Page 186 - Dust Explosions in the Process Industries

Case Histories 759

SMALL 9OOM
WITH DOOR
AN0 WINDOWS

Figure 2.1 Reconstruction ofpossible scene of wheat flour explosion in Mr. Giacomelli's bakery on
December 14, 1785, as described by Count Morozzo (1795).

The phzenomenon, however striking at the time it happened, was not entirely new to the baker, who
told me that he had, when he was a boy, witnessed a similar inflammation; it took place in a flour-
warehouse, where they were pouring flour through a long wooden trough, into a bolter, while there
was a light on one side; but, in this case, the inflammation was not followed by an expiosion.
He mentioned to me several other instances, which I thought it my duty to enquiry into; amongst
them, one which had happened to the widow Ricciardi, baker in this city, where (there being, on the
other side of the wall of the flour-warehouse, a lock-smith's forge) the flour was heated to such a degree,
that a boy who went into the warehouse could not remain there, so much were his feet scorched by
the heat; this flour was of a dark brown colour, and whilst the people were examining it, sparks began
to appear, and fire spread itself around, without producing any flame, like a true p);uophorus*.
He also informed me, that an inflammation like that above-mentioned had happened at the house of
a baker in this city, called Joseph Lambert; it was occasioned by shaking some large sacks, which had
been filled with flour, near a lighted lamp, but the flame, though pretty brisk, did cot do any mischief.
According to the foregoing accounts, it appears to me, that it is not difficult to explain the phzenom-
enon in question. The following is the idea I have conceived of it: as the flour fell down, a great quan-
tity of inflammable air, which had been confined in its interstices, was set free; this, rising up, was
inflamed by the contact of the light; and, mixing immediately with a sufficient quantity of atmospheric
air, the explosion took place on that side where there was the least resistance. As to the burning of

* I was very anxious to ascertain by experiments, whether it were possible to bring flour alone into the state
of pyrophorus, but it was in vain; for though I calcined flour with a strong heat, in a small retort, with the
same precautions as used in making other pyrophori, I never could succeed in making it take fire by expo-
sure to the air. By joining alum with it I obtained a true pyrophorus, as Lemery had already done.