/ 
Dr. Daubeny on the Geology of Sicily. 243 
‘The sulphur occurs either massive or crystallized in octa- 
hedrons, but is always of that bright yellow which Brocchi 
considers as proof that the mineral has been sublimed, and 
never of the liver-hue, which belongs to it in some districts. 
The blue clay likewise contains beds of rock salt, of which 
the most considerable are at Alimina, NE. of Castrogiovanni, 
where this substance is found both massive and crystallized 
in cubes. The springs that issue from this formation have 
always more or less of a brackish taste ; and I found, on the 
application of proper tests, that they contain much muriate 
of soda, some sulphate of magnesia, and sulphate of soda. 
These latter salts were found also incrusting the sides of 
ravines, and in other situations exposed to the contact of 
streams of water. The other minerais found in this forma- 
tlon are not numerous; iron and copper pyrites are some- 
times met with, and, I believe, sulphate of barytes, and alum. 
In a country, in short, so replete with sulphur, all the 
combinations of that mineral, or of the sulphuric acid with 
the different bases, are to be looked for; and most of them 
accordingly are found. 
It is, indeed, probable, that the formation of these sulphuric 
salts, and the sublimation of the sulphur, are taking place in 
many parts of this formation, even at the present moment, for 
there are abundance of facts which show that a chemical ac- 
tion is going on among the inflammable materials which it 
contains, giving rise to the production of heat, and to the 
disengagement of elastic vapours; to phenomena, in short, 
which present some analogy to those of volcanoes, although 
exhibited ona much smaller scale. 
It is not long since the proprietor of some land in the in- 
terior congratulated himself on his good fortune, in being able 
to collect a large supply of sulphur -tready purified, by 
merely placing vessels to receive a strel > of that substance, 
which was constantly issuing from ther de of 2 hill. This 
was occasioned by a bed of sulphur in the interior of the 
mountain having caught fire, and the heat generated by the 
combustion of one portion serving to melt the remainder; 
Nature having, in this instance, adopted the wasteful process 
employed from time immemorial by the Sicilians, for getting 
rid of the intermixed clay, which consists simply in collecting 
the materials in large heaps, and setting fire to them on the 
surface, thus causing the liquefaction of one, portion by the 
combustion of another. 
