without effervescence; and, in short, it is converted into a black oxyd,
precisely similar to that which has been burnt in oxygen gas.
In this experiment we have a true _oxydation_ of iron, by means of
water, exactly similar to that produced in air by the assistance of
heat. One hundred grains of water having been decomposed, 85 grs. of
oxygen have combined with the iron, so as to convert it into the state
of black oxyd, and 15 grs. of a peculiar inflammable gas are
disengaged: From all this it clearly follows, that water is composed of
oxygen combined with the base of an inflammable gas, in the respective
proportions of 85 parts, by weight of the former, to 15 parts of the
latter.
Thus water, besides the oxygen, which is one of its elements in common
with many other substances, contains another element as its constituent
base or radical, and for which we must find an appropriate term. None
that we could think of seemed better adapted than the word _hydrogen_,
which signifies the _generative principle of water_, from [Greek: ydor]
_aqua_, and [Greek: geinomas] _gignor_[17]. We call the combination of
this element with caloric _hydrogen gas_; and the term hydrogen
expresses the base of that gas, or the radical of water.
This experiment furnishes us with a new combustible body, or, in other
words, a body which has so much affinity with oxygen as to draw it from
its connection with caloric, and to decompose air or oxygen gas. This
combustible body has itself so great affinity with caloric, that, unless
when engaged in a combination with some other body, it always subsists
in the aeriform or gasseous state, in the usual temperature and pressure
of our atmosphere. In this state of gas it is about 1/13 of the weight
of an equal bulk of atmospheric air; it is not absorbed by water, though
it is capable of holding a small quantity of that fluid in solution, and
it is incapable of being used for respiration.
As the property this gas possesses, in common with all other combustible
bodies, is nothing more than the power of decomposing air, and carrying
off its oxygen from the caloric with which it was combined, it is easily
understood that it cannot burn, unless in contact with air or oxygen
gas. Hence, when we set fire to a bottle full of this gas, it burns
gently, first at the neck of the bottle, and then in the inside of it,
in proportion as the external air gets in: This combustion is slow and
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