462 REPORTS ON THE STATE OF SCIENCE. 



solvent as the inferior limit : all intermediate points as loci of the 

 melting-points of mixtures of solvent and solute. 



That union, or interaction, does take _place between solvent and solute 

 seems also to follow from the work of Lobry de Bruyn. 1 ' 19 This author 

 found certain hydrated sulphates of dyad metals were soluble to a con- 

 siderable extent in methylic alcohol, but the solution obtained was 

 unstable, depositing the salt again on standing : the addition of a few 

 drops of water accelerated the deposition. The salt separating from 

 such a solution generally contained less water than that originally held, 

 and, in some cases, a partial replacement of water by methylic alcohol 

 was found to have taken place. 



The view expressed by Noyes {vide this Section, 1892), more parti- 

 cularly that the degree of dissociation derived from measurements of 

 solubility is more trustworthy than that obtained from measurements 

 of electrical conductivity, was disputed by Arrhenius. 201 This 

 was based upon his observations that the electrical conductivity 

 of a salt differs greatly when calculated from solubility measurements 

 according as the sparingly soluble salt with which it is present is more 

 or less soluble. The law of mass action upon which the calculation 

 is based was not considered applicable to strongly dissociated 

 electrolytes. 



Noyes and Clement 207 found the solubility of KHC 4 H 4 6 — 

 potassium hydrogen tartrate — was variously decreased by the 

 addition of potassium salts of halogen acids and by nitric acid, while 

 potassium acetate and hydrochloric acid caused an increase in the solu- 

 bility of tartrate. These effects were ascribed to the different degree 

 of ionisation of the added salt. 



From measurements of the solubility of mercuric chloride, bromide, 

 and iodide, and of iodine in carbon bisulphide (vide Section V. A (i), 

 1894) Arctoivski 209 was led to regard solutions as ill-defined molecular 

 compounds of solute and solvent. He supposed that when one sub- 

 stance does not dissolve in another it is because the two substances are 

 incapable of forming such molecular compounds. He took great excep- 

 tion to the view that water as a solvent is an inert substance. 210 



These conclusions were supported by the recorded work of 

 Linebarger, 211 wherein it is shown that mercuric chloride and sodium 

 chloride combine together, giving a double salt which is soluble in 

 ethylic acetate, and that the solubility of this complex is first of all 

 decreased by the addition of small quantities of NaOl, and, as the 

 amount of NaOl increases, the solubility of both salts becomes increased. 



Holleman and Antusch 22 ° contributed an extension of Bodlander's 

 work, making use of solid .non-electrolytes dissolved in aqueous solu- 

 tions of ethylic alcohol. Among the substances used may be mentioned 

 p-aeettoluidide, a-acetnaphthalide, and also phenylthiocarbamide : 

 Bodlander's * formula was not found to hold for these cases. On the 

 addition of water to the alcohol the solubility usually underwent a 



* To this Bodlander ' 2m replied that in some cases he found from Holleman and 

 Antusch's values that his formula did hold provided the substance was only soluble 

 iu water and not in alcohol. 



