7^ SIXTH REPORT — 1836. 



refers it to the atmospheric air present in them, the oxygen of 

 which is absorbed by the sulphur found along with it. 



The theory of Berzelius may perhaps suit those cases, in which 

 the quantity disengaged is small, but can scarcely be extended 

 to others, in which it is more considerable. 



No amount of organic matter, that can be supposed to exist 

 in the thermal water, could produce a constant supplj-- of nitrogen, 

 continuing for hundreds and probably thousands of years, equal 

 on an average to 222 cubic feet in the 24 hours, as at the hot 

 spring of Bath. 



It would also have seemed needless to remark, had not the 

 circumstance been overlooked by some who have commented 

 upon this phsenomenon, that the decomposition of organic mat- 

 ter would generate other gases never met with amongst thermal 

 springs, especially carburetted hydrogen, which is actually found 

 to accompany nitrogen in cases where the latter proceeds from 

 organic matter, as was determined, with respect to the gas that 

 renders buoyant the floating island of Derwentwater, by Dr. Dal- 

 ton. 



The explanation of Anglada seems to me only faulty in not 

 being sufficiently general. 



Sulphur no doubt is one of the principles by which the oxygen 

 is abstracted, but it does not seem probable that it should be the 

 only ot)e ; and the case of Bath alone serves to show, that it is 

 sometimes absent altogether from waters, where the evolution 

 of nitrogen is most abundant. 



In short, the only direct inference, that seems deducible from 

 the fact of the copious evolution of nitrogen from thermal 

 waters is, that certain processes, occasioning the abstraction of 

 oxygen from common air, are going on in the interior of the 

 earth. 



This inference remains the same, whether we suppose the 

 nitrogen emitted, to consist merely of that carried down by 

 the atmospheric waters, by which the thermal spring is main- 

 tained, or to be the residue of the atmospheric air, that had 

 found its way into cavities, where these processes are taking 

 place. 



Both explanations may occasionally be true ; but whichever 

 one we choose to adopt, the ultimate fact is still as before, 

 namely, that a quantity of air, which, if derived from the atmo- 

 sphere, contained originally ^th of its volume of oxygen, and if 

 from atmospheric water, vvould contain nearlydouble that amount, 

 returns to the surface, often with scarcely j^o*^' ^^^ ^^ most 

 with not more than xo^'^' '^^ ^^is latter ingredient. 



That atmospheric air does find its way into the interior of the 



