26 MODERN HIGH FARMING. 



ready described would form sulphuric acid, which, combining with 

 the oxides in the soil to form sulphate of iron, would immediately 

 render cultivation or vegetable growth impossible. 



The counteracting or preventive part here played by lime is at 

 once manifest, since by its ready absorption of the acid it would in- 

 terfere with any other combination and become, itself, more soluble 

 and efficacious by its transformation into gypsum. 



Apart from such special cases as these, the virtues of lime must be 

 attributed to its caustic action upon all organic remains. 



Being rich in unavailable because insoluble forms of nitrogen, these 

 are rapidly decomposed, and by coming in contact with other agents 

 are submitted to the nitrification process and rendered assimilable? 

 and this has given rise to the assertion that to spread lime upon a 

 newly plowed cultivated field is equal to the application of a good 

 dose of soluble nitrogenous fertilizer. 



As we shall presently show, its intimate admixture in a finely 

 powdered state with all kinds of clayey soils is invaluably diminish- 

 ing as it does their plasticity and augmenting their permeability to 

 the action of air and water. 



We have explained that phosphoric acid invariably exists in the 

 soil in combination with peroxide of iron or alumina ; these two 

 agents must therefore exercise an immediate transforming action 

 upon the phosphate of lime which is introduced in both natural and 

 artificial manures. 



This transformation can be demonstrated by adding either per- 

 oxide of iron or alumina, or both, to a solution of phosphates in 

 water charged with carbonic acid gas (ordinary seltzer water at 

 high pressure), when in a very short time all the phosphoric acid 

 will have disappeared from the solution, and be found in the deposit 

 as phosphate of peroxide of iron. 



Now, if one gramme of this ferric phosphate be put into water 

 with two or three grammes of carbonate of lime, and be allowed, 

 with frequent shakings, to stand for forty eight hours the mixture 

 at the end of that time being poured into an excess of seltzer water 



