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.

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    resistance of the coils of which was 6,200 ohms. The box had been closed for three hours previous to the commencement of the test. Table 2 gives the resistance of each bar in megohms. The black figures show the resistance while light was excluded, and the red figures the resistance when light was admitted. The same arrangement will apply to all the tables to which I shall have to refer. No. 2. Maik Megohms. Megohms. A . . 303-6 2II-4 B . . 4-385 4-172 C . . 229-3 163- D . . 46-43 3444 E . . 591-3 370- F . 281* 197-3 G . . 667- - 361*5 H . 27-86 21-62 I . . 31-05 26*16 K . . 52-33 41- L . 739-9 535-1 M . . 61-10 42-09 N . . 47-83 34-31 O . . 150-3 ii9*9 P . . 19-17 17-54 Q . . 00099 o'oo82 R . . 0002919 0*002923 A . . 303-6 199-8 Each reading was taken after the current had been on one minute, commencing with the bar marked A and proceeding consecutively to the one marked R. During the test with the light excluded, the temper- ature increased from 61° to 63° Fahr. ; but this appears not to have interfered with the values, as, on the com- pletion of the test, the bar marked A was re-tested, and