In normal circumstances, this glass, lion-shaped ornament may appear fairly unremarkable. But put it under a UV light, and what previously seemed like an innocuous paperweight begins to give off an eerie, green glow.
The lion’s curious luminescence is actually due to small quantities of the radioactive element uranium, which was added to the glass during production.
Produced by James Derbyshire and Sons, a Manchester firm in 1874, the lion came to Leeds in a number of pieces for conservators at the Leeds Discovery Centre to restore.
Using a Geiger counter, they detected trace amounts of radiation, confirming its invisible additional ingredient, before carefully photographing it under UV light.
In the early 19th Century, uranium was deliberately added to some glassware to give it a green or yellow tinge, which used to be described as “Vaseline glass.”
Whilst iron can be used to give glass a similar colour, adding uranium also made ornaments fluorescent , meaning they would stand out more in the early evening light of a traditional Victorian home that would have been far less well lit than a modern house.
Uranium continued to be added right through to before the Second World War.
Councillor Brian Selby, Leeds City Council’s lead member for museums and galleries, said: “What’s so fascinating about this particular object it that, under normal circumstances, the thing that makes it so special and unusual is completely invisible.”
“Like many of the items in our collection, there’s more than meets the eye and it’s only when you delve into the story behind the object that its true nature becomes apparent.”