IMPROVEMENTS IN TREATING FATTY AND OILY SUBSTANCES
Year: 1857

page_text: LETTERS PATENT to Benjamin Chew Tilghman, of Philadelphia, United
States of America, for the Invention of "IMPROVEMENTS IN TREATING
FATTY AND OILY SUBSTANCES."
Sealed the 14th July 1857, and dated the 2nd May 1857.
PROVISIONAL SPECIFICATION left by the said Benjamin Chew Tilghman
at the Office of the Commissioners of Patents, with his Petition, on the
2nd May 1857.
I, BENJAMIN CHEW TILGUMAN, of Philadelphia, United States of America,
do hereby declare the nature of the Invention for "IMPROVEMENTS IN TREATING
FATTY AND OILY SUBSTANCES," to be as follows:-
My Invention consists in a method of treating fatty and oily substances
(whether neutral fats or fat acids) by sulphurous acid, so as to render them
more hard and solid, and improve them for the manufacture of candles and
soap. The fatty substance is exposed to the action of sulphurous acid at an
elevated temperature until the desired effect is produced. The application of
pressure above that of the atmosphere increases the rapidity and completeness
of the action;, large surface of contact and agitation of the acid and fat' is also
beneficial. I find that the addition of a small quantity of oxide of copper or
other suitable substance is useful in preventing the forination of sulphuretted
products in the fat, which would be injurious in the subsequent process of
distillation; mixing the acid gas with vapor of water lias also in some "cases

page_text: been found beneficial. The addition of oxide of copper may also be usefully
made to the fat acids, prepared in the usual way, by the action of sulphuric
acid, to purify them from sulphuretted products. Sulphurous acid may be
used either in the state of gas, solution in water, or condensed into a liquid; or
instead of using it directly, the same effect may be produced by using the
well-known chemical agents capable of evolving it during the operation.
Concentrated sulphuric acid, mixed with fat and heated, evolves sulphurous
acid, and is already used in the treatment of fats, but has the disadvantage of
partly charring and destroying them. I have found that by using diluted
sulphuric acid, and operating at a high temperature under pressure, sulphurous
acid is evolved, and the hardening effect is produced without a destructive
action on the fat. After the operation of the sulphurous acid is completed, tho
fatty substanco is to be washed, and may either be distilled, or treated with
chloride of lime, or any of the usual bleaching agents.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Benjamin Chew Tilghman in the Great Seal Patent Office
on the 2nd November 1857.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, BENJAMIN
CHEW TILGHMAN, of Philadelphia, United States of America, send grecting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Second day of May, in the year of our Lord One
thousand eight hundred and fifty-seven, in the twentieth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the
said Benjamin Chew Tilghman, Her special licence that I, the said Benjamin
Chew Tilghman, my executors, administrators, and assigns, or such others
as I, tho said Benjamin Chew Tilghman, my executors, administrators, and
assigns, should at any time agree with, and no others, from time to time
and at all times thereafter during the term therein expressed, should and
lawfully might make, use, exercise, and vend, within the United Kingdom
of Great Britain and Ireland, the Channel Islands, and Isle of Man, an
Invention for "IMPROVEMENTS IN TREATING FATTY AND OILY SUBSTANCES," upon
the condition (amongst others) that I, the said Benjamin Chew Tilghman,
my executors or administrators, by an instrument in writing under my, or
their, or one of their hands and seals, should particularly describe and
ascertain the nature of the said Invention, and in what manner the same
was to be performed, and cause the same to be filed in the Great Seal

