68 Dr Daubeuy 07i Thermal Springs, 



various gaseous matters disengaged, or the saline efflorescences 

 deposited ; whilst the latter affords a rational solution of the ex- 

 plosions which accompany the paroxysms of a volcano, — of the 

 power which sets in motion the masses of ejected matter, but 

 omits to consider most of the remaining phenomena. On the 

 other hand, the chemical theory, which I have adopted in my 

 treatise, professes to embrace not only all that has been observed 

 to occur in a volcano, as well during the periods of its activity 

 as of its partial intermittence, but also those feebler indications 

 of the same cause which are recognised as taking place in ther- 

 mal waters, and the like. 



But the phenomenon of all others most irreconcileable with 

 the mechanical hypothesis, is that evolution of azotic gas which 

 is so constantly present in warm springs, an effect, which can 

 in no degree be explained by any such cause as the access of 

 water to an incandescent substance, and still less referred to the 

 expression of a portion of any melted matter which the interior 

 of the globe may contain. To suppose it to arise from a dis- 

 tillation of organic bodies imbedded in any of the strata that 

 have been affected by the internal heat, seems equally absurd, 

 since in that case it ought to be evolved most abundantly from 

 rocks which are most rich in organic remains, whereas the very 

 reverse of this appears nearer the truth ; the limestones of the 

 Pyrenees, for example, which give out azote so copiously, if not 

 absolutely without traces of animal matter, containing much too 

 small a quantity to afford a regular supply of this gas. 



Neither would the operation of heat upon animal matter dis- 

 engage this element in the state of purity in which it usually 

 appears. 



pear, indeed, to be simple and necessary consequences of the progressive 

 cooling of the earth." And again, in another passage : " The expansive 

 power of the gases, vrhich, it is very probable, are formed during the consoli- 

 dation of the fluid matter, also explains the origin of earthquakes." I quote 

 these two passages as specimens of the loose manner in which this subject is 

 often treated. The phenomena of volcanos, " explained with such singular 

 felicity," appear to me to reduce themselves to a single one, namely, the 

 emission of lava : for though the reviewer states, that gases are probably 

 formed during the consolidation of the fluid matter, he has nowhere told 

 us in ^hat that probability consists, or why a mixture of lime, alumina, iron 

 and silica, in the proportions which pure lava contain, should copiously evolve 

 aeriform fluids, foreign to their nature and constitution. 



