of nature, admit
now of an easy explanation. For if the bowels of the earth are the grand
recess of these newly discovered inflammable bodies, whenever water
penetrates into them, combustions and explosions must take place; and it
is remarkable that the lava which is thrown out, is the very kind of
substance which might be expected to result from these combustions.

I must now take my leave of you; we have had a very long conversation
to-day, and I hope you will be able to recollect what you have learnt.
At our next interview we shall enter on a new subject.

END OF THE FIRST VOLUME.

Printed by A. Strahan,
Printers-Street, London.

* * * * *
* * * *

CONVERSATIONS
ON
CHEMISTRY;

In Which
The Elements Of That Science
Are
_Familiarly Explained_
And
Illustrated By Experiments.

IN TWO VOLUMES.

_The Fifth Edition, revised, corrected,_
_and considerably enlarged._

VOL. II.
ON COMPOUND BODIES.

_London:_
Printed For Longman, Hurst, Rees, Orme, and Brown,
Paternoster-Row.
1817.

CONVERSATION XIII.

ON THE ATTRACTION OF COMPOSITION.

MRS. B.

Having completed our examination of the simple or elementary bodies, we
are now to proceed to those of a compound nature; but before we enter on
this extensive subject, it will be necessary to make you acquainted with
the principal laws by which chemical combinations are governed.

You recollect, I hope, what we formerly said of the nature of the
attraction of composition, or chemical attraction, or affinity, as it is
also called?

EMILY.

Yes, I think perfectly; it is the attraction that subsists between
bodies of a different nature, which occasions them to combine and form a
compound, when they come in contact, and, according to Sir H. Davy's
opinion, this effect is produced by the attraction of the opposite
electricities, which prevail in bodies of different kinds.

MRS. B.

Very well; your definition comprehends the first law of chemical
attraction, which is, that _it takes place only between bodies of a
different nature_; as, for instance, between an acid and an alkali;
between oxygen and a metal, &c.

CAROLINE.

That we understand of course