Improvements relating to Explosive Compounds.
Year: 1890

page_text: Date of Application, 17th Nov., 1890-Accepted, 20th Dec., 1890
COMPLETE SPECIFICATION.
Improvements relating to Explosive Compounds.
I JOHN SPENCER WALTER of 62 Old Broad Street in the City of London,
Gentleman, do hereby declare the nature of this invention and in what manner the
same is to be performed, to be particularly described and ascertained in and by the
following stateinent :-
These improvements relating to explosive compounds consist in an improved mode
of manufacturing an improved safety explosive.
In carrying out this invention, I first melt, in a suitable vessel, a small quantity
(the proportion will be given hereafter) of crystals of picric acid. In order to give a
start to the melting process, a small quantity of some material such as oil should first
be placed in the vessel, this will have the effect of melting the first few crystals, and
when once the melting has commenced, the picric acid will continue to melt without
any extraneous assistance. To the melted picric acid should then be added fino
sawdust, or any suitable absorbent, such as wood pulp, cotton, bran &c., in such pro-
portions that the absorbent will wholly take up the melted picric acid, so as to be
thoroughly surcharged with the acid. During this part of the process, the temperature
must be carefully watched, and kept below the carbonisation point of the absorbent.
I next dissolve (preferably in a jacketted pan) a quantity of nitrate of potash
(saltpatre) in about its own weight of water. A certain proportion of the surcharged
absorbent is then added to a large quantity of fresh or untreated sawdust in a dry
state, and mixed with it (dry) in any suitable manner, by hand or otherwise. The
misture of sawdust is then added gradually to the solution of nitrate of potash, until
the whole of the mixture has been introduced into the pan. The sawdust, when first
introduced into the pan, will float on the surface of the solution of nitrate of potash,
thereby serving as a cover to the pan, and assisting to retain the heat in the solution.
By degrees, the lower layers of tho sawdust that float on the surface will become
saturated, and will sink to the bottom. The effect of the gradual sinking of the
sawdust will be that every particle of the surcharged sawdust containing the picric
acid will be brought into intimate contact with the solution of nitrate of potash, and
will thereby (to use a homely expression) leaven the whole lump. I may here remark
that it is not essential that surcharged absorbent should be mixed with the fresh or
untreated sawdust. In some instances, it may be preferable to put the absorbent first
into the solution, and then gradually add the fresh or untreated sawdust to the
solution. It is important to mention that the nitrate of potash above referred to is
the common commercial form of the chemical, consisting of large hydro-charged
crystals.
The mixture of the sawdust with the nitrate of potash having been satisfactorily
effected, the second stage of the process is then complete, and the combination of
ingredients in the pan should be allowed to cool down to about 200° Fahr.
1 next introduce into the mixture a proportion of flowers of sulphur. This
ingredient is introduced in a particular manner. The mixture produced at the
2nd stage when it is left to cool, is a viscid mass of about the consistency of thick
porridge, and containing a certain quantity of liquid that is free to drain away from.
the mass under favorable conditions. The mass in the pan is temporarily pushed to
ono side of the pan, the free liquor being allowed to drain from it into the space thus
formed. The sulphur (which has previously been passed through a fine sieve) is then
introduced into this space, and is mixed with the free liquor until the liquor and the
sulphur form a thick paste, similar to table mustard. The whole mass may then
readily be mixed together with a flat tool, or in any suitable or convenient manner,
and as it cools, it will granulate, providing that the air be admitted to the mass by
cutting the mass in different directions, and breaking up the lumps with an edged
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page_text: tool, such as a trowel or a knife. As soon as the mass has become quite cool and dry,
it will then be ready for the market.
One pound (1 lb.) of picric acid will be absorbed by about twelve ounces (12 ozs.)
of fine sawdust, and two ounces (2 ounces) of the surcharged sawdust will contain about
one ounce four drachms (1 oz. 4 drms.) of picric acid. It is advisable, in some cases,
when the surcharged sawdust is dry and cool, to grind it in a mill, so that the mixture
may be perfectly uniform.
The following proportions may be considered to be a fair standard for all ordinary
purposes of the improved explosive, as manufactured according to the improved
process.
The abovementioned proportions are for ordinary commercial purposes, but where
greater explosive force is required, the percentage of picric acid in the surcharged
sawdust may be increased to two, three, or more times the quantity above specified.
Having now particularly described and ascertained the nature of the said inven
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. The manufacture of explosive compound herein described, and consisting in first
impregnating a suitable absorbent, such as sawdust, with melted picric acid, so that
the sawdust shall be surcharged with the picric acid; second, mixing the surcharged
sawdust with a solution of nitrate of potashi and sawdust, and finally adding flowers of
sulphur, all in the manner set forth.
2. A safety explosive compound composed of pieric acid, a suitable absorbent, such
as sawdust, nitrate of potash, and flowers of sulphur, in or about the proportions
specified.
Dated this 12th day at Novamban 1800
NEWTON & SON,
Agents for the Applicant.