[217] The calculation of the condition of equilibrium can be made, with sufficient accuracy for our purpose, as follows: The denominator 0.9958 in the original proportion, being near its limit (its highest possible value is 1 in a molar solution), cannot change appreciably. Consequently, when the one factor in the numerator, [CH_{3}CO_{2}^{−}], is made 0.53 / 0.0042, or 126 times as large as it was, the other factor, [H^{+}], to maintain a constant proportion, must be made 1 / 126th of its original value and 0.0042 / 126 = 0.000,034. For more exact work, the new concentrations of the three components may be found by solving a simple quadratic equation. [218] Küster, ‹Z. für Elektrochem.›, «4», 110 (1897). [219] See note, p. 79. [220] See Part III for the application of this principle to ammonium hydroxide and its experimental confirmation. (‹Cf.› Arrhenius, ‹Z. phys. Chem.›, «2», 28 (1888); Stieglitz, ‹Am. Chem. J.›, «23», 406 (1900).) [221] For instance, in the first place, the action of 0.1 mole of HCl on 0.1 mole of C_{2}H_{3}O_{2}Na, dissolved in a liter of water, and, in the second place, the action of 0.1 mole of NaOH on 0.1 mole of NH_{4}Cl, in a liter of water, may be considered. The strong electrolytes (HCl, C_{2}H_{3}O_{2}Na, NaCl, NH_{4}Cl, NaOH) may be taken to be (roughly) 80% ionized. From the concentrations given and the constants involved, the direction and the presumable intensity of the main change in each of the two cases should be determined. [222] Instances of such displacement are given in the footnote of the previous paragraph. [223] ‹E.g.› 50 c.c. of 0.2 molar solutions. [224] Mercuric cyanide and mercuric chloride are largely present in aqueous solution as [Hg(CN)_{2}]_{2} and [HgCl_{2}]_{2}; see Chap. XII. [225] See Chapter VIII in regard to this proof that mercuric sulphide is less soluble than mercuric oxide and in regard to the question how, by a continuous disturbance of the equilibrium conditions, all the mercury may be precipitated from the cyanide solution as the sulphide, in spite of the very slight degree of ionization of the cyanide. [226] The chloride is, however, sufficiently ionized to make possible the precipitation of the very insoluble silver chloride, when silver nitrate is added to its solution. [p118] CHAPTER VII «PHYSICAL OR HETEROGENEOUS EQUILIBRIUM.—THE COLLOIDAL CONDITION»