Radium (Ra) is an extremely radioactive metal (much more radioactive than an equal mass of uranium), producing all three kinds of ionizing radiation - alpha-, beta- and gamma-. It occurs naturally, as it is a result of the decay of uranium, and in turn decays into radon (Rn) - "a radioactive, colorless, odorless, tasteless noble gas" according to Wikipedia. Sounds fun, unless your house is built on granite bedrock (which contains uranium).
 Radium and radon quackery
Radium was first isolated in the beginning of the 20th century. About the same time it was found that the waters of several popular mineral springs were radioactive, as they contained "radium emanation" - a.k.a radon. The medical science of the time added two and two, forgot to subtract one thousand, and got four:
“”Radioactivity prevents insanity, rouses noble emotions, retards old age, and creates a splendid youthful joyous life.
|—Dr. C.G. Davis, the American Journal of Clinical Medicine|
As a result, an industry of radium and radon related products sprang up. People were not content bathing and drinking natural radioactive water at the springs and decided that they need to do it at home (radon decays relatively quickly so radon water can't be transported over long distances).
A sample breakdown:
- Various "radium emanators" and "radium jars" - water vessels for enriching water with radon. Some of them used porous ceramic containing radium or uranium, others were made of vaseline glass - normal glass coloured in a lovely yellow hue by adding uranium (exposed to UV light, it gives out an almost cartoonish radioactive green glow). Note that normal uranium glass is not very radioactive.
- Some smartass took the idea further and produced a soda syphon that used bulbs containing radon in addition to the carbon dioxide
- Radium tablets shouldn't be surprising by now, but what about radium suppositories?
- The crown of utmost radium idiocy goes to the guy who made a belt holding shiny capsules of radium-soaked paper under the wearer's testicles. He was an enthusiastic user of radium products. He died of bladder cancer.
Despite the "radiophobia" that gripped the West (and the East) after the bombing of Hiroshima and Nagasaki and the MAD days of the Cold War, radioactive "health" products, including radium and radon products, are still manufactured and marketed. If you want to bathe in radon-enriched water, some Japanese guys will sell you the Radon Egg - a ceramic container in which thorium tablets will release radon in your tub before the bath.
One of the reasons for the creation of the FDA was to crack down on radioactive quackery.
 Non-quack uses of radium
Radium was used in the first successful radiotherapy treatment for cancer, originated by Marie Curie whose death can be unmistakably attributed to radiation exposure itself. Thin metal cylinders filled with milligram amounts of radium salts, called "radium needles", were surgically implanted into cancer tissue and then removed after some time. This technique, called brachytherapy, is a legitimate medical procedure that is still used today. The radium salts, however, have largely been replaced by cheaper alternative isotopes, produced in nuclear reactors. It was at one time used to reduce the size of an overactive thyroid.
Other notable use of radium was in luminous paint used on watch hands, instrument dials, control panels and other equipment that had to remain usable in the dark without electricity. Due to radium's long half-life, cost and gamma emissions, it has been replaced in this role with promethium, and then tritium, which emit only low-energy beta particles and are therefore only dangerous when ingested. Today, almost no household glow-in-the-dark wristwatch dials or toys are made with radioactive substances at all; instead they rely on slow phosphorescence, the absorption and slow re-emission of ordinary light, which is why they typically only glow for a few minutes after you turn the lights out.