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United States Department of Agriculture,

BUREAU OF CHEMISTRY— Circular No. 25.
H. W. WILEY, Chief of Bureau.

COLORING MATTERS FOR FOODSTUFFS AND METHODS FOR THEIR

DETECTION.

[A preliminary report made to the Association of Official Agricultural Chemists.]

By W. G. Berry,

Associate Referee on Colors.

INTRODUCTION.

This preliminary report, including a classification of the colors used
in food products and methods for their detection, is published in its
present tentative form for the purpose of crystallizing what work has
been accomplished in this large field and presenting it for suggestion
and criticism. A basis for future work of a more detailed nature is
thus afforded, and it is hoped that criticisms and contributions to the
subject will be made by those working in this field.

W. D. BiGELOW,

Acting Chiefs Bureau of Chemistry;
Referee on Food Adulteration^ A. O. A. C.
Approved:

James Wilson,

Secretary of Agriculture,

Washington, D. C, August 22, 1905.

CONTENTS. Page.

Scope of the investigation 3

Classification of colors 7

I. Coal-tar color lakes 7

II. Natural colors of vegetable and animal origin 8

III. Organic lakes 13

I V. Mineral pigments 13

V. Coloring compounds 15

Methods of analysis 15

I. Wines , 15

A. Preliminary tests 16

a. Examination for natural or artificial coloring matters 16

Paris municipal laboratory test 17

Dupre test 17

h. Examination for coal-tar colors 17

Mansfield's test 17

Cazeneuve's test 18

Falieres-Ritter test 18

c. Examination for foreign vegetable colors 18

B. Separation and identification of the coal-tar colors 20

a. Method of Sostegni and Carpentieri 20

6. Arata's method , . . 20

c. Wolff-Winterthur method 20

d. Detection of coal-tar colors by extraction with solvents ... 20

Paris municipal laboratory method ,..,,,..,. 20

2

Methods of analysis — Continued. Page.
I. Wines — Continued.

B. Separation and identification of the coal-tar colors— Continued.

e. Special tests for coal-tar colors 21

1. Determination of acid magenta — Girard's method 21

2. Test for Martius yellow or naphthalene yellow 21

3. Test for naphthol colors 21

4. Test for Bordeaux red 21

C. Special tests for vegetable colors 22

a. Detection of caramel — Amthor test 22

6. Detection of turmeric 22

c. Test for cherry juice 22

d. Kermese (Phytolacca) 22

II. Brandy, rum, liqueurs, vinegar, etc 22

General discussion 22

Test for caramel ( Crampton and Simons ) 23

III. Malt liquors 24

Natural and artificial colors 24

Tests for coal-tar colors 24

Tests for vegetable colors 25

IV. Canned vegetables 25

V. Fruits, fruit juices (nonalcoholic), preserves, jam, marmalade, etc... 26

Results on extraction of fruit colors 26

Detection of cochineal 27

VI. Dairy products, fats, oils, etc 27

A. Natural and artificial colors in milk 27

B. Butter, fats, and oils (fresh ) 28

a. Bujard and Baier test 28

h. Vandriken test 28

c. Leeds method 28

d. Special tests (saffron, turmeric, marigold, annatto) 29

1. Martin test 29

2. Carotin test (Moore) 29

3. Test for saffron, curcuma, carotin, and rocou (Cheval-

lier and Baudrimont) 30

4. Test for egg yellow 30

C. Butter, fats, etc. (rancid) 30

D. Milk (fresh) 30

a. Leach's method 30

h. Caramel test (mo(^fication by Blyth of Leach's test) 32

E. Milk (sour), Blyth's method ....* 32

a. Alcohol extract, colored orange, yellow, or brown 33

6. Water extract from the fat 33

F. Cheese 34

VIL Flesh foods 35

Normal and abnormal colors 35

Bujard and Baier method 36

Klinger and Bujard method, modified by Bremer 36

Spaeth method 36

Microscopic examination ( Marpmann ) 36

VIII. Coffee, tea, cocoa, spices, etc 37

Coloring matters considered ,37

Facings 37

Azo dyes 37

Indigo 37

Catechu (Hager's method) 38

Campechy wood 38

- Chicory 38

Sanders wood in cocoa 38

Turmeric in rhubarb 38

Pepper colors 39

IX. Starch preparations (pastry, macaroni, nudeln, etc. ) 39

Colors considered 39

Method for coal-tar colors (Reichelmann and Leuscher) 39

X. Confectionery 39

Colors considered 39

Methods...: 40

SCOPE OF THE INVESTIGATION.

