Sulfate of Potash- Magnesia 27 



bottom of the beaker and a scum on the 

 surface of the Kquid, add 10 or 20 cc. more 

 of water and heat, repeating the addition of 

 small amounts of water and heating, if 

 necessary, until the magnesium sulfate is 

 all dissolvd. Filter, using the Witt plate, 

 and concentrate the clear filtrate until the 

 liquid is saturated as indicated by the for- 

 mation of a scum on the surface. Mix 

 the two hot saturated salt solutions and set 

 the mixture aside for at least twelve hours. 

 Both the solutions must be saturated upon 

 mixing or the experiment will be a failure. 

 The crystals that begin to form upon put- 

 ting the solutions together and which further 

 separate on cooling are the double sulfates of 

 potassium and magnesium, K2SO4 • MgS04- 

 6H2O, sometimes cald the sulfate of potash- 

 magnesia. 



After the mixture has stood, filter off the 

 crystals, drain them well on a Witt plate, 

 transfer them to a paper and weigh. Save 

 the filtrate which contains a solution of arti- 

 ficial carnallit. 



The crystals of double sulfate may be dried 

 in a few hours by spreading on paper when 

 the exact weight may be obtaind or the 

 approximate weight may be had at once, 

 assuming that 5 to 6 per cent of the weight is 

 water adhering to the crystals. 



