524 
I'HE 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 plea'iant 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 opening 
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. 
MM. 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 makiug a 
delightful stay in that country about this time last year, the authors 
■wrote to M. Elie de Eeaumont from Pomarana, a letter dated Nov. 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 Nov. 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 diff'erent 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 therapiditj 
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 gazeuscs qui accompaynent I'acide borique dans les Lagoni 
de la Totcane, par MAJ. Ch. Ste. Claire Deville et Leblanc. 
