134 TOBACCO LEAF. 



shows that, applied as previously directed, these organic 

 manures give up nitrogen to the crop as it can be used. 

 The value of nitrates is modified because nitrogen in 

 this very soluble form is so exposed to leaching. Jenkins 

 has "seen a heavy rain leach away the whole nitrogen 

 supply of a crop where it was in the form of nitrates." 

 It could not do this with organic forms. 



The consumption of t these nitrogen salts, especially 

 of nitrate of soda, is steadily increasing. There are 

 three of these crystalline salts : Nitrate of potash, which 

 is made by the union of nitric acid and potash ; sulphate 

 of ammonia, which is sulphuric acid combined with 

 ammonia, and nitrate of soda, a combination of nitric 

 acid and soda. Of these, the first, nitrate of potash, is 

 rarely used as a fertilizer. It is largely used in the 

 manufacture of gun powder, and commands such a price 

 as to prevent its use for fertilizing purposes. It would 

 seem to be admirably adapted to tobacco culture, owing 

 to its large percentage of both nitrogen and potash, 

 elements especially demanded by this crop, and it should 

 be tried experimentally. Nitrate of potash contains 

 about 14 per cent of nitrogen and 45 per cent of actual 

 potash. 



Sulphate of Ammonia. This valuable salt is ob- 

 tained in large quantities as a by-product in the man- 

 ufacture of illuminating gas. It is a white crystalline 

 salt having a slightly bluish tinge and may have a faint 

 odor of ammonia, but it usually is odorless. Its value 

 as an agricultural salt has long been known, and it is 

 largely used for manurial purposes, both in this country 

 and Europe. It is very uniform in composition, and is 

 sold under a guaranteed analysis of twenty-four to 

 twenty-five per cent of ammonia, which is the same as 

 twenty to twenty and one-half per cent of nitrogen. 

 The percentage of free water is very small, rarely over 

 one per cent. It is freely soluble in water, and the 



