I have been continuously engaged upon the chemical examination and preparation of these substances. I effected the fractionations necessary to the concentration of radium, and I succeeded in isolating pure radium chloride. Concurrently with this work, I made several atomic weight determinations with a very small quantity of material, and was finally able to determine the atomic weight of radium with a very fair degree of accuracy. The work has proved _that radium is a new chemical element_. Thus the new method of investigating new chemical elements, established by M. Curie and myself, based upon radio-activity, is fully justified. I have investigated the law of absorption of polonium rays, and of the absorbable rays of radium, and have demonstrated that this law of absorption is peculiar and different from the known laws of other radiations. I have investigated the variation of activity of radium salts, the effect of solution and of heating, and the renewal of activity with time, after solution or after heating. In conjunction with M. Curie, I have examined different effects produced by the new radio-active substances (electric, photographic, fluorescent, luminous colourations, &c.). In conjunction with M. Curie, I have established the fact that radium gives rise to rays charged with negative electricity. Our researches upon the new radio-active bodies have given rise to a scientific movement, and have been the starting-point of numerous researches in connection with new radio-active substances, and with the investigation of the radiation of the known radio-active bodies. ------------------------------------------------------------------------ RADIUM AND OTHER RADIO-ACTIVE ELEMENTS. A Popular account of Radium and other Radio-active Elements treated experimentally. Including a number of Radium Photographs and other Illustrations. By LEONARD A. LEVY and HERBERT G. WILLIS. PRICE 2s. 6d. net; post free 2s. 9d. CONTENTS. INTRODUCTION.—Chap. I. The Discovery of Radium; its Extraction.—Chap. II. The Radium Emanation.—Chap. III. Physical Effects (Electrical and Magnetic).—Chap. IV. Physical Effects (continued).—Chap. V. Chemical Effects.—Chap. VI. Actions on Animal Life and Living Tissues.—Chap. VII. Other Radio-active Elements.—Appendix.—Experimental Apparatus. PERCIVAL MARSHALL & CO., 26–29, POPPIN’S COURT, FLEET STREET, LONDON, E.C. * * * * * RADIUM SPINTHARISCOPES. AS DESIGNED BY SIR WILLIAM CROOKES, F.R.S., For Demonstrating the Radio-activity of Radium. KUNZITE. THE NEW MINERAL. Responding in a high degree to the Emanations from Radium.