on Basalt, &c. 
297 
that, consequently, the same rock may become the parent of 
very diversified offspring. These will however retain some 
traces of their origin ; for, as there can be no fusion of a com- 
pound body imagined, in which the mutual action of the compo- 
nents will not decompose some portion, there can be no solution 
supposed so perfect that every molecule shall be destroyed. In 
the first case, there will exist the germs of a new composition ; 
and, in the second, there will remain the relics of the old. 
If these observations are correct, considerable utility seems 
derivable from them,, in the explanation of some geological 
problems. It will appear, that they strikingly illustrate the ana- 
logy which exists between the aqueous and igneous formations, 
and show that precisely the same order and kind of arrangement 
is followed, in the generation of stony masses from water as 
from fire ; for, the change of structure, which I have observed 
to be the most inexplicable part of the process by which glass 
passes into stone, is almost exactly imitated in the formation of 
calcareous stalactites. Successive depositions of calcareous car- 
bonate, form a stalactite which at first is fibrous. A continuance 
of the process causes the fibrous structure to disappear, and the 
stalactite becomes irregularly spathose. The irregularities then 
vanish, and it becomes perfect calcareous spar, divisible into large 
rhomboids, with the form peculiar to that mineral ; and all the 
gradations may be found in the same specimen. Nor is this 
change confined to a few solitary specimens ; for, a considerable 
extent of coast near Sunderland, is formed of a limestone composed 
of radiated spheroids, from half an inch to three inches diameter, 
imperfectly united.; When one of these spheroids attains some- 
thing more than the usual magnitude, it becomes compact in 
the heart ; and it is not unusual to discover portions of the rock, 
Qq 2 
