amount? I have sometimes thought that a lady's portmanteau
would contain it all. I have thought that even a gentleman's
portmanteau--possibly his snuff-box--might take it in. And, whether
the actual sky be capable of this amount of condensation or not, I
entertain no doubt that a sky quite as vast as ours, and as good in
appearance, could be formed from a quantity of matter which might be
held in the hollow of the hand.

Small in mass, the vastness in point of number of the particles of our
sky may be inferred from the continuity of its light. It is not in
broken patches, nor at scattered points, that the heavenly azure is
revealed. To the observer on the summit of Mont Blanc, the blue is as
uniform and coherent as if it formed the surface of the most
close-grained solid. A marble dome would not exhibit a stricter
continuity. And Mr. Glaisher will inform you, that if our
hypothetical shell were lifted to twice the height of Mont Blanc above
the earth's surface, we should still have the azure overhead.
Everywhere through the atmosphere those sky-particles are strewn. They
fill the Alpine valleys, spreading like a delicate gauze in front of
the slopes of pine. They sometimes so swathe the peaks with light as
to abolish their definition. This year I have seen the Weisshorn thus
dissolved in opalescent air. By proper instruments the glare thrown
from the sky-particles against the retina may be quenched, and then
the mountain which it obliterated starts into sudden definition.
[Footnote: See the 'Sky of the Alps,' Art. iv. sec. 3, vol. i.]
Its extinction in front of a dark mountain resembles exactly the
withdrawal of a veil. It is then the light taking possession of the
eye, not the particles acting as opaque bodies, that interferes with
the definition. By day this light quenches the stars; even by
moonlight it is able to exclude from vision all stars between the
fifth and the eleventh magnitude. It may be likened to a noise, and
the feebler stellar radiance to a whisper drowned by the noise.

What is the nature of the particles which shed this light? The
celebrated De la Rive ascribes the haze of the Alps in fine weather to
floating organic germs. Now the possible existence of germs in such
profusion has been held up as an absurdity. It has been affirmed that
they would darken the air, and on the assumed impossibility of their
existence in the requisite numbers, without invasion of the solar
light, an appa