IN THE MEDITERRANEAN. 
247 
corked, and had not been preserved with any of the precautions requisite to 
have prevented the escape of some of their gaseous contents and the admission 
of atmospheric air. As soon as I received them (it was at night), they were 
inverted in water, and the following morning they were examined. In the 
first-mentioned bottle, which had been full of air, a little water had entered so 
as to fill about half its neck. On withdrawing the cork under water, water 
rushed in equal to about one quarter of the capacity of the bottle. The air 
remaining had a slight smell of sulphuretted hydrogen ; it extinguished a taper 
plunged into it, and was not itself inflammable; 50 measures of it by lime- 
water were reduced to 16; and these by phosphorus were reduced to 13 
sulphur sublimed in this residue occasioned no alteration of volume. 
The air in the other bottle containing some water had no smell of sulphu¬ 
retted hydrogen ; 48 measures of it by lime-water were reduced to 33, and 
these by phosphorus to 31; and this residue was not inflammable, anti extin¬ 
guished flame. 
From these results it may be inferred that the gas in the first-mentioned 
bottle consisted chiefly of carbonic acid and azote and a little oxygen with a 
trace of sulphuretted hydrogen ; and that the gas in the second bottle was 
principally azote with a little oxygen and carbonic acid. Considering the 
manner in which the bottles had been kept, it is highly probable that the azote 
and oxygen were derived from atmospheric air, unconnected with the volcano, 
and that the carbonic acid and trace of sulphuretted hydrogen alone were of 
volcanic origin. The presence of the acid gas is easily accounted for, supposing 
it to be derived by the action of heat from rocks containing carbonate of lime 
and magnesia, earths which we have seen are contained in the cinders and 
ashes ejected. In one place outside of the volcano, in the sea, Captain Wode- 
house observed a great bubbling of air, as if the water was boiling ; he ap¬ 
proached it and even went over it in a boat, and found its temperature not 
above that of the adjoining surface, and there was no peculiar odour percep¬ 
tible. It is to be regretted that none of this gas was collected; but, probably, 
it also was carbonic acid gas, and arising from the calcining effect of heat on 
the subjacent rocks forming the bed of the sea. Shortly after, it is said, the 
bubbling continuing, the water became very hot, which is confirmatory of the 
above conjecture. 
2 k 2 
