256 Dr Daubeny on the Geology of Sicily, 
The sulphate of lime occurs also dispersed in crystals through 
a white clay, and in cavities of the blue clay, accompanied with 
those crystallisations of sulphate of strontian, and of native sul- 
phur, for which Sicily has long been celebrated. 
It would appear that beds of sulphur are found everywhere 
disseminated through the substance of this blue clay formation *, 
for though Sicily has long supplied all Europe with that mine- 
ral, its stores are as yet very far from being exhausted. 
The sulphur occurs either massive or crystallised in octahe- 
drons, but is always of that bright yellow which Brocchi con- 
siders 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 crystallised 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 contained 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 si- 
tuations exposed to the contact of streams of water. The other 
minerals found in this formation are not numerous : iron and 
copper-pyrites are sometimes 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 shew, that a chemical action 
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 on a much 
smaller scale. 
* As for instance, in that of Radebaoy, near Crapina, in Croatia, where the sul- 
phur is met with in balls disseminated through clay, and covered with marl, con- 
taining impressions of fishes, &c., the whole resting on the plastic clay. 
