Improvements in Clarifying or Removing Impurities and other Substances from Glue.
Year: 1894

page_text: Date of Application, 10th July, 1894
Complete Specification Left, 22nd Aug., 1894-Accepted, 22nd Sept. 1894
PROVISIONAL SPECIFICATION.
Improvements in Clarifying or Removing Impurities and other
Substances from Glue.
I, PETER COOPER HEWITT, of 11, Lexington Avenue, New York City,
United States of America, Manufacturer, do hereby declare the nature of this
invention to be as follows:-
The object of my invention is to provide a simple, inexpensive, and effective
method for removing impurities from glue, which will permit of easily removing
the purifying agent, together with the impurities, from the glue, and which will
remove odor and color, and will impart to the glue qualities hitherto attained with
difficulty.
In carrying out my invention I prefer to use casein derived from skimmed milk
as it comes from dairies. In the manufacture of butter, after the fatty bodies are
removed from the milk, the casein in the skimmed milk makes a cheese of inferior
quality. This cheese or casein I prefer to use, but it is not essential that it should
be free from oil. The casein is separated from the milk by heating the milk, then
touching it with rennet. The milk thus coagulated is allowed to stand until the
whey is separated, when the whey is poured off. The casein, after washing, is
dissolved in water rendered alkaline preferably by the addition of lime. I may
require lime in the proportion of about 10% of the dry weight of the casein. This
proportion varies with the age of the casein and the manner of manufacture, but
it is usually less.
This solution of casein, either without modification, or modified when necessary,
as explained below, is added to the glue solution and unites with the impurities
therein, separating them from the glue and rendering the glue clear by removing
from the glue solution, grease and other impurities and also removing color and
odor, at the same time imparting to the glue, among other desirable qualities, great
limpidity and freedom from foaming. The separation of the casein and impurities
from the glue may be hastened by heat, also by a change in acidity or by the use
of rennet.
The modifications of the casein which may in some cases be advisable are as
follows:-For the treatment of some glue solutions it is advisable to add to the casein
solution, albumen (preferably albumen derived from blood) in proportions
The necessity
varying from five to fifty per cent. of the dry weight of the casein.
for this addition of albumen arises from a deficiency of albumen substance in the
casein or glue solution. The quantity necessary can be most conveniently
determined for each quality of casein and glue by a preliminary test, or the
original casein solution inay be added to the glue solution first, and if the desired
effect is not secured the diluted albumen may then be introduced into the mixture
by successive additions until the desired result is secured. This amount once
determined in either way will serve to guide all operations where the quality of
casein and glue remains the same. For some uses it is desirable that the casein
should not be alkaline but neutral or even acid. In such cases the alkaline casein
solution may be neutralized and acidulated with a suitable acid, preferably
phosphoric acid.
If casein is first brought into acid solution, the coagulation can be effected by a
change in the acidity of the solution on the addition of an excess of acid, or
preferably by bringing it to a neutral state or an alkaline state.

