ON THE SPECIFIC HEAT OF AQUEOUS SOLUTIONS. 
137 
proportions of both these sets of molecules are progressively reduced, and the most 
concentrated solutions become the simplest. Water itself" must be regarded as a 
ternary mixture (Bousfield and Lowry and others, ‘ Trans. Farad. Socy.,’ G, 1-49, 
1910). A highly concentrated solution may be approximately a binary mixture. 
Hence it results that we may have very simple laws for some properties of" concen¬ 
trated aqueous solutions, which become quite complex for dilute solutions. For 
instance, the law of osmotic pressure becomes quite simple for concentrated sucrose 
solutions, whilst for dilute solutions at low temperatures it is altogether abnormal 
(Bousfield, ‘Trans. Farad. Socy.,’ 13, 1917). This abnormality disappears in the 
7° ' 20° 
case of sucrose at about half-normal concentration. This branch of the subject is 
further considered in Sections 19 and 24. It appears to be a general rule with 
reference to the laws which govern the temperature variations of the physical 
properties of aqueous solutions that they are more simple for concentrated than for 
dilute solutions. 
15. The Relation between Specific Heat and Density .— Thomsen (' Thermo- 
chemische Untersuchungen,’ I., 52, 1882) observed the close relation between the 
specific heats and densities of solutions, though he did not define it with precision, 
perhaps because his density values were not of a high order of accuracy. For the 
purpose of elucidating the matter the series of Nad solutions at 20° C. mean 
t 2 
