particles_, or from vapor in a state of _very high condensation_, and
also that beyond doubt other portions of the comet's light issue from
the vapor _shining by its own inherent light_. The light coming from
the more dense constituents, and therefore giving a continuous
colored spectrum, was, however, deficient in blue rays, and was most
probably emitted _by material substance at the low red and yellow
stages of incandescence_."

Padre Secchi, at Rome, believed he saw in the comet "carbon, or an
oxide of carbon, as the source of the bright luminous bands," and the
Abbé Moigno asks whether this comet may not be, after all, "_un
gigantesque diamant volatilisé_."

"Whatever may be the answer hereafter given to that question, the
verdict of the spectroscope is clearly to the effect that the comet
is made up of a _commingling of thin vapor and of denser particles_,
either compressed into the _condition of solidification_, or into
some physical state approaching to that condition, and is therefore
entirely in accordance with the notion formed on other grounds that
the nucleus of the comet is a _cluster of solid nodules or granules_,
and that the luminous coma and tail are jets and jackets of vapor,
associated with the more dense ingredients, and _swaying and
streaming about them as heat and gravity, acting antagonistic ways,
determine_."[1]

[1. "Edinburgh Review," October, 1874, p. 210.]

{p. 67}

If the comet shines by reflected light, it is pretty good evidence