26 



WORK OF C M. ST1NE. 



The other symbols employed have the usual significance. 



Without further extending this method of calculation, it is evident that it does 

 not give the true value of the hydrates formed, and that the hydrating power is 

 larger for the more concentrated mixtures than would be indicated by the propor- 

 tions given below. 



This is just what we should expect, since with increasing hydration we do not have 

 the process of loss of water from the hydrates formed in separate solution going on 

 to the end in the mixture, but instead we have, necessarily, a condition of equili- 

 brium between the hydrating powers of the two salts. Also, as a direct result, the 

 amount of water thus left uncombined affects the final composition of the hydrates, 

 as already indicated. 



This condition of equilibrium is not represented by the proportions given above, 

 since the amount of water playing the part of solvent is not that indicated by these 

 proportions. 



Table 13. Freezing-point Lowering, Calculated and Found. 



m 



m c 



u 



L' 



Sum. 



0.3 CaCl 2 . 

 0.3 MgCl 2 . 

 0.5CaCl 2 . 

 0.5MgCl 2 . 

 0.7CaCl 2 . 

 0.7 MgCl 2 

 0.9CaCl 2 . 

 0.9 MgCl 2 . 

 1.3CaCl 2 . 

 1.3 MgCl 2 . 

 1.7CaCl 2 . 

 1.7 MgCl 2 . 



0.15 

 0.15 

 0.25 

 0.25 

 0.35 

 0.35 

 0.45 

 0.45 

 0.65 

 0.65 

 0.85 

 0.85 



4.224 

 4.330 

 4.109 

 4.050 

 3.936 

 3.902 

 3.755 

 3.862 

 3.548 

 3.570 

 3.371 

 3.332 



4.682 

 4.748 

 4.685 

 4.715 

 4.547 

 4.808 

 4.438 

 4.897 

 4.394 

 4.639 

 4.251 

 4.487 



5.16 

 5.29 

 5.52 

 5.44 

 5.71 

 5.64 

 5.77 

 5.92 

 5.94 

 5.97 

 6.06 

 5.96 



If we consider that the values of M for calcium chloride and for magnesium 

 chloride in separate solutions, since their hydrating powers are nearly equal, repre- 

 sent the relative hydrating powers under the same conditions for the two salts, 

 at the concentration corresponding to any pair of values of M, then it becomes 

 possible to calculate the approximate composition of the hydrates of calcium chloride 

 and magnesium chloride in the mixture. Selecting, for example, the mixture con- 

 sisting of 1 part of 1.7 N calcium chloride and 1 part of 1.7 N magnesium chloride, 

 then : 



Let X equal the number of grams of water eliminated in the formation of the 

 hydrate of calcium chloride which occurs in the mixture in question. If the hy- 

 drates of calcium chloride and magnesium chloride in the mixture are related as they 

 are in separate solutions, they will be to each other as 18.9: 21.7 (see tables 9 and 10), 



217 

 hence, rrrX = the number of grams of water eliminated in the formation of hydrate 

 lo9 



of magnesium chloride in the mixture. 



