Grant that we have discovered particles—in round numbers one thousandth part the size and weight of the hydrogen atom—the argument is still not complete for the divisibility of the atom. Perhaps we have found a new element. But cathode rays were produced under circumstances where they must have arisen from the cathode itself, and it is hard to escape from the conclusion that the atoms of the cathode disintegrated to a certain extent to furnish these particles. Furthermore, rays have been studied having as their sources different metals under the influence of electrical currents, different metals heated to incandescence, flames of different kinds and ultra-violet light; and these rays appear to consist of corpuscles of the same weight, no matter what their source. This makes it difficult to escape from the further conclusion that atoms of a great variety of natures are capable of disintegrating and of furnishing the same product by the disintegration;[1] and this is as much as to say that instead of about eighty different elements we have one 'mother substance,' and Prout's hypothesis is once more very much alive, somewhat modified, it is true, and in a new garb, better suited to the present fashions.
It remains to rehearse briefly the evidence to be obtained from radio-active phenomena. In the first place, the rays incessantly sent out from these extraordinary substances consist, at least in part, of rays like the cathode rays, and are streams of the same kind of corpuscles, but, on the whole, traveling with greater velocities than the corpuscles of the cathode rays. It has been proved by Rutherford and Soddy that the emission of the radiations from these substances is accompanied by a disintegration, or decay, as they describe it, of the substances themselves. These investigators have caught some of the products of this decay and have studied their properties. These products themselves decay, some slowly, some rapidly, sending forth other rays and furnishing new products to decay in turn. Indeed each new issue of a scientific journal for the past few years seems to chronicle the birth, life and death of a fresh radio-active substance. The rate at which new offspring of radium, thorium and allied elements are discovered and studied during their fleeting existences reminds one of nothing so much as the genealogy of Noah as given in the fifth chapter of Genesis.[2]
- ↑ Experimental details, and also comprehensive treatments of the subject as a whole and of special parts, may be found in three books by J. J. Thomson: 'The Discharge of Electricity through Gases' (based on lectures given at Princeton University in October, 1896); 'Conduction of Electricity through Gases' (a larger book); 'Electricity and Matter' (lectures delivered at Yale University in 1903).
- ↑ It is an indication of the widespread interest in this subject, and of the activity of the workers in this field, that one journal, in the year 1905, contained no less than 167 abstracts of articles upon radioactive phenomena. E. Rutherford's book, 'Radio-activity,' 2d edition, 1905, is a masterly survey of the whole subject.
