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Spottiswoode and Moulton write: 'In the preparation of tubes for our experiments it was often noticed that, after the exhaustion had been carried to a certain degree, the passage of a strong current had the effect of increasing the pressure. This appeared to be due to an expulsion of gas from the terminals themselves by the passage of the discharge. And accordingly the use of such currents from time to time during the process of exhaustion was adopted for making the vacuum more perfect and more permanent than otherwise would have been the case. On the other hand, it was also noticed, that after the tube had been taken off the pump and sealed in the usual way, the passage of a strong current had in some instances the effect of decreasing the pressure. We thus met with two effects, apparently due to the same cause, but diametrically opposite in character. The fact of the tube being on the pump or off it did not appear to be at all material to the question, because the first effect could be obtained when the tube was temporarily shut off by a stopcock. Nor indeed did either the first or the second effect depend upon the absolute pressure, although neither was observed except when the pressure was such as to approach the stage when Crookes’ phosphorescence was produced.'

Annotations in pencil and ink throughout.

Subject: Chemistry / Physics

Received 25 March 1882. Read 30 March 1882.

A version of this paper was published in volume 33 of the Proceedings of the Royal Society as 'On the movement of gas in "vacuum discharges"'.

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Ink and graphite pencil on paper
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4 pages

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William Spottiswoode

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John Fletcher Moulton

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William Spottiswoode, John Fletcher Moulton, Paper, 'On the movement of gas in "vacuum discharges"' by William Spottiswoode and J [John] Fletcher Moulton, 1882, PP/1/40, The Royal Society Archives, London,, accessed on 23 May 2024

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  • Proceedings Papers

    Dates: 1882 - 1894

    The archival collection known as 'Proceedings Papers' is comprised of manuscripts and occasional proofs of scientific papers sent to the Royal Society which were read before meetings of Fellows and printed in full in the Proceedings of the Royal Society.

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