The field of color chemistry is very large, and the chemist in gen-
eral analytical practice often neglects it owing to the vast amount of
time and patience required for an intelligent understanding of the
subject. Much good work has been done toward establishing methods
for the recognition of coloring matters in food stuffs, but with the
data at present available for such work the individual operator will
find himself called upon to exercise his own judgment and apply his
own experience to the subject-matter in hand.

The introduction of coal-tar dyes into the field of food stuffs com-
plicates enormously the scope of the work to be covered in an exami-
nation of artificial coloring. Were it possible to limit the examination
to a certain number of colors, the work would be materially simplified,
but no sooner has the analyst perfected color schemes and tabulated
reactions for the identification of such colors when new ones are found,
rendering previous schemes to a certain extent unreliable and neces-
sarily subject to alteration.

Hence the most that can be hoped for is to establish general methods
for determining whether artificial coloring has been resorted to, and,
if so, whether the coloring matter is of mineral, vegetable, or coal-
tar origin. This fact having been established, special methods must
be applied for the separation and identification of the individual color-
ing matters, often complicated by the presence of mixtures of several
coal-tar colors, rendering color reactions useless until each of the sep-
arate colors has been isolated.

The food chemist may be called upon for an examination of the
coloring matters and commercial preparations used for coloring foods,
and for the examination of foods for* the presence of artificial color-
ings, identification of the added color, and the presence of poisonous
metals due to the latter. He may also be called upon for an opinion
as to the toxic or nontoxic character of the coloring matter, which
not only requires an examination for poisonous metals present, as lakes
and pigments, but in addition the determination of the presence of
poisonous metals due to impurities, the identification of the color or
colors, and a knowledge of the toxic effects of the pure color per se.

An examination, therefore, of the colors and preparations employed
involves the identification of the heavy metals present, the nature of
the color entering into the lake, whether vegetable or of coal-tar

(3)

origin, its identification, and, in the case of mixed colors, their separa-
tion and identification, and, lastly, the presence of poisonous metals as
impurities in the coal-tar dyes, or their presence as inherent constit-
uents of the colors themselves.

Many of the colors contain metallic constituents, as in the triphe-
nylmethane derivatives, especially the greens, such as malachite green,
iodin green, ethyl green, victoria green, etc., which contain a double
chlorid of zinc in combination with the organic matter. Some of the
acridines and thiazines also contain zinc, and naphthol green B contains
iron.

In the preparation of the coal-tar dyes many become contaminated
with arsenic, copper, zinc, tin, lead, etc., from the use of these metals
and their salts during the process of manufacture. Sulphuric acid
being used in some stage of the process of manufacture of nearly all
the dyes introduces the danger of arsenic being present. Hence all
dyes used for artificial coloring which in themselves are harmless
may become injurious from the presence of these poisonous ingredients,
unless highly purified.

While alum lakes of the vegetable colors are in general harmless,
the presence of lakes of tin, antimony, etc., should be carefully
guarded against.

The vegetable colors should be examined for the presence of coal-
tar dyes of a dangerous nature, and for other vegetable colors and
substances and inert mineral matter added for cheapening.

The examination of the food stuffs themselves necessitates deter-
mining whether the coloring is due to natural or artificial means, and,
if' the latter, the color or colors must be separated and an examination
of the material made for heavy metals.

In regard to the toxic effects of the purified coal-tar dyes, the chem-
ist must rely upon the experiments and conclusions of investigators in
this line of work, and should hesitate to express an opinion on a new
color without a physiological test upon living organisms. The experi-
ments of Konig, Weyl, and others should be consulted on this subject.^

FrenzeP found that mandarin (sulphanilic acid azo-B-naphthol) and
metanil yellow (m. benzene sulpho acid, azo-diphenylamin) could
scarcely be considered poisonous in the small quantities in which they
are used in foods, but long-continued, large doses give rise to some
injurious effects.

