Paper, 'On radiant matter spectroscopy:—Examination of the residual glow' by William Crookes

Description

Crookes writes: 'The duration of phosphorescence after cessation of the exciting cause is known to vary within wide limits of time, from several hours in the case of the phosphorescent sulphides to a minute fraction of a second with uranium glass and sulphate of quinine. In my examinations of the phosphorescent earths glowing under the excitement of the induction discharge in vacuo, I have found very great differences in the duration of the residual glow. Some earths continue to phosphoresce for an hour or more after the current is turned off, while others cease to give out the light the moment the current stops. Having succeeded in splitting up yttria into several simpler forms of matter differing in basic power, and always seeking for further evidence of the separate identity of these bodies, I noticed occasionally that the residual glow was of a somewhat different colour to that it exhibited while the current was passing, and also that the spectrum of this residual glow seemed to show, as far as the faint light enabled me to make out, that some of the lines were missing. This pointed to another difference between the yttrium components, and with a view to examine the question more closely I devised an instrument similar to Becquerel’s phosphoroscope, but acting electrically instead of by means of direct light.'

Annotations in pencil and ink throughout. Includes two diagrams of experimental apparatus and a spectrum diagram.

Subject: Spectroscopy

Received 10 February 1887. Read 17 February 1887.

A version of this paper was published in volume 42 of the Proceedings of the Royal Society as 'On radiant matter spectroscopy:—Examination of the residual glow'.

Reference number

PP/10/13

Earliest possible date

1887

Physical description

Ink and graphite pencil on paper

Page extent

11 pages

Format

Printed
Diagram