Year: 1899

page_text: Date of Application, 13th June, 1899
Complete Specification Left, 13th Mar., 1900-Accepted, 5th May, 1900
A communication from JAMES FINDLAY TORRENCE SARGENT, of 2128, North
Pennsylvania Street, Indianapolis, County of Marion, State of Indiana,
United States of America, Manufacturer.
I, ALFRED JULIUS BOULT, of 111, Hatton Garden, in the County of London,
Chartered Patent Agent, do hereby declare the nature of this invention to be as
follows:-
This invention relates to an improved process for producing nitro-explosives.
In the preferred way of manufacture starch is subjected to a temperature exceed-
ing 1000 Centigrade but not exceeding 140° C. in order to dry it, and while hot
is put into a closed container and cooled to below 4° C.
One volume of nitric acid of 1.50 specific gravity is then mixed with two
volumes of sulphuric acid, specific gravity 1.84, and the mixture cooled to
below 4° C. Then to each litre of this acid bath is added 200 grammes of the
dried starch previously cooled to below 4° C., and the whole mixed thoroughly by
constant stirring. The mixture is then reduced to a temperature of 4° C. or 6° C.
by pouring it onto broken ice using about 2 pounds of ice for each pound of
sulphuric acid represented. The nitro compound settled in. a mass, with water
adhering, of specific gravity of 1.30. It is separated and the surplus acids saved
for future recovery and use. The nitro-starch mass is washed a time or two
to remove excess of acid, then more water is added and a slight alkaline reaction
produced by adding soda-ash, after which the alkalized mixture is vigorously
boiled for about ten minutes to remove impurities which would interfere with
the explosive qualities and impair the stability of the explosive.
The nitro-starch settles rapidly and admits of washing, draining, etc., with
great ease. This boiling and washing is repeated until all the soluble matters
are removed, then the nitro-starch is dried, which completes the process of manu-
facture.
COMPLETE SPECIFICATION.
An improved Process for producing Nitro-explosives.
A communication from JAMES FINDLAY TORRENCE SARGENT, of 2128, North
Pennsylvania Street, Indianapolis, County of Marion, State of Indiana,
United States of America, Manufacturer.
I, ALFRED JULIUS BOULT, of 111, Hatton Garden, in the County of London,
Chartered Patent Agent, do hereby declare the nature of this invention and in
An improved Process 1or Producing Nitro-explosiv88.
A communication from JAMES FINDLAY TORRENCE SARGENT, of 2128, North
Pennsylvania Street, Indianapolis, County of Marion, State of Indiana,
United States of America, Manufacturer.
I, ALFRED JULIUS BOULT, of 111, Hatton Garden, in the County of London,
Chartered Patent Agent, do hereby declare the nature of this invention and in

page_text: what manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement:-
This invention relates to that class of explosives known as nitro-explosives,
such compounds being bodies in which hydrogen is replaced by NO,, or, as some
times understood, in which hydroxyl (HO) is replaced by NO. The particular
class of bodies in which the base for this explosive is found is that class known
in chemistry as carbohydrates. Heretofore, in the manufacture of carbohydrates,
nitro-compounds it has been customary to take cotton fibre, paper or wood pulp,
or other forms of cellulose or cellulose-related bodies and submit them, after
careful purification, to the action of nitric acid or mixed nitric and sulphuric
acid, whereby these cellulose bodies were converted into nitro-compounds. The
excess of acid was washed away and the operation variously completed.
In the preferred way of manufacture, starch (preferably that of maize) and
without any purification is taken, and submitted to a temperature exceed
ing 100° Centigrade but not exceeding 140° C. whereby the combined or adherent
moisture is driven off; then this dried starch is put while hot into closed con-
tainers and allowed to cool or caused to cool, to below 4° C.
'
A bath of nitric acid and sulphuric acid is then prepared as follows One
volume of nitric acid of as near to 1.50 specific gravity as can be procured is taken
and mixed with this two volumes of sulphuric acid, specific gravity 1.84, the
mixture is cooled to below 4° C. in a suitable cooling apparatus and with each
litre of this acid bath is mixed 200 grammes of the dried starch, previously coofed
to below 4° C. This is allowed to thoroughly mix and the mixture to react for
a few minutes or longer if expedient. The mixture is then poured upon broken
ice, using about 2 pounds of ice for each pound of sulphuric acid represented.
