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1860, 772; Kopp's Jahresb. 1860, 597. Compt. rend. 56, 1128;

Chem. Centr. 1863, 964 ; Kopp's Jahresb. 1863, 657.
LUCRE. Arch. f. klin. Chirurgie 3, 135 ; Chem. Centr. 1863, 966 ;

Jahresb. 1863, 658.

Formed occasionally in pus from wounds, which then colours the
bandages blue. According to Lticke, its formation is connected with
the presence of vibrios. See also Chalvet (-#. J. Pharm. 38, 377).
The occurrence of a blue substance in pus had already been observed by Braconnot
(J. Chim. med. [3], 18, 454), Overbeck (N. Er. Arch. 81, 159), and Delore (Compt.


rend. 51, 296), this substance being designated by Overbeck as pi/overdin, by Delore
as cyopyin. In other cases the blue colour of pus is produced by ferrous phos-
phate (S. Schiff, Ann. Pharm. 106, 108 ; Jahresb. 1859, 192 ; Schlossberger, N.
Jahrb. Pharm. 10, 81).. On the pyin of Guterbock (see Handbuch viii, 526 ; Leh-
mann's Physiological Chemistry iii, 156). This substance is, according to Eichwald
(Wiirzburg med. Zeitschrift. 5, 298), a mixture of peptone with unaltered or modified

Preparation. The baudages are steeped in water ; the pyocyanin
and pyoxanthose are dissolved out of the extract by agitation with
chloroform ; and the pyocyanin is transferred to water by agitation with
weak aqueous hydrochloric acid, the pyoxanthose then remaining
digested in the chloroform. By mixing the aqueous solution with
carbonate of baryta, filtering, agitating the filtrate with chloroform,
and leaving the chloroform solution to evaporate, the pyocyanin is
obtained in the separate state, and may be freed from adhering pyox-
anthose by washing with ether (Fordos). Lucke proceeds in a similar

Properties. Blue prisms or needles grouped in crosses or rosettes ;
according to Lucke, sometimes also blue or green laminae. Melts
when heated, and does not sublime.

The crystals of pyocyanin, as well as its solution in chloroform,
become greenish-yellow on keeping, from formation of pyoxanthose.
On washing the crystals with ether, the pyoxanthose dissolves, and the
blue colour is restored (Fordos). Impure solutions become decolorised
when left in closed vessels or heated with sulphide of sodium, and
turn blue again (though not always, according to Lucke) on exposure
to the air. The aqueous solution is decolorised by chlorine, transiently
also by carbonic acid, permanently by oil of turpentine (Lucke).

Pyocyanin is soluble in water. It unites with acids, which redden
the aqueous solution ; with hydrochloric acid it forms red four-sided
prisms ; with acetic acid, a red solution which loses acid on evaporation
(Fordos). Strong acids decompose it when heated (Lucke). Alkalis
turn the acid solution blue again (Fordos). The alcoholic or aqueous-
a^aline solution is not precipitated by alum or by neutral acetate of
lead (Lucke).

Pyocyanin dissolves in alcohol and in chloroform, less easily in ether.

Pyoxanthose. This yellow colouring matter of blue pus is obtained
by evaporating the above solution in chloroform after addition of water,
filtering the aqueous solution, extracting with chloroform, and evapo-
rating. It then sometimes, though rarely, remains crystallised, forming
confused groups of microscopic needles, slightly soluble in water, easily
in alcohol, ether, chloroform, bisulphide of carbon, and benzene. It is
reddened by acids, coloured violet by ammonia or potash (Fordos).

Chlororhodic acid. An acid sometimes occurring, according to
Boedecker, in pus. Dried and pulverised pus is freed from fat by ether
and boiled with alcohol of 75 p. c. ; the liquid is filtered and evaporated,
and the residue is boiled with water. The unfiltrable solution is freed
by acetate of lead from substances precipitable by that reagent, then
from excess of lead by sulphuretted hydrogen and evaporated. The
chlororhodic acid is extracted from the residue by absolute alcohol,
together with a little common salt, and remains on evaporation as a
soft, yellowish mass. Loose chalk- white powder made up of small
needles ; melts when heated, and burns with an animal odour.


