. Radio-activity : an elementary treatise from the standpoint of the disintegration theory . eases until the strainbecomes too great and the glass of the tubeis punctured, as in the case of an over-chargedLeyden jar. Several cases are on record inwhich sealed tubes of active radium prepara-tions have shattered with the accompanimentof a bright spark and explosion after havingbeen kept sealed up for some months. Kaufmann {Nachrichten der K. Wiss. zu Gottingen, 1901, No. 2) hasmeasured both v and ejifn for the more pene-trating kinds of ^-rays emitted by radium, and obtained forV val
. Radio-activity : an elementary treatise from the standpoint of the disintegration theory . eases until the strainbecomes too great and the glass of the tubeis punctured, as in the case of an over-chargedLeyden jar. Several cases are on record inwhich sealed tubes of active radium prepara-tions have shattered with the accompanimentof a bright spark and explosion after havingbeen kept sealed up for some months. Kaufmann {Nachrichten der K. Wiss. zu Gottingen, 1901, No. 2) hasmeasured both v and ejifn for the more pene-trating kinds of ^-rays emitted by radium, and obtained forV values between 2-36 and 283 x 10^°—, between 80 and95 per cent, of the velocity of light, Now, it has already beenpointed out (p. 54) that if the mass of the corpuscle iselectrical in origin and due to the inertia of the moving charge,it should, theoretically, tend to increase as the velocity of lightis approached, and becorae infinite when that value is Kaufmann found that the ratio ejiii decreased from1-31 X 10^ when v = 2-36 x 10^^ to 0-fi3 x 10^ when ?;=2-83 x 10^°,. Fig. 19. THE a, /3 AND y-RA YS. to and these results are in good agreement with the theory thatthe mass of the corpuscle or electron—, the negative atomiccharge, which constitutes the cathode ray and the ^-raysfrom radio-active substances—is, at least mainly, electrical inorigin. a-rays.—These are given out by all radio-active sub-stances, with the possible exception of uranium X (p. 85),and, although the least striking, are much the most impor-tant of the three types, representing, in each case, asRutherford has shown, by far the greater part of the totalenergy radiated. In measurements by the electrical method,unless special precautions are adopted, the effect of the /?and y-rays is negligible compared with that of the a-rays.
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