lie says : " We know that the positive ions in gases carry the same charge as the negative, and that they have an enormously greater mass. Unless, therefore, their velocity is smaller out of all proportion than the negative ions, it is to be expected that they will 1)0 much less easily deflected by the magnet. . . . Next it may be noticed that the smaller penetrating power would be well accounted for by the size of the positive ions, which would, of course, make more collisions with the molecules of the surrounding gas than the much smaller negative ions."
Of the three radio-active bodies, radium, actinium, and polonium, actinium appears to emit corpuscles almost entirely of the penetrat- ing, deflectable kind, polonium rays of the non-deflectable, non-pene- trating kind, whilst radium emits rays of both kinds.
On the above hypothesis corpuscles from polonium might consist of the heavy positive ions : to test the accuracy of this inference experi- ments are now in progress.
Some curious and far-reaching inferences may be drawn from Mr. Strutt's view, supposing it to be correct, that positive as well as negative corpuscles will fly oft' from a radio-active body. In a paper " On Electrical Evaporation "[1] I showed that many bodies, such as silver, gold, platinum, Arc., usually considered non-volatile at ordinary temperatures, easily volatilise in a vacuum if connected with the negative pole of an induction coil, remaining fixed when connected with the positive pole. This phenomenon was first ob- served by Dr. Wright, of Yale College, and was applied by him for the production of mirrors for physical apparatus. It is shown by experiments that the action in the vacuum tube is of two kinds. A silver pole was used, and near it, in front, was a sheet of mica with a hole in its centre. The vacuum was very high (P = O'OOOGK mm.), and when the poles were connected with the coil, the silver being negative, electrons shot from it in all directions, and passing through the hole in the mica screen, formed a bright phosphores- cent patch on the opposite side of the bulb. The action of the coil was continued for some hours, to volatilise a certain portion of the silver. On subsequent examination it was found that silver had been deposited only on the mica screen and in the immediate neigh- bourhood of the pole; the far end of the bulb, at the spot which had been glowing for hours from the impact of electrons, being free from silver deposit. Here then are two simultaneous actions. Electrons, or as I once called them " Radiant Matter," shot from the negative pole, and caused the glass against which they struck to glow with phosphorescent light. Simultaneously the heavy posi- tive ions of silver, freed from their negative electrons, or under the
- ↑ 'Roy. Soc. Proc.,' vol. 50, p. 88, June, 1891.
