RADIUM AND RADIANT ENERGY.

Abstract

The discovery of radium is of universal interest. There is scarcely a science that has not been affected by it. But it can be of no greater interest to any one than to physicians, because of its therapeutic possibilities. The termination "um" indicates that radium has been added to the family of elements. A substance to be admitted into the list of elements must have the following qualification: It must have a spark spectrum of its own. This spark spectrum must be measured and be different from all other forms of known matter. Radium fulfills this requirement. Demarcay has shown that radium has a spark spectrum of fi um fifteen lines, with no lines belonging to any other element. The discovery of radium during the closing years of the nineteenth century was one of the most wonderful achievements of that century, from a scientific point of view. In some ways it amounts