Year: 1899

page_text: I, ADOLF SPITTELER, of Villa Bernhartzeder, Prien, in Bavaria, Germany, Chemist,
do hereby declare the nature of this invention to be as follows:-
The solutions hitherto obtained from the ordinary paranucleoproteids, such as the
usual commercial caseins, are all more or less opaque, and the manufacture of
transparent products from the paranucleoproteida has, therefore, been restricted to
the use of the purer and more expensive kinds, even when the cheapest caseins would
in all other respects have answered the purpose.
I have discovered, however, that the impure caseins can be decomposed by caustic
alkalies in such manner that the substances which cause the non-transparency are
rendered insoluble, while the casein or, more correctly, a derivate of the casein is
obtained in a solution as clear and transparent as water, from which the insoluble
particles can readily be separated by filtration, decantation, etc. My invention
relates to the application of this discovery.
In order to illustrate the peculiar action of orustic alkalies on the commercial
caseins I give in detail one of my experiments. To one part of cheap commercial
casein 4 parts of an aqueous solution containing 21 per cent (calculated on the
dry casein) of caustic soda were added and a homogeneous but opaque solution of a
greyish milky colour obtained thereby.
To this casein solution further quantities of Na₂O in the form of a 5 per cent.
solution of commercial caustic soda were added when the following changes
occurred:

page_text: Further additions of caustic soda produced no further change.
The above example shews that the action of caustic alkalies on the caseins is
by no means of a uniform nature but depends on the quantity of alkali used. Even
double and treble the quantity of alkali requued for dissolving the casein produced
no apparent change in the casein solution, which if anything became rather thinner
than it was at first. When, however, the addition of a 5 per cent. Bolution of alkali
was continued, a most remarkable thickening occurred, notwithstanding the pro-
gressive dilution, until at last the casein solution was altered in such manner that
the casein, or rather its derivative, formed a clear transparent liquid in which a
muddy constituent floated. When left undisturbed the latter gradually settled,
leaving the solution as clear as water.
Further experiments have shewn, that heat as well as prolonged action of the
alkalies favours this decomposition of the caseins, which may also be effected very
rapidly by employing at once a sufficient quantity of alkali,

page_text: In practice I find the following a very convenient way of carrying out my
invention. I mix the dry casein with 2 or 3 times its weight of water, and allow it
to stand until the casein has begun to swell. The finer the casein 18 ground the less
time is required for this. Then I add in one portion the necessary quantity of
caustic alkali, in the form of a 5 per cent. solution. For the particular casein with
which the above detailed experiment was carried out, I find from 10 to 11 per cent.
of Na,O a sufficient quantity. After the whole has been well stirred I allow it to
rest, when the reaction soon takes place. In a couple of hours I am able to draw off
by means of a siphon the solution of the casein derivate as clear as water, though I
prefer to let the solution stand over night, by which time the sediment has settled
down into an almost compact mass. After the clear liquid has been drawn off I
exhaust the sediment by the addition of water.
The solutions of caseins obtained by means other than the use of caustic alkalies,
and even milk itself, can likewise be decomposed in the manner described, and my
process is even applicable to caseins showing signs of putrefaction.
The colour of the clear liquid obtained depends on the quantity and nature of the
impurities contained in the casein employed, as well as on the temperature used.
Ordinarily it is colourless or greenish-yellow, or brownish-red. The action of caustic
potash on the caseins is similar to that of caustic soda.
The different caseins, as is well known, differ greatly in solubility; but when it is
desired to ascertain what is the least surplus of caustic alkali required to decompose n
particular kind of casein by my process, a simple experiment, such as that described
above by way of illustration will serve.
When the insoluble particles have been removed from the clear casein solution the
latter may be worked up by known means into solids which are perfectly
transparent.
Dated this 31st day of August 1899.
ABEL & IMRAY,
Agents for the Applicant.
Process for obtaining Clear Solutions from Impure
Paranucleoproteids.
I, ADOLF SPITTELER, of Villa Bernhartzeder, Prien, in Bavaria, Germany, 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:
Dried coagulated paranucleoproteids are used as a substitute for horn, amber and
the like. The commercial products hitherto obtained, however, have been opaque so
that for many purposes they could not rival transparent materials.
The reason for this 18 that commercial paranucleoproteids such as are cheap
enough for general use are impure and cannot be dissolved to a clear solution by any
means hitherto known, and such turbid solutions as are obtainable cannot be clarified,
so that they yield dried and coagulated products which are opaque.
By my invention commercial paranucleoproteids such as ordinary casein can be
dissolved to clear solutions, the dried and coagulated products from which are
transparent.
For this purpose I treat the impure casein with a comparatively strong solution of
caustic alkali, such as one containing 5 per cent. of alkali, care being taken that the
quantity of alkali used is fai in excess of that required to convert the casein into
casein-alkali.

page_text: By this means the impure casein is separated or, it may be, decomposed into a
part which forms a clear solution in the alkali and a part which remains undissolved
and is easily removed from the liquid by filtration or decantation.
The following example illustrates the process :-
Dry casein, preferably finely divided, is mixed with 3 or 4 times its weight of
water and left until it has begun to swell. Caustic alkali is then added to the extent
of about 10 per cent. (calculated as Na₂O) of the weight of the dry casein and in the
form of a solution of 5 per cent strength. The mixture is well stirred and left until
the jelly at first formed has separated into a clear solution and a sediment. This
occurs in about 2 hours when the strength and proportion of the alkali are those
named, but the time varies within wide limits accordingly as these conditions are
changed. When the amount of clear liquid no longer increases, the solution is
decanted or siphoned from the sediment.
The concentration of the alkali is an important condition for the success of my
invention but exact limits for this cannot be named owing to the fact that commercial
casein is of widely different kinds. The 5 per cent. strength works well with a
common kind of casein.
It is not necessary that the casein should be in the solid form. An impure solution
of casein, such as milk, is equally capable of treatment by my process.
I am aware that impure casein has been dissolved in alkalies to obtain solutions of
casein, but such solutions have always been turbid and the matter causing turbidity,
being virtually in solution, has been inseparable by practical means
The discovery which is the basis of my invention 18 that when impure casein is
subjected to energetic action of caustic alkali, a chemical change occurs which renders
separable by practical means the matter which causes the aforesaid turbidity.
Having now 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 :-
1. The herein described process or obtaining clear .solutions from impure
paranucleoproteids by adding to the paranucleoproteid or to an impure solution
thereof, such as milk, a solution of caustic alkalı of suitable concentration which
contams a proportion of alkalı much in excess of that required to forin paranucleo-
proteid-alkali, and removing the insoluble particles from the liquid thus formed.
2. Clear solutions from impure paranucleoproteids manufactured as above set
forth
Dated this 21st day of May 1900,
ABEL & IMRAY,
Agents for the Applicant.