PROCEEDINGS OF THE CHEMICAL DEPARTMENT. 395 



its rapidity may, in some cases at least, depend to no small 

 extent on the nature of the soil, but it is only by field experiment 

 that any satisfactory conclusions can be arrived at. 



Tn order to submit these points to experiment, there were 

 used three different kinds of superphosphate, made respectively 

 from guano, bone-ash, and coprolites, without any admixture. 



For the first, a manure made from Baker's Island Guano was 

 selected, because that substance is the type of a guano phosphate, 

 and contains so small a quantity of ammonia that it may bu 

 practically neglected. The sample used contained — 



Water, 25*05 



Organic Matter, : 12-10 



Biphosphate of Lime, equal to 38*65 soluble phosphates, 24*77 



Insoluble Phosphates, 



Sulphate of Lime, 37*90 



Alkaline Salts, trace. 



Sand, 0*18 



100*00 

 Ammonia, 013 



This manure, though rather too moist, was very uniform, and, 

 from the fact that all the phosphates had been rendered soluble, 

 was particularly well fitted for the experiments. 

 The dissolved coprolites contained — 



Water, 22*60 



Organic Matter, &c, 9*77 



Biphosphate of lime, equal to 23*07 ) ,.,„„ 



soluble phosphates j 



Insoluble phosphates, 5*08 



Sulphate of lime, 42*82 



Alkaline salts, 0*28 



Sand, 4*65 



100*00 



Ammonia, None. 



Here, as usually happens with coprolites, a certain quantity of 

 the phosphates remained undissolved, and this may be considered 

 as unavoidable, in consequence of the compactness and difficult 

 solubility of the original substance. 



The Dissolved Bone-ash contained — 



Water, 19*15 



Organic matter, &c, 7*42 « 



Biphosphate of lime, equal to 30*30 ) 10-49 



soluble phosphates, ) 



Insoluble phosphates, 11*70 



Sulphate of lime, 38*06 



Alkaline salts, 0*30 



Sand, 3*95 



100*00 

 Ammonia, None. 