page_text: Patent Office within six calendar months next and immediately after the date
of the said Letters Patent.
NOW KNOW YE, that I, the said Benjamin Chew Tilghman, do hereby
declare the nature of the said Invention, and in what manner the same is
to be performed, to be particularly described and ascertained in and by the
following statement thereof, that is to say :-
My Invention consists of a method of treating fatty and oily substances
(whether neutral fats or fat acids) by sulphurous acil, so as to render them
more hard and solid, and improve them for the manufacture of candles and
soap. The fatty substance is exposed to the action of sulphurous acid at an
elevated temperature until the desired effect is produced. The application of
pressure above that of the atmosphere increases the rapidity and completeness
of the action; large surface of contact and agitation of the acid and fat is also
beneficial. I find that the addition of a small quantity of oxide of copper is
useful in preventing the formation of sulphuretted products in the fat, which
would be injurious in the subsequent process of distillation. Sulphurous acid
may be used either iu the state of gas, solution in water, or condensed into a
liquid. Concentrated sulphuric acid, mixed with fat and heated, evolves
sulphurous acid, and is already used in the treatment of fats, but has tho
disadvantage of partly charring and destroying them. I have found that by
using diluted sulphuric acid, and operating in close vessel's at a temperature
and pressure sufficiently high to cause the evolution of sulphurous acid, the
hardening effect is produced with very little destructive action on the fat.
In putting my Invention in practice I proceed as follows:-A convenient
quantity of the fatty substance is heated up to 500° Fahrenheit in a vessel of
enamelled cast iron, and the sulphurous acid gas is passed through it from a
pipe perforated with numerous holes for about 4 hours, steam is then blown
through the fat until the sulphurous acid is disengaged, it is then cooled and
washed with water, and may subsequently be manufactured by any of the
usual processes of distillation, acidification, saponification, pressing, or moulding.
The sulphurous acid may be obtained by the burning of sulphur or pyrites, by
heating a mixture of sulphuric acid and charcoal, or by any other known
method. As it is desirable to use the gas pure and unmixed with other gases
or vapors, it. is convenient first to make a solution of sulphurous acid (obtained
from any source) in water by a system of Wolf's bottles, or coke columns, or
other known means, and then to evolve the sulphurous acid gas as wanted by
heating this solution in a close vessel. The gas properly separated from
aqueous vapor is forced in numerous streams of bubbles through the fatty
matter at the proper beat, and thence goes into a condenser to separate any

page_text: volatilized fat, and finally escapes into the coke column or other apparatus,
where it is re-absorbed by water to be used in another operation: Of the
sulphurous acid contained in a suitable gas holder may be forced by pumps or
by pressure to bubble through the fat and thence to pass into another gas-
holder to be reused. I prefer to operate at the temperature of about 500°
Fahrenheit, because the action takes place quickly at that heat without the
volatilization of the material being inconveniently great; but the process may
be performed at temperatures not greatly exceeding 212° Fahrenheit, but
with proportionally decreased advantages. The time necessary to produce the
maximum hardness increases greatly as the heat is diminished. At 550°
Fahrenheit about 1 hours is, sufficient, but the fatty substance volatilizes
inconveniently at this heat. I have obtained good results in about 4 hours at
500° Fahrenheit, in about 7 hours at 450° Fahrenheit, in about 14 hours at
400° Fahrenheit, and in from 24 to 30 hours at 350° Fahrenheit. At still
lower temperatures a still longer time is required. The color of the products
is less apt to be darkened at the lower than at the higher range of
temperatures, particularly when acid or partly acid fats are treated. If the
surface of contact of the gas and liquid fat be artificially increased by any of
the known devices the action proceeds more rapidly. If the operation is
continued too long a time at any given heat the fatty substance appears to lose s
some of its previously acquired hardness. Vessels of stoneware or of well
enamelled cast iron answer best, as they resist the action both of the fatty
substance and of the acid gas; copper is next to be preferred as a material,
and it is more convenient for large vessels, though it is somewhat acted upon
by the sulphurous acid, especially in parts not covered by the fatty substance.
In the process of hardening fat acids by sulphurous acid there occurs a
formation of a sulphuretted compound, which is injurious in the subsequent
process of distillation.
One part of my Invention consists in a mode of preventing or remedying
this by the use of oxide of copper. Before Before applying the sulphurous
acid gas I add to the fat acids a quantity of oxide of copper, preferably
in the form of copper soap. The higher the heat used in the operation
and the longer it is continued the greater seems the formation of the sul-
phuretted impurity, and the larger the quantity of oxide of copper needed to
prevent or destroy it. I have found that in operating at about 500°
Fahrenheit for 4 hours oxide of copper equal to about 2 to Too of the
weight of the fat is sufficient; in operating at 450° Fahrenheit for 7 hours
about 30 too of the weight of the fat, and at 400° Fahrenheit for 14
hours
too of the weight of the fat. At the end of the operation the

