524 



THE GEOLOGIST. 



Christian church in the later Byzantine style. , .... In a forecourt 

 situated to the east, the flame breaks out of a fireplace-like opening, 

 about two feet broad and one foot deep, in the serpentine rock. It rises 

 to a height of three or four feet, and diffuses a pleasant odour, which is 



perceptible to a distance of forty paces At a distance of three 



paces from the flame of the Chimoera the heat it gives out is scarcely 

 endurable. A piece or dry wood ignites when it is held in the openiug 

 and brought near the flame without touching it." And this magnifi- 

 cent phenomenon has been going on for several thousand years I 



This bring us naturally to the subject of gaseous emanations, and we 

 have at this moment before us a paper quite fresh upon the subject. 



M!M. Ch. Deville and Leblanc have been studying for some time 

 past the nature of the gaseous emanations which accompany, as a rule, 

 the deposit of boracic acid in the lagoni of Tuscany. Whilst making a 

 delightful stay in that country about this time last year, the authors 

 wrote to M. Elie de Beaumont from Pomarana, a letter dated l^ov. 2, 

 1857, in which they stated, as the result of their united experiments, 

 that the gases which are evolved with the boracic acid appear to 

 consist, independently of a great quantity of aqueous vapour, of sul- 

 phuretted hydrogen and carbonic acid, which predominate; oxygen 

 gas was only found in very minute quantities, and appeared to be 

 altogether absent when the gases were collected with great care. 

 These facts had, however, already been made known by M. Payen and 

 Professor Schmidt. But MM. Ch. Deville and Leblanc added, in their 

 letter of the 9th jN'ov. 1857, that in all the places they had visited they 

 had found small quantities of carburetted hydrogen gas mixed with 

 nitrogen (besides the gases already named), but which they had not 

 then analysed. 



We have now, since the date given above, some new details on this 

 subject by the same authors. It would be useless here to enter into 

 particulars concerning the manner in which the ditierent gases were 

 collected, measured, and analysed, and the different apparatus employed 

 for this purpose ; it will be sufficient, I think, to state that the aeriform 

 fluids were collected with the greatest possible care, and their analysis 

 conducted in such a manner as to ensure the greatest possible accuracy. 

 An interesting paper presented by the authors to the Academy of Sciences 

 at Paris, on the 23rd of August last, and subsequently published, fur- 

 nishes us with the following facts* : — 



1. The temperature of the gases, whether collected from the soffioni 

 or from certain artesian wells, is, at the surface of the earth, as much 

 as 100^ (centigrade), but never exceeds this point, although therapidit)^ 

 with which the gases are evolved seems, in many cases, to indicate 

 an internal pressure. 



2. All these gaseous emanations, from whatever point they proceed, 

 contain the same gases, and pretty nearly always in the same propor- 

 tions. Carbonic acid predominates in quantity, as M. Payen had pre- 

 viously made known. The quantity of sulphuretted hydrogen is to 



* Sur les emanations gazeuses qui accompaynent I'acide borique dansles Lagoni 

 de la To&cane, par MM. Ch. Ste. Claire Deville et Leblanc. 



