"
So accurate an observer, and so complete a naturalist, must have
observed how the extraneous substance had been introduced into this
cavity, had they not been formed together the cavity and the calcareous
crystals. That M. de Saussure perceived no means for that introduction,
will appear from what immediately follows in that paragraph. "Ces rocs
auroient-ils ete detruits, ou bien ce spath n'est il que le produit
d'une secretion des parties calcaires que l'on fait etres dispersees
entre les divers elemens du granit?"
Had M. de Saussure allowed himself to suppose all those substances in
fusion, of which there cannot be a doubt, he would soon have resolved
both this difficulty, and also that of finding molybdena crystallized
along with feld-spar, in a cavity of this kind. sec. 718.
To this argument, taken from the close cavities in our agates, I am now
to add another demonstration. It is the case of the calcedony agate,
containing a body of calcareous spar; here it is to be shown, that,
while the calcareous body was altogether inclosed within the calcedony
nodular body, these two substances had been perfectly soft, and had
mutually affected each others shape, in concreting from a fluid state.
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