form salt water when it condenses again. This I know by experiment.
The same thing is true in every case of the kind: wine and all
fluids that evaporate and condense back into a liquid state become
water. They all are water modified by a certain admixture, the
nature of which determines their flavour. But this subject must be
considered on another more suitable occasion.
For the present let us say this. The sea is there and some of it
is continually being drawn up and becoming sweet; this returns from
above with the rain. But it is now different from what it was when
it was drawn up, and its weight makes it sink below the sweet water.
This process prevents the sea, as it does rivers, from drying up
except from local causes (this must happen to sea and rivers alike).
On the other hand the parts neither of the earth nor of the sea remain
constant but only their whole bulk. For the same thing is true of
the earth as of the sea: some of it is carried up and some comes
down with the rain, and both that which remains on the surface and
that which comes down again change their situations.
There is more evidence to prove that saltness is due to the
admixture of some substance, besides that which we have adduced.
Make a vessel of wax and put it in the sea, fastening its mouth in
such a way as to prevent any water getting in. Then the water that
percolates through the wax sides of the vessel is sweet, the earthy
stuff, the admixture of which makes the water salt, being separated
off as it were by a filter. It is this stuff which make salt water
heavy (it weighs more than fresh water) and thick. The difference in
consistency is such that ships with the same cargo very nearly sink in
a river when they are quite fit to navigate in the sea. This
circumstance has before now caused loss to shippers freighting their
ships in a river. That the thicker consistency is due to an
admixture of something is proved by the fact that if you make strong
brine by the admixture of salt, eggs, even when they are full, float
in it. It almost becomes like mud; such a quantity of earthy matter is