
340 RADIO-ACTIVE PROCESSES [CH. 
observed over the period of one month. The activity measured 
by the 8 and y rays was somewhat reduced, but this was not due 
to a decrease of the radio-activity, but to an increased absorption 
of the 8 rays in their passage through the solution. The volume 
of the solution was at least 1000 times greater than that of the 
solid radium bromide, and, in consequence, the radium was sub- 
jected to the action of a much weaker radiation. I thmk we may 
conclude from this experiment that the radiations emitted by 
radium have little if any influence in causing the disintegration 
of the radium atoms. ‘ 
This result is in general agreement with other observations ; 
for it has not been observed that the decay of activity of any 
product is influenced by the degree of concentration of that 
product. 
It thus seems likely that the cause of the disruption of the 
atoms of the radio-elements and their products is resident in the 
atoms themselves. According to the modern views of the consti- 
tution of the atom, it is not so much a matter of surprise that 
some atoms disintegrate as that the atoms of the elements are so 
permanent as they appear to be. In accordance with the hypothesis 
of J. J. Thomson, it may be supposed that the atoms consist of a 
number of small positively and negatively charged particles in 
rapid internal movement, and held in equilibrium by their mutual 
forces. In a complex atom, where the possible variations in the 
relative motion of the parts are very great, the atom may arrive 
at such a phase that one part acquires sufficient kinetic energy - 
to escape from the system, or that the constraining forces are 
momentarily neutralised, so that the part escapes from the system 
with the velocity possessed by it at the instant of its release. 
Sir Oliver Lodge? has advanced the view that the instability of 
the atom may bea result of radiation of energy by the atom. Larmor 
has shown that an electron, subject to acceleration, radiates energy 
at a rate proportional to the square of its acceleration. An electron 
moving uniformly im a straight line does not radiate energy, but 
an electron, constrained to move in a circular orbit with constant 
velocity, is a powerful radiator, for in such a case the electron is 
continuously accelerated towards the centre. Lodge considered. 
1 Lodge, Nature, June 11, p. 129, 1903. 
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