26 Jouy—On the Conservation of Mass. 
fact that the velocities are oppositely directed is of much value, obviously, in dis- 
eriminating among true and spurious effects. We have further the facts that at 
6 o’clock in the afternoon and at the same hour in the morning the velocity is but 
one per cent. of the mid-day velocity, and directed west to east. ‘The solar drift 
towards Hercules is estimated to be as much as 246 x 10* ems. per second,* and 
is directed northward at a high angle, about 55°, with the Kcliptic. Much lower 
values for the velocity are, however, sometimes given. The effect will be to 
increase the space-velocity of the Harth in spring-time and diminish it in autumn, 
and that by an amount which may be very considerable. In the estimates which 
follow, I leave the solar drift out of account. 
To arrive at an idea of the magnitude of the effects we are exploring, we may 
refer to Heydweiller’s results as a basis. ‘Take those on the solution of ordinary 
copper sulphate in water. The total reacting masses amount to 209 grammes, of 
which 0:126 mgr. disappears, or, say, 01 mgr. in 200 grms. But the process of 
solution extends necessarily over a certain duration of time. Suppose we powder 
the solid so finely that the added water becomes saturated almost as fast as it 
reaches the solid, and that the time of flow is 60 seconds. In this case, then, the 
mass disappearing per second is 
— = hey IO’ earings, 
Now, on the assumption that 
Bae 
2M 
i.e. that the directed kinetic energy is conserved as such, we have 
7 se Or? se B se IOP 
2 x 200 
= 1:27 x 10° ems. per second. 
This is the acceleration acting during the first 60 seconds. 'The corresponding 
accelerating force is 2°54 dynes. If we now assume that the mode of observation 
involves the use of a counterpoise of equal mass to the reacting substances, and 
that the necessary containing vessels and their counterpoising masses amount to 
50 grms. more, the total mass which has to be accelerated by the force derived as 
above is 450 grms. If the motion is rectilinear and without opposing resistance, 
the acceleration of the total mass will be 5:6 x 10% ems. per second per second, 
and the space described during the 60 seconds will be a little over 10 cms. 
This same large effect, derived on the basis of the supposed weight-loss, is 
obtained with less or greater quantities of reacting substance, if the mass which it 
is necessary to confer on the containing vessel is proportional to the mass of active 
* See G. H. Knibbs, Proc. R. 8., New South Wales, 1900, vol. xxxiv., p. 148, et seq. 
