An application to electrolytes of the hydrate theory of solutions / by T. Martin Lowry.

  • Lowry, T. Martin (Thomas Martin), 1874-1936.
Date:
[1905]
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Licence: In copyright

Credit: An application to electrolytes of the hydrate theory of solutions / by T. Martin Lowry. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    UNCORRECTED PR This paper may been read before the 6of.—ptmte, f4r^em^ers only. Xi ^ -, . ... , ndTra%e*'' published Faraday Society. until it has The Council invites members unable to be present at the reading of the Paper, to send their contributions to the discussion in writing to the Secretary, so that they may be communicated to the meeting. AN APPLICATION TO ELECTROLYTES OF THE HYDRATE THEORY OF SOLUTIONS. ByT. MARTIN LOWRY, D.Sc. (A Paper to be read before the Faraday Society, Thursday, May 18, 1905. During a period of nearly twenty years two rival theories have existed as to the nature of solutions, and especially of those solutions which are capable of conveying an electrical current by electrolysis. According to the hydrate theory, as developed by Mendeleef and by Pickering, the chief result of adding water to a salt is to produce a series of hydrates increasing in complexity with the amount of water added. Arrhenius, on the other hand, has suggested that the main resulfr of the interaction is not the association of solvent and solute, but the dissociation of the solute into the ions into which it is resolved by electrolysis. The object of the present communication is to consider the possibility of extending the hydrate theory to electrolytes in such a way as to take account of the observations which form the experi- mental basis of the theory of electrolytic dissociation. The hydrate theory postulates that an aqueous salt solution consists of a mixture of hydrates in equilibrium with the solvent and with one another. By crystallising under various conditions a limited number of these hydrates can be separated, but the solution probably contains many hydrates which cannot be isolated in this way. Amongst the hydrates that can exist only in solution there are probably included many compounds of greater complexity than those which separate when crystallisation takes place. But it must be supposed that even in solution there is a limit to the possibility of hydrate formation, so that ultimately a stage will be reached at which the molecule as such will be unable to combine with any further quantity of water. According to the view now under consideration the ionisation of an aqueous electrolyte consists essentially in a further process of hydration whereby the fully hydrated molecule combines with an additional quantity of water to form two or more hydrated ions. The process of ionisation might thus be compared with the biological process of karyokinesis whereby the growth of a cell leads ultimately to the fusion of the individual and its resolution into two or more separated cells. The possibility that the ions may be hydrated has frequently been dis- cussed,but this has usually been regarded as a secondary phenomenon, and * See especially Kohlrausch, Sits. ber. Preuss. Akad. Wiss., Berlin, 1902, 26, 579 ; Walden, Zcit. phys. Client., 1902, 39, 539, where a large number of references are given, and a monograph, Von der Hydraten in -wasseriger Lbsitng, Ahren’s