[64] Ion = the going or the migrating particle.
[65] See Washburn, ‹J. Am. Chem. Soc.›, «31», 322 (1909), in regard to the values of ‹x› and ‹y›, the quantities of water carried by certain ions.
[66] ‹Vide› J. J. Thomson, ‹Electricity and Matter› (1905) and ‹Corpuscular Theory of Matter› (1907) («Stud.»). ‹Vide› R. A. Millikan, ‹Science›, «32», 436 (1910), on the discrete or "granular" nature of electricity («Stud.»).
[67] See ‹Millikan›, ‹loc. cit.›, as to the exact value of this "unit charge."
[68] ‹Cf.› McCoy, ‹J. Am. Chem. Soc.›, «33», March, 1911, in regard to electropositive, composite (‹i.e.› nonelementary) "metals."
[69] The symbol ε is used to designate an electron. The loss of one electron by an atom leaves a ‹unit positive charge› on the particle.
[70] In Chapter XV (‹q. v.›) the affinity of the elements for electrons and the reactions, of the nature of oxidation and reduction, depending on this affinity, are discussed in detail.
[71] J. J. Thomson, ‹Corpuscular Theory of Matter›, p. 120.
[72] A. A. Noyes (‹Carnegie Institution Publications›, No. «63», p. 351 (1907)), believes that we may have two ‹kinds of molecules›, HCl and H^{ +}Cl^{ −}, as well as the ions H^{ +} and Cl^{ −}.
[73] Modern theory thus is reverting to the Berzelius theory of chemical affinity [‹Vide› Meyer's ‹History of Chemistry› (translated by M'Gowan) 1891, 220–265, or Ladenburg's ‹History of Chemistry› (translated by Dobbin) 1900, 86, 88, etc.]
[74] To a saturated solution of cupric nitrate may be added a small amount of a saturated solution of potassium permanganate, sufficient to give a decided purple color to the mixture. Potassium chromate, as recommended by A. A. Noyes, may be used in place of the permanganate. (‹Cf.› Noyes and Blanchard, ‹J. Am. Chem. Soc.›, «22», 726 (1900).)
[75] ‹Exp.›; ‹cf.› Eckstein, ‹J. Am. Chem. Soc.›, «27», 759 (1905) («Stud.»).
[76] W. A. Noyes, ‹J. Am. Chem. Soc.›, «23», 460 (1901); Stieglitz, ‹ibid.›, «23», 796 (1901); Walden, ‹Z. phys. Chem.›, «43», 385 (1903).
[77] ‹Corpuscular Theory of Matter›, p. 130 (1907).
[78] The experiment is an adaptation of a similar one described by A. A. Noyes and Blanchard, ‹J. Am. Chem. Soc.›, «22», 726 (1900).
[79] The copper electrodes are polarized by the formation of hydrogen on the cathode, but, in the course of a few seconds, the current becomes rather constant and is then read. The polarization may be considered as simply reducing the potential of the cell, and since, within the range of concentrations of acid used,—4-molar to 1/8-molar—the polarization current does not vary markedly, as compared with the potential of the storage cell, the total potential used through the series of dilutions may be considered sufficiently constant for the purposes of the experiment. Readings are made three or four seconds after each dilution, when the polarization has been fully established. Polarization may be entirely avoided by the use of a silver nitrate solution and silver electrodes or of a cupric salt solution and copper electrodes (Noyes and Blanchard). Hydrochloric acid is used here in order to carry the discussion in the text as far as possible with this typical ionogen. If one takes care to make readings as described, the result is quite satisfactory, as is shown by the comparison of the ratios of the readings with the ratios calculated from the known conductivities of the various dilutions (see table below).