Full text: Vol. II (2)

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
	        
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