Radium, and other radio-active substances : polonium, actinium, and thorium. With a consideration of phosphorescent and fluorescent substances, the properties and applications of selenium, and the treatment of disease by the ultra-violet light / by William J. Hammer.

  • Hammer, William Joseph, 1858-1934.
Date:
1903
Catalogue details

Licence: In copyright

Credit: Radium, and other radio-active substances : polonium, actinium, and thorium. With a consideration of phosphorescent and fluorescent substances, the properties and applications of selenium, and the treatment of disease by the ultra-violet light / by William J. Hammer. Source: Wellcome Collection.

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    board produce a most beautiful effect when light screened by dark blue or violet glass is thrown upon them. Sodium vapor fluoresces brilliantly in sunlight. I also have here samples of tungstate of calcium, platino- barium cyanide, sulphide of zinc, and similar preparations which have been extensively used in the fluorescent screens for X-ray work. Here is a specimen of Willemite which when exposed to the ultra-violet light produced by the bright snappy condenser spark between these iron electrodes shows a magnificent fluorescence. Here is a card with words written with a solution of platino- barium cyanide which fluoresces beautifully when exposed to the ultra-violet light of the iron arc, especially when shielded by the accompanying colored glass plates. I have also one of Prof. R. W. Wood’s interesting ultra-violet screens, consisting of four plates of cobalt glass between which are gelatine films containing nitroso-dimethyl-aniline with cop- per oxide, which screen when employed in front of the arc lamp renders beautifully fluorescent a lump of uranium nitrate held in the focus of the invisible rays. Through the courtesy of Dr. Von Recklinghausen, I am enabled to show you a Cooper-Hewitt tube which is enclosed in a screen soaked in rhodamin, the best substance which thus far has been found which is fluorescent in the light of the mercury arc. It is well known that many bodies become red hot at a tem- perature of between four and five hundred degrees Centigrade, and to make them white hot a temperature of between eight hundred and a thousand degrees is necessary; but there are many substances which are phosphorescent and which possess the property of giving off considerable light without sensible heat. I have here some samples of two phosphorescent substances which have been known for many years—one of them a sulphide of barium or Bolonese phosphorus, and the other a sulphide of calcium or Canton’s phosphorus. The former was discovered in 1602 by Casciarlo, a shoemaker in the city of Bologna who prepared it by the partial calcination of a certain powdered heavy spar mixed with a little flour meal, which he roasted in the furnace; and found afterwards that when exposed to sunlight it would shine in the dark. This preparation was succeeded by the discovery of John Canton, who calcined oyster shells with charcoal and meal in a closed crucible, thus producing a brilliant phosphorescent substance called after his name.