In 1924 a pitchblende deposit, very rich in radium, was discovered in Ferghana, in Russian Turkestan. Soviet Russia is now mining the ore and extracting the radium, which is kept at the Radium Institute of the Academy of Science.
Curiously enough, more than $500,000 worth of radium has been added to the world’s store of this valuable element by “boiling down” British cannons used in the World War. No fewer than five grams—less than a tablespoonful—have been secured by British scientists by this process. The radium is stored in a lead safe weighing almost two tons—a container which was invented by a Dr. Kuss, and the composition of which is known only to himself. One of the greatest difficulties of scientists has been to find some material which would prevent the constant bombardment of the radium rays.
One important result of these recent discoveries—especially that of the Congo deposits—is that the price of radium dropped $30,000 a gram, and sells now at the rate of $70,000 a gram instead of some $100,000. The Standard Chemical Company of Denver, Colorado, has been obliged to close down its three-story laboratory, which until the close of the year 1922 had, for several years previously, been producing a million dollars’ worth of radium annually. The Paradox Valley carnotite ore cannot be worked in competition with the rich deposits of the Belgian Congo. It has been stated that five pounds annually could be produced from these Congo deposits. The Colorado company had been selling at the rate of $58,500,000 a pound. The Congo company can profitably sell the precious element at $29,250,000 less a pound.
So, unless war breaks out again to prevent shipments from abroad, the United States of America will produce no more radium for a long while to come.
THE RADIOACTIVE DISINTEGRATION SERIES
In order to show the decomposition products of the two parent radioactive elements—Uranium and Thorium—and their chief characteristics, together with their relations to one another, and the time required for the product (element) to be half transformed, it is customary to arrange them in a disintegration series. There are three series, Uranium I, Uranium Y, and Thorium.
In the first table given below is shown how the series known as Uranium I is transformed into the end-product, uranium lead. This is followed by the Uranium Y (or Actinium) series, and by the Thorium series; the end-product of all three being a characteristic type of lead. In the tables T is the “time-period” of a product, or the time required for the product to be half transformed. In the column “Rays” is shown what type of ray, or rays, is, or are, emitted during the disintegration process—A=Alpha rays (or particles), B=Beta rays (negative electrons), and G=Gamma rays (or X-rays of very high “frequency”).
“In the great majority of cases,” says Sir Ernest Rutherford, “each of the radioactive elements breaks up in a definite way, giving rise to one Alpha or Beta particle and to one atom of the new product. Undoubted evidence, however, has been obtained that in a few cases the atoms break up in two or more distinct ways, giving rise to two or more products characterized by different radioactive properties. A branching of the uranium series was early demanded in order to account for the origin of Actinium.”
In the first column is given the “atomic weight” of each radioactive element, the weight decreasing with (almost) every “disintegration period.” The figures followed by an interrogation point are Rutherford’s, and indicate that slightly different figures are given by other authorities.