Prof. Berzelius’s Letter io the Editor. O77 
me that this 
may be the same mineral as ‘the Kiliite, Creadead Vol, 
I. p 
‘ir. Walmstedi, professor of chemistry at Upsal, has per- 
formed a series of researches upon prehnite, of which, as it is 
in Latin, | take the liberty to send you a copy. 
(2.) Fluoric Acid—Reduction of silex, giving salicium ; and Z 
Ps 
of zircon, giving zireonium.—I have made a considerably ex- 
tended research upon fluoric acid, which is nevertheless far 
from being finishe 
By way of digression, [ have discovered the method of 
reducing silex, so as to obtain posi. the properties of 
which are extremely curious. The following is them 
near to redness to expel the moisture. Put this salt, with 
potassium, into a glass ae closed at one end, and heat it by 
means of alamp. The potassium gives a dull sound, and 
the dilex 1 is reduced. The ifrevativas) brown mass requires 
to ee washed a long time, in order to remove the undecom- 
posed portion. We then have the silicium remaining upon 
the filter, in the form of a brownish powder. When it is 
dried, it can be made to burn by heating it red hot; but if it 
ed in 
is gently platina crucible, half covered, and if the 
silicium tak overed entirely, it contracts by little and 
little, and nco e. Before it is thus heated, 
¢ acid dissolves it with the extrication of hydro- 
gen, after which it acts only by extracting a part of the silex, 
* An abstract of the results of these researches is subjoined. ie 
Vou. IX. No. 2. 48 
