IMPROVEMENTS IN EXPLOSIVE COMPOUNDS
Year: 1876

page_text: LETTERS PATENT to Egbert Judson, of the City and County of San Francisco,
State of California, in the United States of America, for the Invention of
"IMPROVEMENTS IN EXPLOSIVE COMPOUNDS."
he 12th January 1877, and dated the 25th November 1876.
COMPLETE SPECIFICATION filed by the said Egbert Judson at the Office of
the Commissioners of Patents on the 25th November 1876.
EGBERT JUDSON, of the City and County of San Francisco, State of California,
in the United States of America. "IMPROVEMENTS IN EXPLOSIVE COMPOUNDS."
In that special class of explosive compounds formed by mixing nitro-glycerine
with various gas producing solid substances it is usual, in order to promote a rapid
decomposition of the entire compound, to reduce the solid substances used to a state
of comminution, and to mix them intimately with each other and with the nitro-
glycerine.
For the purpose of this Specification I term these solid substances the dry
mixture. These dry mixtures as heretofore prepared and used could only be con-
verted into a useful explosive by the addition of a large proportion of nitro-glycerine,
seldom less than fifteen per cent. being found practically effective, while in fact from
thirty to forty per cent. was generally used. The necessity for so large a proportion
of nitro-glycerine arose from the fact that if only a small quantity were used in a
short time after its introduction it was so completely absorbed or taken up by the
dry mixture that the compound became practically inexplosive. Moreover, these
dry mixtures being in general largely composed of some one of the nitrates, are
more or less hygroscopic, and consequently very liable to injury from moisture
absorbed from the atmosphere or otherwise.
The object of my Invention is to convert these absorbent and deliquescent gas
producing substances into comparatively non-absorbent and non-deliquescent
particles before adding the nitro-glycerine, so that the said particles will not only
be measurably prevented from absorbing moisture to the detriment of the compound
but will also be rendered incapable of absorbing to any great extent the nitro-
glycerine which is subsequently added to render the compound explosive. My
explosive compound will then consist of grains or particles of a gas producing
substance sealed or enclosed in a combustible, non-absorbent substance, while the

page_text: non-absorbent exterior or surfaces of each particle will be covered, coated, or sur-
rounded with a thin film of nitro-glycerine.
The very small quantity of nitro-glycerine which is required by this Invention
to render these non-absorbent particles explosive enables me to cheapen the cost
of producing the compound, and also greatly reduces the danger of accidental
explosion.
The mode by which I accomplish this object is to varnish, cement, or coat, as
herein-after described, the grains of nitrate of the dry mixture, and also if necessary
the carbon or any other part that may be porous or absorbent with a varnish or
cement composed of combustible substances that will liquify by heat, or some highly
volatile solvent, which varnish or cement I can make from certain substances that
ordinarily form parts of the dry mixture itself.
If the dry mixture or such part of it as is to receive the varnish or cement be
extremely fine or pulverulent this operation of varnishing or cementing will
granulate it into grains of a suitable size for powder by cementing the finer particles
together, but if it be coarser its grains or particles will simply receive the coating
or varnishing required by my Invention.
After the dry mixture has been treated and prepared according to my Invention
it will be found that its grains thus coated, varnished, cemented, or smeared will
receive and retain the nitro-glycerine upon their surfaces, or mainly upon their
surfaces, with little or no absorption, thus enabling a very small proportion of
nitro-glycerine to maintain its continuity throughout the mass, and thereby render
the whole explosive; and, further, will be measurably protected from dampness.
The dry mixtures of the particular class of explosives in question generally
contain, in addition to a large proportion of some one of the nitrates, carbon and
one or more of the hydrocarbon resinous or bituminous substances, and in addition
sulphur is frequently used.
Of the first three ingredients mentioned there are under each designation respec-
tively a large number of substances that may be substituted one for the other, thus
allowing variations to an almost unlimited extent. In effect however all will
accomplish the same purpose in a varying degree, and all may be used in connection
with my Invention.
Cheapness and efficiency combined will determine which substances shall be
used, and I consequently proceed to illustrate my Invention by stating one of the
many formulas which will produce a superior explosive compound, confining myself
to the cheap and ordinary ingredients of a dry mixture. Take by weight as
follows: Sulphur, 15 parts; resin, 3 parts; asphalt, 2 parts; nitrate of soda, 70
parts; and anthracite coal, 10 parts. Let the sulphur, resin, and asphalt be melted
together, and well stirred. Into this mixture while melted the nitrate of soda and
the coal, both pulverized and thoroughly dried, are to be mixed and well stirred
until thoroughly varnished, cemented, or coated by the melted mixture, care being
used that the degree of heat be not suflicient to create danger of firing the mass.
It is better that both nitrate and coal should be hot when introduced. The entire
mixture should thereafter be gently but constantly stirred until cool, so that the
grains cease to adhere to each other. The dry mixture is then complete, and ready
to receive the nitro-glycerine, which may be added as desired. One, two, or three
per cent. of nitro-glycerine will now convert the compound into a powerful
explosive; or the proportion may be increased at pleasure up to fifteen per cent, or
even more.
I do not limit myself to the foregoing statement of ingredients, or to the par-
ticular mode described of forming and applying the varnish, cement, or coating.
The statement is only one of a large number of formulas that I might give, to all of
which my Invention would equally apply; in fact, it will be readily seen that the
variations in the substances employed and in the manner of preparing them may be
made almost numberless; but with all variations my Invention demands one thing,
to wit: that the grains or particles of the dry mixture shall be coated, cemented,
varnished, or smeared with some combustible substance offering resistance to

