AN IMPROVED METHOD TO PREPARE EXPLOSIVE MATTER
Year: 1880

page_text: LETTERS PATENT to Albert Hellhoff, Artillery Officer, of Mayence, Grand
Duchy of Hesse, for an Invention of "AN IMPROVED METHOD TO PREPARE
EXPLOSIVE MATTER."
PROVISIONAL SPECIFICATION left by the said Albert Hellhoff at the
Office of the Commissioners of Patents on the 7th July 1880.
ALBERT HELLHOFF, Artillery Officer, of Mayence, Grand Duchy of Hesse.
"AN IMPROVED METHOD TO PREPARE EXPLOSIVE MATTER."
If concentrated nitric acid, by preference of a specific gravity of 1·5, be gradually
added to tar oils, heat will be generated, and the mixture will grow turbid in
consequence of the nitrification of the separated volatile substances under
treatment.
With the object to not produce a waste of material, it is advisable to well stir the
mixture, and to interrupt the addition of nitric acid, or to cool the mixture in a
water bath or otherwise when respectively until a maximuin of one or more species
of nitrated products is in a state to precipitate. The oil residues may then be
drawn off and treated with nitric acid as befor, under higher temperatures, without
loss, whilst the nitrified first precipitates are washed and dried.
The products thus obtained, either by a continual or consecutive treatment with
nitric acid, will produce in due mixtures with salts, which, by decomposing, liberate
oxygen, by preference with the nitrites of alkalies, chlorate of potash, or with nitric
acid, an explosive compound of a very high socalled Crisant effect.
If it is intended to simplify the manufacture, certain extracts of the tar oils may
be made at the beginning of the process by distillation or otherwise, and then the
distilled or otherwise produced products, as well as the residues, are treated with
nitric acid, precipitated, washed, and dried, and finally used as compounds for
explosive matter.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, and of
an Order of the Lord Chancellor, filed by the said Albert Hellhoff in tho
Great Seal Patent Office on the 19th January 1881.
ALBERT HELLHOFF, Artillery Officer, of Mayence, Grand Duchy of Hesse.
"AN IMPROVED METHOD TO PREPARE EXPLOSIVE MATTER."
This Invention constitutes an important progress in chemical and in technical
respect, as by means of the same new and eminently useful substances may bo
produced from certain residual-matorials which have hitherto been but little
utilized. Especially for blasting and other similar purposes, these-new substancos
are of great value, as they form an element for the composition of explosives, in
which a high degree of efficiency is combined with extreme cheapness, and which, on
account of these qualities, may with advantage be applied even for the generation of
power hitherto produced by the agency of man or of engines.
The first part of the Invention consists in a method for the manufacture of nitro-
derivatives from crude taroils. For this purpose I have proceeded as follows:-
One part by weight of crude oil was mixed with two parts by weight of nitric
acid (common acid of commerce of a specific gravity of about 1-35), the acid being
allowed to run slowly from a dripping-apparatus into the oil, which was constantly
stirred. For the purpose of conducting the nitrifying process with certainty, the
mixing-vessel was efficiently-cooled, so that no increase of temperature took place.
The addition of the acid having been completed, the mixture, while being.constantly
stirred, was slowly heated to about 50° centigr., until pale red vapours issued from
its surface. At the same time a strong chemical reaction began to present itself.
As soon as the vapours commenced to assume a dark red colour and to become thick,
three further parts by weight of tar-oil were added slowly under constant stirring,
whereby a partial burning or super-oxydation of the oil (which would otherwise
take place) is avoided, whereas the excess of acid contained in the mixture is
utilized in a practical manner. By adding the oil gradually the liquid is main-
tained at the temperature requisite for the nitrification. The end of the process was
indicated by a rather speedy decrease of temperature.
For the purpose of ascertaining whether the nitrifying process was going on in
the proper manner, samples were taken from time to time and treated with water.
In case the product was completely and properly nitrified, it separated from the
water and sunk to the bottom of the test-glass as a liquid substance of dark ruby-
red colour, and of a specific gravity slightly exceeding 1.0.
A black colour
indicates that the process has been too intense, and that a partial burning has
taken place. The product is finally washed out with a large quantity of water.
As it appeared advantageous for certain purpose to obtain a product of a higher
degree of nitrification, 1 adopted the following course :-
The nitrified product of the first process is slowly mixed with concentrated nitric
acid in the proportion of one part by weight of the former to one part and a half of
the latter, the mixture being constantly stirred and cooled. The said product
dissolves with facility in the acid, the solution being of very dark brown colour.
The mixture is thereupon exposed to a temperature of 40° centigr., which causes it
to separate in a. light coloured upper layer and a darker lower one. The said
temperature being, maintained, the reaction progresses, the substance forming. the
bottom layer rises through the upper layer in bubbles, which, thoreupon descend
again as dark red and transparent drops. The bottom layer is thereby gradually
converted into a semi-pellucid mass of syrup-like consistency. After due washing
with water this mass forms the final product. The same is heavier than the
nitrified product first obtained, and after having been washed with water it is of a
colour approximating to orange.

