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powerful odour and an acid reaction, and acting as a poison. It ex-
plodes violently when heated. Dissolves very sparingly in water and
does not take up water, but when it is left in contact therewith, its surface
acquires a dull- white appearance. Dissolves freely in alcohol. When
this chlorazol, obtained by the treatment of the original proteide, is
distilled alone, an evolution of hyponitric acid takes place, and at about
140 there passes over an oily body (b} resembling chlorazol but differ-
ing in composition and having the sp. gr. 1'628. Lastly, the non-
volatile decomposition-products obtained in the first operation (see below)
yield, by repeated treatment with nitric acid, oily bodies (c and d)
resembling chlorazol.

Analyses by Milhlhauser.





a.


a.


b.


I.


c.


c.


d.


d.


c ..,


18-91 ....


19-44


.... 12-77 ..


, 13-98 ....


12-03 .


... 12-78 ....


13-05 .


... 13-2


H...


, 1-72 ....


2-90


.... 1-19 ..


.. 1-75 ....


1-07 .


... 1-13 ....


0-70 .


... 0-8


Cl...


. 40-19 ....


41-98


.... 56-88




38-40 .


... 38-50 ....


36-80




N ...


. 11-80 ....








13-10 ,


... 15-70 ....


7-80





Calculations, according to Muhlhauser.
b. c.



80 .


19-23


40






13-44


4


C


. 12-70


40


.. 12-6


3H
3C1

2N
8O .


1-20
42-68
11-22
25-65


2H
3 Cl
N
4O


...


*"


1-12
59-66
7-84
17-81


2
2
2

8


H
Cl

N
.


1-06
37-6
14-8
33-8


H
2C1
N
10 O ...


.. 0-52
.. 37-36
.. 7-3

. 42-2



C 8 CPX 2 H 3 100-00 C 4 C1 3 XH 2 lOO'OO C 4 C1 2 X 2 H 2 100-00 C 4 C1 2 XH0 6 lOO'OO

Strecker (Handworterb. 2 Aufl. 2, 2, 166) regards a as a mixture,
and c and d as essentially identical, probably having the composition c.
On this supposition both bodies are homologous with chloropicrin
(xi. 216).

b. The residue in the retort deposits on cooling a large quantity of



GENERALITIES RESPECTING PROTEIDES. 259

a transparent syrupy body, the quantity of which is increased by mix-
ing it with water, then driving" off most of the acid with addition of
alcohol, and again mixing with water. It is purified by boiling with
water.

This second body forms an acid liquid of the consistence of turpentine,
which turns red in the air, smells of bitter almond oil, and tastes
bitter. Sp. gr. 1'36. When heated it becomes thinner, turns brown
and decomposes, without exploding. It is nearly insoluble in water,
but when boiled persistently with water it loses chlorine. When
treated with potash, it gives up part of its nitrogen in the form of
ammonia : acids throw down from the solution a body resembling the
original. It dissolves easily in alcohol and less freely in ether.

Calculation, according to MiiMhduser. Mulilh'amer.

240 .................... 144 ............ 42-29 ............ 40-05 to 43-56

12 H .................... 12 ............ 3-52 ............ 3-30 to 5'33

301 .................... 106-5 ............ 31-28 ............ 29'23 to 34'43

N .................... 14 ............ 4-11 ............ 4-22 to 4-24

80 .................... 64 ............ 18-80

C 24 C1 3 XH 12 4 .... 340-5 ............ 100-00

The second body undergoes further decomposition when it is dis-
tilled with 100 parts of fuming nitric acid. Chlorazol (c) then passes
over, and the residue deposits crystals, while an amorphous body remains
in solution. No oxalic acid is produced. The crystals are white
loose needles, having an odour of benzoic acid and a sour taste ; they
are fusible and susceptible of sublimation, and are represented by the
formula C 14 C1 2 IP0 6 . They dissolve easily in hot nitric acid and are
deposited from the solution unchanged as it cools. The amorphous
body is semi-fluid, ropy, strongly acid, inodorous, very hygroscopic, and
has the composition represented by the formula C 12 C1 2 XIP0 2 . It
volatilises in irritating vapours without leaving a residue; dissolves
slightly in water and easily in aqueous alkalis, with which it forms
crystallisable salts.

c. After the removal of the chlorazol and the second body, there
remain in the mother-liquor, sulphuric, oxalic, and fumaric acids (x, 22),
and a non-volatile third body. Excess of the acids employed is driven
off ; the oxalic acid is allowed to crystallise ; and the thick residue is
mixed with 3 or 4 times its volume of water, whereupon the third body
is precipitated and collects in the form of a heavy oily layer. The
mother-liquor contains salts of fumaric and sulphuric acids.

