POTASSIUM FERTILIZERS 169 



The potassium sulphate is separated from the liquor by 

 centrifugal force, at a temperature of 40 C. (104 F.). 

 Potassium sulphate made from schoenite is largely used 

 for agricultural purposes. 



Potassium Sulphate from Potassium Chloride and 

 Sulphuric Acid. This process is similar to the I^eblanc soda 

 process, p. 66, coarsegrained potassium chloride being 

 employed. Sulphuric acid of a specific gravity of 1*67 is 

 used for the reaction, and should, for purposes of economy, 

 be made on the spot. It is unnecessary to use as strong an 

 acid as in the lyeblanc process, because the temperature of the 

 action of potassium chloride is higher than that of sodium 

 chloride. Sulphate of potash manufacturers prefer an open 

 build of furnace, i.e. reverberatory, since a high temperature 

 is required for decomposition. The ordinary decomposing 

 pans are worn out in half the time they would serve for the 

 L,eblanc processes. The hydrochloric acid produced is 

 saved, as in the lyeblanc process. From a high grade potas- 

 sium chloride of 98 % purity a potassium sulphate of 95 % 

 purity can be made. 



Potash Manure Salts. There are many by-products 

 in those industries where crude potash salts are produced. 

 Fertilizers have been placed upon the market under the 

 simple name of " Potash Manure Salts," blended up to some 

 even figure of potash content, 20, 30 or 40 % ; these manures 

 increased in popularity during the early years of the twentieth 

 century. The constituents which enter chiefly into potash 

 manure salts are natural sylvinite, kainite, muriate of potash 

 or artificial carnallite and schoenite. On account of the 

 different materials from which these potash manure salts 

 are prepared, there is great variation in their colour and general 

 appearance ; inspection is little guide to value. A typical 

 sample of a 30 % potash salt contains about 48 % of potassium 

 chloride, 27 % of sodium chloride. Sulphate of potash is the 

 most difficult to produce, and, in consequence, the unit price 

 of the potash in sulphate of potash is the highest ; whilst the 

 miscellaneous potash manure salts are usually the cheapest 

 per unit. 



