Solvent. Solubility. ‹e›_{5} ‹e› : ∛‹c› Water 0.0332 75.0 50.5 Nitrobenzene 0.0020 32.2 54.8 Ethyl alcohol 0.00201 26.6 45.5 Acetone 0.00072 21.8 52.8 Amyl alcohol 0.00031 15.0 48. In view of the difficulties in determining the values for the dielectric constant, the agreement in the values of the last column must be considered satisfactory.[325] This important principle forms another striking instance of the ‹supreme influence of electrical relations in determining the behavior of ionogens in solution› (see p. 111). Since, in solutions saturated at the same temperature with a given ionogen, the degree of ionization of the ionogen is the same in both solvents, the proportion of nonionized to ionized salt is also the same. If a salt, ‹e.g.› calcium sulphate, is less soluble in alcohol than in water, the alcohol must hold less of the nonionized form, as well as less of the ionized salt, than does an equal volume of water at the same temperature. The development of further relations, of fundamental importance to analytical chemistry, with the aid of the laws of chemical and physical equilibrium and of the principle of the solubility-product, will be taken up in the study of the reactions of the various analytical groups of ions. FOOTNOTES: [291] ‹Z. phys. Chem.›, «4», 372 (1889). See also van 't Hoff, ‹ibid.›, «3», 484 (1889). [292] ‹Cf.› page 94. [293] A. A. Noyes, ‹Z. phys. Chem.›, «9», 618 (1892); Findlay, ‹ibid.›, «34», 409 (1900). [294] As foreign salts affect the ionization of poor «electrolytes» (p. 109), the ratio of equation I would hold as little for poor electrolytes, and would grow larger with an increased concentration of the foreign salts. [295] ‹Cf.› A. A. Noyes, ‹Congress of Arts and Sciences› (St. Louis), «4», 321 (1904) and Stieglitz, ‹J. Am. Chem. Soc.›, «30», 946 (1908) («Stud.»), and the references to literature given there. The empirical relation seems to hold for dilute solutions, the total electrolyte concentration of which is not greater than 0.2 to 0.3 gram-equivalent per liter, and, roughly, for concentrations not greater than 0.5 gram-equivalent per liter. [296] See Stieglitz, ‹loc. cit.› [297] Since the writing of this it has been learned that such investigations have been carried out by Harkins. ‹Cf.› ‹J. Am. Chem. Soc.›, 1911. [298] ‹J. Am. Chem. Soc.›, «32», 488 (1910). [299] Otherwise a ‹perpetuum mobile› of the ‹second class› (footnote 3, p. 12) could be constructed, which is at variance with experience. [300] This sentence is quoted from a letter from Dr. Washburn, who is at present investigating moderately concentrated solutions of electrolytes, to determine the range of concentrations in which it is possible to apply the laws of ideal solution.