ON SOLUBILITY. 457 



the two solvents. Although unsuccessful in this direction they ascer- 

 tained that when a substance is simultaneously in the presence of two 

 solvents, the quantities dissolved by equal volumes of each have a 

 constant ratio — coefficient of distribution — which is independent of the 

 relative volumes of the solvents, but varies with the degree of concen- 

 tration and with the temperature.* 



A very thorough investigation of the behaviour of partially miscible 



1881 li( l lU( ^ s was carr i e d out by Konowalow . 87 This work embraced 



the influence of pressure and temperature on the mutual 



solubility of water and respectively formic acid, methylic, ethylic, and 



propylic alcohols. 



1884 Guthrie l0S studied the solubility relations of partially mis- 



cible liquids, as, for example, ethylic alcohol and carbon bisul- 

 phide, alkylamines and water, &c. 



Having previously shown that the mutual solubility of substances 

 ft _ is not always increased by rise of temperature,! Alexejeff ns 

 came to the conclusion that mutual solubility phenomena are not 

 as simple as the hypothesis of Dossios supposes (vide Section VIII., 

 1867). From numerous experiments it was concluded that liquids 

 which dissolve one another appreciably at ordinary temperatures mix 

 completely at temperatures considerably below their absolute boiling- 

 points, there being no essential difference between the laws of mutual 

 solubility of liquids and solids. This conclusion was experimentally 

 confirmed. 

 _„„ Nernst 162 extended the application of the law of distribution 



of a substance between two solvents, showing that this was 

 dependent upon the substance having the same molecular weight in both 

 solvents. He suggested this as a useful method of ascertaining mole- 

 cular weights of compounds. 



1RQ1 A publication by Riecke 174 on the thermal potential for dilute 



solutions contains results which are in agreement with experi- 

 mental data for the distribution of a substance between two solvents, 

 and also for the diminution of solubility of a substance by the addition 

 of a second substance. These results, which were arrived at mathe- 

 matically, are based upon the application of Gibb's equation to the case 

 of dilute solutions. 



From the observations of Alexejeff on the solubility of aniline in water 

 and water in aniline at various temperatures, Masson 17S found experi- 

 mental evidence in favour of the view that there is complete analogy 

 between the dissolution and the vaporisation of solid substances. 



Berthelot's work on the distribution of a substance between two non- 

 miscible solvents was extended in theory by Aulich 179 to the case where 

 four substances were present in chemical equilibrium — two salts with 

 like base and different acids, and also the acids of those salts. This 

 author discussed the relationship between the affinity coefficient and 

 the distribution coefficient of this system. 



Kiister 183A published an extension of his previous work J on the 



I * See also IV. B. f Vide also Bull. Soc. Chim. (2), 42, 329. 



J Zeitschr. f. •physik. Chem. (1890), 5, 601. 