« Hygiene of Coal-tar Colors, Koster, Heidelberg, 1882; Poisonous Metals in Dyes,
Ashwell and Forth, J. Soc. Chem. Ind., 5, 226, 301; Theerfarben mit besonderer
Riicksicht auf Schadlichkeit u. s. w.. Dr. Thos. Wehl, 1889; The Sanitary Relations
of the Coal-tar Colors, by T. Wehl, Philadelphia, 1892; Effects of Coal-tar Colors on
Digestion, Amer. Chem. J., 8, 1092; Conn. Agr. Expr. Stat. Kept., Winton, 1901,
p. 179.

&Zts. Nahr. Geuussm., 1901, 968-974.

Winogradow^ ascertained that the following dyes hindered the
digestion of albumen by pepsin, even when only a few milligrams
of the colors were present (an amount corresponding to from one-
tenth to one one-hundredth of the digestive solution), this action being
almost inhibitive:

Safranin. Cceruleine S. Magdala red.

Ponceau RR. Phloxin RBN. Azoflavin.

Azofuchsin G. lodoeosin. Benzopurpurin.

Orange II. Chrysanilin. Cerise.

The following interfered less than the first-mentioned dyes, but in
every case some effect was noticed:

Acid green. Anilin green. Martins yellow,

lodin green. Primulin. Metanil yellow.

Acid azo yellow. Auramin O. Quinolin yellow.

Yellow T. Anilin orange. Methylene green.
Naphthol yellow.

The methods of separating the colors from the material to be exam-
ined by the use of solvents involve the separation of the natural colors
at the same time, and these must first be isolated before identification
tests can be applied. This fact naturally necessitates a very compre-
hensive knowledge of the color reactions and the behavior of the
natural colors with reagents. Complete data on this subject are as yet
wanting.

The coal-tar dyes may, in general, be most satisfactoril}^ separated
by the double-dyeing method, with or without previous extraction
with solvents, as the case may be, and in some cases niiay be identified
directly by tests on the dyed fabrics, or more accurately f)y being
removed from the fabric and subjected to purification. Great care
and judgment must be exercised in applying the color reactions and
arriving at a conclusion therefrom, as the presence of more than one
dye, or some organic impurity, will lead to erroneous results. Several
means of identification should be tried and a conclusion drawn only
when the analyst is perfectly satisfied of the identity of the dye.

Many of the results obtained in the determination of a dj^e have
been rendered ambiguous, owing to confusion of names applied to the
same dye, and the analyst should always make a point of identifying
any particular dye by giving the name of the original manufacturers,
so that its composition may be known; as, for instance, orange Gr
might be either of the following in default of a distinguishing mark,
viz:*

Orange G (C. J.). Anilin azo /? naphthol.

Orange G (B). Anilin azo 2 naphthol, 6.8 disulphoacid sodium salt.

Orange G (H.) Sulphanilic acid azo ft naphthol sodium salt.

«Zts. Nahr. Genussm., 1903, 689.

& Rawson, Gardner, and Laycock, Dictionary of Dyes, Mordants, etc., 1890; Schultz
and Julius, Tables of Dyes.

6

For convenience the finally completed subject might be treated in a
systematic arrangement under the following headings, viz:

I. Remarks in general on coloring matters liable to be present in food stuffs.
II. Colors to be considered.

(1) Coal-tar colors, with their composition, commercial designations, and

synonyms.

(2) Vegetable colors, their botanical origin, common names, etc.

(3) Mineral colors and pigments.

(4) Organic lakes.

III. Harmless and harmful colors and dyes, so far as known.

IV. Commercial coloring compounds.

V. Grouping of food stuffs into general classes for examination, as follows:

(1) Butter, oils, milk, cheese, etc.

(2) Flesh foods.

(3) Canned vegetables.

(4) Starch foods (noodles, macaroni, etc.).

(5) Vinegar.

(6) Confectionery.

(7) Wines and spirituous liquors, fruit sirups, etc.

