acid water does not withdraw from the soil the phosphate of 

 lime contained in it, but wherever it meets with the granules 

 of apatite, or phosphorite, it dissolves a certain portion. 

 Under these circumstances, a solution of phosphate of lime 

 must, consequently, be formed, which spreads in all directions 

 around each granule. Wherever this solution comes in 

 contact with soil not already saturated with phosphate of 

 lime, the soil will take up and retain a certain portion of 

 this salt. The portion of soil now saturated with phosphate 

 will oppose no further obstacle to the wider diffusion of the 

 solution. 



Voelcker (Bied. Centr. 1880-866, 867) as quoted in the 

 journal of the Chemical Society (Eng.) vol. 24, second series, 

 page 640, draws the following conclusions: 



1. Phosphates are not readily taken up by plants in a 

 soluable form [water soluble], but must be returned to an 

 insolu^sle condition before they yield their useful properties. 



2. The efficacy of insoluble calcium phosphate corresponds 

 with the minuteness of division in which it is found in a 

 fertilizer. 



3. The finer the particles in a phosphatic material, the 

 more energetic its action as a manure. 



Fleischer and Kissling (Bied. Centr. 1883-155, 161) on 

 the application of insoluble phosphates to soils, found that 

 the action of moorland soils when mixed with insoluble 

 phosphates is to render a portion of the phosphate soluble 

 in water, amounting to 55 per cent, in one case, of the total 

 phosphoric acid; a portion at the same time was reduced to 

 the di-calcium salt, and in one compost heap as much as 17 

 per cent, of the total acid was brought into this form. 



The general out-come of the above mentioned experiments 

 is that it is more advantageous to apply insoluble phosphate 

 than superphosphate on humous soils, as they are capable of 

 bringing insoluble phosphate into a soluble condition. This 

 applies, however, only to peaty soils, or those containing de- 



