COBALT CHLORIDE AND ALUMINIUM CHLORIDE. 



211 



the very greatest precautions are taken. Moreover, two solutions of nearly 

 equal concentrations differ so little in color, as to make the error which 

 necessarily arises in estimating that the colors have been made the same by 



0.07 



0.06 



0.05 



0.03 



0.01 



CoCI 2 + AIC! 3 



0.5 



1.0 1.5 



Concentration 

 FIG. 74. 



z.o 



2.5 



the act of diluting, relatively great. (I) When the concentrations of two 

 solutions differ by a reasonable amount, it is not possible to dilute the bluer 

 solution until it assumes the same color as the less blue solution, because the 



