carbonic acid amounts, in the aggregate, to an
immense total. There is more than enough
carbon in the atmosphere to replace all the coal
that has been burnt since coal was discovered,
besides supplying all the charcoal contained
in every vegetable all over the world. Air
also contains the vapour of water. If a cold
and bright body, say a silver vase, is
suddenly brought into warm air, you will very
shortly see its surface dimmed by a coating
of dew.

For our knowledge of the composition of air
we are indebted to Lavoisier, whose experiments
on this very body led him to the theory which
bears his name, and which is the foundation of
modern chemistry. That oxygen and azote
make air, is thus demonstrated. Put mercury
under a bell-glass filled with air, and then raise
the mercury to a high temperature, but lower
than its boiling-point. If this temperature be
maintained for several days, the volume of air
in the bell-glass will be found to diminish
gradually, and at the same time there will be
formed on the surface of the mercury little red
scales, whose quantity will go on increasing.
What takes place in this experiment? The
reduced volume of air indicates an absorption,
and the formation of a new body on the
mercury suggests that the metal has appropriated
to itself the portion of air which has
disappeared. In fact, if the scales are collected and
exposed to strong heat, they are transformed
into mercury, after disengaging a gas which
is found to be oxygen. Oxygen, therefore,
exists in the air; its combination with the
mercury gave rise, on the surface of the metal,
to the body which is known as oxide of
mercury.

By prolonging the operation for a sufficient
length of time, a point is reached when there is
no further diminution of air in the bell-glass,
nor of scales in the mercurial bath; the cause
of which is, that all the oxygen contained in
the air has been absorbed by the metal.
Nevertheless, the air has not entirely disappeared.
There remains a gaseous residue under the bell-
glass; and that residue is composed solely of
azote. Air, therefore, is composed of oxygen
and azote. If it contain any other gas in very
small quantity, its presence is not betrayed in
consequence of the trifling volume of the air
experimented on.

The reader is reminded, only by way of
remembrancer, that plants, under the stimulus of
sunlight, take in and solidify carbonic acid, and
give out oxygen. The leaves of the forest, the
lichen on the rock, are strained out and stolen
from the air. Air has such influence on
vegetation, that there are plants which live and
thrive with no other nourishment than air and
the moisture it contains. Vegetation has the
property of restoring to the atmosphere the
corrupted, mephitic, and often mortal air in
which vegetables are capable of living. By
giving out oxygen and absorbing carbonic acid,
plants render air salubrious to be breathed by
animals. By an admirable reciprocity, the plant
grows and flourishes on what the animal rejects;
and what the plant exhales, gives life to the
animal.

REMINISCENCES OF BROGG.

IN FOUR CHAPTERS. CHAPTER TV.

AND now, the first introduction to Mr. Brogg
over, I found myself rapidly becoming friendly
with the revered gentleman. I was a great deal
with him, both at our club-room and also at his
own house. It was a happy time—perhaps
it was too happy to continue very long. I
saw, and did not like, an occasional tendency
to absence of mind and uneasy reflection in my
friend. There appeared to be seasons when he
was dissatisfied with his life, with his career, with
himself. It was only occasionally, however, as I
have said, that he fell into this condition, and in
the intervals between such attacks we were very
happy and comfortable.

A friend of ours—no other, indeed, than the
immortal Grampus—was engaged in a lawsuit
against one of his neighbours, in re, the
barking of a dog, which animal the said neighbour
kept tied up in his back garden; and it
appeared that this dog was so fond of the sound
of his own voice, that neither by day nor by
night did he cease to give tongue, barking at
all hours, and under all circumstances.

Now this dog-dispute, after being the motive
of a long correspondence, beginning very politely
and ending very savagely, became at last a
matter for the lawyers, who, having got hold of it,
determined to try the merits of the case before
twelve English tradesmen of more than average
stupidity. To the individual who kept the dog
this lawsuit was simply a boon. He was a
retired tradesman, with plenty of money and
nothing to do, and finding inexpressible pleasure
in making use of such expressions as "My
solicitor will wait on you," or "You will hear
from my solicitor," with the like imposing
and alarming phrases. I think, moreover, that
the "other party," namely, Grampus himself, also
took pleasure in the thought that he was
engaged in a lawsuit, talking of it freely wherever
he went.

It had been suggested to Grampus by his
lawyer that he should bring forward some
gentleman deeply versed in intellectual matters,
some person of high genius, in fact, to bear
witness as to the detrimental influence on mental
labour which such a noise as that of which
Grampus complained might be expected to
exercise; to prove, in short, that the nuisance
was a nuisance, calculated to interfere with the
artist's professional pursuits, and so, to some
considerable extent, affect his pecuniary
resources by hindering him in the exercise and
practice of his profession. Of course Grampus
was not long in perceiving that this was a case
in which he must seek the assistance of our
illustrious friend, nor was he slow to promise
that assistance as quickly as it was asked. "If