MODERN HIGH FARMING. 61 



NITRATE OF POTASH, commonly called saltpetre, is industrially 

 produced by the double decomposition, resulting from a mixture of 

 nitrate of soda and muriate of potash, with the application of heat. 

 Commercial saltpetre contains 10 to 12 per cent of nitrogen and from 

 40 to 44 per cent, of potash. 



It is soluble in three times its weight of water at an ordinary 

 temperature. 



MURIATE OP POTASH is, as we have already pointed out, the best 

 form in which to introduce potash, either directly into the soil, or 

 as a constituent in a compound manure. 



When freed from its chloride of sodium, sulphate and chloride of 

 magnesia, which always accompany it, the salt contains from 45 to 

 48 per cent, of pure potash. 



It is soluble in five times its weight of water, and has a salt and 

 bitter taste. 



PHOSPHATE OP LIME. The most readily accessible materials for 

 consumption in the United States, are the phosphorites of Charles- 

 ton, South Carolina, and the apatites, or crystallized phosphates, of 

 Canada. 



The phosphorites of the Charleston basin occur in the form 

 of nodules, bedded in the clay and sand. They cover an immense 

 area, and are found in detached deposits, at irregular intervals, all 

 along the water-courses of the country ; through the swamps and 

 on the banks of the rivers and streams. 



They are generally irregular iri form and color, being partially 

 rounded by the action of water, and of a yellow, green, or brown ; 

 while fossilized remains of fish are always, more or less, intimately 

 mixed up with them. 



They are distinguished in commerce by the names, Land and 

 River phosphates the first being the softest and lightest colored. 



They are dug up and submitted to a washing process, which 

 frees them from nearly all the sand and clay, and when thoroughly 

 uiicd after this operation, are ready for grinding, and present the 

 following average composition : 



