HEAD OF FLtNT. 197 



of an enamel, sufficiently transparent to allow the different 



shades of the silex, more or less gray or bluish, to appear 



through it in some places. 



Is this covering, for T do not think it can be termed a crust, * s tnis natur *l 

 ^ „ or artificial? 



the work 01 nature, or ox art r 



It is obvious, that we cannot refer to analysis, to solve this Obstac'es to 

 question; for thus the fragment must be destroyed, and lts analvsis - 

 even then we should not obtain a sufficient quantity of the 

 covering to afford unequivocal results. Nay, should they be 

 certain and easy, they could inform us of nothing more, 

 than we know already by its external characters of colour, 

 opacity.^ hardness, arid unalterability in acids, that its con- 

 stituent parts are the same as those of caicedony. 



The first idea that suggests itself on the inspection of this Apparently aa 

 head is, that the block of flint, after having been laboriously 

 cut on the wheel, in the same manner as gems, received a co- - 

 vering in the fire of the same nature as that applied on the 

 biscuit in making porcelain. Not only do the glassiness of 

 the enamel, and its thinness, appear to afford grounds for 

 this opinion ; but it is supported by comparing its shining 

 surface with the dullness of the white crust, on two frac- 

 tures occurring at the bottom of the left cheek, this crust 

 having been formed evidently since it was buried in the 

 earth. 



But a large and more recent fracture on the right side ex- But the flint 



poses the silex retaining all its ordinary characters ; and it is never been 

 x . . exposed to a 



well known, that this substance loses its colour and trans- strong heat. 



parency in a lire incapable of fusing even feldtspar. The 

 fragment I subjected to this trial was exposed to a heat of 

 13° of the pyrometer only, when it separated into several 

 pieces, and assumed the appearance of a biscuit to its inte- 

 rior parts. 



This no doubt has led to a more general adoption of the p l0 bably 

 opinion, that the caicedony covering the silex can have been therefore na- 

 deposited on it only -in the humid way, during its having been 

 in the ground. 



Before I embraced it, I thought it necessary to search 

 among collections of minerals of' the same kind, for indica- 

 tions, at least, o. the possibility of such .a covering being a 

 natural production. 



In 



