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ITS PREPARATION AND
TECHNICAL UTILISATION

BY

ROBERT SCHERER

TRANSLATED FROM THE GERMAN

THIRD ENGLISH EDITION, REVISED AND ENLARGED

By H. B. STOCKS, F.LC, FCS.

WITH SEVENTEEN ILLUSTRATIONS

LONDON
SCOTT, GREENWOOD & SON

8 BROADWAY, LUDGATE, E.C. 4
1628 ©

[The sole right of translation into English rests with Scott, Greenwood & Son]

a
_ BIBLIOGRAPHICAL NOTE
First German Edition ; ah ae : ? : 1905
First English Edition .. : 1906
Second English Edition, pevised aul gelaread. . IQiII

Third English Edition, revised and enlarged September, 1921

Main Lib. Sa ai Bk
AGRIC. DEPT. Nn v me ¥ Bs te D.. er ey,

PREFACE TO THIRD EDITION.

For many years the sole use found for milk curd was
in the manufacture of cheese to be used as a food-
stuff. Skimmed or separated milk, produced in large
quantities as a by-product in butter-making, was fed
to pigs or even run into a stream. It is only through
the scientific researches of the past few decades that
the true value of albuminoid substances has been
realised and that the manufacture of casein from
skim milk has become a practicable proposition. In-
cidentally to this, the preparation of milk sugar has
become a possibility, and the easy digestibility of this
product has resulted in its being used in infants’
foods and similar preparations.

It is easy to understand that our knowledge of
casein is somewhat imperfect, especially as regards
its manifold uses, but as time goes on it will become
more and more appreciated in industrial applications
since it has valuable properties which are not easily
found in any other product. Communications on the

subject in the technical press are rare, consequently
iii

456250

iv PREFACE.

it appeared desirable to the reviser to prepare a work
dealing with this material. ,

The first part of this book treats upon the pre-
_ paration of curd from milk, by decomposition of the
suspended casein compound with acids or with rennet, _
and the purification and drying of the precipitated
casein. Following this, the composition, properties,
and reactions of casein are touched upon; then
follows a description of the use of casein in the
manufacture of paints, distempers, putties, plastic
masses, artificial ivory, and other materials; the
modes of applying these and their special features.
The use of casein as a dressing for paper and cloth
and its employment for waterproofing and other pur-
poses is also described, and finally there are chapters
on the use of casein in nutrient preparations, and the
compounds of casein employed for medicinal purposes.

In compiling this work the reviser has endeavoured
to bring together as much useful information as pos-
sible, and acknowledges his indebtedness to, many
investigators who are mentioned in the text and
- footnotes.

THE REVISER.

Lonpon, August, 1921.

CONTENTS.

° PAGES
PREFACE ° . . ° . ° ‘ ‘ ‘ : ; be FL

CHAPTER I. |
THEPRODUCT IN ost, a en ee ee Ae

CHAPTER II.
CASEIN: ITS: ORIGIN, PREPARATION AND PROPERTIES.

The preparation of casein; Heating pans for the preparation of casein;
Steam generator ; Washing the curd; Drying cylinders; Vacuum eva-
porators; Purifying the curd; Filter press; Vegetable casein . . 38-29

CHAPTER III.
VARIOUS METHODS OF PREPARING CASEIN.

Hatmaker’s method; Hall’s method; Spitteler’s method; Process of
Mierisch and Eberhardt; Riegel’s method; Szekely’s patent; Bel-
lamy’s method; Hoppe-Seyler method; Besana’s method; Just’s
method; Ricard and Riche’s patent; Dunham’s patent; Baechler’s
patent , tee ‘ ‘ ‘ ‘ i ‘ e . . 30-40

CHAPTER IV.
COMPOSITION AND PROPERTIES OF CASEIN.

Analyses of caseins ; Properties of casein ; Reaction with various reagents ;
Estimation of casein; Analyses of industrial caseins . ‘ i - 41-57
v

vi CONTENTS.

CHAPTER V.

CASEIN PAINTS.
PAGES

Sifting machine; Marble lime colour for outside work; Casein enamel
paint; Cone paint mill; Cold-water paint in powder form; Casein-
lime colours; Pure casein paints for walls, etc. ;. Water-colour paints ;
Casein-silicate paints; Milk paints; Trojel’s boiled oil substitute;
Casein paints ; Water-white casein varnish ; Formolactin ; Waterproof
paint for playing cards; Paint for marking bags, iron barrels, cases,
etc.; Casein-cement paint . ‘ ‘ : : : . * . 58-86

CHAPTER VI.
THE TECHNICS OF CASEIN PAINTING.

Preparation of the ground ; Preparation of the binding medium; Prepara-
tion and application of the casein paint . : , . : 87-103

CHAPTER VII.
CASEIN ADHESIVES AND PUTTIES.

Casein glue; Bolder’s liquid casein glue; Crosspietsch’s adhesive; Jero-
-min’s casein adhesive; Hall’s casein glue; Waterproof glue; Liquid
casein glue; Powdered casein glue; Casein and borax glue; Casein
for mending glass, china, etc. ; Solid casein adhesive ; Casein solution ;
Joining casein plates ; Soluble casein compound; Renken’s method of
using glue; Glue powder; Lehner’s casein putties; Casein biad for
meerschaum ; Casein-soda cement; Washable cement for deal boards ;
Wenk’s casein cement; Casein and lime cement; “Pitch barm” ;
Casein stopping ; Casein cement for stone; Insoluble casein . 104-120

CHAPTER VIII.
THE PREPARATION OF PLASTIC MASSES FROM CASEIN.

Imitation ivory; Lilienthal’s plastic mass; Jung, Brecher & Kittel’s in-
sulating preparation; Anti-radiation and anti-corrosive composition ;
Dickmann’s covering for floors and walls ; Imitation linoleum ; Imita-
tion leather; Imitation bone; Artificial horn, etc.;. Plastic mass of
keratin and casein; Insulating mass; Plastic casein masses; Horny
casein mass; Casein-cellulose compositions ; Celluloid substitutes ;
Galalith ; Insoluble preparation of casein; The condensation of casein,
phenol, and formaldehyde . j ¢ : ; ‘ ° - 121-146

CONTENTS.

CHAPTER IX.

Vii

USES OF CASEIN IN THE TEXTILE INDUSTRY FOR FINISHING

PURPOSES, COLOUR PRINTING, ETC.

Caseogum; ‘‘Glutin”’; Casein dressing for linen and cotton fabrics;

Argentine ; Printing colour with metallic lustre ; Process for softening,
sizing, and loading textile fibres, etc.; Fixing casein and other albu-
minoids on the fibre; Fixing insoluble colouring matters; Water-
proofing and softening dressing ; Casein for mercerised crépe; Fixing
zine white on cotton with formaldehyde; Casein-magnesia; Casein
medium for calico printing; Chevallot’s waterproofing process ; Load-

PAGES

ing silk; Threads, blocks, plates, etc., of casein; Sizing material 147-157

CHAPTER X.

CASEIN FOODSTUFFS.

Lactarine; Galactogen; Gutimann’s nutrient milk flour; Sanatogen ;

Eulactol; Dr. Riegel’s milk albumen; Plasmon; Nutrium; Casein
food ; Casein as a substitute for egg albumen; Synthetic milk; Milk
food; Emulsifiable casein; Casein phosphate for baking; Bernstein’s
baking preparation; Higgins’s casein food; Preparing soluble casein
compounds with citrates; Sell’s curd ‘“zwieback” rolls; Food

powder. : ‘ ; : ° ° “ ; : . 158-166

CHAPTER XI.
SUNDRY APPLICATIONS OF CASEIN.

of casein in the paper industry ; Metachromotype paper; Sizing paper
with casein; Waterproof paper; Casein solution for coating paper ;
Horn*s clear solution of casein; Facing for paper; Waterproof and
fireproof asbestos paper and board; Paper flasks, etc., for oils and
fats; Washable drawing and writing paper; Paint remover; Beuse’s
shoe polish ; Casein shoe cream ; Casein photographic plates ; Wood-
cement roofing pulp; Cask glaze of casein and formaldehyde; The
preparation of artists’ canvas; Solidifying mineral oil; Use of casein
in photography ; Casein ointment ; Clarifying glue with casein ; Casein
in soapmaking; Eberhardt and Mierisch’s soluble casein; Water-

PROC CORMI e ic hO es) tee epee Reis ROO Eee

Vill , CONTENTS.
CHAPTER XII.

CASEIN COMPOUNDS.
PAGES
With iodine; Albumose and peptone from casein; Casein phosphate ;
With salicylates ; With alkaloids ; With organic acids; With lithium
salts, mercury, silver and iron compounds; With arsenic; Alkali
salts; Insoluble casein compounds; With acrolein; Pure casein ;
Pure paracasein; Ammonium compound; Hydrochloric acid’ com-
pound ; With formaldehyde ; With glycerophosphates ot es B6-201

INDEX * v . a : > ‘ ‘ , $ ; . 203-213

4

CHAPTER I.

INTRODUCTION.

ALTHOUGH casein, in the form of cheese, has from time
immemorial played an important part in the dietary of the
human race, and has been produced in very large quantities,
the technical utilisation of this product was almost entirely
neglected. The property which it has of dissolving in
alkaline liquids and forming, in this condition, a good
mucilage, has long been known; but this was all, and it
is only within a comparatively short space of time that any
extensive technical application of casein has been made.

Casein is now used as a paint, as a dressing for textiles, a
cement and mucilage, in the production of plastic masses,
for sizing paper, and various other purposes. Since close
attention has been bestowed on the action of formaldehyde
on casein, a whole series of new uses has been discovered for
the article, which is undoubtedly destined to play a very
important part in technology. Furthermore, the original
application of it as a foodstuff has not been lost sight of ; its
high nutritive value and its easy assimilability having led
to the preparation of a number of artificial foods which are
now extensively consumed. In cases where, owing to lack
of means of communication, milk cannot be sent to large
centres of population for consumption, it is now converted
into butter and casein, the latter being disposed of for
technical purposes.

In America considerable importance is attached to the

manufacture and treatment of casein. It already forms
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an important article of commerce there, especially in paper-
making, the manufacture of sized papers, and in painting
and calcomining, and so forth; but for these purposes pro-
duction on a large scale is indispensable. Owing to the
highly diversified uses of casein, those of a technical
character being naturally the first to be considered, it
seemed desirable to divide the present work into a series
of chapters, each complete in itself, as follows :—

The preparation and properties of casein ; followed by its
application :—

Asa painting material ;

As a mucilage and cement ;

In the preparation of plastic masses, to be used as sub-
stitutes for horn, ivory, celluloid, etc., with special
attention to ‘‘ Galalith ”’ ; 7

As a dressing and colour-fixing medium in the textile
industry ;

As a foodstuff; and for other various purposes which do
not come within the other groups.

Finally, a summary will be given of most of the known
compounds of casein with chemical elements, their salts, etc.,
and organic compounds which may become useful in course
of time. The scattered literature of the subject has been

consulted, and quotations have been made where they served
a useful purpose.

CHAPTER II.
CASEIN: ITS ORIGIN, PREPARATION AND PROPERTIES.

THE milk of mammiferous animals, from which casein is
derived, is a normal secretion of the healthy lacteal glands of
the female animal. After the flow of colostrum (the first
milk secretion after parturition) has ceased, normal milk is
produced for a certain time, which is known as the period of
lactation. Speaking generally, varying with the species, the
milk of mammals is an opaque, whitish, or faintly yellow
liquid, exhibiting a peculiar specific taste and smell. It
consists of water, fat, casein, albumin, milk sugar and
inorganic constituents, the most important being the fat and
casein. Cows’ milk is by far the most important, the solid
matter consisting, according to Kirchner, of :—

Average. Min. Max.
Fat . ; : . 3°4 per cent, 0°8 to 80 percent.
Casein . ‘ es ie be 20. 4:48 3
Albumin . ; 1 6 Ne Ore. = O8 sa
Lactoprotein . a. OI Me O08 >, O85.- 4;
Milk sugar ; . 4% . 0°73": ,; 6°0 i
Ash ; ‘ ar | ¥ 06 ,, 09 me

The average composition of milk, according to Keenig,

1s :—
Specific gravity . ' : : ; . 1:0316
Water ‘ Wt thr P ‘ : . 87-27
Casein é : ; ; : ‘ « | ¥02
Albumin: ..°-:. : ; : - 058
Fat. : * ; : : ; . 8°64
Milk sugar . ‘ ; : Soc ioe
Ash. 4 , r ; i ; ais) QFE

(3)

ee | CASEIN.

Milk must be regarded as an emulsion, «¢., a hetero-
geneous liquid containing substances in suspension in a very
finely divided state, and we must assume that the fat globules
—the future butter—for instance, are surrounded by colloidal
envelopes. The liquid fat globules attract substances dis-
solved in the milk and condense the same around themselves,
so that we may safely assume that every fat globule is
surrounded by an envelope richer in dissolved substances
than the milk itself.

The Preparation of Casein.—When fresh, whole milk is
left at rest, or is subjected to very rapid rotary motion by
means of special appliances (centrifugal machines), the cream,
or portion richest in fat, rises to the surface, and if this be
skimmed off, skim milk is left. This latter forms the raw
material for the preparation of the second chief product of
milk, namely, the casein, which is’ present to the extent of
2 to 4'5 per cent., the average being 3°2 per cent. Casein is
not dissolved in the milk, but is suspended in a state of
distension, which can be proved by a simple experiment. If
milk be filtered through a porous earthenware plate, the
filtrate obtained consists merely of a solution of milk sugar
and saline constituents, the fat and casein, neither of which
is in solution, being left behind on the surface of the filter.

According to A. W. Bosworth and L. L. Van Slyke,’ the
residue left on passing milk through a Chamberland filter
was composed of calcium caseinate (Casein — Ca,) and
neutral dicalecium phosphate.

The behaviour of milk under various conditions is deter-
mined by this peculiar condition of the casein present. This
is the cause of certain physical properties of the milk, notably
the viscosity, which in turn influences the rate at which the
cream rises. The condition of the casein is not altered by
warming or boiling the milk ; but, on the other hand, it is

1 Jour. Bio, Chem.,’’ 1914, 19, 67-71.

CASEIN: ITS ORIGIN, PREPARATION AND PROPERTIES. 5

precipitated by dilute acids or rennet. The precipitated
casein is insoluble in water or dilute acids, and forms when
dried a crumbling, horny mass; but it is dissolved by alkalis
and concentrated acids. This behaviour of casein leads to
the conclusion that it does not exist in a pure state in milk; .
and, in fact, experiments have shown that it occurs therein
as a compound of lime containing 1°55 per cent. of CaO.
According to H. Droop Richmond, it is held in solution by
solium calcium phosphate. This circumstance explains its
behaviour towards dilute acids, 2.¢., its precipitation thereby,
the lime being extracted by the reagent and the casein left in
the solid form. Only a very small quantity of acid is needed
to effect this precipitation, 1 per cent. of lactic acid (from the
milk sugar) being sufficient to curdle the milk. In addi-
tion to casein, small quantities of albumin (0°6 per cent.),
lactoglobulin (traces), and lactoprotein are also present.
Hammersten states that there are three proteids in milk:
viz., casein, lactalbumin, and globulin, the former constituting
by far the larger proportion, amounting to about 80 per cent.
of the total. Owing to the force of circumstances, it is
seldom that casein products are prepared in the same place
as the crude casein is produced, the raw material being
generally obtained from dairies at a distance. For this
reason the description of the mode of preparing the crude
casein will be confined to the indispensable minimum.
Casein belongs to the group of animal albumins, com-
pounds of carbon, hydrogen, oxygen, nitrogen, and sulphur,
of which it may be said that comparatively little is known
of their exact constitution. ‘There are a number of these
substances known, differing from one another in their general
- properties. White of egg, blood albumin, and the casein
of mtlk, are examples; they have been the object of much
investigation at the hands of chemists, although very little
that is absolutely certain is known of them. In milk there

6 CASEIN.

exists, first, the fat which forms the basis of butter, then a
small quantity of sugar, and, in pseudo-solution, a nitrogenous
substance to which the name of casein is given. This pro-
duct may be precipitated out by the addition of a little acid
or by some metallic salt. When the precipitation is brought
about by the action of rennet on ordinary milk, all the casein
and fat are thrown out together, and the product pressed
forms the foodstuff, cheese. If, however, by the use of
separating machines the fat is first extracted as butter, then
on precipitation almost pure casein is obtained. It may be
noted here that the action of rennet is somewhat different to
that of acids, inasmuch as the former does not completely
throw down the casein, but leaves a certain proportion in
solution. It is believed by Halliburton that the casein does
not exist as such in the milk, but in the form of caseinogen.
When the ferment rennet is added it is split up into casein
and albumin; the former is thrown out as curds, the latter
remaining in solution. When acid is used, all the caseinogen
is converted into casein. The casein of commerce is obtained
from separated milk by precipitation with acid. At present
the great bulk comes from America, but some also from
Scandinavian countries. Little, if any, is made in this
country, because there is such a great demand for milk as a
food product, that there is little, if any, surplus left for the
manufacture of casein. While but little is known as to the
caseins from various animal milks, yet it is quite evident they
vary a little in some respects, although closely resembling
one another in many properties (see p. 43). Casein comes
into commerce as a yellowish-tinted, crumbly powder. It is
here that it has an advantage over glue, for the latter is not
obtainable in the form of a powder, and it is this difference
that enables dry powder distempers to be made and sold,-when
casein forms a binder. It is nearly insoluble in water but dis-
solves more readily than glue when properly treated ; alkalies

CASEIN: ITS ORIGIN, PREPARATION AND PROPERTIES. t

like soda, caustic soda, and lime, facilitate the solution, and
so dry slaked lime is one of the constituents of distemper.
On exposure to the air this lime is converted into carbonate,
the casein separating out and exerting a binding effect on
the pigment. Casein alone does not produce a reliable
washable distemper, although it helps considerably; the
presence of a little linseed oil is needed, which, when used
in the paint, oxidises and binds the pigment firmly. In a
dry condition casein will keep for a long time, but when
moist, like all other nitrogenous bodies, it undergoes putrefac-
tive decomposition, to prevent which there may be added
preservatives such as carbolic acid, thymol, salicylic acid,
zinc sulphate, or zinc chloride.

Casein is recovered from skim milk (whole milk contain-
ing too much valuable butter to be used for the purpose) by
throwing down the suspended substance with suitable re-
agents. These may be of two kinds. On the one hand, as .
already mentioned, acids, including the lactic acid formed as
a fermentation product of the milk sugar, will curdle the
milk and thus precipitate the casein; and, on the other, the
same result can be brought about by the use of certain
ferments, of which the rennet ferment, or lab, is the chief.
At one time the product was regarded as the same in both
cases, but careful experiment has shown that a considerable
difference exists between them, pure casein being obtained
when acids are used, whereas rennet furnishes the so-called
paracasein, a fission product of the ordinary substance.
Hence it is necessary to regard the two reagents as distinct
in their action, this being a point of special importance when
cheese-making is in question. ,

In order to secure the correct precipitation of the casein
the milk must be kept at a certain temperature, not exceeding
140° F. nor lower than 68° F., since beyond these limits the
action of the rennet is weakened and very imperfect. The

8 CASHIN.

milk may be warmed either by direct fire heat or by steam,
a jacketed pan being used in the latter case.

Rennet is an-enzyme which is generated by special glands
in the stomachs of many animals, and is especially plentiful
in the case of young animals. The rennet used in cheese-
making is obtained from the stomach of the calf which is
dried at the ordinary temperature, comminuted, and then
extracted with a 5 per cent. solution of common salt, which
dissolves the enzyme.

A small quantity of this fluid rennet, added to a large
volume of milk, causes it to coagulate, forming a thick curd
and a thin fluid or whey. According to Sédldner, 1 part of
rennet is capable of precipitating one hundred million parts
of casein, a more moderate estimate by Hammarsten places
~ it at 400,000 times. )

Hammarsten! proved that the enzyme present in rennet
differed from pepsin, and according to this authority it has
a specific action upon the casein in milk, splitting it into
paracasein, which is insoluble, and a smaller proportion of
lacto-protein, which is soluble and passes into the whey.

That the coagulation of milk by rennet, although favoured
by an acid, is not due to the generation of acid, was proved
by Berzelius,? and later confirmed by Selim,*? Lehmann,‘
Heintz,° and Voelcker.®

Schreiner’ discovered the remarkable fact that milk which
has been boiled is not coagulated by rennet. This was
difficult to explain, but several years later Fr. Sdldner® gave

1Maly’s “Jahresbu. f. Tierchemie,’’ 1872, II, 118.
2«¢ Tehrbuch der Chemie,” 1840. '
3« Jour. de Pharm. et de Chim.,’”’ 1846, X, 458.
4** Tehrbuch der Phys. Chem.,’’ Leipzig, 1842.
5« Jour. f. prakt. Chem.,”’ 1872, 6, 374.

~ 6 Jour, Roy. Agric. Soc. of Eng.,’’ 1861, 22, 61.
7‘ Chem, Centr,”’ 1878, 588, *
8«D, Landw. Versuchs-Stationen,” 1888, 35, 351.

CASEIN: ITS ORIGIN, PREPARATION AND PROPERTIES. 9°

the solution by showing that rennet was active only in
presence of soluble salts of lime which were present in un-
boiled milk but largely precipitated out on boiling. An
addition of a little alkali similarly causes precipitation of the
lime salts and thus inhibits the coagulative effect of the
enzyme. Milk deficient in calcium salts also requires a
longer time for ‘coagulation by rennet, but this can be
remedied by adding a very small quantity of calcium chloride.
Lindet' expresses the view that the calcium chloride thus
added acts upon the alkaline phosphates and citrates present
in the milk, which are solvents of the casein, with the
formation of insoluble calcium salts, the casein being then
thrown out of solution. The effect of the enzyme is not
immediately perceptible and is influenced very materially by
the temperature. It is most active at 37° C., as shown by
A. Mayer,’ but its action slows down either by cooling or by
further heating; at 25° C. it requires three times as long to
cause coagulation and only 18 per cent. of the casein is curdled ;
at 45° C. the enzyme is again less active; at 50° C. only 50 per
cent. of the casein is curdled, while at 70° C. the enzyme is
permanently destroyed.

The coagulation of milk by rennet has been the subject
of much speculation recently, and several new views of the
mechanism of the process have been put forward. Mellanby?
assumes that the rennet enzyme is adsorbed by the casein
and that the casein-rennet complex is precipitated by the
calcium (bivalent) ions contained in the milk, the amount of
ionised calcium salt required bearing a distinct relation to
the quantity of enzyme adsorbed. Bang* draws the con-
clusion from his experiments that rennet is not per se a

1« Compt. Rend.,’’ 1913, 157, 381.
2« TD), Landw. Versuchs-Stationen,’’ 1882, 27, 27.
3«¢ Jour. of Physiol.,”’ 1912, 45, 345.

4 Skand. Archiy. Physiol.,” 1911, 25, 105-144.

"0 CASEIN.

coagulating enzyme, the actual curdling more nearly re-
sembling the precipitation of protein by neutral salts than
actual coagulation. Alexander‘! expressed the opinion that
the casein in milk is “‘ protected’ or held in colloidal solution
by the hydrophile colloid—lact-albumin—which combination
is destroyed by rennet, the casein particles then coalescing
into larger aggregates, which are then precipitated. Schryver?
draws an analogy between sodium cholate and milk. He
states that when calcium salts are added to sodium cholate
and the mixture is heated a clot is formed. This clotting
being influenced more or less by added salts. Thus salts
which increase the surface tension of water decrease the time
of clotting proportionately to the concentration of the salt.
Salts which decrease the surface tension of water, on the
other hand, decrease the time of clotting up to a certain limit
of concentration, above which the opposite effect is produced,
the time being increased or clotting entirely prevented. This
inhibition of coagulation is regarded as due to the adsorption
of simple molecules of the salt by the complex colloid, which
is, therefore, held in colloidal solution by their power to pre-
vent coalescence.

The same explanation holds good in the case of milk, the
simple molecules of the salts being adsorbed by the casein,
which is thus prevented from coalescing. The addition of
the enzyme removes the adsorbed substances from the sur-
face of the colloid, thus allowing the casein to coalesce and
thus precipitate. Schryver assumes that in milk the condi-
tion of the milk and the clotting are due to four distinct
classes of substances—colloids, calcium salts, simple in-
hibitory bodies, and enzymes.®

Preparation of Casein.—Leaving out of consideration the

1 Proc, 8th Int. Cong. Appl. Chem.,” 1912, 6, 12-14.

2« Proc. Roy. Soc.,” 1913, B 86, pp. 460-481.
3“ Second Report on Colloid Chemistry,” Brit, Assoc., 1919, 100-105.

CASEIN: ITS ORIGIN, PREPARATION AND PROPERTIES. 11

primitive pans, suspended over a wood fire, reference will be
made only to the form shown in Fig. 1, which represents a
pan surrounded by brickwork (a) with an annular flue (0)
between the pan and the brickwork. To the right of the
pan is mounted another, for heating the water, while a port- _
able grate runs along a track (hk), so that it can be rolled
under one or the other pan as may be desired.

When used for heating the water pan a door at (2) fitted
with a damper is closed. This arrangement offers numerous
advantages, the height to which the flame is admitted in the
flue, for instance, being controlled by a damper, whilst the
surrounding brick setting enables the milk-to retain the heat

a

aem|- 32K

Fic, 1.—Heating Pan for the Preparation of Casein.
(K = Milk Pan. W= Water Pan. #'= Portable Grate.)

better than if merely suspended over an open fire. Finally,
the fuel is more fully utilised, since none is uselessly con-
sumed, the excess heat being employed for heating water.
Steam, or even -hot water, can also be used for heating
the pans, a steam pan of this character being illustrated in
Fig. 2. The advantage in this case is that the heating surface
exposed to the steam is very large, which, therefore, utilises
the heat fully. A very useful form of pan is the “ duplicator ”’
(Fig. 3) for casein, jam boiling, and for evaporating or cool-
ing milk, etc. It consists of two copper pans (of one-eighth
to one-twelfth inch sheet copper), mounted in an iron frame,
so that the whole can be tilted. The trunnions.are hollow,

12 CASEIN.

to admit steam on the one side and cold water on the other,
branches from the trunnions entering the jacket space and
terminating in perforated pipes to ensure more perfect dis-

ee Ae TE

Fic. 2.—Steam Pan for Casein.

tribution of heat. D represents the steam valve, W the
water tap, and C the discharge tap. The cold water runs
away through the overflow, Ue.

‘Fia. 3.—* Duplicator’? Pan for Casein.

No special boiler is needed for generating the necessary
steam, as high steam pressure is not required. A very con-
venient steam generator for this purpose is shown at Fig. 4.

CASEIN: ITS ORIGIN, PREPARATION AND PROPERTIES, 13

Where water can be drawn from the mains the boiler is filled
through the pipe (a). The steam leaves through the pipe
(B), which can be fitted with several branch cocks, as shown
in the figure leading to the different pans. The pipe (0),
which extends to within four inches of the bottom of the
boiler, serves a dual purpose. In the first place, it acts as a
safety valve, the water being forced out if the internal pressure

Ta
YY

> ’
? ave
ox t= ¢

are NA \N\
f

Fic. 4.—Steam Generator.

(V = Pipe to Casein Pan. A = Steampipe. H = Washer.
D = Fodder Steamer. r+ = Extra Branch.)

becomes excessive owing to obstructions in the outlet pipes.
Secondly, if the boiler is not kept properly filled steam will
escape through this pipe as soon as the water-level sinks
below the lower orifice, an indication being thus given that
the water requires replenishing. The piece marked (d) is a
ground block of iron, fitting into a manhole, through which
the boiler is cleaned out. It also acts as a safety-valve

14 CASEIN.

in the event of the pipe (c) getting choked. Hot water can
be drawn from the boiler through the tap (f), which may also
be used for the introduction of flushing water when the
boiler is being cleaned. The pipe (g) is employed as an
overflow in filling the boiler, to prevent over-filling, and
indicates when sufficient water has been run in.

When the milk to be curdled has been raised to the
proper temperature in one of the pans just described, it is
treated with the rennet. No immediate change is apparent,
but after some little time the milk begins to curdle, having
thickened just before, and the precipitation of the casein is
soon complete. At a temperature of 95° F. one part of good
rennet is sufficient to curdle 10,000 parts of milk within forty
minutes, whilst two parts will effect the same result in half
the time or curdle double the quantity in the same time.
For a given temperature and a definite quantity of milk the
time required for coagulation varies inversely with the amount
of-rennet used.
~ Rennet which has been used once looses its power almost
entirely, it being difficult to curdle a fresh batch of milk with
the whey from the previous one. From this it follows that
the curdling of milk by rennet must be regarded as a very
protracted chemical process, which does not become apparent
until it has proceeded to a certain stage. The stronger the
action of the rennet, and the sooner the casein is thrown
down, the more powerful the contraction of the curd and the
larger the volume of whey expressed. ‘This means a reduc-
tion in the residual water in the curd and an increase in its
final dryness and firmness. Hence the manner in which the
rennet acts is of considerable importance in its effect on the
character of the casein.

This latter is also influenced by the quantity of rennet
used, the temperature at which it is allowed to act, and,
finally, by the character -of the milk, or, rather, the casein

CASEIN: ITS ORIGIN, PREPARATION AND PROPERTIES. 15

therein. The character of the casein reacts on the influence
of the rennet, and the same applies to the reaction of the
milk, an acid reaction favouring the working of the rennet,
whilst an alkaline reaction retards or annuls it. In the case
of normal milk, which has an amphoteric reaction, the action
is intermediate between these two extremes. The increased
effect in the case of sour milk is explained by the presence
of a larger quantity of soluble salts of lime, which are essential
to the action of the rennet. With an alkaline reaction the
proportion of these salts is lower, and, consequently, the
rennet is less efficacious. Cases have been known in which
the imperfect action of rennet—resulting in the milk refusing
to curdle at all—has been traced entirely to the poverty of
the milk in soluble lime salts. Old milk, again, takes longer
to curdle than when fresh; and the percentage of water
present also plays a part. Milk that has been boiled, or
heated to 167° C., is more difficult to curdle, and will not do
so at all in some cases owing to the alteration effected in the
lime salts by heat.

Lactalbumen and lactoglobulin are coagulated by boiling,
in the same way as albumen and globulin. Casein, on the
other hand, forms a skin on the surface of the milk due to
evaporation, but does not coagulate below 266° F. in a closed
vessel. The formation of the skin is prevented by stirring, ©
or by heating the milk in an enclosed space or one saturated
with steam. Se

As already mentioned, the decomposition of milk can be
effected by other substances, particularly acid and acid salts ;
though these are rarely used, since the chief use of casein, in
the form of cheese, is as a foodstuff.

The coagulation of milk furnishes two chief products:
the curd, containing a larger or smaller proportion of fat,
proteids, and lactic acid; and the whey, containing the solu-
able salts of the milk, together with some finely divided curd,

16 CASEIN.

lactic acid, milk sugar, etc. Strictly speaking, the whey can
be differentiated into cheese-milk and whey, the former term
being applied to the liquid remaining after the separation of
the curd, whilst whey, in the narrower sense, is the residue
left after the removal of the whey-butter and whey-cheese.
The whey proper is used as a beverage, in baking, for feeding
pigs, and also for the recovery of milk sugar (for alcohol or
vinegar), and the preparation of fermented liquors, such as
whey-champagne and whey-punch. The two classes of whey
have, according to Fleischmann, the following composition :—
Cheese-milk. Whey.

Water : ; : : ; ; 93°15 93°31
Fat. 4 ; : ; : ; 0°35 0°10
Proteids , : 5 ; : : 1-00 0°27
Milk sugar and lactic acid . : ; 4°90 5:05
Ash . : ‘ ‘ . : ; 0-60 0°47

The casein separated from milk is termed ‘‘ curd,” and is
subjected to further treatment, mainly with a view to reducing
its water content when cheese-making is in question. If, on
the other hand, it is to be used for technical purposes, it must
be thoroughly freed from the residual whey by repeated
washing with hot or cold water, and, finally, more or less
thoroughly pressed (according to the purpose in view) to expel
the water.

The spontaneous and artificial coagulation of milk has
been dealt with by Prof. Pokorny (“Chemiker Zeitung ’’) as
follows: “It is known that milk left to stand becomes sour
and curdles spontaneously as the result of the formation of
acid. This cause is demonstrated by the fact that fresh milk
can be curdled by the addition of lactic or other acid, the
same result being produced by acid salts.” When milk is
allowed to stand at the ordinary temperature it becomes acid
owing to the generation of lactic acid due to bacterial action
on the lactose or milk sugar also present, and as soon as the
acid reaches a certain concentration the milk curdles or forms

CASEIN : ITS ORIGIN, PREPARATION AND PROPERTIES. 17

a soft jelly. ‘The reaction which takes place is not a simple
one, since gases and other products are also formed, but
the chief change is due to the absorption of the elements of
water as follows :—

C.sH,.0,, + H,O ey 4C,H,0O..
Milk sugar. Water. Lactic acid.

The presence of an organism during lactic fermentation
was first discovered by Pasteur,| who also showed that the
addition of this organism to sweet sterile milk caused it to
rapidly become sour. ‘The organism was isolated in the form
of a pure cultivation by Lister,? who used the now well-
known method of dilution for the purpose, and named the
organism Bacterium lactis. Hueffe* also prepared pure
cultivations and examined the organism very closely, the
name given to it by him being Bacillus acidi-lactici.4

Fresh milk treated with acetic acid is coagulated almost
instantaneously when the amount of acid used is large,
though with small quantities of acid some little time elapses
before the flakes of casein can be observed adhering to the
walls of the test-glass on shaking. Sulphuric acid, being a
strong mineral acid, coagulates milk at once when added
in the proportion of 5 per cent. (e.g., 10 c.c. of 10 per cent.
sulphuric acid to 20 c.c. of milk).

For commercial purposes either acetic or hydrochloric
acid are used. The nature of the acid is not important
in the clotting, which depends upon the hydrogen ion con-
centration, the time required for clotting, according to
Michaelis and Mendelssohn,° being proportional to the latter.

1«* Compt. Rend.,” 1857, 45, 416.

2¢ Quart. Jour. Micros. Sci.,” 1873, 13, 380.

3** Chem. Centr.,’’ 1884, 315.

4* Technical Mycology,” 1910-11, by Dr. Franz Lafar.
5 « Biochem, Zeit.,” 1915, 58, 315.

2

18 CASEIN.

Alleman?‘ gives the optimum hydrogen ion concentration as
2°5 x 10~° and the minimum 1°3 x 1075 —

The first treatment of the curd in cheesemaking is
designed to remove the enclosed whey, the curd being
vigorously stirred or broken by hand with a curd-breaker
or similar instrument. Curd mills are also used, these con-
sisting principally of a grid or lattice of galvanised iron rods,
between which rotates a shaft armed with teeth. When the
shaft is turned by means of the handle, the curd introduced
through a feed hopper is pressed between the rods by the
teeth, and thoroughly broken up or squeezed. The broken
curd is then stirred to a uniform pulp with a little water in a
large vat, and passed through a sieve or mill, after which
sufficient water is added to form a milky liquid. This is left
for the curd to settle down, and sieved to drain off the liquid ;
or in large dairies it is put through a centrifugal separator.

All centrifugal machines are driven by steam or elec-
tricity, by means of intermediate gearing, or else by special
driving mechanism, and have to be run at high speed, which
in turn entails solidity of construction. For reasons of
safety, therefore, the maximum permissible load and speed of
rotation should be conspicuously posted on’ each centrifugal
machine, and machines of this kind driven by attached
motors should be provided with a speed indicator marked
with the maximum permitted speed. These machines are
either driven from above through a second motion mounted
on uprights forming part of the machine, or else from below,
the motion being transmitted to the vertical shaft, this latter
method being now almost exclusively employed. Though ~
both systems entail good construction and very careful super- -
vision in working, this is particularly the case with overhead
driving. They also require very strong foundations, the
contents of the drum are very liable to contamination by the

i« Biochem. Zeit.,” 1912, 45, 346-358.

CASEIN: ITS ORIGIN, PREPARATION AND PROPERTIES. 19

lubricating oil, and the accessibility of the drum is greatly
reduced by the main shaft passing through it. On the other
hand, the machines take up Jess room than those driven from
beneath. A typical centrifugal machine with bottom driving
is that shown in Fig. 5, for which the maker claims the
following points of superiority: (1) Perfectly even and noise-
less running, combined with low cost of up-keep ; (2) absence
of any masonry foundation, which is replaced by a strong
wooden frame, enabling the machine to be set up in any
convenient place, even in upper storeys ; (3) small consump-

©
|
|

J
oa

Fia. 5.—Section of, Centrifugal Machine with Bottom Discharge.

tion of motive power, drum perfectly clear inside; (4) driving
mechanism situated under the drum, preventing any con-
tamination of the contents by dropping oil; (5) careful and
solid construction of the various parts, with minimum wear
and tear; (6) high speed combined with perfect safety.

The drums are constructed and arranged in such a
manner that the contents are expelled with perfect regu-
larity. They are usually made of sheet copper, though for
other purposes use is made of steel, wrought or cast iron, and
aluminium, brass, bronze, nickel plate or. porcelain, or they

*

20 CASEIN.

are coated with vulcanite or enamel, as well as tinned, lead-
lined, galvanised or silver-plated. A vulcanite lining is
recommended for all materials which are injured by contact
with metal, or where the metal used cannot properly resist
the action of acids, etc. For these purposes vulcanite is
superior to porcelain or earthenware linings on account of its
lightness, a machine coated with it can be run at the highest
speed permissible for centrifugal separators, whereas with
earthenware the heavy weight necessitates low speeds. The
same applies to lead-lined drums, in which, owing to
technical difficulties, a uniform lining cannot be secured with
sheet metal less than about one-eighth inch thick, thus
making the drum so heavy that it cannot be run without
danger at the ordinary speed. 3

The washing and draining of the curd is repeated several
times, until the washings run away clear, the curd being
finally drained in the separator and pressed, if necessary,
to bring it to the proper state of dryness. In this form it
can be sent out for some uses, in which the presence of
the residual moisture is not detrimental; otherwise it is
thoroughly dried for conversion into powder.

The drained curd may be dried on trays in drying-rooms,
heated by a current of hot air to facilitate the removal of the
moisture, or else is treated in special forms of apparatus, a
few of which will now be described. The first of theseis the
drving cylinder, heated either from inside or outside, or both,
and rotated to keep the contents in constant motion. The
cylinder may be provided with a shaft carrying paddles or
similar devices rotating in a fixed cylinder, or with the
former stationary while the cylinder revolves; or the two
may move in the same or opposite directions. The best type
of drying cylinder is one containing no moving internal parts,
since these parts are liable to become obstructed, and even
broken, by the material under treatment when in large

CASEIN: ITS ORIGIN, PREPARATION AND PROPERTIES. 21

masses; and they also break the material down too small
in some cases. The rotary movement of the cylinder or of
the shaft not only keeps the material in a constant state of
agitation, and thus greatly accelerates drying by presenting
fresh surfaces for evaporation, but it also gradually moves the
material onward in the cylinder. The operation, therefore,
proceeds continuously, in the same way as in a drying flue,
though more rapidly on account of the constant stirring,
yielding a product of perfectly uniform dryness throughout.
The progressive movement of the material is effected in
various ways, either by means of an internal rotating shaft,
fitted with spirally mounted arms, which therefore acts like
a worm conveyer, or else by mounting the drum with one
end higher than the other. The latter effect may be also
obtained by the use of a conical casing, the shaft being
mounted horizontally, though the cylindrical form, with the
shaft tilted at an angle from the horizontal, is preferable, on
account of lower cost and greater ease of manufacture. In
this system the central shaft and arms are unnecessary, the
drum being actuated by a toothed crown round the outer
edge, driven by worm or cog gearing. Worm gearing is
preferable, being more easily fitted and giving the requisite
slow movement. without any troublesome reducing gear when
the shafting is run at the ordinary speed. In view of the
small power needed to drive the cylinder, no objection on the
score of useful effect applies to the use of worm gearing.

The interior of the cylinder must be fitted with blades,
which lift up the material under treatment and allow it to
fall again slowly and in small quantities, so that every
particle is repeatedly exposed to the surrounding warm air.
At the same time, the material is always lifted perpen--:
dicularly to the axis of the drum and falls vertically, thus
describing a spiral line, the pitch of which depends on the
slope of the drum axis towards the horizontal. Hach

22 CASEIN.

revolution of the drum, therefore, moves every particle of the
contents spirally onward, the rate of advance being regulated
by two factors—the speed of the drum and the axial slope.
If the latter be nil, the pitch of the aforesaid spiral will be
also nil, and the material will be turned over but not moved
forward: and in proportion as the axial slope is incréased or
diminished, so also will the material in the drum move
faster or slower. Since the same drum is used for drying
different materials at different times, or for treating the same
material containing different percentages of moisture, it is
advisable to make provision for working in a corresponding

HS),
am

Fia. 6.—Rotary Drying Cylinder.

manner, which can be most easily done by making the axial
slope adjustable. In this manner the onward movement of
the material can be accelerated or retarded as required, and
the drying process carried on in a uniform manner at the
smallest expense. A fewinstances of typical drying cylinders
will now be given, the details of which can be modified
according to requirements.

Fig. 6 represents a horizontal drum (qa) fitted with a shaft
(6), the arms (c) of which move the material onward. The
cylinder is of the fixed type, and is jacketed for steam heating.
The liberated moisture escapes through the discharge outlet.

ITS ORIGIN, PREPARATION AND PROPERTIES. 23

CASEIN :

The Passburg drying apparatus (Fig. 7) 1s fitted internally
with a rotary system of tubes, which also serves to mix,

advance, and dry the contents of the drum. The heating

(‘eoglIQ esreyosiq = VF
‘JOTING WRo}G OSB = YF “UOISsUIpY UlBeyg = CT ‘dig poag = @ ‘yneyxg anode, = gy)
‘roliq, Aveqoy 8,Sinqsseg—"), ‘D1

SS eee

It may be heated either by live or exhaust steam.
Fig. 8 shows the Patent Agitator Vacuum Drier made

efficiency of this apparatus is high resulting in great drying
by Geo. Scott & Son (London), Ltd. In this form of drier

capacity.

D4 aS CASEIN.

the material is kept agitated by means of curved blades
fixed to a central shaft which is caused to revolve by means
of toothed wheels. The material is thus kept on the move
and new material constantly exposed to the heated surfaces,

Fic. 8.—Patent Agitator Vacuum Drier. George Scott & Son, Ltd.

at the same time the breaking up of the material allows the
moisture to escape. The vacuum is obtained by the pump
shown in the centre of the illustration.

These rotary driers are suitable where economy in the
first cost 1s the prime consideration. For some materials

CASEIN: ITS ORIGIN, PREPARATION AND PROPERTIES. 25

they have also a decided advantage over the shelf type of
drier.

The vacuum drier, shown in Figs. 9 and 10, made by
Geo. Scott & Son (London), Ltd., consists of a cast or
wrought-iron case, which can be hermetically closed by a
door at the front. The chamber is divided into a number of
superimposed hollow steam shelves, fitted with proper con-
nections for admitting and discharging the heating fluid,
and constructed to stand a working pressure of 5 atmospheres.
These shelves support the trays holding the material to be
dried. When the rubber-shod doors have been closed, a
vacuum of 720 mm. mercury gauge is produced in the chamber
by means of an airpump, the shelves being meanwhile tra-
versed by the steam or other heating fluid employed. In
consequence of the vacuum the water in the material to be
dried is vaporised readily and quickly at a comparatively
moderate temperature (about 104° F.), so that drying is soon
effected. In fact, the apparatus will dry in a few hours, and
without the slightest risk of overheating, materials which
being difficult to dry take several days when treated by other
processes, even if they can be dried at all. The apparatus
is easily and conveniently fed, and does its work in a clean
and efficient manner. The temperature is regulated by
simply adjusting the steampipe valve. When hot water is
used for heating and an efficient vacuum is obtained by
means of a vacuum pump, the water can be vaporised at
68° F.

Purifying the Curd~—One hundred parts by weight of
well-pressed curd are stirred to a pulp with 50 parts of water,
and, in order to remove lactic acid and butter fat, it is
steamed for twenty-five to thirty minutes in a wooden vat
together with about 150 parts of a 1 per cent. solution of bi-
carbonate of soda. | |

The vat must be of ample capacity, on account of the

26

CASEIN.

Fias. 9 and 10.—'Iray Vacuum Drier.

George Scott & Son, Ltd.

