e is a more or less apparent simultaneous concurrence of these
causes.

In order to explain electric or magnetic phenomena, and also those of
crystallization, it is admitted that the atoms of which bodies are
composed are surrounded, each of them, with a sort of atmosphere
formed of electric currents, owing to which these atoms are attracted
or repelled on certain sides, and produce those varied effects that we
observe under different circumstances. According to this theory, then,
atoms would be small electro-magnets behaving like genuine magnets.
Entirely free in gases, but less so in liquids and still less so in
solids, they are nevertheless capable of arranging themselves and of
becoming polarized in a regular order, special to each kind of atom,
in order to produce crystals of geometrical form characteristic of
each species. Thus, as Mr. Saigey remarks in "Physique Moderne" (p.
181): "So long as the atmospheres of the molecules do not touch each
other, no trace of cohesion manifests itself; but as soon as they come
together force is born. We understand why the temperatures of fusion
and solidification are fixed for the same body. Such effects occur at
the precise moment at which these atmospheres, which are variable with
the temperature, have reached the desired diameter."

[Illustration: Figs. 1., 2., and 3.]

Although the phenomenon of crystallization does not essentially depend
upon temperature, but rather upon the relative quantity of liquid that
holds the substance in solution, it will be conceived that a moment
will arrive when, the liquid having evaporated, the atmospheres will
be close enough to each other to attract each other and become
polarized and symmetrically juxtaposed, and, in a word, to
crystallize.

Before giving examples of the production of electricity in the
phenomenon of crystallization, it will be well to examine, beforehand,
the different circumstances under which electricity acts as the
determining cause of crystallization or intervenes among the causes
that bring about the phenomenon. In the first place, two words
concerning crystallization itself: We know that crystallization is the
passage, or rather the result of the passage, of a body from a liquid
or gaseous state to a solid one. It occurs when the substance has lost
its cohesion through any cause whatever, and when, such cause ceasing
to act, the body slowly returns to a solid state.

Under such circumstances, it may take on re