The third body is a thin oil of brown-red or paler colour, an agree-
able aromatic odour, and acid reaction. It forms an opaque solid in
the cold, and burns without explosion. It dissolves slightly in water,
sparingly in aqueous ammonia, and easily in alkalis. The alcoholic
solution throws down from metallic salts coloured amorphous pre-
cipitates, which lose organic matter on drying. It dissolves freely in
alcohol.



Calculation, according to MilJi
26 156
18 H 18


Miililliauser.
Dried in vacno over
Ihduser. oil of vitriol.
35-57 35-52 35'4
4-11 4-40 4-3
, 24-28 23-42
3-20 3-2
. 32-84


301
N


106-5
14


18 O


144







438-5 ....... 100-00

S 2



260 GENERALITIES RESPECTING PROTEIDES.

When distilled with fuming nitric acid, this third body likewise
undergoes decomposition, by which chlorazol, (d) volatile acids (among
which valerianic acid predominates), crystals, and an oily body are
produced, but no oxalic acid.

The crystals are obtained in small quantity only. They form in-
odorous short white needles, fusible, and volatilisable in irritating
vapours. They dissolve with difficulty in hot water, easily in alcohol,
and are represented by the formula C 16 C1 2 H 6 4 . The potash-salt
contains 20-51 p. c. of potash.

The oil is of a clear pale-yellow colour, nearly inodorous, bitter, and
very acid. It volatilises in white vapours, apparently undecomposed.
The compounds with bases are amorphous, brownish-red or orange.
The oil dissolves sparingly in water, easily in alcohol (Miihlhauser, Ann.
Pharm. 90, 170; 101, 171).

Miihlhauser.
Calculation, according to Miihlhauser. Dried at 100.

240 144 339 33'24 33'11

16 H 16 3'8 4-05 3'9

3 01 106-5 25-0 25-0 24'77

N 14 3-4 3-3 3-3

ISO 144 33-9

C 24 C1 3 XH 16 O 14 .... 424-5 lOO'O

Albumin, fibrin, casein, and wheat-gluten, treated with a mixture
of binoxide of manganese and sulphuric acid, or of bichromate of potash
and sulphuric acid, yield liquid fatty acids, benzoic acid, and the alde-
hydes of these acids ; with bichromate of potash, prussic acid and
valeronitrile are also formed. See further particulars under Casein.

Solid albuminous substances are coloured blue by sulphuric acid
containing molybdic acid (Frohde, Ann. Pharm. 145, 376 ; Chem. Centr.
1868, 640).

All albuminous substances (as, for example, egg and serum albumin,
the substance precipitated by acetic acid from blood-serum, alkaline
solution of fibrin to which enough acetic or phosphoric acid has been
added to redissolve the precipitate first thrown down) are precipitated
from their solutions in acetic acid by neutral salts, such as chloride of
sodium, acetate of soda, phosphate of soda, chloride of calcium, or sul-
phate of magnesia. A similar behaviour is exhibited in solutions con-
taining excess of phosphoric, oxalic, lactic, or tartaric, instead of acetic
acid. The precipitation takes place with especial facility when the
acid solution is heated and cooled again before adding the neutral salt ;
it is effected the more easily the higher the temperature and the
stronger the solution. On dissolving serum-albumin, coagulated by
heat, in very dilute potash-ley, adding acetic acid till the precipitate at
first produced disappears, and then mixing the liquid with an equal
volume of an aqueous solution of sulphate of magnesia, the mixture
remains clear at 13, becomes slightly turbid at 15 to 16, more so
at 19, and throws down dense flocks at 32. 100 parts of a solution of
serum- albumin in phosphoric acid, when mixed with 1 part of a solution
of chloride of sodium, do not become turbid even on boiling ; 6 parts of
the salt solution cause turbidity at 50, 8 parts at 27, and 10 parts at
19. Acetic and phosphoric acid solutions of egg- and serum-albumin
and of fibrin, behave in the same manner ; coagulated egg-albumin
dissolved in acids is precipitated only at higher temperatures, or by a
larger proportion of neutral salts, than serum-albumin.



