It is not a mere resemblance that should homologate
different things; there should be a specific character in every thing
that is to be generalised. It will be our business to show that, in the
false stalactites, there is not the distinctive character of those water
formed bodies to be found.
In the formation of stalactical concretions, besides the incrustation as
well as crystallization of the stony substance from the aqueous vehicle
by which it had been carried in the dissolved state, we have the other
necessary accompanyments of the operation, or collateral circumstances
of the case. Such, for example, is that tubular construction of the
stalactite, first formed by the concretion of the calcareous substance
upon the outside of the pendant gut of water exposed to the evaporation
of the atmosphere; we then see the gradual filling up of that pervious
tube through which the petrifying water had passed for a certain time;
and, lastly, we see the continual accretion which this conducting body
had received from the water running successively over every part of
it. But among the infinite number of siliceous concretions and
crystallizations, as well as those of an almost indefinite variety of
other substances, all of which are attributed to solution, there is not
the least vestige of any collateral operation, by which the nature of
that concretion might be ascertained in the same manner.
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