ANNIVERSARY ADDRESS OF THE PRESIDENT. CX111 



1. 



Sulphuric Acid 2*6 



Oxygen 18*7 



Nitrogen 78*7 



Vesuvius. 

 2. 3. 



2-4 0-3.... 



Vulcano, 

 Vents with flame. Without flame. 

 1. 2. 

 391 27*5 69 6 



19-7 17-6 , , 

 77-9 82-1.... 



551 58.5 249 



100-0 100-0 100-0 100-0 100-0 



Oxygen in 100" 



c P ombmedox h y! \ '« «« 17 ' 6 9 ' 6 19 ' 4 18 ' 8 



gen & nitrogen _ 



Now, as the normal proportions of oxygen and nitrogen are 20 or 

 21 0_ and 80 or 79 N, it is evident that in few instances were the 

 true proportions of normal air preserved, whilst in several the pro- 

 portion of nitrogen was greatly in excess. The fact, therefore, that 

 nitrogen appears in a portion of the gaseous emanations of volcanos, 

 cannot be doubted; but, as oxygen appears contemporaneously with it, 

 the question still remains to be answered, whether the atmospheric air, 

 of which it appears to have once formed a part, has only been 

 sucked into the mouth of the crater, or whether it has been carried, 

 either in combination with water, or in any other state, deep into the 

 interior of the earth or down to the very focus of volcanic action. It is 

 somewhat remarkable, indeed, that the gases of Vulcano, which are 

 accompanied with vapour, and contain air so poor in oxygen and so. 

 rich in nitrogen, are those which, as stated by Mr. Warington, 

 deposit sulphur, boracic acid, and muriate and hydriodate of am- 

 monia, exhibiting therefore so great an excess of nitrogen as almost 

 to demonstrate that the reactions which gave rise to the production 

 of ammonia and the collection of an excess of nitrogen must have 

 been internal. The gas proceeding from the spring of Santa Yene- 

 rina on the flank of Etna yields nitrogen entirely free from oxygen ; 

 and M. Deville states that he looks upon volcanos as vast chimneys 

 into which, by means of the lateral fissures connected with them, the 

 atmosphere is sucked in, and there freed by combustion of all or 

 part of its oxygen, and that the emanations from vents in a plane of 

 eruption exhibit a combustion less and less energetic as it recedes 

 from the centre of activity, which corresponds with the view already 

 enunciated, — namely, that in any one vent the intensity of action will 

 diminish in proportion to the time elapsed since the commencement 

 of the eruption, but in many contemporaneous vents the intensity 

 will be in proportion to their distance fiom the focus of eruption or 

 main crater. This notice of the labours of M. Deville will, it is 

 trusted, convey an adequate idea of their importance, either as bear- 

 ing upon the subject brought under our notice by Dr. Daubeny, or 

 upon the still higher generalizations of physical geology. The ope- 

 rations of the volcanic laboratory may be investigated in the labo- 

 ratory of the chemist, and, when once satisfactorily explained, afford 

 a clue to the investigation of phaenomena, of which the mode of 

 production has long since been veiled from direct observation. 



M. J. Durocher has directed his attention to another form of this 

 interesting inquiry, and has studied with much attention the chemical 