GENERALITIES RESPECTING PROTEIDES. 261

The precipitates thus formed, Panum's acidalbumin, exhibit the fol-
lowing reactions. After the removal of salts, they dissolve in water,
especially in very cold water, forming solutions which are not coagu-
lated by heat ; they lose this property, however, when dried in the air,
or when heated with saline solutions. Before they are altered by
exposure to air, they dissolve in excess of acetic or phosphoric acid,
and sometimes in cold or warm alcohol. Their aqueous solutions are
precipitated by ferrocyanide of potassium, an excess of which redis-
solves the precipitate, whereas solutions of albumin are precipitated by
ferrocyanide of potassium only after addition of acetic acid, and the
resulting precipitate is insoluble in excess of the precipitant (Panurn,
N. Ann. Chim. Phys. 37, 237 ; J. pr. Chem. 59, 55).

When white of egg is diluted with an equal volume of water and
filtered, and the filtrate is saturated with neutral salts, solutions are
obtained (albumino-saliue solutions) which behave as follows :

They are precipitated by tribasic phosphoric acid, except when the
salt added is borax, phosphate of soda, acetate of potash, or acetate of
soda. The precipitates are granular, and soluble in excess of phos-
phoric acid. They give with acetic acid, granular or flocculent precipi-
tates, which are insoluble in excess of acetic acid, and dissolve in
phosphoric acid only when they are granular; this last solution is again
precipitated by excess of acetic acid. The precipitates produced by
acetic acid are insoluble in ammonia, either cold or warm, and in cold
strong potash solution (Melsens). For the behaviour with corrosive sublimate
see egg-alburnin.

When the solutions used in these reactions are so dilute that no
precipitates are produced, fibres make their appearance in them on
stirring-, which fibres afterwards unite to form membranes (Melsens).
On the behaviour of albumin with very dilute hydrochloric acid and chloride of
sodium, see Arnold (Schmidt's Jahrb. 103, 1).

According to Eichwald (Chem. Centr. 1869, 565) these precipitates
consist of mixtures of paraglobin and syntoniu in varying proportions,
according to the kind and quantity of the acid contained in them.
When to a mixture of equal volumes of serum and saturated solution
of chloride of sodium, so much hydrochloric acid is added that 100 c.c.
of the mixture contain from 0'5 to 1-0 gramme of hydrochloric acid, and
the mixture is filtered after standing for a day or longer, the resulting
precipitate forms with water a strongly acid solution, from which soda,
or carbonate of soda, added till the reaction is very feebly acid, gradu-
ally throws down syntonin, whilst coagulable paraglobin remains in
solution. If, on the contrary, the precipitate be freed from adhering
acid, by washing it with a half-saturated solution of chloride of sodium,
water then dissolves the paraglobin (owing to the presence of chloride
of sodium) and leaves the syntonin undissolved. The only peculiarities
exhibited by the paraglobin contained in the precipitate are, that it does
not lose its coagulability, and is not converted into syntonin, even on
standing for months in a solution containing much hydrochloric acid, as
would be the case with paraglobin alone in contact with hydrochloric
acid. When acetic acid is used to precipitate the mixture of serum
and chloride of sodium, the precipitate is perfectly soluble in water,
even after washing with chloride of sodium (Eichwald).

When serum, previously freed from paraglobin and diluted with ten
times its bulk of water, is mixed with so much acetic acid that it no
longer coagulates on boiling, but is completely precipitable by ferro-



262 GENERALITIES RESPECTING PROTEIDES.

cyanide of potassium, and then with its own volume of a saturated
solution of chloride of sodium, syntonin is thrown down as a greyish-
wliite precipitate, which slowly contracts to a dense mass. When this
precipitate is freed from excess of acid by washing 1 with a half -saturated
solution of chloride of sodium, water first takes up part of the chloride
of sodium, and then dissolves the precipitate itself. The solution has a
faint acid reaction, coagulates partially on boiling, and completely after
addition of a small quantity of carbonate of potash, whilst excess of
alkali prevents coagulation. The solution is precipitated by strong
mineral acids ; the precipitate produced by nitric acid is nearly insoluble
in excess of the precipitant, but that produced by sulphuric acid is com-
pletely soluble. The solution is precipitated also by neutral acetate of
lead, corrosive sublimate, tannic acid, and cupric sulphate, the pre-
cipitate produced by the last being soluble in excess (Eichwald).

