Gas electrode for general use / by G.S. Walpole.

  • Walpole, George Stanley.
Date:
[1913]
Catalogue details

Licence: In copyright

Credit: Gas electrode for general use / by G.S. Walpole. 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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    XLI. GAS-ELECTRODE FOR GENERAL USE. By GEORGE STANLEY WALPOLE. From the Wellcome Physiological Research Laboratories, Herne Hill, S.E (Received June 11th, 1913.) The standard forms of hydrogen-electrode, such as those used by Dolezalek [1899], Wilsmore [1900] and Bjerrum [1910] and, for fluids containing carbon dioxide, Hasselbalch [1910], must remain indispensable when physical measurements of the highest order of accuracy are under- taken. With these, after the expenditure of considerable time and care, and with continued vigilance over every part of the electrical apparatus, con- secutive results concordant to about 0-05 millivolt can sometimes be obtained. But, for these results to have any meaning beyond the nearest millivolt or two, it is essential that the diffusion potential difference of the cell should be accurately known in every determination: and as this is recognised, by Cumming and others whose investigations continue to throw light on this difficult subject, to be almost impossible, it follows that, as far as absolute H' ion determinations are concerned, attention should be focussed more particularly on diffusion potential errors (in view of their greater magnitude) than on those found at the electrode itself. In general laboratory practice, therefore, especially* when dealing with protein-containing materials, which may or may not be free from carbon dioxide, the most suitable electrode is not one which, when coupled with an ideal electrical apparatus, will give results of this high order of accuracy, regardless of the expenditure of time and material. Rather it is one which, without exaggerating appreciably the diffusion potential error, will give, under ordinaiy working conditions and in a few minutes, results correct to 1 millivolt or so on one or two cc. of fluid without loss or contamination. Anticipating a long series of H' ion determinations on protein solutions, some of them containing carbon dioxide, I endeavoured to devise such an electrode. The arrangement subsequently adopted and the experiments made to discover its imperfections are described below. Only one form of