USE OF SULPHATE OF AMMONIA. 34D 



results precisely ascertained, it would be improper to incur much risk 

 either in bringing this substance to our shores or in applying it to our 

 fields. 



10°. Silicates of Potash and Soda. — These compounds, which have 

 been already described (p. 206), are supposed to act an important 

 part in the growth of the grasses, and of the corn-bearing plants, by 

 supplying, in a soluble state to the roots, the silica which is so necessary 

 to the strength of their stems. This supposition has been strengthened 

 by the results of some experiments made by Lampadius, who found a 

 solution of silicate of potash to produce remarkable effects upon Indian 

 corn and upon rye. {Lehre von den mineralischen Dungmitteln, p. 25, 

 1833.) It is possible to manufacture them at a cheap rate, and it would 

 be desirable to ascertain by further trials how far the employipent of 

 these compounds, as artificial manures, can be safely recommended or 

 adopted with the hope of remuneration.* 



11°. Salts of Ammonia, — There is reason tobelieve that ammonia in 

 every state of combination is fitted, in a greater or less degree, to pro- 

 mote the growth of cultivated plants. None of its compounds, how- 

 ever, are known to occur anywhere in nature in such quantity as to be 

 directly available in practical agriculture, and only a very few can be 

 produced by art at so low a price as to admit of their being used with 

 profit. 



a. Sulphate of Ammonia. — An impure sulphate is manufactured by 

 adding sulphuric acid to fermented urine, or to the ammoniacal liquor 

 of the gas works, and evaporating to dryness. When prepared from 

 urine, it contains a mixture of those phosphates which exist in urine, 

 and which ought to render it more valuable as a manure. The gas 

 liquor yields a sulphate which is blackened ^y coal tar — a substance 

 which, while not injurious to vegetation, is said to be noxious to the 

 insects that infest our corn fields. In any of these economical forms this 

 salt has been found to promote vegetation ; but accurate experiments 

 are yet wanting to show in what way it acts — whether in promoting the 

 growth of the green parts or in filling the ear, or in both — to what kind 

 ol" crops it may be applied with the greatest advantage — and what 

 amount of increase may be expected from the application of a given 

 weight of the salt. It is from the rigorous .determination of such points 

 that I he practical farmer will be able to deduce the soundest practical 

 precepts, and at the same time to assist most in the advancement of 

 theoretical agriculture. 



The crystallized sulphate of ammonia is soluble in its own weight of 

 water. 100 lbs. contain about 35 lbs. of ammonia, 53 lbs. of acid, and 

 1 2 lbs. of water. It may be applied at the rate of from 30 lbs. to 60 lbs. 

 per acre. 



b. Sal- Ammoniac or Muriate of Ammonia. — This salt, in the pure 

 state in which it is sold in the shops, is too high in price to be economi- 

 cally employed by the practical farmer. An impure salt might, how- 

 ever, be prepared from the gas liquor, which could be sold at a sufficiently 



• I have been informed by Dr. Playfair that a number of experiments with a soluble 

 silicate of soda, manufactured at Manchester, have this summer (1842) been made at his 

 suggestion, the results of which will, no doubt, prove very interesting. 



