Philosophical Transactions of the Royal Society of London: Containing papers of a mathematical or physical character. Series A, Volume 204

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The Society, 1905 - Mathematics

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Page 57 - As a unit of resistance, the international ohm, which is based upon the ohm, equal to 109 units of resistance of the Centimeter-Gramme-Second System of electro-magnetic units, and is represented by the resistance offered to an unvarying electric current by a column of mercury at the temperature of melting ice 14-4521 grammes in mass, of a constant cross-sectional area, and of the length of 106-3 centimeters.
Page 186 - ... matter B is initially zero, and in this particular case passes through a maximum about 10 minutes later, and then diminishes with the time. In a similar way, the amount of C passes through a maximum about 35 minutes after removal.
Page 177 - The initial drop decays very approximately according to an exponential law with the time, falling to half value in about 3 minutes. Three or 4 hours after removal the activity again decays according to an exponential law with the time, falling to half value in about 28 minutes. These results thus indicate : — (1) An initial change in which half the matter is transformed in 3 minutes; (2) A final change in which half the matter is transformed in 28 minutes. Before considering the explanation of...
Page vii - Angularity of the subjects, or the advantageous manner of treating them, without pretending to answer, or to make the Society answerable, for the certainty of the facts, or propriety of the reasonings, contained in the several Papers so published, - which must still rest on the credit or judgment of their respective Authors.
Page 58 - THE ELECTRICAL STANDARDS COMMITTEE OF THE BRITISH ASSOCIATION, August 9, 1892. The following resolutions were agreed to : — 1. That the resistance of a specified column of mercury be adopted as the practical unit of resistance.
Page 211 - The similarity of the a particles from the different radio-elements indicates that they consist of expelled particles of the same kind. On this view, helium should be produced by each of the radio-elements. The presence of helium in minerals such as thorium, for example, in monazite sand, and the Ceylon mineral described by RAMSAY, suggests that helium is a product of thorium as well as of radium. Taking the view that the a particles are projected helium atoms, we must regard the atoms of the radio-elements...
Page 187 - It is, at first sight, a somewhat unexpected result that the final rate of decay of the active deposit from thorium does not in reality give the rate of change of the last product itself, but of the preceding product, which does not give rise to rays at all. A similar peculiarity is observed in the decay of the excited activity of actinium, which is discussed in section 1 5.
Page 208 - I think that it is more than a coincidence that the ft and y rays appear only in the last of the rapid changes in the three radio-elements. It appears probable that the ft particle, which is finally expelled, may be regarded as the active agent in promoting the disintegration of the radio-atom in successive stages. According to the modern point of view of regarding atomic structure, the atoms of the radio-element may be supposed to be made up of electrons (ft particles) and groups of electrons (a...
Page vii - It is likewise necessary on this occasion to remark, that it is an established rule of the Society, to which they will always adhere, never to give their opinion, as a Body, upon any subject, either of Nature or Art, that comes before them.

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