BANCROFT. — TERNARY MIXTURES. 341 



as solvents, In Tables IX.-XIII. I give the measurements made 

 with ether and water, ethylacetate and water with the consolute liquids 

 alcohol, methylalcohol, and acetone. In Tables IX. and XI. the ex- 

 periments were made with saturated solutions ; in Tables X., XII., and 

 XIII., with pure liquids. The first method has the advantage that the 

 readings obtained are final, involving no correction and no knowledge 

 of the mutual solubilities. On the other hand, it is necessary to keep 

 the solutions in the burettes at the same temperature as that at which 

 one makes the determinations, a very difficult thing to do usually, so that 

 the second method is to be preferred. The exponential factors are the 

 same according to both methods, as I have already shown. The inte- 

 gration constants are diff'erent, standing to each other in the relation 

 given in Equation (18). It would have been well if I had determined 

 the densities of the saturated solutions so that they could be recalculated 

 into cubic centimeters of the pure liquids ; but I shall have to make 

 an extended series of density determinations in connection with the 

 equilibrium between two liquid phases, and I have postponed these 

 others till then. The measurements in Tables IX.-XIII. are about as 

 accurate as those in Tables I.-VI., with the exception of the solutions 

 when water is part solvent. The precipitate in these cases is lighter 

 than the solution, consists of a few drops only, and is very difficult to 

 distinguish from air bubbles, especially in the ether solutions, where the 

 clouding at best is very slight. For this reason the first series in each 

 table must be considered as very doubtful as the absolute measure- 

 ments go. The determination of the saturation point for these cases 

 depended on the light, the state of my eyes, and the mood which I 

 happened to be in on the days when the measurements were .made. 

 So difficult are the determinations sometimes, that I give no results for 

 ether-water-acetone because I obtained different measurements every 

 day. The agreement between the observed and the theoretical values 

 is no test of the absolute accuracy of either ; but merely shows that the 

 solutions follow the same general law, the constants, exponential, and 

 integration varying with the degree of cloudiness which the observer 

 takes as denoting the point of saturation. The values of n are not so 

 accurate as in the first set of tables, because the curves cover a more 

 limited extent, and therefore the variations are smaller, and because 

 when the value of n is large, say over 2, a very slight change in the 

 direction of the logarithmic curve produces a very large corresponding 

 change in n. The amounts of ethylacetate and water which dissolve 

 in 5 c.c. of alcohol, methylalcohol, or acetone were so large that I was 

 forced to work with one cubic centimeter of these liquids as solvent. 



