The upper or feed valve opens upward and has a downward projecting lip
that shuts into a recess in its seat which insures security against
leakage from the hopper to the hulling cylinder during the intervals of
its being raised; a great advantage in hominy making, as no grain ought
to get into the batch until that in the cylinder is done.
Patented Oct. 15, 1867, by John Donaldson, who may be addressed for
further information at Rockford, Ill.
* * * * *
Nitro-Glycerin.
Professor Doremus of this city was called as a witness at the inquest
upon the bodies of the unfortunate persons killed by the recent
explosion at Bergen, N.J. The Professor having previously analyzed some
of the explosive mixture, testified as follows:--"I have subjected it
to chemical analysis, and find it to correspond to the formula C_{6},
H_{3}, O_{3}, and NO_{5}; it is well made nitro-glycerin; the substance
freezes at about 46; it is made to decompose in a very peculiar way; on
moistening paper with it it burns with rapidity; it does not explode
when red-hot copper is placed in it; we tried it with the most intense
heat--we can produce with a galvanic battery with two hundred cells
holding a gallon and a half each; some nitro-glycerin was placed in a
cup and connected with one of the poles of the battery; through a pencil
of gas carbon the other poles of the battery were connected with the
glycerin, no explosion ensued; but when the point touched the britannia
vessel the nitro-glycerin took fire, a portion burning and the rest
scattering about; this is as severe a test as we can submit it to in the
way of heat under the pressure of the air; we therefore would conclude
that nitro-glycerin carried about exposed cannot explode, even if you
drop a coal of fire into it; if the liquid is confined, or is under
pressure, then an explosion will ensue; if paper be moistened with
it and put on an anvil and a smart blow given with a hammer, a sharp
detonation ensues; if gunpowder or the fulminates of mercury, silver or
gun-cotton be ignited in a vacuum by a galvanic battery, none of them
will explode; if any gas be introduced so as to produce a gentle
pressure during the decomposition, then a rapid evolution of gases will
result; the results of decomposition in a vacuum differ from those under
atmospheric pressure or when they are burnt in a pistol, musket,
a cannon, or in a mine; where we have little or no pressure it is
difficult to get these substances to burn rapidly; nitro-glycerin is
more difficult to explode than powder; in many respects it resembles
gun-cotton which is made in a similar way; if gun-cotton be immersed
in the proto-chloride of iron it turns into common cotton; the
same experiment was tried with nitro-glycerin by mixing it with
proto-chloride of iron, and it reverted into common glycerin; there
are four well known varieties of gun-cotton made by employing acids of
different strengths; they differ in chemical composition and properties,
as well as in their explosive qualities; the late Minister of War in
Austria in 1862 stated to me that he had ordered four hundred cannon for
gun-cotton, and six months after he stated that he had ordered all
the cannon to be changed and adapted to powder, in consequence of
spontaneous combustions; much less is known of nitro-glycerin than of
gun-cotton, and probably several varieties of this article may be formed
as of gun cotton; this would explain cases of spontaneous explosion; if
the nitro-glycerin is not carefully washed to get rid of the acid, a
gradual decomposition will ensue, producing gases, which, if the vessel
be closed, will explode; my opinion is that nitro-glycerin should be
used in the most careful hands; do not think I would put it in the hands
of a common laborer for blasting purposes; it is less dangerous in a
frozen than a liquid state; I think concussion would explode frozen
nitro-glycerin.
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