A Radioactive Substance emitted from Thorium
Compounds by E. RUTHERFORD, M.A., B.SC.,
Macdonald Professor of Physics, McGill University, Montreal From the Philosophical Magazine for January 1900, ser. 5, xlix, pp. 1-14
Communicated by Professor J. J. Thomson, F.R.S. Note: the page numbering is take from "The Collected Works of Lord Rutherford of Nelson," vol. I In order to make clear the evidence of the existence of a radioactive emanation, an account will first be given of the anomalous behaviour of thorium compounds compared with those of uranium. Thorium oxide has been employed in most of the experiments, as it exhibits the 'emanation' property to a greater degree than the other compounds; but what is true for the oxide is also true, but to a less extent, of the other thorium compounds examined, viz. the nitrate, sulphate, acetate, and oxalate. In a previous paper** the author has shown that the radiation from thorium is of a more penetrating character than the radiation from uranium. Attention was also directed to the inconstancy of thorium as a source of radiation. Owens*** has investigated in more detail the radiation from thorium compounds. He has shown that the radiations from the different compounds are of the same kind, and, with the exception of thorium oxide in thick layers, approximately homogeneous in character. The intensity of thoriurn radiation, when examined by means of the electrical discharge produced, is found to be very variable; and this inconstancy is due to slow currents of air produced in an open room. When the apparatus is placed in a closed vessel, to do away with air currcnts, the intensity is found to be practically constant. The sensitiveness of thorium oxide to | |
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