Part II. On Aqueous Solutions. 75 
observed that the representation of the susceptibility by the 
relation 
A 
X= a +B 
holds good so long as we are dealing with concentrated solutions 
and is preferable to the linear relation 
¥ =%(1—«.?). 
But for weak solutions the linear relation is more satisfactory 
than the hyperbolic one. We see, on referring to p. 73, that this 
is precisely what would be expected. The approximate form 
x=2 +B 
has been used instead of the accurate form 
— - +B+C3 
for the representation ; and the term OS, which deals with the 
variation of the diamagnetic susceptibility with the temperature, 
has been neglected. So long as we are dealing with strong 
solutions the variation of the diamagnetic susceptibility with the 
temperature is insignificant compared with the large value of the 
paramagnetic susceptibility, but for weak solutions this is not 
the case, and it is necessary to take into account the term CS. 
The figures show that for the weaker solutions the calculated 
value of y on the assumption that x=—+B is in general lower 
than that calculated from the equation y=y,(1 —e.¢), and the 
experimental value lies between the two calculated values. 
Consider the variation of the susceptibility of water with the 
temperature. Although different observers have obtained different 
values for the absolute susceptibility of water, they are all in 
agreement that the susceptibility decreases as the temperature 
increases. This is equivalent to saying that water becomes 
more paramagnetic as the temperature increases. We shall take 
the expression 
Xw = — 0°750 (1 — 0:00164¢) 10 
as representing the variation of the susceptibility of water with 
the temperature. 
Xwo _ 1 ae 
ee mS O64 
Xwin 18 20°/, less than y,. The maximum correction to be 
applied to the figure in column 6 in order to take this variation 
