NITRATE OF VODA. 117 



of these 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 

 brought away by the shipload, and may be obtained at 

 such prices as would warrant the application of it in 

 moderate 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 obtained, or refuse liquid in which it 

 has been dissolved for pickling meat, etc., it should be 

 mixed into a compost heap, and carefully preserved. 



There are several compounds containing sulphuric 

 acid, called sulphates, that are also valuable whenever 

 they can be had at reasonable prices. Those that 

 have been most commonly employed, are the sulphates 

 of nagnesia and of soda. From their composition, 

 both of these must be useful; but it would be necessary 

 to exercise a degree of caution with the sulphate of 

 magnesia, as it is very soluble, and much of it might 

 do harm. It will be remembered that magnesia in 

 any large quantity is quite injurious in the soil : small 

 quantities are very useful. 



The refuse liquid from salt-works after the salt has 

 been crystallized out, contains some soluble compounds 

 of lime, magnesia, etc., and might, applied carefully 



