836 REPORTS ON THE STATE OF SCIENCE.—1912. V.c. iii. 
salts concerned, they arrived at important conclusions. From time to 
time their results appeared in a series of papers dealing with the ‘ For- 
mation of Oceanic Salt Deposits,’ of which a good summary * is to be ~ 
found in a publication by Van’t Hoff ?*°* himself. Work upon the 
1905 formation and solubility of double salts in aqueous solution was 
* also published by Koppel 2? who investigated the conditions of 
-existence of salts of the type Na,R” (SO,),, « H,O, and by Rimbach 
and Grewe 2?! who studied the double salts formed of cadmium halides 
with the halides of potassium, ammonium, and rubidium. 
Various examples of an increase in the solubility of slightly soluble 
salts when in the presence of more soluble ones have been made 
known. Cameron and Brown 2*4 found that ammonium chloride and 
ammonium nitrate both increase the solubility of calcium sulphate, 
and Geffcken4* found that salts of the alkali metals increase the 
solubility of lithium carbonate, and according to the observations re- 
corded by Kiister and Dahmer,*47 barium sulphate is many times more 
soluble in concentrated solutions of chromic chloride than in water 
alone. In the course of a study of the equilibrium relationships 
between: the modifications of chromic chloride hexahydrate, Rooze- 
boom 24° observed that the solubility of both green and violet varieties 
is lowered by the addition of hydrogen chloride. 
The ‘solubility product’ for silver nitrite was calculated by 
Naumann and Riicker 22° on the assumption that it is a salt which is 
completely ionised, but on this basis, their results for the solubility 
of that salt when in presence of silver nitrate were somewhat anoma- 
lous. Abegg and Pick 224 pointed out that silver nitrite is only ionised — 
to the extent of 55 per cent. at 25° and, making this correction, they 
showed that the ‘ solubility product’ is not affected by silver nitrate. 
From considerations based upon the dissociation theorem, 
Philip 22° was led to anticipate that the solubility of sparingly soluble 
acids would be increased by the presence in solution of sodium salts of 
weak acids. This he was able to confirm, inasmuch as the formate, — 
acetate, and butyrate of sodium were shown to increase the solubility of 
cinnamic, benzoic, and other acids. Furthermore, the order of the 
increase of solubility is dependent upon the strength of the acid. Work 
of a somewhat similar character was carried out by Hoffmann and 
Langbeck,2*° who studied how far the addition of electrolytes changed 
the solubility of benzoic and allied acids. The initial effect was gener- 
ally found to be an increased solubility of the acids, and finally their 
solubility was lowered by further addition of electrolyte. 
An investigation of the change of solubility of calcium sulphate-when 
1906 dissolved in solutions of ammonium sulphate was carried out by 
’ Bell and Taber.272, These authors were able to detect the pre- 
sence in solution of a double salt, the formation of which was held t 
* Brit. Assoc. Report, 1901, Glasgow (Section B'), by E. F. Armstrong, entitl 
‘The application of the Equilibrium Law to the separation of crystals from comple 
salt solutions, and to the formation of oceanic salt deposits,’ summarises this wor 
and contains a useful explanation of the construction and interpretation of t 
diagrams referred to above. 