The temperatures of the diluted mixture of acid, nitro-starch and melted ice will
fall to 4° C. or to 6° Q. and no local or general heating will occur.
mixing should be accomplished by continuous stirring. The separation of the
nitro-starch from the surplus acids may now be accomplished by gravity or
centrifugal action. The nitro-compound settles to a mass, with water adhering,
of a specific gravity of 1.30. The original acid mixture had a specific gravity
of about 1.75. The actual specific gravity of the dried nitro-starch is about 1.69,
but when suspended in aqueous liquids of inferior density it settles to a stiff
mass of specific gravity about 1.30, and will not settle if the specific gravity of
the aqueous liquid equals or exceeds that of the mass. For this reason sufficient
=
-
The
water is used to reduce the gravity of the acid residue to below 1.30 and in the
above mentioned procedure it will be seen that the nitro-starch will settle readily
by gravity or centrifugal action. It is separated in either manner and the
residue or surplus acids saved for future recovery and use.
The nitro-starch is washed a time or two to remove excess then more water
is added and soda-ash of a quantity sufficient to produce a slight alkaline reaction
is introduced, said soda-ash usually equalling in weight one to two per cent, of the
weight of the compound, and the alkalized mixture is then vigorously boiled in
a suitable vessel.
The boiling need not exceed more than ten minutes in time and the purpose
of boiling the alkalized medium is to remove impurities which interfere with the
explosive qualities and impair the stability of the new explosive. The nitro-
starch is now a rapidly settling powder of remarkable tenacity and coherence
and admits of washing, draining, etc. with great ease. The boiling process and
washing are repeated until all soluble matters are practically eliminated, and
then the nitro-starch is dried, which completes the process of manufacture. Inas-
much as nitric acid of specific gravity of 1.50 or thereabouts, is not always pro-
curable, nor permitted by transportation companies to be shipped in large
quantities, and also sometimes for economical reasons, it may be necessary or
expedient to modify the acid bath used in the manufacture of this explosive.
This can be done without varying the general process. It is well known that the
office of the sulphuric acid in this bath is to absorb any water that may be present

page_text: in the nitric acid or which is set free in the reaction between the starch and the
nitric acid. Nitric acid may therefore be used of specific gravity of about 1.42
containing about 70 per cent. of anhydrous acid, by increasing the proportion of
Bulphuric acid.
Therefore with nitric acid of specific gravity 1.42 or thereabouts, 5 volumes
of sulphuric acid s.g. 1.84 are used, to each volume of nitric acid s.g. 1.42, and
about 70 grammes of dried starch are used to each litre of the mixture. Or,
nitrate of potassium or sodium as the source of the nitrie radical may be used,
and the hath made of either salt dissolved in sulphuric acid. In this case one
pound of KNO to six pounds of sulphuric acid is taken or one pound of NaNO3
to seven pounds of sulphuric acid, and 70 to 80 grammes of starch are used to cach
litre of the mixture. The general process of nitration is the same as with the
stronger nitric acid, as to temperatures, dryness of the starch and dilution with
water or ice.
Instead of diluting the mixture, after nitration is accomplished, with ice a
container may be employed surrounded by a freezing. mixture or agent, such as
is used in the manufacture of artificial ice, and into this the proper quantity
of water may be put and then the mixture of acids and nitro-starch may be added
at such a rate that the temperature will not rise about 4° C., or to the point
which invites "dangerous chemical action. Such variations of the process' as
above stated are readily seen to be tantamount to each other.
