A large pear-shaped glass bulb is attached vertically to a turned wooden base. There is a tall glass arm or stand inside of the glass bulb which holds a large pink mineral with a blue underside. Nearer the bottom of the bulb is a perpendicular glass tube with an electrode inside it. At the top of the inside of the glass bulb is another electrode with a metal disk attached via a short metal rod.
Accession Number: 2009.ph.244
Alternative Name: Crookes Tube with one mineral
Primary Materials: Wood, Metal, Glass
Markings: Old inventory number = phy79.
Dimensions (cm): Height = 40.5, Diameter = 15.5
Minerals fluoresce under bombardment of cathode rays. Possibly used for spectroscopy.
Date of Manufacture:
In October 1898, instructor and future professor J.C. McLennan visited the Geissler Establishment, in Bonn, Germany. The Geisslers were famous for the manufacture of Crookes Tubes. McLennan reported in a letter back to Professor James Loudon that he had purchased some of these for the Toronto physics laboratory, including at least one with a “phosphorescent mineral”, which, he reported, “gives the most beautiful effect that I have seen.” (McLennan, 1898)
There are numerous examples of phosphorescent mineral tubes in the collection. It is possible that one, or more, of these were purchased by McLennan during his 1898 trip to Bonn.
Letter from J.C. McLennan to J. Loudon, October 10, 1898. University of Toronto Archives B1972-0031 Box 004 File 43