432 HEPOKTS ON THE STATE OP SCIENCE. 



amount of gas- in solution was found by weighing the whole and making 

 a correction for the gas unabsorbed. 



III. A. — "Physical Nature of Solvent. 



By far the major portion of the work published on the subject of 

 solubility has reference to cases where water was the solvent used. 

 More recently, however, it has been recognised that a true explanation 

 of the phenomena of solubility will be more readily arrived at from 

 a study of the behaviour of substances towards solvents in general 

 rather than towards water or any other solvent in particular. 



There can be little doubt that solubility phenomena involve the 

 reciprocal interaction of solvent and solute, be such action physical, 

 chemical, or physico-chemical in nature. For this reason an attempt 

 has been made to classify under this section, A, work relating to the 

 influence of the physical nature of the solvent, and B, the influence of 

 the chemical nature of the solvent on the solubility of substances. 



Dalton 2 announced that the total pressure of a mixture of 



gases occupying a given space is the sum of the partial pressures 



exerted by the constituents of the mixture. This means the solubility 



1876. °f a S as m another gas becomes simply a question of admixture. 



1 q7r) Some deviations from this were, however, observed by Andrews 63 



and also by Regnaiilt. 76 



The phenomenon of a solid dissolving in a gas was examined by 



Hannay and Hogarth 75 ; they employed the sulphur halides as solutes 



and the solvents used were alcohol, ether, carbon bisulphide, &c, kept 



well above their critical temperatures. 



They carried this work further, 80 making use of potassium 

 1880. iodide and cobaltous chloride dissolved in alcohol vapour at 

 300-320° C. From their results it appeared that the absorption 

 spectrum of a substance dissolved in a gas was practically identical with 

 the absorption spectrum of that substance when dissolved in the liquefied 

 gas. 



Although Ramsay 81 threw doubt upon this work, suggesting that 



these authors had merely observed the phenomenon of solubility of 



a solid in a hot liquid, the observations were substantiated by Lenier. 62 



The behaviour of partially miscible liquids was most thoroughly 



investigated by Konowalow,* 7 the work embracing the influence 



L ' of pressure and temperature on the mutual solubility of water and 



respectively formic acid, propylic alcohol, methylic alcohol, and ethylic 



alcohol. Similar work on the solubility of one liquid in another 



(mutual solubility) was carried out by Alexejeff, lls who found the 



' solubility varied with the cohesion : the greater the cohesion, the 



greater the solubility. 



Q Carnelley and Thomson 13G found a parallel relationship existed 



between the solubility of acids and of their salts which was not 

 disturbed by varying the nature of the solvent employed ; further, that 

 the ratios of the solubilities of two organic isomerides in any solvent 

 is very nearly constant, and is therefore independent of the nature of 

 the solvent used. 



With certain solvents AlexejefJ 11S had previously recorded that 



