852 REPORTS ON THE STATE OF SCIENCE.—1912. VII. 
the substance is soluble in water; if it is less than 3°5, then it is not 
soluble. 
An important paper on solubility was contributed by Levin.2°4 He 
critically reviewed previous work and came to the conclusion that non- 
electrolytes do not appreciably change the solubility of a substance. 
With regard to salting-out phenomena, he was not in agreement with 
the conception of an ‘internal pressure,’** nor with Rothmund’s as- 
sumption of a combination between solvent and solute, but supposed the 
lowering of solubility to be due to the mutual action of the two solutes 
upon each other. Trevor?"! published a purely mathematical investi- 
gation of certain solubility graphs. 
Shinn *°° made the important observation that in passing from liquid 
ammonia to amylamine as solvent for salts there is a reversal of the 
1907 usual relation between molecular conductivity and dilution. For 
* example, in ethylamine and amylamine the molecular conduc- 
tivity decreases with increased dilution, a fact which, from the stand- 
point of the electrolytic dissociation theory, was considered to be inex- 
plicable. 
As the result of studying the precipitation of salts from solution by 
non-electrolytes and by electrolytes under identical conditions Armstrong 
and Eyre *°° observed a general similarity in the behaviour of these sub- 
stances towards electrolytes in solution. From solubility measurements 
they concluded that the condition in which salts exist in concentrated 
aqueous solutions is different from that which they assume when in the 
presence of a considerable quantity of a precipitant. 
Philip *°” expressed the opinion that substances when dissolved in 
water are frequently hydrated, and he considered that the degree of 
hydration of an added substance could be calculated from the difference 
between the solubility of a gas in water and in a solution of the added 
substance. + 
From an examination of the action of salts in causing mixed liquids 
to separate into layers, Smirnoff *17 supposed the ‘ions’ of the solute 
become associated with the solvent. Bingham °° investigated a similar 
phenomenon—namely, the miscibility of liquids—and suggested that 
this is dependent upon the attractions between the particles, and he 
adduced evidence to prove that the molecular attractions are inversely 
proportional to the molecular volumes. 
Ostromysslensky *'* classified organic solvents according as (a) their 
solvent power is independent of the constitution of the solute—e.g. 
water, ether alcohol, &c.—or (b) their constitution must be related to 
that of the solute. Magie*°* pointed out how the properties—heat 
capacity and volume of a solvent—are changed by the presence of a 
solute and advanced an association theory of solutions. 
Parsons ?°* drew attention to the case of the dissolution of a sub- 
stance in a mixture of two substances with one of which it is immiscible. 
It was argued that a solid, when in solution may, and frequently does, 
act towards other solutes exactly as if it were a liquid miscible with 
the liquid in which the second solute is itself soluble. The assumption 
* Vide Part II.’Section V. C. (ii) R. 200 and 201. 
+ Vide also a supplementary publication by the same author.“ 
