46 TRUCK-FARMING AT THE SOUTH. 



terial as dug from the mines and ground. The prepared 

 kainit, No. 3, is made by roasting the crude kainit. 

 The ' dung salt' No. 2, is a waste product, formed 

 in the manufacture of the high grade articles. Nos. 5, 

 6, 7, and 8, are high grade articles of two kinds, viz., 

 the chlorides or 'muriates.' In No. 5, the potas- 

 sium is combined with chlorine, as chloride of potas- 

 sium, or ' muriate of potash,' and in the sulphates, 

 Nos. 6, 7, 8, it is combined with sulphuric acid, as 

 sulphate of potash. Little of No. 8 is manufactured. 



' ' It is becoming customary to characterize these salts by 

 the percentages of sulphate or chloride of potassium they 

 furnish. Thus an ' eighty per cent, sulphate ' is one 

 that contains eighty Ibs. of sulphate of potash in one 

 hundred Ibs. of the salt. An ( eighty per cent, muriate ' 

 would contain eighty per cent, of chloride of potassium. 



MOST DESIRABLE GRADES FOR OUR USE. 



" It is clear that for this side of the Atlantic, the high 

 grades must be the most economical as potash fertilizers. 

 The sulphates are, on the whole, preferable; but the po- 

 tassium in these is more costly than in the chlorides. 

 The chlorides sometimes injure the burning quality of 

 the tobacco leaf, decrease the amount of sugar in sugar 

 beets, and of starch in potatoes, and make the latter less 

 ' mealy ' than is desirable. The sulphates, on the other 

 hand, are always safe. For buckwheat, corn, wheat, 

 oats, and other grains, for leguminous crops and grasses, 

 and for wet soils, the chlorides are preferable because 

 cheaper. Generally speaking, the most desirable grades 

 will probably be : 



" For sulphates: the highest grades which contain from 

 seventy-five to ninety per cent, or more, of sulphate of 

 potash, corresponding to from forty to fifty per cent, of 

 actual potash. 



