286 ANNUAL, REPORT SMITHSONIAN INSTITUTION, 1910. 



of matter and negative electrons would give atoms electrically neu- 

 tral, and that the positive charges would result only from the absence 

 of negative electrons; this view of the case, however, a view which 

 is intermediate between the old and the new ideas, loses all the ad- 

 vantages of simplicity and unification resulting from the modern 

 conceptions, which attributes everything to the ether. 



A vital factor in these considerations must be noted in the emana- 

 tion of helium in the form of X rays from all radioactive bodies, and 

 it must not be forgotten that Sir J. J. Thomson has found these 

 same X ra} r s in the canalstrahlen tubes. The helium ion can not, 

 however, be the positive electron because there exists a material 

 atom, that of hydrogen, which possesses a smaller mass; still the 

 atom of helium presents a grouping of very great stability. Wh ether 

 it is formed in the preceding phenomena by the direct combination 

 of negative electrons with positive electrons freed at just that instant, 

 or whether it appears as a primordial grouping in the constitution 

 of the atoms of most of the elements are questions which can not at 

 present be answered. 



In the canalstrahlen particles characteristic of the hydrogen ion 

 are also found. We can go back to the ideas of Prout and suppose 

 that this ion is nothing else than the positive electron. It would be 

 necessary to know, then, whether its mass is purely electromagnetic. 

 If this is so, the positive electron would have a mass 2,000 times 

 that of the negative electron, and the atom of hydrogen would be 

 the result of the union of a single positive electron with a single 

 negative electron. 



Still another hypothesis has been proposed; some physicists who 

 have found great difficulty in explaining the properties of metals by 

 means of negative electrons alone have imagined the existence of two 

 sorts of electrons differing only in the sign of their charges. 



I should like to say a few words here about some quite recent ex- 

 periments made in our laboratory, for which there has been found no 

 simple explanation in the idea of negative electrons, but which could 

 be interpreted in a simpler way if there were positive electrons in the 

 make-up of bodies. These experiments had to do with the action of 

 a magnetic field on the absorption bands of crystals and of certain 

 dissolved salts. The change of period produced by the magnetic field 

 took place in certain bands in the direction which would correspond 

 to negative electrons, but manifested itself in the opposite direction 

 with other bands. 



The size of the change of period which is absolutely independent of 

 changes of temperature (as far as —259°) appears to be characteristic 

 of a vibrant system. All these phenomena seem to indicate that cer- 

 tain of these systems may contain positive electrons. 1 



1 Projection of a slide showing this phenomenon in a group of bands of Xenotinc .it 

 -259°. 



