MRS. B.
The acid exists naturally in a gaseous state, and is here so strongly concentrated in water, that it is constantly escaping.
Here is another bottle of nitrous acid, which, you see, is of an orange red; this acid is weaker, the nitrogen being combined with a smaller quantity of oxygen; and with a still less proportion of oxygen it is an olive-green colour, as it appears in this third bottle. In short, the weaker the acid, the deeper is its colour.
Nitrous acid acts still more powerfully on some inflammable substances than the nitric.
EMILY.
I am surprised at that, as it contains less oxygen.
MRS. B.
But, on the other hand, it parts with its oxygen much more readily: you may recollect that we once inflamed oil with this acid.
The next combinations of nitrogen and oxygen form only oxyds of nitrogen, the first of which is commonly called nitrous air; or more properly nitric oxyd gas. This may be obtained from nitric acid, by exposing the latter to the action of metals, as in dissolving them it does not yield the whole of its oxygen, but retains a portion of this principle sufficient to convert it into this peculiar gas, a specimen of which I have prepared, and preserved within this inverted glass bell.
EMILY.