36 Preparation of Substances 



' Each of the crystals has its definit shape which is 

 easily seen under the microscope. Reference is given 

 to various figures of crystals in Watt's Dictionary of 

 Chemistry, Vol. II, pages 148 ff. 



The hydrated double sulfate of potassium and mag- 

 nesium is inclined to form coarse monoclinic prisms 

 which lo.k hke half cubes or diamonds which have 

 been prest so that the upper faces are not directly over 

 the lower ones. Compare Figs. 285 and 287. 



Potassium chlorid, hke sodium chlorid, appears in 

 cubes or colums, or commonly as a four-sided funnel 

 or hollow pjTamid. 



Potassimn sulfate may be in small hexagonal prisms 

 (really rhombic) or in longer prisms with a bluntly 

 tapering end. Vid. Figs. 272 and 297. Similar figures 

 are shown in Gmelin-Kraut, Vol. 2i, p. 49. 



Magnesium sulfate is inclined to grow in long 

 needles (rhombic) with faces on the very abrupt end. 

 Vid. Fig. 281. 



Magnesium chlorid, MgCl2 • 6H2O, forms mono- 

 clinic prisms much like the double sulfate of potash- 

 magnesia. Vid. Figs. 285 and 287. 



QUESTIONS 

 (To be answerd in notebook.)] 



1. Calculate the per cent of potash, K2O, in the 

 sulfate of potash-magnesia; in potassium sulfate; in 

 potassium chlorid. Express results as follows: 



K2O 94.3 ^ ^^^^^^^ 



K2SO4 174.4 



2. Tell when a solution is saturated. 



3. How many pounds of potassium chlorid in a ton 

 of muriate of 80 per cent grade? 



