Encyclopaedia Britannica, 11th Edition, "Matter" to "Mecklenburg"

part in 20,000; but since only very small quantities of the emanation

could be used the detection of the change of mass does not seem feasible even in this case.

On the view we have been discussing the existence of potential energy due to an electric field is always associated with mass; wherever there is potential energy there is mass. On the electro-magnetic theory of light,...