244 Dr. Daubeny on ihe 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 hydrogen,) from 
small cavities, shaped like craters, which are filled with 
“muddy water, mixed with petroleum. When I visited the 
spot the action was rather feeble; but there are times when 
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-Volcano, which has been applied to it, 
I 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- 
phate of magnesia and sulphuretted hydrogen gas. Like the 
Harrowgate waters, they are much used for cutaneous dis- 
orders. Ata higher level we lose the rocks belonging to the 
blue clay formation, and find ourselves upon a white sac- 
charoid limestone, of a compact nature, containing kidney- 
shaped masses of flint, like those seen in the chalk-strata, 
which continues to the summit of the mountain. ‘The age of 
this limestone I must leave for other travellers to ascertain ; 
for though I should he disposed, from its general characters, 
to refer it to the same formation as that of Monte Giuliano, 
near Trepani, yet the presence in it of nummulites would lead 
one to suspect a more recent origin. 
Tallude to it however, in this place, only on account of the 
vapour which is continually issuing from the clefis of the 
mountain at its summit, as an evidence, in common with the 
hot sulphur-baths at its foot, of the chemical action going on 
at present among the constituents of the blue clay-formation. 
‘The discovery of this vapour, or rather perhaps its applica- 
tion to medicinal purposes, is attributed to Dedalus, who is 
said to have hollowed out the cavern in which patients are 
exposed to the hot exhalations. At present, the name of 
Deedalus is superseded by that of Saint Calogero, to whom a 
chapel is dedicated close to the spot from whence the vapour 
issues, 
The most southern point at which J recognised the blue 
clay was in the neighbourhood of Terranuova, where it gives 
place toa shelly limestone, alternating with a calcareous 
