300 



CHEMICAL MANUEES. 



deposit. Kaiiiit, as it is extracted in considerable quantities from the 

 Leopoldshall, New Stassfurt and Kalusz mines, is freed as much as 

 possible from common salt intercalated with it, then it is reduced to 

 fine granules in a salt mill. It is put on the market as ground 

 kainit, and contains on an average 65 to 75 per cent of pure kainit 

 or 23 per cent of sulphate of potash (equal to 12-4: per cent of 

 potassium).^ The impurities consist chiefly of common salt and 

 clay. Formerly, kainit was calcined and ground. This process 

 has been abandoned in the Stassfurt factories. As it readily cakes 

 and is then very difficult to break up, it has been mixed, on the 

 advice of Fleischer, with 2*5 per cent of peat powder, which prevents 

 this drawback. The same means is used for other potash salts 

 when they are sold for manure. - 



4. Schoenite is the double sulphate of potassium and magnesium 

 and responds to the formula K.,SO^ + MgSO^ + 6H.,0. Its forma- 

 tion at the expense of the kainit by elimination of the chloride of 

 magnesium would therefore be very plausible ; its existence as a 

 mineral is not established with certainty. Artificial schoenite will 

 be described further on. 



5. Polyhalite. — It is found in veins of 26 to 33 metres thick in 

 the deposits of rock salt. It is mostly amorphous, rarely crystalline, 

 of a grey colour and conchoidal fracture. Density 2*72. 



TABLE XCIX.— ANALYSIS OF POLYHALITE. 



Per cent. 

 Potassium sulphate ....... 27-90 



Magnesium ,, 

 Calcium ,, 



Water .... 



Common salt and impurities 



19-76 



42-64 



5-75 



3-49 



99-54 



1 Should be, potassium equal to 12-4 per cent of potassium oxide K^O. — Tr. 



2 The breaking up of kainit is a costly job. It should not be stored in bags 

 piled one on the top of the other, but on arrival it should be shot in a dry place, 

 covered in of course, and with a smooth dry floor. It can be brought from there 

 readily in a barrow to where it is wanted . by one man, whereas it takes two men 

 to lug and tug about the caked bags and cut them open with a knife to get 

 out the kainit solid as a rock, and then the tiresome job begins of pounding it 

 with wooden mallets to break it up, and the small amount a couple of men can 

 break up and screen in a day is well known to those who have been kept waiting 

 for it to complete the ingredients in a heap that is to be dry mixed. A little 

 better progress is made with the disintegrator, but even then it is a heart-rending 

 job, as no sooner is the disintegrator started and well under weigh after a 

 stoppage than the naturally moist kainit again blocks it. The advice of the 

 translator is therefore to shoot the bags at the outset. The pressure cannot find 

 vent without bursting the bags, therefore the kainit must consolidate and perforce 

 eake into a soUd as hard as in the original rock. 'The store should be an oblong 

 "building with the door in one end, and the concrete floor should rise gradually to 

 fthe far end, where kainit and other water-soluble products should be stored be- 

 jond the reach of floods. — Tr. 



