Page:Popular Science Monthly Volume 78.djvu/582

572 losing electrons and, therefore, atomic weight, until, a certain critical point being reached, a readjustment takes place resulting in transmutation to a lower element, it may be supposed that the atomic weights of the elements may vary in different worlds of space. The more or less uniform weights found on this planet would be due to the fact that the period of formation was practically identical in all cases. The slight divergences between the theoretical and actual atomic weights in the periodic system would be due to the electron contents having fallen below the contents at the last points of readjustment. The list of the chemical elements arranged in decreasing order of their atomic weights would represent the steps of the degradation from the highest elements having, possibly, atomic weights exceeding 250. It was further suggested that the atomic weights of the elements in meteorites be determined to check the truth of the theory of transmutation by disintegration; as far as known this has not yet been attempted.

It would seem to be rather idle to discuss the possible reasons for the diversity of elements in each chemical group on the assumption that they all originated at one time for each individual body in space from extremely dense elements, themselves concentrates of the one primal element. At most, it is proper to state the theory as follows. As the nucleus of a nebula condenses and cools into a solid mass, the structure of the matter at the center becomes extremely dense and the atomic weights are high; these weights taper off to the surface, which is then of a somewhat irregular and slag-like nature like the crust of the earth and brings to mind many parallel cases in metallurgy. Many scientists hold that the earth has solidified more or less in the shape of a modified tetrahedron; if this be true, it encourages the view of a fairly homogeneous core which may be composed of elements even heavier than radium, thorium and uranium. The radioactive properties of these elements may account for the internal heat of the earth. The view that the bulk of this globe of ours is of similar composition to the crust is not only unjustifiable, but highly improbable; the slag of a steel-making process is a good indication of what there is not underneath. The theory of a core composed of elements having high atomic weights will go far to explain the high average density of the earth as compared with that of the crust.

A discovery of inestimable value is due to Kaufmann; he found that the mass of the $$\alpha$$ particle varied with the velocity. This discovery all but consecrated the old theory that mass, that gravitation, is a form of energy, a mode of motion. There can not be a manifestation of energy when the motion is uniform. No motion of energy can be evidenced without acceleration followed by arrest and a reversal of motion, or