page_text: The clarifying agent is evaporated and put in packages for preservation and for
storage 'for future use. For this purpose either the original casein solution or a
casein solution to which albumen has been added, may be evaporated. When the
clarifying agent thus prepared comes to be used, a suitable quantity of water is
added to reduce it to the required strength.
In the manufacture of glue when the stock is rendered by heating, the gelatine
going into solution carries with it other constituents of the stock. These are now
removed with great difficulty, by large filters and the use of clarifying agents, such
albumen and alum. These all have decided objections, well known to glue makers,
albumen being expensive and leaving the glue foamy, besides causing the glue to
filter very slowly through the coagulum, and alum being uncertain, besides leaving
acid or its salts in the glue, injuring the quality, and the agent and the impurities
are separated with very great difficulty, after the operation is completed, by
filtration, as in this case, also, the precipitate clogs the filter.
To apply the clarifying agent to the purification of glue, I mix it with the glue
in solution as it comes from the boiler, in about the proportion of one pound of the
agent (dry weight) to one thousand pounds of the glue solution, the dry glue being
about 10% of the solution. I thoroughly mix the agent and the gluc, and the agent
uniting with the impurities coagulates, the process of coagulation being hastened
and aided by heat, by change of acidity, or by the use of rennet, or as already
stated. The coagulum separates when formed. The applied heat hardens the
precipitate and coagulum. To remove this coagulum I use any of the well known
means, such as settling, or filtration, or centrifugal force, as there is no difficulty in
removing it. Should the combination of the phosphoric acid with the lime produce
insoluble lime phosphate this is removed in the coagulum. In the case of a filter
being used, the precipitate does not clog the filter, as it is of such a nature that it
keeps itself separated, allowing the liquid to pass freely through it.
In cases
where alumina is added to the glue, or formed in the glue from the sulphate of
alumina, my improved agent and process will readily remove it, carrying it out in
the coagulum with the other impurities.
Casein yields a precipitate of firm structure which offers but little impediment to
the filtration of the glue solution through it, and should coagulated albumen or
alumina be present during the coagulation the resulting precipitate becomes
harder, offering less resistance to filtration, than the albumen or alumina, and
resembles the casein precipitate.
After clarifying the glue in the manner described, it may be treated by the
usual methods. If desirable it may be bleached either before or after clarification.
This agent is particularly adapted for removing color from glue, in connection with
other bleaching agents, such as sulphurous acid, or hydro-sulphurous acid formed by
the action on metallic zinc of sulphurous acid added to the liquor.
The bye-product of the process, which consists of the coagulum and the
impurities of the glue, is used as a fertilizer. This bye-product may be disposed
of in the state in which it is removed from the glue, or it may be dried to render it
more fixed and portable.
"
By the word "hardener as used herein, I mean an agent which renders the
precipitate more easy of removal from the liquid, by imparting to the precipitate a
firmer nature. By the term "alumina " as herein used I mean precipitated
gelatinous alumina. By the term "casein" as used herein I mean any form of
casein, whether of animal or vegetable origin.
Deted this 10th dove of T.1. 1904

page_text: Improvements in Clarifying or Removing Impurities and other
Substances from Glue.
1 PETER COOPER HEWITT, of 11 Lexington Avenue, New York City, in the
County and State of New York, United States of America, Manufacturer 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 :-
The object of my invention is to provide a simple, inexpensive and effective
method for removing impurities from glue, which will permit of easily removing
the purifying agent together with the impurities from the glue, and which will
remove. odour and color, and will impart to the glue qualities heretofore attained
with difficulty.
In carrying out my invention, I prefer to use casein derived from skimmed milk
as it comes from dairies. In the manufacture of butter, after the fatty bodies are
removed from the milk, the casein in the skimmed milk makes a cheese of inferior
quality. This cheese or casein I prefer to use, but it is not essential that it should
be free from oil. The casein is separated from the milk by heating the milk, then
touching it with rennet. The milk thus coagulated is allowed to stand until the
whey is separated, when the whey is poured off. The casein after washing, is
dissolved in water rendered alkaline preferably by the addition of lime. I may
require lime in the proportion of about 10 per cent. of the dry weight of the casein.
This proportion varies with the age of the casein and the manner of manufacture,
but it is usually less.
This solution of casein, either without modification, or modified when necessary
as explained below, is added to the glue solution and unites with the impurities
therein, separating them from the glue and rendering the glue clear, by removing
from the glue solution, grease and other impurities, and also removing color and
odor, at the same time imparting to the glue, among other desirable qualities,
great limpidity and freedom from foaming. The separation of the casein and
impurities from the glue may be hastened by heat, also by a change in acidity or
by the use of rennet.
The modifications of the casein which may in some cases be advisable, are as
follows. For the treatment of some glue solutions it is advisable to add to the
casein solution, albumen (preferably albumen derived from blood) in proportions
varying from five to fifty per cent., of the dry weight of the casein. The necessity
for this addition of albumen arises from a deficiency of albumen substance in
the casein or glue solution. The quantity necessary can be most conveniently
determined for each quality of casein and glue by a preliminary test, or the
original casein solution may be added to the glue solution first, and if the desired
effect is not secured, the diluted albumen may then be introduced into the mixture
by successive additions, until the desired result is secured. This amount once
determined in either way will serve to guide all operations where the quality of
casein and glue remains the same. For some uses it is desirable that the casein
should not be alkaline, but neutral or even acid. In such cases the alkaline casein
solution may be neutralized and acidulated with a suitable acid, preferably
phosphoric acid.
If casein is first brought into acid solution, the coagulation can be effected by a
change in the acidity of the solution, on the addition of an excess of acid, or
preferably by bringing it to a neutral state or an alkaline state.
The clarifying agent is evaporated and put in packages for preservation and for
storage for future use. For this purpose, either the original casein solution, or a

