PROPERTIES OF THESE SALTS.
449
of potaſh or of soda. One part of this salt contains all the redundant
oxygen that is furniſhed by six of oxy-muriatic acid. I may remark
that the nitroſe acid, in its union with alkali, exhibits phenomena
pretty similar. We obtain a true nitre, and a nitrous gas.
The union of the ingredients of this oxy-muriat seems very flight.
Exposition to the air ſeems to decompose the acid : For in a few days,
or even hours, the falt changes to the ordinary salt of Sylvius. This
decomposition happens more speedily in a watery solution of the ſalt;
and we ſee a continual simmering on its surface, by the escape of mi
nute bubbles of elastic matter. This is increased by exposure to the rays
of the sun so as to be like an effervescence. This is vital air, of the purest
kind. It would ſeem that the cauſtic alkali acts too powerfully on the baſis
of the ordinary muriatic acid, and thus diminishes its attraction for the
oxygen ; or the oxygen exists in it, perhaps, in a semi-elastic state.
Mr. Berthollet also thinks that the vast abundance of water necessary
for absorbing this gas prevents a closer union of the acid and alkali.
He found that the combination could not be effected unless the solu
tion of the alkaline falt be extremely diluted. If this liquor be eva
porated, preserving it at the same time from the action of light, or the
naked fire, it undergoes, at a particular period of the evaporation, a sud
den change, by which the above salt is formed ; and that after this,
neither the liquor, nor any of the salts which it affords by evapora
tion, are possessed of the peculiar powers of the oxy-muriats.
Mr. Scheele discovered in this oxygenated acid another most re
markable property, namely, a power to deſtroy all vegetable and ani
mal colours, and even those which are most permanent, prepared for
the purposes of dying. It whitened or bleached vegetable substances
in a surprising manner. Mr. Berthollet first thought of applying it to
this use, and found that bees wax, brown linen yarn, and cloth, are
bleached by it in a few hours or minutes, as effectually, and with as
much safety to the staple of the goods, as if they had been exposed to
the sun and air, with that intention, for as many weeks.
VOL. II.
3 L