IMPROVEMENTS IN THE MANUFACTURE OF SOAP
Year: 1881

page_text: LETTERS PATENT to Alfred Julius Boult, of the Firm of Wm. P. Thompson
and Company, Agents for Foreign Patent Solicitors, of 323, High Holborn,
London, in the County of Middlesex; 6, Lord Street, Liverpool, in the County
of Lancaster, and Berridge Street, Leicester, in the County of Leicester,
Engineer and Patent Agent, for an Invention of IMPROVEMENTS IN THE
MANUFACTURE OF SOAP." A communication from abroad by Charles S.
Higgins, of Brooklyn, New York, United States of America.
66
COMPLETE SPECIFICATION filed by the said Alfred Julius Boult at tho
Office of the Commissioners of Patents on the 11th June 1881.
ALFRED JULIUS BOULT, of the Firm of Win. P. Thompson and Company, Agents
for Foreign Patent Solicitors, of 323, High Holborn, London, in the County of
Middlesex; 6, Lord Street, Liverpool, in the County of Lancaster, and Berridge
Street, Leicester, in the County of Leicester, Engineer and Patent Agent.
"IMPROVEMENTS IN THE MANUFACTURE OF SOAP." A communication from abroad
by Charles S. Higgins, of Brooklyn, New York, United States of America.
It is well known to those skilled in the art to which my Invention or discovery
pertains that soap is a detersive compound formed by the union of a fat or oil and
an alkali, and that its chief uso is for its cleansing properties, the result of its
action (and the slight excess of alkali in it) upon the grease which holds the dirt
on soiled textile fabrics and the skin.
In the manufacture of hard soaps the alkali generally used is a soda and the
acid, that of an animal fat or oleate. For soft soaps the alkali most suitable is a
potash and the acid that of a vegetable or fish oil. My Invention relates more
particularly to a hard soap or that kind which is usually sold for laundry purposes
in cakes or bars.
It must be borne in mind in understanding the scope of my Invention that the
mere mixing of a fat or oil and an alkali does not make a soap. It is nccessary to
have water present in sufficient quantities to allow the process called saponification.
Common animal fat or tallow contains an oloate of the oxide of glyceryl. In the
saponifying process the oleic acid of the fat seeks to leave the weak base of the

page_text: oxide of glyceryl and to unite with the stronger base of the soda; this is done by
furnishing water to form a hydrate for the glyceryl, upon receiving which it gives
up its acid to the soda.
Inasmuch as, other things being equal, the use of soap in a community increases
in amount as its cost is lessened, it becomes an important consideration to furnish
soap at as cheap a price as is consistent with the attainment of the necessary
qualities in the soap.
There are substances other than fats and oils which are capable of union with
free alkalies, and produce when so treated a viscid detersive compound, having
properties similar to those in fat made soaps. Most soaps for common laundry and
household purposes are yellow or brownish in color. This is due to the use of
rosin in the manufacture of soap. It has been long well known that rosin is one
of those substances which are capable of being saponified by a free alkali so as to
form a detersive compound valuable for cleansing purposes when combined with a
fat made soup. The rosin has in its composition three distinct bodies of acid
properties, vi, sylvic, pinic, and colopholic acids; and these, though each is
insoluble in pure water, are all capable of combining with alkalies and dissolving
in alkaline solutions.
It a toilet soap the use of rosin is not desirable, but in a soap for household and
laundry purposes it is obvious that if rosin, a cheap article, can be made to tako
the place of a portion of the higher priced fat and produce similar results a great
saving in price both to manufacturer and consumer can be effected. Another
advantage of tho use of rosin is, that while a soap of pure animal fat or tallow
quickly dries to an extent not desirable, and becomes brittle by mere exposure to
air, the introduction of rosin prevents this undue brittleness.
Prior to my Invention the amount of rosin which it was found desirable to
incorporate in a hard soap was limited, the usual amount being only about 600
pounds of rosin to 2,000 pounds of fat in a mixture saponified by, say, 150 pounds
of soda lye at a strength of 20°, or about one fourth rosin. If a larger proportion
of rosin was used the amount of water absorbed rendered it soft and pasty and
prevented it from hardening so as to be durable, or adapted to be framed and cut
into cakes and bars.
I have discovered a process by which I am enabled to incorporate into the hard
soap a much larger proportion of rosin, thereby availing myself of its cheap
detersive properties, and at the same time producing a soap which is full as hard
and substantial (if not more so) as the usual hard, soap made in greater part of
fat. The method by which I produce this result is as follows:-For a cheap
laundry soap I take of prime tallow or équivalent fat, say, 10,000 pounds, which is
saponified in the usual mode with a caustic soda alkali of, say, 30° strength.
After the first or "grease" change I add an equal quantity, viz., 10,000 pounds of
clear rosin, which is likewise saponified in the usual manner; about 6,000 pounds
of caustic soda at a strength of 30° being used in the whole. Upon the completion
of the saponifying process, and while the compound is in a hot and fluid state,
before fraining, I add to the soap body a quantity of crystalized stearic acid of
commerce, equal in amount to about (two) 2 per cent. of the bulk of the body to
which it is added, or about threc per cent. of stearine, the substance in either case
being in a heated and fluid state. This is added gradually while the soap is hot,
and it is thoroughly "crutched" into the body, which is then "framed
in the
usual manner; the result being that it solidifies into a hard and useful soap, having
in its composition a resinous detersive, equal in amount to the fatty detersive,
instead of only one third or one fourth as much as heretofore. This soap preserves
its quality and hardness better than many fat made soaps, and does not become
unduly dry and brittle. It also possesses this advantage, viz., in most of the
laundry soaps used a large portion of the soap is wasted because of its solubility,
or dissolving faster to a greater extent than is required for the strictly detersive
purposes, but the soap produced by the process I havo described lasts better and
longer besides being cheaper.

page_text: I am aware that stearine or other combinations of stearic acid have been
heretofore used in making soap, but their use, prior to my Invention, was during
that portion of the process before the saponification was completed, and the stearic
acid in those instances left its base and united with the alkali undergoing a process
of saponification, but in the process above described and invented by me the stearic
acid is added after the saponification has taken place, and after the alkaline-base
has united with the fatty and resinous acids, thereby effecting results entirely
different from those cases where the stearate was added prior to the saponification.
I have described a very cheap made soap,.but .in the higher grade of laundry
soap the proportion of rosin may be lessened, still using the same amount of stearic
acid or stearine.
Having now described this Invention, and the method of performing the samo, I'
wish. it to be understood that what I desire to claim by Letters Patent is,-.
First. The within described process of making soap, viz., the saponification of
fats and resins, and the subsequent solidifying the same by stearic acid or stearine,
substantially as described.
Second. As a new article of manufacture, a rosin soap composed of tallow or its
equivalent, rosin, a caustic alkali, and stearic acid or stearine, in substantially' the
proportions specified.
.
Third. As a new composition of matter, a soap composed of saponified tallow,
saponified rosin, and unsaponified stearic acid or stearine, substantially as and in
the proportions described.
Fourth. The use in the manufacture of rosin soap, of stearic acid or stearine at a
period subsequent to the saponification of its acid ingredients, substantially as
described for the purpose of solidifying the saponified rosin.
In witness whereof, I, the said Alfred Julius Boult, have hereunto set my
hand and seal, this Eleventh day of June, in the year of our Lord One
thousand eight hundred and eighty one.