200 NEW YORK STATE MUSEUM 



Sometimes uranium minerals, even when comparatively pure, are 

 found to be lacking in the amount of radium required for equilibrium. 

 Some authorities believe this to be due to a natural leaching of the 

 radium from the uranium; while others believe that such vast 

 periods of time are required for the original establishment of equi- 

 librium, estimated in the millions of years, that the minerals which 

 show a deficiency in radium have not existed for a sufficiently long 

 time to have yet acquired equilibrium, and that only the older 

 uranium minerals have existed long enough for this purpose. 



These great spaces of time required for the formation of radium 

 from uranium would, of course, render it impracticable, from a 

 commercial standpoint, to keep uranium, from which radium has 

 been artificially extracted, until the latter has been restored. 



The production of radium from uranium is usually stated in mil- 

 ligrams 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 state, but only in 

 the form of its salts. A few years ago these salts were supposed 

 to have a generally 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, com- 

 passes and other instruments; and this use has so greatly increased 



