SUMMARY
Molybdenum commands attention because of its growing importance as a steel alloy metal. Although the metallurgy and properties of molybdenum steels are not thoroughly understood and their use is not widespread, especially in this country, accumulating evidence indicates that molybdenum will eventually become one of the common alloy metals. It is used in the form of wire as supports for incandescent light filaments and in electrical apparatus, and may become essential in the manufacture of special steels. It cannot be easily replaced in chemistry, and for its other applications it is better and cheaper than other materials.
Up to 1915 practically all of the molybdenum produced came from Queensland, New South Wales, and Norway. At present more important deposits are being developed in Ontario, Quebec, and British Columbia, Canada, and in Colorado, Arizona, New Mexico, and other western states. The mineral is widely distributed and the discovery of additional deposits is likely if the demand is sufficient to encourage prospecting. The United States has deposits large enough to meet all domestic needs and also to produce a surplus for export. Some molybdenum is obtained from Mexico, Peru, and Spain, but the United States, Great Britain (Canada and Australia), and Norway control the important deposits.
The largest molybdenum deposit in the United States, located at Climax, Colorado, is owned by the Climax Molybdenum Co., a subsidiary of the American Metal Co. (formerly German), and by the Molybdenum Products Co., of Denver, an American company. Other deposits in Colorado are owned by the Primos Chemical Co., a company that had strong German connections before the war, but has been taken over by the Vanadium Products Corporation, an American company. Other producing deposits of the United States are owned by American citizens.
The Knaben mines, the most important in Norway, have been owned since 1905 by an English company, but, according to a report, they have been acquired by a Norwegian company. A number of the deposits of northern Mexico are owned by Americans. Others are owned by the Madero estate (Mexican). The Canadian and Australian deposits are controlled by small, independent operators. Both the United States and Great Britain have ample supplies of molybdenum; France produces none and is dependent upon other countries; Germany, which was much interested in molybdenum before the war, probably has no large stocks on hand.
CHAPTER XI
RADIUM AND URANIUM
By R. A. F. Penrose, Jr.
Radium is a metal and is a product of the disintegration in nature of the metal uranium. Both radium and uranium are elements. Radium has been isolated in its metallic state, but is not used in that form and is known better in the form of its salts, among the most important of which, so far as their uses are concerned, are the bromide, chloride and sulphate.
Wherever uranium occurs in nature, radium is associated with it in certain definable quantities. Uranium can contain, however, only a certain maximum amount of radium at a time, and when it has reached this stage, the radium and uranium ratio is said to be in equilibrium. In this condition the amount of radium per gram of uranium has been calculated by Rutherford to be 3.4 × 10⁻⁷ gram. This corresponds to 1 gram of radium element to about 3,000 kilograms of uranium element, or 1 part of radium element to about 3,000,000 parts of uranium element. Uranium minerals as mined are usually impure and carry only a small percentage of uranium elements, so that the ratio between radium and the crude uranium ore may be 1 to several or many times 3,000,000.
The production of radium from uranium is usually stated in milligrams or grams, and even in the richest ores there is usually only a small fraction of a gram to a ton, while in the ordinary lower-grade ore there are only a few milligrams to a ton, corresponding to a small fraction of a grain to a ton. Less than twenty years ago it was estimated that probably not one gram of radium element in the form of its refined salts had been extracted in the world. Today a great many times, perhaps a hundred times or more, this amount has been extracted and is in use. The annual production of radium today in the world is probably several grams. The annual production of uranium in the world is probably several hundred pounds.
The unique position of uranium as the source of radium in nature makes it necessary to discuss both materials together.
Uses of Radium.
—Radium is a heavy white metal which is very unstable, and alters rapidly in the air. It is not used in its metallic stage but only in the form of its salts. A few years ago these salts were supposed to have a general beneficial effect in the treatment of cancer and other malignant growths, but more recent investigations seem to confine their influence to only certain forms of these afflictions. Their influence in other diseased conditions is often very marked, but the full extent of the field of usefulness of radium for medical purposes has not yet been very clearly defined.
In recent years radium has been applied to other important purposes, especially in luminous paint for watches, clocks, compasses and other instruments; and this use has so greatly increased in recent years, especially for military purposes, that it now consumes more radium than is used in medicine. Radium salts are more or less luminous when seen in a darkened room, and this quality is often increased by the admixture of certain other materials, notably zinc sulphide. Hence their value in luminous paints. Radium salts also cause certain minerals to fluoresce, notably the zinc minerals willemite and sphalerite. In Germany, where radium during the war became scarce on account of the shortage of the ores from which it is extracted, radium salts are said to have been preserved for medical purposes, and mesothorium and other radioactive substances used in making luminous paints.
Uses of Uranium.
—Uranium is a heavy white metal, which slowly tarnishes on exposure to the air. The chief use of uranium today is as a source of radium. For many years before the discovery of radium, however, uranium compounds were used in a small way in coloring glass and porcelain, in photography, in reagents for chemical analysis, in mordants for dyeing and for other minor purposes. The use of uranium metal in small quantities in steel manufacture has been tried with some degree of success.