Strong potash-ley produces with albuminous substances the bodies
hereafter described as albuminates (Mulder's protein). These bodies
resemble one another in their behaviour towards reagents, but exhibit
some differences amongst themselves in their action on polarised
light.

Albumin, casein, and fibrin, treated with fused hydrate of potash,
yield volatile ammoniacal products, leucine, tyrosine, volatile acids, and
non-crystallisable substances.

Solutions of proteides (albumin, fibrin, casein, glutin, legumin) in
potash yield iodoform when treated with iodine and bicarbonate of potash
(Millon, Compt. rend. 21, 828 ; J. pr. Chem. 37, 53).

Liquids containing albumin, fibrin, casein, or gelatin assume, on
addition of potassio-cupric tartrate, a fine violet colour like that of per-
manganate of potash. This colour is produced with very small
quantities of the albuminous substances, at least on heating. Acids
decolorise the solution, whereas alkalis restore the colour (Humbert,
N. J. Pharm. 27, 272 ; Kopp's Jahresber. 1855, 825). Solid albuminous
substances and their derivatives assume a deep violet-blue colour when
moistened with cupric sulphate and then with potash (Piotrowski,
Wien. Acad. Ber. 24, 335 ; Kopps Jahresber. 1857, 534). The skin of
the finger, feathers, silk, gelatigenous substances, yeast, and sponge,
likewise exhibit the violet coloration when moistened with cupric
nitrate and soda-ley (A. Vogel & Reischauer, N. Repert. 8, 529 ; Kopp's
Jahresber. 1860, 566). Ritthausen (J. pr. Chem. 85, 208 ; 99, 449 ;
102, 376) adds to the acetic solution of the albuminous substance a
little cupric sulphate, and then potash-solution, whereupon, if albumin,
casein, or legumin is employed, the violet colour appears. On dropping
the cupric sulphate into the alkaline solution and shaking, the precipi-
tate formed at first is redissolved with violet colour. In presence of
dextrin or sugar, the solution is coloured blue, without any precipitate
of cuprous oxide being formed. See also under Egg-albumin.

Protein substances (albumin, fibrin, casein, silk, wool, gelatin, horn)
added to a solution of 1 part of mercury in 1 part of nitric acid and 41
parts of water, produce an intense red coloration, which is increased by
warming. This is the case not only with the undissolved substances,
but also with their aqueous solutions, and more especially with solu-
tions in alkalis or sulphuric acid. Neither mercurous nitrate nor mer-
curic nitrate produces this coloration, except in presence of nitrous acid
(Millon, Compt. rend. 28, 40; Ann. Pharm. 72, 349). A solution of
mercuric oxide in nitric acid, not in excess, colours albuminous sub-



OXYPROTEIN. 263

stances orange (not red) on boiling, but after addition of a few drops
of highly diluted fuming nitric acid, the colour produced is a dark
purplish-red. The white precipitate produced on boiling albumin with
the mercuric solution likewise turns red on warming it, after washing
and drying, with a trace of impure nitric acid (Kiihne & Rudneff,
Virchoiv's Arch. 33, 71 ; Anal. Zeitschr. 4, 449). See also Lassaigne &
Labaillef {Ann. Chim. Pliys. 45, 435) who consider the presence of both
inercurous and mercuric salt to be necessary.

