58 MANUFACTURE OF FERTILIZING MATERIALS 



position: sodium nitrate 96.75 per cent; sodium 

 chloride 0.75 per cent; sodium sulphate 0.30 per 

 cent; insoluble matter 0.10 per cent; water 2.10 

 per cent. 



Organic Nitrogenous Materials. Dried blood 

 obtained from slaughter-houses is a type of these. 

 It contains from 9 to 12 per cent nitrogen. 

 Ground hoofs and horns form another manure 

 of this class, as also waste woolen material, 

 such as shoddy running from 5 to 8 per cent 

 nitrogen. 



Potash. Potash, a necessary constituent of 

 plant food, has been supplied mainly as one or 

 the other of the products obtained in the Stass- 

 furt mining industry of Germany. The chief 

 salts are kainit, containing 12 to 14 per cent of 

 potassium oxide; the double sulphate of potas- 

 sium and magnesium, containing 27 to 28 per 

 cent potassium oxide, which is obtained from 

 kainit; carnalite with about 11 per cent of potas- 

 sium oxide in the crude mineral; and crude 

 potassium chloride of a strength corresponding 

 to about 50 per cent potassium oxide. Magne- 

 sium salts and chlorides detract to some extent 

 from the manurial value of these substances. 



Guano. This is the excrement of sea birds in 

 a more or less altered condition. A distinction is 

 drawn between nitrogenous and phosphatic gua- 

 nos; the former are either of recent origin, or have 

 not been subjected to weathering which is the case 

 in such dry climates as that of Peru; the latter 



