on Basalt, See. 
2 87 
in their change from a fluid to a solid state. It is reasonable to 
suppose, that heat may also be emitted in those changes of 
arrangement which affect the internal texture of a body, after it 
has attained an apparently solid state. That a succession of 
such changes does actually take place, appears to me demon- 
strated by the appearances I have described, and by the increase 
of specific gravity, which seems to keep pace with the internal 
changes of the substance. It would appear, that these changes 
are caused by a gradual diminution of temperature, which per- 
mits certain laws to induce peculiar arrangements among the 
particles of the glass. When several of these particles enter into 
this new bond of association, they must form a minute point, 
from which heat must issue in every direction. That heat will 
gradually propagate itself, till the temperature of the glass is 
equalized ; and then the recurrence of the circumstances which 
induced the first particles to arrange, will cause other particles 
to arrange also, which the attraction of aggregation will dispose 
round the point first formed. A second emission of heat in 
every direction will take place; the temperature will again be 
equalized ; and again another concentric coat of arranged particles 
will apply itself to the little globule. But, at the time when the 
central point of this globule was formed, the equality of tem- 
perature, in the mass of glass, would probably cause a number 
of similar points to be generated. The formation of each must 
proceed in a similar manner to what I have described, till their 
surfaces touch, and all the glass be converted into the same 
substance. 
These globules are therefore formed of concentric coats, but 
they are also radiated. Every one must have remarked the 
connexion that almost uniformly exists, between the radiated 
MDCCCIVc P p 
