NOTE ON THE PRINCIPLE OF REGELATION, ETC. 71 
IT now venture to submit the inquiry, Does this apparent deficiency 
in our knowledge exist because—to use language recently introduced 
into physical science—the homologue of the glassy state of water is 
not what we ordinarily term solid—because the state of water cooled 
below 32° but still liquid is in fact the state which corresponds to 
the vitreous condition of other bodies, and to the physical nature of 
perfect ordinary glass? Is the one simply a case of potential soli- 
dity, and the other of the confluent or equivalent state of arrested 
liquidity ? 
Jt may be said that the homology which is here endeavoured to be 
established between liquid water below 32° and glass, is a forced one. 
That, in relation to each other, these are extreme cases is perfectly 
true ; but intermediate terms of the series are not wanting, and some 
of them are supplied by sulphur and phosphorus, and in a remark- 
able manner by selenium. All these bodies, when melted, may be 
cooled many degrees below their freezing-points and yet remain fluid. 
Sulphur presents, in its viscid form, an approach to the glassy con- 
dition ; but it may be obtained in the crystallineform on passing from 
a state of fusion, and when cooled below freezing, instantaneously 
crystallizes, like water, by mechanical disturbance. 
In phosphorus also there is the viscid state ; and when cooling after 
fusion, it passes gradually, like glass, from the liquid to the solid con- 
dition without crystallizing, though crystals are deposited from some 
of its solutions. Selenium presents a state resembling the viscid 
state of the preceding substances ; but when melted, and left to cool 
remains fluid below its melting-yoint, and solidifies very gradually in 
its amorphous state (in which it has some of the characteristic pro- 
perties of glass), and a thermometer immersed in it during the cool- 
ing does not remain stationary at any point, or indicate any tempe- 
rature at which heat is evolved by molecular change in the substance, 
—as if the selenium passed continuously from the liquid glassy state 
to that of solid glass. At ordinary temperatures it retains this con- 
dition for a long time—as common glass does at higher, and as water 
and sulphur will at lower temperatures; but when heated again, 
between a certain temperature and its melting-point it becomes cry- 
Mr. Drummoné (Phil. Mag., August 1859, S. 4. vol. xviii. pp. 102—103) do not involve the 
physical condition of those bodies, but relate merely to the resemblance of one crystallized 
substance (ice) to another (Reaumur’s porcelain), and of both toa third body (bottle- and 
window-glass), which, from its optical characters, is inferred—I thing inconsequentially— 
to haye assumed a state preparatory to crystallization. 
