34 The Origin of the 



liquid state, and capable in some degree of pene- 

 trating and taking some partial impression from the 

 fibre of the wood which it consumed, as De la Beche 

 says is also the case with some lavas. 



We have already noted, but it may not be amiss 

 to repeat here, two particulars which seem to bear 

 upon the question of the igneous or aqueous origin 

 of the flint ; namely, first, the manifest blistering of 

 the exterior bark of the flint specimens of tree-roots 

 by the escape of the gases in burning, which would 

 not have occurred in aqueous infiltration ; and 

 secondly, the welding together of the contiguous sand 

 and pebbles in the instance of the specimen from the 

 Petrified Forest of Cairo. It may be added that in 

 some cases the chalk into which the flint has fallen 

 has been partially crystallized, apparently by contact 

 with the burning heat of the flint. A practical 

 geologist has even lately pointed out to me ironstone 

 which had apparently been partially fused by the 

 burning heat of flint which had fallen into it. 



In the preceding observations I have not touched 

 upon the subject of chalcedony, which is not con- 

 nected with flint except as being occasionally found 

 lining the interior of hollow nodules. If it be of 

 different formation, as it also differs in structure and 

 qualities, we are not now concerned with it. It is 

 found in rocks of igneous origin : sometimes in 

 stalactitic forms, sometimes reniform or botryoidal ; 

 but I am not aware that its stalactites show the 

 concentric rings which are exhibited by those that 

 are formed by aqueous filtration, as in the case of 



not aqueous rain, had been spoken of as accompanying the hail ; 

 and so in Psalm cv. 32, the literal rendering and order of the 

 Hebrew there being, " He gave for their showers hail, fire, flames 

 in their land." So also the Septuagint in that place. 



