114 



EECEEATIVE SCIENCE. 



pressiveness — how came they to lie bedded 

 in a mass so soft as chalk P the synonyme 

 for hardness enclosed in that for softness? 

 Philosophers cannot answer us unhesitatingly, 

 they can only conjecture. A common flint, 

 the refuse of our shores, the vilest material 

 of rough buildings, is, after all the progress 

 of science, still a standing mystery. 



A few points are, however, well ascer- 

 tained, and they are these : All these flints 

 were once in a state of fluidity. This is 

 proved by the fact that they contain in, or 

 fastened upon, their own substance numerous 

 petrified remains of sponges and animals, 

 which we shall presently describe. These 

 could not have become imbedded in the sub- 

 stance of the flint, and surrounded by it, un- 

 less the flint had once been fluid or semi-fluid. 

 ' Plint, also, as we now find it, or any siliceous 

 substance of a similar character, can be re- 

 duced again to fluid, or, as it is said, rendered 

 soluble, when subjected to the action of 

 caustic alkali (soda or potash) at a high tem- 

 perature, in a steam-boUer or in chambers 

 communicating with boilers. It readily fuses 

 in a vapour heated a little above that of fused 

 cast-iron. What is called E.ansome's arti- 

 ficial stone is manufactured by processes of 

 this kind. Chemists have discovered that 

 flint, or silex, to use the technical name, is 

 simply a compound of oxygen with a peculiar 

 base (silicon). Silex is one of the simple 

 materials entering into the composition of 

 many rocks and strata, and that in so large 

 a proportion that it is computed to form, 

 either in a fluid or combined state, nearly 

 one-half of the solid crust of the globe. 



A remarkable present production of flint 

 is now taking place in the siliceous deposits 

 formed by the celebrated geysers, or inter- 

 mittent boiling fountains, in Iceland, and on 

 a still grander scale in New Zealand, where, 

 ■from the crater of the volcanic mountain of 

 Tongariro, upwards of 6200 feet above the 

 level of the sea, jets of vapour and streams 

 of boiling water highly charged with silex 



are continually spouting forth. After dash- 

 ing down the sides of the volcano in cas- 

 cades and torrents, they empty themselves 

 into the lakes at the base. As the tempera- 

 ture of the water diminishes, a siliceous sinter 

 is deposited in vast sheets, and in incrusta- 

 tions of flint which are thrown down upon the 

 extraneous substances lying in the course of 

 these thermal or warm waters. Further, 

 silex is actually precipitated by the boiling 

 waters in the form of stalagmitic concretions, 

 and in nodules resembling in colour and 

 solidity the flints of the English chalk. This 

 has been witnessed and reported by Dr. Dief- 

 fenbach in his work on New Zealand. 



The most stupendous of the boiling pools 

 whichhe noticed is partly surrounded byacliff 

 sixty feet high, which is oxydized, corroded, 

 and undermined from the effects of the heated 

 vapours which are continually issuing forth in 

 jets. At the base of this cliff" the pond is con- 

 stantly boiling with a white foam, and throw- 

 ing up fountains eight or ten feet high with 

 great noise and violence. The generally in- 

 soluble silex is here held in solution by the 

 alkaline elements and very high temperature 

 of the water. In another spot is seen a deep 

 lake of a blue colour, surrounded by verdant 

 hills, and in the lake are several islets, on all 

 of which steam issues from a hundred open- 

 ings between the green foliage without im- 

 pairing its freshness. On the opposite side is 

 a broad flight of steps, of the colour and aspect 

 of white marble, with a rosy tint from silice- 

 ous incrustation, over which flows a cascade 

 of boiling water into the lake. 



On a small scale, Mr. Jeffreys has per- 

 formed the same operation as that we have 

 just described as in actual occurrence in New 

 Zealand. That gentleman determined, by ex- 

 periment, that silex is soluble in water highly 

 heated, without the presence of alkalies or 

 other chemical agents. 



There can now be no difficulty in conceiv- 

 ing that silex was largely held in solution in 

 the ancient chalk ocean, but there is considef- 



