232 ON A DIAGRAM OF FREEZING-POINT 



markedly to the right, although it is farther to the left at its 

 lower end. Arrhenius's is considerably to the right, and diverges 

 widely rightwards. The Na 2 SO 4 (L A A) curve is also almost 

 coincident with both the Loomis and the Archibald curves. Both 

 Raoult's and Arrhenius's are considerably to the right, and 

 diverge slowly rightwards. Such of these curves as are entered 

 on the diagram, being plotted with Archibald's coefficients, are 

 probably somewhat too high or too low, as the case may be. 

 Those for great dilutions are too discordant to admit of dis- 

 cussion. The mean curves for both salts have the fame general 

 form, and run down, as drawn, a little below the 2 3 line. 

 Their upper ends are so directed as to suggest their running out 

 at the 2 3 (1.85) intersection, or thereabout. At their lower 

 ends they turn sharply to the left and cross the 2 3 line, going 

 towards the region of the double molecule curves, or of the 2 2 

 curve. The turns are too sharp, and the 4 6 and 6 9 lines 

 too near, to make their transformation into double or triple mol- 

 ecule curves, with unchanged ionization, probable. The diagram 

 suggests rather their transformation into 4 5, 4, or 2 or 2 2 

 c urves. If this be accepted, it means that at extreme dilution 

 these sulphates exist in solution in single molecules, dissociating 

 into three ions, that partial dissociation into two ions or doubling 

 of molecules sets in, apparently at an early staije, but increases 

 more slowly than in the case of H 2 SO 4 , until the dilution has 

 been considerably diminished, when it undergoes a rapid increase. 

 A close determination of the depression constant cannot be made; 

 but even if the curves have to be either raised or lowered a little, 

 and if, Loomis's tendency being leftward, their upper parts have 

 to be shifted somewhat to the right, they will be consistent with 

 its being about 1.85. 



The Na 2 CO 8 curves are too discordant to form a basis 

 for discussion. But either Loomis's curve or a mean 

 curve, or even Jones's curve itself, is quite consistent 

 with a depression constant of about 1.85 ; and both curves indi- 

 cate the occurrence of rapid association or of rapid change of ioni- 

 zation after considerable diminution of dilution. The fact that 



