255 



a period of time sufficiently long to enable him to determine with 

 tolerable precision its average amount, and to ascertain whether 

 any great diurnal variations in its quantity can be detected. He 

 also kept during the same period a corresponding register of the 

 conditions of the atmosphere, as to temperature, humidity and 

 pressure, in order to learn whether any connexion could be traced 

 between these conditions and the quantities of gas evolved. The 

 supplies, both of water and of gas, from the Hot Bath and the Cross 

 Bath being insignificant compared with those from the King's Bath, 

 the author confined his inquiries to the last of these, and chiefly to 

 the gas arising from the apertures within its central area, which is 

 about twenty feet in diameter ; the other apertures without this circle 

 from which gas issued being carefully stopped up. The gas was col- 

 lected by a funnel-shaped apparatus, constructed of several sheets of 

 iron riveted together, and the seams rendered airtight by white lead, 

 supported on a frame, with contrivances for raising and lowering it as 

 occasion might require. The observations were made during periods 

 of from five to fifteen minutes, and continued daily from the 1 7th of Sep- 

 tember to the 1 8th of October inclusive. The average quantity of gas 

 evolved per minute, as deduced from the mean of all the observations, 

 is 267 cubic inches, giving a total daily volume of 223 cubic feet. 



The author, by referring to the accounts on record of other thermal 

 waters, concludes that the evolution of gas is a phenomenon as in- 

 timately connected with the constitution of these waters, as the pre- 

 sence of a definite quantity of certain saline ingredients, or the pos- 

 session of a particular temperature ; both of which probably continue 

 unaltered for periods of indefinite duration, compared with the records 

 of any human history. He considers this phenomenon to be expli- 

 cable, by supposing that a large volume of these gases is pent up in 

 some cavern of rock, at a great depth below the surface of the earth, 

 which, at some former period, had been heated by volcanic action, 

 and which, by the gradual cooling and consequent contraction of its 

 external portions, exerts a continued pressure on the gaseous contents 

 of its cavity, and determines the uniform flow of a stream of gas 

 through crevices towards the surface. 



It appears from the observations of the author that the quantities 

 of gas disengaged, in a given time, from the King's Bath are some- 

 what variable ; for the differences between the results obtained on 

 successive days are too considerable to be ascribed either to errors 

 of manipulation or to variations in the amount of gas escaping by 

 other avenues. These fluctuations in quantity cannot be traced to 

 have any connexion with those of the atmospheric pressure. Varia- 

 tions likewise were observed in the proportional quantities of carbonic 

 acid contained in the gas evolved at different times, which latter vari- 

 ations the author thinks may perhaps be dependent on the former. 



The author remarks, in conclusion, that the immensity of the volume 

 of nitrogen gas which is disengaged from these thermal springs, and 

 the entire absence of carburetted, sulphuretted and phosphuretted 

 hydrogen, seems to afford additional presumption against the truth 

 of the opinion that the nitrogen gas which escapes from volcanoes 



