Mr. Watt’s Observations 
292 
the only requisite for the formation of crystals.* The circum- 
stances I have detailed, appear to me an additional confirmation 
of this remark, and perhaps go still farther, by showing that 
even the fluidity (in the common sense of the word) of the 
suspending medium is not an indispensable condition. For it 
appears impossible to annex the idea of fluidity. to the union of 
the minute globules which form the jaspideous substance, still less 
to that substance when formed, and still less to those spheroids 
whose obstinate impenetrability is so strongly defined. And if, 
by any power of imagination, these can be supposed to be fluid 
at the time they retain this conformation, how can it be sup- 
posed that the compact hard tenacious stone into which they 
are changed could retain these characters in a fluid state? Yet 
the subsequent formation of crystals proves, that either all these 
contradictions must be, or that the particles of bodies apparently 
solid must be capable of some internal motion, enabling them 
to arrange themselves according to polarity, while they are solid 
and fixed, as far as they have reference to the ordinary cha- 
racters of fluidity. 
Instances even more remarkable have very long been known 
and authenticated, though perhaps they have not been generally 
regarded with the attention they deserve. Glass vessels are 
well known to be convertible into Reaumur’s porcelain, by the 
internal arrangement of their particles, without losing their ex- 
ternal form, and consequently at a temperature very much 
below that requisite for their fusion. The change of glass into 
* See a chemical Analysis of some Calamines, by James Smithson, Esq. Philoso- 
phical Transactions for 1803, page 27. See also Dolomieu, Journal des Mines. 
No. 22, page 53. 
