854 REPORTS ON THE STATE OF SCIENCE.—1912. VII. 
pressure '* of the solution and defined it *%* as the force with which 
the solute is retained in solution. It was stated that of two substances 
1910 possessing the same internal pressure, that one is the more 
* soluble which can exert a greater cohesion pressure. The 
difference between the surface tension of a solvent and a solution was 
regarded as a measure of the cohesion pressure of the solute. 
Armstrong and Hyre*** were able to explain the results of their 
further research on solubility influence on the basis of Armstrong’s 
theory of solution.{ Precipitation of salts by alcohols was held to be 
due to dehydration changes conditioned both by the direct removal of 
water from solvent action by the precipitant, and particularly with 
neutral precipitants, by the increased proportion of ‘ hydrone ’ molecules 
produced in the water by the mechanical interposition of the precipitant 
molecules. The increased solubility of salts when in the presence of 
sugar was considered to be due to combination taking place between 
salt and sugar. 
Usher *°*4 concluded that the effect on the solubility of a gas pro- 
duced by non-electrolytes is not capable of explanation by reference 
either to the formation of hydrates in solution or deviations from the 
theory of osmotic pressure, and claimed that his results showed that, 
to express the solvent properties of solutions, any conclusions depend- 
ing on the assumption that the dissolved substance has no solvent 
power are worthless. 
Above the critical temperature 7'yrer *’° observed the solubility of a 
substance to be dependent upon the concentration of the solvent, as 
would be expected if solubility is dependent upon an attractive force 
acting between solvent and solute. He *7? was led from this observation 
to suppose that in all cases solubility is some function of the concentra- 
tion of the solvent and sought to ascertain by experiment with organic 
substances what that funetion may be. No simple general rule was dis- 
covered, however. 
According to Gibson and Denison**® the electrolytic dissociation 
theory in no way explains the facts they observed respecting the 
strength of hydrochloric acid necessary to precipitate chlorides from 
solution, and this they consider is because no account is taken of 
hydrated ions and undissociated molecules. 
Hill*** published a paper which dealt with the inconstancy of the 
1911 ‘solubility product,’ and in the following year additional dis- 
’ credit was cast on this principle by the research of Kendall.*1° 
Noyes ,*°* 4°° in conjunction with Bray *°7. #°§ and others, made an. 
investigation of the so-called laws of solubility influence and disproved 
two of them which he claimed to have established in 1895. t 
Notse.—In 1909, H. C. Jones*** published a paper entitled ‘The present 
status of the Solvate Theory,’ in which he reviewed the work done by himself 
and his co-workers during the past ten years. 
* For further information respecting the researches and the views held by this 
author, reference should be made to Ber., 17, 2304; Pfluger’s Archiv }. Physiologie, 
105, 541 and 549; 128, 419; Archiv f. Pathologie, I1., 117; Deutsch. medic. 
Wochenschrift, Nr. 28; Verh. deutsch. physik. Gesell., 6, 326; Biochem. Zeitschr., 40, 
371. 
t Vide this Section, R. 305 and 334. t Vide Part I. R. 228, 
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