AN IMPROVED PROCESS FOR THE MANUFACTURE OF SOAP, CHIEFLY DESIGNED FOR THE RECOVERY OF GLYCERINE FROM THE RESIDUE OF SUCH MANUFACTURE
Year: 1881

page_text: ETTERS PATENT to Henry Harris Lake, of the Firm o Haseltine, Lake,
& Co., Patent Agents, Southampton Buildings, London, for an Invention of
"AN IMPROVED PROCESS FOR THE MANUFACTURE OF SOAP, CHIEFLY
DESIGNED FOR THE RECOVERY OF GLYCERINE FROM THE RESIDUE OF
SUCH MANUFACTURE." A communication from abroad by the Firm of
Benno, Jaffé, & Darmstaedter, of Charlottenburg, near Berlin, Germany,
Glycerine Manufacturers.
PROVISIONAL SPECIFICATION left by the said Henry Harris Lake at the
Office of the Commissioners of Patents on the 9th April 1881.
"
HENRY HARRIS LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London. AN IMPROVED PROCESS FOR THE MANU-
FACTURE OF SOAP, CHIEFLY DESIGNED FOR THE RECOVERY OF GLYCERINE FROM
THE RESIDUE OF SUCH MANUFACTURE." [A communication from abroad
by the Firm of Benno, Jaffé, & Darmstaedter, of Charlottenburg, near Berlin,
Germany, Glycerine Manufacturers.]
This Invention relates to an improved process for the manufacture of soap,
chiefly designed for the recovery of glycerine from the residue of: such
manufacture.
The large quantity of common salt ordinarily contained in spent lye which has
been used in soap manufacture has hitherto prevented the recovery of the glycerine
contained therein, or has permitted the recovery of a very inferior product only,
and to obviate this difficulty it has been sought to transform the common salt into
a salt more easily separated from the spent lye than is the case with the former.
This transformation is however attended by many difficulties.
According to the present Invention I dispense with the use of common salt and
employ in place thereof sulphates of alkaline substances, or some other suitable
salt for separating the soap from the spent lye. I prefer to employ for this purpose
sulphate of soda or of potash whether hydrated or anhydrous, but other salts may
be used instead of the common salt heretofore employed.
The spent lye obtained by means of the said sulphate or other salt is after being
neutralized, filtered with sulphuric acid, and after being purified by some suitable
method, can again be used in the manufacture of soap for effecting the said
separation.
After the sulphates are distilled off or separated glycerine remains, which
contains only a small proportion of impurity and may be refined by the ordinary
methods.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Henry Harris Lake in the Great Seal Patent Office on the
8th October 1881.
HENRY HARRIS LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London. "AN IMPROVED PROCESS FOR THE MANU-
FACTURE OF SOAP, CHIEFLY DESIGNED FOR THE RECOVERY OF GLYCERINE FROM
THE RESIDUE OF SUCH MANUFACTURE." A communication from abroad by
the Firm of Benno, Jaffé, and Darmstaedter, of Charlottenburg, near Berlin,
Germany, Glycerine Manufacturers.
This Invention relates to an improved process for the manufacture of soap, and
is chiefly designed for facilitating the recovery of glycerine from the residue of
such manufacture.
When the soap-liquor has been formed from fatty matter and lye in the manner
ordinarily adopted in the manufacture of soap, that is to say, when the mixture of
soapy solution, glycerine, unspent lye, and the substances derived from the fatty
matter has been made, the separation of the soap from the lye is effected by means
of salts. Soda soap is not soluble in a concentrated solution of common salt,
therefore a quantity of common salt is ordinarily added to the above named
solution, the quantity of such salt being more than that required for complete
saturation; consequently the soap separates in a solid condition and floats upon
the spent lye which is thus produced, such spent lye being mixed with common
salt, glycerine, a small quantity of unspent lye, and fatty matter.
The glycerine cannot be easily separated from the common salt, and the recovery
of glycerine from the spent lyes of soap manufacture in a profitable manner is a
problem yet unsolved even by the transformation of the common salt contained in
the spent lye into some other salt more readily separable from the glycerine, as it
is very difficult to effect this transformation.
Now according to the present Invention I do not use common salt for separating
the soap from the lye, but I employ in lieu thereof an alkaline sulphate salt. The
alkaline sulphates, specially the sulphate of soda, will act upon the soapy liquor in
the same manner as common salt, but there will be no difficulty in subsequently
separating such sulphate from the glycerine.
The spent lye obtained in eliminating the soap by means of sulphate of sodium
has an alkaline reaction, and is therefore first neutralized by the addition of hydric
sodic sulphate; it is then filtered and ultimately evaporated. In the process of
neutralizing the spent lye, the hydric sodic sulphate is transformed into sulphate of
soda by the caustic soda and the carbonate of soda contained in the spent lye. When
the liquid is evaporated the sulphate of soda separates in crystals, and is thus
recovered as a bye product. The sulphate of soda which has been introduced for
the purpose of separating the soap from the liquor is also separated, and if properly
purified can be again used for eliminating soap from soap-liquor. The liquid
remaining after the crystallisation is glycerine containing a slight proportion of
impurities, and can be further purified in the usual manner, as, for instance, by
distillation.
Having thus fully described the said Invention as communicated to me by my
foreign correspondent, and the manner of performing the same, I wish it understood
that I claim,-
First. In the manufacture of soap, the employment (for separating the soap
from the soap liquor) of sulphate of soda or other alkaline sulphate to facilitate
the recovery of pure glycerine from the spent lye, as above set forth.

page_text: Second. The employment of hydric sodic sulphate for neutralizing the lye
(produced in separating the soap from the soap liquor by sulphate of soda) for the
recovery of sulphate of soda as a bye product, as above set forth.
In witness whereof, I, the said Henry Harris Lake, have hereunto set my
hand and seal, this Eighth day of October, in the year of our Lord One
thousand eight hundred and eighty one.
HENRY H. LAKE. (L.S.)