100 YEARS AGO

The discovery by Monsieur and Madame Curie that a sample of radium gives out sufficient energy to melt half its weight of ice per hour has attracted attention to the question of the source from which the radium derives the energy necessary to maintain the radiation; this problem has been before us ever since the original discovery by Becquerel of the radiation from uranium. It has been suggested that the radium derives its energy from the air surrounding it, that the atoms of radium possess the faculty of abstracting the kinetic energy from the more rapidly moving air-molecules while they are able to retain their own energy when in collision with the slowly moving molecules of air. I cannot see, however, that even the possession of this property would explain the behaviour of radium... I think that the absence of change in the radium has been assumed without sufficient justification; all that the experiments justify us in concluding is that the rate of change is not sufficiently rapid to be appreciable in a few months. There is, on the other hand, very strong evidence that the substances actually engaged in emitting these radiations can only keep up the process for a short time; then they die out... I have recently found that water from deep wells in Cambridge contains a radio-active gas, and I am anxious to see whether water from other sources possesses the same property. I should be greatly obliged if any of your readers who have access to deep level water would fill a clean two-gallon can with it and forward it to the Cavendish Laboratory. I should, of course, pay the carriage and return the can.

J. J. Thomson

From Nature 30 April 1903.

50 YEARS AGO

Royal Society: Foreign Members. The following have been elected foreign members of the Royal Society: Louis Victor Pierre Raymond, Prince de Broglie (Paris), distinguished for his contributions to quantum theory; Marie Jules Constant Robert Courrier (Paris), distinguished for his contributions to endocrinology; Hermann Joseph Muller (Bloomington, Indiana), distinguished for his contributions to the chromosome theory of heredity; Wolfgang Pauli (Zurich), distinguished for his contributions to theoretical physics, in particular the formulation of the exclusion principle.

From Nature 2 May 1953.