Page 185 - Dust Explosions in the Process Industries

158 Dust Explosions in the Process Industries

was a comparatively minor one, but there is still much to learn from Count Morozzo’s
analysis. The considerations related to the low moisture content of the flour due to dry
weather are important and still relevant. The same applies to the primary explosion caus-
ing a secondary explosion by entrainment of dust deposits.
LIV. Account of a violent Explosion which happened in a Flour-Warehouse, at Turin, December the
14th, 1785;to which are added some Observations on spontaneous Inflammations; by Count Morozzo.
From the Memoirs of the Academy of Science of Turin.
The Academy having expressed a desire to have a particular account of the explosion which I men-
tioned to them a few days after it happened, I have made all possible haste to fulfil their desires, by
ascertaining, with the utmost attention, all the circumstances of the fact, so as to be able to relate it
with the greatest exactness.
I shall take the liberty to add to it a short account of several spontaneous inflammations, which
have happened to different substances, and which have been the cause of very great misfortunes.
Although the greater number of these phenomena is already well known to philosophers, I trust the
collecting them together in this place will not be displeasing, as it is impossible to render too well
known facts which so strongly interest the public utility.
On the 14th of December, 1785, about six o’clock in the evening, there took place in the house of
Mr. Giacomelli, baker in this city, an explosion which threw down the windows and window-frames
of his shop, which looked into the street; the noise was as loud as that of a large cracker, and was
heard at a considerable distance. At the moment of the explosion, a very bright flame, which lasted
only a few seconds, was seen in the shop; and it was immediately observed, that the inflammation
proceeded from the flour-warehouse, which was situated over the back shop, and where a boy was
employed in stirring some flour by the light of a lamp. The boy had his face and arms scorched by
the explosion; his hair was burnt, and it was more than a fortnight before his burns were healed. He
was not the only victim of this event; another boy, who happened to be upon a scaffold, in a little
room on the other side of the warehouse, seeing the flame, which had made its passage that way, and
thinking the house was on fire, jumped down from the scaffold, and broke his leg.
In order to ascertain in what manner this event took place, I examined, very narrowly, the ware-
house and its appendages; and, from that examination, and from the accounts of the witnesses, I have
endeavoured to collect all the circumstances of the event, which I shall now describe.
The flour-warehouse, which is situated above the back shop, is six feet high, six feet wide, and
about eight feet long. It is divided into two parts, by a wall; an arched ceiling extends over both, but
the pavement of one part is raised about two feet higher than that of the other. In the middle of the
wall is an opening of communication, two feet and a half wide, and three feet high; through it the
flour is conveyed from the upper chamber into the lower one.
The boy, who was employed, in the lower chamber, in collecting flour to supply the bolter below,
dug about the sides of the opening, in order to make the flour fall from the upper chamber into that
in which he was; and, as he was digging, rather deeply, a sudden fall of a great quantity took place,
followed by a thick cloud, which immediately caught fire, from the lamp hanging to the wall, and
caused the violent explosion here treated of.
The flame shewed itself in two directions; it penetrated, by a little opening, from the upper cham-
ber of the warehouse, into a very small room above it, where, the door and windowframes being well
closed and very strong, it produced no explosion; here the poor boy, already mentioned, broke his
leg. The greatest inflammation, on the contrary, took place in the smaller chamber, and, taking the
direction of a small staircase, which leads into the back shop, caused a violent explosion, which threw
down the frames of the windows which looked into the street. The baker himself, who happened then
to be in his shop, saw the room all on fire some moments before he felt the shock of the explosion.
The warehouse, at the time of the accident, contained about three hundred sacks of flour. Suspecting
that this flour might have been laid up in the warehouse in a damp state, I thought it right to enquire
into that circumstance. I found, upon examination, that it was perfectly dry; there was no appearance
of fermentation in it, nor was there any sensible heat.
The baker told me that he had never had flour so dry as in that year [1785], during which the weather
had been remarkably dry, there having been no rain in Piedmont for the space of five or six months:
indeed, he attributed the accident which had happened in his warehouse to the extraordinary dryness
of the corn.