d to be one of the essential properties of matter.
All that is meant by it, however, is simply this: In no physical or
chemical process to which it has been experimentally subjected has there
been any apparent loss. The matter experimented upon may change from a
solid or liquid to a gas, or the molecular change called chemical may
result in new compounds, but the weight of the material and its atomic
constituents have not appreciably changed. That matter cannot be
annihilated is only the converse of the proposition that matter cannot
be created, which ought always to be modified by adding, by physical or
chemical processes at present known. A chemist may work with a few
grains of a substance in a beaker, or test-tube, or crucible, and after
several solutions, precipitations, fusions and dryings, may find by
final weighing that he has not lost any appreciable amount, but how much
is an appreciable amount? A fragment of matter the ten-thousandth of an
inch in diameter has too small a weight to be noted in any balance, yet
it would be made up of thousands of millions of atoms. Hence if, in the
processes to which the substance had been subjected, there had been the
total annihilation of thousands of millions of atoms, such phenomenon
would not have been discovered by weighing. Neither would it have been
discovered if there had been a similar creation or development of new
matter. All that can be asserted concerning such events is, that they
have not been discovered with our means of observation.

The alchemists sought to transform one element into another, as lead
into gold. They did not succeed. It was at length thought to be
impossible, and the attempt to do it an absurdity. Lately, however,
telescopic observation of what is going on in nebulae, which has already
been referred to, has somewhat modified ideas of what is possible and
impossible in that direction. It is certainly possible roughly to
conceive how such a structure as a vortex-ring in the ether might be
formed. With certain polarizing apparatus it is possible to produce rays
of circularly polarized light. These are rays in which the motion is an
advancing rotation like the wire in a spiral spring. If such a line of
rotations in the ether were flexible, and the two ends should come
together, there is reason for thinking they would weld together, in
which case the structure would become a vortex-ring and be as durable as
any other. There is reason for believing, a