Chapter XV: has been studied

[151] Kablukoff, Z. ‹phys. Chem.›, «4», 430 (1889). See also
Nernst, ‹Theoretical Chemistry›, p. 373.

[152] In view of the low order of accuracy of the data, and of the
approximate method of calculation, this result is only qualitative,
but even with an error of 10^2 to 10^4 the argument in the text
would hold.

[153] For hydrogen under atmospheric pressure, the equilibrium
ratio, [Zn^{2+}] / [H^{+}]^2, is, approximately, 10^{27}.

[154] ‹Vide› Sackur, ‹Z. Elektrochem.›, «11», 387 (1905).
Kahlenberg holds a different view; ‹ibid›.

[155] The ‹negative› results obtained with aluminium and magnesium
are possibly more interesting than the positive action observed
with zinc, but their inactivity ‹may› be due to thin films of
protective chloride or oxide or to a passive condition (‹vide›
Smith's ‹Inorganic Chemistry›, pp. 723, 753; ‹College Chemistry›,
p. 475).

[156] The work of Ostwald, Arrhenius, Nernst and many others shows
conclusively that the liberation of hydrogen by metals and the
precipitation of metals by one another is a function of ‹ion›
concentrations (Chapter XIV). ‹Vide› Nernst, ‹Theoretische Chemie›
(1905), p. 245.

[157] See above.

[158] In a 0.1 molar solution of potassium cyanide, the potassium
hydroxide formed by the decomposition of the cyanide by water is
approximately 0.0013 molar and the concentration of hydrogen-ion
is reduced to 10^{−11} (Chapter X), a value roughly of the same
order as that calculated above as a possible concentration of
hydrogen-ion in a benzene solution of hydrogen chloride. In
spite of this small concentration of hydrogen-ion in the cyanide
solution, the reactions in which it is involved are, as far
as known, completed in a few moments. Only for much smaller
concentrations of ions have any doubts as to their ‹direct action›
been aroused; in Chapter XII this question, as raised by Haber,
is discussed for concentrations of ions of the order of 10^{−23}.
Haber considers that ionic concentrations of 10^{−14} can still
account for very fast actions.

[159] ‹Cf.› Abegg., ‹Theorie der Elektrolytischen Dissociation›
(1903), 255; Lehfeldt, ‹Electro-chemistry› (1904), 87.

[160] There is probably ‹minimal› ionization in all these cases,
especially in the case of ammonia (NH_{3} ⇄ NH_{2}^{−} + H^{+}),
but not enough to yield a sufficient supply of hydrogen-ion to show
its common properties.

[161] ‹Vide› Jorgensen, ‹J. prakt. Chem.›, «16», 349 (1877).

[162] See Chapter XII in regard to the stability of (PtCl_{6}^{2−})
as a complex ion.

[163] Freshly prepared solutions must be used.

[164] See Chapter XII as to the decomposition of the "complex ions."

[165] K^{+} and CN^{−} are ‹colorless› ions. The yellow color of
the ion moving to the positive electrode shows the presence of the
iron in it—a fact that can be confirmed by testing the solution
round the anode for ferricyanide by the method discussed further on
in the text.

[p090]