202 REACTION OF THE INTERIOR OF THE EARTH 



shown to be the case in the very pure spring which flows 

 from granite rock in the Trincheras de Portocabello, ( 276 ) 

 and Bunsen ( 277 ) in the Cornelius spring at Aix-la-Cha- 

 pelle, and in the Geysirs of Iceland. The organic 

 matter which is held in solution in several springs is also 

 nitrogenous, and even sometimes bituminous. Formerly, 

 before it was known by Gay-Lussac's and my own expe- 

 riments, that rain and snow-water contain (the first 10 

 and the last at least 8 per cent.) more oxygen than the 

 atmosphere, it was thought very surprising that it should 

 be possible to obtain from the springs of Nocera, in the 

 Apennines, mixture of gases in which there was an 

 abundance of oxygen. The analyses of Gay-Lussac, 

 made while we resided near this mountain-spring, 

 showed that it contained no more than the amount of 

 oxygen which it could derive from rain or snow. ( 278 ) If 

 we are disposed to wonder at the silicious deposits which 

 in the Geysirs appear more like building materials, out 

 of which nature has put together forms resembling arti- 

 ficial constructions, we may be reminded that silica is 

 also contained in many cold springs which have in them 

 only a very small portion of carbonic acid. 



Saline springs and exhalations of carbonic-acid gas, 

 which were long ascribed to beds of coal and lignite, 

 appear to be due wholly to processes of deep-seated vol- 

 canic activity; an activity, not manifesting itself solely 

 where volcanic rocks testify the existence of ancient 

 local igneous eruptions, but everywhere diffused. Car- 

 bonic-acid exhalations are, indeed, the phenomena which 

 in extinct volcanoes longest survive plutonic catastrophes : 

 they succeed to the stage of solfatara activity ; but at the 

 same time waters of the most different temperatures 



