Outlines of Geology. 259 



Pallas ascribes them to the effect of earthquakes and volca- 

 noes ; some have insisted upon the agency and interference of 

 a comet) and others have attempted to accommodate their specu- 

 lations to the Mosaic history of the creation, and of the deluge, 

 without having broached any particular opinion relative to the 

 cause of the latter phenomenon ; others again have dared to bring 

 the credibility of scripture into the field of their discussions, and 

 have elicited nothing but the contempt and disgust of the wise 

 and virtuous part of mankind. Surely for all these purposes, the 

 deluge is an efficient cause ; and from the evidence already ad- 

 duced, as well as from that which remains to be brought forward, 

 it will be evident that to that source we must ascribe the princi- 

 pal inequalities and irregularities of our present surface. 



We have now reviewed in succession the various strata which 

 incrust the nucleus of our globe, commencing with the most su- 

 perficial, and terminating with those which seem to constitute 

 their foundation, and perhaps even the bulk of our planet. They 

 present us with a series of records singularly interesting and 

 eventful, and will already have appeared "as a book wherein men 

 may read strange matters :" but their history is still imperfect, 

 and I shall endeavour to complete the outline which I have 

 sketched, by examining the contents of mineral dikes and metallic 

 veins, by inquiring into the causes which tend to the disinte- 

 gration and decay of rocks, and by stating the general effects of 

 certain local agents, such as earthquakes and volcanoes. 



Art. IV. — Experiments on the Action of Water upon Glass, 

 with some Observations on its slow Decomposition. By 

 Mr. T. Griffiths. 



[Communicated by the Author.] 



It is a commonly received notion that glass is capable of resisting, 

 to a very great extent, the attacks of active chemical solvents, and 

 that its alkali can neither be readily separated nor exhibited in an 

 insulated form without regularly submitting it to powerful decom- 