[14
I
My correspondent is aware that nitro-compounds of carbohydrates, and even
of starch itself, have been made heretofore, and that the manufacture of' nitro-
cotton and nitrated wood pulp are established industries. But all past authori-
ties agree that nitro-starch as heretofore' made is an exceedingly unstable com-
pound, subject to spontaneous chemical alteration, and too feeble for, practical
explosives. The cause of this acknowledged instability and general unsatis
factory character is to be found in the processes heretofore used. The usual
process has been to dissolve, starch in strongest nitric acid and precipitate" the
solution with water. Even when the action of the nitric acid has been supplements
by sulphuric acid the character of the prod
product is substantially the same as that of
the product of strong nitric acid alone, by processes heretofore used. The result
ing nitro-compound contains a less or more variable proportion of NO, and is
of a horny and impenetrable character, difficult or impracticable to wash free
from acids and unallowable impurities, and hence unstable. Moreover the dis-
stinct and individual character of the original starch granules is destroyed, and
the microscope reveals irregular fragments or flocculi of the compound. But this
process is unaccompanied by any solution of the starch or nitro-starch, which
latter retains the granular form of the original starch, and no disintegration of
any granules results from the production. of nitro-starch by the above process!
Starch as it occurs in nature is in the form of more or less rounded or angular
granules, visble under the microscope. These granules are composed of an inner
substance called "granulose" and an outer envelope called amylo-cellulose."
This envelope is easily ruptured by heat or chemical agents. The production
of a stable and satisfactory explosive depends as my correspondent has discovered,
upon the maintenance of the integrity of those starch granules and the con-
tinuity of this envelope.
Starch retains, at common temperatures, some 10 or 15 per cent, of moisture,
which may be driven away by exposure to a temperature of 100° Centigrade,
or above, as before stated. This moisture must be dried out before nitration, for
reasons which will now be disclosed.
Even after drying, water is assimilated during the process of nitration as

page_text: which is, at the same time, compatible with a nitrating bath. The absorption of
this water by sulphuric acid is attended with generation of heat. All of these
facts are well known to chemists and form part of the literature of chemistry.
My correspondent has discovered that sulphuric acid in acting as an absorbent of
water, eliminated by the reaction shown, only generates heat to the extent
possible by its combination with water to the point of greatest physical cons
densation, answering to the chemical formula:.
-
explosive.
equation is:
NOW
THIS трасетон,
2 CH + 6 HNO, +3H,SO, = 2 CH, (NO,),0, + 3 (H,SO, 2 H,O).
10
In practice the sulphuric and nitric acids are mixed separately from the starch
and allowed to cool. The heat reaction between the starch and mixed acids is
therefore due alone to the assimilation of water from the starch and its com-
bination with the sulphuric acid.
In chemical works the combination of a molecule of H₂SO, with two mole-
cules of water is stated to be attended with the generation of 9756 heat units.
The above equation, into which three molecules of H₂SO, and six molecules
of water enter, therefore generates three times the heat, of 29268 heat units.
The bodies entering into the reaction are, as stated above, 324 parts of starch
with a specific heat of .53; 378 parts of HNO, with specific heat of .375;--and
294 parts of H₂SO, with specific heat of 343, and it is readily seen that the
reacting bodies are equivalent.in absorption of heat to 414 parts of water. Hence
the rise of temperature, aside from decomposition, would be, according to calcu-
lation, 70° C. Inasmuch as this rise of temperature would result in the destruc-
tion of the reacting bodies, and would be uncontrollable in practice, the process
of diluting the mixture of sulphuric and nitric acids so as to give a calculated
rise of temperature of not over 20° C. has been devised, which practice has shown
that it is fully under control by refrigerating mixtures, and more over the
reacting agents may be reduced to -16° C. without freezing them to a solid
mass, and then the rise of temperature will not carry the reacting materials to
beyond 4° C. which my correspondent regards as the critical temperature for
starch, in practical manufacture: the dilution is accomplished by the general
rule, as follows:-
First: An excess of nitric acid is necessary for a high nitration, and in prac-
tice it is found that twice the theoretical quantity is sufficient. Therefore double-
the calculated quantity on nitric acid is invariably doubled.
Second. Sulphuric acid, aside from its office of assimilating the water set free
in the reaction between the starch and the nitric acid, is practically the only
available diluting agent, for the following reasons: Nitric acid itself, when
used in large excess, tends to dissolve and disrupt the granules of the starch.
As before stated, disruption of the granules causes instability of the product
and is hence objectionable. Sulphuric acid not only does not dissolve or dis-
rupt the granules, but prevents the nitric acid from so doing. Hence it is
perfectly available as a diluting agent."
Calculation shows that when a given quantity of dry starch, double the
theoretical quantity of nitric acid and six times the theoretical quantity
of sulphuric acid" will give a rise of temperature of 20° C., or less.
