DEPRESSIONS FOR ELECTROLYTES-—-MACGREGOR. 229 
1—2 (1.85) intersection, than either the 1—2 (1.83) or the 1—2 
(1.87) intersection. Thus the defective data as to ionization 
prevent our drawing a more definite conclusion than that the 
association indicated, if any, is less than in the case of KCl, and 
that the depression constant is 1.85, with a limit of error of 
perhaps .02. 
The HCl curve is interesting as exhibiting a point of mini- 
mum equivalent depression. The observations on which the 
L B—B curve is based, are in good agreement. Jones’ curve 
almost coincides with it in the lower part, but goes off to the 
right in the upper part and at higher dilutions, as shown separ- 
ately. Loomis’s curve at higher dilutions (also separately shown) 
goes to the left, but in a less marked manner. As drawn, the 
upper part of the mean curve lies between the 1—2 and 2—4 
(1.85) lines, and it is running out to a point a little beyond the 
1—2 (1.86) intersection (see inset). But as it is plotted with 
Barnes’ co-efficients it is perhaps too low. If raised 1 or 2 per 
cent. it would appear to run out at some point between the 1—2 
(1.84) and 1—2 (1.86) intersections. The data are of course very 
defective ; but they are consistent with a depression constant of 
about 1.85, and they seem to indicate a greater extent of associ- 
ation than in the case of KCl. 
The L—D and J—D curves for NH,Cl are not in agreement, 
having the usual relative position of Loomis’s and Jones’ curves. 
A mean curve based on their lower parts would be slightly to 
the left of the 1—2 (1.85) line, and directed to a point consider- 
ably to the right of the 1—2 (1.86) intersection, It might thus 
indicate anything between a high value of the depression con- 
stant accompanied by very considerable association of molecules, 
and a constant of about 1.85, with no association in dilute 
solutions, and only a slowly increasing association in stronger 
solutions. 
The HNO, curve (see inset) is a mean curve based on 
Loomis’s and Jones’s. Both are beyond the bounds of the inset, 
the former to the left, the latter to the right. Neither this curve 
nor that of KNO, is sufficiently trustworthy to warrant any 
