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Message: <blockquote data-quote="TANSTAAFL" data-source="post: 3915670" data-attributes="member: 27098"><p>Glad to hear that. I have a few old radium dialed instruments as check sources and collectibles. I have an old aircraft oxygen air pressure gauge that the glass comes of of easily, counts went from 10K per minute to 60K per minute (with an alpha, beta and gamma sensitive geiger counter, a Monitor 4 Digalert.) Radium is a very interesting element btw, actually emits gamma, beta and alpha particles. Way back in the 1920's chemists at watch companies knew which proportions of radium 226 and 228 worked best for the best luminescence along with zinc, chlorine and  sulfur compounds. Radium paint formulas were kept very secret. I have a few radium dialed items that still glow dimly to this day that date back from the 1920's. Here is an interesting experiment. Take an old watch into a darkened room along with a good magnifying lens, let your eyes adjust to the dark and view the hands or numbers under the lens. You will still see scintillations decades later. There used to be devices sold in the early 1900's called spinthariscopes that were pocket sized and you could sit and watch the scintillations. Spinthariscopes are still sold today.</p></blockquote><p></p>