138 POTASH MANURES 



Examination of Potash Salts. 



127. Qualitative Examination. 



Kainit, sulphate of potash, and muriate of potash 

 are tested qualitatively for calcium, magnesium, sodium, 

 sulphate, and chloride. The amount of insoluble 

 material is to be noted, and an attempt made to gauge 

 roughly the relative quantities of magnesium, sulphate, 

 and chloride. In the case of the sulphate and muriate 

 of potash, this may give some indication of purity 

 without having recourse to analysis. 



Analysis of Potash Salts. 



Generally speaking, it is sufficient to estimate the 

 potash only, since the manures are bought and sold on 

 this basis. If there is any evidence of sophistication, 

 however, it may be necessary also to estimate the 

 sulphate and chloride present. 



128. Potash. 



id) In Muriate of Potash free from Sulphates, — A 

 weighed portion of the sample (about 5 grams in the 

 case of concentrated muriate of potash, or lo grams in 

 the case of low-grade muriate) is dissolved in water, 

 the solution filtered if necessary, and made up to 

 500 C.C. in a measuring flask. Fifty c.c. of the solution 

 are pipetted into a porcelain basin, a few drops of 

 hydrochloric acid added, and also 10 c.c. of a 10 per 

 cent, solution of platinic chloride. After evaporation 

 to a syrup on the water-bath, the contents of the basin 

 are allowed to cool, the residue is digested with 80 per 

 cent alcohol (sp. gr. = 0-864) and then transferred to 

 a tared filter paper, or weighed Gooch crucible, 

 where washing with diluted alcohol is continued until 