The dry acid does not dissolve in boiling water till after addition of
alkalis ; this solution is not precipitated by acids, not after ncutralisa-
IOM, by metallic salts, excepting stannous chloride, mercuric chloride

and mercuno nitrate, which throw down white flocks. Tincture of
galls likewise throws down white flocks, tincture of iodine yellow flocks
chlorine-water colours the liquid a fine rose-red, the colour beinff
destroyed, however, by excess of the reagent. The acid dissolves
easily in alcohol, but is insoluble in ether (Boedecker, Zeitschr. f. ration
Medicin: rene Folge, 6, 198).

On the Chemical Composition of Pus, see Miescher, Med-chem. Unters

1 i 4 3 ; 9?' C - J ' [2] 9 - Hoppe-Seyler, Med-chem. Unters.
, 486 ; Chem. Soc. J. [2] 9 ; also ADDENDA to this volume.


L. GMELIN. Sclav. 10, 507 ; Handb. 3, Aufl. 2, 1170.
SCIIERER. Ann. Pharm. 40, 63.

L. Gmelin's Black Pigment of the Eye (Augenschwarz). Occurs as
a thick coating on the choro'id of the eye.

The carefully prepared choroi'ds of ox-eyes are cleansed from blood
by immersion in water ; the melanin is separated from the choro'id with
a camel-hair brush, then left to deposit, stirred up with water, and
filtered through linen to remove residues of membranes ; the liquid
which runs through is evaporated ; and the residue is boiled.

Brown-black lumps, dull, easily pulverised, sinking in water,
infusible (Gmelin). After deduction of 9-8 p. c. ash, it contains, on
the average, 56-88 p. c. C., 5-95 H., 13-76 N., and 23-41 0. (Scherer).
In the black pigment of goats' eyes, Schwarzenbach (Pharm. Viertelj.
11, 37) found 92*06 p. c. ferruginous inorganic constituents to 7-94 p. c.

By dry distillation it yields, without tumefaction, empyreumatic
products and carbonate of ammonia ; the ash contains common salt,
phosphate of lime, and ferric oxide. Smoulders when set on fire.
Chlorine-water renders the colour of melanin paler, and half dissolves
it ; the undissolved portion is turned brown by aqueous potash ; dis-
solves, and is precipitated in brown flocks by acids. Fuming nitric
acid dissolves it, with effervescence, to a red-brown, not bitter liquid,
from which potash-ley and water throw down yellow-brown flocks.
Oil of vitriol dissolves it at a gentle heat, with evolution of sulphurous
acid, forming a black liquid precipitable by water. In hot aqueous
potash ley it dissolves slowly and imperfectly, with evolution of ammonia,
forming a red-brown liquid, from which hydrochloric acid throws down
brown flocks soluble in cold potash. Ammonia acts less strongly than
potash (Gmelin).

Insoluble in water, dilute acids, lime-water, alcohol, ether, and oils, both
fixed and volatile (Gmelin).

A black pigment deposited in a diseased lung was found by
C. Schmidt. (Lehmann's Lehrbuch. d. physio?. Chemie, 1, 296) to contain in
two cases : a. 72-95 p. c, carbon, 3'89 nitrogen, 4-75 hydrogen, and
18-41 oxygen. b. 66'76 carbon, 8-29 nitrogen, 7'33 hydrogen, and



17*61 oxygen. In other cases the black lung-pigment has been found
to consist of carbon, or even of sulphide of iron (Perls, J. pr. Chem.
105, 81).

The black colouring matter found in the liver of patients suffering
from melanotic cancer, consists of uromelanin (p. 411) (Thudichum).
When the black nodules separated from the liver are left under water
for a year, the putrefaction which ensues destroys the foreign sub-
stances, but not the uromelanin. (The further treatment as described in the
Chem. Centr., is unintelligible, Kr.). Hard, amorphous, dark brown powder,
withoat taste or smell. When heated it smoulders slowly, and without
fusion, and burns away with an odour of horn. Dissolves easily
in fuming nitric acid, forming a deep red liquid. Strong hydro-
chloric acid acts in a similar manner, whereas oil of vitriol scarcely
acts upon it. Chlorine decolorises the melanin quickly in alkaline
solution, slowly when suspended in acids. By fusion with potash,
volatile fatty acids are produced.