CASEIN: ITS ORIGIN, PREPARATION AND PROPERTIES. 27

frothing that occurs. After heating, the mass forms a thin
milky liquid, which is transferred to a separate vessel to cool,
and is then treated with dilute nitric acid until a small sample
no longer exhibits traces of a precipitate. As a rule 4 to #
per cent. of 40 per cent. nitric acid, mixed with 4 parts by
weight of water, will be sufficient. The casein separates out
from the milky liquid on standing and falls to the bottom.
The supernatant fluid is run off, the casein rinsed with fresh
water, left to settle, the water decanted, and the washing re-
peated till the effluent water is perfectly neutral.

Fic. 11.—Jchnson’s Filter Press.

To convert the casein into a dry powder it is laid on filter
cloths to drain and afterwards pressed, preferably in a filter
press (Fig. 11), this operation being followed by drying on
trays in drying chambers at a temperature of 120° to 140° F,
The finished product can either be worked up at once or
may be stored in a dry place for use later. The small re-
sidual quantity of butter fat in the casein could be entirely
removed by digestion with benzol or with an ether-alcohol
mixture, but owing to the troublesome nature of the process

J ae CASEIN.

it is seldom practised. One hundred parts of curd furnish
45 parts of purified casein, free from lactic acid and butter
fat. The moist material can be immediately converted into
a good glue by mixing it with 25 per cent. of distilled water
and 1 to 4 per cent. of bicarbonate of soda in a mechanical
stirring apparatus working at fifteen to twenty revolutions
per minute. Afterwards another 25 per cent. of distilled
water is added to complete the solution, and the whole is
left to stand for five to six hours. At the end of that time
the glue will be pliant and fit for use. An antiseptic is
added to prevent mould.

A very similar process to this is claimed by R. Eilersen
of Copenhagen (U.S. Pat. 1,126,429, March 19, 1914) in the
preparation of casein from buttermilk, the buttermilk being
heated to 40° to 65° C. until the curd separates. The latter
is washed with cold water, and then a quantity of water
about equal to the whey is added and sufficient bicarbonate
of soda to dissolve the curd. The liquid is filtered to remove
any butter fat and albumin which remain undissolved, and
‘sufficient hydrochloric acid is added to render the liquid acid,
whereupon the casein is precipitated, and, after washing with
water is dried. |

Owing to the difficulties of transport, it is in many cases
impossible to distribute milk in a fresh condition. By con-
verting it into casein, a dry non-decaying substance that may
be packed in boxes or bags, it may be carried with ease, and
it finds a ready sale for use as a substitute for celluloid, over
which it has the advantage of not being inflammable. For
some years a profitable business has been conducted at
Anand in the Baroda State in the production of casein for
export. The process resembles the manufacture of cheese.
The skimmed milk is coagulated by rennet, precipitated by
hydrochloric acid, and separated in a centrifugal filter. The
result is a whitish or yellowish mass which is the casein of
commerce. There are several ways of separating it, one of

CASEIN: ITS ORIGIN, PREPARATION AND PROPERTIES. 29

the most recent being by a current of electricity, which is
said to be the cheapest where current from wind or water
power is available.

Vegetable Casein.—At a meeting held at the Chemists
Club, New York, Dr. Oskar Nagel, read a most interesting
paper on vegetable protein, in which after describing the
process used for the extraction of vegetable albumin, he pro-
ceeded to discuss the method of extracting casein from vege-
table sources. He said: for making vegetable casein, which,
in its solubility, viscosity, and other properties, is equal to milk
casein, I use soy-bean, which, until now, has not been used
in chemical industries. This seed, being the richest casein-
containing seed produced by nature, and at the same time
exceedingly cheap, can be imported from China in any
quantity desired. It contains 12 to 18 per cent. of an
excellent edible oil, largely used in the Orient, and 30 to 40
per cent. casein. The richness in fat decreases the expenses
of the process considerably. For making casein the finely-
ground beans are extracted nearly completely by means of
benzine or any other solvent in an apparatus ordinarily in
use for that purpose. Hydraulic presses may also be em-
ployed for removing the oil, but in this case the residuum
will naturally be richer in fat than if worked by extraction.
The residue, freed from benzine, is digested at a temperature
of 80° to 35°, with a 5 per cent. solution of sodium carbonate
for several hours, solution being assisted by means of stirrers.
The solution is then filter-pressed.

The casein is now precipitated from the filtered alkaline
casein solution, with continuous stirring, by means of rennet
or a 5 per cent. solution of hydrochloric acid. The precipitated
casein is filtered, washed, and dried in a steam-heated room
at as low a temperature as possible. The benzine is removed
in the extraction apparatus mentioned above, from the solu-
tion of oil in benzine, obtained in the first zeus of the process,
and used over again.

CHAPTER ITI.

VARIOUS METHODS OF PREPARING CASEIN.

In order to obtain white casein, free from the yellow tinge
attaching to that prepared with sulphuric acid, several dif-
ferent acids are used in succession as precipitants, a method
which also has the advantage of cheapness. The best plan
is to first throw down the casein as curd, with sulphuric acid,
then dissolve this curd in alkali, and reprecipitate with acetic
acid. According t6 the German patent specification of R.
Hatmaker (dated May, 1901), about one and a half parts by
volume of sulphuric acid (density 66° B.), diluted with seven
of water, are sufficient to precipitate the curd from 1,000 parts
of milk. If the operation is performed at a temperature of
100° to 120° F., the curd will come down as large and solid
lumps, which must then be thoroughly washed with cold
water. The curd from the above quantity of milk can be
dissolved in 350 parts of a 5 per cent. solution of bicarbonate
of soda, the process being accelerated by warming the whole
to 100° F. Acetic acid of about 29 per cent. strength is used,
and is added slowly till all the casein has been thrown down
and the separated aqueous liquid is perfectly clear. After
this liquid has been drawn off the casein is thoroughly washed
with cold water.

A. Hall recommends that the milk should be curdled with
hydrochloric acid, the resulting casein being heated to such
a degree that the contained acid volatilises. A current of air
is also passed through the mass. This would, however, lead ~

to a certain amount of decomposition.
(30)

VARIOUS METHODS OF PREPARING CASEIN. 31

According to A. Spitteler, the alkali used in preparing the
casein should be replaced by an alkali carbonate, when a
colourless, tough casein is desired. In this case the reaction
proceeds more gradually. Should a transparent product be
desired, the separated substance should not be removed from
the solution until the latter begins to be transparent.

K. Ruprecht states that the following method is employed
for producing technical casein :—

Skim milk is placed in a vat fitted with stirrers consisting
of a vertical shaft carrying several horizontal blades. These
stirrers are set in motion so as to bring the whole of the
liquid into rapid rotation, and dilute hydrochloric or acetic
acid is run in by degrees. The casein begins to separate 1m-
mediately in the form of tender white flakes, and the quantity
of acid used is strictly limited to the amount necessary for
precipitation ; while continuing the stirring a sample of the
liquid is taken, filtered, and the clear filtrate tested with a
little of the acid. If it remains clear, the whole of the casein
has been precipitated.

The liquid is then allowed to stand until all the casein has
settled down, whereupon the clear liquid may be syphoned
off by means of a rubber tube fitted with a glass funnel, the
mouth of which is covered with fine gauze, and is lowered
into the liquid until it reaches the curd, which is kept back
by the gauze sieve. The separated liquid contains albuminoid
compounds, salts, and the whole of the milk sugar present in
the milk, for the recovery of which it can subsequently be
treated.

The caesin left in the vat is stirred up with water, left to
settle, the water run off, and the operation repeated two or
three times. The casein, thus sufficiently purified, is placed
in strong filter cloths, which are placed between wooden
plates in a screw press. Pressure is applied gradually and
so long as any liquid continues to drop. The casein is next

82 CASEIN.

taken out of the cloths, and as it still contains a considerable
amount of moisture, it is broken down into small lumps,
which are spread out thinly on cloths stretched on frames.
These are placed in a drying-room, kept at a temperature of
about 86° F., until the casein is perfectly free from water and
will crumble to powder under the pressure of the finger.

When thoroughly dry, casein can be packed and stored
in a dry room for an indefinite period, without undergoing
alteration. On the other hand, the presence of even the
smallest quantity of moisture enables micro-organisms to
develop in the casein which cause putrefaction of the whole
mass. The following method is very suitable to adopt in
packing casein. The dried product is spread on cloths and
sprayed over with a small quantity of pure 95 per cent.
alcohol, after which it is immediately packed tightly into
square cardboard boxes, with a strip of paper pasted round
the edge of the ld when closed. The minute quantity of
spirit introduced into the casein volatilises, forming an atmos-
phere in which no micro-organisms can develop.

Casein prepared in this manner will gradually swell up,
in very dilute solutions of caustic alkalies or their carbonates,
to a transparent mass, and eventually pass into solution.
The same result can be obtained without drying the casein,
the solution keeping well and having the advantage of being
ready for use without waiting for the solid casein to swell
and dissolve. With this object the washed casein is mixed
in the vat with sufficient water to form a thick cream, to which
is added about a quarter of a pint of aqueous ammonia per
pound of dry curd present. This can be calculated approxi-
mately from the weight of milk taken in the first place, the
average casein content being 3°2 per cent. After adding the
ammonia the vat is covered up and the stirrers kept in motion
for some time; whereupon, if sufficient ammonia has been
used, the casein will be found to have dissolved to a clear

VARIOUS METHODS OF PREPARING CASEIN. 33

viscous liquid, with a faint yellow tinge. On the other hand,
if the liquid is cloudy, more ammonia should be added, with
stirring, until the solution becomes clear. The finished solu-
tion is then run into glass bottles at once and hermetically
sealed. After prolonged standing, a small deposit of undis-
solved casein may settle down in the bottles. This clarified
solution when poured out on glass, dries to a hard, colourless
and insoluble mass, with a high lustre, on which account it
serves as an excellent lacquer. Printing colours that are not
sensitive to the action of ammonia may be mixed and printed
with the liquid, the casein becoming insoluble on evaporation,
thus fixing the colour on the fabric.

A patent on the following lines, for preparing fat-free
~ easein from skim milk, was taken out by Mierisch and Dr.
Eberhardt. Ordinary “separated”? milk contains 0°2 to 0°3
per cent. of fat, and if used for the preparation of casein, yields
a product containing 6 to 8 per cent. of fat. The usual
method of removing this fat is by extraction with fat solvents
or repeated solution in alkalies and reprecipitation by acids ;
but in the patented process the skim milk is mixed with
alkali, warmed and centrifugalised to expel the fat, the liquids
being afterwards treated with acid, in the usual manner, to
throw down the casein. For example, 100 gallons of skim —
milk are mixed with a solution of 2 to 4 lb. of caustic soda,
the whole being warmed to 100° to 112° F. and put through
the centrifugal separator until no more fat passes over. The
casein is next thrown down with dilute sulphuric acid and
collected, washed, pressed, and, if necessary, dried. The
product thus formed will satisfy practical requirements in
respect of freedom from fat.

Riegel’s method of precipitating casein with ethylsulphuric
acid is intended to replace the use of acetic acid, lactic acid,
and sulphuric acid for this purpose. The acid in question

shares with sulphuric and acetic acids the property of
| see 7

34 CASEIN.

precipitating the casein in an undecomposed, compact, and
non-mucilaginous form, but possesses the advantage that,
owing to the ready solubility of its lime salt, the casein is
obtained almost free from ash by the first precipitation. At
the same time the casein is poorer in germs than when acetic
acid or lactic acid is used, the inverting action on the milk
sugar at the same time being smaller. Crude ethylsulphuric
acid is used, this being prepared by rapidly mixing equal
volumes of concentrated sulphuric acid and strong alcohol,
and leaving the mixture to stand for several hours in a warm
place. : 7

To obtain soluble casein in the dry commercial state, the
curd is thrown down from the milk, washed to remove whey
and any excess of precipitant, dried at a moderate tempera- —
ture to preclude risk of burning, granulated, and allowed to
absorb a small quantity of dissolved alkali by rapidly stirring
the two together. Finally, the granulated alkaline product
is dried in accordance with American patent 664,318.

Szekely’s patent (German patent 126,423) relates to the
separation of milk into casein and whey by means of car-
bonic acid. For this purpose, sweet new milk, cream, skim
milk or buttermilk is placed in a closed vessel, warmed
somewhat above 86° F., and a sufficient amount of carbonic
acid gas is forced in under pressure to precipitate the whole
of the casein when well shaken or stirred.

_ To.overcome the differences in skim milk in the separa-
tion of the casein, C. H. Bellamy of Philadelphia adds to the
casein in the preparation of casein glue an alkali arsenate
(e.g., NagHAsO,). This addition is stated to increase the
adhesive power of the glue, preserves it from putrefaction,
and forms a kind of mordant, acting as a binder between the
paper, the casein glue and any added colouring matter.

Pure casein, free from ash, is obtained by precipitating
1,000 parts of cold milk with 2°9 parts of acetic acid which

VARIOUS METHODS OF PREPARING CASEIN. 35

leaves the bulk of the lactalbumen in solution. The filtered
and slightly -washed precipitate is purified by repeated solu-
tion in water containing sufficient commercial ammonium
carbonate to furnish a decidedly alkaline reaction, the filtered
solution being then neutralised with acetic acid. According
to Béchamp, one part of this pure casein dissolves in about
1,000 parts of water, as well as in alkalies and-acids.

The Hoppe-Seyler method of preparing casein, as
practised by Hammarsten, consists in treating milk with
acetic acid, and dissolving the precipitate in the minimum
quantity of dilute ammonia or sodium carbonate, an alkaline
reaction being guarded against. This operation is repeated,
the casein being then treated with alcohol and ether to com-
pletely eliminate the contained fat, a second treatment with
acetic acid and soda completing the purification. Provided
a strongly alkaline reaction is avoided, the casein is not
decomposed. The removal of fat can be facilitated by em-
ploying skimmed milk in place of new milk.

According to another report, pure casein is obtainable by
diluting milk with four times its own volume of water, and |
then adding sufficient acetic acid to bring the acid content
of the mixture to 0:075-0-1 per cent. The precipitate is
purified by trituration under water, and then immediately
redissolved in very dilute potash, followed by reprecipitation
with acetic acid. The casein is washed with water, rubbed
_ down fine with 97 per cent. alcohol, drained and washed
with ether.

- Besana gives the following.instructions for the prepara-
tion of casein for technical purposes :-— .

Skim milk from the separator is heated to about 95° F.
in a cheese vat or similar vessel, direct steam being used if
necessary. It is then treated with about 3 parts per mil.
of crude hydrochloric acid, previously diluted with 5 to 6
volumes of water, whereby it is curdled, the whey being

36 CASEIN.

drained off and the curd spread out in a thin layer on a
sloping table to cool. This done, the mass is washed with a
spray of cold water or churned with water, which is drawn
off after the curd has subsided. After removing a further
quantity of water by pressing the curd in a weighted sack
or in a press under moderate pressure, the product, which is
still moist, is comminuted in a curd mill and is ready for
sale in the damp state.

Casein, in the form of powder, is the kind usually re-
quired for technical purposes. Various forms of drying
apparatus may be used, such as the hot-air apparatus for
drying vegetables or heated drying chambers fitted with
frames for supporting superimposed trays made of strong
canvas, permeable to moisture. These hot-air appliances
‘consume a considerable amount of fuel and are troublesome
to manage unless fitted with expensive mechanical stirring
or turning devices, the constant turning and breaking down
of the casein being necessary. At the same time a constant
drying temperature, between 122° and 175° F., must be
maintained. For this purpose the following arrangement
has proved very satisfactory and cheap, besides enabling the
heat to be efficiently utilised. ‘Two small brick walls, about
a foot high, are built, without foundations, 40 inches apart,
each being topped by a coping of wood 6 inches square.
The coping is surmounted by a thick strip of damp millboard
about 2 inches wide, and this in turn by plates of sheet iron,
40 inches by 80, and } inch thick, fastened down by screws,
so as to form a long horizontal flue 40 inches wide and 12
high. Where the ends of the iron plates join they are
supported by wooden traverses to which they are screwed
with an intervening layer of millboard as in the case of the
copings. The two ends of this flue are closed by brick walls
through one of which exhaust steam is introduced, whilst an
opening in the other enables the steam to escape into a small

“VARIOUS METHODS OF PREPARING CASEIN. 37

chimney. ‘The flue should have a gentle slope towards this
end so that the condensed moisture may drain away. The
casein may be dried very quickly on these iron plates by
spreading it out on the farther end and turning it over with
wooden shovels towards the hotter end. Unless erected
indoors, the flue must be covered with a wide roof to protect
the plates from rain. By means of this simple appliance,
large quantities of casein‘can be dried in a short time, the
only precaution necessary being to protect it from over-
heating by vigorous shovelling and breaking down the lumps,
the flow of steam being also checked if found desirable.

By this means, 100 parts of skim milk will yield about 84
parts of damp or 33 parts of dry casein. This is put on the
market as ‘‘ technical casein’”’ or ‘‘lactarin’’. it is soluble in
alkalies but insoluble in water unless the latter receives an
addition of 10 fer cent. of some alkali (e.g., soda, borax, or
ammonia). The dry casein still contains about 10 per cent.
of moisture, which constitutes one of the factors determining
the quality of the product, though less important than the
appearance and odour. The latter must on no account be
ammoniacal, but should recall that of fresh milk, and the
colour must be pure white. The purer the colour and the
more agreeable the smell, the higher its value.

Soluble casein is obtained from the moist product by dis-
solving the same in an alkali (caustic potash or soda, ammonia,
lime water, or baryta water), or in an alkali salt (carbonate of
potash or soda), and evaporating the solution at a moderate
temperature. ‘This soluble casein is rarely prepared in dairies,
since the industrial consumers of the article can make it
more easily and cheaply themselves from the moist or dry
product. On this account it is usual to specify the manner
in which the moist casein is to be prepared. Consequently,
when these particulars are specified in the contract, the casein-
maker will do well to adhere to the instructions given, and

38 CASEIN.

not to employ some other method of preparation that may
seem preferable to him, or he may conflict with the objects
and views of his customer.

Another method of preparation, recommended by Just, is
used in America, furnishing a light, dry, porous product.
Although similar methods have been employed in Germany
for some years, the inventor obtained a patent in that country,
the specification of which reads as follows: ‘‘A process for
preparing milk casein in a light, dry, porous form, consisting
in distributing a dilute aqueous solution of casein in a uniform
thin layer over a suitable surface previously heated to over
200° F., whereby the casein is dried, the operation being per-
_ formed under ordinary atmospheric pressure”. ‘The following
modification is also described in the specification, but is not
protected by the patent: Twenty-five gallons of water heated
to 105° to 110° F. and containing 1 to 14 lb’ of carbonate of
soda in solution, are used to dissolve 175 lb. of moist casein
or 119 lb. of dry casein, with continued stirring. Two metal
cylinders, mounted so close together that nothing thicker
than a strip of paper can pass between them, are rotated in
. opposite directions and heated by steam at a temperature of
212° to, 220° F., the dissolved casein being allowed to flow
between them. The liquid dries immediately, and the thin,
brittle layer of dried material is scraped or brushed off the
cylinders, whilst, if pressed through a hair sieve, it furnishes
a fine, soluble casein powder.

This method is at all events cheap and simple, yielding a
good, staple product, provided the fat and milk sugar have
been properly eliminated. The granting of the German
patent took two years, a sign of the tenacity with which the
inventor fought his case, though such a claim as that set
forth above is very little protection, as it is difficult to see
where the novelty comes in.

According to a written communication from the inventor,

VARIOUS METHODS OF PREPARING CASEIN. 39

the process has been worked in America on a large scale since
March, 1903, one factory treating 260,000 lb. of skim milk
daily, whilst a second factory began operations in October,
1903.

J: Ricard and C. E. Riche (French patent 364,635, March
27, 1906), dispense with any chemicals, stating that hydrated
casein heated to 100° C. becomes sufficiently plastic to be
rolled out into thin films, and is dried between two cylinders
revolving in opposite directions or on one cylinder only,
heated at 100°-110° C. The casein forms a thin film, which
is removed by a scraper and can be readily pulverised.

Manufacture of Casein.—(H. V. Dunham, Bainbridge,
New York; United States patent, 897,885, Sept. 8, 1908.)
A process for producing a casein compound suitable for
coating, which consists in curdling milk with commercial
hydrofluoric acid diluted to such an extent that it has
no appreciable corrosive action upon glass, and then separ-
ating the precipitated casein from the whey. A process of
producing a casein compound suitable for coating, which
consists in heating milk and mixing commercial hydrofluoric
acid therewith, in the proportion of one pint to one quart of
acid to one thousand quarts of milk and then separating the
casein from the whey. A solution for sizing purposes con-
sisting of approximately 94 per cent. of such casein, and 6 per
cent. of borax, mixed with water.

Improvements in the Preparation of Casein.—(French
patent 396,014: C.A. Baechler.) Mulk, coagulated by means
of rennet or an acid, is agitated in order to prevent the flakes
of curd from agglomerating, and is at the same time treated
with about one part per 1000 of a substance such as alum,
which has a similar effect on the curd, the temperature being
then raised to about 52° C. and stirring continued till the
mass is cold. The resulting granular casein, which may be
separated by a centrifugal machine, is neutral, but may be

40 CASEIN.

rendered alkaline by the addition of sodium bicarbonate, 3-5
per cent. of which (calculated on the dry weight of casein)
will suffice to render the casein soluble in water. Acid casein
may be prepared by treating the washed, neutral casein with
a@ minimum quantity of acid; or an acid may be used to
coagulate the milk.

In the patent granted to C. A. Baechler (English patent
6247, March 20, 1908), the effect of calcium salts in the pre-
cipitation of casein is made use of, skim milk at a temperature
of 30° C. is mixed with a solution of calcium chloride in the
proportion of about 0°5 part of the salt to 1,000 parts of milk,
and then treated with a solution of rennet. As soon as coagula-
tion commences the mass is well stirred to granulate the
casein. One part of ammonia alum is’ next added and the
casein separated and dried. The casein thus produced is in
a finely divided condition, which obviates the necessity of
drying. The casein in its moist state can also be treated
with a suitable acid or alkali to produce acid—or alkali casein.

CHAPTER IV.
COMPOSITION AND PROPERTIES OF CASEIN.

CaAsEIN, the chief and characteristic albuminous substance in
milk, was, on account of its acid properties, long regarded
as an albuminate, and was classed along with the alkali
albuminates obtained by denaturing other albuminous sub-
stances. Hoppe-Seyler, and more particularly Hammarsten,
were the first to demonstrate its separate entity, its composi-
tion varying somewhat according to the animal from which
it is derived.

The casein of cows’ milk contains: Carbon, 52°96;
Hydrogen, 7°04 to 7°53; Nitrogen, 15°60 to 15°91; Oxygen,
22°78 ; Sulphur, 0°758 to 0°82; Phosphorus, 0°8 to 0°847.

A. Burr! has examined a number of samples of casein,
some of them of commercial origin, and others which he had
himself prepared. ‘The average composition of a number of
samples of commercial casein was :—

‘Water . : ; ‘ ; y ’ . 10°38
_ Dry substance ‘ Se cage ‘ F . 89°32
Fat 4 ‘ ‘ : ; ; ; Ree fg
Casein . ‘ ; ost ‘ ; . 19°45
Ash ‘ : P ; : P : 52 OB

For caseins prepared by himself he obtained the following
figures :— |

1“ Milchwist. Zentralbl.,’’ 1910, 6, 385-394; ‘Jour. Soc. Chem. Indt.,’’
1910, 1327.
| (41)

42, CASEIN.

4 Samples of «1s 15'\Samples of Curd,

4 Samples of Acid Rennet Casein *) _ precipitated by Mean.

Casein, (Paracasein). Rennet and Acid,
Water . ; 555-8 65 0°6-2°97 7308-80-03 76°70
Dry substance 91°35-94°45 97 03-99°40 * 19°97-26°92 23°30
Fat : ; 005-075 0°08-0°55 0°36-1°10 0°66
Ash ; ; 0°0 5°0-8°55 1°18-2°18 1°59
Nitrogen content of casein, fat and ash free . 15°58-15°63 —:15°64-15°74
Conversion factor ; A ; ; : . 6°40-6°41 6°35-6°40

The elementary composition of casein is very similar to
that of albumin and fibrin, as shown by the analyses of
Mulder :—

ANALYSES BY MULDER.

Casein. Albumin. ‘Fibrin.
Carbon ‘ . 83°83 53°5 52°7
Hydrogen . é 7°15 70 6°9
Nitrogen . -e Soe 15°5 15:4
Oxygen ; 22°0 23°5
Sulphur. ; \ 23°37 { 1°6 2
Phosphorus . ; J 0°4 0°3

100-00 100°0 100°0

ilmenite.

The following are also eye of casein by varlous
observers :—

Scheerer.
Dumas e By
Dumas. and Jones. Rochleder. Scheerer. By By Acetic
Cahors. Alcohol. Souring. Acid.
Carbon . : 58°7 60°50 55°05 56°24 54665 53°77 54:0 53°8
Hydrogen ‘ 7°2 6°78 7°59 7°97 7°465 7°2 7:2 74
Nitrogen > 166 16°17. 16°89; 15°88: 16°724 163.2 4 157
Oxygen .
Sulphur . +} 99°65 94°55 21°47 19°06. 22°146 28°5 - 23:1 23°11
' Phosphorus :

00°00 100°000 100°0 100°0 100-0

tg eee ae
—————— ————

100°0 100°00 100-00

— —— Sl
———————— OS

—

._ Dumas and Cahors have examined the caseins derived
from the milk of various animals, their results being gven

‘below :—

COMPOSITION AND PROPERTIES OF CASEIN, 43

ANALYSES OF DUMAS AND CAHORS.

Ppt. by posse Acid. ha by Alcohol.
From Fro Fro Fro From
. Cows’ Milk. Goats’ Milk. Asses’ Milk, Sheeps’ Milk, Human Milk.
Carbon . . 83°5 53°6 53°7 53°5 53°5
Hydrogen : yes | y Sa: 71 . Tl 71
Nitrogen <i 40'S 15°8 16°0 15°8 15°8
Oxygen, ete. . 23°6 23°5 93-2 23°6 23°6
100°0° 100°0 100°0 160°0 100-0

These samples were dried at 150°C. The ash varied
between 1°5 and 5:4 per cent.

F. Tangl! has also made analyses of caseins from the
milk of various animals, his results being as follows :—

Milk of—
Cow. Buffalo. Sheep. Goat. Mare. Ass.
Carbon . 52°69 52°88 52°92 52°90 52°36 52°57
Hydrogen . 6°81 7°81 7°05 6°86 7°09 701
Nitrogen . 15°65 15°78 15°71 15°48 16°44 16°28
Oxygen . 28°141 21°925* 22°794 | 23°30 22°705 22°495
Sulphur ‘ 0°832 . 0°833 O°717 0°70 0°528 0:588

Phosphorus . 0°877 0°773 0°809 0°76 0°877 1°057

H. Droop Richmond? found that the average percentage
of nitrogen in casein estimated by the Kjeldahl process and
calculated on the water and ash free basis is 15°65, which
would give a conversion factor for the albuminoid of 6°39.
The results obtained by the Dumas method are somewhat
higher, which he ascribes to be due to the presence of un-
oxidised carbonic oxide in the combustion gases.

It is lacking in glycocoll and the carbohydrate group,
but yields a large proportion of tyrosin and tryptophane.
Accordingly, it is readily decomposed by pepsin and trypsin,
it is also attacked by erepsin, but does not furnish any-
hetero-albumose on peptonisation.

Owing to the ease with which it is decomposed, casein
also plays a special part in metabolism. The proportion of

1“ Pfliiger’s Arch, d. Physiol.,’”’ 1908, 121, 534-549 ; “Jour. Soc, Chem.

Indt.,’’ 1908, 416.
2 Analyst,” 1908, 33, 179-184.

44 _ CASEIN.

lysin and glutaminic acid is particularly high; and according
to Wildenow and Salkowski, paranucleie acid contaminated
with albumin containing 3 to 4 per cent. of phosphorus is also
present. The salts of casein are specially important; and,
though like all albuminoids, it is capable of forming com-
pounds with acids, and is therefore readily soluble in an
excess of acid, its own acid characteristics are demonstrable.
It is therefore amphoteric in its reactions. According to
Lacqueur and Sackur, the equivalent molecular weight of
casein in its compounds with bases is 1,135, and its basicity is
4 to 6. In its acid functions, which are the stronger of the
two, it is stated to behave as a tribasic acid; is also affirmed
that it combines with a fixed amount of caustic soda, 1 gram
uniting with 0°88 millimol. of NaHO to form a solution
having a normal electrical conductivity but incapable of
passing through a parchment membrane. The far higher
molecular weights of 5,000 to 6,000, found by. Salkowski,
Hammarsten, Lehmann, Hempel and Soeldner, are based
partly on hydrolysis and partly on the investigation of the
acid salts. A. W. Bosworth and L. L. Van,Slyke! estimate
the molecular weight of casein at 8,888 and state that it
contains two atoms of phosphorus.. Sdldner differentiates
between two series of salts, Courant three. In milk, casein
is supposed to be present as calcium caseate ; and, according
to Courant, not as the neutral salt, but as calcium dicaseate,
combined with calcium phosphate. This point, however, is
not yet conclusively decided. Revis and Payne also state
that the casein is combined with calcium phosphate, while
Richmond adduces evidence to prove that it is present as a
calcium-sodium salt in combination with one molecule of
calcium phosphate. Certain authorities believe that it exists
as a lactate—calcium lactate—which is hardly probable.

1See also p, 47.

COMPOSITION AND PROPERTIES OF CASEIN. 45

Sdldner'! believes that the calcium in milk is present as
mono- and di-calcium phosphate, which on boiling are con-
verted into the insoluble triphosphate. According to Trunz,”
milk contains approximately 0°18 per cent. of calcium,
about 76 per cent. of this being combined with casein,
the remaining 24 per cent. existing as phosphate and
citrate. He found by experiment, that. of the total cal-
cium present in the original milk 175 to 24 per cent.
was precipitated on boiling, at the same time the
percentage of phosphoric was found to be correspondingly
decreased. Calcium caseate may, per se, possess the property
of maintaining in solution or suspension the neutral calcium
phosphate also present in the milk, or the milk may contain
a true double salt of calcium caseate and calcium phosphate ;
in either case, the calcium phosphate is thrown down when >
casein is precipitated along with the total milk fat, the
emulsification of which is therefore due to calcium caseate.
This again is the reason of the great difficulty experienced
in obtaining casein free from fat and calcium phosphate.
According to Mulder casein contains about 6 per cent. of
calcium phosphate. Whilst free casein is perfectly insoluble
in water, the neutral sodium and ammonium salts are readily
soluble. Even the acid salts of casein are soluble in water,
but the solutions are strongly opalescent. Calcium caseate
dissolves easily, but the solution has a distinctly milk-white
appearance. Nutrose and plasmon are sodium caseate.
Ammonium caseate is known as ‘‘ Eucasein’”’.

Casein is dissolved by solutions of alkalies, alkaline earths,
carbonates, phosphates, borates, and other alkaline salts.
Casein is precipitated from solutions of these salts, and there-
fore also from milk, by very weak mineral acids or by strong
acetic acid, and is redissolved when the precipitating acid is

1« Tandw. Versuchs.,” 1888, 351.
2 Zeits. f. physiol. Chem.,”’ 1903-4, 40, 263.

46 CASEIN.

in excess. Casein adsorbs both acids and alkalies from
solution, that is to say, when added to solutions of these
substances they become more concentrated in the moist
casein than in the unabsorbed liquid. This phenomenon of
adsorption is common to colloidal substances, being due
largely to their great surface energy, the material becoming
condensed or concentrated upon the enormous surface which
they exhibit. Together with this action is also to be noted
the combination of a portion of the acid or alkali with the
casein. Peculiarly both.H and OH ions cause the swelling
of casein at certain concentrations, the OH ions, however,
having much the stronger effect.

According to Tangl! the adsorption of acids by casein is
directly proportional to the acid concentration.

W. Van Dam? determined the amount of lactic acid ad-

sorbed by casein from a a solution at 18° C., using Bredig’s

ethyl diacetate method to determine the H ions left in the
solution, and found that with quantities of casein ranging
from 0°25 to 1 gram, there being an excess of H ions present,
casein combined with a constant quantity of lactic acid which
-amounted to 4:25 per cent. of the casein present. With larger
quantities of casein the proportion of lactic acid was relatively
less. From his experiments he concludes that the molecule
of casein contains four replaceable hydrogen atoms to one
basic group. |

J. H. Long?’ finds that at ordinary temperature com-
bination of acids and casein takes place in the proportion of

1 gram of casein to 7 c.c. of ea hydrochloric acid, hydro-

bromic acid, hydriodic acid, sulphuric acid, or acetic acid,

1 Chem. Zeit.,” 1908, 1, 1288.
2“ Chem. Weekblad,’’ 1910, 7, 1013.
3 Jour. Amer. Chem. Soc.,’’ 1907, 29, 1334-1342.

COMPOSITION AND PROPERTIES OF CASEIN. A7

also appreciable quantities of tartaric, phosphoric, oxalic, and
other acids are similarly fixed. The affinity for bases is
- somewhat greater than this, 1 gram of casein combining

N
with 9 c.c. of 9 solutions of hydroxides or carbonates of

sodium, potassium, lithim, or ammonium. On heating a
larger proportion of acid is fixed owing to the hydrolysis
which then takes place resulting in the formation of de-
composition products which combine with acids. |
: L. L. Van Slyke and D. D. Van Slyke! have carried out
a series of experiments to determine the action of very weak
acids upon casein. The solutions employed by them were
hydrochloric acid, sulphuric acid, lactic acid, and acetic acid
in four different strengths, viz., N/125, N/500, N/1000, and
N/2000. The times of contact varied from five minutes to forty-
eight hours and the temperatures were 0°, 25°, and 45° C.
The effect of neutral salts, ¢.g., potassium chloride and mag-
nesium chloride on the course of the reactions was also studied.
It was found that even after several hours contact at 0° C. little
or no casein dissolved in acids not stronger than N/500, the
same remark applies at 25° C. to solutions not stronger than
N/1000. An increased solubility was, however, noted on
raising the temperature, prolonging the time of contact or
using acid of greater strength. The solvent action of the
acids varied in the following order, hydrochloric, lactic,
sulphuric, acetic, the first named being the strongest. The
rate at which casein dissolves was found not to be directly
due to the H ion concentration or to dissociation since the
organic acids had a greater solvent power than would be
accounted for if such were the case. The amount of acid
taken up by the casein was determined by shaking the latter
with the solution of acid and, after filtering, determining the
loss in electrical conductivity of the solution which gave a

1“ New York Agri. Expt. Stat. Bull.,” No. 3, 1906, 75-162.

48 CASEIN.

measure of the amount of acid taken up. With 1 gram of
casein and 100 c.c. of N/1000 hydrochloric acid, after three
hours contact, 50 per cent. of the acid was taken up. The
amount of acid adsorbed by the casein, however, varies with
the concentration of the acid, the duration of contact, the

temperature, and the nature of the acid. Some acid is ~

removed even from the very weakest solutions, but the
acid is never totally adsorbed even when the proportion of
casein is relatively large. The amount of acid adsorbed
when equilibrium was established varies practically directly —
with the concentration of the acid within the limits of the
experiments (N/125 to N/1000), and the equilibrium ratio
(that is the concentration of acid in 1 gram of casein divided
by the concentration of acid in 1 c.c. of the surrounding
liquid) is for sulphuric acid 675, hydrochloric acid 147, lactic
acid 80, and acetic acid 30. The acid thus taken up is
removed by continued washing with water. No adsorption
of neutral salts, such as potassium chloride and magnesium
sulphate was found to take place from dilute solutions.
These results are in favour of the assumption that the
reaction between casein and acids is an adsorption phenom-
enon, and the authors are of opinion that the souring of milk
is due to the precipitation of free casein eapned lactic acid
held by adsorption.

In experiments on the titration of casein using different .
indicators it was found that the sodium salt readily hydrolyses.
and becomes alkaline so that it was impossible by this means
to determine the molecular weight of casein. The acid
character of casein being so very slight, it was also necessary
to have a large excess of casein present in order to obtain
an acid reaction with less sensitive indicators than phenol
phthalein. Precipitation of casein or its salts ensues when
the solution is saturated with common salt, magnesium sul-
phate or sodium sulphate. For the bulk of the casein the

COMPOSITION AND PROPERTIES OF CASEIN. 49

limits in the case of ammonium sulphate are 2°2 and 3:6,
though a slight cloudiness is already observed when 1°2 is
reached. In other respects casein behaves in acid, neutral
or alkaline solution like the other albuminoids, 7.¢., is pre-
cipitated by salts of the heavy metals CuSO,, ZnSO,, etc.,
and certain complex organic acids, so-called alkaloid reagents,
when the acid is in excess also by tannin, metaphosphoric
acid, and phosphotungstic acid. In addition, casein is thrown
down by most acid aniline dye-stuffs and a few complex
organic acids, but only when the reaction is decidedly acid.

Potassium alum, in suitable concentration, will throw
down the casein in milk, without affecting the other albu-
minoids present. With an excess of the salt, however, the
precipitate is redissolved. Other important compounds of
casein are those formed when milk is coagulated by rennet,
whereby the casein is transformed into paracasein. Like the
unaltered casein, this substance is readily soluble in alkalies,
though its calcium salt is insoluble; hence, when a soluble
calcium salt is present in the liquid, insoluble calcium
paracaseate or cheese is formed. The coagulation of milk
proceeds in two stages, occurring successively, the actual
enzymic conversion of the casein by the rennet ferment,
and the visible coagulation for which alone the presence of
lime is necessary. Paracasein is not precipitated when the
soluble calcium salts of the milk have been removed by
oxalic acid. Halliburton would confine the name para-
casein to the coagulated casein, calling the soluble casein
‘caseinogen ”’.

According to J. Mellanby,' caseinogen is obtained by
mixing separated milk with three times its volume of
alcohol and cooling to 15° C., The precipitate which forms
is separated by filtration, digested with ether till free from
fat, and then dried in the air at ordinary temperature. This

1« Biochem. Jour.,” 1915, 342; ‘ Jour. Soc. Chem. Indt.,” 1915, 1108.
. 4

50 CASEIN, °

material is a complex containing protein and calcium phos-
phate in the proportion of approximately 1 gramme mole-
cule of calcium phosphate in 3,500 grammes of the material,
which would suggest that one unit of protein weighing 3,400
grammes is combined with one molecule of calcium phos-
phate, the author expressing the formula as |

CaXR . (NH.),C,H.(PO,)s.

The group X having feeble acidic functions.

From a solution of caseinogen, six molecules of acetic —
acid precipitate acidic caseinogen or casein, of which 3,400
grammes contain 1 gramme atom of phosphorus.

Li. Piet states that paracasein differs from casein by con-

taining a higher amount of calcium and phosphorus, and
after precipitation a greater amount of nitrogen and a smaller
proportion of calcium are left in the milk serum or whey.
Paracasein is also less soluble in a suspension of carbonate
of lime in water, and is precipitated from its solution in lime
water by phosphoric acid. According to the author casein
contains 1°315 per cent. of phosphorus. In rennet casein
he found 2°16 per cent. of calcium, and in acid casein 0°63
per cent.
In its other properties paracasein is identical with casein,
but is thrown down more readily than the latter by common
salt, so that it can be made to coagulate, by means of large
quantities of salt without any addition of lime.

No real coagulation occurs when casein is exposed to
high temperatures; and the solutions of its salts may be
boiled without suffering any alteration. In the dry state,
on the other hand, according to Lacqueur and Sackur, it
becomes partly insoluble when heated to 94° to 100° C.;
whereas, according to the earlier report by Hammarsten,
‘this does not ensue below 120° to 130° C. Halliburton
noticed a change when casein suspended in water was heated

COMPOSITION AND PROPERTIES OF CASEIN. 51
ab
to 75° C, What happens to thei casein when milk is boiled

still remains unknown.

According to Richter, casein is precipitated from its soi:
tions by sodium chloride, ammonium sulphate or magnesium
sulphate without change, leaving albumin and nuclein in
solution. Pure 2 per cent. solutions of casein and para-
casein are, however, not salted out by a saturated solution
of common salt according to §. Schmidt-Nielson.’ On the
addition of 0°4 per cent. of calcium and 0°05 per cent. of
magnesium in the form of salts the casein is precipitated in
the form of an alkaline-earth caseinate. For the complete
precipitation casein requires 6°5 per cent. and paracasein
about 3 per cent. of their weights of calcium respectively.
Barium and mercury ions behave similarly, but are not so
effective, being only about one-third as strong in their action.
Mineral acids in excess precipitate casein solutions. The
solutions of the alkali and calcium salts of casein do not
coagulate on heating. A lime-free solution of casein is not
coagulable by rennet, though it becomes so when a calcium
salt is added, even though in the meantime the rennet has
been rendered inactive by boiling.

After Hammarsten had investigated this action of cal-
cium salts on the curdling of milk by rennet, 8S. Loevenhart
demonstrated that a similar effect 1s produced by the salts
of lithium, beryllium, magnesium, strontium and barium, as
also by the proto-salts of iron, cobalt, nickel, and manganese.

Purified casein is a snow-white, perfectly ashless powder.
A solution of casein shows a specific rotation of — 87° or in |
strong solution —- 9t°. The heat of combustion of 1 gramme
of casein is 5°858 cal. It strongly reddens blue litmus paper,
but is only soluble to the extent of a trace in water, though
soluble in alkalies and in water containing calcium carbonate.

1« Bietr. z. chem, Physiol. u. Pathol.,” 1907, 9, 311-321; “Jour. Soc.
Chem. Indt.,” 1907, 709. .

52, : CASEIN.

It also dissolves in a 1 per cent. solution of sodium fluoride,
and in ammonium oxalate or potassium oxalate. From
solutions it is precipitated by acids and by rennet. In the
presence of salts (sodium chloride, and especially sodium
acetate) the precipitation by acids is incomplete. When
purified milk casein is boiled for five hours with 3 parts
of hydrochloric acid (specific gravity 1:19), tyrosin, leucin,
leucinide, C;H;NO, a little aspartic acid and glutamic acid
are formed.

Schutzenberger found that on heating casein with baryta
water in a sealed tube to 150° C. it is split up into the
elements of urea (CO, and NH;), traces of sulphurous acid,
sulphuretted hydrogen, oxalic and acetic acids, tyrosine, the
amido-acids of the series C,H, ,,NO,, corresponding to the
fatty acids C,H»,02, from amido-oenanthylic acid to amido-
propionic, acid, leucine, butylamine C,H,,NO,, and amido-
propionic acid C,H,NO, together with several other products
either not well known or unidentified. Aberhalden has
also determined quantitatively the products obtained by the
hydrolysis of casein, but, as pointed out by J. B. Osborne
and H. H. Guest,! the last aamed author was able to identify
and determine only about 50 per cent. of these. They there-
fore undertook a re-examination of the question with the
result that 67°85 per cent. was accounted for as follows:
Glutamic acid 15°55, leucine 9°35, valine 7:2, proline 6°7,
lysine 5°95, tyrosine 4°5, arginine 3°81, phenylalanine 3:2,
histidine 2°5, tryptophane 1:5, aspartic acid 1°39, diamido-
trihydroxydodecanic acid 0°75, serine 0°5, oxyproline 0°23,
ammonia 1°61, phosphorus 0°85, sulphur 0:76. The residue,
containing substances which could not be identified had a
mean nitrogen content of 13°1 per cent.

In the treatment of casein for the preparation of water-
proof coverings (paints, varnishes, etc.), and particularly of

| 1« Jour, Biol. Chem.,” 1911, 9, 338-353.

COMPOSITION AND PROPERTIES OF CASEIN. 53

plastic masses intended as substitutes for celluloid, or for
other purposes, an important part is played by substances
which precipitate the casein in an insoluble form from its
solutions. Though this may preferably be done by heating
solutions or mixtures of casein along with lime or milk of
lime, still heat is not applicable in all cases. Such precipita-
tion can be effected at the ordinary temperature by treating
the casein solution or mixture with metallic salts, especially
those of copper (cupric sulphate), or with certain organic
substances, e.g., alkaline solutions of shellac, the addition of
which immediately separates the water contained in the
mass. A patent for the production of insoluble casein was
taken out in America by Dunham, according to which 15
parts of borax and 85 of commercial casein are dissolved in
400 parts of water, the solution being then treated with 15
parts of hexamethylene tetramine (produced by the action of
ammonia on formaldehyde) and afterwards evaporated, the
dried product being exposed to warmth and moisture. In
this form casein is a suitable peri for albumen for
certain purposes.