(8) Brandy, liqueurs, etc.

(9) Beer, malt liquors, etc.

(10) Tea, coffee, spices, etc.

(11) Medicinal preparations.

(12) Cosmetics, soaps, etc.

(13) Miscellaneous material (tags, paper linings, etc.).

Each class may be treated under the following heads:

(a) Natural or artificial coloring.

(b) Mineral or organic coloring.

(c) General methods in detail for detecting the organic coloring

matter, and, if possible, isolation of same for identification
by tabular schemes.

(d) Special tests for colors.

VI. Each of the thirteen classes in detail, under heads as given under V.
VII. Original work on behavior of coloring matters, with solvents and reagents.
VIII. Tabular schemes for the identification of the isolated coloring matters.
IX. Addenda (what colors allowed, laws, etc. ).

It is suggested that the members of the association and collaborators
interested in the subject of colors be invited to do what original work
their time will permit, on the points suggested below, and communi-
cate their results to the associate referee from time to time as oppor-
tunity permits.

(1) Solubility of the coal-tar and vegetable dyes in various solvents (ether, acetic
ether, petroleum ether, methyl and ethyl alcohols, acetone, etc.) , arranged according
to their solubility — as, easily soluble, difficultly soluble, and insoluble.

(2) Extractive values of the various solvents for dyes in neutral, acid, and alkaline
solutions.

(3) Characteristics of the coloring matters as contained in fresh fruits, vegetables,
wines, etc., with reagents and solvents, with their respective dyeing properties.

(4) Testing such new schemes as may appear in the various current chemical
journals, and such as have appeared during the last few years.

This synopsis, together with the classification of colors and the
methods of analysis which follow, is intended as an outline for the
examination of food stuffs for colors, to be elaborated during the
progress of the work.

CLASSIFICATION OF COLORS.

As a guide to the food analyst, a compilation is given of the vege-
table and animal colors, lakes and pigments, which he may be called
upon to examine either as to composition and origin or as to suitabil-
ity for food colors. Many of the old vegetable colors have, of course,
been discarded for the coal-tar d^^es now employed, which are also

classified.

I. Coal-Tar Color Lakes. «

1. The principal materials used in the preparation of lakes from acid dyes are:

Barium chlorid.
Lead nitrate and acetate.
Zinc sulphate.

Aluminum sulphate and acetate and potash, sodium and ammonium alums.
• Tin chlorid.

Antimony chlorid, tartar emetic, double flourids of antimony and sodium or

potassium.
Calcium nitrate and acetate.

2. Those from basic dyes are:

Tannic acid.

Phosphate of soda.

Sodium arsenite.

Stannic and stannous acids and salts.

Antimony acids.

Resinic and various fatty acids. %

3. Principal bases used to modify the color and physical properties of lakes are:

Barium sulphate (barytes, blanc fixe, heavy spar).

China clay (kaolin).

Calcium sulphate (Paris white, satin white, gypsum).

Kieselguhr (infusorial earth).

Red lead.

Zinc ox id.

Lead sulphate.

Aluminum hydrate.

Aluminum arsenite.

Barium phosphate.

Lead carbonate.

Calcium phosphate.

Lampblack and vegetable black.

Green earth.

4. Colors used may be classed under:

(1) Acid triphenylmethane colors.

(2) Basic tryphenylmethane colors.

(3) Azo colors.

(4) Oxy ketone colors.

(5) Azin colors.

« Jennison, Manufacture of Lake Pigments, 1900.

A. RED LAKES.

Magenta and magenta reds.

Rhodamin B, G, S, 6G, 12G.— Bluish red to reddish pink.
Safranins.

Ponceau 4GBL. — Yellow.
Ponceau GL, GR. — Medium yellow.
Ponceau 4R. — Blue.
Scarlet 3R.— Blue.
Fast red 0. — Deep blue.
Reds and maroons from the last four mixed.

Eosins, phloxins, rose bengal— vermilionettes, alizarins— red, scarlet, brown,
maroon.

B. ORANGE LAKES.

Mandarin R, G. — Brilliant orange Orange II. O, R. — Ponceau 4GBL.

