DIVISION OF CHEMISTRY 253 



SESSIONAL PAPER No. 16 



It is evident from these results that this residue is very rich in potash and one 

 that should prove of considerable agricultural value. 



The question naturally arises : Would the associated manganese dioxide have any 

 injurious effect on vegetation? Experiments have shown that small quantities of 

 soluble manganese compounds act as stimulants on plant growth, but that larger 

 amounts are toxic. The manganese in this residue is quite insoluble, and there seems 

 no reason to suppose that any injurious effect would follow its application. As yet 

 we have no results from practical field tests with this material and, therefore, it can- 

 not be definitely stated that the manganese would not become, in the course of time, 

 more or less soluble in the soil. If such proved to be the case and injury to crops 

 resulted the potash salts could be leached from the residue and subsequently used in 

 fertilizer preparations. But any such injury to crops is not to be feared and we 

 should have no hesitation in using it, in the ordinary application that potash fertil- 

 izers are made. 



ROCK SUPPOSED TO CONTAIN POTASH. 



Laboratory No. 11683. — The active search that has been prosecuted in the United 

 States during recent years for native sources of potash has, in some degree, spread 

 to Canada. This has led to sending to the Farm laboratories by explorers and others 

 of several samples of rocks, mineral waters and brines supposed to contain potash 

 in notable quantities and in a condition more or less available for agricultural pur- 

 poses. So far the quest has not been sucessful and, to the best of our knowledge, the 

 sea-weeds of our coasts remain to-day the only native source of potash suitable, 

 without treatment, for agricultural purposes. The analytical data now to be given 

 are from a rock specimen obtained in the East Kootenay, B.C. It was soft and of 

 a slaty-grey colour, with irregular veins or pockets of a lighter and softer material 

 scattered throughout it. For analysis the whole sample was crushed to a fine powder. 



For water-soluble potash five grams were shaken for five days in 1000 cc. of dis- 

 tilled water and filtered. The filtrate contained -0927 per cent potash. Qualitative 

 analysis showed the presence of a considerable amount of sulphate of lime. 



Digestion with hydrochloric acid. This involved digestion with strong hydro- 

 chloric acid (Sp. Gr. 1-115) for several days at the temperature of boiling water. 

 The results obtained are as follows. 



Analysis. 



Per cent. 



Insoluble rock matter 8-72 



Oxide of iron and alumina (Fe 2 3 , Alo0 3 ) 106 



Lime (CaO) 29-10 



Magnesia (MgO) 6-38 



Soluble silica (SiO,) -43 



Sulphuric acid, combined (S0 3 ) 26-98 



Phosphoric acid (P 2 5 ) trace 



Potash -25 



Water, carbonic acid, etc., by difference 27-58 



100-00 



Total potash by fusion. For this determination, the rock was thoroughly decom- 

 posed by fusion with alkaline carbonates, and the result lixiviated with dilute acid. 

 The solution contained -51 per cent potash. 



It is evident, in the first place, that the rock is essentially sulphate and carbonate 

 of lime and might be regarded as a low-grade gypsum. 



Secondly, these three analyses are conclusive in showing that this rock has no 

 value as a commercial source of potash. 



