essel below; the first
portions being rejected, the remainder was of a beautiful citron yellow
when cold, and entirely pure.

Unlike the refined saltpetre, the purified sulphur had to be pulverized
and bolted like flour before being used. The former was done by two iron
wheels of twelve inches face and five feet diameter, weighing six
hundred pounds each, revolving on a bed circle of iron like the
incorporating rollers; the later was accomplished by bolters, but when
these were worn out and could not be replaced, for want of the silk
cloth, which was not to be found in the South, necessity compelled me to
devise a different, and as it proved, a superior method.

The pulverized sulphur was placed in barrels or cylinders, with hollow
axles, which were made to revolve slowly by machinery; there were ledges
on the interior which caused the sulphur to be lifted and poured over as
the cylinders revolved; a light current of air was blown through each,
entering the hollow axle at one end, and passing out through the axle at
the other end, which led into an adjoining room; there the impalpable
sulphur dust was deposited, much finer than by the usual bolting
process.

Adjoining this Refinery was the department in which charcoal was made
and pulverized. Charcoal for gunpowder has to be made of a porous
fine-grained wood, having very little ashes when burned; willow is
generally preferred, and was used at first in the Powder Works, but the
exigencies of the war taking away those who would ordinarily have
supplied it, rendered it impracticable to procure a sufficient quantity.
Recourse was had to the cotton wood, which was abundant; on trial its
charcoal was found fully equal to that of the willow for the purpose,
and was, thereafter always used.

Charcoal for gunpowder must be made by what is termed the distilling
process; that is, the wood must be heated in iron retorts to the proper
degree, to have it of the best quality and free from sand or grit. For
this purpose cast iron cylinders, or retorts, six feet long and four
feet in diameter were used, placed over furnaces, each having one end
solid and the other with a movable cover; into these were run the slip
cylinders, which contained the kiln dried cotton wood, split up into
sticks about one and a half inches in diameter, and entirely filling it.

The slip cylinders were charged with the wood in an outside apartment,
their covers put on, then readily moved by cranes to the