Provide a glass tube, about three feet long and half an inch in
diameter, nearly fill it with water, upon the surface of which pour a
little coloured ether; then close the open end of the tube carefully
with the palm of the hand, invert it in a basin of water, and rest
the tube against the wall: the ether will rise through the water to
the upper end of the tube; pour a little hot water over the tube, and
it will soon cause the ether to boil within, and its vapour may thus
be made to drive nearly all the water out of the tube into the basin;
if, however, you then cool the tube by pouring cold water over it, the
vaporized ether will again become a liquid, and float upon the water as
before.