228 ON A DIAGRAM OF FREEZING-POINT 



If the 1 2 (1.80) intersection, were assumed as the starting 

 point of the curve, the mean curve would cut the 2 4 (1.86) 

 line. If, therefore, association in molecules with unchanged 

 mode of ionization were assumed, some formation of triple mol- 

 ecules would be indicated, and if the associated molecules were 

 assumed to dissociate into two free ions, a greater extent of such 

 association would bo indicated. Thus, with this starting point, 

 less probable assumptions as to association must be made, to 

 account for the observations. 



If the 1 2 (1.84) or even the 1 2 (1.845) intersection were 

 taken as the starting point, the curve must bend considerably to 

 the left before running out, of which bending none of the 

 experimental curves give any indication whatever. 



The most probable conclusion, then, that we can draw from 

 the observations, is that the depression constant is 1.85, with a 

 limit of error of .01, or perhaps .005, that the electrolyte has 

 single molecules at great dilution, and that as dilution diminishes, 

 either double molecules with unchanged mode of ionization form 

 to a considerable extent, or double molecules dissociating into 

 two ions, to a small extent. 



Loomis's and Barnes' observations, on which the NaCl 

 (L B B) curve is based, are also in close agreement; but as 

 Loomis's curve for slightly greater dilution bends slightly to the 

 right, the upper part of the L B B curve should probably 

 have greater curvature. Jones' curve for moderately dilute 

 solutions runs a little to the left of it, and at higher dilutions 

 diverges markedly to the right, as separately shown. Abegg's 

 observations are on both sides of it, but at higher dilutions his 

 curve also goes to the right. Raoult's touches it, but goes off to 

 the right. Arrhenius's is considerably to the right, and goes 

 widely rightward at greater dilutions. Ponsot's is a little to the 

 left. As the L B B curve is plotted with Barnes' coefficients, 

 it is probably too low. If it be raised about as much as was 

 found necessary in the case of the KClcurve.it will lie along the 

 1 2 line, or a little above or below it, with its upper end, as 

 drawn, so directed, as to run out probably at a point nearer the 



