Jouy— On the Conservation of Mass. 25 
convection of electrons in the ether,* inertia effects might possibly attend 
change in state of molecular aggregation. This, of course, offers no explanation 
of such results as Herr Heydweiller’s. 
If the original mass is JJ grammes and the final mass M- m grammes, and 
both possess a velocity v (say, the orbital velocity of the Earth), then the kinetic 
energy is greater, of course, for the body M than for the body M—m. In order 
that the kinetic energy should be conserved, we have to assume that the velocity 
v becomes increased to the velocity V, and so that Mv* = (MZ — m)V’. 
From this 
(V+v)(V—-2)= Ce ot 
Mm, 
and writing 2v forV + v, and M for M—m, we have 
If conservation of momentum be looked to, the similar equation will lead to a 
velocity change double of that just obtained. 
If experiment results in showing no change in velocity—in other words, no 
gross dynamical effect—then, as stated above, a variety of hypotheses may be 
advanced to reconcile a true or apparent weight-loss with an apparently unaltered 
inertia. Some reference may be made here to one such speculation. 
It may be suggested that the loss of weight observed in Heydweiller’s 
experiments is due to loss of electrons, which carry with them both weight 
and mass; necessarily resulting in an apparent (but not real) weight-loss 
and perfect constancy of momentum in such experiments as I am describing. 
Such a process as is here supposed would resemble diffusion, and probably would 
not be reversible. There is no evidence, however, to negative the idea that 
by repeated solution of, say, copper sulphate in water and its recrystallization, 
the entire mass, or some constituent of it, can become dissipated. If this is 
the explanation of Heydweiller’s results, so considerable a radiation of electrons 
should reveal itself in physical effects prevailing in the proximity of the reaction. 
Such an explanation leaves the interdependence of mass and weight unquestioned. 
The velocity of the Karth in its orbit is 2°95 x 10° ems. per second, and the 
velocity of a point in the equator due to diurnal rotation 46 x 10° ems. per second. 
At the Jatitude of 53° the diurnal velocity is 2°74 x 10‘ cms. per second. ‘Thus in 
this latitude we have at noon a velocity, east to west, of the orbital less the diurnal, 
at midnight a velocity due to the sum of these motions, and as regards objects on 
the Harth’s surface directed west to east. The noon and midnight velocities may 
be taken as alike for present purposes, and as about 3 x 10° cms. per second. The 
* Professor J. J. Thomson, Phil. Mag., April, 1881. 
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