26 CO. M. Wetherill on the Crystalline Nature of Glass. 
favorably disposed for the etching process. The result of this 
series of experiments seemed to throw some doubt. upon the 
“elevated” character of the acicular web of crystals; at least 
as much doubt as may arise from the difficulty of judging the 
question from the shadows. ‘The former conclusion was reached 
by a comparison of the shadows with those of a web of crystals 
of sublimed caffeine which were known to be in relief. If in 
intaglio, their depression is too slight to be able to form a judg- 
ment by rubbing the etching with vermilion powder. But 
the stars are known to be depressions, it may be that the scat- 
tered needles are of the same character 
In some examples, two rays of a star- shaped crystal were seen 
giving the form of a V, which in other cases was transformed 
base. The A-shaped Smee described upon a former page el 
same reagent 
Il of the specimens of glass submitted to the wees of hydro- 
fluoric acid yielded crystalline forms. ose of the window 
glass are similar in appearance to the crystals sited by Pe- 
louze by the slow cooling of the same kind of glass after it had 
been maintained for several hours at incipient fusion. Since in 
the experiments of this chemist no alteration of weight was 
observed and the normal character of the glass was restored by 
simply melting, it is probable that the crystals are of the same 
nature in both instances, It would appear from some of my ~ 
observations as if the erystals first formed during the refrigera- _ 
tion of the glass, were subsequently broken by the operations of 
pressing, rolling &ec., to which the material had been subjected. 
Doubtless additional interesting phenomena might be observed 
by a more extended study of different arated of glass under 
different conditions by the use of this 
ee penogons action of certain aatraals upon other sup 
ies, as the resins, &c. may demonstrate a crystal- 
toa racter in them. : 
From a more extended study of this interesting subject, results 
the most go apertens respecting the true nature of glass may be ~ 
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