3 
Part IT. On Aqueous Solutions. 89 
and ferric nitrate. Taking into account the variation of dia- 
magnetic susceptibility with temperature, it has been shown that 
the numerical representation of the results of Jaeger and Meyer is 
satisfactory, and, with the exception of two cases, specially referred 
to, the relation proposed represents the observations to within the 
limits of experimental error. A solution of ferric chloride, 2°23 
normal, whose susceptibility expressed by the relation y = = +B, 
appeared to be due to an abnormal molecular constitution, was 
examined in order to see if its viscosity varied abnormally as the 
temperature was changed. Evidence of such an abnormal variation 
has been obtained. The abnormal molecular constitution of such 
a solution is further supported by determinations of the molecular 
lowering of the freezing point. 
The general theory developed in this paper includes the special 
ease of water. The variation of molecular association in water 
with change of temperature affords a ready means of accounting 
for the variation of its diamagnetic susceptibility as the tempe- 
rature varies, but we are not justified in taking a linear relation 
between the susceptibility and the temperature since we have no 
proof that the molecules of water do not possess a paramagnetic 
property smaller than the diamagnetic susceptibility and obscured 
by it at ordinary temperatures. Unless we suppose that the 
association modifies the magnetic properties of the water mole- 
cules, it is difficult to see how the diamagnetic susceptibility of 
water decreases as the temperature increases. 
Note added Jan. 20, 1913. 
The work of Dr G. Piaggesi (I Nuovo Cimento, Ser. v, T. Iv, 
1902, p. 247) has, until now, escaped my notice. Piaggesi shows 
that for a given concentration of an aqueous solution of ferric 
chloride, ferrous sulphate, ferric nitrate, manganese chloride, 
manganese sulphate, manganese nitrate, cobalt chloride and 
nickel chloride, the product of susceptibility and absolute tem- 
perature is nearly constant. 
