144 AMERICAN MANURES. 



acid through this agency. On the contrary, it is 

 more rich in phosphoric acid than ordinary 

 bones, which fact is accounted for by the removal 

 of the gelatin originally contained in the bones 

 of marine animals of which the mineral phos- 

 phate is made up. Again, we do not find that 

 this mineral phosphate has any noticeable effect 

 upon the vegetation of the soils in which it is 

 found, in such immense quantities as to require 

 removal in order that the land may be cultivated. 

 The above facts are in strict accordance with the 

 results attained by the experiments of celebrated 

 chemists upon mineral phosphates. These ex- 

 periments have demonstrated that pure water 

 has no appreciable effect on them, and that 

 solutions of salts of ammonia and of soda, much 

 stronger than can be found in soils, have but a 

 very slight effect upon them. Hence, as organic 

 and mineral acids exist only .as traces in soils, 

 we may safely assert that they have no ap- 

 preciable effect upon them, but that crude ground 

 mineral phosphates must remain inert and useless 

 in the soil ; their only possible value in the crude 

 insoluble state consists in the carbonate of lime 

 they contain, which can be purchased at one 

 tenth the price paid for in mineral phosphates. 



Soluble Phosphoric Acid is produced by the 

 action of sulphuric acid on bone phosphate of 

 lime, phosphate of magnesia, and phosphates 



