Radium, its physics & therapeutics / by Dawson Turner.

Date:
1911
Catalogue details

Licence: In copyright

Credit: Radium, its physics & therapeutics / by Dawson Turner. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    to be 226, and its spectrum characteristic of the alkaline earths. The pure metal has recently been isolated by Mme. Curie and M. Debierne, but we know it chiefly in the form of its compounds. These are the bromide, chloride, nitrate, sulphate, and carbonate ; the first three are soluble, the last two are insoluble. When, therefore, we speak of pure radium, we mean the pure salt, and of these the bromide is the commonest. Radio-active Substances.—The radio-active sub- stances separated, of reasonably slow period of trans- formation, are—uranium, thorium, radium, actinium, ionium, and radiolead (radium D). Of other radio-active substances of shorter life there are—polonium, radiothorium, mesothorium; in addition to these there are a large number of other substances like the radium emanation, radium A, B, C, thorium X, and many others, which have a period of transformation measured in days or weeks. These bodies are distinguished from such substances as radium by the difference in their period of transforma- tion and in their chemical and physical properties. The period of an emanation means the time re- quired for its activity to fall to half value. All of these substances are of high atomic weight, and the value 226 places radium in the position of the third known heaviest element; uranium leading the way with an atomic weight of 238, and thorium coming next with an atomic weight of 232. Probably there are other bodies which are radio-