quite the same
as the ashes.

But at the beginning of the eruption of the 26th April, a white sand
fell in the Atria del Cavallo, close to the Crocella[5], which on the
dark scoriae of 1871 looked like snow. Its fall had a limit so well
defined that one passed without any gradation from white to black.
Having collected some of this sand that very morning, I put it up in
white paper, for at that moment it was impossible for me to examine it.
Taking it out some days after, I found it had become reddish, and having
put it under the microscope, I observed that it was exclusively formed
of little pebbles more or less round, of a transparent vitreous matter,
partly covered with a red substance. Fragments of green crystals
occurred in this sand, upon which no red was perceptible. I consulted
our eminent crystallographer, Arcangelo Scacchi, whether these little
pebbles were leucite, as I suspected, and whether the green particles
were pyroxene: he confirmed my suspicion, and remarked that the red
colour was superficial only. We then washed a little of the sand in hot
water, and saw the pebbles become whitish; but having heated some on
platinum, we observed that they first turned black and then became
perfectly white, proving that the red was a deposit of organic matter.
To see these leucites, rounded like small pebbles transported by a
torrent, deprived of the soluble chlorides which generally accompany
Vesuvian ashes, is a matter worthy of attention. Whilst heating this
sand upon platinum, decrepitation was audible, which indicated the
cracking of some of the little pebbles. It is evident, therefore, that
crystals of leucite raised to a certain temperature may break, and thus
we can understand how almost all Vesuvian ashes contain fragments of
the said crystals enveloped in the paste of the lava. It is evident that
the soluble part of the ashes is obtained from the smoke through which
it passes. On this occasion the smoke from the craters did not
apparently contain much acids, for no bad smell was perceptible, and the
water in which I washed the ashes scarcely reddened litmus paper. Even
chloride of iron, which was so abundant in the lavas, was scarcely
perceptible in the smoke, which almost exclusively deposited sea-salt on
the surrounding rocks; I say sea-salt advisedly, and not chloride of
sodium, to show that I include all that sea-salt contains. The slight
disturbance it manifested with chloride of barium, and the small