834 REPORTS ON THE STATE OF SCIENCE.—1912. V.c. iii. 
Riubenbauer **° measured the solubility of the hydroxides of zinc, 
barium, tin, and lead in solutions of caustic soda of various strengths. 
With both zinc and lead a maximum solubility was detected: the 
atomic ratios being, Zn: Na=1: 3 and Pb: Na=1: 14. The diminu- 
tion of solubility with greater concentrations of caustic soda was attri- 
buted to the formation of a less soluble form of hydrate owing to 
dehydration by the caustic alkali. 
Noyes and Kohr'*? studied the solubility equilibrium between 
silver chloride, silver oxide, and solutions of potassium chloride and 
hydroxide. The values found by these authors for the solubility of 
silver chloride by methods of direct analysis were not in agreement 
with those found previously by Kohlrausch,* who employed the con- 
ductivity method. Arguing from their own observations, Noyes and 
Kohr concluded that silver hydroxide is not completely dissociated, as 
Kohlrausch assumed it to be when calculating his results, but is only 
dissociated to the extent of 78 per cent. 
Rothmund and Wilsmore??* contributed a theoretical discussion 
of the subject of solubility in which they dealt more particularly with 
the reciprocal nature of solubility influences. 
Among those who continued the experimental investigation of the 
changes in solubility of salts when various proportions of acids are added 
to the solvent water, mention must be made of the work of Cameron and. 
1903 Breazeale.17° These authors found that with low concentra- 
* tions of sulphuric acid the solubility of calcium sulphate is 
greater than in water only. An explanation of this fact was offered 
by the authors, but it was not subjected to experimental verification. 
Soon afterwards, Cameron and Seidel 1*! published work on the solu- 
bility of magnesium carbonate in aqueous solutions of certain electro- 
lytes. Herz +8* carried out similar work to the above, employing boric 
acid as solute and varying the proportion of other acids, such as nitric 
and acetic acid, in the solvent water. In the case of sulphuric acid, 
nitric acid, and acetic acid he found that the solubility of the boric 
acid was diminished as the concentration of mineral acid was increased ; 
but when tartaric acid was present the boric acid became more and 
more soluble as the proportion of tartaric acid was increased. 
Herz and Muhs '*° showed that the tartrates and acetates of cal- 
cium, strontium, and barium all exhibit a maximum solubility in acetic 
acid solutions between the concentration 2.5 and 3.5 N: corresponding 
with the concentration which exhibits a maximum electrical con- 
ductivity. The fact of alkali formates being readily soluble in water 
and formic acid led Groschuff?°? to imvestigate experimentally the 
variations in solubility. He concluded that the increased solubility 
caused by the formic acid is due to the formation of acid salts, and 
he drew an analogy between hydrated salts and acid salts.1** 
Riesenfeld 1** continued his work which was commenced in con- 
junction with Abegg in the previous year,+ and published further results 
of the research on the solubility of ammonia in aqueous salt solutions as 
measured by its partial pressure. 
* Vide Kohlrausch and Rose. Part T. R. 204. + Vide R. 124. 
