THEORIES OF VOLCANIC ACTION 



IN an address recently before the Swiss 

 Society of Natural Sciences, M. A. 

 Rossel presented certain considerations 

 regarding volcanic action based on ex- 

 periments with the electric furnace. 

 The Literary Digest gives the following 

 summary of the address : 



"A quartz crystal heated in the elec- 

 tric furnace at the relatively low tem- 

 perature produced by 70 volts and 400 

 to 500 amperes is completely volatil- 

 ized ; it is even easy to vaporize lime, 

 magnesia, and in general all compounds 

 containing oxygen, such as silicates, 

 carbonates, etc. 



" Nevertheless, these may undergo a 

 process of reduction ; when we heat in 

 the electric furnace silica with alumina, 

 carbon, iron, etc., new refractory sub- 

 stances are formed, which remain in the 

 furnace while the oxygen is disengaged 

 in the gaseous state. These stable com- 

 pounds are carbids, silicids, phosphids, 

 etc., which resist high temperature, 

 but are all decomposable by water. 



"If we apply this reaction to the 

 formation of the earth by cooling, we 

 must admit that the first minerals pro- 

 duced were compounds of elements . . . 

 free from oxygen. These minerals re- 

 mained in this condition, forming the 

 first terrestrial stratum, until circum- 

 stances permitted the formation of water 

 or water vapor ; as soon as they came 

 in contact with this, a very active re- 

 action must have taken place, whose 

 result was the formation of oxids — 

 lime, alumina, magnesia, etc., together 

 with inflammable gases, whose com- 

 bustion then gave rise to other re- 

 actions. . . . 



' ' There were thus formed, on the one 

 hand, earthy metallic oxids, and, on 

 the other, the oxids that form the acids 

 of the important earths — silicic and 

 carbonic acids. The explanation of the 

 formation of the silicates and carbonates 

 is hence not far to seek. 



' ' Now we may apply what precedes 

 to the explanation of certain volcanic 

 phenomena. 



' ' The earth cools progressively. This 

 cooling gives rise to folds in the terres- 

 trial crust, and fissures may result. 

 Through these fissures water is intro- 

 duced and minerals containing water of 

 hydration may penetrate to a great 

 depth. Then very energetic chemical 

 reactions take place, producing gases 

 that will burn in air, and also metallic 

 oxids. These reactions may cause earth- 

 quakes and volcanic eruptions. 



" In any case, M. Rossel regards it 

 as certain that if the earth has reached 

 its present state by progressive cooling, 

 and if the interior of the globe is now 

 at a sufficiently high temperature to 

 volatilize ox}'genated bodies, oxygen 

 should be entirely wanting at these 

 depths. The oxygen will all be found 

 at the surface of the globe, in the at- 

 mosphere and in combination in water 

 and oxygenated minerals, which are all 

 decomposed volcanic ashes. It would 

 then seem inexact to say that the globe 

 is composed of about four-fifths oxygen 

 and one-fifth other elements. Besides, 

 this hypothesis is not in harmony with 

 what is known of the earth's specific 

 gravity. ' ' 



M 



STANISLAS MEUNIER con- 

 • tributes an interesting and sug- 

 gestive paper on the theory of volcanic 

 outbursts to the Revue Scientifique of Au- 

 gust 2, of which this abstract is pub- 

 lished in The Geographical Journal for 

 December, 1902, He assumes that from 

 the surface down to a certain limited 

 depth, determined by the temperature, 

 all rocks are saturated with water, while 

 beyond that depth the heat is too great 

 for water to penetrate. A fracture of 

 the nature of a reversed fault, caused 

 by thrusting, would place a hot, dry 

 layer below the critical level in contact 



