ON QUARTZ AND CRYSTAL.
201
low the ſurface of the earth, enables it to dissolve quartz, and to trans
port it and to crystallize it, which matter cannot probably remain
combined with water when it comes to the furface and is exposed to
light. Bergmann was deceived when he imagined fixed air combin
ed with water to be a folvent of quartz: The experiments of other
chémiſts have not supported this opinion. I have not been able to
make it dissolve silica, even when fresh precipitated from liquor silicum.
Siliceous crystals are often formed in nature on the surface of calcare
ous ones, without the ſmalleſt appearance of difsolution or corrosion
in theſe laſt, which would certainly happen were the solvent of the
siliceous matter carbonic acid water. Mr. Morveau also mistakes
this water. (Encyclopedie Metbodique). For, in an experiment in which
siliceous crystals were formed by ſhutting up in a vessel aërated water
and siliceous earth, there was iron also, which became corroded and
ruſted, and the crystals were found among the ruſt of the iron. He
had four glasses, containing aërated water and filex. Into one was
put ſilex; into another limeſtone; into a third, argilla; and into the
fourth, iron. After nine months, no change appeared, except in
the laſt, in which both the pieces of quartz and the iron were evident
ly corroded, and ſmall crystals found among the ruſt of the iron. Do
lomieu therefore concludes that the hydrogen, separated by the action
of the difsolving iron on a small part of the water, produced, in con
junction with the reſt of the water, a solvent which acted on the
quartz. Dolomieu learned, however, by experiments, that iron has
no effect on the liquor silicum, or the liquor on the iron. A bit of
polished iron preserves its brightness unimpaired in this fluid. That
the solvent of silica in nature is an inflammable substance, is also ren
dered probable by the dusky colour of some crystals and of flint,
which dark or duſky appearance is dissipated by fire. He adds one
more argument to support his opinion of the compounded nature of
quartz and crystal. This is drawn from its inactivity, or want of at
traction for most other substances.
VoL. II.
Cc