ON SOLUBILITY. 455 



perature, it was found to be a function of the quantity of potassium 

 chloride present; the quantity of tartrate precipitated, when this salt is 

 only present in small quantities, being equivalent to the quantity of 

 chloride added. For solutions containing more KC1 than potassium 

 hydrogen tartrate, the expression Qi = 0'05 + 0'000005 t 3 / t/lc was found 

 to hold: in which fe = potassium in form of chloride, Qt = quantity of 

 salt in 100 parts of solution at t°. This relationship was found to 

 hold also for the bromide, iodide, chlorate, and nitrate. 169 In other 

 words, the effect depends solely on the weight of potassium present, 

 and is independent of the nature of the acid. 



Blare z lb9 also found that successive additions of small quantities 

 of potassium chloride to a saturated aqueous solution of potassium 

 sulphate precipitated the' sulphate, but the sum of the salts in solution 

 continually increased until a reverse action took place. 



Similar observations were made by Engel 17 ° on the influence of 

 alkali bases on the solubility of alkali salts. He found that sodium 

 hydroxide added to a saturated solution of sodium chloride or sodium 

 nitrate, or potassium hydroxide added to a saturated solution of 

 potassium bromide, potassium iodide, or potassium nitrate, precipitated 

 the salt originally in solution approximately in agreement with the rule 

 that 1 molecule of salt is precipitated for each molecule of anhydrous 

 oxide — (Na,0 or K 2 0) — that is added. 



Experiments by Blarez 172 on the solubility of potassium chlorate 

 as influenced by potassium hydroxide and other salts indicated that this 

 more sparingly soluble salt behaves in the same manner as the other 

 potassium salts previously studied. 



1Rq „ An attempt was made by Behrend 192 to ascertain whether 



the application of the gas laws to solutions, as made by Van't 

 Hoff, was valid for the case where a double compound becomes resolved 

 into its two components when dissolved in a liquid. As affording 

 evidence to this end, the results recorded leave much to be desired. 



Meyerhoffer ig& examined the system CuCl 2 ,2H 2 0,2KCl + KCl and 

 criticised the work of Trevor [1891] on the solubility of copper sulphate 

 with potassium sulphate. 



ftQ Noyes'- 03 criticised Arrhenius' * assumption that all binary 



salts are equally dissociated in solution, and not only did he quote 



Arrhenius' own figures to show this, but stated that he himself had 



found the solubility of potassium tartrate to be reduced to a greater 



extent by KC1 than by KN0 3 , and still less reduced by KC10 3 . 



Roozeboom's conclusions were criticised by Fock, 206 who com- 

 mented on the lack of data given by this author. He gave his results 

 for the solubility of potassium sulphate in presence of ammonium sul- 

 phate ; no proportionality being found between the molecular percentage 

 of one constituent — ammonium sulphate — and the molecular percent- 

 age of that constituent in the mixed crystal, nor was it regarded as 

 possible that there should be any such proportionality. 



An extension of the study of the influence of added salts on the 



* Zeit. phyaikal. Chem., 11, 391. 



