Qh Dr. Daubeny on the Geology of Sicily, 
At Macaluba, a hill near Girgenti, consisting of blue clay, 
there is a continual disengagement of gas, (which I found to 
consist of carbonic acid and carburetted bydrogens) ae 
small cavities, shaped like craters, which are filled w 
muddy water, mixed with petroleum. When 1 visited. t 
spot the action was rather feeble; but there are times w 
the quantity of gas emitted is so great, as to throw up | the 
mud to the height of 200 feet, so as almost to justify the name 
of an Air-Voleano, which has been applied to it, 
shall mention only one other proof of the same fact, 
which is exhibited near the town of Sciacca, the ancient 
baths of Selinus. On the slope of Mount Calogero, the an- 
cient Mons Gronius, at the back of the above town, are baths 
of which the temperature is no less than 120° of Fahrenheit, 
and which, from their sensible qualities, seem to contain sul- 
pate of magnesia and sulphuretted hydrogen gas. Like the 
arrowgate waters, they are much used for cutaneous dis- 
orders. At a higher level we lose the rocks belonging to the 
blue clay formation, and find ourselves upon a white sac- 
charoid limestone, of a compact natute, scons na kidney- 
shaped masses of flint, like dhoos seen chalk-strata, 
which continues to the summit of the aia: The age of 
« lenetions I must leave for other travellers to ascertain ; 
yugh I should he disposed, from its general characters 
o refer same formation as that of Monte Giuliano, 
near Trepani, yet the presence in it of nummulites would lead 
one to suspect a more recent 0 rigin 
Tallude to it however, i in this place, only on account of the 
vapour which is ne issuing from the clefts of the 
mountain at. its summit, as an evidence, in common with the 
hot sulphur-baths at pe foot, of the chemical. action going 01 on 
at present among the constituents of the clay-forma 
The discovery of this vapour, or rather nese its = applica 
tion to medicinal purposes, is attributed to Deda 
said to have hollowed out the cavern in which Saene are 
exposed to the hot exhalations. At present, the name of 
Dedalus is superseded by that of Saint Calogero, to whom a: 
chapel is dedicated close to the spot from whence the vapour 
issues. 
The most canoer Epa at which I recognised the blue 
clay was in the of Terranuova, where it gives 
place toa abelty faa alternating with a calcareous 
