of ammonia of ) , j C * tb acid > *! 



Al , > consists of < Ammonia, 55.9 



thesh P S ' ' j (Water, . 15.3 



100 



This salt gives off ammonia when exposed to the air ; hence 

 the powerful odour to which it owes the name of smelling-salts. 

 In consequence of this property, it seldom contains so much am- 

 monia as the above numbers represent. When it ceases to give 

 off this strong smell, it contains only 21^ per cent of ammonia. 

 It is then what chemists call fo-carbonate, the pure smelling- 

 salts being sesg7-carbonate of ammonia. 'When dissolved in 

 water, on the other hand, as it is in ammoniacal liquor, it loses 

 carbonic acid, and becomes what is called the neutral carbonate, 

 which contains 39 per cent of ammonia. 



This salt of ammonia, therefore, is of inconstant composition, 

 and, consequently, is not well adapted for accurate field experi- 

 ments. 



00 c -, , . . . . ) ( Sulphuric acid, 60.6 



2. Sulphate of ammonia m I c I An) P moni 25Q 



dry crystals . J (***, . 13.6 



100 



This salt is without smell, and, when pure, is constant in 

 composition. 



3. Muriate of ammonia, or ) f Muriatic acid, 68.2 



> consists of < A 

 sal-ammoniac, . j [ Ammonia, 31.8 



100 