RG.

a YELLOW LAKES

Auramin. Metanil yellow.

Thioflavin T. ' Quinolin yellow.

Naphthol yellow S. Tartrazin.

D. BROWN LAKES.
Bismarck brown. Acid brown B.

E. GREEN LAKES

Acid green D. Diamond green.

Ethyl green. Coeruleine.

F. BLUE LAKES.

Nile blue A. Diphenylamin blue.

Victoria blue. Patent blue BN.

Naphthalin blue. Erioglaucin blues.

Methylene blue B. Basle blue.

Alkali blue D. New blue.

Neutral blue. Water blue.

G. VIOLET LAKES.
Methyl violet B. Gallein.

Rhodamins.

H. BLACK LAKE.
Acid black FHA.

II. Natural Colors of Vegetable and Animal Origin.

The following list has been compiled from various sources and,
as far as possible, verified by consulting botanical literature and by
free reference to Dr. Hans Rupe's ''Die Chemie der natiirlichen
Farbstoffe" (Braunschweig, 1900):

Alder bark: Source — Alnus glutinosa. Yellow.

Alkanet: Source — Baphorhiza tinctonn {Alkanna tindoria Tausch.; Anchusn tine-
tor la L.). Used in coloring medicines, oils, pomades, wine, etc., red to crimson.
Alkanna green has also been prepared from the root. «

tij. Soc. Chem. Ind., 1903, 512.

9

Aloes: Source — Cape aloe, Aloe spicata; A. arborescens; A. lucida; A. succotrina;
A. vera. Yellow.

Al root; or Aich root, sooranjee (India), suranjee (India): Source — Morinda citrifolia;
M. tinctoria. Alumina lake, yellow.

Annatto; or anotto, orlean, roucou, orenetto, attalo, terra orellana, achiote: Source —
Bixa orellana. Used for coloring oils, butter, etc.

Archil; or orchil, orseille, oricello, orchilla: Source — Rocella montagnei (new); R.
fuciformis (old); R. tinctoria. Also prepared from any lichens containing orcin
or its derivatives, i. e., variolaria, lecanoria, evernia, cladonia, ramalina, usnea.
Appears in liquid, paste, and powder, the latter form being a sulphonated de-
rivative. Dyes unmordanted wool in neutral, alkaline, and acid solutions, and
should not be mistaken for coal-tar dyes, in the double dyeing test.

Asbarg; or gandhaki (Afghanistan): Source — Delphinium zalil. Yellow lakes pre-
pared from the blossoms.

Bahia wood: Source — Caesalpinia brasiliensis. Exported from Bahia. Sometimes
called Brazil wood. See under Redwoods.

Barberry: Source — Berberis vulgaris. Yellow basic dye.

Barwood; or camwood, kambe wood, bois du cam: Source — Baphia nitida. From
west coast of Africa and Jamaica. See under Redwoods.

Bastard hemp: Source — Datisca cannabina. Alkaline solutions yellow.

Bilberry; or whortleberry: Source — Vaccinium membranaceum; V. myrtillus. Blue
to purple.

Box myrtle; or yangmoe, of China; kaiphal, of India: Source — Myrica nagi {M.
sapida Wall, and M. integrifolia Roxb. ) ; M. rubra. Alumina lake, brown orange.

Brazilwood; or fernambourgwood, pernambuco wood, fernambuck wood, bois de
fernambouc, rothholz: Source — Gmlandina crista; Caesalpinia braziliensis.
Chiefly from Brazil and Jamaica. See under Redwoods.

Brazilettowood ; or Jamaica redwood, Bahama redwood: Source — Balsamea sp. See
under Redwoods.

Buckthorn: Source — Rhamnus cathartica. Purple juice which when treated with
alkali becomes green. Used in confectionery as sap green.

Buckwheat: Source — Fagopyrum fagopyrum. Yellow color from leaves and stalk.

Buttercup: Source — Ranunculus bulbosus and other species. Yellow.

Cabbage: Source — Brassica oleracea. Contains cauline, probably identical with the
cyanin of wine.

Camwood; or gaban wood, poa-gaban: Source — Closely allied to barwood. From
African coast. See under Redwoods.

