VITBATE or SODA. 117 



of theie is the Nitrate of Soda. This is composed of 

 nitric acid (a substance before described) and soda. 

 The nitric acid contains much nitrogen, and is there- 

 fore very active as a manure. One or two cwt. nitrate 

 of soda have been found, in many instances, to produce 

 a very great growth. It gives a bright dark green color 

 to the leaves, and increases the yield of grain. It also 

 produces a marked improvement in grass crops and 

 pastures. Grain that has been grown by aid of this 

 manure is said not to give so much fine flour, being 

 richer in gluten, and having a thicker skin. 



Nitrate of soda is in some districts of South Ame- 

 rica a natural product, being found in a crust on the 

 surface of the ground; it is so abundant as to be 

 broucrht away by the shipload, and may be obtained at 

 s ' s as would warrant the application of it in 



II quantities. Other nitrates are manufactured 



which would be excellent manures, but the price is 

 generally so high as to forbid their use with profit 

 Whenever refuse nitrate of potash, that is, common 

 saltpetre, can be ol' ' >r refuse liquid in which it 

 has been dissolved mg meat, «le^ it i^onldbe 



mixed into a compo;»t htap, and carefully - — •(!. 



Thrrr are several compounds rontainii iric 



•1 sulphates, that are also valuable whenever 

 li.- , - ..:: be had at reasonjiMe prices. Those that 

 have been most coramo; yed, are the sulphates 



of magnesia and of sou.i. I torn their composition, 

 both of these must be u.seful ; but it would be necessary 

 to exercise a decree of caution with ' ' ' > of 



raa^iie-sia, as it is very snhihle, nnd n .;^ht 



do harm. It will be r hat magnesia in 



any large quantity is (] I, ^ in the soil: small 



quantities an- tul. 



The rpf""v' . ;.,>in salt-works after the salt has 



been cry^' it, contains some soluble coropouiMli 



of lime, magnesa, etc, and might, applied e uM lt f 



