n
that neither Professor Guiscardi nor I, nor indeed any other chemists to
whom I submitted specimens for examination, could detect any. What I can
affirm with certainty is, that these limpid crystals of a yellow colour
were almost always attached to an amorphous substance, soluble in water,
composed of various chlorides, in which iron was often detected.

From these remarks, it is evident that in the tranquil lavas the
sublimations appear with a certain order of succession, and in the
violent lavas, and those which flow most copiously, they are more
complicated, and render both chemical analysis and spectroscopic
researches more difficult. Notwithstanding, I observed traces of lithium
and thallium, which I had previously perceived in some sublimations of
1871. I purpose submitting many sublimations which I have collected to
more complete spectroscopic investigation, although I am persuaded that
the discovery of traces of certain bodies in the sublimations or in the
lavas is a matter of small importance to the science of volcanoes. I
must say, however, that calcium was discovered on this occasion in great
abundance, not only by the spectroscope, but also by chemical analysis.
Sulphate of lime has often been found in larger or smaller proportions,
but this was the first time I had observed chloride of calcium both
close to the craters, and also in the sublimations of the fumaroles upon
the lavas. The white stalactites which I collected beneath the great
mass or bomb above described were almost exclusively composed of
chloride of calcium, and only a few green drops manifested, with the
usual re-agents, the presence of iron.

I did not fail to look often at the spectrum of the flowing lavas
covered with the smoke which issued from them, but I always had a
continuous spectrum. The spectroscope employed was Hoffmann's
construction, with direct vision; but I think it would be better on
other occasions to use a spectroscope combined with a telescope, like
those used by astronomers.

But avoiding minute particulars of these sublimates, let us see what is
the general direction and the order of their appearance. Sublimations
are generally oxides, chlorides and sulphates, sometimes sulphides.
Among the oxides, we must enumerate in the first place "tenorite" and
_feroligiste_ or micaceous peroxide of iron. The first is almost always
found at the commencement of activity in the fumaroles, simultaneously
with the sublimation of ch