NOTE ON THE PRINCIPLE OF REGELATION, ETC. 65 
which were alone exposed, its substance having been torn through in 
the effort to separate the united plates by mechanical force.* The 
same effect took place in some experiments by Clement Desormes. 
I assume it to be highly probable that the process by which the 
two plates of glass become one, is, in reality, analogous to that of 
regelation in ice, and finally dependent on the same principles, 
whatever their true character may be conceived or shall ultimately 
be determined to be. To this it may be objected, however, that 
there is no evidence, in the case of the glass, of the previous lique- 
faction, or even approach to liquefaction, of the surfaces which 
become united so as entirely to disappear (or, more properly speaking, 
to be altogether obliterated), and that the phenomenon is referable 
simply to the homogeneous attraction of the molecules of one plate for 
those of the contiguous one, the evenness of the two polished sur- 
faces allowing them to be brought within a very minute distance of 
one another. But two remarkable facts greatly diminish the weight 
of this objection, if, indeed, they do not entirely remove it. First, 
unpolished plates of glass have no tendency to unite; the hard and 
compact siliceous film, to which Prof. Faraday, regarding glass “as 
a solution of different substances one in another,’ long ago referred 
its power of resisting agents generally, and which previously bound 
together the outer molecules of each plate, must be removed by 
grinding and polishing, so as to render the actual surfaces of contact 
those of portions of the glass, the chemical nature and condition of 
which are such as readily to admit of their rapid mutual action and 
union into one mass. Secondly,the polished plates sometimes have the 
forms and configurations of the surfaces of straw and other packing- 
materials impressed upon them (portions of straw, paper, &c., some- 
times adhering inseparably to the glass, after having been taken to 
hot climates),t in consequence of the soft nature of the substance 
exposed by the polishing, or of its nature being such as readily to 
soften by a temperature very much below that of the proper fusion, 
or even softening, of the glass in its integrity. The state of the in- 
terior portions of a plate of plate-glass appears, therefore, to be similar 
'* These and other facts of a similar nature I adduced as illustrative of the physical 
nature of glass, in lectures on that substance delivered before the Pharmaceutical Society of 
London in the year 1845. See Pharm. Journ. vol. v. (Oct. 1845) pp. 157-160. 
¢ Phil. Trans. 1830; Exp. Res. in Chem. and Phys. p. 282. 
t These particular facts were communicated to me by Mr. Tite, F.R.S., who had himself 
observed them. 
Vou. VI. E 
