344 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [April 23, 



printed by me in 1824 have been put forward, and have attained 

 extensive adhesion among continental geologists. 



M. Delesse has proved by experiment the solubility of the silex of 

 rocks in heated water containing either of the mineral alkalies. And, 

 indeed, the manufacture of artificial stone is now carried on in this 

 country (Messrs. Ransom's process) by saturating loose sand with 

 an artificial hydrate of silica. Huge blocks of flint, I understand, 

 are thrown into the hot alkaline water, and melt down like so much 

 sugar. 



Again, the experiments of Boutigny have shown that water at a 

 white heat remains unvaporized, in the form of spheroidal globules, 

 in which form it is obvious how readily it would communicate 

 mobility to the solid particles among which it was entangled ; and 

 how (according to these experiments) it might flash into bubbles of 

 vapour on the reduction of its temperature by exposure to the air. 



M. Deville, in his recent observations on the vapours disengaged 

 from Vesuvius since the eruption of May in last year (for the perusal 

 of which I am indebted to the kindness of my friend Dr. Daubeny), 

 arrived at the conclusion, to use his own words, that "water in the 

 proportion occasionally of 999 per mille must have formed an integral 

 part of the Vesuvian lava at the moment of its emission ; and con- 

 sequently, that in the interior of the incandescent lava there is such 

 an arrangement of molecules, as to permit the gaseous and volatile 

 matters to remain there imprisoned, until in the progress of cooling 

 and consolidation, they evolve themselves." 



Above all, M. Scheerer, of Christiania, the eminent Norwegian 

 geologist, who is better acquainted perhaps than any other with the 

 granites of that country, published in 1847 a theory, which, he says, 

 his observations had suggested to him in 1833, on the production of 

 granite, entirely identical with that which I had ventured to suggest 

 in 1824-25. I take the following account of it from the paper read 

 before the Geological Society of France in 1847, and published in 

 the fourth volume of the Bulletin de la Soc. Geol., p. 468. 



M. Scheerer attributes what he calls the "plasticity" of granite 

 when protruded on or towards the surface of the earth (a condition 

 evidenced by the veins it throws into the fissures of neighbouring 

 rocks) to the combined action of water and heat. He describes the 

 water as " intercalated between the solid atoms of the crystalline and 

 other constituent minerals, endeavouring to escape by its tendency to 

 vaporization, and consequent elasticity, but unable to do so owing to 

 the pressure to which the enclosing mass is subject." He considers 

 the water so contained in granite to be "primitive," that is, one of 

 the original bases of the rock, and not the result of infiltration. He 

 attributes to it the solution of the quartz, aided by the alkali, and the 

 consequent moulding of this mineral on the felspar-crystals. He 

 even goes the length of styling the condition of granite before its 

 protrusion by the term "une bouillie aqueuse," a granitic broth. 



These theoretical opinions of M. Scheerer appear to have received 

 the assent of M. Elie de Beaumont and other French geologists*. 

 * See Bulletin de la Soc. Geol. France, new series, vol. iv. p. 1312. 