A far more important matter we the casein industry is the
German patent 99,509, or rather the addition to that patent,
according to which casein, albumoses, and the liquid con-
version products of glue and gelatine are rendered insoluble
by formaldehyde. The insoluble products thus obtained can
and do find technical application in the form of layers or
coatings, as detailed below. :

For certain purp ses in chromo-lithography it is necessary
to provide paper with a perfectly smooth, absorbent and yet
resistant surface. ‘This object is now accomplished by coating
the paper with size or casein hardened with formaldehyde, a
simple operation which has become of great importance in
the paper industry as well as in chromo-lithography.

Sinilar fine, insoluble layers of casein can also be prepared

54 CASEIN.

without a paper backing, and are then specially adapted for
supporting sensitised emulsions in photography (photographic
films). In this case they supersede the celluloid hitherto
used, being free from its objectionable qualities, inflammability

~and so forth. ]

Coatings of casein may also be applied to wall paper,
improving its durability and making it washable.

It is, however, neither essential nor desirable that this
coating should be applied when the paper is being made,
since the continuity of the coating would, in that case, suffer
when the paper was being cut and hung. It is therefore
preferable to apply the coating when the paper is on the
walls ; and experience has shown that this can be done with
ease and perfect success.

A solution of casein and formaldehyde is also suitable as
a coating for smooth brickwork, in all cases where a water-
proof and washable coating is desired. The varnish paints
and enamel paints now used for this purpose are more
troublesome, dearer, and have the great drawback of con-
tinuing to smell for a long time. On the other hand, casein
varnish is cheap, easily applied, loses all smell in a few hours,
and also forms an excellent disinfectant. This is certainly a
valuable property for hospitals, barracks, dormitories, rooms,
etc. i
The insoluble compound of casein and formaldehyde can
also be obtained in large blocks; and by means of a patent
process, owned by the Vereinigte Gummiwaaren Fabriken
Harburg-Wien (formerly Menier & Reithoffer), it 1s prepared
in solid, horny plates and bars, forming a perfect substitute
for ivory, ebony, horn, tortoiseshell, celluloid, coral, ete.
The inventor has appiied the name ‘“‘galalith” to this
product.

The properties of galalith are such as to ensure for it a
great future. It is inodorous and uninflammable, thus pos-

COMPOSITION AND PROPERTIES OF CASEIN. 55

sessing, as already mentioned, a great advantage over celluloid.
It can be dyed, and the crude article can be bent, blocked,
and stamped while warm, retaining its form perfectly when
cooled. It does not attack metals, and is one of the best
insulating materials known for electrical purposes. These
qualities are sufficient to secure for galalith a very extensive
sphere of application, certain to react favourably on the milk
industry.

Already this material is used for manufacturing a large
number of articles, such as plates, combs, cigar-holders, house-
hold fittings, etc.; and it is also possible to utilise galalith
for accomplishing new technical results.

When a solution of casein is treated with formaldehyde
and poured on to glass plates it furnishes transparent films,
which are insoluble in water. Spitteler and Krische found
that the addition of formaldehyde to casein solutions gave, on
subsequent precipitation, products that swelled up in water
and had a fracture like cartilage. On the other hand, they
discovered that this drawback could be remedied by treating
the casein with formaldehyde after precipitation by acids or
lead acetate, preferably after the precipitate had been freed
from water, as far as possible, by evaporation or pressure, the
hardening with formaldehyde being then undertaken. This
treatment yields products with the properties of horn. In
their patent specification the inventors give a comparative
table of the behaviour of buffalo horn and of casein products
prepared in various ways, showing that while buffalo horn
absorbs 153 to 18 per cent. of water, when submerged in that
liquid for thirty-three days, the new product hardened with
formaldehyde takes up 16 to 23 per cent. of water, behaving,
therefore, in a very similar manner. |

The estimation of casein is performed by precipitating
the milk by saturation with magnesium sulphate, the nitrogen
in the precipitate being determined, and the casein calculated

56 CASEIN.

. from the result. The filtrate from the casein precipitate is
diluted, and the lactalbumen thrown down with tannic acid
or phospho-tungstic acid, the nitrogen in this precipitate
being also estimated.

Analysis of Industrial Casein.—A good inittistrial casein
should be properly and carefully prepared by souring fresh
milk and washing and drying the curd so that no extraneous
solids are present. The odour should be fresh, and not
mouldy or rancid. On being treated with ammonia and left
to stand for several hours, the sample should not leave any
undissolved sediment, but should furnish a clear syrupy solu-
tion. Moisture content.—5 grammes of the sample are
weighed into a nickel capsule and dried at 100° to 105° C.
until of constant weight. Overheating causes error due to
oxidation. Fat content.-—-A weighed quantity of the sample is
extracted with alcohol and ether in a Soxhlet ‘apparatus,
the solvent being then expelled and the extract weighed.
Ash.—2 to 3 grammes of the finely powdered sample are
weighed into a quartz capsule, carefully incinerated and
washed with water, the residue being moistened with am-
monium nitrate, calcined at white heat, the solution in water
added, evaporated and dried at 100° C., and weighed.
Acid casein is harder to incinerate than that made with
rennet, and contains less ash, the maximum being 6 per
cent. as compared with up to 8} per cent. Free acid.—
10 grammes of casein are shaken up with 100 c.c. of water
and filtered, 60 cc. of the filtrate being treated with a
few drops of phenolphthalein and titrated with decinormal
potash until tinged with red. _Well-made casein should only
contain a very small amount of acid, especially when it has
been in store for some time. The test is best applied in
comparison with a sample of known purity. Solubility.—
This is a particularly important determination, since it enables
the presence of accidental or intentional additions of sand

COMPOSITION AND PROPERTIES OF CASEIN. BF

to be detected, and old casein to be distinguished from fresh.
The test is performed by weighing 10 grammes of air-dry
substance into a test glass and leaving it in contact with
50 c.c. of water and 1 to 2 of 33 per cent. ammonia for several
hours, heating to 60° C. if the casein does not dissolve with-
out. If pure, the substance will swell up and furnish a trans-
parent, syrupy solution. Casein which has been stored for a
long time or dried at too high a temperature gives a cloudy
solution. Sand and other impurities are deposited as sedi-
ment. 'T’o ascertain their percentage, 1 gramme of the sample
is dissolved in 25 c.c. of water and 10 drops of ammonia, the
sediment being decanted, boiled with hydrochloric acid to
separate the sand from organic impurities, starch, etc., and
collected on a weighed filter, incinerated, and weighed.
Organic impurities are detected by the microscope. The
solubility in borax is tested by adding powdered borax to the
casein mixed with water, and noting the amount needed to
effect complete solution.—‘‘ Rev. Prod. Chim.”

CHAPTER V.
CASEIN PAINTS,

THouGH it has long been known that casein combines with
certain substances to form agglutinant compounds, which
become more or less insoluble on exposure to the air, and
though it has been stated that casein has been detected in
old paintings, nevertheless it is only within the past forty to
fifty years that any extensive use has been made of it for
this purpose. That an addition of milk to lime-washes
greatly increases their durability has also long been known;
and, in fact, such a mixture constituted the first casein paint,
the caesin of the milk forming with the caustic lime a com-
pound which is the basis of all such paints. The casein is
rendered soluble, a result that can be produced, not merely
with quicklime, but also with various substances having an
alkaline reaction. The chief casein paints we shall here con-
sider are those met with in commerce in the paste or liquid
form, containing the casein in a disseminated condition, and
in some cases already mixed with other substances used in
paint, such as linseed oil, boiled oil, resins, or petroleum, in
- order to produce special effects. Others again—and of late
these have become the more important—are supplied by the
makers in the form of powder, and contain casein and alkali
in the dry state. It is only when these paints are mixed
with water, to render them fluid for use, that the alkali is
dissolved, and, in turn, acts as a solvent for the casein.

The coatings furnished by the different kinds of casein
(58)

CASEIN PAINTS. 59

paint dry with a matt surface, 7.e., without gloss, like all
water-colour paints, and therefore exhibit a property which
is difficult to impart to oil paints without impairing their
durability. Under the influence of the air, the paint also
acquires a certain firmness, and does not rub off like lime-
washes. It is fairly durable when exposed to the air, but
when placed in situations where it is exposed to wet or heavy
rains, 2.¢., on the weather side of a building, it suffers more
quickly than oil paints. On the other hand, all casein paints
have the advantage of drying quickly and being easy to work,
without requiring any special preparation of the surface to be
painted, drying without gloss, on brickwork, plaster, wood,
canvas, etc., and without stopping the pores of brickwork.
These paints are soaked in cold water in order to dissolve
the soluble binding constituents, salts and similar compounds,
so that they may dissolve the casein completely when diluted

further with water, and also perform their chemical functions.
In addition to the binding constituents the paint powders of
this kind contain mineral matters (whiting, china-clay, clay,
caustic lime, etc.), which form the bulk of the mass and give
covering power, whilst body colours are also present to pro-
duce the desired tint. The pigments, which are added in
merely minute proportion in the case of pale tints, must be
perfectly unaltered by lime and alkalies. Consequently, a
green, for instance, compounded of Prussian blue and chrome
yellow, could not be used; the pigments used must be as
pure as possible.

The media of these cold-water paints, and on which their
quality and utility chiefly depend, are mostly albuminous
substances of vegetable or animal origin, generally casein,
dissolved by means of alkalies and afterwards rendered in-
soluble by the action of air on the coat of paint, as already
stated. Excellent paints are also made from blood albumen
and similar substances; but in some cases, glue, mucilage,

60 CASEIN.

dextrin, glutin, or starch, in admixture with certain salts, are
also employed, insoluble compounds being thereby formed.

The paints with a basis of casein have proved to be the
_ best, and are most extensively used. They are made from
- commercial casein powder, which readily dissolves in suit-
able proportions of caustic lime, ammonia, or alkaline salts.
When blood or blood albumen is used, the one must first be
well dried and the other finely ground, in order that they
may form a good bind with caustic lime. Glue also must be
ground, and the mass may be treated with potassium bichro-
mate, tannin, alum, etc., to render it insoluble. Glutin must
be allowed to ferment, and then be dried, ground and mixed
with a certain proportion of alkali for use.

In preparing all these powdered paints, which are to be
made up into a wash with cold or hot water or milk of lime,
the main point is to adjust the proportions of casein, starch,
glue, glutin, or other albuminoids so as to properly fix the
pigment used for covering purposes and also for producing
the tints. An insufficient quantity of the medium would
lower the durability of the paint below the useful limit, so that
it would not stand the action of rain, snow, etc., and would
wipe off with the hand, or a brush. |

On the other hand, an excess of medium would make the
paint streaky and hable to crack and peel off. Since the
loading materials used require very different quantities of
binding constituents to fix them properly, this circumstance
must be borne in mind. ‘The same applies to the body
colours, which require a larger or smaller quantity of bind-
ing ingredients, according to whether they are specifically
heavier or lighter. These pigments should be able to retain

their colour when used in mixtures containing caustic lime
alkalies, or substances with an alkaline reaction. Intimate
admixture of the various ingredients is an important factor
in these paint powders. The percentage of medium in the

CASEIN PAINTS. 61

mixtures is relatively small, and yet it must be distributed
in a perfectly uniform manner throughout the mass; other-
wise, if one portion of the paint contained too much, and
another too little, the result would be noticeable in the un-
even character of the coat of paint after application. Careful
mixing is therefore an essential feature. a
To secure this result, the medium and pigments. are

Fic. 12.—Gardner’s ‘‘ Rapid” Sifter and Mixer.

placed in a sifting mill of the type shown in Fig. 12, made
by Wm. Gardner & Sons, Gloucester. This consists of a
mixing chamber surmounted by a hopper and a chamber,
containing a spiral roller brush fitted and working exactly
in a semi-cylindrical sieve. The materials are fed in at the
top, and are carried round by the brush, all soft lumps being
broken up until they pass through the sieve along with the
fine powder. On the other hand, all the hard lumps and

62 CASEIN.

waste matters are discharged through an opening at the end
of the machine. From 1 to 30 cwt. per hour can be sifted
and mixed in this way, according to the size of the machine.
Or after the ingredients have been carefully sifted they
are put through a mixer of the Werner and Pfleiderer ‘“‘ Uni-
versal” type (Fig. 13). As, in these cold-water paints,
powders of different densities have to be mixed together, the
machine should be fitted with a two-speed gear—fast and
slow. ‘The fast speed acts as a sort of disintegrator, break-

Fig. 13.—‘* Universal’? Two-speed Mixer.

ing up lumps and large granules thereby ensuring a more
thorough admixture of the ingredients. Consequently, with
a machine of this kind, the preliminary sifting may some-
times be omrtted.

The product obtained by this process of fine sifting and
intimate mixing will satisfy all requirements.

‘** MARBLE LIME” COLOUR FOR OUTSIDE WORK. \

The following ingredients are passed through a colour
sifting and mixing machine :—

CASEIN PAINTS. 63

Casein, soluble in alkali ‘ : 100 parts by weight.

Caustic lime from marble. j 100 ey i
Levigated chalk (whiting) . p 800 Hi +4
Borax . : 3 ; 2 : 1 part ee
Ultramarine (for white only) : 2 to 24 parts ea

It is extremely important that the materials should all
be very finely powdered. The caustic lime, Ca(OH),, is
obtained as a fine white powder by slaking lumps of pure
calcined marble lime with one-third their own weight of
-water in a porcelain vessel. The water and lime combine to
form calcium hydrate, with liberation of heat and a faint
alkaline smell. The resulting slaked lime should be kept in
tightly closed vessels or, preferably, used immediately.

With regard to making this preparation in different
‘colours, it should be noted that the mixing of the earthy
pigments or so-called lime-proof colours may take place
either when the paint is being made or else just before use
(see instructions later). The following pigments are fast to
lime: Antimony yellow, barium yellow, barium white, ivory
black, chrome green (true), chrome orange, colcothar, green
earth, cadmium yellow, cobalt blue, cobalt green, Mars
brown, Naples yellow, ochre, Paris black, satinober, Schwein-
furt green, Terra di Siena, ultramarine, umber, Vandyke
brown, and zinc white. If the pigments are added at the
time of manufacture, the weight of levigated chalk must be
reduced in proportion to the amount of pigment used. For
instance :—

Casein, soluble in alkali ‘ P é ‘ ; 10 parts.

Caustic lime 5 ; é P ; ; : HP 33
Levigated chalk . ‘ ; ; j . P 40... 5,
Ochre . ; : ; ’ ; ; ‘ 40° 5;

Borax as before ; se usne nil,
When, by making a little of the mass up into paint, the

ingredients have been found to be thoroughly mixed, the
powder must be packed in tightly closed boxes, lined with

64 CASEIN.

paper. In this way the article will keep indefinitely, in a
dry place, without losing any of its properties.

The making of this powder up into paint is a com-
paratively easy matter, though a certain amount of care is
necessary to ensure good results. The operation may be
performed in any vessel that is clean and free from grease,
in the following manner: 50 parts of water are added by
degrees to 100 parts of the powder, with constant stirring,
which is continued until the mass is homogeneous and free
from lumps. The mass is then covered with a thin layer of
water and left for about three-quarters of an hour, after
which it is again stirred, and more and more water is added
until a workable paint is obtained, of about the same con-
sistency as oil paint. When intended for coating rough.
surfaces the paint should be a little thinner, but may be
thicker when used to replace oil paint for smooth surfaces.
It should be used without delay, as it is liable to set hard in
a comparatively short time, becoming unfit for use in about
twelve hours.

Hence it is not advisable to make up any more of the
paint than can be used the same day. If, after the paint
has remained some time in the vessel, it skins over, this
skin must be removed before again using. Made-up white
paint of this kind can be afterwards coloured by mixing up
the pigments with water to a semi-fluid mass, and stirring
this into the paint until uniformly incorporated therewith.
In this case also it is desirable to try a little of the paint
before using it on the work in hand. La:

The application of the paint and the preparation of the
surface are carried out in the same way as mentioned in the
chapter on casein painting. A solid and clean surface is
essential to success. As the paint will adhere to any solid
surface, such as lime, plaster of Paris, or cement, plaster,
brick, metal, stone, or wood, as well as canvas without any

CASEIN PAINTS. 65

preparation, all that is necessary is to clean the surface of
dust and dirt. Painting can then be begun at once. The.
- paint is laid on with a clean, but somewhat worn brush, free
from grease, the paint working better than with a new brush.
It is laid on fairly thick and spread by working the brush
about, this method ensuring a better hold on the substratum
and giving a more uniform coating free from spottiness. In
other respects the operation is much the same as when oil
paint is used; and the paint itself is stirred in the can at
frequent intervals.

The paint dries very quickly, as smooth as enamel, and
. in thirty-six to forty-eight hours can be washed and will
stand the weather. On account of its elasticity it can be
varnished, painted or stencilled on. If applied to a firm
substratum, it will neither crack nor peel off ; but the surface
must be freed from old coatings of lime-wash or distemper
before the casein paint is laid on. In the case of oil paint
that is still intact, this precaution is not necessary.

If it is desired to have a glossy paint for indoor use, the
painted surface is sprayed over with a liquid mixture of wax
and turpentine, which is afterwards polished.

Notwithstanding their power of standing weather, cold-
water paints are porous and do not prevent the circulation
of air. On account of their good qualities, these paints are |
in frequent use both for outdoor use and for interior work, in
dwelling-houses, factories, hospitals, etc., as also for coating
wood, iron, cement, etc.

Casein Paint according to an Older Method.—The curd
of sour milk is boiled for about a quarter of an hour in an
enamelled or glazed vessel and then transferred to a sieve,
where it’ is washed with cold, hard water until perfectly free
from acidity, after which it is wrapped in a cloth and pressed
until only a little moisture is left. In this condition it is
mixed with one-fourth of its weight of burnt lime, previously

66 CASEIN.

slaked with a threefold weight of water, the colouring
matter, mixed or ground with oil or water, being next added.
The resulting paint may be applied to stone, gypsum, or zinc,
but if intended for use on wood it should be first mixed with
10 per cent. of linseed oil. If too thick, the paint can be
thinned with oil or water.

SUNDRY RECIPES FOR CASEIN PAINT.

Casein . . ; : , ; . 144 parts by weight.
Slaked lime . : : ; : ; 7 ‘
Spanish white. ; : . . 280 *
Earth pigment . ; ; : ° 2 >
Water , i : ; ; . 160 *

Another proved recipe is :—

Skim milk : ; : , ‘ 4 ; . #$ gall.
Freshly slaked lime . ; z , ; é - 602.
Linseed oil or-poppy oil . ; , ‘ ‘ {isthe
Spanish white . é : ; 5 : : . 82 1b,

The analysis of a casein paint for coarse work showed it
to have the following composition: Dry residue, 51°6 per
cent.; water, 48'4 per cent.; ash in residue, 29°7 per cent. ;
nitrogen, 0°537 per cent.; (= to casein, 3°36 per cent.). The
ash consisted of 24°6 per cent. of calcium oxide, 31 per cent. of
silica, and 2°0 per cent. of ferric oxide. The silica was derived
from the earthy pigment used. This paint can be imitated
by slaking 30 parts of quicklime with 70 parts of water,
allowing the product to cool, and then stirring into it 20 parts
of white curd obtained from separated milk. A suitable
amount of pigment is added to the mixture.

In the manufacture of liquid casein paints it is essential
for good work to have the materials thoroughly ground
together, for which purpose the dry pigments should be
mixed with a portion of the casein solution sufficient to
make it into a thick cream. This liquid is then passed
through a cone-paint mill of the type shown at Fig. 14, by

CASEIN PAINTS. 67

Messrs. Follows & Bate, Ltd. The material, after passing
through such a mill, will be found to have become much
stiffer in consistency and finer in texture. It will also be
found that on diluting with more of the liquid the pigment
will remain suspended for a much longer time than before
the grinding.

Casein Enamel Paint.—To prepare casein enamel paint,

Fia. 14.—Cone Paint Mill. Follows & Bate, Ltd.

soda casein is intimately mixed with enamel colours—
namely, glass fluxes coloured with metallic oxides (like the
preparations used in porcelain painting), the whole being
ground in water. The product on drying has not the dull
surface of the ordinary casein paints, but shows a gloss more
nearly resembling that of oil paint.

Casein Fagade Paint.—This is a new type of ready-made
casein paint, the chief peculiarity of which is that it must be

68 GASEIN.

protected from contact with carbonic acid gas before use, and
therefore needs to be packed in airtight tins. These paints
can be made in a variety of colours, and in the form of a
thick cream, which is diluted with water for use. They are
prepared by intimately mixing 200 parts by weight of casein
in a pulverising machine with 40 parts by weight of
powdered and sifted slaked lime, the whole being stirred to
a thick fluid with a body colour that has been mixed with
water. Finally, the paint is put autpaee a paint mill and
packed in airtight tins.
The most suitable pigments for this purpose are :—

For White.—Zinc-white, lithopone, blanc fixe, barytes.
Yellow.—Ochre, Indian yellow, Naples yellow.

5, Brown.—Umber.

Black.—Ivory black, vine black, lampblack.

, Red.—Red lead, colcothar, Indian red, madder red.

» Blwe.—Ultramarine, cobalt blue, smalt.

»» Green.—Green earth, cobalt green, chromic oxide green, etc.

Cold-water Paint 1n Powder Form.—In making this class
of paint the proportions must be adjusted in such a manner
that the mixture shall contain 80 parts of dry casein to every
24 parts of dry slaked lime (or caustic soda or potash).
Useful results can be obtained from the following recipes :—

Powdered casein . ‘ : ; > ; 45 parts by weight.
me slaked lime . s j ; ‘ 20 ”

Kaolin . 4 ‘ . : ; 150 ee

Levigated chalk bovhidiisan breeds ‘ 300 Pe

Pigment, according to the colour desired . 5 to 20 a?

For a stone-coloured paint, the following proportions are
suitable :— .

Above paint mass 4 ‘ 3 . . 100 parts.
Light or dark French an : 3 : ; 3 a
Chrome yellow . ; ‘ 3 . : , 2 ea

Cassel brown ‘ : P i . ; , Lbs

CASEIN PAINTS. 69

or any of the pigments mentioned below, together or separ-
ately, may be used :—

Colcothar ; : ‘ - j : . 14 parts.
Vine black. : : » d 2 be Ass
Graphite : ; 6 ; Z F ; arg ie
Chrome green (limeproof) la lgee
Stone green . ; : ; , ‘ ? git ‘a
Ultramarine . > Sage

Casein-lime Colours.—Casein is an important material for
tempera painting, and the use of casein-lime colours for
ordinary painting has been long known. In consequence of
the high price of linseed oil, casein-lime colours are being
much more generally employed, and great pains have been
taken in improving this material to fit it for use as a sub-
stitute for ordinary oil colours. If this object has not yet
been fully realised, none the less, casein-lime colours are now
well established, and are being much more frequently used
as better methods of application are discovered. It is very
important in dealing with any kind of paint, to know exactly
how it should be applied. When casein-lime colours were
first put upon the market much disappointment was caused
by unsuitable methods of application, which resulted in a
strong prejudice against them.

These colours cannot be recommended for every purpose,
and certainly not as a substitute for oil colours. However, if
prepared from suitable raw materials and applied in a proper
manner, they are perfectly satisfactory for certain classes
of work. The successful use of these colours depends upon
the formation ofa casein-lime compound produced by the
two components, casein and slaked lime, in the presence of
water. The casein-lime binds the other mediums together.
It is, of course, necessary to choose materials which are not
easily affected by physical: influences, and especially by
atmospheric conditions.

70 : CASEIN.

Tempera colour contains about 85 per cent. of finest
prepared chalk, with about 10 per cent. of casein and
5 per cent. of calcium hydroxide. Casein used for tempera
colours should always be of the finest quality, pure white in
appearance, the finest powder, and quite free from any
suspicion of decomposition. Inferior brands sometimes con-
tain decomposition products formed by over-drying the
casein. These are not fit for tempera colours, notwith-
standing their low price. They do not possess sufficient
binding power, and very often the decomposition of the
matter referred to causes streaks of yellowish colour on the
painted surface. These substances also sometimes contain
soluble salts which are dissolved more or less by rain, result-
ing in bad colours in outside work.

The properties of the calcium hydroxide used for tempera
colours are also important. It should always be in the form
of very fine powder, and, if possible, be freshly made; in no
case can it be kept in stock for any considerable period of
time, as it takes up carbonic acid from the air. - The calcium
hydroxide should therefore be prepared on the spot. Freshly
burned white lime entirely free from iron, if possible, should
be treated with exactly the quantity of water which it will
take up; an excess of water must be avoided, and great care
must be taken to prevent the formation of lumps; the fine
powder thus obtained should be machine-sifted and then
stored in airtight drums or casks. The lime should not be
slaked with water in the open air, but the operation should
be carried out in drums; a very fine powdered calcium
hydroxide is thus obtained, which can be passed on to the
sifting machines in enclosed trucks. |

It is highly important that the chalk fdr casein-lime
colours should be perfectly dry; if it contains any trace of
water this causes lumps in the product, owing to the im-
perfect formation of the casein-lime compound, and these

CASEIN PAINTS. 71

lumps are not broken up when the colour is mixed with
water. On account of the price, a good natural chalk must
be chosen, the covering power of which must be thoroughly
tested. Sometimes the natural product, although sufficiently
white, is of a crystalline structure, and, therefore, poor in
covering power. This could be remedied by an admixture
with a certain amount of artificially precipitated carbonate of
calcium. Artificial chalk is quite amorphous, and therefore
has a better binding and covering power than the natural
product; the price of tempera colour permits its use in
moderate quantities. Sometimes the superior kinds of china
clay are mixed with chalk to be used for casein-lime colours.
An excess of china clay must not be used if a good article is
required; the use of china clay, it is believed, causes the
colour to crack more readily under the influence of the atmos-
phere. The pure white casein-lime colour can be obtained
only by using chalk alone. A yellowish tint is sometimes
caused by the presence of minute quantities of iron in the
chalk or hydroxide of lime. This can be remedied by adding
ultramarine. If other shades are required, the chalk is mixed
with certain quantities of earth colours fast to lime. Heavy
pigments such as white lead, and, of course, all pigments
which are not fast to lime, must be avoided. Good earth
colours, such as ochre (hydrated oxide of iron), are most suit-
able, and can be used in considerable proportion, up to 30
per cent. or more.

The pigments must, of course, be mixed in a perfectly dry
state. If the casein-lime colour is required for interior work,
‘ pigments only can be employed. Sometimes boric acid or
other antiseptics are mixed with the colour for sanitary pur-
poses, 1 per cent. being the usual proportion. It has been
found best to mix the casein with the chalk and the pigment
colours first, and then to add the hydroxide of lime. This
method retards the action of the two vehicles. The colours

72 CASEIN.

when ready are stored and despatched in airproof receptacles
to prevent any binding of the lime and casein. Casein-lime
colours do not hold well on wood or metal; the coat very
soon shows a tendency to become detached from the ground,
as iron and wood are readily influenced by temperature ;
on the other hand; these colours are very suitable for stone
surfaces and especially for freshly prepared cement walls.
The surface to be painted and the painting material being
of the same chemical nature, the result of the cohesion is
very good. 3

Casein-lime colours cannot be recommended for painting
over surfaces already covered with old lime or oil paint.
Thorough examination of the surface to be painted should be
made before casein-lime colours are applied. The colour
should first be mixed with a little water, equal to about half
the weight of the dry colour; the pulp thus obtained should
be allowed to stand for a quarter or half an hour, and then
about twenty or twenty-five parts more of water should be
added and stirred in. The painting material is then ready
for use. If a glossy coat is desired, only about ten parts of
water are used in the second application; the ready-made
pulp is then thick and more like an oil colour in appearance.
If well made from suitable materials and carefully applied,
casein-lime colours give excellent results and are found to
be thoroughly satisfactory. The success of the casein-lime
colour depends on its suitable application, and rests upon a
thorough knowledge of the character of the paint in question
and its behaviour with the surface to be painted.

Kistory’s Recipe for Casein Paint and Varnish.—Pro-
fessor Modets Kistory, of Moscow, recommends for casein
varnish a mixture of 32 parts of sifted curd and 32 of water,
stirred together at 64° F., the pulp being forced through a
metal sieve in order to secure the subdivision of the particles
and their more intimate admixture. Meanwhile, some freshly

CASEIN PAINTS. | 73

/

burned lime is gradually slaked with water at the above-named
temperature, so that it crumbles down to a fine dry powder.
Of this powder 14 parts are mixed with 74 parts of water, tri-
turated, and then filtered through blotting-paper. The two
ingredients are finally mixed together by stirring, which is
continued until the mass, originally somewhat stiff, has
attained workable consistency.

PURE CASEIN PAINTS FOR WALLS, ETC.

1. Black. 2. Yellow.
Casein varnish 50 parts by weight. Casein varnish ; . 50 parts.
Lampblack . 13 a Pa Chrome yellow ; ee es | ae
3. Chalk White. 4, Fine White.
Casein varnish ; . 50 parts, Casein varnish ‘ . 50 parts,
Chalk . p : nbraitig - eaeele White lead . : Here) Sacer
5. Red. 6. Cheap Red.
Casein varnish « 42 60 para. Casein varnish : . 650 parts.
Vermilion r : Sp Oe Tops Colcothar ; ; of Os
7. Blue. 8. Green.
Casein varnish ; ; 50 parts. Casein varnish , . 50 parts.
Berlin blue. : ‘ Bugs White lead. : ; 14 | ;;
White lead . : - ae Chrome green . ; i SF iss.
9. Ochre.
Casein varnish ; F 50 parts.
Ochre. ; 2 ‘ gp sa

CASEIN PAINTS FOR WooDWORK AND IRON.

1. Black. 2. Yellow.
Casein varnish : . 50 parts. Casein varnish ; o BO parts.
Black, ground in oil 0 Oey Chrome yellow, ground in
oH: “ ‘ é 96. 3
3. Chalk White. 4. White Lead.
Casein varnish ‘ . 50 parts. Casein varnish ‘ 50 parts.

Chalk, ground in oil 3 SOF White lead, ground in oil 50 ,,

74. CASEIN.

5. Red. 6. Blue.
Casein varnish ; . 50 parts. Casein varnish E . 50 parts.
Vermilion, ground in oil . 50. ,, Berlin blue, ground in oil 40 ,,
OPees
Casein varnish ; . 100 parts.
Colcothar, groundin oil. 50 ,,
7. Green. 8. Ochre.
Casein varnish ; : 50 parts. Casein varnish : . 110 parts.
Chrome green, ground in oil 50 _,, Ochre, ground in oil Aida «, | Sore 4

Casein paints, drying without gloss, are therefore suitable
for painting house fronts, iron and other metal work, and |
also for canvas. Their most advantageous application is for
the purpose first named, since they can then be prepared in
large quantity, used up at once, and will dry in a few hours.
They enter into combination with the underlying plaster and
are thereby rendered more durable.

The paints prepared as above are thinned to a workable
consistency with further quantities of casein varnish, and are
then laid on as evenly as possible, in the same way as oil
paint. The first coating will dry in about an hour, and a
second coating can be applied a few hours later. This
property of drying quickly is a great point of superiority over -
oil paint, since casein paints can, therefore, be used during
unfavourable weather and seasons without any fear of the
paint washing away or peeling off. These paints are also
inodorous, whereas the smell of varnish and turps clings to
oil paint for a long time.

For woodwork the paint is prepared in the same way,
but three or four coatings are necessary to cover the wood
properly. It can then be grained and varnished, just as in
the case of oil paint.

Ironwork must be coated with casein oil paint, as the
ordinary casein paint will not adhere to the metal. The iron
should be freed from rust and the paint applied in a thin

CASEIN PAIN'TS. 75

coating. Owing to the rapid drying of the paint it is less
subject to injurious influences, but should be protected from
these as much as possible to prevent the paint washing or
peeling off and thus defeating the object of. the application.

Casein Distemper Paints.—During late years there has
been a considerable development in the use of distemper
paints, which are sent out by many makers under a variety
of fancy proprietary names in the form of powders or paste,
which only require thinning out with water to make them
suitable for use, many of these being char&cterised by the
fact that they will withstand a reasonable amount of washing
or rubbing. Distemper painting, or the use of various pig-
ments mixed with water, has long been practised ; but applied
in this simple way, the pigments were loose and rubbed off
badly, therefore to fix them on the surface it has long been
customary to add size or glue. But the development of the
dairy industry, and the desire to utilise all the constituents
of milk, has led to the production of casein in considerable
quantities, its employment as a fixing agent to distemper
paints being the consequent result.

Water-Colour Paints.—For indoor use: 100 parts by
weight of casein are mixed with 15 parts of 90° to 92° Tw. soda
solution and 885 parts of kaolin, chalk, or other white pig-
ment. For outdoor use: 90 parts of casein are mixed with
40 parts of powdered slaked lime, 74 parts of silica, and 865
parts of kaolin, chalk, or other white material.

Casein-Silicate Paints.—Casein-silicate paint is a mixture
of casein with potassium or sodium silicate (‘‘ water-glass’’),
the casein being dissolved in caustic soda or potash and
stirred up with the alkali silicate and a sufficient quantity of
diatomaceous earth until the resulting grey-brown mass is
perfectly homogeneous. The paint can be tinted by the
addition of lime-proof colours up to 10 per cent. It forms
a useful indoor and outdoor coating for stone, brick, and

76 . CASEIN.

fresh dry plaster (lime or cement), and it can also be very
advantageously used in very damp rooms. Cheap fireproof
paints for wood, canvas, etc., can easily be made by mixing
these silicate paints with asbestos or other fireproof material.

The addition of casein to water-glass causes a gradual
solidification, so that, unlike ordinary silicate paints, the
coating is not completely hard in a few hours, but only at
the end of two to three days. This circumstance is owing
to the formation of a compound between the casein and the
alkali of the water-glass and the separation of colloidal silica
and casein. If the paint is desired to possess greater elasticity
it is advisable to add a small quantity of saponified water-
glass along with the ordinary silicate solution ; while a higher
gloss may be obtained by adding a solution of shellac and
water-glass.

Though silicate paints offer many advantages over oil
paints they have failed to make much headway up to the
present, owing to the difficulties encountered in their pre-
paration and use. Among these difficulties are the low range
of colours attainable and inability to stand the weather. In
fact, only the following pigments have been found suitable
for use in silicate paints :—

For Blue.—Ultramarine and smailt.

Yellow.—Barium chromate, uranium oxide, and ochre.

», Black,—Lampblack, boneblack, and graphite.

3, Green.—Chromic oxide, ultramarine green, and cobalt green.

», Red,—Iron reds.

3, Orange.—Chrome red.

Brown,—Coleothar, burnt sienna, brown manganese oxide; these do not
curdle the silicate,

For white, zinc white, white lead, and barium sulphate
can be used only in small quantities and must be mixed with
the silicate just before application. |

The reds, chrome red and red lead, affect the silicate less

CASEIN PAINTS. 77

rapidly, but still too quickly to permit of their use to more
than a limited extent. :

On the other hand, an admixture of casein with silicate
paint retards the hardening of certain pigments, especially
white lead. The mixture is easily prepared by triturating
fresh curd with a little sodium silicate (density, 33° B.) to
form a uniform mass and then stirring in the remainder of

the silicate.

Milk Paints.—Pigments are mixed with milk and water
to workable consistency, and then applied to a surface prev-

iously coated with silicate paint.

When the milk paint is

dry, it is topped with silicate paint by spraying.

1. White. 2. Grey.
MilE 5253 FA AY Spars: Mikey ec, 3 parts.
Water . : é ‘ : ere Water . : 4 : ie
Zine white . : ; ee Zine white . 2 ; Bi Cae ie

Lampblack . : F e045
3. Light Green. 4, Yellow.

Milk ; ; é 4 2 parts. Milk. ; ‘ < 2 parts.
Water . é ; : Oo. Water . ; A : A
Zine white . z 5 yi Sa Ochre . 7 , ‘ 10° sy
Green earth . ‘ _ ws

5. Brown. 6. Red-Brown.
Milk. ; : ; 2 parts. Milk ., ; ‘ : 2 parts.
Water . A 3 } ‘ae Water . 3 j : Ba;
Umber . ; ‘ j 10: ,, Burnt sienna : j O34

7. Blue. 8. Black.
Milk . , ‘ P 2 parts. Milk F ‘ ; , 2 parts...
Water’. = ; : 3 Water . : ne ets a: Saar a
Ultramarine . ; i Wes Ivory black . : 4 £00 > 35

9, Red. or-—
Mie es oR gee ee oh eee,
Water . ; j : 62° Water . ; ‘ : B53
Vermilion —. ; ‘ 25 * .; Colcothar ‘ : P 1D: =

78 : CASEIN.

No particular difficulty attaches to the compounding of
pigments for casein-silicate paint, but care should be exercised
not to employ pigments that harden rapidly.

CASEIN-SILICATE PAINT RECIPES.

1. Blue. 2. Yellow.
Casein-silicate vehicle 5 parts. Casein-silicate 5 parts.
Ultramarine . Pe Ochre Br ips

8. Black. 4. Green.
Casein-silicate 8 parts Casein-silicate 5 parts
Bone or ivory black ae Chrome green nt

5. Hed. 6. Brown.
Casein-silicate 5 parts Casein-silicate 5 parts.
Coleothar iis, Brown manganese oxide orn

7. White. 8. Grey.
Casein-silicate 5 parts Casein-silicate 5 parts.
Zine white Bary Zine white Bo

Lampblack . oe
Of

Casein-silicate 6 parts.

Zinc white er

Lampblack . aS

Ultramarine . ey

Trojel’s Boiled Ow Substitute—H. Trojel proposes to
make a cheap substitute for boiled oil by carefully mixing
together 100 parts of casein, 10 to 25 parts of soap solution,
and 20 to 50 parts of slaked lime, 25 to 40 parts of turps
being afterwards stirred in gradually, and the whole thinned
with water to the consistency of boiled oil. If this pre-
paration is to be kept for some time, a little ammonia, is
added, to prevent the casein settling out. The mass dries
very quickly and can be mixed with colour for coating damp _
brick or wooden walls. It also adheres well to metal, and
becomes insoluble in water on drying.

CASEIN PAINTS. 1

Calsomine Wash.—This preparation consists of a mineral
base in combination with a binding medium having the
property of solubility in water but reverting to a perfectly
insoluble product when exposed to the air in the form of a
coat of paint. This paint is therefore waterproof, possessing
the properties of oil paint in this respect and being also
capable of withstanding the influence of the weather. The
pigment is a white or coloured powder consisting funda-
mentally of magnesium silicate or talc, which is added to the
binding medium in the proportion of 90 parts to 10. It is
also practicable to use 20 parts of lime, 70 of chalk and 10
of binding medium ; these proportions again may be modified
in turn. The binding medium is compounded of casein and
lime, the former being obtained, as a dry white powder, by
treating milk with an acid at 100° F. Sixty parts of this
powder are mixed with 20 parts of dry slaked lime, where-
upon the casein becomes soluble in water, though this
»property disappears on exposure to the atmosphere. Any
convenient body colour may be incorporated with the mix-
ture, and when the whole is thinned with water it furnishes
an easy working and waterproof paint.

Quick-Drying Casein Paint—When mixed with such
yolatile substances as turps, petroleum, benzol, etc., dis-
solved casein acquires the property of drying very quickly.
Hence, by preparing a solution of casein together with oil
or balsam, and thinning it with petroleum, a product is
obtained which is quick drying as well as highly elastic.

A mixture of 8 parts of this medium, with about 10 of
zinc white, lithopone, etc., forms a very useful light paint
for outdoor or indoor use on woodwork or metal. It is
worth noting that the addition of petroleum, benzol, or the |
like, causes the particles of the paint to penetrate deeply
into wood and the fine joints in ironwork without stopping
the circulation of air. This protects the iron from rusting ;

80 CASEIN.

while the antiseptic effect of the petroleum preserves wood
from rotting and fungoid growths. Oil paint is soon spoiled
in appearance when exposed to ammoniacal exhalations, but
they have no effect on petroleum-casein paints. The latter
dry readily and do not. darken in course of time; neither
does the smell of petroleum cling to them very long.

Petroleum may be replaced in these paints by benzol,
turps, naphtha, xylol, and ethereal oils such as oil of spike
lavender, etc. When the paint is to be used for outside
work on timber or brickwork an addition of linseed oil is
desirable, while the paint should be thinned down considerably
so as to allow the particles to penetrate deep into the under-
lying material.

In places exposed to mechanical or atmospheric influences,
or on damp walls, these quick-drying casein paints will be
found highly advantageous.

Boiled Oil Substitute—A substitute for boiled oil may
be prepared by adding to 100 parts by weight of casein 10.
to 20 parts of a 1 to 10 per cent. solution of soap, followed »
by 20 to 25 parts of slaked lime, the mixture being carefully
kneaded until a homogeneous mass is formed. It is after-
wards thinned by the gradual addition of 20 to 40 parts of
turps and sufficient water to reduce the consistency to that
of boiled oil. If the varnish is to be kept for any length of
time, a little ammonia should be added to prevent the pre-
cipitation of the casein-lime complex. This substitute is
much cheaper than boiled oil, and dries so quickly that
two coatings of the paint made with it can be applied in

immediate succession.
Casein Paint (German patent 186,272: A. Bronstela:
Hamburg).—Casein, or other albuminate, is mixed to a stiff
pulp with quicklime, chalk, and water, a slight current of air
being then blown through the mass until it becomes fluid
and gives off a faint odour of ammonia. Chlorinated, brom-—

CASEIN PAINTS. : 81

inated or iodated oil is next stirred in, and the mixture is
either converted into powder by trituration with chalk, or
else diluted with water to a workable consistency. The oil
is chlorinated by treating it with chlorine water and agitat-
ing the mixture until the oil has taken up a large pro-
portion of chlorine. When bromine or iodine is employed,
an alcoholic solution is used, the solvent being afterwards
expelled.

Water-White Casein Varnish (German patent 200,919:
M. Fehringer, Fuerth),—When an alcoholic solution of resin
is mixed with an ammoniacal solution of casein, the resulting
varnish, though drying with a high glass, is always cloudy,
the material in suspension being incapable of removal by
settling or by the use of clarifying agents. The inventor,
however, claims that by exposing such varnish to a tempera-
ture below the freezing:point of water for some little time, it
_ will separate into a clear, water-white layer and a cloudy
stratum, the former being then removed by decantation.

Casein Paint—Commercial casein 5 parts, barium sul-
phate 150 to 200, slaked lime 10, gum-tragacanth 5, glycerine
soap in powder 3. A similar recipe to this in which for-
maldehyde is used is as follows: Casein 5 parts, ammonia
0°25, water 50, formaldehyde 0°5, barium sulphate 50 or
upwards, linseed oil 5. The casein is mixed into a smooth
paste with a little water, and thinned with more water.
The lime or ammonia is added and causes the liquid to
become thicker. Finally the pigment is incorporated, and
the formaldehyde, if this is used.

Ring’s Cold-water Paint.—G. R. Ring, of New Brighton,
mixes casein or some other albuminous substance with a
filling of levigated chalk, gypsum, lime, talc, pigments, etc.,
the whole being ground together.. Glue or similar material
is then mixed with hydraulic lime, and ground. The two

fundamental ingredients thus obtained are mixed together,
6

82 CASEIN.

with a further quantity of filling material, to form the paint,
which is thinned with water for use. _

Formolactin.—Under this name the Aktiengesellschaft
fiir chemische Industrie ‘‘ Union,” of Vienna, has put on the
market a liquid intended for use as a wash or for printing on
paper or analogous material in order to make the same
washable, waterproof, and dustless. Formolactin is a con-
centrated solution of casein and formaldehyde, thick and
milky in appearance.

When applied as a coating on any “surface, formolactin
also acts as a disinfectant. This disinfecting action can be
renewed at any time by washing the surface over or spraying
with a 1 per cent. solution of formaldehyde, without the use
of any special apparatus, and without injuring the paper or
any object in the room in the slightest degree.

On this account formolactin is highly suitable for painting
bedrooms, hospital wards, smoking-rooms, living-rooms, etc.,
the cleaning of which is greatly facilitated by its use.

In consequence of its content of formaldehyde, formo-
lactin destroys any nest of insects present in crevices in the
walls to which it is applied.

