49^ AGRICULTURAL ANALYSIS 



Equivalent to 



Per cent. 



Potassium chlorid 26.8 



Magnesium chlorid 34.2 



Water 39.0 



The commercial article as taken from the mines, as is seen 

 above, has less potash (K 2 O) than kainit, the mean content being 

 about nine per cent. Those proposing to use this body for fer- 

 tilizing purposes should bear in mind that it contains less potash 

 and more chlorin than kainit. 



Carnallit occurs in characteristic brown-red masses. On ac- 

 count of its highly hygroscopic nature it should be kept as much 

 as possible out of contact with moist air and should not be ground 

 until immediately before using. 



By reason of the greater bulk in proportion to its content of 

 potash and its hygroscopic nature and consequent increased dif- 

 ficulty in handling, the cost per unit of potash in carnallit is 

 greater than in kainit. 



In some localities small quantities of ammonium chlorid have 

 been found with carnallit, but not to exceed one-tenth per cent. 

 It has, therefore, no practical significance to the farmer, but may 

 be of interest to the analyst. 



424. Polyhalit. Polyhalit is a mineral occurring in the Stass- 

 furt deposits consisting of a mixture of potassium, magnesium, 

 and calcium sulfates, with a small proportion of crystal water. 

 This mineral, on account of its being practically free of chlorin, 

 is one especially desirable for use in those cases, as in the culture 

 of tobacco, where chlorids are injurious. Unfortunately, it does 

 not occur in sufficient quantities to warrant the expectation of 

 its ever being found in masses large enough to become a gen- 

 eral article of commerce. It is found only in pockets or seams 

 among the other Stassfurt deposits, and there is no assurance 

 given on finding one of these deposits of polyhalit that it will 

 extend to any great distance. The composition of the mineral 

 is shown by the following formula: K 2 SO 4 .MgSO 4 .(CaSO 4 ) 2 . 

 H 2 O. Its percentage composition is shown by the following num- 

 bers: 