Melanin swells up in water like albumin, and colours warm water
brown. Dissolves in the aqueous hydrates, monocarbonates, and
bicarbonates of the alkalis, also in aqueous urea, with evolution of am-
monia if heat is applied. The alkaline solutions are precipitated by
acids and salts ; the solution in potash-ley becomes decolorised after
standing for a year, and then yields a white precipitate with acids.
Dissolves in boiling alcohol, with brown colour, not in alcohol containing
sulphuric acid ; insoluble also in chloroform and bisulphide of carbon.

After deduction of 1-47 p. c. ash, it contains on the average
51'73 p. c. carbon, 5-07 hydrogen, 13*24 nitrogen, and 29'96 oxygen,
agreeing with the formula C 18 N 2 H 10 8 (Dressier, Prager VierteJjahrsschr.
f.prakt. HeiKunde, 88, 9 ; Chem. Centr 1866,*395).

According to Pribram (Prag. Vierteljahrsschr. loc. cit. ; Chem. Centr.
1866, 397) a black pigment from the urine of a patient suffering from
melanotic cancer of the eye, belongs to this place.

Sepia Black. Examined by L. Gmelin (Schw. 10, 533) ; by Prout
(Thorns. Ann. 5, 419) after exhaustion with water and hydrochloric

Prout found sepia-ink to be infusible and difficult to burn ; the ash
contained a large quantity of ferric oxide. It was insoluble in warm
hydrochloric and sulphuric acid ; dissolved in nitric acid with red brown
colour and evolution of nitrous gas ; partly in warm aqueous ammonia,
and in boiling potash-ley, forming a dark brown solution, from which
it was partially precipitated by hydrochloric or sulphuric acid, not by
nitric acid. Gmelin found a small quantity of iron in the ash; the ink
dissolved in oil of vitriol, and was precipitated by water.

Bizio (Schiv. 45, 128) described as Mela'in the black of sepia, appa-
rently altered by nitric acid, which he obtained by diluting sepia-ink
with water, boiling the portion which remained on the filter with water
and alcohol, then with dilute nitric acid (whereupon carbonic acid and
nitric oxide were evolved), and washing out the adhering acid with
aqueous carbonate of potash and with water. It is a soft black powder,
which detonates when heated ; is not decolorised by chlorine ; is decom-
posed by strong nitric acid ; and when heated with oil of vitriol, is con-
verted, with evolution of sulphurous acid, into a pulpy mass, from
which water separates unaltered melain. It dissolves completely in
boiling water, forming a black solution, from which it is precipitated by


mineral acids, metallic salts, and alcohol, scarcely at all in hot hydro-
chloric acid, in aqueous alkalis, even in the cold, and is completely pre-
cipitated from the black viscid solution by acids. Acetic acid, alcohol
and ether do not dissolve melain.

The dried contents of the ink-bag of the cuttle-fish is, according to
Ilosams, very hard and black ; has a conchoidal fracture ; sp. gr.
1*275 ; appears amorphous, even under the microscope; and contains,
to 21 p. c. water, 11-02 p. c. ash, free from iron and phosphorus. The
organic substance, after deduction of ash, contains 42-2 p. c. C., 9-9 N.,
3-3 II., and 42-6 0. The black is charred by oil of vitriol, and
dissolved by nitric acid, mostly with red colour; hydrochloric acid
dissolves the inorganic, and attacks the organic substance. Strong
potash-ley dissolves the black, with fishy odour, forming a brown
liquid ; water, acetic acid, alcohol, chloroform, ether, and benzol do not
dissolve it. A fossil sepia from the Lias slate contained 36-8 p. c.
ash ; the black, less easily attacked colouring matter contained 63-8 p. c. C.,
3-4 N., 7-2 II., and 25-6 0. (Hosseus, N. Br. Arch. 120, 27 ; Chem. Centr.
1865, 164 ; Kopp's Jahresb. 1864, 675). A sepia examined by Schwar-
zenbach (Pharm. Viertelj. 11, 37; Kopp's Jahresb. 1862, 539) contained
to 80-63 p. c. colouring matter, 4-6 mucus, and 14-77 ash, likewise free
from iron. It gave off ammonia without melting* when heated ; did
not dissolve in aqueous ammonia, and was slowly decolorised by chloride
of lime.