The instructions for using this preparation are as
follows :—

Formolactin is diluted with a 2 per cent. solution of
formaldehyde, prepared by dissolving 5 parts of commercial
40 per cent. formaldehyde (formalin) in 95 parts of water.
The degree of dilution depends on the amount of gloss
desired and on the absorbent character of the wall-paper.
Speaking generally, equal parts of formolactin and the said
2 per cent. solution of formaldehyde will be suitable for good
ordinary wall-paper. Ifa higher gloss is desired or the paper
is more absorbent, then 1 part of the 2 per cent. solution can
be taken to 2 parts of formolactin. ‘For a dull gloss and less
absorbent paper the dilution may be increased to 1 : 2.

CASEIN PAINTS. 838

A wide, soft brush is used, and no more of the paint is
laid on than the paper will take up, otherwise it will trickle
down and a patchy appearance will be presented.

The colour of most wall papers is made to look brighter
by a coating of this preparation, a fact which should be
borne in mind when the paper is being selected.

After applying the coating it is left three to four hours
to dry, and the room is afterwards well ventilated in order
to remove the smell of the formaldehyde. This may be
accelerated by sprinkling ammonia on strips of wadding and
allowing it to evaporate inside the room. The smell of
formaldehyde, however, is by no means injurious to health.

If the first coating does not produce the desired lustre, or
fails to cover the paper properly, a second coating, properly
thinned, maybe laid on without affecting the durability of
the covering.

The best way to wash and clean wall papers coated with
this preparation is with lukewarm soap and water, to which
4 to 4 per cent. of commercial formaldehyde has been added
as an antiseptic. —

Waterproof Paint for Playing Cards.—Playing cards
may be coated with a mixture of satin white—precipitated
calcium sulphate—and an alkaline solution of casein. The
coating is waterproof and washable, whilst still leaving the
paper sufficiently absorbent to allow the cards to be printed
in the usual way.

The best mixture for this purpose consists of 80 parts of
satin white, 16 of casein, 2 to 4 of caustic soda or ammonia,
and 25 or more of water. The inventor of the preparation
believes that the satin white combines with the dissolved
casein in such a manner as to render the latter insoluble
when the coating has been applied and allowed to dry for
some time.

This coating is said to be particularly useful in imparting

84 CASEIN.

to playing cards the desired enamel-like appearance, and to
be capable of taking the most delicate multiple colour print-
ing. The satin white may be partly replaced by blanc fixe.

Casein Colour Lakes.-—The use of casein as a precipitant
is useful in making colour lakes, kaolin being employed as
the substratum. For instance, Dreher recommends grinding
to a paste 30 parts of finely ground kaolin and 20 of lukewarm
water, followed by a repetition of the operation with an
addition of 80 parts of dissolved casein (10 parts of casein,
20 of water and 1 to 2 of ammonia). One hundred parts of
dye solution (0°5 per cent. strength) are next added and well
mixed, the whole being then treated with 2 parts of a 1 per
cent. solution of tin tetra-chloride, added drop by drop.
After being washed and pressed, the precipitate is dried at
60° C., or at 80° to 100° C. if the dye will bear that tempera-
ture. Both acid and basic aniline dyes can be precipitated
on any substratum by this method. The resulting lakes are
very bright in colour and are very fast to water. ‘Tin tetra-
chloride may be replaced by other salts having an acid
reaction, such as aluminium chloride, tin acetate, etc., but the
acetate must be free from any excess of acetic acid, since this
exerts a solvent action on the lake. The method is pavr-
ticularly useful for precipitating rhodamines and eosines,
which it converts into extremely brilliant fine red lakes that
are non-poisonous. The casein lakes also merit attention for
coloured bookwork and litho printing, and for wall-paper
and calico printing. 7

Paint for Marking Bags, Iron Barrels, Cases, etc.—A
good paint which will adhere to fabrics, paper, wood, sheet-
iron, etc., and is therefore suitable for marking and stencilling
cases, wrappering, jute sacks, etc., is prepared in the follow-
ing Manner :—

About 20 parts by weight of water are heated to boiling
in a glass vessel, and 1 part of aniline dye is stirred in, eosine

CASEIN PAINTS. 85

being used for red, and phenol black or deep black for black.
When this is dissolved, 2 parts of soluble casein are stirred
in. If the liquid appears too thick when cold, and therefore
difficult to lay on with the brush, it must be diluted with a
corresponding amount of hot water.

The aniline dyes may be replaced by logwood solution
and potassium chromate; but tincture of gall-nuts is not
suitable for this purpose.

Stencilling paste is made by mixing pipeclay with ivory
black or lampblack. The pipeclay (kaolin) is_ suitably
coloured with aniline dye, carefully incorporated ‘with the
ivory black or lampblack, and then introduced into a thin
solution of casein. After being put through a paint mill,
the mass is packed in tin boxes.

Caseon-Cement Paint.—Hiausler recommended English
Roman cement for this purpose. The boards to be coated
are left unplaned, and pillars and beams are gone over with
the roughing plane; the following method is recommended;
-and the wood will not only look like stone, but behave as
though actually petrified :—

T'wo parts of English Roman cement is stirred up with
4 parts of washed scouring sand, 2 parts of fresh curd, and

4 parts of skim milk, no more being made ready at a time
than can be used up in an hour. While the mass is being
applied, it must be kept continually stirred by an assistant in
order to prevent the sand from settling to the bottom. The
coating is laid on as thin and smoothly as possible, and as
soon as it is dry is followed by a second. In summer it dries
quickly and sets as hard as stone. Finally, woodwork that
is to stand upright is coated with a mixture of boiled oil and
an earthy pigment, a double coating being applied to sloping
woodwork, and three or four coats on horizontal or exposed
work that is liable to be trodden on. ;

For smoothly planed woodwork, Hiusler used the

86 CASEIN.

subjoined mixture with equal success: English Roman
cement, 4 parts; fresh curd, 2 parts; buttermilk, 14 parts;
_the whole being well stirred together and made up in suffici-
ent quantity to last only for a short time. The Roman
cement must be of good quality, preferably freshly burned.

CHAPTER VI.
THE TECHNICS OF CASEIN PAINTING.

CASEIN painting is based on the principle that casein pos-
sesses the property of forming extremely resistant and
permanent compounds, both with the pigment and also
with the substratum. The subject is, therefore, divisible into
several sections, viz. :—

1. Preparation of the ground. |

2. Preparation of the binding medium.

- 3. Preparation and application of the casein paint.

Although from its nature casein painting is no more diffi-
cult than any other branch of the art, certain precautionary
regulations must nevertheless be observed in the preparation
of the ground or surface to be painted on. In the first
place, surfaces of solid and granular lime- or cement-plaster ;
surfaces already coated with a layer of oil paint, and sur-
faces consisting of ordinary building stone, or ornaments of
clay, wood, sheet metal, etc., must be thoroughly cleaned
before painting is begun. If casein paint is to be applied
to rough lime plaster the latter must be brushed over with
diluted milk which has been carefully skimmed and mixed
with the right quantity of water. Defective places in the
plaster of house fronts must be patched up with mortar, or
preferably with a mass composed of 1 part of patent lime
and 35 to 4 parts of pure sand. Patent lime is made by

allowing solutions of tin and zinc chloride to act on lime,
(87)

88 CASEIN.

and it will also bear additions of ground marble, cement, and
earthy pigments.

New cement plaster, or such as exhibits fine cracks,
moisture or efflorescent salts, is best washed over with dilute
hydrochloric or sulphuric acid (1 part of acid to 8 to 10 of
water), and after a short time has elapsed wiped with a rag
and left to dry. A preliminary coating of caoutchouc butter,
Kesserl’s fluoride paint or diluted blood, etc., is also advisable.

For indoor use the ground should be impregnated with
alum, 1 part of which is dissolved in 5 of hot water and then
diluted with 10 parts more of the latter. This soaking,
however, is only needed for walls that have previously been
coated with lime paint or distemper. Gerhardt’s paint soap
is also recommended for the same purpose, its antiseptic
properties and power of rendering animal matter insoluble
fitting it for use on articles where fungoid growth is possible.
The penetration of this preparation into the ground increases
the durability of the casein paint, especially if the alum im-
pregnation and Gerhardt’s soap treatment be combined.

Joints, cracks, or holes in brick or woodwork must be
filled up with undiluted casein paint; but large fissures are
best stopped with casein putty.

If there are any damp places in the plaster, and it is
desired to prevent them showing through, they should be
impregnated with a thin solution of shellac before the paint
is applied. Certain impregnating varnishes are also sold for
this purpose.

Metals, such as. zinc, copper, and iron, may be painted
with quick-drying casein paints without any preparation,
provided the surface is clean and not covered with a film of
oxide. Should this, however, be present in the form, say of
iron rust, it must be removed, by washing with caustic soda
and petroleum or by scratch-brushing.

Finally, in the case of objects that are to be decorated,

THE TECHNICS OF CASEIN PAINTING. 89

it is necessary to provide a non-absorbent surface, to form
a suitable ground for painting on. A special preparation is
required for fresco painting, it being essential for the ground
to be thick and dry, so as to prevent the appearance of any
efflorescence from the brickwork underneath. For this
reason, the plaster should be composed of as many layers as
possible, each dried separately. Two to four strata of coarse
plaster and an upper one of fine plaster are usually sufficient.
Each layer should be thoroughly dry before the next one is |
put on, the surface being well moistened with water just
before the succeeding coating is applied. The bottom layer
must be coarse grained and thicker than the others, the
total thickness being 1 to 2 inches.

The coarse plaster is prepared of mortar from 1 part by
volume of patent lime and 2 parts of clean, coarse, sharp
sand (preferably quartz sand), burnt fireclay or powdered
stone, together with about 10 per cent. of good Portland
cement. This mortar is apphed to the wall surface, beaten
with a wooden bar to drive out air bubbles, and left to dry
for as long as possible. On this surface, after wetting it with
pure or boiled water that has been allowed to cool, the fine
plaster is applied, the mortar for which is compounded of
1 part patent lime, 1 part fine, sifted, dust-free, clean sand
and 1 part marble sand, the whole mixed with water that
has previously been boiled. This mortar is also beaten to
expel air bubbles in the mixing trough, and is then laid on
over the coarse plaster. As soon as the surface has dried dull,
it is wetted with a little boiled and cooled water and worked
over with a smoothing board, any residual roughness being
smoothed away by a sheet of zinc after the mortar has set to
such an extent that it merely yields a little under the pressure
of the finger. Directly this upper layer is dry it can be
painted on with the necessary casein paints, and retouched
with the same colours after drying.

90 3 CASEIN.

To facilitate the fresco painting the upper layer of plaster
can be put on in sections, or else kept soft for a considerable
time by wetting it with water that has been boiled, or by
hanging wet cloths over the surface. This prevents the too
rapid crystallisation of the lime, which would otherwise
occur.

Dry fresco painting is performed in the following manner:
Old or dry plaster walls are scrubbed with a stone until the
upper surface has been worn away and the sound absorbent
plaster is reached; but if the crust is sound and rough
grained it need not be removed. A mixture of fluid casein
medium, white outdoor cement and 10 per cent. of calcined
magnesia is then mixed and diluted with previously boiled
and cooled water, the first coating being thinner than the
others ; and, the wall having been damped with re-cooled or
rain water, several coatings of this mixture are applied in
succession. As soon as the surface has dried dull, several
coatings of ground colour are laid on, and the decorations
and painting are then applied. :

According to Martin, the aforesaid outdoor ‘cement is
also known as ‘‘ white Portland cement,’ and is prepared by
mixing 1 part of iron-free kaolin, 3 to 5 parts of pure |
white chalk, followed by 2 to 5 parts of gypsum or 3 to
5 parts of magnesium chloride. The ingredients, wet or
dry mixed, are calcined in an oven.

Probably the best method of imitating the old Pompeian
wall paintings in character and durability is the dry fresco
process of Gerhardt. In some cases, however, it is possible
to dispense with scouring the walls beforehand, replacing
this treatment by the less troublesome process of soaking the
walls several times over with paint soap at the completion of
the work, this treatment increasing the brightness of the
colours and improving their character and durability.

After the impregnated surface has dried it may be polished

THE TECHNICS OF CASEIN PAINTING. 91

to a dull gloss witha brush. The precautions specified must,
however, be adopted in order to secure the intimate connec-
tion between the painting and the ground, so necessary to
render the painting durable.

— Compounding the Binding Medium.—Next to the sub-
stratum, the most important thing in casein painting is the
medium, since on this depends not only the durability of the
paint but also several of its chief characteristics. Hence, it
can be easily understood that the composition of the medium
may vary. in many ways, according to the purpose for which
it is intended. Thus, one used for ordinary painting on walls
is not also suitable for decorative painting, whilst, on the
other hand, a medium for indoor work cannot be employed
for outdoor painting.

Casein and its properties have been already described,
therefore all that is now necessary to mention is that the
dry casein must be converted intoa soluble form before it can
be used as a binder.

The usual solvents for this purpose are caustic potash
or soda, borax, sodium bicarbonate, ammonia, potassium or
sodium silicate (water-glass), slaked lime, cement, etc. Since
it would not pay the painter to prepare casein from milk,
it is preferable to use the commercial soluble casein. A
simple solution of this is made by adding to 1 part of casein
0°3 to 0'4 part of strong ammonia, the solution being pro-
tected from putrefaction by means of a little carbolic acid.
To convert these solutions into a usable medium they are
treated with a little alkaline solution of rosin, containing a
small admixture of soap or wax. These latter substances
are intended to surround the particles of pigment with a pro-
tective envelope against atmospheric influences. A medium
prepared in this way is suitable for fine artistic painting
indoors, enabling different pigments to be used and imparting
to these a fine sheen.

92. CASEIN.

Another casein medium, for which, however, the same
claims cannot be advanced, is prepared by intimately mixing
an alkaline solution of casein with diatomaceous earth (kiesel-
gukr). This has the drawback of becoming dark-coloured in
time, and not being suitable for use with certain pigments,
such as Berlin blue, though it can be usefully employed for
coloured paints and rough ornamentation work. .

On the other hand, compounds of fatty acids with
alumina, and similar substances, are not advisable. Prof.
Linke, in his work on painters’ colours, says of these that
though, when first dried, they form a dense, horny layer
which repels water, the colours prepared with their aid soon
alter in molecular structure on exposure to the air, and fall
to powder, which is readily oxidised by atmospheric oxygen,
becoming chemically changed and therefore rendered useless.

If dissolved casein is emulsified by oil, balsams, or fats,
together or separately, the resulting medium is distinguished
by the property of leaving the natural tone of pigments
unaltered. A casein medium of this kind, or one treated
with rosin, cannot, of course, be thinned with water, but only
with benzol, petroleum, turps or other volatile substances.

All the media hitherto described are fnore or less restricted
to use for indoor painting. For outdoor use the casein must
be incorporated with substances with which it forms insoluble
compounds. ‘The best known of these is slaked lime, which
has been already mentioned in connection with cold-water
paints (q.v.). Cement also forms with casein a particularly
resistant and effective binding medium, a patent for making
these media having been granted to Ant. Richard of Diissel-
dorf. According to this specification, casein, properly freed
from fat, is mixed with an antiseptic, ¢.g., formaldehyde,
carbolic acid or the like, and then carefully ground along
with water. ‘The resulting thin liquid mass then receives an
addition of cement proportionate to the amount of casein

THE TECHNICS OF CASEIN PAINTING. 93

present, the whole being well mixed and left to stand until
the thicker, heavier constituents have settled down, where-
upon the supernatant liquid, which forms the medium, is
separated by decantation. This liquid has not the slightest
action on the most sensitive body colours, and its binding
power is unaffected by formaldehyde. _It renders the colours
thoroughly workable and imparts great durability, so that
they can also be used for outdoor work, being able to with-
stand the weather. These colours are also suitable for use in
calico printing, since they are insoluble in water when once
dry. The sedimental matter can be ground and used as a
cover paint. 7

The Preparation and Application of Casein Paints.—
To prepare artists’ colours with casein, all that is necessary
is to take one of the media just described and mix it with the
appropriate pigments. The pigments most suitable for white
are: barytes, China clay, Paris white, lithopone, and zinc
white; for yellow: cadmium yellow, golden or pale ochre,
Naples yellow, ‘‘ satinober,” Schiitt yellow, and Terra di
Siena; for red; colcothar, carmine, chrome red, fast red,
Indian red, madder lake, red lead, signal red, Terra pozzuoli,
vermilion, and vermilionette ; for brown: asphaltum, Cassel
brown, dark ochre, manganese brown, Terra di Siena, umber,
Vandyke brown; for blue; indigo, cobalt blue, blue-green
oxide, and ultramarine; for green: chromic, oxide green,
green earth, cobalt green, permanent green, Schweinfurt
green, and emerald green; for black: ivory black, bone
black, lampblack, and Paris black.

To prepare small quantities, the binding medium is mixed
with the dry pigments on a plate or sheet of glass, or else
they are ground with a muller or in a paint mill. The
resulting paint is thinned to a workable condition with
boiled and re-cooled water at the time of application.

For making up large quantities at a time, the dry colours

94 CASEIN.

may be saturated with water and then mixed with the casein
preparation. In the case of heavy pigments, this precaution
is advisable, since the mixture is easily rendered too thin.
The colours, however, adhere better when mixed with the
binding medium dry, the particles, in that event, absorbing the
vehicle instead of water, thus becoming more completely
enveloped by it.

Some of the organic colouring matters, e.g., bone black,
Cassel brown, etc., which form a good nutrient medium for
mould fungi, require an addition of 4 to 1 per cent. of car-
bolic acid, 1 per mil. of formalin, or about 2 to 3 per cent. of
salicylic acid solution, to the water to preserve them ; this ad-
mixture causing no harm in the case of other colours.

Although not essential, it is advisable to add a little lime
to casein paints, especially when they are in paste form or
for outdoor use.

If the amount of lime to be added is large, it is better not
to make up a large stock of the paint, but only just enough
for two to three days’ consumption, since the insolubility of
the paint film becomes greater when the combination of’ lime
and casein is fresh but is lessened when the mixture is stale.

The proportions of medium and pigment cannot be arbi-
trarily laid down, owing to the divergent requirements of the
various pigments, and also because one and the same pigment
varies in this respect, according to its origin and mode of pre-
paration, apart from the fact that the power of the different
casein media is a variable quantity. _

Chalk and calcined earth pigments require a larger
proportion of casein medium than lithopone, white lead, etc.,
whilst ochre and other raw earths usually need less. Light
colours generally take less than dark ones, and inorganic
pigments less than those of organic origin. Usually the
quantity of medium varies inversely as the specific gravity
of the pigment just as in grinding oil paints.

THE TECHNICS OF CASEIN PAINTING. 95

The proportion of medium also varies according to the
surface to be coated. For example, a larger proportion may
generally be used on solid plaster and other solid substrata,
such as metal, cement, oil paint, paper, canvas, etc., than on
a surface that readily chips, such as plaster of Paris. In
any case, if the paint is too strong it is very liable to cause
the weak substratum to break away, chip, or peel off, especially
when organic colours are used. .

For painting on solid or prepared plaster, rough wood, etc.,
sufficient casein medium must be taken for the paint to adhere
strongly to parchment paper when dry, so that it does not peel
off when the paper is folded, and will stand the action of a
strong jet of water at the end of about twenty-four hours.

To ascertain whether the right proportion of medium has
been used, a small quantity of the paint is brushed on a
sheet of writing or printing paper. If the paper is found to
have shrunk much when the paint is dry, too much medium
has been used. |

As regards the handling of the brush, this is similar to
distemper work, only that the brush must be more frequently
cleansed with soap. A peculiar kind of curdling can be
noticed when the paint in the can or brush has become too
dry, and an attempt is made to reduce it with water. In such
a case the brush must be washed with soap and water and a
fresh quantity of paint taken. Hence both paint and brush
should be kept moist, and the colours on the palette frequently
sprayed with water, the can being kept covered up, and
preferably fitted with an airtight lid.

In connection with the storing of casein paints the fol-
lowing points may be mentioned: In order to prevent the
medium from drying, the can is either turned upside down, or
else the surface of ‘the paint covered with a layer of water. ©
The paint, however, must not be thinned with this water, or
a separation into layers may easily occur.

96 CASEIN.

If the paint and medium separate in the can, they may
be remixed by stirring or shaking, but any skin that forms
- should be thrown away.

Casein paint that has partly or completely dried in the
can is unfit for use, and it is therefore necessary to guard
against this by covering the surface with water or closing
the cans airtight.

If the medium becomes frozen in winter it should be
slowly rewarmed over a water bath and then stirred up well.

The application of casein paints is performed in the fol-
lowing manner :—

After the ground has been suitably prepared, the outlines
are sketched with crayon and coloured in, any excess of
crayon being wiped off with a soft clean cloth.

The well-thinned paint is then laid on, as light in colour
as possible. The oftener the coating is repeated, the more
attractive the effect produced, whereas, if the paint is too
thick the effect is diminished and it readily tends to peel off,
this being especially the case with dark colours containing
an excess of the casein medium, though it may also occur
when the other extreme is in question. This must be tried
and modifications made accordingly before beginning the
actual work of painting.

Both wide bristle brushes and fine long sable brushes are
used. If, when the work is finished, some of the tones do
not harmonise, they can be modified by working over the
whole portion.

Thus, if one tone be too light and warm or too bright,
it is worked over with ivory black alone, other alterations
being made with deep colours, reduced to a thin paste with
water and quickly laid on with the brush. In these opera-_
tions the greatest cleanliness is necessary, both with the
colours and with the cans and other utensils.

To paint frescoes on canvas, a rough canvas is coated

THE TECHNICS OF CASEIN PAINTING. 97

with undiluted casein preparation and painted in quite wet
with colour that has merely been mixed with water without .
any casein medium. At the same time the under layer is
kept well moistened with water throughout the entire process.
If the dried paint is to be topped, the surface must be sprayed
with the casein medium diluted 8- to 10-fold with water, and
the paint applied as above.

In painting pictures on outside work, the casein medium
prepared with the assistance of oil, balsams, and fats, or wax
and resin is used. For the first coating on absorbent sur-
faces this is mixed with ordinary amber varnish which im-
proves the drying properties and furnishes a handsome
gloss.

If, on the other hand, drying is to be retarded in order
to be able to work the colours together longer, then a little
oil is added to the medium or the same is mixed with oil
paint. Should the surface nevertheless get too dry, the
true shade of the colours may be revealed by moistening
with turps.

To coat the pictures with glossy varnish, as though they
were oil paintings, a coating of glossy varnish or some other
thick varnish must be brushed in, and when this is dry it
should be covered by a second coat of varnish.

The varnish may be replaced by a coating of wax solu-
tion, the dried layer being heated to melting-point in order
‘to increase the durability and powers of resistance. The
same purpose is also setved by the paint soap and impreg-
nating varnish, as well as the formaldehyde solutions already
mentioned, though these can be used only on casein paintings
that are free from fatty matters. :

A fixative of this kind can be prepared by treating an
aqueous solution of casein and borax with absolute methyl
alcohol free from acetone, the solution being left to stand for
a long time and separated from the sediment.

7

98 CASEIN.

According to Chialiva and Dupot, in their patent specifica-
tion, this fixative has the property of drying quickly and not
too glossy.

Another weatherproof varnish for preserving paintings
is obtained, according to the patent of Gebriider Pilz, by
moistening collodion cotton with methyl alcohol and then
dissolving it in a solution of camphor in alcohol containing
spirit of turpentine.

Formaldehyde, too, has latterly been recommended as
an excellent means of rendering casein paintings insoluble
in water (see Formolactin). If a dry picture, painted with
casein paint, be exposed to the vapours of formaldehyde, the
agglutinant in the paint (casein, glue, or albumen) quickly
becomes waterproof.

Before closing the present chapter, it should be stated
that painting in the fresco and encaustic styles, as also al
secco and al sgraffito, can be performed with casein paints.
The methods elaborated by the Diisseldorf artist, Fritz
Gerhardt, on the basis of prolonged investigation and chem-
ical progress, are founded on a special preparation of the
substratum and on the use of specially prepared colours.
These include the fresco colours, marble colours (containing
marble dust and casein), encaustic colours (prepared with
wax and resin), the spike-oil colours and the. universal
colours. The Gobelin colours (imitation Gobelins) and flag
colours, used for decorating flags, also belong to this class.

Finally, tempera painting can also be performed with
casein paints. According to Beissier, a colour of this kind
can be prepared by mixing—

Dry casein powder ; ; é j , , 7 parts.
Slaked lime . : ; , ; ; q arie’. tageee
Covering mass (chalk, ochre) ‘ ; : am St aren
Dextrin ‘ , : ‘ ; ; ; 5 Ree
Soap powder oAcgee ; : f ; , 8

”

and the necessary body colour.

THE TECHNICS. OF CASEIN PAINTING. 99

The wall pictures in the Hall of Fame (Ruhmeshalle) in
Berlin were painted in lime tempera by Professor Geselschap.
The medium, consisting of three parts by volume of fresh
casein and one part of lime, was prepared fresh every day
and ground along with the colours.

It is now generally admitted that paintings executed in
casein colours will remain unaltered in tone for years and
effectually resist atmospheric influences. They also exhibit
extraordinary brightness, a fine velvety sheen, and clearness
in the shadows. In contrast to other processes, it is possible
with casein colours to paint the same surface over and over
again, the effect gaining in beauty and solidity with each
application. Finally, the paintings can be executed on any
solid ground, and are easily cleaned when they become dirty.
On account of these advantages casein painting is gaining
ground, and a number of casein preparations for this pur-
pose are on the market, though they cannot be discussed
within the limits of the present work. In this connection a
thoroughly scientific investigation of casein painting—on the
same lines as that which has already been made in respect of
oil and mineral paints—is highly desirable.

The Value of Casein Paint.i—Though it has long been
known that casein combines with certain substances to form
agelutinant compounds, which become more or less insoluble
on exposure to air, and though it has been known that casein
has been detected in old paintings, many of a decorative
nature, yet it is only within the last fifty years or so that
any extensive use has been made of it for this purpose.

That an addition of milk to limewashes greatly increases
their durability has long been known, and in fact such a ~
mixture constitutes the first casein paint, the casein of the
milk forming with the caustic a compound which is the basis

1 From a paper read by H. Clucas, Toronto, at the 1914 Convention of the
Master House Painters and Decorators of Eastern Canada.

— 100 CASEIN.

of all such paints. The casein is rendered soluble, a result
that can be produced, not merely with quicklime, but also
with various substances having an alkaline action.

These are met with in commerce in the form of paste or
liquid, containing the casein in a dissociated condition, and
in some cases, already mixed with other substances used in
paint, such as linseed oil, boiled oil, varnish, resin, or pet-
roleum, in order to produce special effects. Others, and
these the most important of all, are supplied in the form of
powder by the makers, and contain casein and alkali in the
dry state.

It is only when these paints are mixed with water to
make them fluid for use that the alkali is dissolved, and in
turn acts as a solvent on the casein.

Making this powder up into paint is a comparatively easy
matter, though a certain amount of care is necessary to
insure good results. The operation may be performed in
any vessel that is clean, and free from grease, in the following
manner :— |

Fifty parts of water are added by degrees to 100 parts of
the powder, with constant stirring, which is continued until
the mass is homogeneous and free from lumps. ‘The mass
is then covered with a thin layer of water and left for about
half an hour, after which it is again stirred, and more water
added until a workable paint is obtained, about the con-
sistency of oil paint. The paint should be used without
delay, hence it is desirable not to make up any more of the
paint than can be used the same day. A solid and clean
surface is essential to success, as the paint will adhere to
any solid surface, such as lime, plaster of Paris, cement
plaster, brick, stone, or wood, as well as canvas without any
preparation, all that is necessary is to clean the surface of
dust or dirt and begin painting at once. The paint dries very
quickly and as smooth as enamel, and in forty-eight hours can

THE TECHNICS OF CASEIN PAINTING. 101

be washed. On account of its elasticity it can be used as a
primer under paint, varnish, or enamel. If applied on a firm
substratum it will neither crack nor peel off; but the surface
must be free from old coatings of lime or kalsomine washes.
It has been found both in the United States and Canada
that the main reason why casein paints did not become
popular as quickly as they deserved, was the fact that any old
kalsomine coat or lime wash had to be washed off to the
very last degree, because if any of the old washes, even to
the eighth of an inch, were left around the window frames
or door posts, and was covered over with casein paint, the
strong binders in the latter pulled off the weaker under coat
and caused a ragged appearance. Even the smallest part
would cause the paint to peel off even a little further than
was warranted by the under coat which was left (painters
will understand this action).

Further, all casein paints have the advantage of drying
quickly, and being easy to work without requiring special
preparation of the surface to be painted, except that already
mentioned. It dries without gloss on brick, stone, plaster,
wood, or canvas, without stopping up the pores of brick-
‘work. ‘These paints are soaked in cold water in order to
swell up the soluble binding constituents, salts, and similar
compounds, so that they may dissolve completely when
diluted further with cold water, and also a oe their
chemical functions.

In addition to the binding constituents the paint powders
of this kind contain mineral material, such as Paris white,
zinc oxide, lithopone, forming the bulk of the mass of the
given covering power, while the body colours are also present
to produce the desired shade of colour.

These pigments which are present in merely minute pro-
portions, in case of light colours, must be perfectly indifferent
to lime and alkali; a green, for instance, compounded with

102 CASEIN,

Prussian blue and chrome yellow cannot be used. The pig-
‘ments must be as pure as possible.

After a coat of casein paint has been applied, a second
chemical action takes place, by which, through exposure to
the air, the quicklime which has caused the casein to
become soluble, is changed into carbonate of lime and both
the casein and lime are then insoluble, the casein having
come back to its original form, as pure casein is not soluble
in water, hence the necessity of the lime to work it.

Notwithstanding their power of standing the weather,
cold water casein paints are porous, and do not prevent the
circulation of air. On account of their good qualities these
paints are in frequent use, both for outdoor and indoor work.

To the practical man there may be a doubt that cold
water casein paint is a cheap way of doing things, as com-
pared with white lead and oil, but expensive methods do not
always yield the best results. Casein paints have been and
still are much in evidence in European and American summer
resorts, and more especially on such work as factories, hos-
pitals, dormitories, garages, fences, boat houses, and many
summer cottages show evidence of its decorative and sanitary
purposes.

Cold water paints with casein binder and containing anti-
septics, have proved to be of greater durability than the bulk
of the ordinary water paints, on account of their resistance
to atmospheric influence and dampness, where the cost of oil
paint is prohibitive.

In concluding, I would mention one more of the many
purposes that casein water paints can be applied to and
prove itself invaluable to the present need of the trade, viz.,
on concrete and cement work. On a floor, a coating of fresh
cement was applied about three-eighths of an inch thick and
as soon as this was thoroughly dry (after three days) a coat
of white casein paint was applied. This coating was allowed

THE TECHNICS OF CASEIN PAINTING. 103

two days for the necessary chemical change to take place, as
described previously, and then a coat of ordinary floor paint
was applied and allowed to dry in the usual way. This floor
paint was found on careful inspection to be just as sound as
if it had been applied on a wood floor, or over a primer, and
did not crack or give way when loaded trucks were wheeled
over it.

CHAPTER VII.

CASHIN ADHESIVES AND PUTTIES.

THE employment of casein as ‘an adhesive substance is not
modern. It is only within the last few years that it has
received any marked attention, and has been placed on the
market under various names, such as casein glue, cold glue,
cold-water glue, caseogum, gluten, etc., these being not
merely suitable for industrial purposes, but also, mainly, for
replacing glue in the wood-working industries. Though
many of these preparations comply with all the requirements
of a glue substitute, and possess the additional advantages
of being inodorous and ready for immediate use without
previous soaking and heating, they have not become popular
to any very great extent. There is, however, very little
doubt that the prejudice against them will not continue
when their advantages are made fully known.

The raw material for these casein adhesives and putties
is the fat-free casein obtained from curdled milk reduced to
a liquid or pasty form by the aid of such chemical agents as
the alkaline earths, their salts, ammonia, tungstic salts and
water. The products thus formed are ready for use; but .
analogous products in the form of powder can be prepared
from casein that has been dried out of contact with air, then
ground and mixed with the solvent reagents in their dry
state. In general, casein glue ready for use, 2.¢., mixed with
water, has been more successful than the dry powder, but the
latter is probably more convenient when intended for distant

destinations.
(104)

CASEIN ADHESIVES AND PUTTIES. 105

The casein is prepared from milk in the usual manner, by
the addition of acids—acetic acid, tartaric acid, etc.—the
casein being accompanied by a certain unavoidable small
proportion of fat. Although weak acetic acid is usually
employed for precipitating casein from skim milk, it is not
the only acid used, as occasionally sulphuric or hydrochloric
acid may be used in place of it, this accounting to some
extent for the variations which are found in commercial
brands of the material. After precipitation the casein must
be neutralised before it can be treated further, for which
purpose it is steeped in a solution of lime (lime-water) until it
no longer reddens blue litmus paper. This treatment fur- —
nishes soluble calcium acetate, which must be washed out
before the casein can be converted into glue. For this reason
Bellamy recommends that the casein should be precipitated
by means of vegetable substances, whose coagulant properties
ate based on the presence of tannin, e.g., cutch, China bark,
oak bark and other barks, sumach, etc. Special success has
attended the use of wild-cherry bark (Prunus virginiana) for
this purpose. The resulting casein does not require neutral-
ising, and is easily worked up, besides being more uniform in
quality. At the same time, the quantity of the precipitant is
immaterial, since any excess remains in solution and there-
fore does not remain with the casein when this is boiled.
Whatever method of preparation is adopted, it is always
advisable to add to the casein a little sodium arsenate,
Na,HAsQ,, or some other salt of arsenic, since this increases
its adhesive power and forms a kind of chemical mordant.

Another method of preparing casein specially for use as
an adhesive is the following: Milk is left to stand in a
cool place and the cream carefully skimmed off, this being
repeated as long as any cream continues to rise, the milk
being heated after souring to make it curdle. To test
whether .all the casein has been precipitated by the lactic

106 CASEIN,

acid of the milk, a sample of the separated liquid is treated
with a little hydrochloric acid; if a precipitate is formed
there is still some casein in solution, and this should be
separated by the addition of 1 per cent. of hydrochloric acid,
without waiting any longer for it to curdle. The curd is next
pressed and washed with soft water until the washings are
free from all trace of acid. To remove the final particles of
fat the curd is boiled up with water and spread on a filter
cloth.

When dry the curd is pressed and dried, first at a
moderate temperature, then with an increased application of
heat, and finally in a partial vacuum, if necessary. In this
way it can be obtained either in the form of fine granules or
as a horny shrunken mass. In either case it will keep
indefinitely, but is liable to insect ravages, and especially to
those of certain larve.

Casein Glue.—According to the ‘ Revue des Produits
Chimiques,”’ ‘‘casein glue is prepared by dissolving fat-free
casein in a saturated solution of borax, the resulting concen-
trated solution having strong adhesive properties and finding
extensive employment as a substitute for glue and gum-
arabic”. The borax solution is prepared by dissolving 1
part of borax in 12 parts of cold water, the casein being then
added, little by little. 2

To prepare casein cement, curdled milk is triturated in a
mill and with successive additions of slaked lime until a
compact mass is formed. This must be used almost im-
mediately, since it hardens very quickly.

Casein dissolved by a solution of carbonate of potash or
soda also forms an excellent cement. The most suitable pro-
portions for the mixture are 5 parts of powdered casein and
1 part of pulverised burnt lime, mixed together with sufficient
hot water to make a thin paste. Casein for cement may also
be prepared from skim milk, by drying the latter in thin

CASEIN ADHESIVES AND PUT'TIES. 107

layers, reducing the product to powder and mixing it with
1 part of quicklime and enough water to form a paste.
Blood albumen may be used in place of casein for certain
purposes, its insolubility in water after exposure to a tem-
perature of 40° C. being utilised in the paper industry. A
weatherproof paint may be prepared by replacing casein by
finely divided glue, the colours being eround with size,
gelatine, or gum-arabic, and applied to the surface to be
coated. While the paint is still fresh it is treated with a
1 per cent. solution of bichromate of potash, which solidifies
the coating and enables it to stand washing. The same
result may also be obtained with a 20 per cent. solution of
chrome alum, rendered slightly alkaline with ammonia.

Casein Glue in Plates or Flakes—One hundred and fifty
parts of purified dry casein are mixed with 75 parts of a
solution of sodium tungstate and well stirred. The mass is
then thickened at a moderate temperature in a jacketed
enamelled pan (or on the water bath), 7.¢., 1s concentrated as
far as possible, and is then cast into moulds or poured out on
a sheet of glass or a marble slab. If moulded it can be
cut into flat slabs like glue and dried on trays; but in the
other case, according to the percentage of water present, it
forms a more or less solid mass, which readily dissolves in
hot water.

Bolder’s Liquid Casein Glue.—H. Bolder, of Charlotten-
burg, prepares a glue possessing the same adhesive properties
as ordinary joiner’s glue, but in a liquid form, which is ready
for use without warming and is capable of resisting moisture,
by treating dry casein with a dilute solution of borax, or
with sufficient ammonia to produce a faintly alkaline reaction.
This preparation may be used or mixed with liquid starch in
any proportion.

Crosspretsch’s Adhesive.—A mixture of casein, castor oil,
and linseed oil, thickened by heat, is treated with alum,

108 | CASEIN.

sugar-candy and dextrin, and heated until a homogeneous
mass is formed, which is then treated with water-glass.

Jeromin’s Casein Adhesiwe.—According to German patent
154,289, lime, sodium-silicate and casein are mixed together
and applied to the wood to be glued, left to dry and after-
wards heated, with application of pressure, to form a water-
proof joint. This method of mixing the three ingredients
direct has the disadvantage that the casein is not fully acted
upon; and it is found that the adhesive is more powerful
when the casein has been treated with lime water before
mixing it with the sodium silicate and lime.

The method of treating casein with lime or alkalies is not
new, as a process of this kind is described in German patent
116,355, though the purpose of the treatment in that instance
is a different one, namely, the production of a viscous solu-
tion of casein. With this object the casein is treated with
sufficient alkali to produce a faintly alkaline reaction, that is
to say, the amount of alkali added is in slight excess of that
necessary to neutralize the casein. This implies that the
casein is in the form of a solution and is no longer in the
gelatinous form, which solution, however, is incapable of
fulfilling’ the purpose for which it is intended, namely, that |
of an adhesive and filler. To overcome this drawback the
~ casein is reconverted into the colloidal state by means of
tannin, so that the final product is improved both as to its
adhesive and its filling power.’ Hence the method consists
first in preparing a non-adhesive solution and then con-
verting this into an adhesive by partial precipitation of the
casein.

On the other hand, Jeromin proposes to effect the same
result in a more direct manner. The dispersal and solution
of the casein by alkalies is in this case avoided, lime water
being used to make the casein swell up. In certain circum-
stances the whole of the lime can be added at once; but this

CASEIN ADHESIVES AND PUTTIES. 109.

is attended with the aforesaid drawback of unequal distribu-
tion of the casein, a contingency that is overcome in the
present case by the preliminary swelling of the casein in a
small quantity of lime water. It must be remarked, how-
ever, that in the subjoined recipe the quantity of lime water
mentioned does not contain enough lime to produce the
maximum effect, though it is sufficient to cause swelling
and thus prepare for the formation of a homogeneous mass
through the subsequent mixing and combination with the
lime which is subsequently added.

The method is performed as follows :—

Twelve and a half pounds of ground casein powder are
mixed with three times its weight of clear lime water, stirred
up in the same and left to settle for about forty-eight hours.
When the casein has absorbed the whole of the liquid, the
‘mass, weighing about 50 lb., is mixed with 24 lb. of lime and
25 lb. of water, the whole being kept well stirred for about
twenty minutes, after which 174 lb. of water-glass are stirred —
in. When this mass has stood for a while it may be further
diluted if necessary.

In this manner a very uniform and effective adhesive is
obtained, one far superior to that furnished by the process |
described in the German patent 60,156. |

The whole of the casein is acted upon, no unaltered
particles being left in the mass, as hitherto, such particles
being a source of weakness to the adhesive when placed
under heat and pressure, at the same time they diminish its
waterproof properties and, moreover, absorb moisture which
leads to putrefaction and decay. :

The use of lime for this purpose was also patented by
C. W. Luther (English patent 6104, 1892). —

Hall’s Casein Gluwe.—A powerful fireproof glue is ob-
tained, according to W. A. Hall (English patent 2949, 1903),
by mixing—

.110 CASEIN.

Dry casein . : : : : 50 to 60 parts by weight.
Sodium phosphate . ; ; 20 si ee
Sodium sulphite : ? é 10 5 x
Dry lime, slaked or burned ; 20 to 30 a _

In another of Hall’s recipes an adhesive is prepared by
modifying starch under the influence of heat, and stirring
this product with casein until the whole is nearly or quite
absorbed by the particles of casein, a solution of alkali being
added during stirring. By the intimate admixture of the
several ingredients a very useful adhesive is obtained.

Still another process consists in combining certain pro-
portions of casein, ammonia, and formaldehyde to form a
mass suitable for sizing paper, straw, etc.

In a patent granted to W. A. Hall, Assignor to the
Casein Company of America (U.S. patent 758,064, April 26,
1904), a mixture is made by incorporating a solution of
“modified” starch with casein and adding an alkali and
other ingredients during the process.

Waterproof Glue.—A waterproof glue or putty is obtained
by mixing an albuminous substance such as casein, albumen,
etc., with a caustic alkali (potash, soda or lime) or a carbonate,
silicate, borate or phosphate of soda or potash. The inventor’
states that when an excess of alkali is present the product
soon becomes insoluble in water at the ordinary temperature.
On the other hand, when the albuminous substance is in
excess the conversion proceeds slowly, but is accelerated by
heat. In using the latter preparation, the surfaces to be
joined are coated with the mixture, left to dry, and then
pressed together between hot rollers. Inert substances may
be added to the mixture.

Liquid Casein Glue.—To prepare a stable casein glue,
which will dry or set immediately and then resists moisture
and the influence of weather, 10 parts by weight of fresh
curd are mixed with 6 parts of water to a thick cream,

CASEIN ADHESIVES AND PUTTIES. TEE

warmed to 40° C. and more water added with a few drops of
ammonia, the liquid being allowed to stand till the casein is
fully precipitated. This furnishes pure casein, and the whey
can be eliminated by draining, pressure, or centrifugalising.
The resulting casein is washed by spreading it out on a
stretched cloth and pouring water over it.

The product is next mixed with ? to 1 part by weight of
strong ammonia solution in a pan and heated to 30° to
40° C., whereby it is converted into a liquid glue, which can
be diluted with about 80 per cent. of water and preserved by
an addition of carbolic acid or thymol.

To make a quick-setting joint with this preparation, it is
laid on with a brush, and left to dry, the surfaces being after-
wards brushed over with milk (or thin cream) of lime and

pressed together. The calcium of the milk of lime combines
in the joint with the casein of the glue, ammonia being |
liberated, the resulting calcium complex fixing the surfaces
so tightly that the joined article can be worked five minutes
afterwards.

The ammonia can, of course, be replaced by caustic
potash, caustic soda, or any other alkali, but the presence
of such alkalies renders the glue more sensitive to moisture.

Powdered Casein Glue.—Dried, purified casein, 15 to 20
parts by weight, is ground to fine meal in a pulveriser, and
then incorporated, in a sifting and mixing machine, with 1 to
4 parts of ground borax or 2 to 8 parts of sodium bicarbonate,
great care being bestowed on proper mixing.

Casein and Borax Glue.—This is a solution of casein in a
saturated solution of borax. It has a transparent, gelatinous
appearance, and when dried forms a yellowish-white, some-
what brittle mass, which is readily soluble in water, has high
adhesive properties and is suitable for cabinetmakers’ use.
It is prepared by setting milk to curdle in a warm place, the
completeness of the operation being tested with hydrochloric

112 | CASEIN.

acid, 1 per cent. of which is added to the milk if the test
indicates that casein still remains in solution. The purifica-
tion and drying of the casein are performed in the manner
already described at the commencement of the present
chapter. For use, the necessary quantity is placed in a
suitable vessel and mixed with levigated chalk, slaked lime, —
water-glass, and borax solution, an excellent adhesive being
thus obtained.

According to another report, this product is prepared as.
follows: Milk is heated with a little tartaric acid, or when
large quantities are to be produced, is curdled in the ordinary
way as for cheese-making. The resulting curd, in a still
moist condition, is sprinkled with a solution of 6 parts of
borax in 100 parts of water, and gently warmed and stirred,
the casein being. thereby dissolved. The clear solution is a_
strong adhesive, cheap and durable, and can be used to
replace gum-arabic in all cases where dextrin would be
unsuitable.