Capers: Source — Capparis spinosa. Yellow.

Caramel: Source — From sugar. Brown.

Carrot: Source — Daucus carota. Yellow.

Catechu: Source — Acacia catechu; Ourouparia gambier. Brown to red colors. Influ-
enced by oxidation. Contains catechin.

Celery; or smallage: Source — Apiam grareolens. Yellow green.

Chamomile (Ger. ); or matri carlo: Source — Matricaria chamomilla. Alumina lake,
yellow.

Chay root; or che root, cherri vello, sayavee, imbural, turbuli: Source — Oldenlandia
umbellata. Contains alizarin, purpurin, etc.

Chelidoine juice: Source — Chelidonium majus. Yellow.

Chica-red; or crajina, carajara: Source— Arrabidasa chica {Bignonia chica Humb. and
Bonpl.). Vermillion red powder insoluble in water, alkaline solutions, orange
to red.

Chinese green; or lokao: Source — Rhamnus tinctoria; R. dahurica. Only natural
green dye other than chlorophyll.
9251— No. 25—05 2

10

Chinese yellow: Source — Gardenia grandiflora. Other Chinese yellows are Wongsky,

VVougshy, Wongschy, Hoang-tchy, Hoang-teng, Hoang-Tschi, Hoang-pe-pi, and

Ti-hoang.
Chrysamic acid: Source — Aloes. Action of nitric acid on aloes. Yellow in alcohol.
Chlorophyl:: Green color of plants.
Cochineal; or cochenille, coccionella: Source — Coccus cacti (dried bodies of the female

insect). Contains carminic acid soluble in water with purple color; lakes, red

to purple; alum or tin lakes, cochineal carmine or coccerin.
Cotinin: Preparation from young fustic. Yellow.
Cranberry; or red bilberry: Sjurce — Vacciniurmitisidaea L,. Red.
Cudbear; orcudbeard, perseo: Source — Lecanora tinctoria; Variolariaorcina. Differs

from archil in being in powder form and free from excess of ammonia.
Cyanin: Coloring matter from petals of flowers. Occurs in wine. Blue, turning

pink with vegetable acids.
Dragon's blood (palm): Source — Daemonorops draco. Red resin.
Dragon's blood (Socotra): Source — Dracaena dnnabari. Red resin.
Dwarf elder: Source — Samhucus ebnlus. Red.
Dyer's broom: Source — Genista tinctoria. Yellow.

Dyer's woodruff: Source — Asperula tinctoria. Contains colors similar to alizarin.
Elderberry: Source — Sambucus canadensis; S. nigra; S. pubens. Red.
Fairy cup; or blood cup: Source — Chlorosplenium aeruginosum. Calcium lake, green.
Flavin: Prepared from oak bark. Olive yellow to dark brown powder.
Forget-me-not: Source — Myosotis palustris. See Cyanin.
French purple: Prepared from archil by treatment with acid.
Fustic (old); or yellow Brazil wood, Holland yellow wood, murier des teinturiers,

bois jaune, Gelbholz: Source — Chlorophora tinctoria {Morus tinctoria L.; Madura

tinctoria D. Don. ) Contains morin and maclurin. Yellow.
Fustic (young); or bois jaune de Hongrie, du Tirol, Fisetholz, fustel: Source — Coti-

nus cotinus {Rhus cotinuslj.). Contains fisitin. Yellow.
Galangal (Javan): Source — Alpinia galanga. Alkaline solutions yellow.
Galangal (Chinese): Source — Alpinia officinarum. Alkaline solutions yellow. Used

in Russia for making " Nastoika," a liquor.
Gamboge: Source — Garcinia hanburyi; G. morella. Red resin. Lakes, yellow.
Garancin: Formerly prepared from madder. Of historical interest only.
Gentian: Source — Gentiana lutea. Alkaline solutions yellow.
Goa powder: Source — Vouacapoua araroba {Andira araroba) Aguiar. Contains

chrysarobin and chrysophanic acid. Yellow.
Golden seal; or Canadian yellow root: Source — Hydrastis canadensis. Yellow basic

dye.
Harmalared: Source — Peganum harmala. Basic color insoluble in water; alkaline

solutions red.
Heartsease; or pansy, lady's delight: Source — Viola tricolor arvensis. Yields quer-

cetin. Yellow.
Hollyhock: Source — Althaea rosea; Malva sylvestris; M. rotund) folia. Solutions, violet

red. Crimson with acids. Green with alkalies. Alumina lake, violet blue.
Horse chestnut: Lakes, yellow.
Indian yellow; or piuri, pioury, purree, purrea arabica, jaune indien. Prepared in

