What holds sugar and glows in the dark?

"Covered Uranium Glass Sugar Bowl, England, about 1840–1860. This glass was actually made with uranium, and has a deep yellow glow to it not found in any other kind of glass." -- Cabinet of Wonders

Apparently it's "not considered harmful," although it registers on a geiger counter and glows bright green under ultraviolet light.

Here's the dope on uranium glass from Everything2 --

Uranium Glass is exactly what the name suggests - it is glass, containing uranium dioxide  (uranium salts), and yes - it is radioactive.  A geiger counter will register a reading from Uranium Glass - however the level of radiation is only just above the level we are exposed to in everyday life, so is not considered harmful.

So just why did somebody decide to mix uranium dioxide with glass?

It's all about the colour. Uranium dioxide mixed into glass, results in a yellow-green coloured glass. It is generally accepted that it was first produced by Joseph Reidel, one of a long family line of glassmakers in Bohemia. In short, it contains approximately 2% uranium dioxide, producing its distinctive colour. While the colour may have been distinctive at the time uranium glass was first produced, it doesn't compare to the colours available using modern glass working techniques - however it is still prized by collectors worldwide. The reason for this is more than simply the curiosity value of owning an item containing uranium - rather, it is something that I am sure the creators of this glass could not have imagined.

Placed in a position with ultraviolet backlighting, Uranium Glass glows bright green. The difference is remarkable, the glass item going from being a yellowish-green - quite a muted and dirty looking colour - to a vivid, fluorescent colour. The electrons in the uranium are excited by the exposure to ultraviolet light, and enter a high energy state. In order to return to a low energy state, photons are released, resulting in the distinctive green glow of uranium glass. Collectors the world around meet to display their collections, shown under ultraviolet light.

Uranium glass is also known as 'Vaseline glass', however there are distinctions between uranium glass and vaseline glass.  Unfortunately, this distinction is by no means universal, and definitions vary.  What may be called uranium glass is Australia , may be called vaseline glass in the United States . Some glass produced with heat sensitive chemicals turn a milky white colour towards the edges - similar to the colour of vaseline - and this is referred to as vaseline glass in some places. Some collectors are members of organisations, who have stated the distinction between vaseline glass and uranium glass as far as their organisation is concerned - Vaseline Glass Collectors Inc. use two simple rules to define vaseline glass - it must be yellow first, and glow green under a ultraviolet backlight second. Obviously, this definition is quite different to the definition of vaseline glass as far as many other collectors are concerned. With so much disagreement amongst collectors and organisations, I'm not going to attempt to provide a definitive distinction - I doubt one will ever exist. For the sake of simplicity, I'm using the term uranium glass in this writeup.

The bulk of the uranium glass in existence today was produced from the 1830's to the 1940's. As uranium was a component of the atomic bomb, wartime governments were eager to restrict access to it. There were also concerns regarding the health of glassworkers exposed to uranium during the glassmaking process. In the 1950's, these restrictions were relaxed, however there are few places producing uranium glass to this day. In addition to the cost of uranium, health and safety regulations measures to protect workers against harmful exposure to radiation  have made the manufacturing process expensive.  These days, most uranium glass is sold by collectors.

There are several web sites displaying pictures of uranium glass, in its normal form, and as it appears under ultraviolet light.

Comments

[Hoodlumman]

So, is this glass jar dangerous? Was it not able to be handed down in the family because the Uranium made the family sterile or grow a second set of arms, etc?

[prairie biker]

too cool. there's a ton of it on ebay as well. lots of really neat stuff.

[iamnot]

I have a couple of camera lenses with similar qualities.

[Rob B.]

Ok... I want one

[gail]

Plenty available on e-Bay Rob

[Austin Mike]

Uranium glass is harmless. The radiation emitted consists of alpha particles, essentially about as powerful as an electron. These are stopped dead by a sheet of paper or a few inches of air. The glass may feel warm to the touch due to alpha emission, which is interesting.