318 IMPROVEMENT OF THE SOIL 



One hundred parts of the soluble, from hard wood, are 

 composed of 



Carbonic acid 22.70 I Potash and soda 67.G6 



Sulphuric acid 64^ 



Muriatic acid 1.82 \ 99.86 



Silex .!!5 I 



It will be perceived that the salts are not all carbonates, 

 although the greater proportion of them are. One hundred 

 parts of the insoluble portions contain 



Peat ashes contain carbonate, phosphate and sulphate of 

 lime. 



Ashes, then, are composed of salts and silicates ; they con- 

 tain potash, lime and soda, and their use depends upon the 

 action of these alkalies, which render them an efficient ma- 

 nure. Ashes are excellent for grass lands. One bushel of 

 ashes contains 5J lbs. of potash, a quantity sufficient to de- 

 compose 200 lbs. of peat earth. 



Leached ashes correspond to the insoluble portions, and 

 part of the lime is added, one peck of lime to a bushel of 

 ashes, to render the lye caustic by absorbing the carbonic 

 acid. Spent ashes, however, generally contain about 50 lbs. 

 of silicate of potash per cord, so that they act both by their 

 alkali and by their lime. Silicate of potash depends for its 

 action wholly upon being converted into the carbonate of 

 potash, and hence may be classed with the carbonates. 



When ashes are composted with peat, they form a cheap 

 and valuable manure; but should not be applied to the soil 

 in large quantities, unless vegetable matters are also added. 

 Ashes applied to light, dry soils, always act beneficially. On 

 wet soils, they sometimes introduce mosses. 



Barilla or white ash, may be classed as a carbonate ; its 

 has already been considered, p. 367. The latter may 



