Intelligence and Miscellaneous Articles. 239 



the earth's crust has evidently the greatest thickness and reposes 

 on the deepest internal prominences ; and to the occasional slides 

 and ascending movements of matter from these parts of the subter- 

 ranean regions, we may ascribe the prevalence of vulcanicity on so 

 many continental coasts. 



If only one per cent, of terrestrial matter passed into a solid form 

 in the course of ten millions of years, there would be still sufficient 

 grounds for assigning to rock-slides a mass so great that the me- 

 chanical effects of their collisions against the thinner parts of the 

 crust may produce the most violent earthquake shocks. But the most 

 obvious effects must be ascribed to the sudden elevation of tempera- 

 ture which the thin spots of the earth's crust should experience, 

 and which may be reasonably estimated at many thousand degrees. 

 Exposed to such a fierce heat, the solid structure would be rent by 

 the unequal expansion of its parts, or by the elasticity of its volatile 

 constituents. Steam would manifest an irresistible power when 

 rock containing moisture tumbled into the molten liquid or encoun- 

 tered it when penetrating through fissures. But a motive power 

 of long continuance would arise from the property which silica has 

 of expelling other acids from bases at high temperature. As the si- 

 liceous rocks come into collision with the strata containing limestone 

 or any other carbonates, the resulting mass should swell with the 

 evolution of carbonic acid, and boil over a volcanic crater or even 

 open a new one. In consequence of the pressure, this expulsion of 

 carbonic acid will require a higher temperature ; and the cooling, 

 chiefly through the agency of water, would soon occasion a state of 

 repose until there occurred a new influx of heated matter from 

 deep regions. An estimate of the rate of cooling, as involved in 

 the mere production of steam alone, would show that, during their 

 numerous eruptions, Etna and Vesuvius must have lost a quantity 

 of heat too great to be supplied by any conceivable chemical or 

 mechanical action in their immediate vicinity ; and evidence may be 

 thus obtained of the necessity of the convection of caloric, and of 

 the introduction of incandescent matter from distant localities to 

 the theatre of volcanic activity. 



Cincinnati, O., July 15, 1874. 



ON THE CONVERSION OF ORDINARY INTO AMORPHOUS PHOS- 

 PHORUS BY THE ACTION OF ELECTRICITY. 



In the Anzeiger of the Imperial Academy at Vienna, Professor 

 v. Schrotter gives the following notice of this transformation, dis- 

 covered by Dr. Geissler : — 



Already in 1860 Dr. Greissler endeavoured to show that electri- 

 city by itself effects this change ; and he had the goodness, on the 

 occasion of his visit to Vienna at the time of the Universal Expo- 

 sition, to give up to me some of the glass apparatus. 



The simplest of these is an exhausted glass tube of about 35 cen- 