Casein for Mending Glass, China, etc.—Take one quart
of milk and stir into it 120 grains tartaric acid, gently
heating until it coagulates. |

Drain off the casein and dissolve it in a 6 per cent.
warmed borax solution, 7.¢., just sufficient to liquefy.

Solid Casein Adhesive.—The mass, consisting of a mix-
ture of alkali tannate, casein, and water, is said to possess
good adhesive properties. In the dried state it forms a
somewhat hard and rather elastic mass, which is insoluble in
_ water and various other liquids. It is prepared by pouring a
cold or warm solution of tannic acid (bark extract) into
a solution of milk of lime until precipitation ceases and
the filtrate has an alkaline reaction. The precipitate is
separated, and is dried at the ordinary temperature in a
current of air. This calcium tannate is powdered and mixed
with lime, unless an excess of this base is present already,

CASEIN ADHESIVES AND PUTTIES. 113

the whole being next ground along with casein powder, sifted
and stirred up with a sufficient quantity of water. According
to the desired character and properties of the finished pro-
duct, from 1 to 10 parts of casein are taken to each part of
tannate. Casein is not precipitated on adding water, but the
mixture forms a strongly adhesive mucilage which, when
dry, becomes hard, tough, elastic, and insoluble in water,
petroleum, carbon disulphide, and other liquids.

Casein Glue for Cardboard Boxes.—45 parts of dry casein
powder are dissolved by degrees in 64 parts of water with
continued stirring, 1 part of borax and rather more than 1
part of strong ammonia being added to the mixture, which
is next heated nearly to boiling for some time, the mass
being still kept stirred, and finally cooled. If the glue is too
thick, it may be thinned with a little ammonia. A good
casein glue can also be prepared from casein powder,
magnesium chloride, and gelatinised starch.

Casein Solution.—A preparation, patented by the Casein
Company of America, is made by precipitating casein with
hydrochloric acid, and dissolving 1 part of the precipitate
in 1 to 3 parts of water with an addition of 0:1 to 0°12 part of
trisodium phosphate. |

A solution of casein which may be useful for certain
purposes may be prepared by dissolving the albuminoid in
alcohol by the aid of an alkali hydroxide (soda or potash),
neutralising the alkali with an acid and then adding formal-
dehyde (H. V. Dunham, Assignor to the Casein Company,
America, U.S. patent 821,620, May 29, 1906). |

Joining Casein Plates—A. Scheel (German patent
293,510). .The plates to be joined are coated while still
moist and unhardened, with an intermediate layer of moist-
ened casein powder, the whole being then warmed under
heavy pressure, which renders the intermediate layer plastic

and binding.
8

114 | CASEIN.

Soluble Casein Compound.—C. Revis, E. R. Bolton, and
W. N. Bacon, London (English patent 24,662, November 6,
1911), have taken out a patent for a casein compound formed
by mixing together 10 lb. of borax and 300 to 500 Ib. of wet
casein (curd), containing 25 to 30 per cent. of dry matter.
The product forms a homogeneous liquid which, when
sprayed by an atomiser into a chamber heated to a tem-
perature much higher than that of boiling water, falls to the
floor in the form of an extremely fine and light powder,
which readily dissolves in water to form a mucilage. The
proportions given yield about 100 lb. of powder, containing
approximately 10 per cent. of borax.

Renken’s Method of Using Glue.—One side of the article
to be glued is treated with formaldehyde, the other coated —
with casein putty, and the two pressed together. Bottle
labels and the like are moistened with formaldehyde, dried
and coated with casein glue.

Glue Powder.—To prepare glue powder, casein is mixed
with powdered slaked lime in suitable proportions, the
mixture being stirred up with water for use. A very good
cement or binder is obtained by mixing dry casein with
levigated chalk, powdered slaked lime, and a solution of
sodium silicate or borax. .

Casein Glue.—A. Bernstein (French patent 370,940, 1906)
prepares a substance with the properties of glue by mixing
casein with metallic silicates in the colloidal state. With
this object, the casein, either in skimmed milk or after
separation therefrom, is dissolved in alkalies or alkali salts in
the usual manner, and is then mixed with water-glass and
some metallic compound with which the latter will react
such as calcium chloride, barium chloride, or magnesium
chloride in aqueous solution. The casein combines with the
metal of the chloride, while double decomposition is set up
between the chloride and the water-glass, forming alkali

CASEIN ADHESIVES AND PUTTIES. 115

chloride and the silicate of the other metal. This product
(e.g., for instance, magnesium silicate) is insoluble, and would
be precipitated in the absence of the casein, but in presence
of that substance it assumes the colloidal form, similar to
that of the casein solution, the mixture of the two augment-
ing the adhesive properties of the casein. The following
proportions of the ingredients may be regarded as typical:
100 parts of casein are mixed with 600 of water and dissolved
by the addition of 12 parts of carbonate of soda. ‘To this
solution are added 100 parts of a 10 per cent. solution of
magnesium chloride and 80 parts of sodium silicate or potas-
sium silicate, the whole being stirred continuously. The
dried product swells up like ordinary glue in cold water, and
dissolves in hot water.

A mixture of casein, rosin, and alkali was patented as a
cement by C. and A. Bernstein (German patent 270,200,
19138).

C. Wittkowsky also patented the use of sodium silicate
for this purpose (English patent 9070, 1905).

Casein Glue for Match-making.—Casein forms a good
substitute for glue or dextrin in match-making, for the
following reasons: It can be dissolved without heat, is
neither hygroscopic nor inflammable, and can also be made
waterproof by suitable treatment.

The preparation of the solution is simplified by using
soda casein or water-soluble casein instead of the variety
soluble in alkali. Water is heated to near boiling (190° F.),
and the casein powder is shaken in and stirred.

Lehner’s Casein Putties.—1. Fresh curd is boiled with
water until it has become a ropy mass, and slaked lime and
_ finely sifted wood ashes are stirred into the solution. The
proportions are :—

116 CASEIN.

Curd. ‘ : ; , ; : : . 100 parts.
Water 2.00 3 s ; é : : ; a ee
Slaked lime . ; ; 4 F : , aah), are
Wood ashes . : : ; 4 ; tare

2. Another putty, suitable for stopping large holes in
masonry or for pointing joints in brickwork, is compounded
of :—_ :

Casein . ; ‘ , : : : ; . 12 parts.
Slaked lime . ; : ae SRS : ‘ Rotor, 9 Rare
Sea sand ; ’ ; ‘ ; ; ; 5 ED Be

3. Casein Bind for Meerschawm.—Casein is dissolved in
alkali silicate, stirred quickly with finely-powdered calcined
magnesia and used at once, since it very soon hardens. If
meerschaum powder be added along with the magnesia, the
resulting mass closely resembles real meerschaum, and can be
used for making a substitute for the same. The meerschaum
powder is obtained by pulverising and sifting the waste
turnings and shavings of real meerschaum.

4. Casein Putty with Good Keeping Properties.—

Casein . ; : ; : ; : , . 200 parts.
Quick-lime . Ae athe : ; 40 ,,
Camphor. ; ; ’ 2 ’ : : : eePe

These ingredients are powdered separately, intimately mixed,
and packed in tightly closed glass vessels. For use, the
powder is stirred up quickly with the necessary quantity of
water and used at once.

5. Casein Cement for Porcelain.—Casein dissolves readily
in alkali silicate, the solution forming one of the best possible
cements for porcelain. It is prepared by shaking up 1 part
of fresh casein with 3 parts of water-glass in a bottle until
dissolved.

6. Casein Cement for Glass.—

“Skim-milk cheese. ; ; ; ; . 100 parts.

Water . : ; 4 4 ‘ y P rari 9. | Reartaess
Slaked lime . ; ; F ‘ < 3: ot SIO: hay

CASEIN ADHESIVES AND PUTTIES. 117

The cheese is separated from the rind, cut up into small
pieces, and rubbed down with water until a ropy, uniform
mass is produced, into which the slaked lime is stirred as
quickly as possible, the mass being used as soon as made.
It will not only cement glass firmly to glass, but can also be
used for fastening metal on glass, porcelain, and meerschaum
(pipe mounts). :
7. Casein Cement for Metals.—

Levigated quartz sand . ‘ ‘ ; : . 10 parts
Casein . ‘ ; , F ‘ ‘ ; 3 8-55

mixed with sufficient water to make a cream.

8. Casein and Borax Cement.—(a) Ten parts of casein
and 5 of borax are stirred with water to a thick milk, which
is used as glue. The mixture may also be used as an adhesive
for the labels of wine bottles, since it does not. become mouldy
or loosen in damp cellars.

(b) If the above cement be coated over several times with
gallnut extract when dry, it becomes waterproof, owing to the
formation of an insoluble compound between the casein and
the tannin.

Very strong waterproof fabrics, similar to those treated
with rubber solution, can be obtained by dipping closely-
woven cloth in a solution of casein and borax, allowing it
to dry, and then dipping it in a solution of gallnuts.

(c) Borax is boiled in water, and the cold solution is
poured over freshly precipitated casein, which it thereby
dissolves to a clear, thick, and strongly adhesive mass that
will keep indefinitely without decomposing.

This preparation applied to paper, leather, linen, or cotton
cloth forms a handsome glossy coating, and on this account
it is largely used as a varnish for cardboard boxes or leather
fancy goods. |

9. Casein and Water-glass Cement for Glass and Porce-
lain.—Casein, 10 parts, and water-glass, 60 parts, are mixed

118 CASEIN.

together. It is applied as quickly as possible, the cemented
articles being exposed to the air to dry.

10. Casein-Soda Cement.—Casein is precipitated from
milk with vinegar,-then washed and redissolved in a minimum
quantity of caustic soda solution, the prparuen being stored
in well-closed bottles.

Washable Cement for Deal Boards.—

Casein . ; 4 : : , Mae . 1802s,
Water . ; ; ; : : ; : : 7 pints.
Ammonia . : : ; : ; : ; eee
Quick-lime . : ; , ; : ; ' 9 ozs.

Wenk’s Casein Cement.—The casein is not used direct,
but is first treated, so that after the addition of some colloidal
substance with which it forms a complex (¢.g., tannin), it
acquires superior properties to those of cements prepared in
the usual way. The casein is rendered slightly alkaline with
soda or potash, and then heated for about twenty-four hours
at a temperature of about 140° F. It is next mixed with
lime or water-glass, and finally with some material containing
tannin, in order to ensure more rapid gelatination. The best
results are obtained when the casein has been prepared at
the above-named temperature; otherwise, it behaves less
favourably. The tannin solutions to use are preferably
about 1 per cent. of gallic acid, cutch, quercitannic acid, or
similar substances. The slaked lime, water-glass, etc., which
may be used in varyirig proportions, furnish the requisite in-
organic solvents for bringing about the more intimate com-
bination of the two colloids. The finished preparation may
be used for gluing wood in the ordinary way.

Casein and Lime Cement.—The rind is removed from
old, skim-milk cheese, and the mass is rubbed with water
and warmed until it furnishes a viscid mass like honey.
This mixture is next incorporated to a plastic mass with a_

‘CASEIN ADHESIVES AND PUTTIES. 1i9

sufficient amount of powdered, slaked lime, in a warm
mortar. An alternative method is to take skim-milk curd,
press out the whey, and mix the rest with lime as in the
previous example. The cement must be used at once as it
soon hardens. The curd will not take up more than one-
fourth its own weight of lime. If larger quantities are
needed, a little fine sand or brickdust, previously made up
into a paste with the lime and a little water, may be used to
replace part of the curd. When the cement is to be used
in very {ne joints, it is preferable to employ a solution of
carbonate of potash as the solvent, and evaporate any super-
fluous water, or mix the fresh curd with the dry salt. This
cement is particularly suitable for mending glass or porcelain.

“Pitch Barm.’—This is a cement capable of numerous
applications, and is made by mixing fresh curd with water-
glass and powdered caustic lime. The curd must be well
pressed to expel the water and is then incorporated with the
water-glass, the lime being stirred in so as to form a paste
just before use. It hardens quickly.

Casein Stopping.—This is used for stopping cracks and
joints in wood, stone, and brickwork, and is prepared by
mixing 14 parts of water-soluble casein, 8 of levigated chalk,
2 of calcined magnesia, and 2 parts of fine sawdust.’ Just
before use the mass is stirred to a pulp with water. It
penetrates the cracks, hardens quickly, smoothens nicely and
does not shrink.

Casein Cement for Stone.—Fresh curd, pressed to expel
the whey, is kneaded in warm water with about one-fourth
its weight of powdered slaked lime, to form a soft, plastic
mass which must be used immediately as it hardens quickly,
To give the cement more body—which is desirable for use
with stone—the lime should have been mixed beforehand
with about its own weight of fine sand or brickdust, the
mass being made up to a stiff mortar with water before

: : 120 CASEIN.

adding the curd. The surfaces to be cemented must be
well moistened. |

Another excellent cement for ne purpose, which sets
slowly, becomes very hard, and answers admirably for. pro-
tecting joints in stonework from water, alkalies, etc., consists
of fine cement mixed to a stiff paste with sree its own
weight of fine brickdust, and with moistened curd.

A good cement for wood is made of equal quantities of
powdered quick-lime, dry curd, and albumen, mixed together
by stirring. -

Insoluble Casein.—Morin makes an insoluble casein by
treating the commercial article, preferably in the form of
powder, with trioxymethylene, previously dissolved or sus-
pended in water. The mixture is then heated to about 60° C.,
the casein softening to a pasty mass which can be shaped or
moulded as desired. Under the influence of the small quan-
tity of water which remains in the mass after pressing, the
trioxymethylene is decomposed into formaldehyde, which
substance, being in intimate association with the casein,
renders the latter insoluble. This reaction proceeds slowly,
so that no bubbles are formed. The mass may be incorpor-
ated with emery or the like, to form grindstones, or may be
coloured in any desired way.

CHAPTER VIII.
THE PREPARATION OF PLASTIC MASSES FROM CASEIN.

CASEIN, like all substances possessing strong adhesive
properties, is specially adapted for the preparation of
plastic masses, which can be moulded, either alone in the
form of paste or'a more or less dry powder, or in admixture
with organic substances like sawdust, wood meal, paper, etc.,
which masses can be readily moulded and set hard when dry.
Casein mixed with lime or other alkaline material can be
converted, by the addition of a little water, into a plastic
mass which can be stained any colour, and dries, though very
gradually, in the air to a transparent solid as hard as bone.
In this condition it can be turned in the lathe or worked
with ordinary cutting or carving tools. When plastic casein
is mixed with other substances, such as organic or finely
powdered inorganic materials, the resulting products dry
much more rapidly, especially under the influence of warmth.
Care must, however, be taken in the drying process—which
should be slow—owing to the fact that all masses containing
much water shrink and easily crack during the process. _
The adhesive properties of casein, which have been
adverted to in a previous chapter, have already met with
extensive industrial“ application. Great success has also
attended its application to render celluloid uninflammable ;
and special mention will be made later of the most recent
celluloid substitute—galalith. This is an excellent example

of how modern ingenuity has enabled a raw material, hitherto
(121)

4,

122 - CASEIN.

of but slight use technically, to become of considerable
industrial importance.
Imitation Ivory.—Milk curd, partly or wholly freed from

its aqueous and fatty constituents and broken up into small

lumps, is kneaded for about fifteen minutes in water which
is nearly boiling. This treatment causes the separation of
fatty or granular impurities, leaving the casein in an almost
perfectly pure ‘state as a tough sticky mass. Care must be
taken, however, not to prolong the kneading beyond the
proper stage, or the curd will be too soft and weak. The
product may after this treatment be pressed out into flat
cakes or blocks of any desired shape.

The casein prepared in this way can be mixed with pig-
ments or other materials, such as ivory dust, ground bone or
ground porcelain, according to the character of the material
it is intended to imitate. The prepared casein is stirred for
about ten minutes in hot water, which causes it to soften;
and it can then be incorporated with the necessary colouring
matter or other ingredients, and the resulting plastic mass
cast into moulds.

The curd, freed from whey, may also be kneaded in its
own water of saturation, little more being added if necessary,
at a temperature approaching the boiling-point. For this
purpose, the curd should be broken into small pieces, this
treatment facilitating the removal of fatty and other ex-
traneous matter. By this means, the curd can be manipulated
at a lower temperature and far more cheaply than by the
first-named method, and also furnishes a tougher quality of
casein. The colouring matters or other admixtures can be
incorporated as soon as the fat has been washed out and the
mass has been worked, thus obviating any special mixing
process. The temperature to which the curd containing the
water of saturation is exposed, should be about 120° to 175°
F., according to the character of the curd. It is then worked

THE PREPARATION OF PLASTIC MASSES FROM CASEIN. 123

or kneaded for about fifteen minutes, with or without the
addition of a little more water, according to requirements,
the water of saturation usually sufficing to render the mass
plastic. The product being a tough, sticky mass which can
be pressed into flat cakes or any other suitable shape. The
preparation is specially adapted for various decorative or
useful articles; the further treatment consisting in rolling,
pressing, moulding, or any other suitable process.

Lilienthal’s Plastic Mass.—The ingredients of this
preparation consist of caustic strontia, powdered marble
or limestone, and casein, the following proportions being
recommended: powdered marble or limestone, 3 to 4 parts;
caustic strontia, 1 part; and a quantity of pressed casein
equal to about one-sixth of the other two substances com-
bined. The ingredients are mixed together in any suitable
mixing or stirring machine, the strontia and casein combining
to form a very firm binder which imparts great hardness and
strength to the articles made from the mixture. The mass
is formed into the desired shape by moulding under heavy
pressure.

Jung, Brecher & Kittel’s Insulating Preparation.—This
preparation is made of a mixture of casein and vegetable
oils, which latter may be either in a natural state or sul-
phonated. The low price of rape oil, linseed oil, and castor
oil renders them specially suitable for the purpose. The casein
may be prepared in any suitable way, and is used either in
the state of dry powder, the pressed damp condition, or dis-
solved in alkali, borax, or other solvent. In the two former
cases the oil is kneaded with it until a homogeneous, gelatinous
mass is formed, but when dissolved casein is used the liquid
is evaporated until a kneadable mass is formed, which is then
mixed with the oil.

The preparation may be worked up alone or in admixture
with caoutchouc solution or rosin, to form a homogeneous

124 CASEIN.

mass, and when rosin is used the product may serve as a
rubber substitute. It may be further incorporated with other
ingredients used in the rubber industry, such as litharge,
chalk, lime, pitch, or other colouring material. The final
product is employed in the manufacture of imitation rubber
goods by moulding and drying, and it may also be vulcanised ©
with sulphur, irrespective of whether raw or sulphonated oil
has been used.

Anti-Radiation and Anti-Corrosive Composition.—To
prevent loss of heat by radiation from steam pipes, these
may be coated with one or two layers of a mixture of 10
parts of casein and 25 parts of Portland cement and water-
glass, the whole being stirred together and thinned to a work-
able consistency with water. Asbestos may also form part of
the composition, or the pipes may be wrapped with asbestos
rope before the second coating has dried. On account of its
constitution and consistency, the composition may be re-
garded as a plastic mass rather than as a paint. _

_Dickmann’s Covering for Floors and Waills.—In this
invention paper, peat, or other vegetable or animal fibres, or
cellulose, asbestos and the like, may be rolled into sheets or
converted into a pulp in admixture with oxidised linseed oil,
metallic oxides, casein dissolved in ammonia, alum, iron sul-
phate, water-glass, resins, paraffin, wax, salt, glue, gelatine,
potassium chromate, rubber, flour, cuprammonium hydroxide,
formaldehyde, or mixtures of two or more of these substances.
The under side of the sheets may be fitted with projections;
or holes or hollow cavities or cells can be arranged inside the
sheet. ‘These spaces may be filled with peat, sawdust, rubber,
cork, linoleum, leather, or other sound-deadening material
that is elastic and non-conducting ; or compressed-air cham-
bers may be provided within the material. Wall coverings
of this kind may be decorated in any suitable way on the
outer surface.

THE PREPARATION OF PLASTIC MASSES FROM CASEIN. 125

Imitation Linoleum.—Albumen, 50 to 80 parts; casein,
50; ground cork or leather scraps, 20 to 40; flowers of
sulphur, 2 to 4; and caustic soda lye, 15 to 16 parts, are
intimately mixed together to form a mass which can be
rolled into strips. ‘The main components are alkali albumin-
ate and alkali caseate.

Imitation Leather.—Imitation leather may be produced
from casein by preparing a felted mass of vegetable fibres
and animal wool; this felt being impregnated with a mixture
of linseed oil, rosin, turpentine, wax, glycerine, glue, and
casein, together with small quantities of borax and potassium
bichromate, the liquid having been gently warmed before
use. After impregnation the felt is partly dried, and is then
treated with a solution of aluminium acetate, followed by
completing the drying process, cleaning and pressing be-
tween warm rollers. The product forms a very good imita-
tion of leather.

Imitation Bone.—Clean, white bones or bone chippings
are finely ground and mixed to a stiff paste with casein solu-
tion, which is then pressed in iron moulds and dried,at 130°
to 140° F. The mass is next roughly ground, moistened and
dried under heavy pressure and at a high temperature in.
moulds. Steam presses are used, the size of the press and
the working pressure varying with the dimensions of the
plates to be produced; two men are required, one to look
after the engine, the other in charge of the press. The
metal moulds in which the plates are formed are heated in
the press by means of the bed and pressing head, which are
traversed by channels containing gas jets.

Artificial Horn, etc., from Casein.—C. Pozzi and A.
Tondell (French patent 386,011, January 7, 1908) propose
to treat skim milk with rennet at a blood heat, leaving it to
stand ten to fifteen minutes when curdled, and expelling the
whey by the aid of beaters. After standing half an hour the

126 CASEIN...

whey is poured off and the curd drained on a sloping -table,
washed with water, squeezed to remove fat and sugar, and
bleached by washing with very weak sulphuric acid, hydro-
chloric acid, or other suitable agent, the surplus acid being
removed by washing with lukewarm water. The next step
is to heat the curd in a jacketed pan with twice its own
weight of water, containing sufficient lactic acid to replace
that naturally present in the whey, the temperature being
slowly raised to 35° to 40° C. to facilitate the ripening of the
paste. The desired stage will have been reached (in fifteen
to eighteen hours) when a sample, plunged into boiling water,
changes to a tough, springy mass, whereupon the tempera-
ture of the water jacket is raised to 70° to 75° C., and the
contents of the pan are stirred with: a spatula until they
unite to a compact, tenacious, and fibrous mass. This is
taken out of the pan and kneaded and rolled, at a constant
temperature of 50° to 55° C., until all the water is removed.
After cooling to 15° to 22° C., the mass is chopped small in a
machine and transferred to press moulds or frames, in which
it is subjected to pressure for twelve to fourteen hours. The
pressed sheets are then stained to resemble horn, lvory,
mother-of-pearl, etc., either plain or in fancy patterns, after
which treatment they are spread out, one above another, on
thick sheets of cloth in an iron frame, and placed in an
autoclave charged with water containing glycerine and for-
maldehyde in different proportions, according to whether the
product is desired to be more or less waterproof, flexible,
or hard, the operation of endosmosis being accelerated by
pumping air into the closed vessel until the pressure attains |
about two atmospheres. Here the sheets remain for about
ten hours, and, after being dried, are ready for use. :

By regulating the gas flames the heating can be adjusted
and kept uniform ; on no account should the metal be heated
to redness. The temperature is regulated by the melting-

THE PREPARATION OF PLASTIC MASSES FROM CASEIN. 127

point of metallic alloys. The mould and cover are placed
empty in the press and heated; and the interior of the
mould being carefully greased or oiled, the necessary
quantity of material is inserted, the cover put on and the
pressure gradually applied. The press attendant requires
to be skilled, in order to judge correctly when to stop press-
ing and take the plate out of the mould. When sufficiently
pressed, the plates are removed into a moderately warm room
to complete the drying.

The finished mass is very hard and tough; so much so
that it will not break when thrown down on a stone floor.
It can be turned in the lathe, like real bone, takes a beautiful
polish, and is capable of numerous applications.

According to the ‘‘ Eborit. Ges. m. b. H.” (German patent
191,125, December 16, 1902), casein treated with dilute hydro-
chloric acid forms a gelatinous plastic mass which may be
used for moulding purposes.

Plastic Mass of Keratin and Casein.—Substances con-
taining keratin are dissolved in alkalies or alkali sulphides,
together with casein, colouring matters, and the like. The
keratin is thrown down from the solution by mineral acids
and tannic acid, and the resulting mass is put into moulds,
pressed and dried.

Insulating Mass.—This mass consists of a mixture of
skim-milk casein and a solution of resins (preferably mastic
or sandarach, with a little amber) in alcohol or turps (German
patent 106,466).

Plastic Casein Masses.—Dissolved casein is mixed with
a solution of resin, the mixture being incorporated with
vegetable or mineral ingredients, and treated with for-
malin to coagulate the casein. This mass, whilst still in
a plastic state, may be spread on a network of wire,
rushes, or straw, so as to obtain a light, unbreakable, in-
sulating material.

128 CASEIN.

A. Bartels, Harburg, Germany (French patent 420,543,
September 19, 1910), also claimed the production of horn-like
masses by heating with water under pressure and then
hardening with formaldehyde. A further patent granted to
Bartels (U.S. patent 1,211,526, January 9, 197), claims the
use of a solution of hexamethylene tetramine and glycerine
in the production of horny substances.

-H. Morin (French patent 388,441, May 30, 1907), incor-
porates with the casein some trioxymethylene, which decom-
poses slowly with formation of formaldehyde, the casein being
thus hardened, rendered insoluble, and also preserved from
decomposition. |

Substitutes for horn, ivory, and the like, are prepared,
according to W. Plinatus (French patent 465,048, November
18, 1913), by treating casein, or albumen, or derivatives of the
same, ¢.g., alkali-albuminates with the acid or neutral esters
of the higher alcohols or amino-fatty acids. By this treat-
ment the albuminous compound becomes hardened or coagu-
lated, and in this state may be mixed with other products to
form plastic masses which may resemble horn, ivory, etc.,
according to the nature of the latter.

Plastic masses are also formed by mixing together albu-
minous substances in alkaline or other solution, casein,
sodium carbonate, rosin oil, gum, and glue. The product is
then moulded, dried, and afterwards steeped in formaldehyde.
“Soc. anon. franc. de Chim. Ind.” (French patent: 425,204,
March 30, 1910).

The “Soc. anon. L’Oyonnaxienne’’ (French patent
472,192) claim the use of mixtures of casein with amines,
amides, and their derivatives, as, for instance, aniline, ace-
tanilide, etc., for the formation of plastic masses.

In the manufacture of a thermoplastic material from
casein, B. B. Goldsmith, New York (U.S. patent 840,931,
January 8, 1905; English patent 14,098, June 18, 1907),

THE PREPARATION OF PLASTIC MASSES FROM CASEIN. 129

- mixes with it 8-naphthol and submits the material to heat
and pressure. ,
According to another process, milk is warmed to about
140° F., treated with a considerable addition of borax, and —
heated further to about 190° F. in presence of barium
chloride or other mineral precipitant of casein. The washed
precipitate is pressed and ground with an addition of acetic
acid, soda or other solvent, and the resulting mass is put
into a steam-heated press. The product is similar to bone or
celluloid. |
Manufacture of Transparent Horn-like Casein Masses.—
No. 13,203 of 1916.—Dr. A. Bartels, of No. 102 Buxtehuder-

on

Fia. 15. Fia. 16.

strasse, Harburg an der Elbe, Germany, claims: (1) A
process for the manufacture of transparent horn-like casein
masses which consists in agitating dry commercial casein
with a fat solvent for a considerable time at a temperature
above that of the atmosphere, and after drying, treating the
product in the usual manner. (2) A process as claimed
according to claim 1, wherein alcohol or a mixture of alcohol
and benzol or benzine is employed as the fat solvent. (3) A ©
process as claimed in claim 1, wherein the dry commercial
casein is agitated in a rotating extracting vessel with a fat
solvent, the latter being renewed if required, whereupon,
after running off the extracting agent, the casein is heated in

the same rotating vessel in a vacuum with energetic motion
9

130 : CASEIN.

for the purpose of being dried, after which it is worked up
into artificial masses in the usual manner. (4) An apparatus
for the carrying out of the process specified in claims 1-3,
having a strainer drum which serves to hold the material to
be treated and which is rotatably mounted in a liquid-con-
taining cylinder in such a manner that, as the strainer drum
rotates, the liquid solvent admitted into the cylinder is carried
up and distributed thoroughly over the whole material in
movement, characterised in this, that the liquid containing
cylinder is divided longitudinally, and that the upper part is
removable., (5) An apparatus as claimed in claim 4, wherein
the strainer drum is provided in its periphery with scooping
channels for the purpose of carrying up large quantities of the
liquid solvent in its rotation. (6) An apparatus as claimed in
claim 4, wherein the drum shaft is divided and provided with
a coupling so as to allow of lifting the strainer drum out of
the casing, and also wherein one wall of the drum is made
wholly or partly removable, or is adapted to be opened for the
purpose of charging and discharging the contents of the
drum.

Horny Casein Mass.—According to P. Horn, dried casein
is dissolved in dilute caustic potash, and heated along with a
quantity of sulphur at least equal to the amount of alkali
taken. The casein, potash, and sulphur are thereby dissolved
to a clear liquid, which is concentrated to the thickness of
syrup, moulded and dried, or made suitable for various
technical purposes by the addition of loading ingredients,
driers, or hardening preparations. For example, a very elastic
mass is obtained from the following proportions :— |

Water : ; j , : 200 parts by weight.
Casein ‘ ; ‘ ‘ . 100 _,, ”
Potash . ‘ ; : 5to10 ,, i
Sulphur. i ‘ ; . 10 to 30 _—"», "9

The elasticity increases with the proportion of sulphur

THE PREPARATION OF PLASTIC MASSES FROM CASEIN. 131

taken. The final product may be hardened by adding lead
hydroxide, zinc hydroxide, and potassium or sodium silicate,
whilst wood, cork, sand, or emery may be added to increase
the drying properties, or as fillers.

In another recipe, 100 parts of skim milk are treated with
about 4 part of acid, sulphuric, or hydrochloric. The pre-
cipitated casein is separated from the liquid, and set aside for
one to three days to ferment, whereupon it is pressed, and
dried at 140° F. The mass is powdered, and 70 parts of it
are mixed with 28 of bone meal, gypsum, kaolin, or graphite,
together with 2 parts of stearin, paraffin, wax, etc., and
colouring matter if necessary. The whole is made into a
pulp and warmed at 190° F., moulded and pressed, the
finished product being dusted over with calcined magnesia,
immersed in water for two days, and finally dried at 68° F.

' Production of Plastic Masses from Casein.—To obviate
the necessity for employing acids in the preparation of plastic
masses from casein, Kathe (English patent, 17,953, August 7,
1907) merely heats the casein with water to a high tempera-
ture, at which the former undergoes a change of character.
The amount of water the casein will absorb varies slightly
according to the degree of purity of the material itself, but is
independent of the quantity of water employed for heating.
Thus, if 1 part of casein be heated with 10 parts of water,
the resultant plastic mass is the same as if the proportions
were only two to one. The granular casein changes into a
coagulated, coherent mass, similar to caoutchouc, from which
all the water that is not chemically combined can be removed,
leaving a soft, uniform substance, which, on compression and
cooling, furnishes articles of considerable hardness, needing
only a few days’ drying. The casein may also be mixed with
the necessary amount of water, and heated in moulds with
_ superheated steam.
J. Kathe, Cologne, declares his invention as described in

182 CASEIN.

the following statement: In the production of plastic masses
from casein according to the German patent, 147,994, the
disadvantage arises that the plasticity of the casein cannot
be attained either by damping or by the use of great pressure
and heat, so that a process is claimed in which use is made
of small quantities of acids. The present invention consists
in that the use of chemicals is wholly abolished, and a mass
with greater plasticity is obtained by simply treating the
casein with water vapour whereby an agglomeration of the
casein takes place. The amount of water vapour absorbed
by the casein is dependent upon the purity of the casein.
By this treatment the granular casein is converted into
a rubber-like mass from which all the water, which has not
combined therewith, but is only mechanically enclosed, can
be removed. ‘There then remains a soft mass, which in this
condition is pressed producing fairly hard objects which
require only a few days wherein to dry. In order to render
the material less pervious to water, the pressed objects are
treated with formic aldehyde.

K. P. Boerma (German patent 241,887, January 16, 1910),
also uses water only for rendering the material workable ;
the casein after moistening, containing 20 to 42 per cent. of
water, is heated under high pressure whereby it is converted
into a homogeneous mass which can be moulded into any
form required.

Plastic Mass from Celluloid.—The inflammability of
celluloid can be diminished by the addition of incombustible
substances, of which casein is one; and this application
of casein has already been repeatedly advocated and em-
ployed.

According to H. V. Dunham, Assignor to the Casein
Company, New York (U.S. patent 748,709, January 5, 1904),
a product resembling celluloid can be obtained by mixing
solutions of casein and nitrocellulose in glacial acetic acid or

THE PREPARATION OF PLASTIC MASSES FROM CASEIN. 133 |

other known solvents, with camphor or the like material used
in the manufacture of celluloid.

To obtain a homogeneous compound of nitrocellulose |
and casein, Barnodai converts casein into a plastic mass by
means of an aqueous solution of borax or other casein
solvent, removes the excess of water, dips the product in
alcohol in order to displace a portion of the water absorbed
by the casein, eliminates the excess of liquid, and then in-
troduces into the mass a quantity of elastic nitrocellulose,
the whole being kneaded until homogeneous.

According to the Compagnie Frangaise 4 Celluloid, a
cheap substitute for celluloid is obtained by introducing
casein into the composition from which celluloid is prepared.
One hundred parts of casein are moistened with a solution
of 5 parts of urea in 50 parts of denatured alcohol, and
mixed, after forty-eight hours, with nitrocellulose and cam-
phor moistened with alcohol. After a further forty-eight
hours the mass is treated in the same way as celluloid paste,
with the subsequent addition of formaldehyde to render the
casein insoluble. :

Casein-Cellulose Composition.—A composition suitable
for many purposes forming also an excellent electrical in-
sulator and waterproof material when subjected to heavy
pressure, can be prepared from cellulose and an ammoniacal
solution of casein. If necessary the mass may be incor-
porated with repulped paper with or without the addition of
a mineral substance such as magnesia, talc, kieselguhr and
some body colour. The casein may be replaced by pressed
curd, and the waste paper by alkali cellulose (J. G. Jurgens
and H. Timpke, French patent 420,164, 1890). In the latter.
event, the alkali in the cellulose dissolves the casein, which
thereupon penetrates into the cellulose furnishing a homo-.
geneous: product which can be incorporated with vegetable
fibres or powdered mineral substances and coloured with

134 CASEIN.

_ pigments. The product may be made more impervious to
water by adding to it a solution of ferrous sulphate or copper
sulphate, or an alkaline solution of shellac, mixing the whole
well and pressing it in metal moulds. The finished articles
can be worked in the same way as wood.

/ Fireproof Cellulose Substitute—A hard, glossy fireproof
“ substance is obtained by the following recipe. A solution of
200 parts of casein in 50 parts of strong ammonia and 400 of
water is mixed with—

Quick-lime ; ; : ; : . ; 240 parts
Aluminium acetate . : . 3 ‘ f 150: & <5,
Mtge. Bre Se OEE one pia re 50: 4,
Gypsum . : ; . ; ; , RS

followed by 100 parts of linseed oil.

~The mass is kneaded until perfectly homogeneous, and
is then rolled into sheets of any desired thickness. ‘These
are dried and pressed in hot metal moulds, or else are re-
duced to powder, filled into moulds and exposed to heavy
pressure. The moulded articles are dipped into a bath of
10 parts of phosphoric acid in 100 of water, and are after-
wards dried, polished, and varnished with a solution of
shellac, consisting of 3 parts of shellac, 1 of borax, and 20
of boiling water.

According to another recipe, plastic articles of all kinds,
and especially decorations and ornaments of paper, can be
made to appear as though made of plaster of Paris, stamped
sheet metal, or carved wood. .T'wo press moulds are used :
one positive, the other negative, fitting accurately one into
the other. A few sheets of ordinary paper, previously
moistened, are laid in the negative mould and worked with
the finger tips so as to fill up all the depressions in the
mould. Casein glue is applied to each sheet before the next
is put in; and when a sufficient thickness has been attained
(14 to 15 pieces of ordinary packing paper are usually enough),

THE PREPARATION OF PLASTIC MASSES FROM CASEIN. 135

the positive mould is placed in position and the whole sub-
jected to heavy pressure in a press. By this means the wet
paper is forced into all the edges, projections, and depressions
of the negative mould, and when the former is taken out of
the mould it will be found that all the outlines and other
details of the negative mould have been sharply reproduced
on the surface. The paper is then dried, and at the same
time exposed to’ the action of formaldehyde vapour. Finally,
the ragged edges are trimmed, and the finished article can
be coloured or gilded as required.

Franquet's Celluloid Substitute.—Celluloid and xylonite,
both of which are used to make imitation tortoiseshell, ivory,
horn, etc., are expensive, and the casein products, such as
lactite and lactoite, are frequently brittle, or become so in
time. According to Franquet, however, the product obtained
by mixing casein with nitrocellulose and camphor, possesses
the same properties as celluloid, and is much cheaper. It is
flexible, very hard, without being brittle, and is impervious
to water; it can also be sawn, turned, filed, and carved.
When heated to 160° to 190° F. it becomes very plastic and
can be moulded.

To obtain a homogeneous compound of nitrocellulose and
casein, the latter is formed into a plastic mass with one of
its solvents, e.g., an aqueous solution of borax; the excess of
water is removed, the mass is dipped in alcohol, to extract a
portion of the water absorbed by the casein, the excess of
liquid is removed from the mass, and the latter is then
kneaded along with plastic nitrocellulose until homogeneous.

When camphor is used, 100 parts of nitrocellulose are
treated with 40 to 50 parts of camphor dissolved in 50 to 60
parts of 95 to 96 per cent. alcohol.. The casein is rendered
plastic in the following manner: The casein is immersed for
twenty-four to forty hours in a 5 per cent. aqueous solution
of borax, or other casein solvent, e.g., sodium carbonate. It

136. : CASEIN.

is next dried, dipped in alcohol, acetone, sulphuric ether, or
acetic acid, dried for several hours or pressed, and mixed
with the nitrocellulose. Another method is to steep the casein
for twenty-four to forty-eight hours in borax solution, or in
some other casein solvent containing 3 to 4 parts of alcohol
or other solvent of nitrocellulose. The casein and nitro-
cellulose products are afterwards rolled together for three
to four hours between rollers, and thus furnish a transparent
or translucent and perfectly homogeneous mass, which can
be drawn out into sheets 2 to 4 inches thick. These sheets
are pressed together, as in making celluloid, the block being
thereupon cut into plates of the desired thickness. Mineral
and other substances can be easily added to the mass.
According to an additional patent (February 23, 1902) casein
alkali compounds are added to nitrocellulose that has been
treated with alcoholic camphor, the mixture being then
treated in the same way as celluloid.

According to the master patent (German patent 138,783),
a mass resembling celluloid is obtained by adding casein to
ordinary celluloid; and pure casein may be replaced, for this
purpose, by a compound of casein with a metallic oxide. For
a transparent product, the casein-aluminium compound is the
most suitable adjunct ; the zinc or magnesium compounds for
a white product, and the corresponding compound of man-
ganese, iron, copper, or nickel for coloured articles. The
casein compound must be repeatedly and carefully washed,
from 1 to 5 per cent. of borax being added towards the end
of the process, to render the mass more plastic and facilitate
mixing with the other ingredients.

Plastic Mass with a Casein Basis.—Jannin claims for
the plastic mass prepared in the following manner that it will
replace celluloid and caoutchouc for many purposes, being
very solid, and at the same time easy to cut, saw, turn, and
work in various ways without splitting or cracking, besides

THE PREPARATION OF PLASTIC MASSES FROM CASEIN. 137

being uninflammable, a good electrical insulator, and capable
of resisting the action of chemical reagents. In principle,
the method consists in mixing casein with some fibrous
material like cotton or wool cut into short lengths, in order
to render the casein less brittle and enable it to be worked
without splitting, the proportion of fibrous material used
varying according to the degree of strength and translucency
or opacity desired. A certain quantity of oil or other fatty
matter, glycerine, etc., is also desirable, but not essential. The
following proportions may be regarded as typical: Water, 100
parts ; alkali, 5; fibrous material, 10 to 50; oil or fatty matter,
10; casein, 100; colour, quant. suff. The water and alkali
. are mixed, and the colouring matter incorporated. The finely
divided fibrous material is then stirred in; followed by the oil
and casein in succession, the mixture being stirred and heated
to dissolve the latter. The pasty mass is rolled to complete
the mixing and expel imprisoned air, after which it is moulded
into blocks, rolled into sheets or formed into any desired
shape. Formalin or other hardening agent may be added.

F. von Kagenek.(German patent 281,541, November 12,
1913) has patented a combination of casein and gelatin,
which is treated with sodium silicate to render it plastic, and
is then hardened by the addition of alum. This is stated to
be suitable as a substitute for celluloid.

In the process invented by L. Collardon (French patent
359,073, November 2, 1905), casein is incorporated with a
20 per cent. solution of viscose (cellulose thiocarbonate)
or other cellulose derivative, together with a solvent at a
temperature of 60°C. This forms a plastic mass which may
be moulded. Substances which decompose the viscose and
at the same time render the casein insoluble, and thus harden
the composition, may be at the same time added.

Galalith.—Galalith is the name applied to a plastic mass
which, in a variety of forms and colours, has found a large

138 CASEIN. |

number of practical applications. The method of preparation
is based on the production of a clear, non-milky casein, first
disclosed in the German patent 115,681, granted July 15,
1899, to Adolf Spitteler of Prien, Upper Bavaria.

The specification of this patent states that the cheap,
imperfectly purified, commercial varieties of casein furnish
turbid solutions, which in turn yield translucent, but not
transparent, solid products. True, according to Lundberg,
casein itself, when in the form of faintly alkaline solutions, is
soon transformed into alkali alouminate ; nevertheless, these
solutions will remain milky, both when heated and when
kept for several days, if impure casein has been used ; neither
can they be clarified by repeated filtration. If such solutions —
be precipitated, the substances causing the turbidity are
thrown down as well, the deposit when dried being opaque, in
_ thick layers.

It has been observed, however, that caustic alkalies pre-
cipitate these opaque substances, thus enabling clear solutions
of casein to be obtained.

Technical casein is mixed with 13 times its weight of
water, containing in solution 24 parts of Na,O per 100 of dry
-easein. This gives a uniform milky liquid, which when
treated with progressively increasing quantities of 5 per cent.
caustic soda furnishes the results expressed in the following
table. No further change is produced by even doubling the
quantity of caustic soda, though the addition of larger pro-
portions of 20 per cent. soda lye cause precipitation of a
sodium casein product, which redissolves on dilution with
water.

The action of caustic alkalies differs considerably accord-
ing to the quantity employed. Several times the amount of
alkali necessary for solution may be added without any very
appreciable change being produced, the solution merely
becoming somewhat thinner. On the other hand, if the

THE PREPARATION OF PLASTIC MASSES FROM CGASEIN. 139

addition of caustic lye be continued, the liquid commences to
thicken, and finally separation is effected into a perfectly
clear solution, containing the casein, whilst the opaque par-
ticles are deposited in the form of a sediment.

o o

a) a)
ao WS St
ants = ee
Sa a ; : B89 £3 : és
seu Behaviour of the Peds Behaviour of the Additional
Ay a x e Casein Solution. a B FS ne Casein Solution. Remarks.
ZO2s Boas
Ow 9 Fi, 2
— ° SG i= °o —

23°/, | Fairly thin, grey,}| 12°/, | Gelatinous, faintly

opaque, homo- greenish, perfectly
geneous solution. homogeneous,
34°/, | Somewhat thinner . translucent with
than the foregoing. the appearance of
boiled starch.

43 °/, Do. do. 13 °/, «| Thinner jelly. A sample,
eed fe Do. do. shaken up
ee LS Do. do. with cold
€ i: Do. do. water,
es Pe Do. do. separated
+ ae Do. do. into liquid

10 °/, | Whiter in colour, and sedi-

signs of thickening. ment.

11 °/, | Thick jelly. 14°/, | Perfectly water-

: white solution
11°/, | A sample turned separated from
green like whey on very voluminous,
boiling, and when muddy, whitish
left to stand, precipitate.

separated into an
imperfectly clear
liquid and a sedi-
ment.

