dreadfully suffocating smell.

MRS. B.

It is certainly extremely offensive; but by keeping the mouth shut, and
wetting the nostrils with liquid ammonia, in order to neutralize the
vapour as it reaches the nose, its prejudicial effects may be in some
degree prevented. At any rate, however, this mode of disinfection can
hardly be used in places that are inhabited. And as the vapour of nitric
acid, which is scarcely less efficacious for this purpose, is not at all
prejudicial, it is usually preferred on such occasions.

CAROLINE.

You have not told us yet what is Sir H. Davy's new opinion respecting
the nature of muriatic acid, to which you alluded a few minutes ago?

MRS. B.

True; I avoided noticing it then, because you could not have understood
it without some previous knowledge of the oxy-muriatic acid, which I
have but just introduced to your acquaintance.

Sir H. Davy's idea is that muriatic acid, instead of being a compound,
consisting of an unknown basis and oxygen, is formed by the union of
oxy-muriatic gas with hydrogen.

EMILY.

Have you not told us just now that oxy-muriatic gas was itself a
compound of muriatic acid and oxygen?

MRS. B.

Yes; but according to Sir H. Davy's hypothesis, oxy-muriatic gas is
considered as a simple body, which contains no oxygen--as a substance of
its own kind, which has a great analogy to oxygen in most of its
properties, though in others it differs entirely from it. --According to
this view of the subject, the name of _oxy-muriatic acid_ can no longer
be proper, and therefore Sir H. Davy has adopted that of _chlorine_, or
_chlorine gas_, a name which is simply expressive of its greenish
colour; and in compliance with that philosopher's theory, we have placed
chlorine in our table among the simple bodies.

CAROLINE.

But what was Sir H. Davy's reason for adopting an opinion so contrary to
that which had hitherto prevailed?

MRS. B.

There are many circumstances which are favourable to the new doctrine;
but the clearest and simplest fact in its support is, that if hydrogen
gas and oxy-muriatic gas be mixed together, both these gases disappear,
and muriatic acid gas is formed.

EMILY.

That seems to be a complete proof; is it not considered as perfectly
conclusive?

MRS. B.

Not so decisive as it appears at first sight; because it is argued by
those who still incline to the old doctrine, that muriatic acid gas,
however dry it may be, always contains a c