Journal of the Chemical Society, Volume 81, Part 2 |
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Page 842 - This view, however, can be shown to be quite untenable, for according to it any precipitate capable of removing thorium completely from its solution should yield active residues similar to those obtained from ammonia. Quite the reverse, however, holds. When thorium nitrate is precipitated by sodium or ammonium carbonate, the residue from the filtrate, after evaporation and ignition, is free from activity, and the thorium carbonate obtained possesses the normal value for its activity.
Page 855 - Disregarding the view that it is a separate phenomenon and not connected with the major part of the activity, two hypotheses can be brought forward capable of experimental test, and in accordance with the views advanced on the nature of radioactivity, to account for the existence of this part. First, if there was a second type of excited activity produced by ThX, similar to that known, but with a very slow rate of decay, it would account for the existence of the non-separable activity. If this is...
Page 846 - VIII) that about 21 per cent, of the normal radioactivity of thorium oxide under ordinary conditions consists of a secondary activity excited on the mass of the material. This portion is, of course, a variable, and since it is divided among the total amount of matter present, the conditions of aggregation, &c., will affect the value of this part.
Page 859 - The position is thus reached that radioactivity is at once an atomic phenomenon and the accompaniment of a chemical change in which new kinds of matter are produced. The two considerations force us to the conclusion that radioactivity is a manifestation of subatomic chemical change.
Page 841 - T? ~ar curve of thorium in which the percentage amounts of activity recovered, reckoned from this 25 per cent, minimum, are plotted as ordinates. In the same figure the decay curve after the second day is shown on the same scale. The activity of ThX decreases very approximately in a geometrical progression with the time...
Page 846 - Thus the rate of recovery of activity under different conditions in thorium compounds affords a direct measure of the rate of production of ThX under these conditions. The following experiments were performed : One part of thorium hydroxide newly separated from ThX was sealed up in a vacuum obtained by a good TOpler pump, and the other part exposed to air. On comparing the samples 12 days later no difference could be detected between them either in their radioactivity or emanating power. In the next...
Page 854 - All of them showed the initial rise of about 15 per cent at the end of 18 hours, and then a normal decay to zero. The position is thus proved that the initial irregularities are caused by the secondary radiation excited by ThX upon the surrounding matter. By suitably choosing the conditions the recovery curve can be made to rise normally from a constant minimum, and the decay curve be shown to consist of two curves, the first, the rate of production of excited radioactivity, and the second, the rate...
Page 859 - ... occur, and the former also in the elementary state. So far as the radioactivity of different compounds of different density and states of division can be compared together, the intensity of the radiation appears to depend only on the quantity of active element present. It is not at all dependent on the source from which the element is derived, or the process of purification to which it has been subjected, provided sufficient time is allowed for the equilibrium point to be reached. It is not possible...
Page 841 - ... speaking generally, the percentage proportion of the lost activity regained by the hydroxide over any given interval is approximately equal to the percentage proportion of the activity lost by the ThX during the same interval. If the recovery curve is produced backwards in the normal direction to cut the vertical axis, it will be seen to do so at a minimum of about 25 per cent, and the above result holds even more accurately if the recovery is assumed to start from this constant minimum, as,...
Page 858 - ... half value in about four days. The constant radioactivity of thorium is maintained by the production of this material at a constant rate. Both the rate of production of the new material and the rate of decay of its activity appear to be independent of the physical and chemical condition of the system. The ThX further possesses the property of exciting radioactivity on surrounding inactive matter, and about 21 per cent of the total activity under ordinary circumstances is derived from this source....
Bibliographic information
| Title | Journal of the Chemical Society, Volume 81, Part 2 |
| Author | Chemical Society (Great Britain) |
| Contributor | Royal Society of Chemistry (Great Britain) |
| Publisher | The Society., 1902 |
| Original from | the University of Michigan |
| Digitized | 19 Jun 2007 |
| Export Citation | BiBTeX EndNote RefMan |