70 NOTE ON THE PRINCIPLE OF REGELATION, ETC. 
even after the glass has become solid as such, by the operation of a 
principle in this view analogous to regelation, until the entire mass 
has become crystalline.* 
3. No crystalline body has been longer or more extensively subject 
to human observation, than crystallized water, or ice. Its natural 
history and properties, as science has advanced, have been investi- 
gated with increasing generality and precision ; and they have finally 
become objects of that systematic and exact research which charaec- 
terizes the present era of physical inquiry,—as is evinced by the dis- 
cussion on regelation, to which these notes are intended to be sup- 
plementary. A most remarkable deficiency, however, still remains, 
apparently, in our knowledge of this substance:—Water in the 
vitreous condition—Ice-glass—has never been observed. While 
we know the antithetical vitreous state of so many different cry- 
stallized substances—minerals produced by heat, salts deposited from 
aqueous solution, neutral bodies of organic origin—and have great 
reason to believe that that antithetical condition to crystallization 
is universal, we have no knowledge of it in relation to water or ice. 
My own attention has been awake to the subject, without success, 
for many years. It would seem to be scarcely within the bounds of 
possibility that the glassy state of water, if possessing what we term 
solidity, should not, ere now, either have been observed in nature, or 
have occurred and been recognized in experimental research.+ 
» If weshould prefer to adopt Mr. Maskelyne’s suggestion in a formal manner, and 
regard glass as resembling a solution about to crystallize, its analogue, agreeably to the 
preceeding views, will be a saturated solution of a salt in hot water, allowed to cool undis- 
turbed, and remaining fluid, until its cohesion is affected, when its temperature rises, and 
the salt crystallizes. Specimens of glassare common which have the aspect and distribution 
of parts of a crystallized salt in the mother-liquor ; opaque crystallized spherules appearing 
in the midst of a transparent mass. Tothese correspond, among natural glasses, pifchstone 
and many examples of porphyritic obsidian, consisting of a vitreous base in which crystals 
have been formed and are imbedded. 
But at the same time the view I have taken of the subject, and Mr. Maskelyne’s may be 
equally tenable; for the state of water remaining liquid at temperatures below 32°, and 
that of saline solutions remaining uncrystallized at temperatures below those of solidification, 
are evidently closely analogous. 
Should I return to this subject, I shall refer to my friend Mr. Sorby’s observations on 
the nature of glass, which i had not read when these notes were communicated to the 
Royal Society, but which are in entire agreement with the views I have snggested.—See 
Quart. Journ. of Geol. Soe. vol. xiv. p. 465. , 
t+ The crushed fragments of the ball of ice cooled in carbonic acid and ether, in Prof. 
Tyndall’s experiment already mentioned, which “remained white and opaque as those of 
crushed glass,” were still, he informs me, perfectly crystalline, resembling fragments of 
quartz. 
The “points of analogy between the molecular structure of ice and glass” noticed by 