page_text: As numerous experiments have proved, the described process may be modified in
various points. Thus, for instance, concentrated acid may, as in other nitrifying
processes, be used from the beginning by adding the same to the oil, while tho
temperature requisite for the nitrification is regulated by the manner of adding tho
acid. The products resulting from this mode of proceeding however often proved to be
of improper constitution, while dangerof explosion was incurred, whereas by inverting
the process and allowing the oil to run slowly into the concentrated acid (instead of
adding the acid to the oil), very satisfactory results were obtained. The heat
increased very slowly up to the temperature necessary for the nitrification, and the
acid did its full work without requiring any additional heating of the mixture.
This mode of manufacture gave products of high degree of nitrification, but is
proved to be moro expensive than the first described one. The substances were
employed in this case in the proportion of 100 parts by weight of oil on 150 parts
of concentrated acid.
The experiment was also made to add sulphuric acid to the nitric acid used in
the process,
but the result was not favourable in respect to the quantity of product
obtained, as probably a partial burning of the oil had taken place. The same is to
be said with regard to the use of salt-petre (nitrate of potash or of soda) together
with sulphuric acid.
On account of the great number of different undeterminate substances contained
in the crudo tar-oils, and of the probable difference of temperature required for the
nitrification of the same, the thought suggested itself to me to extract some of the
components of the oil by distillation at certain fixed temperatures, and to treat these
components separately.
An extract was, for instance, made from the crude oil by distilling at 160° centigr.
The same was perfectly clear, colourless, and of a specific gravity of somewhat less
than 1-0. If this extract is treated according to the above described method, nitro-
derivatives are obtained which are conspicuous in respect to the greater quantity
yielded and on account of the normal course of the process.
As the tar-oils obtained from different sources present differences in their com-
position, which are often not inconsiderable, it is a matter of course that the
aforesaid proportions of the mixture and the temperatures to be observed cannot in
all cases be strictly adhered to. To any person versed in the special part of
chemistry, to which the Invention relates, the necessary modifications of the process
required in any particular case will however indicate themselves from the
explanation and the general rules of proceeding laid down in the foregoing.
Besides the crude tar-oil from mineral coal, the products of the distillation of all
other kinds of tar, such as the tars obtained from lignite, from wood, from the
manufacture of oil-gas, &c., are adapted for my process, as they are in general of a
similar composition as the former. Also with petroleum and with the residues of
the manufacture of mineral oil, careful experiments, attended with very satisfactory
results, were made according to the foregoing prescriptions.
The second part of my Invention relates to the producing of explosive matter
from the nitro-derivatives obtained by the described process. For this purpose the
Ditrified products were washed with a weak solution of caustic soda, so as to purify
them from any burnt parts which would be prejudicial to the explosive effect.
The substances thus prepared were mixed with various materials containing oxygen,
by preference with any nitrate of an alkali, chlorate of potass, nitrate of ammonia,
or with the most concentrated nitric acid of 1.52 specific gravity.
From all these mixtures explosives of great energy resulted, which latter proved
to be directly proportionate to the amount of oxygenated substances added. The
highest effect was obtained by nitric acid, in which all the nitro-derivatives were
soluble under slight development of heat. In case products obtained from light oils
were employed the greatest Crisant power (or velocity of explosion) resulted from a
mixture of ono part by weight of the nitro-derivative with two parts by weight of
the most concentrated nitric acid, whereas the nitro-derivatives from heavy oils

page_text: require upon one part about two parts and a half of the acid if the highest Crisant
effect is to be attained.
When the substances of a higher degree of nitrification, described in the foregoing,
are used, the quantity of acid to be added may be reduced by one half, part by
weight. These substances present moreover the advantage that when being mixed
with acid the mixture will not become as hot as when the less nitrified products are
used.
After having found by experiment the necessary quantity of nitric acid to be added,
I calculated the amount of other oxygenated substances which would be required
instead of the acid for producing the same effect as the latter, this calculation being
...based on the chemical constitution of the nitric acid and of the said oxygenated
substances, and on the proportions in which oxygen which may become free is
contained in the one and the other.
All the explosive materials prepared according to such calculation proved to be of
a highly Crisant effect. The most prominent in this respect were however those
obtained by the application of nitric acid, and in fact these substances are superior
in their Crisant power to dynamite. The said particular quality, i.e., the faculty of
exploding with great velocity, may however be diminished by adding a smaller
quantity of oxygenated substances.
Having thus described the nature and object of my Invention, and the manner in
which it is to be carried out in practice, I hereby claim,-
1. The new nitro-derivatives produced by nitrifying any kind of crude tar-oils,
--substantially_as herein before specified.
2. The new nitro-derivatives produced-by-nitrifying any product of fractional
distillation of any kind of crude tar-oil, substantially as described.
3. The new nitro-derivatives obtained by nitrifying petroleum or other mineral
oils, or the residue from the manufacture of any mineral oil, substantially as
specified.
4. The process of nitrifying crude tar-oils, distilled extracts of the same, petroleum,
or other mineral oils, or residues from the manufacture of mineral oils, by subjecting
the said substances to the action of nitric acid, with or without sulphuric acid,
or of nitrate of potass or soda, with sulphuric acid, substantially as and for the
purpose described.
5. The new explosive substances produced from the nitro derivatives of crude
tar-oils or their distilled extracts of petroleum, of mineral-oils, or of the residues
from the manufacture of mineral oils, by mixing such nitro-derivatives with
concentrated nitric acid or any nitrate of an alkali, chlorate of potass, or nitrate of
ammonia, or other suitable oxidizing agents, substantially as herein before described.
In witness whereof, I, the said Albert Hellhoff, have hereunto set my
hand and scal, this Fourth day of January, in the year of our Lord One
thousand eight hundred and eighty one.
AT DEDT TILLHORN