Colouring Matter in the Mantle of the Black Dew Snail. The snails
freed from their entrails are digested with moderately dilute nitric acid,
till they assume a dirty flesh-colour ; the violet solution is filtered ; and
the filtrate is treated with ammonia, which throws down a dark brown
precipitate. Black brittle mass, having the appearance of Indian ink,
and still containing a large quantity of phosphate of lime. Insoluble
in water. Dissolves in mineral acids, imparting to them a splendid
violet to black colour. The solution in nitric acid becomes crimson
after long standing, and is finally decolorised. Insoluble in alcohol,
very slightly soluble in glacial acetic acid, insoluble in oils either
fixed or volatile (A. Vogel, jun., & Reischauer, N. Repert. 6, 355 ; N.
Jahrb. Pharm. 9, 179 ; Kopp's Jahresb. 1858, 576).

Colouring Matters of Birds' Feathers. The colours of birds'
feathers are not always due to isolable pigments, but sometimes to
optical phenomena. From those feathers which exhibit the same
colour by reflected and transmitted light, colouring matters may be
extracted, and among these the yellow, red, lilac, and green (zoofidvin,
zooerythrin, zooverdin), are soluble in ether and alcohol, whereas the
black zoomelanin is insoluble in these liquids, but soluble in ammonia
and in potash. The latter is .probably identical with the melanin of the

The red of the feathers of Cahirus auriceps may be extracted with
boiling alcohol, and remains, on evaporating the tincture at 60 70, as
a dark, orange-coloured powder, which is altered by light, and dissolves
in boiling water. From the light violet feathers of Catinga ccerulea,
boiling alcohol and acetic acid extract the colour ; the latter solution
becomes colourless on standing.

The beautiful blue-violet wing-feathers of iheTouracos lose their colour
when the bird gets wet, and then give a red stain. On drying, they
recover their original colour, or acquire a blue colour if the bird has

2 E 2


died in the interval. In the dead bird the colouring matter has become
insoluble in water. When the feathers are soaked in ammonia-water,
and the filtrate is precipitated with acetic acid, the pigment is obtained
as a red powder (Bogdanow).

The pigment is Church's turacin. The beard of the feather is washed
with alcohol and ether, and the colouring matter is extracted with
water containing T i^ of alkali, and precipitated with hydrochloric
acid. Amorphous laminae of deep violet-purple colour, crimson by
transmitted light. Not altered at 100, but above that temperature it
becomes bluish dark green, begins to melt, and gives out violet fumes.
Contains nitrogen and 5-75 to 5'89 p. c. copper, which cannot be
removed by dilute acids. The solution exhibits a spectrum with two
black absorption bands. Dissolves with decomposition in fuming- nitric
acid, forming a deep brown liquid, and is decomposed by oil of vitriol.
Dissolves in pure water, with rose-red colour, not in acid or saline
water. Dissolves with blue colour in alkaline liquids ; with concen-
trated alkalis decomposition takes place, and an odour of volatile bases
is emitted. Insoluble in alcohol and in ether (Church, Chem. News, 19,
265; Zeitschr.f. Chem. [2], 5, 445).

Yellow -green feathers give up their colouring matter to hot acetic
acid ; after evaporation of the acid, the pigment dissolves in alcohol.
The yellow pigment of the feathers of Oriolus galbula likewise dissolves
in acetic acid, but the solution quickly loses its colour (Bogdanow,
Compt. rend. 45, 688 ; 46, 780 ; 54, 660) ; the last paper also contain
observations by Schlegel and J. Yerreaux.

Colouring Matter of Crabs and Lobsters. Occurs, according to
Macaire, in two membranes situated beneath the calcareous shell ; in
the external green membrane and the calcareous shell itself it is found
in the brownish -green state, from which it passes into red by heating
to 62 75 in the air or in oxygen gas (not in hydrogen or carbonic
acid), or by putrefaction, or by the action of acids, alkalis, or salts ; in the
inner reddish membrane it exists already in the reddened state. In
crabs having very soft membranous shells, a blue pigment is deposited
below, and a brownish -green pigment above the membrane which
extends between the shell and the flesh (Witting).

