on Basalt , &c. 303 
probability that new compounds may result, dissimilar to any 
substances we are acquainted with. It would appear, that the 
necessity of imagining an undiscovered stratum abounding in 
leucites, chrysolites, and augites, may be dispensed with ; and, 
as I have endeavoured to show the probability that the most 
infusible substances will not be the first to crystallize, the pene- 
tration of refractory leucites by fusible augites, will cease to be 
an argument against both being generated in the lava. I may 
also observe, that the same causes which vary the crystallized 
bodies resulting from igneous solution, must operate upon the 
unarranged basis; and that the same rock may be fused into 
lavas extremely dissimilar, as their varieties must depend on the 
degree of solution which the fusion has accomplished.* 
If the analogy attempted to be shown between the aqueous 
and igneous formation appear founded, the transition from glass 
to stone can no way affect the great question which has so long 
divided geologists, about the origin of basalt ; for, though it is 
synthetically demonstrated that basalt may be formed by fire, 
the converse of that proposition stands supported by strong ana- 
logical arguments, and its formation by water must be allowed 
to be at least equally possible. How far the probabilities derived 
from the examination of basaltic formations may influence the 
ultimate decision, is an enquiry in which I shall not now engage ; 
though I cannot avoid recalling to my mind, the numerous 
* The evidence of the generation of leucites in the lava which contains them, 
collected by Leopold de Buch, and Breislac, and finally acquiesced in by Dolo- 
mieu, appears so satisfactory, that it can hardly be deemed presumptuous to assume 
the point as determined. Neither de Buch nor Dolomieu have been able to con- 
vince themselves that the augites were also formed in the lava ; but I confess myself 
entirely unable to appreciate the cogency of their arguments, which seem annihilated 
by the admission they have made in favour of leucites, 
Rr 
MDCCC1V. 
