It is remarkable that we owe the discovery of this wonderful element to a woman, Mme. Sklodowska Curie, the wife of a French professor and physicist. Mme. Curie began her work in 1897 with a systematic study of several minerals containing uranium and thorium and soon discovered the remarkable fact that there was some agent present more strongly radio-active than the metal uranium itself. She set herself the task of finding out this agent and in conjunction with her husband, Professor Pierre Curie, made many tests and experiments. Finally in the ore of pitchblende they found not only one but three substances highly radio-active. Pitchblende or uraninite is an intensely black mineral of a specific gravity of 9.5 and is found in commercial quantities in Bohemia, Cornwall in England and some other localities. It contains lead sulphide, lime silica, and other bodies. To the radio-active substance which accompanied the bismuth extracted from pitchblende the Curies gave the name _Polonium_. To that which accompanied barium taken from the same ore they called _Radium_ and to the substance which was found among the rare earths of the pitchblende Debierne gave the name _Actinium_. None of these elements have been isolated, that is to say, separated in a pure state from the accompanying ore. Therefore, _pure radium_ is a misnomer, though we often hear the term used. [Footnote: Since the above was written Madame Curie has announced to the Paris Academy of Sciences that she has succeeded in obtaining pure radium. In conjunction with Professor Debierne she treated a decegramme of bromide of radium by electrolytic process, getting an amalgam from which was extracted the metallic radium by distillation.] All that has been obtained is some one of its simpler salts or compounds and until recently even these had not been prepared in pure form. The commonest form of the element, which in itself is very far from common, is what is known to chemistry as chloride of radium which is a combination of chlorin and radium. This is a grayish white powder, somewhat like ordinary coarse table salt. To get enough to weigh a single grain requires the treatment of 1,200 pounds of pitchblende. The second form of radium is as a bromide. In this form it costs $5,000 a grain and could a pound be obtained its value would be three-and-a-half million dollars. Radium, as we understand it in any of its compounds, can communicate its property of radio-activity to other bodies. Any material when placed near radium becomes radio-active and retains such activity for a considerable time after being removed. Even the human body takes on this excited activity and this sometimes leads to annoyances as in delicate experiments the results may be nullified by the element acting upon the experimenter's person.