considerable portion of the whole mass
of water belonging to our globe, and from that source almost every other
body obtains it. It enters into the composition of all animal
substances, and of a great number of minerals; but it is most abundant
in vegetables. From this immense variety of bodies, it is often
spontaneously disengaged; its great levity makes it rise into the
superior regions of the atmosphere; and when, either by an electrical
spark, or any casual elevation of temperature, it takes fire, it may
produce such meteors or luminous appearances as are occasionally seen in
the atmosphere. Of this kind are probably those broad flashes which we
often see on a summer-evening, without hearing any detonation.

EMILY.

Every flash, I suppose, must produce a quantity of water?

CAROLINE.

And this water, naturally, descends in the form of rain?

MRS. B.

That probably is often the case, though it is not a necessary
consequence; for the water may be dissolved by the atmosphere, as it
descends towards the lower regions, and remain there in the form of
clouds.

The application of electrical attraction to chemical phenomena is likely
to lead to many very interesting discoveries in meteorology; for
electricity evidently acts a most important part in the atmosphere. This
subject however, is, as yet, not sufficiently developed for me to
venture enlarging upon it. The phenomena of the atmosphere are far from
being well understood; and even with the little that is known, I am but
imperfectly acquainted.

But before we take leave of hydrogen, I must not omit to mention to you
a most interesting discovery of Sir H. Davy, which is connected with
this subject.

CAROLINE.

You allude, I suppose, to the new miner's lamp, which has of late been
so much talked of? I have long been desirous of knowing what that
discovery was, and what purpose it was intended to answer.

MRS. B.

It often happens in coal-mines, that quantities of the gas, called by
chemists _hydro-carbonat_, or by the miners _fire-damp_, (the same from
which the gas-lights are obtained,) ooze out from fissures in the beds
of coal, and fill the cavities in which the men are at work; and this
gas being inflammable, the consequence is, that when the men approach
those places with a lighted candle, the gas takes fire, and explosions
happen which destroy the men and horses employed in that part of the
colliery, sometimes in great numbers.

EMILY.

What