Public Domain Mark
You can use this work for any purpose without restriction under copyright law. Read more about this licence.
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. Public Domain Mark. 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.