e component, are shown on the
third strip. The next line is split by the magnetic field into
twelve components, four of which appear in the second strip and
eight in the third. The magnetic fields in sun-spots affect these
lines in precisely the same way.]

It is interesting to follow our line of reasoning to the stars,
which differ widely in temperature at various stages in their
life-cycle.[*] A sun-spot is a solar tornado, wherein the intensely
hot solar vapors are cooled by expansion, giving rise to the compounds
already named. A red star, in Russell's scheme of stellar evolution,
is a cooler sun, vast in volume and far more tenuous than atmospheric
air when in the initial period of the "giant" stage, but compressed
and denser than water in the "dwarf" stage, into which our sun has
already entered as it gradually approaches the last phases of its
existence. Therefore we should find, throughout the entire atmosphere
of such stars, some of the same compounds that are produced within
the comparatively small limits of a sun-spot. This, of course,
on the correct assumption that sun and stars are made of the same
substances. Fowler has already identified the bands of titanium
oxide in such red stars as the giant Betelgeuse, and in others
of its class. It is safe to predict that an interesting chapter
in the chemistry of the future will be based upon the study of
such compounds, both in the laboratory and under the progressive
temperature conditions afforded by the countless stellar "giants"
and "dwarfs" that precede and follow the solar state.

[Footnote *: See Chapter II.]

[Illustration: Fig. 35. Electric furnace in the Pasadena laboratory
of the Mount Wilson Observatory.

With which the chemical phenomena observed in sun-spots and red
stars are experimentally imitated.]

ASTROPHYSICAL LABORATORIES

It is precisely in this long sequence of physical and chemical
changes that the astrophysicist and the astrochemist can find the
means of pushing home their attack. It is true, of course, that
the laboratory investigator has a great advantage in his ability
to control his experiments, and to vary their progress at will.
But by judicious use of the transcendental temperatures, far out
ranging those of his furnaces, and extreme conditions, which he
can only partially imitate, afforded by the sun, stars, and nebulae,
he may greatly widen the range of his inquiries. The sequence of
phenomena seen during the growth of a