The blue colouring matter of the river crab is nearly insoluble in
water, but dissolves in alcohol with bluish colour, changing to red; it is
coloured a fine crimson-red by ammonia, brick-red by acetic acid, and
is apparently but little altered by chlorine. The pigment reddened by
ammonia is not altered by hydrochloric acid. Carbonate of soda pro-
duces but little alteration in the pigment reddened by boiling water ;
it colours the unaltered pigment a fine purple-red, which colour dis-
appears almost wholly on addition of hydrochloric acid, completely on
addition of nitric acid. Crab shells also quickly become red on expo-
sure to the air (Witting, J. pr. Chem. 73, 121 ; Kopp's Jahresber. 1858,

By boiling crab skins with alcohol and evaporating, a fatty red
fusible mass is obtained, which when heated, burns with evolution of
ammonia and leaves a ferruginous ash. The red substance is decom-
posed by chlorine, nitric acid, or oil of vitriol, turned green in alcoholic
solution by acids, and not restored by alkalis (Macaire). According to
Lassaigne. it dissolves easily, with red colour, in dilute sulphuric acid,
and according to Macaire, with the same colour in warm aqueous


potash, whence it is precipitated by acids without alteration. The
alcoholic solution is slowly decolorised by alum, and precipitated red on
addition of ammonia. Neutral acetate of lead j >n>< luces a copious
violet precipitate. Crab-red dissolves with reddish-yellow colour in
alcohol and ether, also in warm volatile oils, but not in fixed oils
(Macaire, Bibl. univ. 1821 ; abstr. Schw. 33, 257 ; Lassaigue, J. Pharm.
6, 174).

The eggs of crabs and lobsters contain a colouring matter dis-
solved iu albumin, identical with that which gives rise to the reddening
of the shells on boiling. Lobster eggs yield when crushed a green
albuminous liquid, which deposits the colouring matter on dilution
with water. This colouring matter is green, resinous, and uncrystal-
lisable, turns red when dried, even at ordinary temperatures, also in
contact with dehydrating salts, alcohol, ether, and acids, and even when
merely rubbed with a solid body. When the albuminous liquid of the
eggs is heated, the albumin, as it coagulates, takes up the colouring
matter, and is coloured red thereby. From this precipitate it is
extracted by alcohol (Valenciennes & Fremy, N. Ann. Chim. 50, 165 ;
Jahresb. 1854, 687).

According to Grote (Compt. rend. 1814, 44), when pulverised and
boiled crab shells are heated with potash-ley till the liquid becomes
orange-yellow, and the nitrate is mixed with hydrochloric acid and
again heated, crab-red separates after a while in dark red flocks soluble
in alcohol.

According to Gobel (Schw. 39, 426), the red pigment of the red
feet and beaks of birds is identical with crab-red. On removing the
epidermis from pigeons' feet after maceration in water, the pigment
comes to light, and may be scraped off. After being dissolved in
alcohol or ether, and recovered by evaporation, it appears red, of the
consistence of tallow, melts in hot water to red oily drops which
solidify on cooling, and makes permanent grease-spots on paper. It is
decomposed by nitric and by sulphuric acid, is insoluble in water and
acetic acid, but dissolves in potash-ley, from which it is precipitated by
acids, and with fine red colour in alcohol, ether, and volatile oils. The
colouring matter of crabs contains 68'18 p. c. C., 9-24 II., and 22-58 0. ;
that of the feet of pigeons and geese is similarly composed. All these
pigments are free from nitrogen (Gobel).

Colouring Matter of the Purple-fish. From Murex brandaris and
M. trunculus. The fresh secretion is colourless, and on exposure to
daylight turns first yellow, then green, blue, red, and finally purple ;
this change of colours takes place with Murex brandaris in two days,
with ^[. tr HIM a I UK in a few minutes.

