THERE are over thirty elements which are radioactive , and while the existence of some of them is a matter of only a few seconds, or even the cycle of a second, they are to be regarded in the same light as iron, copper, or calcium, having all the properties of other elements, in regard to atomic weight, capacity for heat, specific gravity, and existing in such forms as solids, liquids, or gases. The majority of these elements X_X 1 RADIUM G s^-~\ (PROBABLY (208.4J LEAD) > ' Disintegration series of uranium, radium, thorium, and actinium. URANIUM 23 radioactive but very feebly, and at present it is only an interesting physical fact. But it is for the future to develop, and no doubt in time our common potash may be a peer of radium, or perhaps analogous to uranium at the head of the disintegration series. URANIUM. Uranium. Atomic weight, 236.7. Specific gravity, 18.6. Period of average life about 8,000,000,000 years. Found in nature as black oxide, pitchblend; also as uranates in combination with calcium, and often associated with mica ores, clevite, the hydrated oxide, and in carnotite where it is combined with vanadium. Other rocks contain it as gummite, autunite, samarskite, and many other forms. It is widely disseminated throughout the world's crust, but only found in workable quantities in Hungary, Bohemia, and in the United States in a few widely separated places. Chemically it forms two combinations with oxygen, UrO2, and UrOa; forming two classes of salts, the uranic and uranous.