page_text: copper is found precipitated as a black powder, which may be reconverted
into oxide and reused. The copper soap may be made by heating finely
powdered oxide of copper in 5 times its weight of fat acid for 5 or 6 hours to
350° Fahrenheit, with constant stirring, it is then allowed to settle and the
clear portion poured off; its contents of oxide of copper is then ascertained by
any of the well-known means of analysis, and a proportionate quantity of the
soap is to be used as above directed. In distilling fatty substances in a
current of sulphurous acid gas the sulphuretted compound does not appear in
the distillate, which, though sensibly hardened, is not so much so as the fats
treated as above described, and consequently I do not prefer this mode of
operation.
In the process of hardening neutral fats by sulphurous acid no oxide of.
copper is needed, and the principal thing to be guarded against is the darkening
of the colour of white fats, such as tallow, during the operation, from the
admixture of air or free oxygen with the sulphurous acid gas. A very
small
quantity of free oxygen in the gas will render the fat of a dark red color, and
therefore the apparatus should be carefully swept clear of air, by letting the gas
evolve for a considerable time before passing it into the heated fat. The gas
should also be well washed in water when necessary to free it from any trace
of vapors of sulphuric acid, which would tend to discolor the fat. I have
found it convenient to test the purity of the gas before using it by passing a
stream of it by a glass tube into a small quantity of tallow heated to 500°
Fahrenheit in a glass flask; if the tallow remains unreddened for 15 minutes at
500° Fahrenheit the gas is pure enough for use. Another source of darkening
of color is the action of metallic vessels. When copper vessels are used they
should be well cleaned from oxide, and I prefer that they should be filled quite
full, and the upper part be lined with stoneware or enamel, so that the copper
shall not be anywhere exposed without being covered by the liquid fat. The
fat should be pure and neutral, and free from any mixture of rancid or acid
fats. Old rancid and oxidized fats generally become darkened by the applica-
ation of sulphurous acid at high temperatures, but I have found that in some
cases such fats lose this property by being previously heated for some time to
about 500° Fahrenheit, the air being excluded, and they may subsequently be
treated by sulphurous acid without becoming darkened, consequently I' prefer
to beat the fat to 500° Fahrenheit before admitting the acid gas. Some fats,
such as palm oil, often contain free fat acids, and if acted upon in this state by
sulphurous acid will become more or less darkened and sulphuretted, but if
the fat acid is previously separated by distillation the residual neutral fat

page_text: stands the treatment better. The addition of a suitable quantity of oxide of
copper, proportionate to the amount of fat acids present, will prevent the
sulphuretting action of the gas upon such partly acid fats. The process of
hardening by sulphurous acid is applicable not only to solid but also to liquid
and semi-liquid fatty substances, whether acid or neutral, from which it is
desired to separate the solid matter, as the quantity obtainable from them by
pressing is thereby increased, and the liquid portion is more thin and fluid.
The oleic and margaric acids coming from the cold and hot presses in the
ordinary stearic manufacture may be thus treated, whether the original fatty
substance has or has not been previously treated with sulphurous acid.
The effect of the treatment by sulphurous acid upon tallow is to make it
more hard and dry, it solidifies more quickly, and its point of fusion is more
sharply defined. Analagous effects are produced upon other fatty substances
in various degrees according to their nature. Soaps made from fatty
substances which have been treated with sulphurous acid aro harder than
common.
In distilling fatty substances which have been treated with sulphurous acid
I use a cast-iron still. When operating upon neutral fats and fat acids with
sulphurous acid in close vessels under a pressure of several atmospheres, I
have found that tho hardening effect is produced in a shorter time and at
lower heats than would have been required at ordinary atmospheric pressure.
I bave used the sulphurous acid both dissolved in water and in the state of dry
gas, and find the latter more efficient. Owing to the practical difficulties of
working with acid and corrosive substances in close vessels at elevated
temperatures and pressures, I prefer the plan of working at or about ordinary
atmospheric pressure.
Having thus described the nature of my Invention, and the best means I
am acquainted with of performing the same, I wish it to be understood that I do
not claim generally the process of hardening fatty substances by sulphurous acid,
as I am aware that this has been before proposed, but in such cases the heat
employed has been under or about 212° Fahrenheit. Now, I have found that
the hardening effect of sulphurous acid is very greatly increased by causing it
to act upon the fatty substances at more elevated temperatures, preferring
from about 350° Fahrenheit to 550° Fahrenheit, but which may be varied
from a little above 212° Fahrenheit to above the distilling point of the fatty
substance, and it is to this modification of the process that this part of my
claim extends and is confined. I am also aware that it has been before
proposed to decompose fatty substances and soaps into fat acids, and to purify

page_text: fatty substances from mucilage, gelatin, &c. by means of sulphurous acid, and
also to subject fatty substances at elevated temperatures to the action of strong
sulphuric acid, whereby sulphurous acid is generated in the fat itself, and I
wish it to be understood that I make no claim to any of the above processes.
I claim the hardening of acid and neutral fatty substances by subjecting
them to the action of sulphurous acid at elevated temperatures, either with or
without pressure, as above described.
. I also claim the use of oxide of copper to remove from fat acids the
sulphuretted impurity produced therein by treatment with sulphurous acid, as
abovo described.
In witness whereof, I, the said Benjamin Chew Tilghman, have here-
unto set my hand and seal, this Second day of November, in the year
of our Lord One thousand eight hundred and fifty-seven.
Witness,
GEO. PITT.
B. C. TILGHMAN. (L.S.).