In contact with oil of vitriol and sugar, the protein substances albu-
min, casein, and globulin, and likewise the vegetable proteides, exhibit
a red coloration ; the gelatigenous tissues, under the same circum-
stances, acquire a dirty yellowish-red colour; chondrin, glutin, and
elastic fibre remain uncoloured. When the white of hens' eggs is
diluted with 5 parts of water, and oil of vitriol is gradually added to
the filtrate till the precipitate produced at first is redissolved, the further
addition of a few drops of a solution of cane-sugar produces a red to
deep- violet coloration, which becomes most intense in a quarter of an
hour. Ammonia (not in excess) throws down from the solution violet
flocks which, after washing, dissolve in oil of vitriol with purplish-red,
and in dilute sulphuric acid with violet- red colour. These flocks are
coloured violet by hydrochloric acid, and yellow by nitric acid ; they
dissolve in potash and ammonia (M. S. Schultze, Ann. Pharm. 71, 266).
See also xv, 322 and xviii. Koschlakoff & Bogomoloff (Anal. Zeitschr. 7,
514) distinguish these reactions from the similar reactions of the bile-
acids by means of the spectroscope.

Gastric juice, either artificial or natural, dissolves most proteides at
30 to 45, forming syntonin and laevorotatory peptones, which are not
thrown down by boiling with water. On the putrefaction of proteides, see
more particularly Casein.

On the behaviour of proteides with diastase, see Mulder (Scheik. Verhandel. en
OnderzoeJc. 2 Deel, 2 Stuk, OnderzoeJc. 130 ; Kopp's Jahresber. 1858, 536) : on their
behaviour with pigments, see Maschke (J. pr. Chem. 76, 37).

2. Mulder's Derivatives of Protein Substances.

a. Protein-oxide or Oxyprotein. Formed when chlorite of protein
is dissolved in aqueous ammonia.

This solution, the formation of which is attended with the evolution
of a large quantity of nitrogen, leaves on evaporation a residue soluble
in hot water, from which boiling alcohol precipitates oxyprotein, whilst
chloride of ammonium remains in solution.

Oxijprotein is a yellow powder which cannot be obtained free from
chlorine, even by repeated boiling with alcohol. It is soluble in water,
and the solution gives with sulphuric acid a white precipitate, which
disappears on heating. It dissolves in strong hydrochloric acid, form-
ing a solution which turns brown when heated. Nitric acid
converts it into xanthoproteic acid. It is dissolved by ammonia,
alkalis, and baryta-water. The aqueous solution is not affected by
ferrocyanide of potassium, but is precipitated by infusion of galls, and
by salts of silver, lead, iron (ferric salt), and copper ; the precipitate
formed by acetate of copper contains 3'64 p.c. CuO. Oxyprotein is
insoluble in alcohol and ether. It contains, on the average (as prepared
from albumin or casein), 50-18 p. c. C., (5-67 II., 15-12 N., and 0'5 Cl.
(Mulder, J. pr. Chem. 20. 340).



264 DERIVATIVES OF PROTEIDES.

Van Laer (ScheiJeund. Onderzoek. 2, Stuk. 75 ; Berzel. Jahresber. 23,
617), who prepared oxyprotein with proteinchlorous acid from hair,
found 51-62 p. c. C., 6-67 H., and 15'07 N. On his bioxyprotein from
hair, see Horn-substance.

Subsequently (Berzel. Jahresber. 23, 595) Mulder regarded this de-
composition-product of proteinchlorous acid as identical with sub-
stances w T hich he found in the animal body, and also prepared from
albumin and fibrin, and then described it as trioxy protein, hydrate of
trioxyprotein, or bioxyprotein.

The oxyproteins occur in the blood, especially in that of the arteries,
and in Crusta inftammatoria. They are produced from fibrin by assimi-
lation of oxygen, which takes place either at ordinary temperatures or
on boiling with water, with access of air. Yeast contains a body
which may be converted into proteinchlorous acid and trioxyprotein.
Pyin is trioxyprotein (Berzel '. Jahresber. 24, 711) : boiled flesh contains
a mixture of bioxyprotein and fibrin.

When fibrin is submitted to prolonged boiling with water in contact
with the air, the portion remaining undissolved consists of bioxyprotein ;
on evaporating the solution to dryness and treating the residue with
alcohol, trioxyprotein remains behind. Trioxyprotein is C^N*!! 2 ^ 13 or
C 40 X 5 H 32 16 ; its copper-compound is C 40 N 6 H 31 Cu0 16 + C 40 X 5 H 32 18 . Ac-
cording to Schroder (Scheik. Onderz. 3, Stuk. 259 ; Berzel. Jahresber. 23,
598), the lead- and silver-compounds have a corresponding composition.
When trioxyprotein is dissolved in potash and precipitated by a
current of chlorine, the precipitate consists of trioxyproteinchlorous
acid, from which ammonia again produces trioxyprotein (Mulder, Berzel.
Jahresber. 23, 595. Scheik. Onderz. 1, 550; Ann. Pharm. 47, 300;
Berzel. Jahresber. 24, 654. J. pr. Chem. 44, 501).