Further experiments have shown that heat, concentrating
the solution, and prolonged standing, all favour the separa-.
tion, which, moreover, can be effected very quickly by a
single addition of alkali. Casein solutions prepared without
alkali, and even milk itself, can be converted in this manner
into a clear solution and a precipitate. The resulting clear
liquid is colourless, greenish-yellow, brownish, or red, accord-.
ing to the purity of the casein and to the temperature
employed.

140 CASEIN,

Since the various technical varieties of casein exhibit
different conditions in solution, in consequence of the
methods of preparation adopted, it is impossible to state a
minimum quantity of alkali that will cause separation in all
cases ; a preliminary test will, however, furnish the necessary
information.

The clear casein solutions prepared in the foregoing
manner can be treated—after removal of the sediment—in
the same way as the turbid solutions. For instance, the
casein may be precipitated by an acid, and used in place of
ordinary casein, or the precipitate may be dried—whereby it
becomes perfectly transparent—and worked up into artificial
amber, jet, etc.

The claim advanced for the method is for the preparation
of transparent masses by. treating casein, either dissolved or
suspended in water, with sufficient excess of caustic alkali to
precipitate the opaque particles, the casein being retained in
clear solution, from which, after removal of the sediment, the
casein can be precipitated and worked up in any suitable
way.

In a further patent (141,309, March 5, 1902) it is claimed
that the caustic alkali originally prescribed can be partly or
wholly replaced by alkali carbonates, further experiments
having shown that these carbonates have also a clarifying
effect when added in quantities larger than is needed to
dissolve free casein. The resulting clarification is not so
complete as when caustic alkali is used, the latter, however,
acting also on the sulphur compounds present in the casein
solution, causing a yellow discoloration of the clarified
solution or of the precipitated casein, unless the operation
be performed with extreme care. Hence when a colourless
product. is specially desired, ‘the caustic alkalies may be
advantageously replaced, wholly or in part, by the corre-
sponding carbonates.

THE PREPARATION OF PLASTIC MASSES FROM CASEIN. 141

For example, 55 gallons of milk, separated from impurities
as far as could be effected by repeated treatment in a centri-
fugal machine, were treated with 7? lb. of soda (equal to
about 40 per cent. of the weight of casein content). After a
short time the colour changed, and on passing the liquid
again through the separator, a greasy, muddy sediment was
eliminated. The casein, precipitated from the resulting
liquid by acids, was in thin sheets, colourless and transparent.

In German patent 147,994 (February 19, 1901) a pro-
cess was described for imparting to dried casein the necessary
plasticity to enable it to be moulded, this result being attained
by moistening the casein with a little acid, e.g., acetic acid,
instead of water, before pressing.

When freshly precipitated from milk, casein is plastic
and can be easily consolidated in moulds. On account of the
large percentage of water in this fresh casein, however, the
articles prepared from it are difficult to dry without warping
and cracking; the casein itself being also very liable to de-
compose during the long period required. On the other
hand, the use of the stable, dry casein is attended with the
disadvantage that it loses its original plasticity in course of
conversion into the commercial form, this plasticity not being
recoverable by simply moistening the dry product; conse-
quently, exceedingly high pressure and heat are required to
form the same into a compact mass. Asa result the colour
and hardness of the article may be seriously affected by the
heat.

The plasticity can, however, be restored by treating the
casein with a trace of acid, preferably at the stage of moisten-
ing the mass before pressing. The degree of acidity most
suitable varies, of course, with the different kinds of commer-
cial caseins, but may be easily determined by trial. The
acetic acid used for souring milk in dairies will do for the
purpose very well.

142 CASEIN.

To prepare a hard casein mass, casein, either in solution
or in the dry, soluble state, is converted into the insoluble
form by acids or salts, and treated with formaldehyde. It
is advisable to free the casein from excess of water, by
evaporation or pressure, before adding the formaldehyde.

The product obtained in this way, and known as galalith
(from the Greek, gala = milk, and lithos = stone)—a name
somewhat misleading since it cannot be regarded as petrified
-milk—has been adverted to by Dr. K. Hassack as follows:
The horny fundamental mass can be converted into pro-
ducts of manifold colours and uses by the incorporation of
pigments, earths, cellulose, ground cork, etc., with the casein
previous to hardening it with formaldehyde. Imitation jet
or ebony, for instance, can be prepared by adding 2 per cent.
of lampblack and precipitating with lead acetate, preferably
warm to secure a curd with less moisture. The precipitate
is triturated with water, drained and carefully dried on a
cloth strainer. Drying must proceed very slowly to prevent
cracking, and, therefore, takes several months. The resulting
dark grey cake is thoroughly soaked with formaldehyde, and
when dried and polished exhibits a glossy, deep black colour.
Other colours may be obtained by varying the pigment.
Thus, nickel sulphate, used for throwing down the casein,
gives a fine green mass, whilst copper sulphate yields a
peculiar bluish green, and so on. Very good imitation
marble is obtained by stirring mineral pigments with the
freshly precipitated casein, and particularly novel effects are
furnished by mixing bronze powders with the plain or
coloured casein, before hardening with formaldehyde. The
Gummiwaaren Fabriken (Rubber Works) of Harburg,
Vienna, produced at their various factories, by the aid of
pressure, sheets of galalith from ;4; inch thick upward. By
means of special tubular presses they make galalith tubes
and rods for turnery goods, knife handles, penholders, um-

THE PREPARATION OF PLASTIC MASSES FROM CASEIN. 143

brella and stick handles, chessmen, cigar-holders and mouth-
pieces for same, small boxes, buttons, dominoes, card
counters, inlays for cups, coloured furniture decorations to
replace coloured glass. These and many other articles are
now made of galalith in Vienna, Gablonz, and Nuremberg.

By pressing it in suitable moulds, galalith is also made up
into backs for brushes, hairpins, rings, and fancy articles, and
it is also made in sheets for cutting out combs of all kinds.
As a rule the mass is pressed before treating it with for-
maldehyde, but for thin articles this procedure may be re-
versed. :

Dr. Hassack and his assistant, Sudey, were engaged in
making comparative tests with galalith and celluloid; and
up to the present the following particulars are available.
The two substances agree closely in specific gravity, that of
galalith being 1°317 to 135, according to the admixtures
present, whilst celluloid is 1°34 to 1-4. In point of hardness
galalith is a little inferior to calc spar, namely, 2°5, whilst
that of celluloid is -below 2; and this substance can be
scratched by gypsum. One important difference in the
working qualities is that while celluloid can be easily cut
with a knife, galalith is difficult to cut, and chips a good
deal. With the saw or on the lathe they can both be
worked readily, but galalith the less easily on account of its
greater hardness. Both polish well, but galalith the better
of the two, giving a higher gloss. Celluloid is more elastic,
thin sheets and rods recovering their original shape at once
when bent or rolled, whereas galalith sheets or rods are
brittle when bent. Galalith also has the drawback that it
cannot at present be produced in sheets less than about
zz Inch thick; and unlike celluloid, which can be obtained
in transparent sheets as thin as paper, and in fine threads.
Neither can the sheets be obtained perfectly clear like glass;
nor is it so plastic as celluloid though it becomes soft, like

144 CASEIN.

horn, on prolonged soaking in boiling water. It gradually
absorbs a considerable amount of water when soaked, viz.,
according to experimental results, 30 per cent. in six days at
room temperature, and 33 per cent. in twelve days, swelling
and becoming like cheese, whereas celluloid absorbs barely
1 per cent. of moisture in the same time. Galalith is un-
acted on by fats, oils, benzol, ether, alcohol, or dilute acids,
but it swells considerably in alkaline liquids, which have no
action on celluloid.

Both materials are poor conductors of electricity. Thus
experiments made in the Vienna Technical High School
with plates of celluloid and of galalith ;; inch thick showed
both to be impervious to a current of 16,000 volts. The
points of superiority possessed by galalith over celluloid are
its freedom from smell and its uninflammable character. If
held in a flame it merely chars, swelling up and giving off
a disagreeable smell like burnt horn, whereas celluloid—a8 is
well known—ignites at once and continues to burn rapidly
with liberation of pungent vapours of camphor. The
non-inflammability and insulating power of galalith will
ensure its extended use in electrical work.

Galalith is made on a large scale at the Wimpassing and
Harburg works of the above-named company. ‘The casein
is obtained from dairies in Hungary, Bohemia, and Moravia,
where it is separated from sweet skim milk by rennet, the
whey being consumed for fodder. Galalith factories are
increasing in number in Europe. In 1910, at Lurgere
(France), 440,000 lb. of casein were converted into galalith—
the produce of thirty-five dairies which sent milk to the
factory. It requires 15°85 gallons of milk to produce 2°2 lb.
of galalith.' ,

A similar product to galalith is formed by heating casein

1 For the preparation and properties of galalith see G. Bonitt (“ Zeitschr.
angew. Chem.,’’ 1914, 27, 2).

THE PREPARATION OF PLASTIC MASSES FROM CASEIN. 145

with water under pressure and then hardening with for-
maldehyde (‘‘Soc. anon, franc. de Chim. Ind.,”, French
patent 425,204, 1910).

Insoluble Preparation of Casein.—Desgeorge and Lebriel,
in making a supple, insoluble preparation of casein and other
albuminoids, endeavour to overcome the defects of existing
methods, using metallic oxides, acids, etc., by utilising the
chemical activity of the electric current to increase the
_ absorption of these oxides or acids by the casein, and
consequently increase their effect. The casein is attached to
the positive electrode of an electrolytic cell, charged with a
bath consisting of water 1,000 parts, sulphuric acid 150
parts, and tannic acid 500 parts, the negative electrode
being formed of a plate insoluble in the bath. The sulphuric
acid supplies the casein with the sulphur, enabling it to absorb
the oxygen of the bath, whilst the tannic acid increases the
insolubility of the product and renders it supple and non-
putrefactive. The current decomposes the bath, liberating
hydrogen at the negative electrode, whilst the oxygen of the
acids present flows to the positive pole, where it is absorbed
by the casein. Harder products may be obtained by replacing
100 parts of the sulphuric acid in the bath by 50 parts of
phosphoric or other acid. ‘The tannic acid may be replaced
by other insolubilising agents according to the uses for which
the casein is intended. !

The Treatment of Casein and other Albuminous Sub-
stances.—R. Desgeorge, Lyons, and F. Lebriel, Villeurbanne,
claim: (1) A process for the treatment of albuminous
substances for obtaining non-inflammable products in imita-
tion of horn, shell, ivory, celluloid and the like, consisting in
adding to said substances a solution of chloride of sodium, and
submitting the product to an electrolytic treatment with
the use of metallic electrodes. (2) The process as in claim 1,

wherein electrodes of such nature are used as to impart colour
10

146 CASEIN.

to the finished product. (3) The process as in claim 1 or 2,
wherein the electrolytic treatment is continued until complete
insolubility of the product is produced.
The Condensation of Casein, Phenol, and Formalde-
hyde.—The condensation of phenol and formaldehyde in
presence of acids or alkalies to form a solid, inert substance
is the invention of Dr. Baekland; the product being well
known in America under the name of ‘‘ Baekelite”. K. Albert
and I. Berend (French patent 436,720, August 18, 1911).
have taken out a patent in which cordensation products of
casein, phenol, and formaldehyde are formed. This invention
consists im mixing together intimately 25 parts of casein, 25
parts of phenol and 2 parts of caustic soda. The mixture is
heated until it forms a viscous homogeneous liquid; 50 parts
more phenol and 10 parts of trioxymethylene are then added
and the heating discontinued when the temperature has risen
to 100° C. Further additions of 10 and 5 parts more of
trioxymethylene are made at intervals with further heating
until a sample removed solidifies on cooling. This product
can be readily moulded and can be hardened by heating at
100° to 110° C. or for longer periods at lower temperatures.
Other phenols may be used in place of ordinary phenol.

CHAPTER IX. -

USES OF CASEIN IN THE TEXTILE INDUSTRY FOR FINISHING
PURPOSES, COLOUR PRINTING, ETC.

CASEIN is used chiefly in calico printing, more rarely in the
finishing department. The gummy ammoniacal solution of
casein is employed as a medium for printing and fixing
powdered pigments that are unaffected by alkali. Fairly
well-fixed colours are obtained when the ammonia has been
driven off by vigorous drying or steaming. Solutions of
casein in lime-water can also be used in the same way; in
this case the colours are fixed by the action of the air, the
carbonic acid in which acts upon the compound of lime and
casein, forming calcium carbonate and insoluble casein.

Pure casein is almost entirely insoluble in water, but, as
already mentioned, it will dissolve in water containing car-
bonates, phosphates, alkalies or even alkali chlorides; weak
alkali being the most efficient solvent. These solutions, in
which the casein forms a weak compound with the alkali,
differ from solutions of albumen inasmuch as they neither
become turbid nor coagulate when heated. They, however,
acquire this property after the addition of magnesium sul-
phate, and turbidity also appears in solutions of casein in
lime-water, in which it is readily soluble. When casein
solutions are treated with mineral acids, a flocculent curd is
precipitated, which may consist of an adsorption compound
of the casein with the added acid. A similar precipitate is

produced by acetic acid, but is redissolved on adding an
(147)

148 CASEIN. |

excess of hydrochloric acid, though reprecipitated on the
amount of acid being still further increased.

Casein solutions are also precipitated by the action of the
mucous membrane of the stomach of the calf (rennet), and
also by the gastric juice of carnivorous animals. Precipita-
tion is also brought about by tannic acid and metallic salts,
indefinite compounds with which are formed, and parallel
to the behaviour of alkaline solutions of casein we find
natural solutions of the substance, such as milk, ROneTE in a
similar manner.

Caseogum, which is a solution of casein in lime-water,
is used as an adhesive, more particularly for impregnating
cotton and linen fabrics, and, on exposure to the air, absorbs
carbon dioxide. The casein, deposited on the fibre, imparts
to the latter greater affinity for dyestuffs.

Thirty-two parts of fresh curd are stirred with 48 parts
of water at 64° F. and rubbed through a metal sieve in order
to reduce it to a finer state of division. On the other hand,
? part of fresh, well-burned lime is slaked gradually with
warm water until it falls to powder, which is thereupon
mixed with 34 parts of warm water, triturated, filtered
through paper, and the solution added gradually to the curd
by stirring. The mixture at first thickens, and it is only
after prolonged stirring that it becomes thinner and attains
the desired consistency. Care must be taken to have fresh
lime of good quality, and to slake it with just the right
quantity of water; neither too much nor too little. The
curd must be rubbed down fine with the water so as to eradi-
cate all lumps, and the water must be at the pemiperatins
already specified.
| “Glutin.”’—*Glutin” is a glaze for dressing curtain

fabrics, also used as a medium for colours in dyeing and
calico printing. It is prepared as follows :—

Curd, freed from adherent moisture by pressure, is ground »

USES OF CASEIN IN THE TEXTILE INDUSTRY. 149

to a coarse, uniform powder, between rollers revolving in
opposite directions. This powder is mixed with a solution
of 1 part of sodium tungstate, and again put through the
rollers in order to crush the particles of curd as fine as pos-
sible. As soon as the solution is brought in contact with
the perfectly dry curd, the reaction commences at once and
the mass begins to grow tougher. Should the curd contain
much buttermilk, it is stirred up with a little hydrochloric
acid and water, and repeatedly washed with water until all
trace of acidity has disappeared. This done, the curd is
pressed again and used as above described.

The cold mixture containing the sodium tungstate is
placed in a water-jacketed pan, mixed with a little water if
too dry, and melted at a moderate temperature with con-
stant stirring, until a sample no longer shows any unaltered
curd. The mass may be preserved from putrefaction by
adding a little carbolic acid or oil of cloves. When the mass
is all melted, it may be poured out to cool, and then
furnishes a more or less solid mass, according to the amount
of water that has been added.

This material is soluble in water in all proportions, the
mass possessing highly adhesive properties, and it is particu-
larly useful for fastening paper labels on sheet metal. When
once dry, it is fairly waterproof. Curtains printed with
earthy or metallic colours and this preparation have a fine
gloss, and the coating 1s rendered more flexible by the addi-
tion of glycerine. “Glutin” is also soluble in glycerine,
forming therewith a fine, tough mass which, when applied to
paper, gives a flexible coating that can be made as hard as
leather by passing it through a solution of alum after drying.

Casein Dressing for Linen and Cotton Fabrics.—Four
parts of casein are stirred with 30 of water, followed by a
gradual addition of 1 part of lime that has been slaked to
powder. At the same time, 2 parts of neutral soap are

TOO =. 3 CASEIN.

dissolved in 24 parts of water, this solution being added to
the casein solution. The fabric is impregnated with this
preparation, and afterwards passed through a solution of
aluminium acetate, heated to 120° to 140° F., whereby the
casein is rendered insoluble and _ts precipitated on the fibre
along with the aluminium soap.

Argentine is the name applied by Heim to a special
powder prepared by the action of metallic zinc upon a solu-
tion of a tin salt, and the combination of this powder with
casein, as a dressing for yarns or fabrics, to impart to them
a metallic finish. |

The tin precipitate is obtained from a solution of “tin
salt’ (stannous chloride) by the aid of metallic zinc and the
electric current; the powder, after drying, being passed
through a gauze sieve, the coarse particles thus removed
being redissolved for use again, while the fine powder is used
in the preparation of the dressing.

The casein is prepared by moistening 1 part of casein
powder with water and allowing to stand for six to eight
hours, after which it is diluted with water containing strong
ammonia equal to one-quarter the weight of the casein in
which the latter swells to form a jelly which is diluted with
more water till a fluid is formed into which the argentine is
stirred. Should the material become thick on standing, the
vessel containing it may be placed in a pan of water, which
is heated, whereupon it becomes ready for use again immedi-
ately. To render the printing colour more workable it may
also be mixed with a strong gum-arabic solution, preferably
of a pale colour and well strained.

The casein solution may also be prepared in the following
manner, according to whether it is to be used as a dressing
for printing: 24 parts of casein are softened for ten to twelve
hours with 7 parts of lukewarm water containing ? part of
strong ammonia. During this time the casein will have

USES OF CASEIN IN THE TEXTILE INDUSTRY, 151

swollen up thoroughly, and can then be diluted with a further
7 parts of lukewarm water, after which acetic acid is added
until a precipitate is no longer visible.

The most important point in making this argentine
preparation is to have plenty of metal present, if the fabric is
to exhibit a silvery lustre when calendered, since it must be
remembered that the lustre is in nowise due to the medium,
but solely to the properly amalgamated finely divided metal,
under the influence of friction.

When printing colours or dressings become thick on
standing, they must not be diluted with any preparation,
but should be warmed in a pan of hot water or on a water
bath.

Printing Colour with Metallic Lustre.—According to
German patent 78,731, a preparation for producing on printed
curtains, and the like, the same effect as bronze powder, may
be obtained by treating powdered mica with an ammoniacal |
solution of casein and a dissolved metallic salt, and colouring
the whole with a vegetable or aniline dye.

Process for Softening, Sizing, and Loading Textile Fibres,
and for Treating Yarns and Fabrics.—In the process intro-
duced by 8. Carmichael, a bath is prepared by dissolving
casein in oil. If used for yarns and woven fabrics, the casein
may be dissolved in a solution of soap, and mixed with the
necessary loading ingredients. For example, the product
may consist of—

Casein . ‘ y f ‘ ‘ , : . 16 parts
Soap. : é r 4 ; p ‘ ; hace
Mineral or other oil ; Z ; > . as Sues 3 ‘ay
Water . : c ; , : ; j 68 ee ¥5
Loading ‘ ‘ ; , : : : get 3d ahah

The casein must be free from any acid impurities.
The materials to be treated are immersed in a bath prepared
by swelling casein in an aqueous solution of glycerine, lactic

152 CASEIN.

acid, dye, and the necessary loading ingredients. Ten parts
of powdered casein are mixed with 50 of water and a solution
of 2 parts of glycerine (30° B.) in 100 of water, the necessary
dye and loading ingredients being added when the casein is
thoroughly swollen. This casein bath may be acidified with
2 to 4 per cent. of lactic acid, without producing any precipi-
tation of the casein itself. By means of this bath it is possible
to finish and dye fabrics in an acid liquid, which was previously
impracticable with alkaline solutions of casein.

Fixing Casein and other Albuminoids on the Fibre, more
particularly in Dyeing.—Vegetable fibres, ¢.g., cotton, jute,
or flax, are steeped in a solution of casein in hydrochloric
acid, phosphoric acid, or lactic acid, and subsequently treated
with a saline solution such as sodium sulphate, ferric acetate,
sodium bichromate or sodium tungstate, capable of throwing
down from the casein solution a precipitate that is insoluble
in water. For instance, 10 parts of casein are dissolved in
200 of water and 1 part of 25 per cent. hydrochloric acid.
The cotton is steeped in this solution, and, after the excess
liquor has been removed by squeezing, it is passed through
a warm 10 per cent. solution of Glauber salt, and then washed.
The hydrochloric acid may be replaced by an equal amount
of 25 per cent. phosphoric acid, the material being afterwards
treated with ferric acetate and washed (German patent
139,565).

Fixing Insoluble Colouring Matters —The colours to be
fixed are printed with size or casein, the fabric being then
steamed or treated with a solution of formaldehyde. The
resulting insoluble compound of the latter substance with the
size or casein, envelops the colouring matter, thus fixing it
on the fibre, and rendering it waterproof. The printing
colour, prepared with dissolved size or casein, is treated with
the ammonia or bisulphite compound of formaldehyde and
printed on the fabric. This printing colour does not coagulate

USES OF CASEIN IN THE TEXTILE INDUSTRY. 153

at ordinary temperature ; it is only when the printed fabric
has been steamed or heated that the formaldehyde compound
is decomposed, the liberated formaldehyde combining with
the size or casein to form an insoluble compound. This
method has been patented and used in Great Britain. In
another system the printing colour is prepared with casein,
the printed and steamed fabric being exposed to the action of
formaldehyde.

Waterproofing and Softening Dressing.—The finishing
of textile fabrics has hitherto consisted in impregnating them
with a soluble dressing and then drying them, the dressing
thereupon solidifying on the fibre making the material more
or less stiff. This system, however, is attended with the
defect that when the fabrics are moistened the stiffness soon
disappears owing to the solubility of the dressing. The
defect in question can now be obviated by impregnating the
fabric with a soluble mass that is capable of conversion into
an insoluble form by means of chemical or physical agents.
According to a process patented in France, the fabric is
treated in the cold with a mixture of casein, albumen or
gelatine, and formaldehyde or hexamethylenamine, then
dried at 80° C., and finally steamed. The solution of the
colloidal substance may also be incorporated with pigments
or loading ingredients, such as barium sulphate, these being
fixed on the fibre when the albumen is hardened by the for-
maldehyde. Casein and gelatine are used in the form of 10
per cent. solutions, while the aqueous solution of formaldehyde
is of 1 to 2 per cent. strength. Formaldehyde bisulphite is
prepared by mixing 8 parts by weight of 40 per cent. for-
maldehyde with 10 of sodium bisulphite of 30° B. strength.
The hexamethylenamine is obtained from 8 parts of formalde-
hyde and 10 of concentrated ammonia.

Casein for Mercerised Crépe.—According to a German
patent process, the fabric is printed with casein or albumen,

154 | : CASEIN.

steamed to produce coagulation, passed through a concen-
trated solution of caustic soda (30° to 35° B.), squeezed
between rollers to express the superfluous lye, hung up for a
time to prevent an undue rise of temperature in consequence
of the mercerisation process, then acidified with dilute hydro-
chloric acid, washed and dried on a tentering frame.

Fixing Zine White on Cotton with Formaldehyde.—The
use of formaldehyde or formalin in cotton printing is based
on its property of coagulating casein, albuminoids, glue, etc.,
and rendering them insoluble. Thus, in printing metallic
powders and pigments on cotton fabrics, use can be made of
a compound, of casein or gelatine and formalin (Schering).
Moreover, formalin can be employed with advantage for
fixing zinc oxide, printed in a medium of casein and borax
on thin, transparent fabrics or on mercerised cotton goods.
The fabric remains soft, and the dull zinc white produces a
pleasing effect in contrast with the glossy ground; it can
also be toned to any desired shade by the addition of pig-
ments. At the same time it appears that the action of the
formaldehyde on the casein is more rapid and thorough in
an atmosphere of steam than in ordinary air. The fabric is
therefore put through a Mather and Platt machine, in which
the formaldehyde is vaporised and the zinc white is so firmly
fixed on the fibre that it will withstand boiling with soap for
a quarter of an hour. Finally, it should be noted that the
casein colours fixed with formaldehyde are as pure in tone as
those obtained with egg albumen, whilst considerably lower
in price.

W. Kay & Schoen print the cotton fabric with a colour
compounded of 34 parts of zinc white and 14 of casein-
borax medium; the goods being afterwards steamed for five
to ten minutes. In the bottom of the steamer is arranged a
perforated pipe, through which formaldehyde (40 per cent.)
is admitted in order that it may be vaporised in the steam

USES OF CASEIN IN THE TEXTILE INDUSTRY. 155

chamber and thus fix the casein and zinc white on the
fibre.

Casein is used for waterproofing fabrics and in calico
printing, being rendered insoluble by exposure to the vapours
of formaldehyde (J. E. Bousfield, F. Cantin, G. Miglioretti
and G. Maffei, English patent 1,160, 1901).

Casein-Magnesia.—Ten parts of powdered casein, 40 of
water and ? part of magnesia are stirred together for twenty-
four hours at the ordinary temperature, and afterwards added
to a solution of 0°3 part of barium hydroxide in 30 parts of
water, the whole being warmed to 95° F. forsome time. An
excess of barium hydroxide is injurious. This preparation
will fix mineral pigments sufficiently to be fast to washing.

Casein Medium for Calico Printing.—Six parts of casein
are well stirred up with 50 of water at 120° F., and left to
settle. The clear liquid is poured off and the residue is
mixed with 1 part of borax dissolved in 12 parts of water.

Chevalott’s Waterproofing Process.—The Chevalott pro-
cess is designed to deprive textile fibres of their capillarity,
and thus prevent them from absorbing water, without ob-
structing the interstitial spaces between the threads in the
fabric. The process is especially suitable for materials that
are to be worn next the skin, and have to be frequently
washed, ¢.g., underlinen, clothing, etc. At the same time the
fabric retains its softness and permeability to air, and can be
washed with soap, benzine, etc., without affecting its water-
proof properties. The preparation consists of a mixture of
about 40 parts of casein and 200 of water, stirred up until of
about the same consistency as cream. To this is gradually
added about 1 part of lime slaked to powder, which furnishes
a viscous fluid mass. At the same time 20 parts of neutral
soap are dissolved in about 240 of water and mixed with the
casein solution. The fabric is impregnated with this mix--
ture, so as to about double its original weight, and is then

156 . . CASHIN.

entered in a solution of aluminium acetate at about 120° to
140° F., which renders the casein insoluble and also reacts
with the alkaline soap to form an insoluble aluminium soap.
Finally, after having entered the fabric in pearly boiling
water, it is dried and ironed.

Loading Silk.—According to a patent granted to the
Chemische Fabrik auf Aktien in Berlin, the silk is repeatedly
soaked in a solution of casein or size, which may also contain
an addition of metallic salts. By afterwards exposing the
fabric to the action of formaldehyde, its weight may be in-
creased in this way by 30 to 50 per cent., without metallic
adjuncts. At the same time the gloss and scroop of the
silk are improved and the fibre is strengthened.

Threads, Blocks, Plates, etc., of Casein.—According to
H. Timpe (French patent 356,508, July 28, 1905), casein can
be converted into threads (like artificial silk), blocks, plates,
etc., by treatment in the following manner: When an
alkaline solution of casein or paracasein is treated with
acetone and boiled it separates into two portions: one soluble,
the other forming a flocculent white precipitate, which will
settle down by subsidence alone unless the solution is too
- viscous or too concentrated.’ It is, however, more rapidly
removed by means of a centrifugal separator. The liquid
portion is limpid and viscous, and when dried forms a clear
mass of considerable hardness which becomes plastic on
heating, and in this condition may be rolled out into thin
sheets or drawn into threads.

The casein may also be dissolved by solutions of alkali
sulphocarbonates, and coagulated by ammonium sulphate,
the product being drawn into threads, films, etc. {French
patent 395,402, 1907, and addition thereto, July 31, 1909).

Sizing Material.—H. V. Dunham, Bainbridge, New York,
assignor to the Casein Company of America (U.S. patent
897,885, September 8, 1908), claims the production of a

_ USES OF CASEIN IN THE TEXTILE INDUSTRY. 157

compound of hydrofluoric acid with casein—caseinate of
hydrofluoric acid—formed by the addition of commercial
hydrofluoric acid to heated milk, the proportions being 0°5
to 1 part of acid to 1,000 parts of milk. This product, mixed
in the proportion of 94 parts with 6 parts of borax and a
sufficiency of water, is recommended for sizing purposes.
For sizing purposes, T. J. Denne and A. Hentschel
~ dissolve the casein in ammonia (English patent 2,429, 1872).

CHAPTER X.

CASEIN FOODSTUFFS.

Ir is a well-known fact that animal albumen is a very
important ingredient in the food of man; and it may also be
accepted as proved that man should take one-third of his
requirements of albuminoids in the form of animal food. In
this connection, meat is the principal form of nourishment .
possible, since eggs, milk, and milk products have not the
same importance for dwellers in towns, soldiers and sailors,
and others similarly situated, as they have ‘for country
people. Besides, meat is the only form of animal food that
man can continue to take with pleasure in sufficient quantity
to satisfy the demands of the body for albumen ; in the case
of milk or vegetables, the consumption of the necessary
quantity sooner or later, with most people, causes a distaste
for the article. Now, in order to provide meat supplies at a
price which would enable the bulk of the populace to pur-
chase a sufficiency for the purposes aforesaid, it is not enough
to merely have recoyrse to cheap imported meat. On the
one hand, there is the difficulty of excluding disease, and, on
the other, the alterations to which the meat is exposed
(drying, pickling, smoking, etc.) in order to make it keep,
frequently affect its flavour and digestibility.

For this reason, said Dr. Adolf Jolles, in a paper read
before the Industrial Association of Lower Austria, it is easy —
to understand that the endeavours of modern chemistry
should have been directed to the discovery of some substitute

for the scarce commodity, animal albumen. The results of
(158) |

CASEIN FOODSTUFFS. 159

these endeavours have been utilised industrially, with the
result that there are now on the market a number of prepara-
tions complying more or less with the requirements of the
times. These requirements are as follows. In the first
place, the meat substitute must be relatively cheaper than
animal albumen. Secondly, it must be tasteless, inodorous,
of the character of flour, and not more than faintly tinged
with colour. Thirdly, it must be free from micro-organisms,
and be capable of keeping for any length of time without
undergoing alteration ; and, finally, it must be suitable to and
assimilable by the organism when taken in considerable
amount. :

The first substance coming under consideration as a raw
material for such preparations is milk, on account of it
containing casein. The cereals and leguminose are also
highly important, as cheap and readily available materials
rich in proteids. The number of such preparations is ex-
tremely large, but only the chief of those made from casein
will be dealt with here.

One of the cheapest preparations obtained from milk is
that known as Lactarine, which cost originally only about
43d. per lb. This preparation, which has been on the market
since the beginning of 1898, is an extremely fine white
powder, soluble in water, having the following composition :
water, 9°92 per cent.; fat, 0°'4 per cent.; casein, 78°16 per
cent.; non-nitrogenous (carbohydrates), 7°77 per cent.;
mineral matters, 3°75 per cent. With regard to the assimi-
lation of this preparation by the human organism, there is
no information at present available; nor, indeed, are there
any other particulars as the method of manufacture is kept
secret.

Galactogen costs about 1s. 10d. per lb. It is made from
skim milk by the addition of a patent preparation. The
albumen contained in the product is not coagulable by the

160 CASEIN.

heat of boiling water. The chief constituents are: fat, 3°5
to 4°5 per cent.; proteids, 70 per cent.; and phosphoric acid,
1°5 to 2°5 per cent. The flavour is agreeable, and the pre-
paration is said to be very palatable. As usual with milk
preparations, it is mixed with other foods.

Guttmann’s Nutrient Milk Flowr.—This milk food is a
mixture of several ingredients. Skim milk casein is mixed
with prepared carbohydrates, mainly gluten-free oatmeal and
a small quantity of aromatic substances. The preparation is
a fine white powder of agreeable flavour, and its proteid is
_ soluble in water. The composition is as follows: dry mat-
ter, 92°7 per cent., of which about 20 per cent. is albuminoids,
65 per cent. carbohydrates, and 4 per cent. fat. It is said
to be very digestible and liked by children and dyspeptics.
Its chief characteristic is the large proportion of readily di-
gestible carbohydrates; and for this reason its employment
might be indicated in suitable cases.

Sanatogen is another casein preparation. It is made by
a patented process, and consists of 95 per cent. of casein
and 5 per cent. of sodium glycerophosphate. It is a whitish
powder, inodorous, and nearly tasteless. Some people ex-
perience a disagreeable after-taste on first taking this prepara-.
tion and do not grow accustomed to it for some little time.
Sanatogen is assimilated in precisely the same way as meat
albumen; and, according to the results of experiment, the
assimilation is good.

Eulactol is also a mixed product. It is prepared by -
evaporating milk, according to a patented process, by exposure
to a temperature not exceeding 98° F’.., in vacuo, since other-
wise the fat would sustain alteration, leading to early
rancidity. The explanation of this appears to be that the
fat globules are surrounded by an albuminous envelope,
which is destroyed at higher temperatures, thus exposing the
contained fat to the air, whereas ordinarily it is protected

CASEIN FOODSTUFFS. 161

therefrom by the said envelope. Eulactol contains 33°25 per
cent. of proteids, 46°3 per cent. of fat, 14°3 per cent.. of
carbohydrates, and 4°3 per cent. of saline matter. It is a fine
white powder, in which both the albuminoid constituents
and the carbohydrates are mainly soluble. The preparation
is said to have been consumed by individuals for long periods
and in large doses and to have been well assimilated, though
no definite experiments have been reported. On account of
its low proportion of albuminoids the preparation cannot be
classed along with others of the same type.

The method of preparing Dr. Riegel’s Milk Albumen is
described in the patent specification as follows: The curd is
precipitated from milk by means of ethylsulphuric acid, in-
stead of the acids usually employed. This treatment leaves
the casein undecomposed, and throws it down in a compact,
non-mucilaginous condition. At the same time it is almost
entirely free frorn ash constituents at the first precipitation,
owing to the solubility of the lime salt of ethylsulphuric acid.
The content of free sulphuric acid is also very small.
The precipitation is effected with a dilute solution and at a
temperature of over 86° I’. It has been observed that the
casein contains a considerably smaller number of germs than
that obtained by acetic acid or lactic acid precipitation,
this being attributed to the germicide properties of ethylsul-
phuric acid. The preparation is free from pathogenic organ-
isms. Analysis reveals the following composition: casein,
86°18; water, 8°23; fat, 0°31; mineral matters, 5°27.. The
preparation is readily soluble in water, is devoid of any
specific odour, and has a by no means disagreeable flavour
when taken in small quantities. No experiments in natural
digestion have yet been made with the preparation.

Plasmon, formerly known as caseon, is an albuminoid pre-
paration obtained from milk. It is a yellowish-white powder,

of medium fineness, inodorous and with a faint flavour
+i

162 : CASEIN.

resembling sweet milk. It contains 75 to 80 per cent. of
casein, 5 to 7 per cent. of sodium carbonate, and 5 to 10 per
cent. of fat and milk sugar. There has been considerable
discussion respecting the probable presence of bacteria; but
at all events it appears to be free from tubercle bacilli. A
more important point, however, in connection with plasmon
is its assimilability; and on this point opinions are unani-
mous, all the experiments with it having given favourable
results. Moreover, it has been repeatedly determined that
casein is equal in nutrient value to lean meat, and is readily
absorbed in the intestinal canal. Plasmon can be used in a
variety of ways. For instance, it can be mixed with an
equal quantity of sugar, then boiled with water and eaten
in this form; and it can also be advantageously baked into
bread along with flour. Plasmon solutions may be incor-
porated with other foods without affecting their flavour in
the slightest degree; and, finally, plasmon biscuits, plasmon
cocoa, and plasmon chocolate are prepared and sold.

Dr. Schreiber says of fresh casein that it may be used as
a substitute for soup, and may be incorporated with flour in
bread-making without having any great influence on the
flavour, though greatly increasing the percentage ‘of proteids
at a very low cost. For this purpose the casein is preferably
prepared by acting on skim milk with commercial rennet,
the precipitate being drained from the whey and passed
through a sieve or mill, whieh delivers the product in the
form of fine flakes. These must be used while fresh, or they
harden. ;

Nutrium is a foodstuff prepared from casein, common salt,
and milk sugar. According to F. Bimbi, it forms a white -or
yellowish powder containing 29°1 per cent. of nitrogenous
substance. It dissolves in water, forming milky flakes and
giving an acid reaction. |

Casein Food.—A casein food, which dissolves without

/

CASEIN FOODSTUFFS. 163

any separation of gelatinous casein when boiled in water, is
obtained by mixing casein or its salts with substances con- —
taining albumose or peptone.

Casein as a Substitute for Egg Albumen.—According to
Pansiot, casein treated in the following manner is suitable
for replacing egg albumen for industrial purposes. ‘The
casein, mixed with water, is mixed with an excess of alkali,
preferably soda, and is then treated with 5 to 10 per cent.
of its own weight of sodium peroxide, added by degrees, with
vigorous stirring. The mixture is gradually heated to 65° to
70° C. without ceasing to stir the mass, and the oxidation of
the casein may be regarded as complete when the solution
becomes clear and all liberation of gas ceases. This clear
solution is cooled to 15° to 20° C., whereupon small quantities
of dilute hydrochloric acid (1:10) are stirred in till the mass
becomes milky. The precipitate is allowed to subside,
collected, and pressed to remove the water containing surplus
saline matters, after which it is washed by trituration with
water, care being taken not to prolong the operation which
would lead to solution of much of the product. Finally, the
precipitate is spread out on sheets of glass, and dried either
in the open air or bya current of air heated to not more than
35° to 40° C., or inany other convenientmanner. The product
is slightly yellow, translucent, and suitable for replacing egg
albumen, the properties of which substance. it possesses.

Synthetic Milk.—According to W. Hall’s patent (Dec-
ember 8, 1903) synthetic milk is prepared by stirring up an
aqueous solution of about 10 parts of sodium bicarbonate
with 85 parts of ordinary dry casein, the mixture being well
ground and treated with 2 parts of finely powdered calcium
chloride, following this treatment by incorporating with the
product about 5 parts of powdered milk sugar and 5 of butter
fat for each 44 parts of casein present.

Milk Food.—According to $8. Ramage (American patent

164 CASEIN.

730,702), milk is made slightly alkaline and heated, treated
with a coagulant, and the resulting casein exposed to a steam
pressure of 100 lb. per square inch until converted into
liquid amide caseose.

Emulsifiable Casein.—To obtain casein in a form which
emulsifies when boiled in water, it is mixed with a quantity
of an alkaline salt, insufficient to produce a soluble com-
pound; and this mixture, after being moistened with water,
is dried at a moderate temperature. The product on being
boiled with water gives a homogeneous emulsion closely
resembling milk. This preparation has been patented by the
Aktien-Gesellschaft fiir Anilin-Fabrikation, Berlin.

Casein Phosphate for Baking.—To prepare casein phos-
phate for bread-making, Hatmaker mixes a syrup of mono-
calcium phosphate, CaH,(PO,),—free from sulphuric acid—
and water with casein that has been precipitated from milk
by means of an acid and freed from milk sugar, salts, and
soluble impurities by washing with water. These ingredients
are intimately mixed by putting them through a mill, or in
any other suitable way, and the resulting thick, uniform mass
is finely dried at a low temperature in vacuo and reduced to
powder.

Another patent by the same inventor relates to the pre-
paration of a stable, non-hygroscopic compound of casein
with phosphoric acid, by concentrating an aqueous solution
of phosphoric acid to a syrupy consistency along with 1 part
of casein, and then intimately mixing this with the rest of
the casein, drying and grinding the product. This may be
mixed with an equal quantity of sodium bicarbonate and
used in bread-making. ye

Bernstein's Baking Preparation.—A baking preparation
consisting of casein and albumen is obtained by heating skim
milk, precipitating the casein, and converting the same into
a creamy condition by further mechanical treatment.

_~

CASEIN FOODSTUFFS. 165

Making Bread, Low in Carbohydrates, from Flour and
Curd.—Crude casein forms a useful adjunct in bread-making,
but in the ordinary method of baking its use is merely a re-
stricted one, since any excess over a very limited quantity
injuriously affects the dough, preventing it from rising pro-
perly. At the same time the milk sugar introduced in the
curd remains in the bread. These two drawbacks to the use
of the bread for invalids can be obviated by adding to the
dough and casein a proportion of peptone, albumose (or
substances containing the same), digestive extracts, albumin-
oids, or derivatives thereof.

Higgins’s Casein Food.—Casein is precipitated from skim
milk by hydrochloric acid, the product being dried, ground
to powder, and mixed with flour, rice, grits, tapioca, oatmeal,
arrowroot, bran, sugar, etc. ,

Preparing Soluble Casein Compounds with Citrates.—
Milk casein, in the moist state, is rubbed down with tri-
sodium citrate, with or without an addition of sodium bicar-
bonate or trisodium phosphate, and the product is dried.

Casein Food.—Milk casein or curd is dissolved and its
acidity, determined by testing, is partially neutralised, the
resulting mass being dried, sterilised and used as a food-
stuff.

Sell’s Curd “Zwieback”’ Rolls.—Precipitated casein is
mixed with milk sugar, exposed to the action of kephir
ferments and neutralised, the product being absorbed by
Zwieback powder (Zwieback is a kind of roll made in
Germany) and dried.

Food Powder.—Casein is treated with a suitable digestive
agent or enzyme which renders it soluble and at the same
time partly peptonises it. The process is arrested by drying
the product in thin films on cylinders heated to a temperature
of about 212° F., whereby it forms a product which is easily
pulverised, forming a very nutritious food (A. A. Dunham,

166 CASHIN,

New York, assignor to the Casein Company of America,
U.S. patent 750,832, February 2, 1904).

Substitute for Egg Albumen.—A rather remarkable pro-
duct is the subject of a patent granted to A. Berstein (French
patent 347,135, October 15, 1904). This material is formed
by dissolving 100 parts of casein with 650 parts of water, and
35 parts of ammonia solution (sp. gr. 0°98). To this is added
35 to 45 parts of sodium silicate and sufficient acetic or
hydrochloric acid to render it nearly neutral. The result is
a thin fluid, but on heating it becomes much thicker and is
then suitable to be used for cementing purposes. On evapora-
tion at a low temperature it yields a dry product which it is
stated can be used in place of egg albumen.

CHAPTER XI.

SUNDRY APPLICATIONS OF CASEIN.

Uses of Casein in the Paper Industry.—An important
part is played by adhesives in the industries wherein paper
is employed, both in order to inseparably fasten together
individual sheets of paper, convert paper pulp into a mould-
able condition, and also for the application of thin layers of
colouring matter or other coatings on paper or millboard
articles. Such coatings may be either matt or more or less
glossy, but in any event must be able to withstand to a
certain extent the influence of moisture. For all these pur-
poses casein is, per se, admirably adapted, since it will cement
sheets or bands of paper together and forms thin coatings of
considerable elasticity either alone or in association with other
substances, colouring matters in particular. When a solu-
tion of casein is treated with small quantities of formalde-
hyde, and the article coated with the preparation is exposed
to the air, a number of new products can be obtained. Thus,
for instance (by patented processes) we obtain waterproof
paper that can be used instead of guttapercha paper,
waterproof cardboard boxes and cartridge cases, washable
wall papers, washable paper garments, coloured papers, art
papers, transfer papers, and so on. Utensils, more particu-
larly basins, dishes, and the like, made of paper pulp or
millboard, can be rendered waterproof by treatment with
formaldehyde, and used for a variety of purposes, ¢é.g., as
developing dishes in photography. Similarly, cardboard

treated in the same way can be used for stereotype matrices,
(167) :

168 | CASEIN,

which will keep for any length of time, by reason of its light-
ness and durability. It is thus evident that the field of
application open to casein is practically illimitable.

Metachromotype Paper.—This paper, which is used for
transfer pictures, is preferably made of a fairly good, unsized
or lightly sized but smooth paper, capable of readily absorb- -
ing the thin solution of casein (preferably prepared with
sodium bicarbonate) and of softening with similar ease when
it has to be released. Since imperfectly coating the paper
with the adhesive will result in a defective impression, it is
evident that the coating must be perfectly uniform. The
operation is best performed with a flat brush, the paper being
spread on a table and the casein solution applied smoothly
by working the brush in one direction. If necessary the
coating is repeated, the brush being then worked at right
angles to the previous direction.

