e increase the volume of a body we decrease the density, the
total mass of the body remaining the same.

If the volume be doubled, then the density of the body would be halved,
and _vice versa_, but through all the changes of volume and density that
may arise from the addition of heat or diminution of heat, the total
mass of a body always remains the same. Looked at from the atomic
standpoint, taking hydrogen as unity, an atom of oxygen would always
weigh sixteen times an atom of hydrogen, and this principle applies
throughout the whole realm of the atomic world. Further, the same
principle or law, that the mass is equal to the volume multiplied by the
density, is true of the planetary or even the stellar world. Thus the
great regulating principle of the attractive force of gravity is mass,
and not volume, or density, or any other condition.

Now as Aether is subject to the attractive force of gravity, the extent
of the aetherial field, and the density of the Aether near the surface
of any body, must be subject to the same law regarding mass. That is,
the aetherial atmosphere of any atom, or molecule, or satellite, or
planet, or star is dependent upon the mass of the atom, the molecule, or
the planet, or the star as the case may be.

Thus an atom of oxygen would have a larger or denser aetherial
atmosphere than an atom of hydrogen, exactly proportionate to their
respective masses. A planet whose mass was represented by 1,000,000 tons
would have twice the quantity of Aether around it, compared to a planet
weighing only 500,000 tons, and so on, the aetherial atmosphere always
being proportionate to the mass of the planet, or the satellite, or the
sun, or the star. The fact which we learn from these considerations is
that the quantity of Aether, which is attracted by any body, is always
proportionate to the mass of the body attracting it.

But we have learned from Art. 78 that Aether has an electro-magnetic
basis, and that the density of the Aether is co-equal with electric
density, so that the quantity of Aether which is attracted and held
bound by any body is really equal to the quantity of electricity that
such a body is covered with, or is charged with. If the quantity of
Aether around any body is doubled because its mass is doubled, then the
quantity of electricity is also doubled, but as long as the mass remains
unaltered, the quantity of electricity held bound by that mass remains
unaltered also. The area of the