APPLtCATIOX OF EQUILIBRIUM LAW TO SEPARATION OF CRYSTALS. 271 



in presence of KCl and K^SOj is plotted 42 units along the KoClj 

 axis (to the right) and 1-5 unit along the KoSO, axis (downwards). 



Turning to the point M (1000H,O + 25K,Cl,+ llMgSO, + 21MgCL), 

 and similar points representing solutions saturated in presence of three 

 equilibrators, and bearing in mind the fact that the composition of the 



Fig. 3. 



Mg SO4 Axis 



solution cannot be expressed in terms of less than three salts, it is obvious 

 that a correct geometric representation can only be obtained by the use of 

 three co-ordinates. The method chosen has been to plot the reciprocal salt 

 pairs on axes at right angles in a plane, and the total number of molecules 

 in solution on a third axis vertically upAvards from this plane. The sur- 

 faces passing through points in space thus obtained represent areas within 



