248 PROPERTIES OF ELECTRICALLY CONDUCTING SYSTEMS 



ture, while in other cases the solubility effect is relatively independent of 

 temperature. In the presence of nitric acid, the coefficient for oxygen 

 increases from 4 to 8 per cent, as the temperature falls from 25 to 15. 

 In the presence of hydrochloric acid the coefficient increases slightly, 

 while in the presence of sulphuric acid the coefficient changes but little. 

 In the presence of sodium chloride, the coefficient is practically identical 

 at the two temperatures. The solubility of nitrous oxide appears to vary 

 less than that of oxygen as the temperature changes. 



The order of the electrolytes in terms of their solubility effect is 

 practically the same for different gases. Indeed, in many cases, the 

 solubility coefficients for different gases are very nearly the same for the 

 same electrolyte. An inspection of the tables will show that, in general, 

 the order in which the electrolytes appear is the same. In certain cases, 

 however, the solubility effects show an influence due to the nature of the 

 dissolved gas. For example, in a 1.0 normal solution, the solubility 

 coefficient for hydrogen in the presence of nitric acid is 4.9, that of 

 oxygen is 4, and that of nitrous oxide is 1 per cent. The negative sign 

 indicates that the solubility is increased on addition of the electrolyte. 

 The solubility effect is smallest in the case of the acids and is greatest in 

 that of the bases. The solubility coefficients for the salts are, in general, 

 slightly smaller than those for the bases. 



In Table 1T XCVII are given values of the percentage equivalent solu- 

 bility depression for a variety of substances in the presence of different 

 electrolytes. A comparison of the results collected in this table shows 

 that the order of electrolytes as regards their effect on the solubility of 

 different substances is practically identical throughout. This is particu- 

 larly true in the case of those substances where reaction with the -electro- 

 lyte is not to be expected. The smallest effect for typical salts is ob- 

 served in the case of ammonium nitrate. However, any general relation 

 between the nature of the electrolyte and the nature of the solubility 

 effect cannot be established. The action is specific in character. 



With a few exceptions, the addition of an electrolyte to a solution 

 of a non-electrolyte in water causes a depression in the solubility of the 

 non-electrolyte. This effect, which has been called a "salting out" 

 effect, is not, however, characteristic of electrolytes alone. For example, 

 the percentage equivalent solubility depression of hydrogen in water in 

 the presence of sugar at normal concentration is 32. Similarly, the 

 equivalent depression of hydrogen at the same concentration at 20 is 

 9.2 for chloral hydrate. The depression for sugar is greater than that for 

 most salts, while that for chloral hydrate is greater than that for the 



"Euler, Ztschr. f. pliys. CJiem. 1$, 310 (1904). 





