d sulphuric acid; they become first
oxydated by decomposing part of the acid, and then dissolve in the other
part; but they do not sufficiently disoxygenate the decomposed part of
the acid to reconvert it into sulphur; it is only reduced to the state
of sulphurous acid, which, being volatilised by the heat, flies off in
form of sulphurous acid gas.

Silver, mercury, and all the other metals except iron and zinc, are
insoluble in diluted sulphuric acid, because they have not sufficient
affinity with oxygen to draw it off from its combination either with the
sulphur, the sulphurous acid, or the hydrogen; but iron and zinc, being
assisted by the action of the acid, decompose the water, and become
oxydated at its expence, without the help of heat.

TABLE _of the Combinations of the Sulphurous Acid with the Salifiable
Bases, in the order of affinity._

_Names of the Bases._ _Names of the Neutral Salts._

Barytes Sulphite of barytes.
Potash potash.
Soda soda.
Lime lime.
Magnesia magnesia.
Ammoniac ammoniac.
Argill argill.
Oxyd of zinc zinc.
iron iron.
manganese manganese.
cobalt cobalt.
nickel nickel.
lead lead.
tin tin.
copper copper.
bismuth bismuth.
antimony antimony.
arsenic arsenic.
mercury mercury.
silver silver.
gold gold.
platina platina.

_Note._--The only one of these salts known to the old chemists was the
sulphite of potash, under the name of _Stahl's sulphureous salt_. So
that, before our new nomenclature, these compounds must have been named
_Stahl's sulphureous salt_, having base of fixed vegetable alkali, and
so of the rest.

In this Table we have followed Bergman's order of affinity of the
sulphuric acid, which is the same in regard to the earths and alkalies,
but it is not certain if the order be the same for the metallic
oxyds.--A.

SECT. XV.--_Observations upon Sulphurous Acid, and its Combinations._

The sulphurous acid is formed by the u