Selenium : its electrical qualities, and the effect of light thereon : being a paper read before the Society of Telegraph Engineers, 28th November, 1877 / by Willoughby Smith.

  • Smith, Willoughby, 1828-1891.
Date:
[1877]
Catalogue details

Licence: Public Domain Mark

Credit: Selenium : its electrical qualities, and the effect of light thereon : being a paper read before the Society of Telegraph Engineers, 28th November, 1877 / by Willoughby Smith. 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.

    11/28 (page 9)
    Mark. Megohms. Megohms. • 554 o 70 79 F • Z OiiJ. 0 CO* c •? vjr . 045 5 77 4^ H I Ci'fift I r\. . . 53'32 23 13 T i-< . . • 730 3 t A t * ^ M iVi • « 5392 15 53 N . ' . /I T • T n T 1 'OO () 1 54 0 •+9 4 p 24 24 Q • •13258 •097 R . •003157 •003 A . . 3147 59*25 During- the time occupied by the test while light was ' excluded, the temperature imperceptibly decreased from ; 44*5° to 43'8°. The resistance of bar A remained the : same throughout the test. During the time occupied by the test in which the light was admitted, the tem- ; perature fell from 43*7° to 43 2, so that during the j: whole time occupied by the tests, which was ninety-five !■ minutes, the temperature only varied i3°. The apparent r dull solar light had a much greater effect on the re- [; sistance of the bars than the apparent bright artificial j; light from coal gas. '< The above test was repeated at noon on a hot ij midsummer day, with a clear atmosphere and the rays ii of the sun falling direct on to the box. While light was ii excluded, the temperature remained at 108° Fahr., and the resistance of the bar marked A remained constant throughout the test, which occupied twenty minutes. During the test with the light admitted, the temperature increased from 112*5° to 121°, and the resistance of the bar A decreased. The intercepting of the light by the