Need help identifying eyepiece from an old chemistry/science set
January 6, 2016 10:12 AM   Subscribe

I have a small black eyepiece from my dad's old chemistry set. Its purpose was to teach about isotopes by showing a visual example of radioactive decay. Any clues or knowledge of what the element inside is? Links to original documentation or similar sets? (Bonus question: This set is from the "our friend the atom" era, so, is it actually safe? I hope putting it up to my eye isn't like licking a radium covered paintbrush.)

What I do recall (though my memory may be fallible): It needs to be stored in the dark for like 24+ hrs to function - it doesn't work if it has been exposed to light. Your eyes need to be adapted to the dark to see the decay, which appears like a dancing green fuzzy image in the center of the eyepiece.

The eyepiece itself looks like this, but with a lens only at the wide end. The narrow end is closed off.

When you look into it with dark adapted eyes, what you see looks like this. (Only dancing around, very dynamic.)
posted by BleachBypass to Science & Nature (6 answers total) 3 users marked this as a favorite
Best answer: That sounds like a spinthariscope. That article provides a really excellent history of the device and talks about the elements most likely found within (nowadays, thorium and americium).
posted by barchan at 10:24 AM on January 6, 2016 [1 favorite]

Best answer: Sounds like a Spinthariscope
posted by Captain_Science at 10:25 AM on January 6, 2016

Response by poster: Yes!!! Thank you!
posted by BleachBypass at 10:46 AM on January 6, 2016

If it's from an old chem kit, it's probably radium bromide, which emits ionizing radiation in tiny amounts. Ionizing radiation is not good for you, but the amounts here are so small that you get far more daily from direct sunlight, standing near large amounts of granite, or eating bananas. Don't sweat the dosage; we evolved to handle far greater levels than this.
posted by Sunburnt at 11:10 AM on January 6, 2016

Most of the radiation from americium, thorium, and/or radium is alpha, and external alpha isn't dangerous. The glass of the eyepiece is more than enough to stop all alpha radiation.

Where beta and gamma require inches of lead or feet of concrete for adequate protection, a piece of paper is all you need to stop alpha. In fact you don't even need that; the layer of dead cells on top of your skin is enough to protect you.
posted by Chocolate Pickle at 12:19 PM on January 6, 2016

That is an excellent little article, barchan, and the blog it's part of is outstanding.

I've read I don't know how many accounts of the discovery of radioactivity, and I learned tons from that piece.
posted by jamjam at 2:46 PM on January 6, 2016 [1 favorite]

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