The prepared paper is next hung up to dry on lines in a
gently warmed room, preferably in a stretched condition to
prevent it curling. It is afterwards cut into sheets and
packed, either with or without calendering to smooth the
surface. |

Sizing Paper with Casein.—Notwithstanding the most
scrupulous care bestowed on the preparation of the resin
soap used in sizing paper, it has been found impossible to
impart the desired firmness and impermeability to the paper
by the use of vegetable size. In view of the large quantities
of casein now obtainable as a result of butter-making on the
large scale, in which casein has had only a very limited appli-
cation, it seemed advisable to test its suitability for sizing
paper; and with this object comparative experiments were
carried out by Dr. Zanardi with resin soap and casein
solution. :

Paper pulp was mixed with dissolved casein for twenty
minutes, and to the mixture was added a solution of alum

SUNDRY APPLICATIONS OF CASEIN, 169

—as in resin sizing—followed by diluted sulphuric acid until
a faintly acid reaction was produced. In the trials the casein
was poured on at the same time as the resin soap, or else
after the latter had been precipitated by aluminium sulphate.
In general the addition of casein was found to have a favour-
able influence on the firmness of the paper and on the amount
of size consumed. Casein can also be used for this purpose
by itself, furnishing a coating that will make the paper easier
to roll up.

Waterproofing Paper—This process is devised for making
paper and fabrics waterproof to such an extent that they
will stand protracted exposure to the influence of moisture
without losing their softness and elasticity. At the same
time they are made superior to paper or fabric coated with
caoutchouc, both from the point of durability and freedom
from smell. )

The principal features of the process are that the paper or
other material to be waterproofed receives two waterproof
coatings in succession, the first consisting of a specially pre-
pared solution of glue or casein (or mixture of both), which,
when warmed and treated with certain additions, remains
permanently supple and elastic.

In carrying out the process, glue or casein is dissolved in
water or other suitable solvent and treated with an addition
of sodium tungstate to improve the tenacity (if desired), the
albuminous substances being then precipitated by tannin or
other suitable precipitant as a viscid insoluble mass.

This mass, which is elastic and plastic while moist, be-
comes very hard and brittle on drying, so that it would be
entirely unsuitable for the purpose in view were it not cor-
rected by melting it in a pan (preferably before it has set)
and adding glycerine, syrup, molasses, fats or oils, alone or in
conjunction, the whole being well mixed. The quantity of
materials so added depends on the degree of suppleness

170 SE Raa
desired, and_is preferably about one-half of the mass obtained
by the aforesaid precipitation.

The resulting mass for the first coating can be applied
to paper or fabric before it has set, forming a very flexible,
insoluble coating resembling caoutchouc. ‘To make the
paper keep better it may be at once mounted on fabric by
pressure, or pressed between two similarly treated sheets or
roll lengths of paper. Of course the fabric may have been
_impregnated beforehand, or else the joined paper and fabric
may be treated afterwards.

To improve the waterproofing qualities and impart a fine
gloss, a second coating is applied consisting of any convenient
waterproof varnish or lacquer. Colouring matters can be
incorporated with the first or second coating, according to
choice.

Casein Solution for Coating Paper.—A casein solution,
suitable for coating paper and for other purposes, can be
prepared, according to W. A. Hall’s English patent, by
- mixing casein (precipitated with hydrochloric acid) with 10
to 15 per cent. of its weight of sodium phosphate, preferably
trisodium phosphate, and 1 to 3 parts of water to each 1 part
of casein. :

Horn’s Clear Solution of Casein.—A clear solution of
casein, free from fatty substances, is obtained by treating a
10 to 20 per cent. solution of casein with 7 to 8 per cent. of
caustic potash (according to the amount of dry matter), the
‘whole being shaken up with ether for a short time and run
into a settling vat. The clear solution of casein subsides and
can be drawn off.

Facing for Paper.'—Casein 1 lb., water 34 lb., borax 3
oz., these are heated together until dissolved. Ammonia may

10On the testing of casein for paper facing, see E. Sutermeister, ‘‘ Paper
Making,’ 1914, 33, 140-143, 187-190. ‘This author states that casein precipitated
by rennet is not suitable for use in paper-making.

SUNDRY APPLICATIONS OF CASEIN. 171

wy

be used in place of borax in the proportion of about 1 part of
strong ammonia to 5 parts of casein, with water sufficient to
form a workable fluid? The white materials used for facing
consist of China clay and satin white in the proportion of 75
parts of clay to 25 parts of satin white.

For glazed or faced waterproof papers, of good quality
and in any colour, 100 parts of pure casein are mixed with
1,150 parts of cold water, 15 parts of borax being then added,
and the mixture thoroughly stirred. Heat is applied by
means of steam until a temperature of 70° C. is reached ”
which must not be exceeded. When the solution has become
perfectly homogeneous it is strained through a sieve, and
there is added thereto 750 parts of kaolin, satin white, or
other white material, followed by 10 parts of 40 per cent.
formaldehyde, and, when specially pure whites are desired, a
little ultramarine also. A cheaper formula for low grade
papers consists of: 100 parts of casein mixed with 1,150 parts
of water and dissolved in 30 parts of ammonia 26° Bé. (or 50
parts of soda solution 6° Bé.).

For a sizing material for paper 100 parts of casein are
mixed with 450 parts of water and 15 parts of sodium car-
bonate, the whole being stirred till thoroughly mixed and
heated at a temperature below the boiling-point until com-
pletely dissolved. The size may be obtained in a thicker
condition by reducing the quantity of water. This solution
increases the beauty of colours, facilitates the finishing
operations, and imparts properties which are useful in the
printing and folding, besides imparting a silky feel. Paper
sized in casein solution can be damped by immersion in hot
or cold water, and will receive and retain the ink after drying,
just as though it had not been damped. This property is
especially valuable in connection with State papers, and other
important documents which it is desirable should be protected
from damp.

Bs
-

172 CASHIN,

Water- and Fireproof Asbestos Paper and Board.—
An essential preliminary to the manufacture of asbestos
board is to isolate the asbestos by chemical means, in order
that it may retain its flexibility in presence of the subse-
quently added ingredients, and not become brittle. This
treatment is preferably effected by means of an acid, a saline
solution, or dilute glycerine, the latter being more convenient
in practice. The asbestos is first mixed with 4 to 6 per cent.
by weight of glycerine, followed by 5 to 10 per cent. of water.»
The medium formerly used for binding together the fibres of
asbestos was fish glue (especially in the Ladewig process) ;
but casein will accomplish the same purpose more effectually
and at far less cost.

The mixed asbestos and casein (¢.g., casein and borax
solution) is next reduced to a fine pulp in a mill. This
impregnation isolates the asbestos fibres and prepares them
chemically in such a manner that they are no longer exposed
to any injurious action on the part of subsequent adjuncts, as
was formerly the case.

~The well-ground mass is treated with 2 to 3 parts of
rosin soap (previously dissolved in hot water), the whole
being well mixed and afterwards treated with about 6 parts
of zinc chloride dissolved in 15 to 25 parts of water, and
finally 20 parts of graphite in suspension in about 50 parts of
water is added. The graphite makes the mass fireproof and
imparts to it the appearance of vulcanite.

For use as a packing material in pipe joints that have to
be frequently opened, this material may be covered with wire
gauze on one or both sides.

The finished, intimately mixed mass is worked up into
paper or millboard of any desired thickness, in the machines
usually employed for these purposes. 'The product ‘is after-
wards pressed, dried in the air, and impregnated with a 1 per
cent. solution of zinc chloride. It is then redried, passed

SUNDRY APPLICATIONS OF CASEIN. 173

through a $ to 1 per cent. aqueous solution of rosin soap
(prepared by dissolving the rosin soap in spirit and diluting
with water), and finally dried again in the air. The appear-
ance is improved by calendering. The finished article is
elastic and completely fire- and waterproof.

Asbestos millboard is prepared as follows :—

Whereas long staple asbestos is required for spinning
purposes, the short fibres of ordinary quality are more suit-
able for the purpose now in view. ‘The short fibres separated
from those of longer staple by screening, prior to the spinning
process, are ‘also used. The crude asbestos is put through
an opener to break up the fibres, and the material is then
softened with boiling water, after which it is ground in a
mill of exactly similar type to those employed in paper-
making. This consists of a long, rectangular, wooden, stone
or iron trough, filled with water and containing a revolving
roller provided with steel rails, underneath which is arranged
a massive oaken block inlaid with a row of knives. The
trough is divided into two parts by a central partition, over
which the asbestos fibres are flushed by the water into the
working compartment, where they are acted on by the roller
and knives. A hood placed above the roller prevents any of
the fibres being thrown out of the trough by centrifugal
force. Means are provided for setting the roller progressively
closer to the knives, so as to reduce the fibres more and
more. At the same time the medium—casein, starch, gum,
etc.—employed to bind the asbestos together, is usually added
in the mill.

The further treatment of the asbestos pulp is on precisely
the same lines as in dealing with paper pulp for the manu-
facture of machine-made paper. The pulp is delivered on to
an endless seive of metallic gauze, to which is imparted a
vibratory motion to facilitate the draining away of the water ;
after which it is passed between rollers to squeeze out more

174 CASEIN.

of the water. By means of an endless belt the pulp is next
fed to a second pair of rollers, after leaving which it still
contains a considerable amount of water. It is cut up into
squares, which are placed between zinc plates ; a number of
these alternating layers being put into a powerful hydraulic
press, after leaving which the pulp boards are hung up in
a steam-heated chamber, to get rid of the last traces of
moisture. ?

Asbestos boards can, of course, be made in varying thick-
nesses. The ordinary makes are composed of 6 to 12 and
even more layers, placed one above another and united by
passing them between rollers and in the hydraulic press.
The usual thicknesses are 4, ?, 1, 14, 2, 24, 3, 4, 5 to 10 and
15 millimetres, the sheets being generally 40 inches in length
and breadth.

The chemical composition of the mass varies to an extra-
ordinary degree. Most kinds are greatly adulterated, con-
taining not more than 50 per cent. of asbestos, and that, too,
of inferior quality. It cannot be too strongly emphasised
that the valuable properties of the asbestos are the more
apparent in proportion to the quality of material used and
adjuncts are shunned.

Paper Flasks, etc., for Oilsand Fats.—Vessels of different
shapes can be manufactured from paper by reducing well-
sized paper to pulp. A useful paper for this purpose consists
of about the following proportions :—

Rag. ; , ‘ ; ; , ‘ ; 10 parts.
Straw . ; ; SS see ; , : nas. |, seen
Brown cellulose . ‘ . ‘ ; : : a

The paper is impregnated with a solution of casein, in
order to render it impermeable and at the same time to
make the individual sheets of paper adhere together. With
this object in view the sheets of paper are coated on both

SUNDRY APPLICATIONS OF CASEIN. 175

sides with an ammoniacal solution of casein, laid one on top
of the other, and at once placed in heated moulds, the pulp .
being forced, by means of a press, into a tray or basin of the
form most suitable for the purpose in view.

The moulds are made in two halves, one hollowed, the
other raised, and fitting into it, leaving sufficient space for
the pulp. In the case of a flask or bottle, for instance, the
hollowed portion is fitted at the top with a lug for receiving
the stopper, with the neck, and, underneath, the part on
which the bottle is to stand. The stamping mould is gently
warmed before the paper is inserted, so that the casein solu-
tion sinks more deeply into the fibres of the latter, and at the
same time the ammonia has a better chance of evaporating.
After a short time the paper mass will have set hard, when
the finished half bottle can be taken out, and left in the air
to dry completely. These halves are afterwards thinned
down at the edges where they are to be joined, pressed
together, cemented with casein glue, and coated with a thin
layer of casein solution both on the interior and exterior.

Washable Drawing and Writing Paper.—Any conven-
ient kind of paper is treated with a first coating of casein,
size, or other suitable medium containing an admixture of
some finely pulverised mineral substance, such as zinc white,
chalk, lime, heavy spar, etc., and the requisite colouring
matter. It is then brushed over with, or dipped in, water-
glass containing a small quantity of magnesia, and left in the
air for a short time to dry, at a temperature of about 77° F.
This second coating may be replaced by one of dilute formal-
dehyde. 7
Paper treated in this way may be written or sketched
‘upon with pencil, chalk, coloured crayon, charcoal, transfer.
ink, or lithographic ink; and the marks thus produced may
be washed off again wishious any appreciable alteration of
the paper,

176 CASEIN.

Paper of this kind possesses the advantage of economy
_ when used in schools or by designers. In drawing plans,
for instance, the design can be easily and rapidly removed
with a damp sponge, and a fresh drawing made at once on
the same sheet. Such paper forms an excellent substitute
for the heavy slates used in schools for writing and drawing
lessons ; and is advantageous for this purpose, inasmuch as
it can be made in colours that will not fatigue the eye.

Nevertheless, it cannot be denied that repeated writing
and washing soon wears out the protective coating, so that
the sheets do not last very long, especially under the heavy
wear to which they are subjected in school work. ;

Paper Wrappering for Food, Clothing, etc—The custom-
ary practice of protecting clothes from the ravages of moths
and other insects by bestrewing the articles with naphtha-
lene, camphor, pepper, and so forth when they are laid away
for some time, is attended with numerous inconveniences,
not least of which is the unpleasant smell of the substances
in question. These can be avoided by the use of paper or
linen prepared by a simple process in such a manner as to
permanently resist insect attacks, and also atmospheric in-
fluences, so that they may be used in packing goods destined
for consignment to a distance.

The process itself is based primarily on the well-known
disinfectant properties of formaldehyde, and on its capacity
for forming a waterproof coating with the aid of casein.

Hence, if paper and similar materials or finished articles
made from the same, such as bags, wrappering, and the like,
be soaked in a warmed solution of casein, containing an ad-
mixture of wax, soap, caoutchouc solution, etc., for mparting
increased flexibility, and these impregnated articles be then
dipped in a solution of formaldehyde, they will become
covered with a thin insoluble film. While this is still moist,
several sheets of the prepared paper, or of such paper and

SUNDRY APPLICATIONS OF CASEIN. 177

linen, can be united together to form a more or less thick
and compact material. Finished cardboard goods, boxes, etc.,
can also be covered by the same means with such moth-resist-
ing paper. Itis also advantageous to fasten cotton wool on to
paper or linen by means of the formalin-casein adhesive or by
sewing, and then impregnate the wadding with formaldehyde.

If, on the other hand, greater importance is attached to
the waterproof character of the preparation, this result may
be attained in various ways, for instance, by steeping the
paper in a solution of paraffin in benzol, a solution of shellac
and borax, alcoholic solutions of rosin, or by coating with
viscose (cellulose thiocarbonate), either in conjunction with
dissolved casein or following the treatment with the latter.
Fine fabrics may be waterproofed by the same means or in
conjunction with alumina, aluminium mordants, ammoniacal -
copper oxide, oil, etc.; in any case, however, a liberal amount
of formaldehyde must be used. If the effect is found to have
weakened by lapse of time, it can be renewed by the applica-
tion of formalin (40 per cent. formaldehyde).

Materials rendered in this manner proof against germs,
water and insects, are manifestly applicable to a large num-
ber of purposes. Among these may be mentioned the storing
and conveyance of foodstuffs, especially in humid climates;
also as wrappers for anatomical and zoological preparations,
and other objects liable to decomposition. Furthermore, they
may replace the more expensive oiled linen wherever a light,
but resistant, waterproof and cheap wrappering is needed.
Special attention is called to the manufacture of impregnated
paper bags, which would meet with a ready sale for storing
clothes ; also portfolios for storing documents and antiquities,
such as lace, water-colours, etc., in museums and collections.

Paint Remover——During recent years the practice of
removing paint by burning has fallen into desuetude. The

caustic alkali preparations, however, now sold for this
| 12

178 | CASEIN.

purpose are attended with numerous drawbacks, the ordinary
substances of this class in order to be effective having to be
applied several times, owing to their tendency to run down
from the smooth surface of the paint, so that their action is
minimised. This tendency, however, may be prevented by
mixing the alkali with a very thin solution of casein, in the
proportion, say, of 5 parts of caustic soda, 10 of water,
and 1 of casein solution. The caustic soda is first dissolved
in the water, and the casein solution is added until the
preparation is of workable consistency. For use, the mass is
stirred up well, laid on with a brush, and washed off, along
with the remains of the paint, in about one to two hours’
time. ‘To enable this preparation to keep for some consider-
able time, the addition may be made of 4 per cent. of carbolic
acid and a few drops of some ethereal oil, such as oil of
cloves, rosemary, etc.

Beuse’s Shoe Polish.—Shoe polish may be made to give a
greatly improved gloss by the addition of a solution of casein, —
prepared by boiling in water with borax or soda. At the
same time the addition of iron rosinate imparts the property
of staining the leather a deep black, instead of merely
forming a black coating.

The iron rosinate is prepared by adding an aqueous solu-
tion of green vitriol (ferrous sulphate) to a rosin soap obtained
by boiling rosin with soda. The other ingredients of the
polish are as usual: ivory black, syrup or dextrose, fat or oil.
A blue-black sheen may be imparted to fine polish by the
addition of a little Paris blue dissolved in water.

The following is a typical recipe for such a polish :—

Casein , > : ; é 16 parts by weight.

Soda crystals . ‘ ; ; 6 parts dissolved in
Water . ‘ i ; ; 48 parts, and mixed with
Ivory Black . ‘ ‘ ‘ 145°. 5; :
Dextrose . i P " ‘ TP oa;

Olive Oil . ; ; 5 ; 124 ,,

Iron rosinate . , : ‘ Ds

SUNDRY APPLICATIONS OF CASEIN. 179

This should be further mixed with 5 parts of ferric
ferrocyanide, dissolved in 1 to 2 parts of oxalic acid and 5 of
water, the whole being stirred in a suitable stirrer. For
solid polishes, the proportion of solid ingredients is increased.

Casein Shoe Cream.—Casein exhibits the property of
furnishing with thick turpentine a handsome, shining com-
pound, suitable for various purposes, especially shoe polish.
For this purpose 4 parts of galipot are melted, strained
through a sieve, and boiled with 3 parts of water and 2 of
caustic soda lye (density, 37° B.) until a film has formed on
the surface, whereupon another 1 part of the soda lye and
50 to 60 parts of warm water are added; 15 parts of soda
crystals are dissolved in the liquid, and 10 parts of powdered
casein are stirred in until dissolved. This is followed by 10
parts of grey carnauba wax, following which the whole is
boiled until homogeneous. If a cooled sample be found too
stiff, a little water is added. An aniline dye that is fast to
alkali may be used for colouring. :

Casein Photographic Plates.—With the invention of the
_ silver bromide dry plate, which rendered outdoor photography
possible, arose the necessity for replacing the support (the
glass plate) by some material which, whilst possessing the
transparency of glass, is free from the objectionable properties
of fragility, weight and bulk.

Endeavours have been made to overcome this difficulty in
‘various ways, but though films of celluloid, paper, mica, and
gelatine have been proposed in place of glass, celluloid alone
has been able to hold its own for this purpose. Neverthe-
less, this substance also has its defects, being in the first
place highly inflammable, subject to electrical discharges
which spoil the photographic image, liable to curl in the
various baths, and, finally, very expensive in comparison with
glass plates.

The use of casein for the purpose in question appears to

180 a CASEIN.

have solved the difficulty of finding a material that is free
from the above-mentioned inconveniences.

Wood-Cement Roofing Pulp.—This new roofing pulp has
the advantage over tarred pulp in being fireproof as well as
waterproof, and of' not softening with heat. It is made of
cellulose pulp board, painted over with the following
composition :—

Slaked hme ; ‘ : : ; ‘ - 100 parts
Casein . : " : : ‘ : : 10

9

the latter being dissolved in water, stirred up to a pulp with
the lime, and gradually thinned to the consistency of syrup.
Four applications are generally sufficient to produce a coating
of the requisite thickness.

The sheets may alternatively be dipped in the composition,
the latter being in that case made correspondingly more fluid.
The waterproof character is increased, and a fine gloss im-
parted, by applying to the finished article a coating of shellac
and borax solution.

Cask Glaze of Casein and Formaldehyde.—The wooden ©
casks used for the transport and storage of wine, beer, etc.,
are liable to become infested with mould fungi and bacteria
when lying empty, and must therefore be carefully cleansed,
before being again used, with boiling water and some dis-
infectant, such as lime, etc., and then dried. Even after this
treatment, no security exists against the contamination of
the liquid contents, or at least against their acquiring a
flavour from the cask. In the case of beer barrels, it has
long been the practice (in some parts of the Continent) to
line them with pitch, which, however, is liable to crack and
peel off, so that not only is the beer contaminated with
fragments of pitch, but the cracks in the coating afford an
excellent harbouring place for the development of bacteria.
It is true that shellac dissolved in spirit has also been used

SUNDRY APPLICATIONS OF CASEIN. 181

for varnishing the interior of these casks; but that process in
turn has drawbacks which preclude its employment in many
cases. }

It is an essential condition of a good cask lining that the
coating shall adhere strongly to the wood, and that it should
be insoluble in any of the liquids which may be stored in it.
It must not impart to them any taste or smell, and, finally,
must form a smooth coating resembling glaze, without any
tendency to crack or peel off.

Such a preparation has been made by the Union Aktien;
gesellschaft fiir Chemische Industrie, of Vienna, in the form
of a solution of casein and formaldehyde, which is claimed to
be an efficient substitute for pitching, paraffining or varnish-
ing beer and wine casks.

According to this patented process, the casks are lined
with a small quantity of an ammoniacal solution of casein,
glue, or gelatine, containing a little formaldehyde, this mix-
ture being shaken up in the cask for a short time and the
excess then allowed to drain away. ‘The casks are next
dried by the admission of heated air, and are finally rinsed
out with formaldehyde soijution, in order to render the film of
casein perfectly insoluble.

Exhaustive experiments have dermseatvatol that the beer
will keep in as sound a condition in the casks so treated as
in those lined with pitch.

The absolutely permanent casein coating prevents any
loss of carbonic acid; the coating will not peel off from the
cask staves; and when it has suffered any injury from
mechanical abrasion, it may be easily repaired by further
treatment with casein solution. Being completely insoluble,
there is no risk of the beer acquiring any flavour due to the
absorption of casein. :

The solution of! casein and formaldehyde acts as an
antiseptic ; and the same property being possessed by the

182 CASHIN.

resulting coating, helps to preserve both the contents and
the material of the cask. | |

The casein coating is insoluble, not only in alcoholic liquids,
such as wine, beer, etc., but also in acids and weak alkalies.
Hence it can also be used for casks destined for the transport
‘or storage of liquids belonging to these last-named classes.

The Preparation of Artists’ Canvas.—Large quantities
of canvas are used by artists and scene painters. The
material is mostly rough linen, more rarely jute, which re-
quires—before being used for painting—to be coated with
some composition that will convert the rough surface into a
smooth and continuous one that is adapted to receive the
paint. This operation is termed “priming,” the material
thus treated being known as primed canvas.

The canvas is required to be perfectly smooth and to
remain so without alteration. Canvas that would warp
and get out of line would distort the painting, thus causing
the latter to lose entirely its artistic value. Since artists’
canvas is almost invariably sold in condition ready for being
stretched on a frame and painted upon, it is advisable for the
maker of this prepared canvas to commence operations by
stretching in such a manner that the tension will be the
same in all directions. The priming composition is then
applied to the surface by simply painting it on with a wide
brush.

Some makers use for this purpose a composition consist-
ing of chalk and driers, coloured grey by the addition of a
dark pigment. The use of driers, however, cannot be recom-
mended; indeed, it is probably owing to their employment
that so many paintings are found to crack within a few
years’ time.

When the canvas is primed with a quick-drying varnish
the prepared surface appears to be perfectly dry and suitable
for painting on at the end of a few days, since good driers

SUNDRY APPLICATIONS OF CASEIN. 183

cause the material to set hard very quickly on exposure to the
air. This hardness, however, is merely superficial, the under
layers of the composition remaining soft for a very long time,
becoming resinified only very slowly. When this resinifica-
tion has reached a certain stage the stratum of varnish con-
tracts strongly and invariably cracks.

The pigments of the painting, which are firmly attached
to the priming, are constrained to follow this contraction ;
and this phenomenon is first manifested by the disappear-
ance of the gloss on the surface. Examination of such a
picture with a strong magnifying-glass reveals the presence
of innumerable fine cracks over the whole surface; the end
of the picture can then be predicted with certainty, namely,
that it will eventually crack to such an extent as to become
quite indistinct and worthless as a work of art.

There is, moreover, another very potent reason against
the use of varnishes in preparing artists’ canvas, namely,
that many varnishes are made by the aid of lead prepara-
tions. It has already been remarked on several occasions
that lead preparations are particularly susceptible to the»
action of sulphuretted hydrogen, which turns them black;
and consequently paintings on such canvases will become
darker coloured in course of time.

Many artists’ colours in general use, such as cadmium
yellow (Jaune brilliant) and vermilion, are, moreover, com-
pounds containing sulphur. When such sulphur compounds
come into contact with a priming containing lead, it follows
that they will undergo an entire change, often in a few
years turning brown and even quite black. Hence, even
when an artist carefully avoids the use of lead pigments, in
order to increase the life of his work, his precautions are
rendered nugatory should he unhappily use canvas that has
been primed with a composition or varnish containing lead.

For this reason the use of casein for priming offers a

184 CASEIN.

series of noteworthy advantages ; and it is especially indicated
where the risk of cracking comes into consideration. A can-
vas prepared with casein is more durable and comparatively
cheaper than one primed with linseed oil varnish, and very
little dearer than when distemper is used in priming. .

Casein soluble in alkali or in water may be used, the
latter being preferable since it is prepared on a manufactur-
ing scale. The casein powder is dissolved in the following
manner :—

Thirty parts of clean soft water are heated in a pan to

Fic. 17.—Werner & Pfleiderer’s Kneader and Mixer with Heated Trough.

about 176° F. and then poured into the kneading and mixing
machine shown in Fig. 17, which is fitted with an arrange-
ment for heating the trough. The stirrers having been set
in motion, 5 parts of casein powder are run in by degrees,
and in this way a uniform solution is obtained. It will not
do to add too much powder at one time or to put the casein
into the trough before the water, or a lumpy mass will be
obtained instead of a thin homogeneous solution. The warm-
ing of the trough throughout the operation will prevent the
solution thickening too soon,

SUNDRY APPLICATIONS OF CASEIN. 185

This solution is next applied evenly to the surface of the
stretched canvas. When the coating is dry the next step is +
to apply the priming composition—a mixture of neutral
wool fat, dissolved casein and the finest levigated chalk or
lithopone. Drying oils and dryers may also be added in
moderate amount if desired.

The neutral wool fat, which exudes from the glands in the
skin of the sheep, and constitutes the grease permeating the
wool, is met with in a purified state in commerce, as lanolin.
It differs from vegetable and animal fats inasmuch as the con-
tained fatty acids are not combined with glycerine, but with
cholesterin and the so-called fatty alcohols. As a result of
this constitution the fat is less affected by the influence of
warmth, air, and light than the other fats of animal or vegetable
origin. It remains perfectly sweet even after prolonged ex-
posure to atmospheric influences, and unlike the true fats it
shows no increase of acidity and no rancidity with increasing
age. Another consequence of the peculiar composition of
neutral wool fat is its high resistance to the action of alkalies
and caustic alkaline earths, so-that, under ordinary conditions,
it is unsaponifiable. The neutral wool fats are miscible with
water, and are able to absorb and permanently retain up to
as much as twice their own weight of water—a valuable
property when the incorporation of large quantities of water
into a fatty mixture is desired. As a rule the neutral wool
fats are among the most stable fats known, and their valuable
qualities ensure them a progressively extending industrial
future.

The elasticity and resisting properties of the mixture of
casein and neutral wool fat render this composition specially
adapted for grounding artists’ canvas.

Another composition, suitable for photographers’ back-
grounds, is obtained by mixing cement or diatomaceous earth
with casein solution, In this case also the durability of the

186 : CASEIN.

priming can be increased by spraying it with a dilute solution
of formaldehyde.

In the case of canvas for other decorative purposes, the
power of resisting the action of the weather is a prominent
necessity. The priming for this purpose may be prepared
by stirring 18 parts of chalk and 24 of earthy pigment to a
pulp with water. Ten to 14 parts of casein previously treated
with alkali are next stirred in, and the whole is diluted with
another 10 parts of water.

For priming canvas for outside exposure, the following
method is recommended: 10 parts of finely powdered casein
soluble in water are intimately mixed with 10 parts of slaked
lime and 90 of levigated chalk, and diluted with water to
workable consistency.

Solidifying Mineral Oil.—Casein and formaldehyde are
especially useful in the solidification of petroleum and other
mineral oils. The oil is treated with dissolved casein or
an alkali compound of the same. According to Helbing &
Passmore’s Patent Specification, the resulting compound is
hardened with formaldehyde, and is then insoluble in water ;
it does not melt on heating, but the petroleum can be re-
covered by distillation. ‘The product is similar in colour to
the petroleum used, but is less transparent.

Uses of Casein in Photography.—In connection with the
employment of casein as a medium for photographic purposes,
Dr. Otto Buss expresses himself in the following terms :—

When we consider the integral character of the medium
as a factor of sensitised strata in photography generally, and
especially in silver chloride printing-out papers, and the part
it plays in the presence of silver salts of organic acids, as
well as the extent to which it influences the print and the
character of the photographic picture, we cannot regard as
useless any endeavour to attain perfection by the use of fresh
substances as media, Just as 1t would be erroneous to rest

SUNDRY APPLICATIONS OF CASEIN. 187

content with what has been already attained in this direction,
and to regard it as settled beyond question that the known
media—albumen, gelatine, collodion, vegetable albumen,
algin jellies, rosin, starch, etc.—fulfil all requirements, and
afford sufficient méans for the manifestation of the indi-
viduality of the photographer in the production of artistic
effects, so also is the prospect certain that the means of
artistic expression and technical advantages in photography
can be widened by the adoption of new substances as media.

Among the numerous colloidal amorphous substances
whose chemical and physical properties indicate the prob-
ability of their application as photographic media, a place
almost in the front rank must be given to casein, which has
already formed the subject of investigation for this purpose
by various photographic chemists. Their experiments have
remained unsuccessful, owing to the difficulty of overcoming
the technical imperfections of casein strata for photographic
purposes to an extent that could make their advantages
apparent. 7

So far as these experiments have been made public and
brought to the writer’s knowledge, they were all undertaken
with the object, mutatis mutandis, of dissolving casein in
alkalies and employing this solution, together with the
requisite quantity of chlorides to ultimately form silver
chloride, to coat paper for sensitising with silver nitrate.
These attempts, therefore, were directly allied to the albu-
men process, under the erroneous idea that casein being an
albuminoid substance, would behave similarly to egg albumen.

The writer has repeated and checked a number of these
experiments, and found it impossible to obtain papers of
practical utility by the method in question. Pure casein
was dissolved in alkalies, with the aid of warmth, both caustic
alkalies (potash, soda, and ammonia) and carbonates (sodium
carbonate and bicarbonate) being used, the casein being

188 CASEIN.

stirred up with water and brought into solution by adding
the dissolved alkalies. In some cases the resulting solutions
were treated with common salt or ammonium chloride and
filtered, so that uniform glossy layers could be obtained on
papers, either plain or surfaced with baryta. Flexibility was
readily obtainable by the addition of glycerine to the casein
solution. The dried papers were then sensitised in the usua]
way, both in neutral silver baths and in those containing
citric acid. Nevertheless, although the conditions were
varied in numerous ways, and the papers resembled albumen
papers in many respects, the film softened, either occasion-
ally in the toning bath or invariably in fixing or washing,
and in some cases came off altogether, though this could
be prevented by using an alum bath before fixing. Some-
what better results were obtained by using casein solutions
hardened with formaldehyde, inasmuch as the papers then
could be toned, fixed, and washed. The papers had the same
general character as albumen paper, without any advantages
over the latter. When sensitised, even in an acid bath, their
keeping properties were very poor, which, indeed, is not
surprising in view of the presence of the formaldehyde, which
is a reducing agent. Further attempts in the same direction
were abandoned as hopeless ; and those made with a view to
using casein in the preparation of emulsions proved equally
unsuccessful, a compound containing silver and casein being
invariably separated in large flakes, impossible to divide
sufficiently fine by mechanical means. These experiments
were also abandoned ; and although it is not asserted that the
use of alkaline solutions of casein in one or other of these
directions is an impossibility, it would seem that some
technical device of a very different character to the usual
methods of working will have to be adopted to ensure
success ; in any case, the writer does not at present think
it likely that a normal practical method will be discovered,

SUNDRY APPLICATIONS OF CASEIN. 189

An explanation of the peculiar behaviour recorded above
is afforded by the chemical conduct of casein. The sub-
stance may be regarded as having both basic and acid
properties, since it is insoluble in water, alcohol, ether, ace-
tone and other known solvents, whilst it furnishes compounds
with both metals and acids. The alkali compounds are
readily soluble in water, whilst the compounds with the
heavy metals, such as iron, copper, silver, etc., are precipi-
tated as insoluble, amorphous, flocculent precipitates from the
solutions of the alkali salts, on addition of soluble salts of the
metals.

The basicity of casein is revealed by the fact that it
dissolves to form an acid solution when stirred up with water
and carefully treated with a dissolved alkali, whilst, after
neutrality is reached, a further quantity of alkali can be.
added before the same appears in excess, that is to say,
before the appearance of an alkaline reaction can be detected.

The alkali compound wall therefore act as a dibasic salt
in presence of silver nitrate, normally with the formation
of a silver compound (presumably containing two atoms of
silver) and alkali nitrate; and this will invariably occur, no
matter in what manner the casein and alkali are brought
into solution. Silver caseate, however, is by far inferior in
stability to silver alouminate, inasmuch as the silver caseate
image is soluble in hypo.

On the other hand, casein dissolves in dilute acids, from
which solution it can be reprecipitated ‘by neutralisation
with alkali, without. decomposition. The same precipitate
is obtained by the use of a large number of metallic salts,
such as alkali chlorides, alkali sulphates, alkali nitrates, a
number of salts of the heavy metals, etc. ; and this peculiarity
seemed to the writer to offer a prospect of success in using
casein as a medium for photographic films.

_ The success foreshadowed was eventually realised in the

190 | CASEIN.

following manner: When casein is stirred up with water
and dissolved in a weak solution of acid, e.g., citric acid, by
gentle heat, it forms a clear, gelatinous mass, which sets to a
jelly on cooling. Physically, it behaves exactly like gelatine,
and there is not the least difficulty in coating paper uni-
formly with the warmed solution. The coating sets im-
mediately, forming a glossy stratum, which, however, is
still slightly soluble in water. To render it insoluble in water
and weak acids, it is treated by floating or immersing the
paper in a solution of common salt or ammonium chloride,
etc., and this treatment does not deprive the stratum of its
permeability to aqueous solutions. At the same time, the
use of a chloride in this operation imparts to the stratum
the chloride necessary for the subsequent formation of silver
chloride, without eliminating the citric acid. It is easy, by
suitably modifying the concentration of the chloride solu-
tion, to incorporate any desired quantity of chloride in the
stratum; and since, as already mentioned, the original
quantity of citric acid is left unaffected, or only washed
out to a very slight extent by the chloride solution, it is
possible in this way to adjust the relative proportions of
chloride and citric acid to any desired extent. The paper
prepared in this way will, of course, keep for any length of
time when dry. Sensitising is effected in the same way as
for albuminised paper, in a neutral or faintly acid silver
bath; but the processes involved in the operation are
evidently of a very different character to those occurring in
the case of albuminised paper, or such as that prepared with
an alkaline solution of casein. It does not seem probable
that insoluble, free casein and silver nitrate react with
formation of silver caseate and nitric acid; besides which
both the behaviour of the finished paper and the results of
wet tests are against the occurrence of this reaction. The
reaction is more probably confined to the silver nitrate,

SUNDRY APPLICATIONS OF CASEIN. 191

the chloride and the citric acid alone, silver chloride and
citrate being formed in the casein stratum, which itself
remains chemically unaltered. The behaviour of the stratum
in every respect favours this assumption, which is very
difficult to prove chemically, both the casein and silver
caseate being insoluble; for whilst the stratum cbtained by
means of casein, alkali and silver nitrate is soluble when the
print comes to be fixed in hypo, etc., that obtained in the
manner just described remains perfectly intact and tough.
The typical purple-brown colour of silver caseate could not
be detected anywhere, the print having the same bluish or
reddish-purple tone as the gelatino-chloride or collodio-
chloride papers. At the same time, the character of the
prints more nearly resembled that of gelatine papers than
albuminised papers. Alkali caseates and the water-soluble
egg albumen of albuminised paper, on the other hand, react
on silver nitrate to form silver albuminate and silver. caseate
respectively. (An analogous reaction may be mentioned in
the behaviour of citric acid and silver nitrate, inasmuch as
alkali citrate and silver nitrate furnish silver citrate in almost
quantitative amount, whereas none is formed in the case of
the free citric acid and silver nitrate.)

In this manner the utilisation of casein as a medium for
photographic films may be cldimed to have been accom-
plished, inasmuch as a stratum of free casein is obtained
which encloses the image-forming substances, silver chloride
and silver citrate. The use of this method should certainly
not be restricted to the preparation of chloride printing-out
papers, but will probably find application in numerous other
‘directions.

By using iodides to precipitate the casein it should be pos-
sible to obtain, by sensitising in an acid bath, silver iodide
pellicles suitable for chemical development ; whilst the use of
bromides would furnish silver bromide pellicles.

192 CASEIN.

Casein stirred up in water can be dissolved in any weak
acid by gentle heat, furnishing a hyaline, gelatinous solution.
This solution poured over a glass plate, celluloid film, paper,
or the like, while warm, will set on cooling and dry with a
brilliant gloss. The dried film, which is still slightly. soluble
in water, may be floated or immersed in a solution of any
metallic haloid, and thereby rendered insoluble, a sufficient
quantity of the haloid salt for the formation of the silver
haloid being incorporated in the casein stratum at the same
time. Chlorides, bromides, and iodides, or mixtures of the
same can be used in this way. The resulting stratum is as
tough as leather, whilst permeable to liquids, and it can be
rendered as flexible as desired by adding glycerine. It may
be sensitised by a neutral or faintly acid solution of silver
nitrate, inasmuch as this latter reacts on the metallic haloid
in the stratum, to form the corresponding silver haloid.
According as the casein has been fixed with chlorides or
bromides, ‘the product will be either a faintly sensitive
‘chloride printing-out casein stratum or a highly sensitive
bromide stratum suitable for development. The method,
which is specially adapted for printing-out papers, is patented.
These papers, which may be advantageously prepared by the
aid of baryta, exhibit several valuable properties, which fill a
long-felt want in practice. ?

They print fairly rapidly, in agreeable tones, and are
easily toned in a sulphocyanide bath, which gives warm, pure
tones, free from double toning. Neutral combined toning
and fixing baths can also be used. Even in warm’ water
the stratum remains tough and leathery, without softening,
and it is perfectly flexible, so that the prints do not curl in
the bath. The finished prints resist mechanical influences
(scratching, rubbing, scouring, etc.) in a remarkable degree,
and their sensitiveness to light is thoroughly good. ‘The
prints show soft, delicate gradation, somewhat softer and

\

SUNDRY APPLICATIONS OF CASEIN. 193

with finer definition than albumen prints, without exhibiting
the hardness of gelatine or celloidin emulsion papers. Hence
the casein papers combine in themselves the pictorial softness
and the flexibility of the albumen papers, with the permanence
and improved definition, together with the extensive range
of toning methods enjoyed by the celloidin and gelatine
emulsion papers, without the tenderness and susceptibility to .
temperature of the latter, either in the wet or dry state.

Even if papers prepared in this manner cannot be intro-
duced into practice, the foregoing observations will serve to
indicate the way in which the most readily available albu-
minoid, casein, can be utilised as a medium for photographic
purposes.

Casein Ointment.—To prepare a drying ointment, pure,
dry, pulverised casein is dissolved in a mixture of equal parts
of dilute ammonia and glycerine. After heating the solution
until the ammonia has been expelled, the solution may be
mixed with fats to form an emulsion, which, when applied as
an ointment to the skin, soon dries to an elastic, cooling
layer.

Clarifying Glue with Casein.—According to Hewitt (New
York), glue can be clarified by the addition of casein, which
is afterwards thrown down by neutralisation (and heat, if
necessary), leaving the glue perfectly clear, free from fat,
colourless and inodorous.

Casein in Soapmaking.—The frequency with which casein
has been offered for use in soapmaking has drawn the atten-
tion of interested parties to the matter, and led to exhaustive
experiments to determine whether it is really suitable for this
purpose. :

In Austria the use of casein in soapmaking is protected
by Letters Patent. The process 1s a development of the
well-known milk soaps; and, just as an addition of cows’

milk is considered to be an improvement in these soaps, so
13 :

194 CASEIN.

also, to some extent, is the use of casein in toilet soaps, since
it can hardly be regarded as merely an adjunct designed to
load or cheapen the product, except, perhaps, to a very
restricted extent. From the practice of working up cows’
milk into toilet soap to the use of casein for the same
purpose is but a step. Then, again, it has been proved that
toilet soaps containing casein have behaved better than those —
without such addition, and also that the casein added has a
beneficial effect on the perfumes used, rendering their odour
more pronounced and fixing them to some extent. More-
over, albuminoid washes have a beneficial effect on the skin,
so that the use of casein seems commendable.

Casein being insoluble in water, it must first be brought
into solution by combining it with alkalies such as borax,
calcined soda, sodium bicarbonate or caustic soda.

In places where ample supplies of moist casein are avail-
able to the soap-maker, the method of incorporating it is fairly
simple. The casein is placed in a pan fitted with stirrers,
and dissolved in one of the aforesaid alkali compounds, with
constant stirring, the solution being added to the finished
soap. .

To bring commercial dry casein into suitable condition
for the same purpose it must be mixed with water containing
the requisite alkali in solution. Casein thus treated will
absorb large quantities of water, and it is on this property
that its use as a method of cheapening soap is based. This
applies more to curd soaps than to toilet soaps, especially
when the Schnetzer moulding machine or the Klumpp
cooling. press is used. In the case of toilet soaps, 7.¢., stock
soaps for milled soap, such a large proportion of the moisture
evaporates in the drying apparatus that the amount is reduced
to about one-third, though it is still worthy of note in view of
the other advantages presented by the use of casein.

As already stated, the casein is intimately mixed with the

SUNDRY APPLICATIONS OF CASEIN. 195

aqueous solution of alkali. The resulting, somewhat sticky
mass, however, must not show an alkaline reaction towards
phenolphthalein, though, nevertheless, all the casein must be
in suspension. Even during this stage of the operation a
strong smell of ammonia will be noticeable, and this increases
when the mass is introduced into the hot soap. At the same
time the liberation of carbonic acid is stimulated by the heat,
therefore care must be taken that the soap does not rise and
run over the top of the pan.

Another advantage of casein soaps is their greater lather-
ing power, which is peculiarly desirable in the case of shaving
SOaps.

For these reasons Antony recommends all soap-makers to
give casein a trial, since it will probably prove useful in some
cases.

Casein-albumose Soap.— This soap is prepared from
tallow and olive oil by saponification with a mixture of
caustic soda and caustic potash. After salting-out with
potassium chloride, a preparation of casein and albumose is
incorporated with the soap, which is then superfatted to the
extent of 7 per cent. This soap may be used in place of
casein ointment.

Eberhardt and Mierisch’s Soluble Casein.—A perfectly
soluble, fat-free casein can be obtained by centrifugalising
skim milk at about 104° to 113° F., treating it with caustic
potash or soda, passing it through the separator again until
no more fat is eliminated, and then precipitating the casein
by means of an acid, ¢.g., dilute sulphuric acid, or better still,
by an acid forming soluble lime salts, such as ethylsulphuric
acid, lactic acid or acetic acid. The precipitate is washed an
dissolved in a solution of alkali. The entire process is then
repeated several times, the casein being finally dissolved in
ammonia, treated with benzine or chloroform to extract fat,
and then filtered through diatomaceous earth or the like.

196 CASEIN.

The resulting solution may be used per se or again treated
with an acid to throw down the casein.

Waterproof Casein.—When a 5 per cent. sehation of
casein in alkali is mixed with formaldehyde no coagulation
occurs, the solution remaining clear and fluid for a long time.
If this solution be poured out on a sheet of glass, zinc, paper,
etc., or left to dry, an insoluble film of casein is obtained.

