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The muriatic acid of the sea-water also meeting with sulphur * is converted 
into the sulphuric acid, which in a diluted state, acts upon iron, and thus 
Yulcano. Here it may be said to be about a hundred times louder. Under this bottom we seem to 
hear a river running, or rather a conflict of agitated waves which meet, and impetuously clash toge¬ 
ther. The ground, likewise, in some places, cleaves in cracks, fissures and apertures, from which 
hissing sounds issue resembling those produced by the bellows of a furnace. I therefore thought there 
was every reason to conclude, that these sounds are occasioned by an elastic gas which issues through 
those fissures; and was afterwards perfectly convinced of the truth of this supposition by the following 
facts. If the hand be approached to any of these apertures, a strong impression is felt of an extremely 
subtle invisible fluid; and, if a lighted candle be applied to them, it will, it is true, be frequently 
extinguished by the impetus of the fluid, but sometimes it will set fire to the fluid itself, producing a 
flame of a bluish red colour which lasts for several minutes. The fetid odour which is then perceived 
convinced me that it is a sulphurated hydrogenous gas.” Vide Travels in the Two Sicilies, &c. 
* Sulphur is extracted from pyrites, an ore common to many parts of the world, and it is also 
found mixed with different earths, but is only met with in its pure state in the neighbourhood of vol¬ 
canos, or as deposited by springs strongly impregnated with sulphur. All France, and great part of 
Europe, is furnished with sulphur from the mines of Solfatara in Italy> where the earth is found most 
to abound with this mineral. 
The valley of Salfatara, near Naples, seems to exhibit, in a minute degree, whatever is seen of 
this horrible kind on the great theatre of nature. This plain, which is about twelve hundred feet long, 
and a thousand broad, is embosomed in mountains, and has in the middle of it a lake of noisome 
blackish water, covered with a bitumen, that floats upon its surface. In every part of this plain 
caverns appear smoking with sulphur, and often emitting flames. 
This famous mine is an oval plain, the greatest diameter of which is about four hundred yards, 
raised about three hundred yards above the level. Almost all the surface is bare and white, like marie; 
and is every where sensibly warmer than the atmosphere in the greatest heat of summer; so that the 
feet of persons walking there are burnt through their shoes. It is impossible not to observe the sulphur 
there; for every where may be perceived by the smell a sulphureous vapour, which rises to a consider¬ 
able height, and gives reason to believe that there is a subterraneous fire below, from which that vapour 
proceeds. Near the middle of this field there is a kind of bason three or four feet lower than the rest 
of the plain, in which a sound may be perceived when a person walks on it, as if there were under his 
feet some great cavity, the roof of which was very thin. After that, the lake Agnano is perceived, 
whose waters seem to boil. These waters are indeed hot, but not so hot as boiling water. This kind 
of ebullition proceeds from vapours which rise from the bottom of the lake, which being set in motion 
by the action of subterranean fires, have force enough to raise all that mass of water. Near this lake 
there are pits, not very deep, from which sulphureous vapours are exhaled. Finally, there are some 
deeper excavations, whence a soft stone is procured which yields sulphur. From these cavities vapours 
exhale, and issue out with noise, and which are nothing else than sulphur subliming through the cre¬ 
vices. This sulphur adheres to the sides of the rocks, where it forms enormous masses: in calm 
weather the vapours may be evidently seen to rise twenty-five or thirty feet from the surface of the 
earth. These vapours, attaching themselves to the sides of rocks, form enormous groups of sulphur, 
which sometimes fall down by their own weight, and render these places of dangerous access. In 
entering the Solfatara, there are warehouses and buildings for the refining of sulphur. Under a great 
shed, or hangar, supported by a wall behind, open on the other three sides, the sulphur is procured 
by distillation from the soft stones we mentioned above. These stones are dug from under ground; 
and those which lie on the surface of the earth are neglected. These last are, however, covered with 
a sulphur ready formed, and of a yellow colour; but the workmen say they have lost their strength, 
and that the sulphur obtained from them is not of so good a quality as the sulphur obtained from the 
stones which are dug out of the ground. These last-mentioned stones are brokerHn dumps, and put 
into pots of earthen-ware, containing each about twenty pints, Paris measure. Yide Macquer’s 
Chemical Dictionary. 
