828 REPORTS ON THE STATE OF SCIENCE.—1912. V.c. ii. 
results of this work, although of great interest, do not admit of any 
general conclusion being drawn. 
Schroder *** measured the solubility of potassium chloride in aque- 
ous pyridine solutions of various compositions. At 10° C. he found the 
solubility of the salt to increase as the proportion of water increases ; 
at higher temperatures complications arise owing to the separation of 
the liquid into two layers. 
Two communications by Herz and Kuhn ***: #87 contain their records 
and results of determining the solubility of mercuric halides and cyanide 
and of some halides of the alkali metals and of ammonium, in mixtures 
of ethylic and methylic, propylic and methylic, and propylic and ethylic 
alcohols. Assuming that each constituent of the solvent exerted its 
solvent power independently, the solubility was calculated and com- 
pared with the solubility value found by experiment. The calculated 
and observed values were found to agree within 10 per cent. only in 
the case of mixtures of ethylic and propylic alcohols. In other cases 
the divergence was greater. 
In the same year Kéfler °*® published his results of measurements 
of the absorption coefficient of radium emanation in solutions of 
metallic salts. 
From an examination of the influence of various organic substances 
upon the solubility of salts which are sparingly soluble in water, 
Rothmund *** concluded that the lowering of solubility thus occasioned 
is not proportional to the concentration of the substance added. He 
observed the relationship '/2 log = = K (a constant). In this ex- 
pression n=molecular concentration of the added substance; 1,= 
solubility of salt in pure water; 1=solubility of salt in mixed sclvent. 
The value of K was found to depend upon the nature of the organic 
substance added; with the sugars, which raise the solubility of salts, 
the value of K is negative. The correctness of this author’s conclusions 
was called into question by Hudson.*4%4 
1909 Further work on this subject enabled Rothmund**" to 
* conclude that the diminution of solubility of a salt brought about 
by the addition of a non-electrolyte is so much the greater the more 
effective the salt is itself in lowering the solubility of non-electrolytes. 
This view was based upon the behaviour of a large number of different 
substances in changing the solubility of lithium carbonate, silver sul- 
phate and other slightly soluble salts. Unfortunately, having adopted 
a volume-normal basis of comparison, it is impossible to accurately 
judge of the relative effect produced by the added substances. This 
author also criticised the views expressed by Hudson regarding the 
influence of non-electrolytes upon the solubility of electrolytes. 
Hudson’s *®° observations being that whilst carbamide diminishes the 
solubility of anhydrous sodium sulphate in water, it increases that of 
Glauber’s salt. To explain this he supposed the existence of anhy- 
drous and hydrated molecules; and, representing the concentration of 
these by a and h respectively, the total solubility s=a+h. According 
as anhydrous salt or hydrated salt is the equilibrator, so either a 