The thoroughly dried secretion is opaque and black, but yields by
trituration a deep red powder. It smells at first like asafoetida, and
contains copper. Chlorine destroys the colour ; strong nitric acid gives
off nitrous gas and colours it golden yellow. Oil of vitriol destroys
foreign admixtures without attacking the colour itself. Insoluble in
water and in dilute acids, even on boiling; insoluble also in cold
aqueous ammonia, potash, and soda. Boiling potash-ley colours it
yellowish, and deposits green flocks containing some of the undecoin-
posed purple pigment (Bizio, J. Chim. med. 10, 99).

The colouring matter secreted by the sea-owl or lump fish. Aplysia
depilans, a gasteropod occurring on the coasts of the Mediterranean, is


a concentrated solution of aniline-red and aniline-voilet. It decom-
poses very easily in the dissolved state ; if it be precipitated by
sulphuric acid, and again from alcoholic solution by common salt, a
substance is obtained which exhibits the reactions of aniline-violet.
The colouring matter which remains dissolved after the precipitation by
common salt may be separated by tarinic acid, and like fuchsine, is
decolorised by ammonia, and coloured red again by acetic acid (Ziegler,
Mult. Soc. Bull, 37, 293 ; Kojjp's Jahresber. 1867, 821).

On the purple pigment which sometimes makes its appearance on
mouldy articles of food (bread, potatoes, meat), see Sette (Schw. 50,
415); Meylink (Repert. 43, 13), Buchuer (Repert.4&, 88); Pelouze (J.
Chim. med. 19, 586 ; N. Ann. Chim. Phys. 9, 5) ; Ehrenberg (J. Chim.
me'd. Oct. 1849); Oberdorffer (N. Br. Arch. 49, 43); Hiibuer (N. Br.
Arch. 50, 302). According to Erdmann (/. pr. Chem. 99, 385;
Jahresb. 1866, 670), this colouring matter exhibits the reactions
of the aniline dyes, the red that of the salts of rosaniline, and a blue
sometimes observed at the same time, that of the salts of tripheuyl-

On the green colouring of oysters, see Valenciennes (J. Pharm. 27,
155); on the colouring matters of sweat : Schottin (Pharm. Viertelj. 2,
54); Landerer (Repert. 55, 234; Handbuch, viii, 302).

Proteides of the Vegetable Kingdom.

The nitrogenous and sulphuretted substances occurring in the
vegetable kingdom, and formerly designated as vegeto-animal substance,
have more recently been further distinguished according to the follow-
ing considerations.

a. When the dough of wheat-flour is kneaded with water as long
as the water becomes milky from separation of starch, there remains a
grey elastic glutinous mass, the gluten of Beccaria (Common. Bonon. 1, 1,

b. The expressed juice of many plants coagulates when heated, by
separation of a similar substance (Rouelle, Crell. Beitrdge zu den chem.
Ann. 1, 3, 87); the substance thus separated resembles animal albumin t
Vegetable albumin (Fourcroy, Ann. Chim. 3, 252), and gluten (Proust,
J. Phys. 54, 199; A. Gehl 9 *5, 596).

c. Rye-flour yields coagulated vegetable albumin and gluten soluble
in alcohol. When the flour is separated by stirring it up with cold
water and leaving it to settle into sedimentary flour and a solution, the
latter deposits the albumin on boiling, and from the filtrate concen-
trated to the consistence of honey, the gluten may be extracted by
alcohol. The same gluten is obtained when the sedimentary flour is
separated by levigation into starch and a grey substance, and the
latter is exhausted with alcohol (Einhof, A. GehL 5, 131); also Guns-
berg (J.pr. Chem. 85, 214).

d. The wheat-gluten of Beccaria may be resolved, by treatment
with alcohol, into residual zymome and soluble gliadin, which latter is


obtained by evaporating the solution to the consistence of honey
(Taddei, Sckw. 29, 514).

According to this, the insoluble substance (obtained according to c
or d) is to be distinguished from soluble vegetable gelatin (Berzelius).

e. Vegetable gelatin from gluten is accompanied by a mucous sub-
stance, which is obtained by macerating the vegetable gelatin in acetic
acid, mixing with alcohol, and filtering, and remains on the filter in the
form of a transparent gum (Berzelius, Lehrb. 3 Aufl. 6, 453). Accord-

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