[360] An elaborate treatment of this problem is given by Walker, ‹Z. phys. Chem.›, «49», 82 (1904), «51», 706 (1905). [361] Kohlrausch and Heydweiller, ‹Z. phys. Chem.›, «14», 317 (1894). [362] See the table, p. 104. [363] See p. 53 and van 't Hoff's remarks, ‹ibid.› [364] This suggests a much broader, natural definition of a base than the conventional one. All salts of very weak acids, to a certain degree, which is determined by the weakness of their acids, do exactly what the ordinary bases do, ‹e.g.› neutralize acids. Metal derivatives of acids weaker than water, metal amides, like Zn(NH_{2})_{2}, metal alkyls, like zinc methyl, Zn(CH_{3})_{2}, react more vigorously than the hydroxides do, ‹e.g.› in neutralizing acids, and water attacks them and acts upon them, exactly as ordinary acids interact with metal hydroxides. We have, for instance, Zn(CH_{3})_{2} + 2 HOH → Zn(OH)_{2} + 2 CH_{4}. [365] See footnote, p. 177. Similar considerations apply to the conventional definition of an acid. [366] The symbols in «heavy type» indicate the chief components of the final system. ‹Vide› Smith's ‹General Chemistry for Colleges› and ‹Inorganic Chemistry›, for the form of equations used. [367] Emich, ‹Ber. d. chem. Ges.› «40», 1482 (1901). [368] Arrhenius, ‹Z. phys. Chem.›, «5», 16 (1890); Shields, ‹ibid.›, «12», 167 (1893). [369] See below for the corresponding equation, developed by Walker for a salt of a weak base and a strong acid. [370] Potassium sulphate, K_{2}SO_{4}, reacts ‹faintly› alkaline in aqueous solution, the ‹secondary› ionization of sulphuric acid (table, p. 104) being somewhat weaker than the ionization of potassium hydroxide. We have: K_{2}SO_{4} + HOH ⇄ KHSO_{4} + KOH or SO_{4}^{2−} + HOH ⇄ HSO_{4}^{−} + HO^{−}. [371] Walker, ‹Z. phys. Chem.›, 4, 319, (1889); Arrhenius, ‹loc. cit.›; Bredig, ‹ibid.›, «13», 321 (1894). [372] Arrhenius, ‹loc. cit.› [373] See p. 183. [374] Arrhenius developed the relation for aniline acetate, ‹loc. cit.› [375] Putting ‹x› = [Acid] = [Base], we have [Salt] = (0.1 − ‹x›), and (0.1 − ‹x›)^2 / ‹x›^2 = (7E−10)^2 / 1.2E−14. Then (0.1 − ‹x›) / ‹x› = 0.0064 and ‹x› = .09935, which is 99.35% of the total salt used. The degree of ionization, α, of the salt, in the extremely dilute solution, is taken to be 100%. [376] See the equations for K_{Base} and K_{Acid}, on p. 184, and their premises. [377] See p. 172. The concentration of water may be considered a constant and is included in K_{Acid} (and K_{Base}, below). [378] Only the ‹primary› ionization (of aluminium hydroxide) is considered in the text, because only that is involved, as a rule, in the neutralization of very weak bases by very weak acids (see footnote 2, p. 194). The relations are also simpler and clearer, if we limit the discussion to the formation of a salt AlO(AlO_{2}). [379] See the similar equation, p. 185.