p 



v 



1870.] BROOME — ON CANADIAN PHOSPHATES. 257 



obedience to changes in the physical conditions under which 

 thej may be brought together. 



Finally, in concluding this branch of our enquiries, it may 

 be stated that, reasoning from the researches of Thdnard, 

 Eichhorn, Way, and others, Johnson was led to conclude that 

 the efficiency of mineral manures is, in most cases, to be 

 abscribed to their indirect action, and not, as had been 

 previously supposed, to their direct influence as sources of 

 food to the growing plant. 



We may now pass on to consider the manufacture of 

 " superphosphates" from the mineral apatite, which is at 

 present in progress at but one factory in the Dominion of 

 Canada, namely, at the Brockville Chemical Works, under the 

 management of Mr. A. Cowan, to whose kindness I am 

 indebted for the sample of " superphosphate," the analysis of 

 which will be found below, as well as for valuable information 

 with regard to the process employed. An engine of about 

 fifteen-horse power suffices for grinding the mineral, for 

 turning the agitator during the digestion of the apatite with 

 crude oil of vitriol, and for supplying steam to the sulphuric- 

 acid chambers, which are adjacent to the mills. The quantity 

 of superphosphate of lime obtained does not, at present, exceed 

 six tons per diem, owing to the insufficient yield of the acid 

 chambers. The quality of the product will be seen from the fol- 

 lowing complete analysis recently made upon a fresh sample : 



TABLE V. 

 Analysis of '^ Supekphosphate," op Lime, 



(From Brockville Chemical Worls, Nov., 1S70.) 



Per cent. 

 Superphosphate of Liice 20 . 33 



= CaO, 2nO,.P05. 

 Tribasic Phosphate of Lime 2 . 39 



= 3 CaO, PO5. 

 Phof^phate of Iron (Fea O3) 2.23 



Aluiuiua . 43 



Maguesia tr. 



Dihydrated Salpbate of Lime (J3 . 84 



Gypsum=Ga 0, S O3 -f 2 II 0. 

 Insoluble in Hydrochloric Acid, (piincipally 



Mica) 3 .59 



Chloride of Sodiiun . 45 



"^ater 5 . 50 



Alkaline Sulphates and loss 1 . 24 



Total 100 . 0.) 



R ■ 



