d, by uniting with caloric, assumes the form of hydrogen gas.
Red hot iron is usually employed for this purpose: The iron, during the
process, becomes oxydated, and is changed into a substance resembling
the iron ore from the island of Elba. In this state of oxyd it is much
less attractible by the magnet, and dissolves in acids without
effervescence.

Charcoal, in a red heat, has the same power of decomposing water, by
attracting the oxygen from its combination with hydrogen. In this
process carbonic acid gas is formed, and mixes with the hydrogen gas,
but is easily separated by means of water or alkalies, which absorb the
carbonic acid, and leave the hydrogen gas pure. We may likewise obtain
hydrogen gas by dissolving iron or zinc in dilute sulphuric acid. These
two metals decompose water very slowly, and with great difficulty, when
alone, but do it with great ease and rapidity when assisted by sulphuric
acid; the hydrogen unites with caloric during the process, and is
disengaged in form of hydrogen gas, while the oxygen of the water unites
with the metal in the form of oxyd, which is immediately dissolved in
the acid, forming a sulphat of iron or of zinc.

Some very distinguished chemists consider hydrogen as the _phlogiston_
of Stahl; and as that celebrated chemist admitted the existence of
phlogiston in sulphur, charcoal, metals, &c. they are of course obliged
to suppose that hydrogen exists in all these substances, though they
cannot prove their supposition; even if they could, it would not avail
much, since this disengagement of hydrogen is quite insufficient to
explain the phenomena of calcination and combustion. We must always
recur to the examination of this question, "Are the heat and light,
which are disengaged during the different species of combustion,
furnished by the burning body, or by the oxygen which combines in all
these operations?" And certainly the supposition of hydrogen being
disengaged throws no light whatever upon this question. Besides, it
belongs to those who make suppositions to prove them; and, doubtless, a
doctrine which without any supposition explains the phenomena as well,
and as naturally, as theirs does by supposition, has at least the
advantage of greater simplicity[40].

TABLE _of the Binary Combinations of Sulphur with Simple Substances._

_Simple_ _Resulting Compounds._
_Substances._ _New Nomenclature._ _Old Nomenclature._

Caloric Sulphuric ga