pour qu’il se puisse operer le rapprochement le plus exacte des parcelles ou molecules homogenees de nouveau corps qu’enfin les molecules les plus pures et les mieux affinees soyent reunies en forme liquide dans des cavites, et que par l’evaporation et separation de l’eau, ou elles nageoient, il s’en forme des crystaux n’aurons-nous pas une boule de silex, avec de crystaux de quartz dans ses creux interieurs.”

The supposed case is this; a calcareous body is to be metamorphosed into a siliceous nodule, having a cavity within it lined with quartz, crystals, etc.  M. de Carosi means to inform us how this may be done.  Now, as this process requires no other conditions than those that may be found upon the surface of this earth, the proper way to prove this hypothetical theory, would be to exhibit such a mineral body produced by those means.  But, even supposing that such a process were to be exhibited, still it would remain to be explained, how this process, which requires conditions certainly not be found at the bottom of the sea, could be accomplished in that place, where the strata of the earth had been deposited, accumulated, consolidated, and metamorphosed.

This mineral process, which has been now described, will no doubt revolt the opinions of many of our chemists as well as naturalists; and I should not have thought of transcribing it, but as an example of that inconclusive reasoning which prevails in mineralogical writings upon this subject.

But this is not all.  We have, upon this occasion, a most remarkable example of the fallaceous views that may be taken of things; and of the danger to science when men of sense and observation form suppositions for the explanation of appearances without that strict conformity with the principles of natural philosophy which is requited on all occasions.  Both M. de Carosi, and also M. Macquart[40], to whom our author communicated his ideas and proper specimens, assert, that from their accurate experience, they find calcedony growing daily, not only in the solid body of gypsum, etc. while in the mine, but also in the solid stone when taktn out of the mine, and preserved in their cabinet.

[Note 40:  Vid.  Essais de Mineralogie par M. Macquart.]

What answer can be made to this positive testimony of these gentlemen, by a person who has not seen any such a thing, and who has not the opportunity of examining the cases in which those naturalists may have perhaps been led into some delusion?  Were I however to conjecture upon a subject in which I have not any positive information, I should suppose that some part of the calcedony, like the oculus mundi when dipped in water, may be so transparent, while containing some portion of humidity, that it is not easily distinguishable from the gypsum in which it is concreted; but that in having the humidity evaporated, by being taken out of the mine and exposed to the dry air, those portions of calcedony, which did not before appear, may be perceived by becoming more opaque[41].