page_text: absorption of nitro-glycerine and of water, and at the same time it must be capable
of bearing any ordinary degree of heat to which the resulting compound may be
exposed in transporting or keeping.
I have found that many resinous gums and various bituminous substances may
be used for the varnish or cement herein mentioned, but most of them are
objectionable on account of high cost or otherwise. Sulphur alone may be used,
and will form a very good varnish or cement, or, on the other hand, it may be
omitted entirely. Some very volatile varnishes might be applied cold to the dry
mixture or certain of its parts, and would answer the purpose I have sought to a
greater or less extent.
The ingredients which form the coating, varnish, or cement may be applied
without first melting them. To do this I first grind each of the materials of the
dry mixture; then leaving out the carbon I mix all the others together and proceed
to lieat them well, all the time stirring, and continue until the whole is thoroughly
varnished, cemented, or coated. While the mixture is cooling the stirring must be
carefully continued until the grains cease to adhere to each other; then add the
pulverized carbon, which must be perfectly dry, mix well, and afterwards put in
the nitro-glycerine. When carbon is used that is not porous or absorbent it is not
necessary that it should be varnished, cemented, or coated. In that case it may
only be necessary to varnish, cement, or coat the nitrate of the mixture.
The aggregation of the small or dust-like particles of the dry mixture into grains
of suitable size to form a powder, which results from the cementing process, is a
very material part of my Invention, as it renders the grains more irregular in forın,
and facilitates the decomposition of the mass.
While, as before stated, the dry mixture may not be entirely non-absorbent after
it has been treated by my varnishing, cementing, or coating process it is sufliciently
so to mainly counteract the absorption of the nitro-glycerine, as well as to check
the tendency to deliquesence; I therefore terin the treated dry mixture "non-
absorbent" in contra-distinction to such absorbent mixtures as have heretofore been
used in this class of powder.
The explosive compound made according to my Invention is exploded sub-
stantially in the same manner as any other of the so-called nitro-glycerine
powders.
CLAIMS.
First. A powder or explosive compound consisting of particles or grains of a gas
producing substance or substances, which are first rendered non-absorbent by
coating, cementing, or varnishing the grains or particles, and subsequently rendered
explosive by the incorporation or admixture with said grains or particles of nitro-
glycerine prepared and applied substantially as above described.
Second. In the manufacture of explosive compounds I claim the process of coating,
cementing, or varnishing the particles which compose the dry mixture with a non-
absorbent substance, and subsequently adding the nitro-glycerine, substantially as
specified.
Third. An explosive compound composed of dust-like or pulverulent particles of
combustible substances aggregated into grains by stirring and cementing, and
rendered explosive by the addition of nitro-glycerine.
ง
In witness whereof, I, the said Egbert Judson, have hereunto set my hand
and seal, this Second day of November in the year of our Loril One
Witnesses,
GEO. H. STRONG.
JOHN L. BOONE.
EGBERT JUDSON. (L.S.)