38 SIXTH HKrORT — 1836. 



springs of tliat u;iteriug-pl;icc arise, but is observed for some 

 distance round, wherever fissures, natural or artificial, exist. 



Thus, a cavity having been made by some workmen for quarry- 

 ing stone, it was found, that the air witliin became charged with 

 from 36 to 48 per cent, of carbonic acid, which rose in the 

 cavern to different lieights at different times. 

 Its v.iii- These writers report, that in winter the gas never attained so 



atioiis. high a point as at other seasons ; that in the morning, some 

 hours after daybreak, and in the evening, soon after sunset, the 

 mephitic air liad reached its maxiumm, whilst at midday, when 

 the sun shone into the cave, it was very low ; that the evolution 

 of gas was greatest before tlie breaking out of a storm, but dimi- 

 nished after it had begun ; that the variations of barometric 

 pressure seemed to exert no influence upon the phenomenon, 

 except so far as they were connected with the occurrence of a 

 storm ; tliat it was greater during hot weather than cold ; in 

 calm than in windy ; in a moist state of the atmosphere than in 

 a dry one. A similar remark has been made with respect to the 

 disengagement of carbonic acid in Auvergne*, as that recorded 

 as to Pyrmont, the quantity given out being so large during 

 storms, and during the prevalence of a westerly wind, as to 

 render some of the mines unworkable. 



Kastner f also alludes to the variation as to quantity, both in 

 the water and the carbonic acid,observed atKissingen in Bavaria, 

 and attributes it in both cases to a difference in atmospheric 

 pressure, the water being forced out by the gas, and the escape 

 of the latter checked, in proportion to the weight of the atmo- 

 sphere above. 



According to Mayen, the springs of Bochlet have a regular 

 ebb and flow, both as to the amount of water and of gas. The 

 greatest difference in quantitj^ corresponded with the interval 

 between the first and last of the moon's quarters. At Fachin- 

 genj the quantity of gas evolved is said to be greatest just 

 before sunrise, and least about two or three o'clock after mid- 

 day. 

 Its amount. The auiouiit of carbonic acid given off has in a few instances 

 only been determined §. 



Trommsdorft" found the quantity evolved from a fissure at 

 Kaiser Franzeiibad, near Egra, to amount to 5760 Vienna cubic 



* Fournet Aiinules Scientifiqucs de I' Auvergne, vol. ii. p. 241; or Ferussac's 

 Bulletin, for 1829. 



t Archiv, vol. xvi. + Kastner, Archie, vol. i. 



§ See G. BischofF in Edhdturijh New Philosophical Journal, 1833, from 

 PoggcudorflF's Aimalen. 