Hoppe-Seyler (Virchow's Arch. 5, 171), by boiling dried serum-
albumin with water, under a pressure of 3 atmospheres, oblained a
turbid liquid behaving like Mulder's trioxyprotein. The epidermis of
Trepidonotus natrix, freed from connective tissue, yields by the same
treatment protein-oxide or a similar body. These bodies are therefore
formed without assimilation of oxygen (Hoppe-Seyler).

j8. Xanthoproteic acid. Previously noticed by Fourcroy & Vau-
quelin and by Berzelius (p. 258). Produced by the action of nitric
acid on protein-compounds.

Mulder digests in nitric acid for 24 hours, protein previously soaked
in water ; dilutes ; filters ; washes the resulting lemon-yellow powder
till it becomes dark-yellow, whereby excess of nitric acid is got rid of ;
then dries, and frees the product from fat by boiling with alcohol and
water.

Xanthoproteic acid thus prepared is an orange-yellow powder con-
taining, on the average, 50-37 p.c. C., 6-60 H., 14-00 N., and 27-99 0.
It dissolves slowly to a red jelly in oil of vitriol ; and from this jelly
water throws down a compound of Xanthoproteic acid with sulphuric
acid, from which water removes the whole of that acid. The
solution in nitric acid is rendered colourless by boiling, with formation
of oxalic acid. The yellow solution in hydrochloric acid leaves on
evaporation a brown deliquescent mass. Xanthoproteic acid evolves
ammonia when boiled with excess of potash. It dissolves in ammonia,
forming a solution which, when evaporated, leaves the acid free from
ammonia. Chlorine passed into the red ainrnoniacal solution decolorises



PROTEINCHLOROUS ACID. 265

it and throws down yellowish-white flocks, which are lemon-yellow
after drying; according to Mulder, they contain chlorous acid, and
yield xanthoproteic acid when again treated with ammonia. The acid
is insoluble in water, alcohol, and ether. It dissolves in nitric acid, and
is precipitated from the solution by water. It forms a dark-red neutral
salt with potash ; neutral and acid salts of the heavy metals ; and an
insoluble lime-salt (Mulder, Berzel. Jahresber. 19, 561. J.pr.Chem.
20, 352).

Van der Pant (Scheikund. Onderzoek. 5, 2 Stuk. 136 ; Kopp's Jahresber.
1849, 507) obtained xanthoproteic acid of nearly the same composition
from albumin, cow-horn, horse-hoofs, blood-fibrin, cheese, wool, horse-
hair, and protein from albumin or horn, by submitting these bodies to
more or less prolonged digestion with nitric acid, washing the undis-
solved residue, treating it with ether, and drying at 130. It forms an
ammonia- salt which is decomposed at 130, leaving unchanged xantho-
proteic acid ; a soluble baryta-salt containing 12-7 to 13'1 p. c. BaO ; a
green, insoluble copper-salt containing 12'9 p. c. CuO ; and a yellow,
insoluble lead-salt containing 14/0 p. c. PbO.

XantJioproteic acid, according to van der Pant.



a'
C


From
Lbumin.
50-3 ....
6-4 ....
14-8 ....
27-3 ....
1-1 ....
O'l ....


From
horn.
50-1
6-2
14-8 .
27'2 ,
1-7
O'l .


From
horse
hoofs.
.... 49-5 ..
6-5


From
fibrin.
.. 49-3 ..
6*2


From
cheese.
.. 50-7 ..
6'3


From
wool.
... 49-4
6'4


From
hair.
.... 49-2 ....
6'0


From protein.
50-9 .... 50-6
6-6 .... 6-4
14-8 .... 14-7
26-21
1-5 / " 282


H


N
O

s

Ash....


... 14-1 ..
,... 28-4 ..
... 1-3 ..
... 0-2 ..


.. 14-8 ..



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