342 On a sculptured Head in Flint, 



of an enamel sufficiently translucid to admit of the different 

 gray or blue shades of the silex being seen through it. 



Is this covering (for I do not think I can give it the name 

 of incrustation) a work of nature or a production of art? 



One would think that analysis mic;ht be resorted to in 

 order to resolve this question ; but the article would be en- 

 tirely destroyed, and even by destroying; it we could not get 

 enough of this covering matter from which to obtain un- 

 equivocal results, and after all, nothing mof»e might be 

 learnt than is alreadv known from its external characters of 

 colour, opacity, hardness, and inalterability in the acids ; 

 z. e. that its constituent parts are the same as those of chal- 

 cedony. 



The first idea presented by the inspection of this head is, 

 that the block of silex, after having been laboriously sculp- 

 tured with a drill, like other hard stones, had received a 

 covering in the fire of the nature of that applied to the bis- 

 cuit porcelain. It was not only the gloss of its enamel, and 

 its thinness, that seemed to found this opinion, it was still 

 more confirmed by the comparison of its lustre with the 

 roughness of the white crust of the two fractures at the bot- 

 tom of the left cheek, a crust evidently formed since its being 

 deposited in the ground. 



But a large fracture, more recent, discovers the silex pre- 

 served with all its ordinary characters ; and we know that 

 this substance loses its colour and transparence in a fire so 

 low as to be incapable of fusing feldspar. The piece which 

 underwent this experiment was only exposed to a heat of 

 13 pyrometric degrees ; it was divided into several fragments, 

 and it assumed the appearance of a biscuit in the interior. 



This certainly strengthens the idea, that the chalcedony 

 which covers this silex could only have been placed there by 

 the humid way, while it was in the ground. 



Before adopting it, I thought proper to inquire among the 

 collections of minerals of this kind for indications, at least, 

 of the possibility of the natural production of a similar co- 

 vering. 



Flints are generally seen incrusted ralher than co- 

 vered 



