ther that is true.
You all know the peculiar clearness which precedes rain,--when the
distant hills are looking nigh. I take it on trust from the
scientific people that there is then a quantity--almost to
saturation--of aqueous vapor in the air, but it is aqueous vapor in
a state which makes the air more transparent than it would be
without it. What state of aqueous molecule is that, absolutely
unreflective[12] of light--perfectly transmissive of light, and
showing at once the color of blue water and blue air on the distant
hills?

I put the question--and pass round to the other side. Such a
clearness, though a certain forerunner of rain, is not always its
forerunner. Far the contrary. Thick air is a much more frequent
forerunner of rain than clear air. In cool weather, you will often
get the transparent prophecy: but in hot weather, or in certain not
hitherto defined states of atmosphere, the forerunner of rain is
mist. In a general way, after you have had two or three days of
rain, the air and sky are healthily clear, and the sun bright. If
it is hot also, the next day is a little mistier--the next misty
and sultry,--and the next and the next, getting thicker and
thicker--end in another storm, or period of rain.

I suppose the thick air, as well as the transparent, is in both
cases saturated with aqueous vapor;--but also in both, observe,
vapor that floats everywhere, as if you mixed mud with the sea; and
it takes no shape anywhere: you may have it with calm, or with
wind, it makes no difference to it. You have a nasty haze with a
bitter east wind, or a nasty haze with not a leaf stirring, and you
may have the clear blue vapor with a fresh rainy breeze, or the
clear blue vapor as still as the sky above. What difference is
there between _these_ aqueous molecules that are clear, and those
that are muddy, _these_ that must sink or rise, and those that must
stay where they are, _these_ that have form and stature, that are
bellied like whales and backed like weasels, and those that have
neither backs nor fronts, nor feet nor faces, but are a mist--and
no more--over two or three thousand square miles?

I again leave the questions with you, and pass on.

Hitherto I have spoken of all aqueous vapor as if it were either
transparent or white--visible by becoming opaque like snow, but not
by any accession of color. But even those of us who are least
observant of skies, know that, irrespective of all supervening
colors fro