420 REACTION OF THE INTERIOR OF THE EARTH 



of activity, and under different local circumstances, 

 give out (for example, at Hecla) 0'81 to 0-83 of nitrogen, 

 and in the lava-streams of that mountain 0-78, with only 

 traces (O'Ol to 0'02) of carbonic acid gas ; other fumaroles 

 in Iceland, as near Krisuvik, give 0-86 to 0-87 of car- 

 bonic acid, with scarcely so much as 0*01 of nitrogen. ( 576 ) 

 In the same manner the important investigations into 

 the emanations of gas in Southern Italy and in Sicily, by 

 Charles St. Claire Deville and Bornemann, show great 

 amount of nitrogen (0'98) in the exhalations from a 

 cleft deep within the crater of Vulcano, but they also 

 show sulphuric acid vapours with a mixture of 74*7 

 parts of nitrogen and 18*5 oxygen; not differing much, 

 therefore, from the constitution of atmospheric air. 

 The gas which rises in the fountain of Acqua Santa ( 577 ) 

 near Catania is on the other hand pure nitrogen, as was 

 at the time of my American journey the gas of the 

 Volcancitos de Turbaco. ( 578 ) 



Are we to suppose that the large quantity of nitrogen 

 which is .diffused by volcanic activity is solely that 

 which is brought to the volcanoes by meteoric water ? 

 or are ther in the interior deeply situated sources of 

 nitrogen ? It is also to be remembered that the air con- 

 tained in rain-water, instead of 0*79, as our common air, 

 has, according to my experiments, only 0-69 of nitrogen. 

 The latter is a source of enhanced fertility by the for- 

 mation of ammonia through the operation of electric 

 explosions, which are of almost daily occurrence within 

 the tropics. ( 579 ) The influence of nitrogen on vegeta- 

 tion is similar to that of the substratum of atmospheric 

 carbonic acid. 



Boussingault, in his analysis of gases from volcanoes 



