possible, and even extremely probable, that, both at the first creation,
and every day, gasses are formed, which are difficultly miscible with
atmospheric air, and are continually separating from it. If these gasses
be specifically lighter than the general atmospheric mass, they must, of
course, gather in the higher regions, and form strata that float upon
the common air. The phenomena which accompany igneous meteors induce me
to believe, that there exists in the upper parts of our atmosphere a
stratum of inflammable fluid in contact with those strata of air which
produce the phenomena of the aurora borealis and other fiery meteors.--I
mean hereafter to pursue this subject in a separate treatise.
FOOTNOTES:
[8] The degree of pressure which they undergo must be taken into
account. E.
CHAP. III.
_Analysis of Atmospheric Air, and its Division into two Elastic Fluids;
the one fit for Respiration, the other incapable of being respired._
From what has been premised, it follows, that our atmosphere is composed
of a mixture of every substance capable of retaining the gasseous or
aeriform state in the common temperature, and under the usual pressure
which it experiences. These fluids constitute a mass, in some measure
homogeneous, extending from the surface of the earth to the greatest
height hitherto attained, of which the density continually decreases in
the inverse ratio of the superincumbent weight. But, as I have before
observed, it is possible that this first stratum is surmounted by
several others consisting of very different fluids.
Our business, in this place, is to endeavour to determine, by
experiments, the nature of the elastic fluids which compose the inferior
stratum of air which we inhabit. Modern chemistry has made great
advances in this research; and it will appear by the following details
that the analysis of atmospherical air has been more rigorously
46