Hence a bath made according to this understanding will be a practical
bath. With heat generation of 29268 heat units, based on 324 parts of
starch (2CH,0%) this ration of starch, nitric acid and sulphuric acid is equiva-
lent to about 1500 parts of water, hence equal to a rise of somewhat less than 20° C.
in actual temperature. This rise is under perfect control by common frigerific
appliances and permits a nitration to be made without a rise of temperature
10

page_text: to above 4° C. as already specified. The rise of 20° in temperature here men-
tioned must not be confused with a registered temperature of 20° C., since the
latter will be fatal to the nitro-compound.
The actual rise in temperature in the bath during nitration mrst not be to
above 4° C., which my correspondent has discovered is the danger point in.
practical manufacture, as beyond this the granules will begin to disrupt resulting
in an unstable product. In practice the temperature of the bath can be reduced
to a point where the rise in reaction will not carry it above said point. For
instance, the bath being reduced to a temperature of -16° C. the addition of
the starch would cause a rise of about 20° in temperature, which would bring
the bath to about 4° C. actual temperature. Instead of reducing the temperature
of the bath to -16° C. however, the same result can be accomplished by reducing
it to below the danger point and surrounding the nitrating jars with a frigerific
agent capable of absorbing the rising heat so that the actual temperature will not
rise to above said danger point.
Having now particularly described and ascertained the nature of the said
invention, as communicated to me by my foreign correspondent, and in what
manner the same is to be performed, I declare that what I claim is:-
1. The process of producing nitrate of starch which consists in eliminating
the moisture from the starch and subjecting it to a nitrating bath at a temperature
below the point where heat caused by the reaction will rupture the starch
granules, whereby the product consists of granules of the same physical form as
the original starch granules, and its stability thereby insured, substantially as set
forth.
2. The process of producing nitrate of starch which consists in removing the
moisture from the starch by dry heat, reducing its temperature to below the point
where its granules will rupture in the nitrating bath, mixing said starch into
said nitrating bath made and maintained during the operation at a temperature
below said point, and then purifying and drying the same, whereby the product
consists of unruptured granules, and its stability thus insured, substantially
as set forth.
3. The process of making a stable nitrate of starch consisting in removing
the moisture from the starch. then cooling the starch, and then treating said dried
and cooled starch in a nitrating bath at such temperature where rupture of the
starch granules will not occur during nitration; substantially as set forth.
4. The process of producing nitrate of starch consisting in submitting dried
starch to the action of a nitrating bath at or below 4° Centigrade, diluting the
mixture with water sufficient to lower its specific gravity to below 1.30, washing,
neutralizing and drying the product, substantially as set forth.
5. The process of producing nitrate of starch consisting in drying the starch
until practically free from moisture, cooling the same in closed vessels, mixing
the same into a nitrating bath of a temperature maintained during the operation
below 4° C., allowing the starch to macerate, then diluting the bath to not
over 1.30 specific gravity, then washing, neutralizing and drying the nitro-starch,
substantially as set forth.
6. The process of producing nitrate of starch consisting in drying the starch
until free from moisture as nearly as may be, placing the dried starch while hot
in closed vessels, reducing its temperature in said vessels to below 4° C., pre-
paring a bath of nitric and sulphuric acids, reducing its temperature to
below 4° C., mixing said dried starch into said bath while maintaining its
temperature below 4° C., permitting the starch to thoroughly macerate, diluting
the mixture into ice or water in a refrigerating apparatus so that the heat caused
by the reaction between the acid and water shall not cause the temperature to
rise above 4° C., and proportioning the water or ice so that the diluted acids
shall not exceed 1.30 in specific gravity, removing the diluted acids by subsidence
of the nitro-starch and decantation of the acids, washing the greater portion of

page_text: the acids from the nitro-starch, then boiling the nitro-starch with an alkaline
lye sufficient to maintain a distinct alkaline reaction, until soluble matters are
dissolved, washing the nitro-starch with water until soluble matter is practically
eliminated, and finally drying into the finished product, substantially as set
forth.
Dated this 12th day of March 1900.
BOULT, WADE, & KILBURN,
Agents for the Applicant.