Improvements in the Manufacture of Soap and Glycerine.
Year: 1894

page_text: Date of Application, 20th Sept., 1894
Complete Specification Left, 20th June, 1895-Accepted, 20th July, 1895
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Soap and Glycerine.
JAMES KAY HILL Fullarton Cottage, Irvine, Ayrshire Manufacturing Chemist
do hereby declare the nature of this invention to be as follows:—
A process for cleansing soap in course of manufacture, by adding excess [of
alkali instead of salt, and afterwards removing the residual alkali from the separated
lyes, at the same time obtaining spent lyes containing glycerine with a much
smaller proportion of salts than is possible by the ordinary methods hitherto
employed.
I have found that the glycerine and impurities commonly found in soap during
the process of manufacture can be easily and advantageously removed by the
addition of an excess of caustic alkali or a mixture of caustic and carbonated alkali.
This excess of alkali separates from the soap on standing, and is collected and used
for the saponification of more fat or rosin, any carbonate of soda present being
converted into caustic soda by means of lime if necessary and the operation of
saponification being repeated as often as required to free the spent lyes from the
excess of alkali which has been employed in the first cleansing of the soap.
The residual spent lyes thus obtained contain practically the whole of the
available glycerine together with the impurities separated from the soap, but no
salt except the small quantity derived from the alkali used. Therefore the
subsequent operations of concentrating and refining the glycerine are much easier
and less costly than by the old method.
When using caustic soda of commerce I prefer the excess of alkali for cleansing
the soap to be caustic alkali entirely, but when soda ash or ammonia soda has to be
causticised the lyes may be causticised at a high strength to save the cost of
concentration by evaporation, and the unconverted carbonate of soda remaining in
the lyes can take the place of a portion of the excess of caustic soda otherwise
required to cleanse the soap as previously described above.
Dated this Nineteenth day of September 1894.
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Soap and Glycerine.
JAMES KAY HILL, Fullarton Cottage Irvine, Ayrshire, Manufacturing Chemist
do hereby declare the nature of this invention and in what manner the same is
to be performed, to be particularly described and ascertained in and by the
following statement :-
A process for cleansing soap in course of manufacture by adding excess of
alkali instead of common salt and afterwards removing the residual alkali from
the separated leys at the same time obtaining spent leys containing glycerine
with a much smaller proportion of salt than is possible by the ordinary methods
hitherto employed.

page_text: I have found that the glycerine and impurities commonly found in soap during
the process of manufacture, for the removal of which common salt has hitherto
being used can be easily and advantageously separated from the soap by the
addition of an excess of caustic alkali or a mixture of caustic and carbonated
alkali. This excess separates on standing and is collected and used to saponify
more fat or rosin, any carbonated alkali when present in quantity being causticised
by the use of lime if necessary and the operation of saponification being repeated
until the excess of alkali in the ley is spent.
The residual leys thus obtained contain all the available glycerine together with
the impurities separated from the soap but no salt except the small quantity
derived from the alkali used; therefore the subsequent operations of concentrating
and refining the glycerine are much easier and less costly than the old method.
When using caustic soda of commerce I prefer the excess of alkali used for
cleansing the soap to consist of caustic soda entirely but when soda ash or
ammonia soda has to be causticised for this purpose, the liquors may be causticised
at high strength to save the cost of evaporation, and the unconverted carbonate
of soda can be made to take the place of a portion of the excess of caustic soda
otherwise required to cleanse the soap as previously described above.
Instead of using an excess of caustic ley to cleanse the soap, I may use solid
caustic soda which produces practically the same result by dissolving in the soap
pan and forming an excess of ley which separates as already described.
Having now particularly described & ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is,
1st. The use of an excess of caustic alkaline ley or a mixture of caustic and
carbonated alkaline ley instead of common salt for the purpose described.
2nd. The alternative use of solid caustic soda as described.
3rd. The subsequent operations of removing the excess of alkali substantially as
described.
4th. The easier and cheaper concentration of the leys for the obtainment of
glycerine by reason of the almost total absence of common salt, the saving in
time, labour, and fuel, and the reduction of wear and tear in the working plant.
Dated this 19th day of June 1895.
JAS. KAY HILL.