247-250] Analysis of Manure Cakes 



149 



ANALYSIS OF POTASSIC MANURES: KAINIT, 

 MURIATE OF POTASH, SULPHATE OF POT- 

 ASH, &c. 



247. As a rule, nothing but the potash is estimated in these 

 substances. Occasionally, however, a somewhat fuller analysis 

 is required. 



248. Moisture is estimated as usual. 



249. Sand is estimated by dissolving in water slightly acidu- 

 lated with HC1, filtering, washing, and igniting and weighing. 



The other two substances are potash and magnesia. 



250. Potash. — The simplest method is as follows : Weigh 

 out *5 gram, dissolve in water with a small amount of dilute 

 HC1, filter off the sand and wash well. To the filtrate add 

 about -5 gram pure NaCl and 15 c.c. PtCl 4 solution (10 grams 

 PtCl 4 in 100 c.c. H 2 0). Evaporate exactly as described in para- 

 graph 33 to a pasty state. Add 2 c.c. PtCl 4 solution. Shake 

 round the beaker, allow to stand for five minutes, and filter 

 through two counterpoised papers. Allow the whole of the 

 liquid to run through, then with the least possible quantity of 

 PtCl 4 solution (not more than 3 c.c.) rinse the beaker and wash 

 the precipitate. When the liquid has again entirely passed 

 through, the rest of the precipitate must be removed to the 