Another way is to prepare a solution containing about
100 parts of casein and 14 parts of caustic soda in 1,000 of
water, to which 15 parts of a 40 per cent. solution of formal-
dehyde are then added. This mixture, which remains per-
fectly clear, is next poured out on a sheet of glass, zinc, or
paper and evaporated or dried. ‘In order to produce a water-
proof film from an ammonia solution of casein, a solution is
prepared containing about 100 parts of casein, and 10 parts
of a 10 per cent. solution of ammonia, in 2,000 parts of water.
About 30 parts of a 40 per cent. solution of formaldehyde are
added, and the casein is dried as stated above.

This waterproof casein may be used in various industries,
for instance, photography, papermaking and the preparation
of surgical bandages.

CHAPTER XII
CASEIN COMPOUNDS.

In view of the extensive general application of casein it is
not surprising that many attempts have been made to obtain
compounds of this substance with chemical elements, for a
variety of purposes. In addition to those already described
are a number of others, which, together with their mode of
preparation, are given below.

To prepare compounds of casein with iodine the two sub-
stances are intimately mixed and warmed. The resulting
products are used in medicine (German patent 79,926).

Dr. Bernstein prepares albumose and peptone from milk
casein by bacterial agency.

Solid compounds, soluble in water, are obtained from
casein with hydrobromic and hydriodic acids of medium
strength by stirring the substances together ; or by dissolving
the casein in the dilute or concentrated acid (German patent
124,232, 1900), and precipitating the resulting casein com-
pound. In therapeutic vdélue these compounds are inter-
mediate between the metallic bromides or iodides and the
corresponding free acids.

According to J. Just’s American patent of February 4,
1902, a casein phosphate can be prepared by adding to an
aqueous solution of phosphoric acid a portion of the necessary
quantity of casein, heating the mixture and concentrating it
to syrup. The remainder of the casein is then added and

well mixed with the mass, which is finally dried.
(197)

198 CASEIN.

A medicinal food is prepared by the patent process of the
Chemische Fabrik Rhenania, in which a solution of casein
in very weak phosphoric acid is precipitated by a primary
phosphate, the precipitate being freed from the excess of
acid by washing with a solution of the same phosphate.

With salicylates casein forms soluble compounds, which
are applicable in therapeutics owing to the readiness with
which they are absorbed and the slight irritation which they
cause to the mucous membrane of the stomach.

To prepare water-soluble compounds of casein with
alkaloids, the latter—in alcoholic or other solution—are
allowed to act on dry or moist acid-free casein.

According to Knoll & Co.’s patent, compounds of casein
with an organic acid containing phosphorus and nitrogen
are obtained by digesting casein with pepsin chloride, neu-
tralising the filtrate with sodium carbonate, and treating it
with iron-ammonium alum. On heating, the iron compound
of casein separates out. This iron salt is soluble in the
intestinal juices.

Soluble compounds of casein with lithiwm salts form the
subject of a patent by C. Wendt, of Stollberg. _

To prepare compounds of casein with heavy metals
such as mercury, silver, and tron, solutions of neutral alkali
casein are treated with salts of mercury or silver, and pre-
cipitated with alcohol or concentrated in vacuo. According
to an additional patent of the @hemische Fabrik Pfersee,
Augsburg, the albumen compound may also be suspended in
alcohol or acetone and boiled with aqueous or alcoholic
solutions of the heavy-metal salts. The mercury-, silver-,
and iron-compounds thus obtained possess properties which
seem to render them useful, both technically and medi-
cinally.

Among the silver compounds of casein Roéhmann and
Hirschstein have discovered a product, which they term

CASEIN COMPOUNDS. 199

‘‘argentumcasein’”’. This is able to form salts and contains
silver in complex combination, not as an ion. According to
Imray’s patent, a solid silver-casein compound of this kind,
which does not furnish any precipitate when its aqueous
solution is treated with albumen or salt, is obtained by
mixing a solution of silver nitrate or other salt of silver
with a neutral solution of an alkali casein, and evaporating
the mixture to dryness in vacuo.

Compounds of arsenic and casein are prepared in the
same way as those of the heavy metals, and are also used

medicinally.
| Alkali salts and the potassium salt of casein are obtained
as dry powders by concentrating, 7m vacuo, solutions of casein
in caustic alkalies, alkali carbonates, sodium phosphate or milk
of lime.

The Casein Company of America (U.S. patent 717,085)
prepares a casein compound which forms a thin solution
with a relatively small quantity of water. This is effected
by incorporating oxalates with casein, for instance, 2 parts of
potassium oxalate and 15 of powdered borax to 100 of dry
casein, the whole being thoroughly mixed. ;

A subsequent patent relates to the production of oxidised
casein by dissolving an oxidising agent in about its own
weight of water, and then rapidly stirring in the casein to
ensure intimate mixture. Ammonium persulphate is the
oxidising agent preferably used. Oxidising agents, however,
cause more or less decomposition in casein.

An insoluble casein compound is prepared, according to
B. Dunham’s patent, by mixing about 15 parts of borax and
85 of commercial casein, dissolving this in 400 parts of
water, treating the solution with about 15 parts of hexa-
methylene-tetramine and leaving the liquid to evaporate, the
dry product being then exposed to heat and moisture. ‘The
preparation is suitable for replacing egg albumen.

900 | CASEIN,

Kalle & Co. (Biebrich) have patented a process for pre-
paring compounds of Acrolein with starch, dextrin, gums, or
proteids, ¢.g., casein, for therapeutic purposes. |

Casein acts as a weak acid forming salts which are
neutral toward phenolphthalein, but alkaline towards litmus.
By Liebrecht and Rohmann’s patented process not only are
these neutral lime and sodium compounds prepared, but also
solid casein compounds of alkalies and alkaline earths, with an
acid reaction.. For this purpose the acidity of the casein is
first determined with phenolphthalein. To prepare a neutral
compound the casein is dissolved in the calculated quantity
of alkali; for an acid compound half the quantity is employed, |
and the solution concentrated in vacuo. The resulting
neutral compounds are well adapted for painting, whilst the
compounds acid to phenolphthalein are of special importance
for dietetic and similar purposes.

L. L. Van Slyke and EK. B. Hart! prepared pure casein
almost free from mineral matter by precipitating with an
acid and repeatedly washing with water. This product
became plastic on warming and readily dissolved in a 5 per
cent. solution of sodium chloride, and also in 50 per cent.
alcohol on warming. From this casein a basic calcium-
casein was prepared containing 2'4 per cent. of lime and
also a neutral calcium-casein containing 1°5 per cent. of lime.

Paracasein free from bases was also obtained by adding
ammonium oxalate to skim milk filtering, acting upon the
filtrate with rennet for two hours and then precipitating with
hydrochloric acid. The product was dissolved in lime water,
and from the solution basic calcium-paracasein, containing
2°4 per cent. of lime, and neutral calcium-paracasein, con-
taining 1'5 per cent. of lime were prepared. These compounds
also dissolve in a solution of common salt and in 50 per cent.

1“ New York Expt, Stat, Bull.,” 1905, 26, 1-37.

GASEIN COMPOUNDS. 901

alcohol, and are regarded by the authors as identical with
the casein compounds.

The ammonium compound and the hydrochloric acid com-
pound of casein can be prepared (German patent 84,682)
-direct in the solid form by passing gaseous ammonia or hydro-
chloric acid over finely powdered dry casein ; or by suspending
the latter in some liquid (e.g., alcohol, ether, ligroin or benzol)
in which it is practically insoluble, and treating it with one
or other of the above-mentioned gases. The resulting com-
pounds are in the form of white powder, stable in air, and
dissolve to a clear, almost tasteless, solution in water. :

The feature of Dr. Dojen’s process: for preparing a com-
pound of casein and formaldehyde is that pulverised casein is
digested with formaldehyde, then dried, treated with dilute
caustic alkali and digested for a long time at ordinary tem-
perature with a concentrated solution of formaldehyde. ‘T'he
product has the bactericidal properties of formaldehyde with-
out its irritating action.

According to German patent 98,177, a dilute aqueous
solution of sodium or other glycerophosphate is mixed with
an excess of casein at a temperature of 30° to 40° C.; and after
standing for twelve hours, the filtrate is concentrated in vacuo
at 40° to 50° C.

THE END.

cia
Gy

hae

INDEX.

A.

Acetic acid, 52.

— — action of, on casein, 47.

—-— — — — milk, 17.

— — as a coagulant of milk, 17, 30.

— — for souring milk, 17, 30, 34.

— casein, 43.

Acetone, 156,

Acid, acetic, 52.

— amido-oenanthylic, 52.

amido-propionic, 52.

aspartic, 52.

casein, 42,

— compounds, 189, 200. :

diamido-trihydroxydodecanic, 52.

from milk sugar, 17.

glutamic, 52.

lactic, 5, 7, 15, 16.

— formation, 16.

oxalic, 52,

properties of casein, 44, 189, 200.

sulphuric, action on milk, 17.

— sulphurous, 52,

Acids, action of, on casein, 46, 47.

— — — — milk, 15.

— adsorption of, by casein, 46.

— organic, casein compounds with,

198,

Acrolein compound with casein, 200.

Adhesive, Crosspietsch’s, 107,

— Jeromin’s, 108,

— solid, 112.

Adhesives, casein, 104-120.

Adsorption of acids by casein, 46.

Albert and Berend’s patent condensa-
tion product of casein, phenol and
formaldehyde, 146.

Albumen, Riegel’s milk, 161.

Albumin, analysis of, 42,

— as a food, 158.

Albuminoids and casein, ss on
fibres, 132,

Albumose, Dr, Bernstein’s, 197.

— casein soap, 195. ©

Alexander on rennet, 10.

Alkali compounds of casein, 189.

Alkali salts of casein, 199.

Alkalies, action on casein, 45, 138.

— as casein precipitants, 189,

— — solvents for casein, 91,

Alkaloids, casein compounds with, 198.

Al secco painting, 98.

— sgraffito painting, 98.

Alum, 39, 40, 49, 88.

Aluminium acetate in casein masses,

125.

American casein factories, 1, 39.

Amido-oenanthylic acid, 52.

Amido-propionic acid, 52.

Ammonia, action of, on casein, 32.

Ammonium caseate, 45.

— casein compound, 201,

— persulphate, action of, on casein,
199.

— sulphate as a casein precipitant, 51,
156.

Analysis of albaititn, 42,

— — casein, 42, 56, 66.

— — — paint, 66. ~

— — fibrin, 42.

— — industrial casein, 56.

Anti-corrosive composition, 124.

Anti-radiation composition, 124.

Application of casein paint, 87, 93.

Applications of casein, 167-196.

Argentine, 150.

*¢ Argentumeasein,” 199.

Arginine, 52.

Arsenic compounds
casein, 34, 105.

— casein compound, 199.

Artificial horn, ivory, etc., 125.

Artists’ canvas, priming, 182.

Asbestos in casein masses, 124.

— paper, waterproof, 172.

Aspartic acid, 82.

Asses’ milk, casein from, 43.

B.
Baechler’s patents for preparing casein,

39, 40.
‘* Baekelite,” 146,

as adjuncts to

203

204

Bacillus acidi-lactici, 17,

Bacterium lactis, 17.

Bags, paint for marking, 84,

Baking preparation, Bernstein’s, 164.

— casein phosphate for, 164,

Balsams in casein paint, 92.

Bang on rennet, 9.

Barium chloride as casein peephapant
114,

Barnodai’s plastic mass, 133.

Barrels, paint for marking, 84.

Bartel’s patent horn-like, composition,
128, 129.

Basicity of casein, 189.

Beissier on casein tempera, 98,

Bellamy’s patent for producing casein
glue, 34.

Bernstein’s albumose, 197.

— baking preparation, 164,

— patent cement, 115,

— — for casein glue, 114.

Berzelius on rennet, 8.

Bessana’s method of preparing casein,
35.

Beuse’s shoe polish, 178,

Bimbi on nutrium, 162.

Bind for meerschaum, casein, 116,

Binding medium, compounding the,
87, 91.

Black casein paint, 68, 69, 77, 78.

Blocks, casein, 156,

‘ Blood albumen, 60, 107.

Blue casein paint, 68, 73, 74, 77, 78.

Boards, washable cement for, 118,

Boerman’s patent plastic mass, 132.

Boiled oil substitute, 78, 80.

Bolder’s liquid casein glue, 107,

Bone, imitation, 125.

Borax and casein cement, 117.

— — — glue, 111.

— as a casein solvent, 91, 117.

Boxes, casein glue for, 113.

Bread from flour and curd, 165. —

— low in carbohydrates, 165.

Bromine compounds with casein, 197.

Brown casein paints, 76, 77.

Brunstein’s patent casein paint, 80.

Brushes for casein paint, 95.

Buffalo milk, casein from, 43.

Buss on casein in photography, 186.

Buttermilk, casein from, 28,

Butylamine, 52.

C.

Calcium caseate, 44, 45.
— hydroxide, 63, 70.

CASEIN,

Calcium salts, action of, on rennet cé-
agulation, 44, 51,

— tannate, 105.

Calico printing, casein medium for,

155.

Calsomine wash, 79.

Camphor in casein putty, 116.

— celluloid substitute, 135. |

Canvas, preparation of artists’, 182.

— priming for, 186.

Carbonate of potash and soda for casein

cement, 106.

Carmichael’s dressing preparation; 151.

Carnauba wax, 179.

Cardboard boxes, casein glue for, 113.

Caseate, ammonium, 45,

— calcium, 45,

— silver, 189, 190.

Casein, acetic, 43.

— acid, 42.

— compounds, 189, 200.

action of acids on, 46, 47,

— — alkalies on, 45.

— — formaldehyde on, 53-55.

adhesives and putties, 104-120,

adhesive, solid, 112.

— Jeromin’s, 108.

adsorption of acids by, 46,

albumose soap, 195,

alkali compounds, 189. ©

analysis of, 41-43, 56, 66,

— — industrial, 56.

and albuminoids, fixing on fibres,
132.

— borax cement, 117.

— — glue, 111,

— formaldehyde, cask glaze, 180.

— lime cement, 118,

— water-glass cement, 117.

artificial horn from, 125, 128, 130.

as a substitute for egg albumen, 163.

bind for meerschaum, 116,

blocks, 156,

cellulose composition, 133,

cement for glass, 116, 117,

— — metals, 117.

— — porcelain, 116, 117.

— — stone, 119,

— paint, 85,

— Wenk’s, 118.

cements, 116, 117.

clarifying glue with, 193.

clear, non-milky, 138-141,

colour lakes, 84.

commercial, 41.

Company of America, 110, 113, 156.

— celluloid composition, 132.

— oxalate, 199.

INDEX.

Casein Company, solution, 199.
— composition, Morin’s patent, 128,
— — of, 5, 41-57.
compound, Dunham’s patent, 39.
— Revis, Bolton, and Bacon’s
patent, 114.
—- soluble, 114.
compounds with :—
Acrolein, 200.
Alkali, 199.
Alkaloids, 198.
Ammonium, 45, 201.
Arsenic, 199,
Bromine, 197,
Calcium, 45.
Citrates, 165.
Copper, 189.
Formaldehyde, 201.
Glycerophosphates, 160, 201.
Hydriodic acid, 197.
Hydrobromic acid, 197.
Hydrofluoric acid, 156.
Todine, 197.
Tron, 189, 198.
Lithium, 198.
Mercury, 198.
Phosphoric acid, 197.
Potassium, 199,
. Salicylates, 198.
Silver, 189, 198.
— decomposition products, 52.
— dissolving, 32. ;
— distemper paints, 75.
— dressing for linen and cotton fabrics,
149.
— Dr. Schreiber on, 162.
— drying, 36.
Kilersen’s patent for preparing, 28.
emulsifiable, 164.
emulsion of, 92.
enamel paint, 67.
estimation of, 55.
facade paint, 67.
— food, 162, 165.
— Higgins’, 165.
foodstuffs, 158-165.
for colour printing, 147-157.
— finishing purposes, 147-157.
— mending glass, 116.
— mercerised crépe, 153.
from asses’ milk, 43.
— buffalo milk, 43.
— goats’ milk, 43.
— — human milk, 43,
— mares’ milk, 43.
— sheeps’ milk, 43.
glue, 106, 114.
— Bellamy’s, 105.

_
—

205

Casein glue, Bolder’s liquid, 107.

— for cardboard boxes, 113.

— — match making, 115.

— — mending glass, china, etc.,

112.

— Hall’s, 109.

— in plates and flakes, 107.

— liquid, 110.

— powdered, 111.

gum, 104.

— Hall’s method of preparing, 30.

— — patent for coating paper, 170.

— Hoppe-Seyler method of preparing,
35.

—

!

— Horn’s clear solution, 170.

— horny mass, 130.

hydrolysis of, 52. ©

in photography, 186.

— sheets, blocks, etic., 156.

— soapmaking, 193.

insoluble, 120, 145.

insolubility of, 102, 147.

in textile industries, 147-157.

Just on preparation of, 123.

lime colours, 69, 72.

magnesia, 155.

manufacture, 3-40.

mass, horny, 130.

medium, 92, 97.

— for calico printing, 155.

Mierisch and Eberhardt’s process
for preparing, 33.

molecular weight of, 44.

Nagel on vegetable, 29.

ointment, 193. e

origin of, 3.

oxalates, 198.

oxidised, 199.

paint, 81.

— and varnish, 72.

— Brunstein’s patent, 80.

— older method, 65.

— preparation and application of,

87, 93.

— quick drying, 79.

— sundry recipes, 66.

— value of, 99.

painting, technics of, 87-103.

paints, 58-86.

— for walls, 73.

— — woodwork and iron, 73.

— storing, 95.

phenol and formaldehyde conden-
sation product of, 146.

phosphates in baking, 164, 197.

photographic plates, 179.

— plastic masses, 121-146,

'|— plates, joining, 113.

206

Casein powder, 106.

— precipitation of, 10.

preparation of 3, 4-40.

properties of, 3, 6, 41-57.

putties, 104-120.

— Lehner’s, 115.

rennet, 42,

Ricard and Riche’s patent, 39.

— Riegel’s method of preparing, 33.

Ruprecht on preparation of, 31.

Schreiber on, 162.

shoe cream, 179.

silicate paints, 75, 78.

sizing paper with, 168.

soda cement, 118.

solution, 113.

— for coating paper, 170.

solvents of, 91.

Spitteler on, 31.

Spitteler’s patent, 138- 141,

steam pan for, 12.

stopping, 119.

sundry applications, 167-196.

Szekeley’s method of preparing, 34.

technical, 37.

threads, blocks, plates, etc., 156.

titration of, 48.

uses of, 1.

— in the paper industry, 167.

— — — textile industries, 147-157.

various methods of preparing, 30-40.

varnish, 81.

vegetable, 29.

Caseinogen, 49.

Caseogum, 104, 108.

Cases, paint for marking, 84.

Cask glaze, casein, 180.

Celluloid, and galalith comparative
tests, 143.

— fireproof substitute, 134.

— imitation, 135.

— plastic mass, 132.

— substitutes, 133-135.

Cellulose casein compound, 133.

Cement, Bernstein’s patent, 115.

— — and borax, 117.

— — lime, 118.

— — soda, 118.

casein, 116.

— and waterglass, 108, 109.

for deal boards, 118.

— glass, 116, 117.

— metals, 117.

— porcelain, 116, 117.

— — stone, 119.

— outdoor, 90.

— paint, casein, 85.

— plaster, treating, 88.

—_—

- CASEIN.

Cement, Wenk’s, 118.

— white Portland, 90.

— Wittkowski’s, 115.

Centrifugal machines, 18-20.

Chalk, 62 70. .

— white casein paint, 73.

Champagne, whey, 16.

Cheese milk, composition of, 16.

Chemische Fabrik’s method of loading
silk, 156.

Chevalott’s waterproofing process, 155.

Chialiva and Dupot’s fixative, 98.

China bark as a casein precipitant, 105.

— casein cement for, 112.

— clay, 59, 70, 93.

Chlorine in casein paints, 81.

Chrome alum in casein glue, 107.

Citrates as casein solvents, 165.

Clarifying glue with casein, 193.

Clear, non-milky casein, 138-141.

— solution of casein, 170.

Clothing, paper wrappering for, 176.

Coating paper with casein, 170.

Cold glue, 104.

— water glue, 104.

— — paint in powder, 68.

— — paint, Ring’s, 81.

Collardon’s casein and viscose com-
position, 137.

Colour lakes, casein, 84.

— marble lime, 62.

— printing, casein for, 147-157.

Colouring matters, fixing insoluble, 152.

Colours, casein lime, 69.

— encaustic, 98,

— flag, 98.

— fresco, 98.

— Gobelin, 98.

— spike oil, 98.

— universal, 98.

Commercial casein, 41.

Compagnie Frangaise, a Celluloid, sub
stitute for celluloid, 133.

Composition of albumin, 42.

— casein, 5, 41-57.

cheese milk, 16.

fibrin, 42.

milk, 3.

whey, 16.

Cone paint mill, 67.

Copper casein compound, 189.

Cotton fabrics, casein dressing for, 149.

— — fixing zinc white on, 154.

Crosspietsch’s adhesive, 107.

Curd, bread from flour and, 165,

-— breaking, 18.

— draining, 20.

— drying, 20-25.

INDEX.

Curd glue, 106.

— mills, 18.

— purifying, 18, 25.

— rolls, Sell’s, 165.

— washing, 20.

Curds, 8, 15, 16.

Cutch as casein precipitant, 105.
Cylinders, drying, 20-23.

D.

Decomposition products of casein, 52.
Denne and Hentschel’s patent sizing
material, 157
Desgeorge and Lebriel’s
casein, 145.
— Lyons and Lebriel’s patent for imi-
tation horn, etc., 145.
Diamido - trinydroxydodecanic
52. 5
Dibasicity of casein, 189.
Dickmann’s covering for walls and
floors, 124.
Dissolving casein, 32.
Distemper paints, casein, 75,
Dojen’s casein -formaldehyde
pound, 201.
Draining curd, 20.
Dreher on casein colour lakes, 84.
Dressing, casein for linen and cotton,
149.
— waterproof, 153.
Dunham?’s insoluble casein compound,
199,
— patent casein and celluloid com-
position, 132.
food powder, 165.
for casein compound, 39.
— dissolving casein, 113.
— insoluble casein, 53.
— sizing material, 156.
plastic mass, 132.
Drying casein, 36,
— curd, 20-25.
— cylinders, 20-23.
— flue for casein, 36.
— properties of casein paint, 59.
— rooms, 20, 32.
Duplicator pan for casein, 12.
Dyeing, fixing casein in, 152.

E.

Eberhardt and Mierisch’s
casein, 195.

Ebony, imitation, 142.

Kborit Co.’s patent plastic mass, 127.

Egg albumen, casein substitute, 163.

insoluble

acid,

,

com-

—_—

soluble

207

Kilersen’s patent for preparing casein,
28.

Electricity in preparation of casein, 29.

Emulsifiable casein, 164.

Emulsion of casein, 92.

Enamel paint, casein, 67.

Encaustic colours, 98.

— styles, 98.

Ethylsulphuric acid as casein precipi-
tant, 33.

Eucasein, 45.

Eulactol, 160.

FP.

Fabrics, treating, 151.

Facade paint, casein, 67.

Facing for paper, 170.

Fat, wool, 185.

Fats, paper flasks for, 174.

Fehringer’s patent water-white casein
varnish, 81.

Fibres, fixing casein and albuminoids

on, 149.

— softening, sizing, and loading, 151.

Fibrin, analysis of, 42.

Fillings for casein masses, 121.

Filter press, 27.

Finishing textiles, casein for, 147-157.

Fireproot asbestos, paper and board,

172.

— celluloid substitute, 134.

— roofing pulp, 180.

Fixative, formaldehyde as, 98.

— for paintings, 97.

Fixatives for casein paint, 97.

Fixing casein on the fibre, 149.

— insoluble colouring matters, 152.

Flag colours, 98.

Flakes, casein in, 107.

Flasks, paper, for oils and fats, 174.

Fleischmann on whey, 16.

Floor covering, casein, 124.

Food, albumin as a, 158.

— casein, 158-166.

— medicinal, 198.

— milk, 163.

— paper wrappering for, 176.

— powder, 165.

Foodstuffs, casein, 158-166.

Formaldehyde, action of, on casein,

53-55.

as a fixative, 98.

casein cask glaze, 180.

— glue, 110.

— insoluble, 128.

— masses, 137-145.

— paint, 81, 82..

—

208

Formaldehyde, compound with casein,
201.

— fixing zinc white on cotton with,
154.

— in binding media, 110.

Formolactin paint, 82.

Franquet’s celluloid substitute, 135.

Fresco painting, dry, 90.

Frescoes, painting on canvas, 96.

G.

Galactogen, 159.

Galalith, 54, 187-145.

absorption of water by, 144.

and celluloid, comparative tests,
143.

— articles made from, 142.

— as substitute for jet, marble, ebony,
etc., 142.

elasticity of, 143.

hardness of, 143,

Hassak on, 143.

insulating properties of, 144.

low conductivity of, 144.

pigments for, 142.

preparation of, 137-142.

resistance to reagents, 144.

specific gravity of, 143.

uninflammability of, 144.

Gardner’s sifter and mixer, 61,

Gelatine, 137.

Generator, steam, 13.

Gerhardt’s fresco process, 88, 98.

Geselschap’s lime tempera, 99.

Glass, casein cement for, 116, 117,

— glue for mending, 112.

Glauber salt as a casein fixative, 152.

Glaze, cask, 180.

Glue, casein, 104, 106, 114.

— — and borax, 111.

— for cardboard boxes, 113.

— — match-making, 115.

— in plates and flakes, 107.

clarifying with casein, 193.

cold, 104.

— water, 104.

for mending glass, china, etc., 112,

in casein paints, 59, 75.

— liquid casein, 107.

— powder, 114.

— Renken’s method of using, 114.

— waterproof, 153,

Glutamic acid, 52,

Gluten, 104,

Glutin glaze, 148.

Glycerine, 137, 172.

Hi a ea Bs ON a Sa

eee AGS

CASEIN.

Glycerophosphates and casein com-
pound, 201,

Goats’ milk, casein from, 43.

Gobelin colours, 98.

Goldsmith’s patent
material, 128.

Green casein paints, 68, 73, 74, 77, 78.

Grey casein paints, 77.

Guttmann’s patent milk flour, 160,

1: 8

Hall’s casein glue, 109.

— patent for coating paper with
casein, 170.

— process for preparing casein, 30,

— synthetic milk, 163.

Hammarsten on precipitating casein,
35.

— on rennet, 8.

Hardening casein masses, 128,

Hassak on galalith, 142-144,

Hatmaker’s casein phosphate, 164,

— method of preparing casein, 164,

Haubold’s centrifugal machine, 19,

Heating pans for casein, 11-13,

Heat of combustion of casein, 51,

Heim’s argentine, 150,

Heintz on rennet, 8,

Hewitt on clarifying glue, 193,

Higgins’ casein food, 165,

Histidine, 52.

Hoppe-Seylermethod of making casein,

35.

thermoplastic

Horn, artificial, from casein, 125, 128,

Horn-like composition, 128, 129.

Horn’s clear casein solution, 170.

Horny casein mass, 130,

Hueffe on bacillus acidi-lactici, 17,

Human milk, casein from, 43,

Hydriodic acid, casein compound, 197.

Hydrobromic acid, casein compound,

197.

Hydrochloric acid, casein compound,

201 :

— — for souring milk, 30,
Hydrofiuoric acid, 39.
Hydrolysis of casein, 52,

8
Imitating Pompeian wall paintings,
90

Imitation bone, 125,

— ivory, 122.

— leather, 125.

— linoleum, 125.

Industrial casein, analysis of, 56,

INDEX.

Insoluble casein, 120, 145.

— — compound, 199,

— colouring matters, fixing, 152.
Insulating preparation, casein, 127.
Introduction, 1

Todine casein compound, 197.

Iron barrels, paints for marking, 84.
— caseate, 189, 198.

— casein compound, 189, 198.

— — paints for, 73.

— rosinate, 178.

Ivory imitation, 122, 128,

J.

Jannin’s method of producing plastic
masses, 136.

Jeromin’s casein adhesive, 108.

Jet, imitation, 142.

Joining casein plates, 113.

Jolles on albumin substitutes, 158.

Jung, Brecher and Kittel’s insulating
preparation, 123,

Just on preparing casein, 38.

Just’s patent casein phosphate, 197,

K.

Kagenek’s casein and gelatin com-
pound, 137.

Kalle & Co.’s acrolein casein com-
pound, 200.

Kathe’s patent plastic masses, 131.

Kay and Schoen’s method of fixing
zinc white, 154,

Keratin and casein plastic mass, 127.

Kieselguhr in binding medium, 92.

Kirchner on milk, 8.

Kistory’s casein paint, 72,

Knoll & Co,’s patent casein oxalic
acid compounds, 198,

L.

Lactalbumen, 5, 15.

Lactarin, 37, 159.

Lactic acid, 15, 16.

—_-— formation from milk sugar, 17.

Lactoglobulin, 15.

Lakes, casein colour, 84,

Lanolin, 185.

Lavender oil in casein paint, 80.

Leather, imitation, 125,

Lehmann on rennet, 8,

Lehner’s casein putties, 115.

Leucine, 52.

Liebrecht and Réhmann’s acid casein
compound, 200,

209

Liebrecht and Roéhmann’s neutral
casein compound, 200.

Lilienthal’s plastic mass, 123.

Lime and casein cement, 118.

— colours, casein, 69.

— in casein masses, 109.

— — — paint, 60.

— tempera, 99.

Limeproof pigments, 63.

Limewashes with casein, 75.

Lindet on rennet, 9.

Linen fabrics, casein dressing for, 149.

Linke on binding media, 92,

Linoleum, imitation, 125.

Linseed oil in casein paint, 66.

Liquid casein glue, 110.

— — — Bolder’s, 117.

Lister on bacterium lactis, 17.

Lithium casein compound, 198.

Lithopone in casein paint, 79.

Loading silk, 156.

— textile fibres, 151.

Lysine, 52.

M,

Machines, centrifugal, 18-20.

Magnesia, casein, 155.

Magnesium silicate in casein paint, 79.

— sulphate as a casein precipitant,

48, 51.

Marble, imitation, 142,

— lime paint, 62.

Mares’ milk, casein from, 43,

Marking bags, iron barrels, cases, etc.,
paint for, 84.

Match-making, casein for, 115.

Mayer on rennet, 9.

Medicinal food, patent, 198.

Medium casein for calico printing, 155.

— for casein paint, 92, 97.

Meerschaum, casein bind for, 116.

Mellanby on ‘rennet, 9.

Mending glass, china, etc., 112.

Mercerised crépe, casein for, 153.

Mercury compounds with casein, 198,

Metachromotype paper, 168.

Metallic lustre, printing colour with,
151.

Metals, casein cement for, 117.

— — lime on, 74.

— preparing for painting, 88.

Methods of preparing casein, 30-40.

Meunier and Reithoffer’s patent, 54.

Michaelis and Mendelssohn on milk
clothing, 17.

Mierisch and Eberhardt’s method of
making casein, 33,

14

210 CASEIN.
Mierisch and Eberhardt’s soluble) P.
casein, 195.
Milk, action of acetic acid on, 17. Packing casein, 32,
— — — acids on, 15, — — painis, 63.
— — rennet on, 15. Paint and varnish, Kistory’s, 72.
— — sulphuric acid on, 17, casein, 81.

albumen, Riegel’s, 161.

casein content, 3.

cheese, 16,

curd, 18.

curdling, 4-18.

flour, 160,

food, Ramage’s, 163,

Hall’s synthetic, 163,

paints, 77.

Pokorny on coagulation of, 16,
souring, Pasteur on, 17.

sugar, 16.

synthetic, 163,

_ Mill, cone paint, 67.

Mineral oil, solidifying with casein, 186.
Mixer, Werner and Pfleiderer’s, 62.
Mixers for casein masses, 62.
Mixing casein paints, 61-62,
Molecular weight of casein, 44.
Morin’s insoluble casein, 128.
Mortar, preparation of, 89,

Mother of pearl, imitation, 126.
Mould, preventing, in casein paint, 91.

PAS eae

N.

Nagel on vegetable casein, 29,

Neutral casein compound, 200,

Nitrocellulose and casein compounds,
182, 135.

Non-absorbent surface, 89.

Nutrient milk flour, 160.

Nutrium, 162,

Nutrose, 45.

0.

Oak bark as casein precipitant, 105.
Ochre casein paint, 74.
Oils and fats, paper flasks for, 174.
— in casein paint, 79, 80.
Ointment, casein, 193.
Older method of preparing casein
paint, 65,
Organic acids as casein precipitants,
34, 47, 49.
Origin of casein 3,
Outdoor cement, 90,
Oxalic acid, 52.
Oxidised casein, 199.
Oxyproline, 52.

— analysis of, 66.
application of, 87, 98. .
Brunstein’s, 80,

cement, 85,

enamel, 67.

facade, ‘67.

older method of preparing, 65,
preparing, 87, 93

sundry recipes, 66.

value of, 99.

cold-water in powder, 68.
mill, 67.

quick-drying casein, 79.
remover, 177,

Ring’s cold water, 81.
waterproof, for playing cards, 63.
Paints, casein, 58-86.

— black, 68, 69, 77, 78.

— blue, 68, 73, 74, 77, 78.
— brown, 76, 77.

— brushes for, 95.

— chalk-white, 73.

— for bags, barrels, etc., 84.
— — iron, 73, 84.

— green, 68, 73, 74, 77, 78.
— grey, 77

— lime in, 60.

linseed oil in, 66.
lithopone in, 79.
magnesium silicate in, 79,
marble lime, 62.

Martin on fresco, 90.
medium for, 92, 97.
milk, 77.

mixing, 61-62.

mould preventing in, 91.
ochre, 74.

oils in, 79, 80.

petroleum in, 78.
pigments for, 63, 68, 76, 93.
preparation of, 87, 93.
quick-drying, 79. -

red, 68, 73, 74, 77, 78.
Roman. cement i in, 85.
sodium tungstate in, 149, 152.
storing, 95.

talc in, 79.

thinning, 74.

varnish for, 65, 97.

wall, 73.

waterproof, for cards, 63.
white, 68, 73, 77; 78.

PS bist Ese et eer

Pa el Ret 2d

INDEX.

Paints, casein, woodwork, 73.

— — yellow, 68, 73, 77, 78.

— distemper, 75.

— milk, 77.

— silicate, 75, 78.

— water-colour, 75.

Painting, al secco, 98.

— — sgraffito, 98.

— dry frescoe, 90.

— frescoes on canvas, 96.

— pictures on outside work, 97.

— preparing metals for, 88.

— technics of casein, 87-103.

— tempera, 98.

Paintings, Pompeian wall, imitating,

Pans for preparing casein, 11-13.

Pansiot’s albumen substitute, 163.

Paper, facing for, 170.

flasks, etc., for oils and fats, 174.

industry, uses of casein in, 167.

metachromotype, 168.

sizing with casein, 168.

solution for coating, 170.

washable drawing and writing, 175.

wrappering for food, clothing, etc.,
176.

Paracasein, formation of, 49, 50, 200.

Passburg rotary curd drier, 23.

Pasteur on souring of milk, 17.

Pellicules, photographic, of casein, 179.

Peptone, Dr. Bernstein’s, 197.

— from casein, 197.

Petroleum as a diluent of casein paint,

Phenylalanine, 52.

Phosphate, casein, 197.

— — for baking, 164.

Phosphoric acid, compounds
casein, 197.

Phosphorus, 52.

Photographer’s backgrounds, 185.

Photographic plates, casein, 179.

Photography, uses of casein in, 186.

Pictures on. outside work, painting,
97.

Pigments for casein lime, 71.

— — — galalith, 142.

— — — paints, 63, 68, 93.

Pitch barm cement, 119.

Plasmon, 45, 161.

Plaster for casein painting, 88.

— preparation of, 89,

Plastic mass, Boermann’s patent, 132.

— — from celluloid and casein, 132.

— — of keratin and casein, 127.

— — with a casein basis, 136.

—— masses, casein, 121-146.

with

211

Plastic masses, Kathe’s patent, 131.
— — Lilienthal’s, 123,
— — Soc. anon. franc. de Chim., 128,

‘| — — — — L’Oyonnaxienne, 128.

Plates, casein, 156.

— — in, 107.

— joining casein, 113.

Plinatus’ patent substitute for horn,
ivory, etc., 128.

Pokorny on coagulation of milk, 16.

Polish, shoe, 178.

Porcelain, casein cement, 116, 117.

‘| Portland cement in casein mass, 124.

bac ty in white, 90. ; 7
Potassium bichromate in casein paints,

— compound with casein, 199.
Powder, food, 165.

— glue, 114.

Pozzi and Tondell’s process, 125.
Preparation of casein, 3, 6, 41-57, 189.
— — — paints, 58-86, .

‘|— — metals for painting, 88,

— — mortar, 89.
— — the ground, 87,
Preparing casein adhesives, 104-120.
— surfaces for casein paints, 87, 88.
Prost filter, 27.
Priming for canvas, 186.
Printing colour with metallic lustre,
iets k ns
Proline, 52.
Properties of casein, 3, 6, 41-57, 189.
Punch, whey, 16.
Pure casein, Van Slyke and Hart’s
method, 200.
Purifying curd, 18, 25.
Putties, casein, 104-120.

Q.

Quick-drying casein paint, 79.
Quicklime, 60, 89.

R.

Ramage’s milk food, 163.

Red casein paints, 68, 73, 74, 77, 78.
Remover, paint, 177.

Renken’s method of using glue, 114.
Rennet, action on milk, 8, 15.
Alexander on, 10.

as a casein precipitant, 6-10.
Bang on, 9.

Berzelius on, 8,

casein, 42.

Hammarsten on, 8.

Heintz on, 8,

212

Rennet, Lehmann on, 8.

— Lindet on, 9.

— Mayer on, 9.

— Mellanby on, 9

— Schreiner on, 8.

— Selim on, 8.

— Sdldner on, 8.

— Voelcker on, 8.

Resin in casein masses, 125, 127.
— — — paints, 127.

Revis, Bolton, and -Bacon’s patent
soluble casein compound, 114,
Ricard and Riche’s patent plastic

casein, 39.
Richard’s binding medium, 92.
Riegel’s method of precipitating casein, | —
33

— milk albumen, 161.

Ring’s cold-water paint, 81,

Roéhmann and Hirschstein’s argentum-
casein, 198.

Roman cement in casein paint, 85.

Rooms, drying, 20, 32.

Rosinate, iron, 178.

Rotary curd-drying cylinder, 23, 24.

Ruprecht’s method of preparing casein,
31,

8.
Salicylates, casein compound with,

Salts as casein precipitants, 49, 51.

Sanatogen, 160:

Scheel’s patent for joining casein
plates, 113.

Schreiber on casein, 162,

Schreiner on rennet, 8.

Schryner on precipitation of casein, 10.

Selim on rennet, 8.

Sell’s curd ** Zwieback”’ rolls, 165,

Serine, 52,

Sheeps’ milk, casein from, 43.

Shell, imitation, 145.

Shoe cream, casein, 179.

— polish, Beuse’s, 178.

Sifter and mixer, Gardner’s, 61.

Silicate casein paints, 75, 78.

Silk, loading, 156.

Silver caseate, 189, 190;

— — in photography, 190.

— casein compound, 189, 198.

Sizing material, 156.

— paper with casein, 168,

— textile fibres, 151.

Slaked lime in binding media, 116,

Soap, casein albumose, 195,

Soapmaking, casein in, 193.

CASEIN.

Soc. anon, franc. de Chim. Indt.,
patent plastic mass, 128.

— — L’Oyonnaxienne, patent plastic

masses, 128.

Soda and casein cement, 118.

— caustic, as a casein precipitant, 189,

Sodium arsenate i in casein glue, 34, 105.

—— bicarbonate, 194.

— caseate, 45,

— chloride as @ casein precipitant, 48,

51,

— fluoride as a casein solvent, 52.

— peroxide, 163.

— silicate in casein paints, 75.

— sulphate as a casein precipitant, 48.
— tungstate in casein masses, 107, 152.

Softening textile fibres, 151.

Séldner on rennet, 8,

Solidifying mineral oil, 186.

Soluble casein, 37.

— — compounds, 114.

— — with citrates, 165.

Solution, casein, 113.

Solvents for casein, 91.

Souring of milk, 17, 30.

- Pasteur on, 17.

Spike oil colours, 98.

Spitteler on casein, 31.

Spitteler’s galalith process, 138.

— patent clear, non-milky casein,

138-141.
Stannou’s chloride in casein masses,

Steam generator, 13.

— pan for casein, 12.

Stencil paste, casein, 85.

Stone, casein cement for, 119.

Stopping, casein, 119.

Storing casein paints, 95.

Strontia in casein masses, 123.

Styles, encaustic, 98.

— fresco, 98.

Substitute for boiled oil, 80.

— — celluloid, 133.

— — horn, ivory, etc., 128.

Sugar, milk, 16.

Sulphur, 52.

Sulphuretted hydrogen, 52.

Sulphuric acid as a coagulant of milk,
yt Se

Sulphurous acid, 52.

Sumach as @ casein precipitant, 105.

Sundry recipes for casein paints, 66.

Surface, non-absorbent, 89.

Surgical bandages, casein for, 196.

Synthetic milk, 163.

Szekely’s. patent method of making
casein, 34.

INDEX.

=.

Talc in casein paint, 79.
Tannic acid as a casein precipitant, 105.
Tannin as a casein precipitant, 105.
— in casein cement, 105, 112, 118.
— — — paints, 60.
Tartaric acid, 105.
Technical casein, 37.
Technics of casein painting, 87-103.
Tempera, lime, 99.
— painting with casein, 64, 93.
Textile industry, casein in, 147-157.
Thermoplastic material, 128.
Thinning casein paints, 74.
Threads, casein, 156.
Tin acetate in casein lakes, 84.
— tetrachloride in casein lakes, 84.
Titration of casein, 48.
Treating cement plaster, 88.
— yarns, 151.
Trioxymethylene, 120.
Trojel’s boiled oil substitute, 78.
Tryptophane, 52.
Turpentine, 78.

Tyrosine, 52.

U.

Union Alstiengessellschaft’s cask glaze,
181.

Universal colours, 98.

Urea, 52.

Uses of casein, 1.

Utensils for preparing casein, 10-14,
18-28.

V.

Vacuum driers, Scott’s, 24-26.

Valine, 52.

Value of casein paints, 99.

Van Slyke and Hart’s method of pre-
paring paracasein, 200.

pure casein, 200,

Varnish and paint, Kistory’s recipe

for casein, 72.

— casein, 81.

— glossy, for casein paint, 97.

— water-white casein, 72.

— weatherproof, 98.

Vegetable casein, 29.

Vereinigte Gummiwarenfabrik patent

for making galalith, 54.
Viscose and casein compound, 137.
Voelcker on rennet, 8.

213
W.

Wall covering, casein, 124.
— paints, casein, 73.
Wall-paper, washable, 175.

| Washable cement for deal boards, 118.

— drawing and writing paper, 175.

Wash, calsomine, 79. ;

Washing and draining curd, 20.

Water and fireproof asbestos, paper and
board, 172.

Water-colour paints, 75.

Water-glass, 75.

— and casein cement, 108, 109.

— in casein glue, 108, 109.

Waterproof casein, 196.

— glue, 110.

— paint for cards, 63.

— roofing pulp, 180.

Waterproofing and softening dressing,

153.

— casein masses, 132.

— paper with casein, 169.

— preparation, 171.

— process, Chevalott’s, 155.

Water-white casein varnish, 81.

Weatherproof varnish, 98.

Wendt’s patent casein lithium com-
pound, 198.

Wenk’s casein cement, 118.

Werner and Pfleiderer’s kneading and

mixing trough, 184.

— — — mixer, 62.

Whey, 8, 15, 16.

butter, 16.

champagne, 16.

cheese, 16.

composition of, 16.

punch, 16.

White casein paints, 68, 73, 77, 78.

— Portland cement for frescoes, 90.

Wild cherry bark as casein precipitant,
105.

Wittkowski’s cement, 115.

Wood-cement roofing pulp, 180.

Woodwork, casein-lime for, 72.

— casein paint for, 73.

Wool fat in priming composition, 185.

Wrappering, paper, for food, etc., 176.

De

Yarns, dressing, 151.

Z.

Zanardi on sizing paper, 168.
Zine white, fixing on cotton, 154.
“ Zwieback” rolls, Sell’s curd, 165,

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