Gay Lussac on Volcanoes. 133 



than that of lava, it is by no means probable that it has been 

 volatilized in that state. It has, most likely, been primitively 

 in the state of chloride. If, indeed, we take protochloride of 

 iron which has been fused, expose it to a dull red heat in a glass 

 tube, and then pass over its surface a current of steam, we shall 

 obtain much muriatic acid and hydrogen gases, and there will 

 remain in the tube black deutoxide of iron. The perchloride of 

 iron is very volatile ; and becomes so hot with water, that, on the 

 large scale, the mixture might become incandescent. If chlorides 

 of silieium and aluminum exist in the bowels of the earth, their 

 action with water would be far more energetic. M. Gay Lussac 

 does not believe in the agency of sulphur in volcanoes ; and finds 

 a difficulty in accounting for the presence of sulphurous acid, if it 

 really exist. He shews that basalts, cannot owe their black colour 

 to carbon ; for in that case, by ignition, metallic iron would be 

 formed in them. He thinks that it is sea water which most usually 

 penetrates into the heart of volcanoes . He illustrates the extent of 

 the earthquakes which accompany eruptions, by the vibratory 

 effect produced en a long beam, when one end of it is struck with 

 a pin-head ; and by the shaking of vast edifices, and of even the 

 profound quarries at Paris, by the rattling of carriages on the 

 streets. Why should it be astonishing, therefore, concludes he, 

 that a very strong commotion in the bowels of the earth shall 

 make it tremble throughout a radius of several hundred leagues. — 

 A/i». de Chim. ct de Phys. xxii. 415. 



