78 Mr Oaley, Magnetic Susceptibility with Temperature. 
for this reason that the linear relation is more satisfactory for 
low concentrations than for high concentrations. 
If we take the complete expression deduced by the above theory — 
X= x +B+C3 
then we have a relation between the susceptibility and the 
absolute temperature which holds for all concentrations, the 
agreement, with the exception of the two values cited above, 
being such as to give values within the limits of experimental 
error. Jaeger and Meyer do not state the amount of their 
expec uineniae! error, but it is difficult to get nearer to the true 
value than $°/, for the stronger solutions and 1 °/, for the 
weaker solutions, especially when working at the higher tem- 
peratures. 
The nature of the constant B is of greater importance than a 
mere representation of numerical values. It will be seen that this 
quantity, which is constant for any particular concentration for a 
range of temperature from 0° C. to 80°C., but varies as the 
concentration varies, throws some light on the variation of the 
constitution of the liquid state with change of temperature. 
The expression obtained for B (p. 73) is . 
fai 
B= (3 top. Cp) + (Ftp 8Mp. Mp). 
This quantity does not vary erratically with the concentration, and 
it has a higher value for the higher concentrations than it has for 
the lower ones. Any factor of the type mp.fp 18 essentially 
positive, and as 6M, is negative for any particle of type p, the 
second term of B must necessarily be negative. Further, we know 
that over a wide range of concentration there is no appreciable 
change of diamagnetic susceptibility due to the variation of com- 
plexity of the molecular groups*, and therefore we may regard 
the second term in the expression for B as a negative term which 
admits of a negligibly small variation only, as we pass from one 
concentration to another. This term has a value which is very 
little different from the value of the susceptibility of pure water 
(approx..— 7:0 x 107”). 
The first term may be positive or negative. Any factor of the 
type M%pCpy 1s necessarily positive, but v, may be positive or 
negative—positive if the number of particles of type p is increasing 
and negative if the number is decreasing as the temperature is 
raised. As we have shown that the second term is nearly constant 
and has a small negative value we attribute the large positive 
values of B, for the higher concentrations, to particular values 
* Townsend, Phil. Trans. Roy. Soc., Vol. 187, A. p. 543, 1896. 
