IMPROVE- MENTS IN THE MANUFACTURE OF SOAP
Year: 1884

page_text: I, WILHELM RÖDIGER, Manufacturer, residing in Magdeburg, kingdom of Prussia,
German Empire, do hereby declare the nature of the said invention for "IMPROVE-
MENTS IN THE MANUFACTURE OF SOAP" to be as follows:-
- I
The present invention in the manufacture of soap has for its object to neutralize
the excess of alkaline principles contained therein, by means of carbonic acid, and
it consists in mixing with the soup a suitable quantity of bicarbonate of soda at
such temperaturo as will not decompose the same.
By means of the said bicarbonate, the caustic soda will be converted into sodium
monocarbonate, or, if required, the sodium monocarbonate into the sesquicarbonate
of soda.
Instead of bicarbonate of soda certain other bicarbonates may be used.
Soaps neutralized as described do not act destructively upon the skin and may,
with great advantage, be employed for treating fibres and fabrics.
Dated this fourteenth day of June 1884.
:
WILHELM RÖDIGER,
By his Agent, Carl Kilper.
<>

page_text: I, WILHELM RÖDIGER, Manufacturer, residing in Magdeburg, Prussia, German
Empire, do hereby declare the nature of my Invention for "IMPROVEMENTS IN
THE MANUFACTURE OF SOAP," and in what manner the same is to be performed,
to be particularly described and ascertained in and by the following statement :-
This invention relates to the manufacture of soap, and it has for its object to
neutralize the excess of alkaline principles contained in the soap by means of
carbonic acid.
All soaps as are at present made, contain more or less free caustic alkali. The
greatest quantity thereof is to be found in soaps which are not salted out. In
curd-soaps, in the manufacture whereof the salting-out process is employed, the
amount is indeed but small, and the best toilet-soaps only present traces thereof.;
but even in minute quantities the free alkali acts prejudicially on the skin.
In order to obviate this inconvenience I mix with the soap a suitable quantity
of bicarbonate of soda at a temperature at which the said salt is not yet decomposed.
Under these conditions the second molecule of carbonic acid contained in the
bicarbonate, will pass over to the free caustic alkali, so as to convert it into sodic
monocarbonate, whereby the soap is deprived of the greater part of its acrid
character.
Considering however that, when the quantity of alkaline, monocarbonate thus
produced in a soap is great, and when the hands are exposed to the action of such
soap for a length of time, it will also attack the skin, it may be desired to convert
the free alkali into sesquicarbonate of potass or soda. For this purpose it is but
-necessary-to-add-so-much-bicarbonate of soda in proportion to the caustic alkali
originally present, as that a salt of the desired constitution, and which may be
expressed by the formula
Na, CO, +2 Na H CO3 + 2 H₂ 0
will be formed. If, as is often the case, the soap originally contains free mono-
carbonate of an alkali in addition to the caustic alkali, and if both are to be
converted into sesquicarbonate, this of course affects only the quantity of bicarbonate
of soda to be added.
Soaps neutralized as described are of special value in the treatment of fibres and
fabrics.
The particular mode of carrying out the process is as follows.
If curd soap is to be treated, it is first rendered as neutral as possible in the
ordinary process of manufacture. After having thereupon been salted out and
finished, a quantity of sodic bicarbonate equal to 1 per cent of the weight of the
fat contained in the soap, is incorporated into the same. The bicarbonate is
dissolved in 10 parts of water and mixed with the soap at a temperature not
exceeding 95° C. A conversion of the free caustic soda into carbonate of soda
having thus been brought about, the farther treatment of the soap is as usual.
In the case of soaps which are not salted out, the titre of caustic soda and
carbonate of soda has first to be ascertained in a sample of the soap after it has

page_text: been submitted to the salting-out process. By calculation the quantity of
bicarbonate of soda is hereupon determined which is required either for converting
the free caustic soda into monocarbonate, or the caustic and the carbonate of soda.
present into sesquicarbonate. The sodic bicarbonate is dissolved in the least
possible quantity of water of about 80° C. and mixed with the soap while the
latter is at a temperature below 90°.C.
In the manufacture of cocoa soaps designed to be used as toilet soaps, the
amount of bicarbonate of soda, ascertained by calculation or known from experience,
may be mixed with the soap on the soap-crushing machine.
. Instead of bicarbonate of soda other alkalic bicarbonates may be used.
Having thus particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is t
In the manufacture of soap the process of converting the free caustic alkali
contained in the soap, into monocarbonate or sesquicarbonate, or the free, alkalic
monocarbonate, originally present, into sesquicarbonate, by means of a bicarbonate
of an alkali added to the soap while being at a temperature at which the bicarbonic
salt does not yet decompose; substantially as and for the purpose described.
13.
•
1
T