CHEMICAL, MANURES. 95 



In a practical point of view, this indication is of great importance. 

 It teaches us that in such a soil we may have temporary recourse to 

 incomplete fertilizers, and can manure alternately, limiting ourselves 

 to the dominants, which allows us to obtain the maximum product 

 with small expense. 



DICTIONAKY OF CHEMICAL FERTILIZEKS. 



Azotic Matters. 



We designate under this name products of animal and vegetable 

 origin, of which azote forms a part : 



The blood, Albumen, 



Scrapings of horn, Scraps of wool, 



Muscular flesh, Litter, 



% Cakes. 



These are azotic matter. To act upon vegetation the substances 

 called azotic ' matter ought to be allowed to decompose in the soil ; 

 without this previous decomposition they have no action on plants. 

 When azotic substances are decomposed a part of their azote takes 

 the form of ammonia or nitrate. For this reason we include in the 

 class of azotic substances proper to agriculture 

 Sulphate of ammonia. 

 Nitrate of potash. 

 Nitrate of soda. 



These substances, which are true salts, contain azote to the number 

 of their constituents ; in sulphate of ammonia the azote belongs to 

 the ammonia, which is the base of salt; in the nitrate >of potash and 

 soda, the azote belongs to the acid of salt. 



Sulphate of Ammonia. 

 This salt is formed of sulphuric acid and ammonia : 



Sulphuric acid 60.60 



Ammonia 25.76 



Water.. 13.64 



100.00 

 Now, as the ammonia is in its turn formed of 



Azote 14 



Hydrogen 3 



17 



it results that the sulphate of ammonia contains 21.21 per cent of 

 azote .when chemically pure. That of commerce contains at most 

 20 per cent. Ammonia is drawn from the waters of sewers which 

 have been used for cleaning out cities. It is also obtained from the 

 distillation of coal employed in making coke and gas ; but the source 

 which surpasses all others is that offered by volcanoes, when they 

 become so quiet that they only throw off the vapor of water. 

 In 1866 sulphate of ammonia was worth 86.65 the 200 pounds. 



