Potash (or potassium) is an alkaline metal. Chlorides, sulphates, etc., are found in Germany. Wood ashes and sugar beet refuse furnish much of the world’s potash. Stassfurt, Germany, possesses the only known large deposit of natural potash salts. These salts are the source of potash in many chemical industries and in fertilizers. It is exported in large amount from Germany to England, France and America.
Quartz (silica) is of many varieties, crystalline to amorphous.
Rock flint is mined in Connecticut and Pennsylvania, and also comes from the chalk cliffs of England and France.
Sandstones are quarried and used for building in almost all parts of the world. Pennsylvania, Ohio, and New York supply the greatest quantities in the United States. Honestones and whetstones are mostly sandstone, and in this country are largely quarried in Arkansas, Michigan and New Hampshire.
Rock crystal is employed for lenses. Many semiprecious stones are varieties of quartz, as agate, moss agate, onyx, sard, chalcedony, chrysoprase, jasper, etc.
Rock flint and quartz sand are used in making glass and pottery.
Outside of building stones, quartz is used in greatest amount in making glass and pottery. For glass it is melted with alkali (soda ash) and either lime or lead oxide. Glass is either blown or molded. Belgium, Austria, Germany, France, Great Britain and the United States manufacture glassware. Pennsylvania, Indiana and New Jersey are the leading states.
Radium is the most characteristic of those substances which possess the property of radio-activity—i.e. have the power of producing photographic or electric effects by a process identical with or analogous to radiation. The property was first observed in uranium by Becquerel in 1896—hence the name “Becquerel rays.” In 1898 Schmidt and Madame Curie discovered almost simultaneously that the compounds of thorium had the same radio-active property; and further elaborate investigations led to the discovery of polonium, radium, and actinium, as new substances with radio-active properties. Polonium was the name given by M. and Mme. Curie to the radio-active component of bismuth separated from pitchblende. Its activity is transient. In the new field of research thus opened up important work has been done by Rutherford, Crooks, Ramsay, Soddy, Huggins, and others.
Radium is derived from pitchblende, in which it exists in very small quantities. After a long-continued process of fractional crystallization it has been prepared in the form of a tolerably pure salt. The process of obtaining the element is very tedious. One to two kilograms of impure radium bromide can be procured from a ton of pitchblende residue only after processes extending over months. For the remarkable chemical properties of radium, see further under [Radio-activity].