C. M. Wetherill on the Crystalline Nature of Glass. 17 
case. By an examination of the literature of the subject it was 
ascertained that Leydolt (Wiener Acad. Bericht, viii, 261) had 
made this interesting and important discovery. I have been in- 
clined to publish my results because Leydolt’s observations do 
ot appear to have received the attention which they merit; be- 
cause my manner of applying the acid is different; and because 
crystals were observed of form differing from those described in 
Leydolt’s paper. 
In addition to these reasons, his discovery may appear to need 
a certain confirmation, since Daubrée has asserted (Comptes 
Rend., xlv, 792) that the crystalline phenomena are due not to 
the glass, but to the deposition of crystals of fluosilicid of potas- 
sium, &., which retard the corrosive action by protecting the 
glass under them. In the following experiments with as pro- 
longed a microscopic observation as the object-glass could be 
trusted to the corrosive fumes, the result of the reaction of a 
drop of the acid upon the glass appeared to be amorphous. In 
an experiment in which a watch glass was exposed, with the 
convex surface downward, as a cover to a platinum crucible 
containing hydrofluoric acid; a lapse of twelve hours effected a 
deep corrosion. This was most extensive at the lowest point of 
the glass where a large drop of liquid was adhering. The solid 
products of the reaction had settled to the inferior portion of 
the drop, and some of them had fallen with previous drops into 
the crucible. A microscopic examination of the glass demon- 
Strated the presence of etched crystals, which could not, under 
the circumstances, have resulted from a protecting effect of crys- 
tals of fluosilicid. ; : e 
Frankenheim (Jr. pr. Ch., liv, 480) maintains that solid bodies 
generated from a liquid are alwayscrystalline, although the crys- 
may be too minute to be perceptible by our present instru- 
ments. His arguments, in the eases of glass, resins and the like, 
are @ priori, being based upon the analogies proceeding from a 
Study of the general properties of matter. They render the erys- 
talline character of glass very probable. 
This chemist places the glasses, resins, and fats in the same 
pr ry in their relations to crystallization. In the transition 
Place the angles are rounded by the cohesion of the liquid por- _ 
tions and the adhesion of these to the parts not yeewsalse elted. | 
ligher temperature, the liquid portion constitutes the mass of 
the body, but in it are suspended innumerable solid parti 
Aw. Jou. Sct.—Szconp Serres, Vor. XLI, No. 121.—Jan., 1866. 
, : 3 a ee 
