MODERN HIGH FARMING. 05 



If the use of chemical immures is to become a universal institu- 

 UOQ and a "thing of course," they must be placed within reach of 

 consumers, at the lowest possible price ; because, were the main- 

 tenance or increase in the quantity and quality of our crops to be 

 simply counterbalanced by the cost of the fertilizers, no ultimate ad- 

 vantage could accrue from their application. 



The mixture of finely powdered raw phosphates with farm-yard 

 manures, in a manner similar to that pointed out in our last chapter, 

 is productive of excellent results. And their direct application in 

 the same raw state to lands of which the soils contain an abundance 

 of sulphuric, humic, carbonic, or acetic acid, is also very successful. 



In each case, however, an impalpable state of powder and extreme 

 state of division in the soil are absolutely indispensable. 



Although the principal sources from whence phosphates can be 

 most economically obtained in this country are those just dealt with, 

 it will be interesting for the sake of comparison, to introduce a table 

 of analyses of the different qualities and forms produced and used 

 throughout the world. (See page G6.) 



It will have been noticed that in all cases the chemical value of 

 these bodies is determined by their percentage of phosphoric acid, 

 and it is therefore advisable to here set forth an approximate trans- 

 lation of the scientific formula by which the composition of a phos- 

 phatic body is ascertained. 



The substance destined for examination is first treated with 

 boiling nitric or muriatic acids, which dissolve all its active ingredi- 

 ents, the parts remaining uudissolved being composed principally 

 of sandy and siliceous matter. 



The phosphoric acid, lime, iron, alumina, etc., etc., are all con- 

 tained in the acid solution and are withdrawn from it and estimated, 

 by adding to it other substances for which they have strong affinities, 

 and with which they form insoluble salts. For example, if we add 

 oxalic acid and oxalate of ammonia, they will immediately combine 

 with the lime, to form oxalate of lime, and in that state will fall to 

 the bottom of the vessel. 



