He also has a terrific collection of the chemical elements, portions of which are in his office at Wolfram in Champaign, IL. (I spent quite a while admiring the collection last year, and when I went to take a plane home, my luggage set off the TSA's chemical alarm.)
In his introduction to Polonium, Gray explains:
Polonium is a dangerous radioactive element that occurs only in minute quantities in nature. Before the invention of the audio CD quite a few people had a little bit of it in their homes in the anti-static brushes that were used to make LP records sound a bit less terrible.
Ah, the good old days!
Gray's site describes samples from his element collection:
For some crazy reason, in the 1950's Firestone made automotive sparkplugs containing radioactive polonium. Presumably the idea was that the ionizing radiation would allow the spark to travel more easily, making for better ignition. I think it's a fairly far-fetched idea.
. . . and Antistatic brushes. See also Jeremy Wagstaff, who explains why you don't want to eat your anti-static brush. But this is Theo Gray again. . .
These brushes, which you can still buy today (2002) are made for brushing static charge off of photographic negatives. The radiation from the polonium element (which must be replaced every year or so because the half life is only 138 days) ionizes the air around the brush, making it conductive and carrying away the static charge. . . .
This particular brush has an interesting history. Today (the date given below) I spent the afternoon at an old abandoned hospital complex tearing lead sheeting out of the former x-ray room (with, of course, the full permission of the owner, a developer who is going to demolish the building shortly). Ed Pegg, Jim, and I mined about 3/4 of a ton of lead in two and a half hours. It was hot, so we had to take breaks which consisted of wandering around this very large and quite eerie complex, bumping into things like stacks of old medical records and sharps containers with their contents of syringes and needles spilled out on the floor.
Near the CAT scan machine, which was still there, this brush was just lying on the table. I'd been intending to buy a new one exactly like it when I got around to it, but this is much better. Except for the fact that, as you can see in the picture, it is due to be replaced in 1984, and therefore has essentially no actual polonium left in it. That's the problem with these silly radioactives: They just keep evaporating on you.
Theo in his element.