216 PROCEEDINGS OF THE CHEMICAL DEPARTMENT. 



muriate of potash alone and intermixed with other substances on 

 the turnip, and, as already mentioned, to compare these sub- 

 stances with Peruvian and Bolivian guanos, as usually employed. 



The system adopted was similar to that used in 1866. The 

 manures were employed in such quantity as to give to the acre 

 of land 112 lbs. of soluble phosphoric acid, 56 lbs. of ammonia, 

 and 56 lbs. of potash. In certain of the trials, however, where 

 ammonia and potash were used together, it was considered that 

 56 lbs. of each was a quantity so large that it would never be 

 applied in practice, and in these cases 28 lbs. of ammonia and 

 28 lbs. of potash were used. The mode in which the quantity 

 of the particular manures to be used was ascertained is very- 

 simple. Take, for example, the case of the dissolved coprolites ; 

 the percentage of soluble phosphoric acid was first determined 

 by analysis, and then by calculation it was ascertained how much 

 of the manure must be used to supply this quantity, and that 

 formed the application for the acre. 



The manures employed were — 



1st, Dissolved phosphatic guano, of which the composition was 

 found to be — 



Water, 18-41 



Organic matter, 12 '99 



Biphosphate of Lime, equal to 3173 Soluble Phosphates, 20 - 34 



Insoluble Phosphates, 12"35 



Sulphate of Lime, 31 - 04 



Alkaline Salts, ........ T13 



Sand, 374 



100-00 

 Ammonia, 071 



It was intended that in this manure the whole of the phos- 

 phates should have been rendered soluble, and it was made with 

 this object, but, unfortunately, when finished it was found that 

 a considerable quantity was insoluble, and as it so happened 

 that no other manure which suited the purpose was to be found 

 in the market at the time, we were under the necessity of 

 using it. 



2d, Dissolved coprolites. — This sample was found on analysis 

 to contain — 



Water, 16-06 



Organic matter, 7 - 69 



Biphosphate of Lime, equal to 24 - 65 Soluble Phosphates, 15*80 



Insoluble Phosphates, 10-51 



Sulphate of Lime, 45 "42 



Alkaline Salts, 0"24 



Sand, 4-28 



100-00 

 Ammonia, - 19 



