248 THE SYSTEM OF FARM-YAKD MANURING. 



found in the earth in inexhaustible quantities. They 

 generally base their opinion upon some unmeaning che- 

 mical analysis, and demonstrate to the simple agriculturist 

 (for whom alone such disquisitions are intended) how 

 rich his fields still are in some one or other of the mine- 

 ral constituents, and for how many hundred thousand 

 crops the store will still suffice ; as if it could be of the 

 least use for any one to know what the soil contains, if 

 the amount of the available food elements that serve to 

 produce the crops, which is the really important point, 

 cannot be determined. 



With such absurd assertions they absolutely hoodwink 

 our ' practical ' farmers, who, but for them, might see 

 clearly into matters, but who appear only too wilhng to 

 accept any assertion that will only leave them at peace, 

 and save them the trouble of ' thmking.' 



I remember a case where a swindler offered to sell to 

 a wealthy gentleman, at a high price, a mine of almost 

 pure oxide of aluminiimi, after having shown him, from 

 chemical works, that oxide of aluminium was indispen- 

 sable for the production of the metal aluminium, the 

 market price of which was as much as 4:1. per pound, 

 and that the ore of the mine offered for sale con- 

 tained nearly 80 per cent, of that valuable metal. The 

 purchaser was not aware that the ore in question is gene- 

 rally known as ' pipe-clay,' an article of almost nominal 

 value, and that the high price of the metal arises from 

 the many changes through which the oxide has to pass 

 to effect its reduction to the metallic state. 



It is generally the same with the great stores of potash 

 in the soil. The alkaU in the ground, to answer the 

 intended purpose, must, by the agriculturist's art, be con- 

 verted first into a certain form, in which, alone, it is 

 available as food for plants ; and if he does not under- 



