The paper just communicated to the French Physical Society by
M. Curie on the subject of the heat production of radium is dealt with in an able special article in the Times of Thursday. There can no longer be any doubt that radium, in addition to remarkable powers which it shares in a vastly intensified degree with other substances, possesses a " unique and unprecedented power of emission of heat." M. Curie now shows that this emission is constant until the temperature falls to the fearful cold of liquid hydrogen—that is to say, approaches to absolute zero—when the emission is increased. This is an unprecedented fact. The Times correspondent declares that " these remarkable results throw no light upon the process by which radium maintains its constant emission of heat and radio-activity." But is this so ? If radio-activity is due to the constant breaking up of a very small number of the radium atoms, is it not likely, in the vicinity of the absolute zero, that there would be an increased tendency for the stored potential energy to convert itself into heat; in other words, for a larger number of atoms to shrink and dissolve P In fact, M. Curie's experiment appears to confirm the hypothesis put forward by Sir Oliver Lodge in his Romanes Lecture, that the emission of heat is due to the collapsing of the electrical constituents of a radium atom, and would seem to dispose of the possible suggestions that radium utilises the most quickly moving atoms of air or the fund of electricity surrounding the earth, It would, we suppose, be physically impossible to show that at great temperatures the emission decreases.
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