720 



BOAED OF AGRICULTURE. 



Ground Itock Phosphate. 



[Sent on from West Springfield, Mass.] 



Per cent. 



Moisture at 100° C, 0.10 



Total phosiihoi-ic acid, 80.51 



Soluble phosiilioric acid, None. 



Revei'ted ijhosphoric acid, 0.19 



Insoluble phosphovic acid (2 cents per pound), . . . 30.31 



Magnesium oxide, 3.03 



Calcium oxide, 41.87 



Ferric and aluminum oxides, 4.26 



Lisoluble siliceous matter, 13.74 



The material is of but little value for manurial pui-poses, 

 without a previous treatment with sulphuric acid, to render 

 its phosphoric acid available. 



South Carolina Roch Phosphate. 



[Sent on from Ashby, Mass.] 



Moistin-e at 100° C, . 

 Total pliosphoric acid. 

 Soluble iihosphoric acid. 

 Reverted iihosphoric acid. 

 Insoluble phosphoric acid, 

 Insoluble matter, . 



Per cent. 



1.68 



25.81 



0.27 



0.47 



25.07 



11.64 



The material is of fair composition, and ought to be manu- 

 factured into su]ierphosphate before used. 



Natural Phosphate. 



[Sent on from New York.] 



The article is characterized by the presence of a liberd 

 amount of sesquioxide of iron and alumina. Actual field ex- 

 periments have to decide its agricultural value. 



