This article is available on the internet from the Online Glass Museum, New Zealand at: www.glass.co.nz/uranium.htm - It explains how uranium oxide, when added to glass, produces colours varying from amber through yellow, to green, depending on the composition. Uranium glass is radioactive; apply a geigercounter and you get a positive reading. It is also fluorescent - get an ultra-violet torch and shine it on the glass in the dark and the object will glow beautifully. These radioactivity levels are considered to be harmless as tests conducted by Jay Glickman (author of "Yellow-Green Vaseline: Guide to the Magic Glass") show that the radiation from even large quantities of the glass at close quarters is as harmless as radiation from a tv set or microwave oven. The paper also goes on to describe how it was invented by Josef Reidel in 1830.
