Read "The Wonders of Radium" by Maynard Shipley online for free on Textopian. Full text with search, annotations, highlights, and AI-powered reading aids.
During the World War large quantities of radium were employed by the Allies for night compasses, luminous dials on airplanes, gun-sights, etc. In times of peace it is used on pendants for locating electric lights and switches in the dark, key-holes, fire-extinguishers, poison bottles, emergency call-bells, and in many other ways. For example, some mining corporations use signs in their mines made luminous in the dark by phosphorescent paint made from radioactive substances. These luminous signs are not affected by atmospheric conditions.
Yet for all these uses, including "radium watches" and clocks, not more than half an ounce of radium has been used since its discovery in 1898. A few millionth parts of a gram of radium, in the form of radioactive barium sulphate, a large portion of phosphorescent zinc sulphide (crystallized zinc), mixed with varnish and some adhesive substance, give enough material to illuminate 40 or 50 watches. One gram of radium ( = 16 grains) combined with 20,000 grams of secret process phosphorescent zinc sulphide is sufficient to make 667,000 watches luminous for many years. The factories of this country are now turning out about four million radium watches annually.