page_text: casein solution to which albumen has been added may be evaporated. When the
clarifying agent thus prepared comes to be used, a suitable quantity of water is
added to reduce it to the required strength.
In the manufacture of glue when the stock is rendered by heating, the gelatine
going into solution carries with it other constituents of the stock. These are now
removed with great difficulty by large filters and the use of clarifying agents such
as albumen and alum. These all have decided objections well known to glue
makers, albumen being expensive and leaving the glue foamy, besides causing the
glue to filter very slowly through the coagulum, and alum being uncertain, besides
leaving acid or its salts in the glue, injuring the quality, and the agent and the
impurities are separated with very great difficulty after the operation is completed,
by filtration, as in this case also the precipitate clogs the filter.
To apply the clarifying agent to the purification of glue, I mix it with the glue
in solution as it comes from the boiler, in about the proportion of one pound of the
agent (dry weight) to one thousand pounds of the glue solution, the dry glue being
about 10 per cent. of the solution. I thoroughly mix the agent and the glue, and
the agent uniting with the impurities coagulates, the process of coagulation being
hastened and aided by heat, by change of acidity, or by the use of rennet, or as
already stated. The coagulum separates when formed. The applied heat hardens
the precipitate and coagulum. To remove this coagulum, I use any of the well
known means, such as settling, or filtration, or centrifugal force, as there is no
difficulty in removing it. Should the combination of the phosphoric acid with the
lime produce insoluble lime phosphate, this is removed in the coagulum. In the
case of a filter being used, the precipitate does not clog the filter, as it is of such a
nature that it keeps itself separated, allowing the liquid to pass freely through
In cases where alumina is added to the glue, or formed in the glue from the
sulphate of alumina, my improved agent and process will readily remove it, carrying
it out in the coagulum with the other impurities.
it.
Casein yields a precipitate of firm structure which offers but little impediment. to
the filtration of the glue solution through it, and should coagulated albumen or
alumina be present during the coagulation, the resulting precipitate becomes harder,
offering less resistance to filtration than the albumen or alunina, and resembles the
casein precipitate.
After clarifying the glue in the manner described, it may be treated by the
usual methods. If desirable, it may be bleached either before or after clarification.
This agent is particularly adapted for removing color from glue, in connection with
other bleaching agents, such as sulphurous acid, or hydro-sulphurous acid formed
by the action on metallic zine of sulphurous acid added to the liquor.
The bye-product of the process, which consists of the coagulum and the impurities
of the glue, is used as a fertilizer. This bye-product may be disposed of in the
state in which it is removed from the glue, or it may be dried, to render it more
fixed and portable.
By the word "hardener" as used herein, I mean an agent which renders the
precipitate more easy of removal from the liquid, by imparting to the precipitate a
firmer nature. By the term " alumina as herein used, I mean precipitated
gelatinous alumina.
"
دو
By the term "casein as used herein, I mean any form of casein, whether of
animal or vegetable origin.
Having now particularly described and 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,
1. The improved method of clarifying glue, which consists in adding to and
thoroughly mixing casein in solution with the glue solution, causing the casein to
unite with albuminous substances and other impurities in the glue and become
insoluble, thereby separating such impurities from the glue, and finally removing
the resulting coagulum from the glue solution.

page_text: 2. The method of clarifying glue, which consists in adding to and mixing with
the glue solution, casein and albumen in solution heating the mixture, causing the
solution of casein and albumen to unite with the impurities in the glue solution
thus forming an insoluble compound, and thereby separating the mixture of casein
and albumen, together with the impurities from the glue, and finally removing the
same from the glue solution, as herein specified.
3. The method of hardening albumen coagulum, which consists in adding casein
to the solution containing albumen, then coagulating the mixture, as specified.
4. The method of removing alumina from glue in solution, which consists in
adding to the glue solution containing the alumina, a solution of casein coagulable
in the glue solution, then coagulating the same, forming a coagulum of casein and
alumina and separating the coagulum from the liquid, as specified.
5. The method of preparing a casein albumen clarifying agent, which consists in
dissolving cheese in an alkaline water, then adding blood albumen in solution, as
specified.
Dated this 20th day of August 1894
A. M. & WM. CLARK,
53, Chancery Lane, London, Chartered Patent Agents.