ON SOLUBILITY. 449 



1875 Setschenoff 61 carried out a similar research, as did also 



Mackenzie 66 ; the former, however, went more deeply into the 



nature of the phenomena, recognising a rather marked difference 



in the behaviour of various salts ; those which exerted chemical action 



on the gas, and those which did not. 



From his own results Setschenoff 6S concluded that the ab- 

 ' sorption coefficient of carbon dioxide in pure sulphuric acid was 

 identical with that in water; the addition of water caused a rapid 

 decrease of this value to a minimum. These results he explained by 

 assuming the absorption of carbon dioxide and the hydration of the 

 acid to proceed equally. 



In the following year Draper 67 observed the non-electrolyte 

 ether was more soluble in aqueous solutions of hydrogen chloride 

 than in pure water. 



-.nan Klepl 89 found that chemically pure, dry methylic alcohol dis- 



solves anhydrous copper sulphate assuming a bluish-green colour, 

 the addition of a small quantity of water to this solution caused the 

 discharge of the colour and complete precipitation of the copper sulphate 

 as the blue hydrated salt. 



1c . ftr Ammonia was found by Giraud 116 to be a very effective pre- 



cipitant of certain salts, notably potassium sulphate, which is 

 thrown out of solution almost completely when the solution contains 

 ift«R about 30 per cent. NH 3 . Setschenoff 120 continued his work on 

 '* the absorption of gases in salt solutions, but the results he ob- 

 tained, like those of Raoult (1874), were difficult to interpret because 

 1887 °ften the gases used had some chemical action on the dissolved 

 salt. 125 Miiller 145 investigated the absorption of carbon dioxide 

 188y. j n a q ue ous alcoholic solutions and found a minimum of absorp- 

 tion at certain concentrations of alcohol; in this, and in other respects, 

 his results were somewhat analogous with those previously recorded 

 by Setschenoff. 65 



From a study of the absorption of carbon dioxide in salt solutions 

 Setschenoff 142 showed that the absorption coefficient of salt solutions 

 is smaller than that of water, and follows Dalton's law. He also came 

 to the conclusion that a salt solution is a very weak chemical compound 

 of salt and water. 



Nernst 144 published an important theoretical discussion of solu- 

 bility viewing this process as strictly analogous to vaporisation ; he 

 arrived at the conclusion that the presence in solution of a non-electro- 

 lyte does not affect the solubility of another substance in that liquid. 



Evidence running counter to this conclusion of Nernst was published 



•loni by Bodlander, 176 who found the solubility of potassium chloride, 



sodium nitrate, and potassium nitrate was affected by the presence 



of alcohol ; the relationship - — ^_= k found for sugar and alcohol (vide 



Section V. (i) 1891) was found to hold with fair approximation. 

 1892 Wegner, 197 and a little later also Roelofsen, 213 ascertained 



iRQi *' ne m fl uence °f various concentrations of alcohol on the solubility 

 " of potassium hydrogen tartrate. 

 Steiner 219 determined the absorption coefficient of hydrogen in water 



