=Production.=--The United States is today by far the largest producer of radium and uranium ores in the world, and is also the largest producer of manufactured radium and uranium compounds. Before the war, England, France and Germany, especially Germany, imported large quantities of American ores and extracted the radium in a refined state as its different salts, much of which was returned to the United States for sale. Now, however, American ores are almost entirely treated in the United States, with the exception of a little shipped to England and possibly to France. The Standard Chemical Co., of Pittsburgh, was a pioneer in this work, and others quickly followed, among them the National Radium Institute, of Denver; the Schlesinger Radium Co., of Denver; the Chemical Products Co., of Denver; the Cummings Chemical Co., of Lansdowne, Pa.; the Radium Luminous Materials Corporation, of New York, and others. Before the discovery of radium in 1898, but little attention was given to uranium ores in America, though some little pitchblende was shipped from the Central City, Colorado, region for use in making uranium compounds. Shortly after the discovery of radium, however, mining was begun on the carnotite of southwestern Colorado, and from 1900 to 1910 several companies were formed to work these ores both in Colorado and Utah. The pitchblende of Central City also began to attract renewed attention. For a few years active work was done in prospecting for it, but the quantities have so far proved to be small. A few tons probably represent the total amount derived from these mines since the search began. In the meantime, however, the production of carnotite increased rapidly until 1915, when it greatly decreased on account of the curtailment of shipments to Europe. In the latter part of 1916, however, the production increased again, on account of the increased consumption of ore in this country, and in 1918 the production was very active, largely on account of the increased use of radium not only in medicine but especially in luminous paints. The amount of radium and uranium ores produced in the United States, or in fact anywhere, during a given period, is difficult to determine, on account of the different bases on which reports are made, but it may be said that the tonnage is small compared with that of ores of commoner metals, a few thousand tons being a large amount of carnotite, and simply a few tons or pounds being a large amount of pitchblende. Though the mining of radium and uranium ores in the United States began about 1900 or shortly before, no very large quantities were produced until 1912, when about 1,100 tons were mined, consisting chiefly of Colorado carnotite. The production gradually increased to several thousand tons yearly, practically all of which is carnotite from Colorado and Utah. RADIUM AND URANIUM RESOURCES OF EUROPE