India from the urine of cows fed on mango leaves and contains yellow coloring

matters, free and in form of magnesium or calcium salts.
Indigo: Source — Indigofera anil and other varieties. Insoluble in water. Becomes

soluble by treatment with sulphuric acid, forming sulpho salts. Indigo carmine

(blue).
Jack wood; or jack fruit of Ceylon: Source — Artocarpus integrifolia. Alumina lake,

yellow.

11

Kamala; or kameela, ramelas, rottlera: Source — Echinus philippensis {Rottlera tinctoria
Roxb). Red powder,

Kermes berries; or portugal berries, poke berries, pigeon berries, scoke berries:
Source — Phytolacca americana {Phytolacca decandra L. ). Reddish.

Kermes; or false kermes berries, grains de kermes, vermilion vegetal: Source — Coc-
cus ilicis (dried bodies of the female insect). Solutions and lakes, blood red.

Kino: Source — Pterocarpus marsupium; Butea frondosa, B. superba, and varieties;
Eucalyptus corymhosa. Red color.

Lac-dye; or lac-lac: Source — Coccus laccx (from the female insect). Colors similar
to cochineal.

Lapacho; or taigu wood: Source — Tecoma lapacho and allied species. Yellow color.

Lima wood; or Costa Rica redwood: Similar to St. Martha wood. See under Red-
woods.

Liquorice: Source — Glycyrrhiza glabra. Brown.

Litmus; or tournesol: Source — Rocella, Lecanora, Variolaria. Red and blue.

Logwood; or Campechy wood, Blauholz: Source — Haematoxylum campechianum.
The unfermented extract forms yellow solutions if neutral, and blood-red solu-
tions with calcareous water. The unfermented solution contains chiefly a glu-
coside which upon fermentation yields hsematoxylin, and the latter is easily
oxidized to hsematein. Various colored lakes are formed. Hsematoxylin forms
rose-red color with alum and a black violet lake with iron alum. Hsematein
forms bluish violet with alkalies; reddish purple with sodium carbonate; reddish
purple with ammonia; bluish violet lake with ammoniacal copper sulphate;
violet lake with ammoniacal tin chlorid; black with ammoniacal iron alum.

Lopez root: Source — Toddalia aculeata. Contains berberin. Yellow.

Lomatiol: Source — Tricondylus ilidfolia; Tricondylus myricoides. Yellow.

Madder: Source — Rubia tinctorum. Natural source of alizarin dyes.

Mang-koudur; or oungkoudon, song-kou-long, jong koutong: Source — Morinda um-
bellata. Lakes, yellow to red.

Marsh marigold: Source — Caltha palustris. Yellow\

Mountain wormwood; or Genepi des alpes: Source— ^r^emma absinthium. Yel-
lowish.

Munjeet: Source — Rubia cordifolia. Similar to madder.

Myrtle berry: Source — Myrtus communis. Bluish red.

Nettle: Source — Urtica sp.

Nicaragua wood : Source — Guilandina echinata. Boughs or twigs used. See Red-
woods.

Onion: Source — Allium cepa. Alumina lake, yellow brown.

Oregon grape root: Source— 5er6em aguifolium. Yellow basic dye.

Panama crimson: Source — Vine called China.

Parsley: Source — Apium petroselium. Alumina lake, yellow.

Peach wood; or St. Martha wood, Martin wood, bois du sang: Source — Guilandina
echinata. From the Sierra Nevada in Mexico. See under Redwoods.

Persian berries; or yellow berries, Kreutzbeeren, Avignon- Korner, granes de perse,
graines jaune, graines d' Avignon {Rhamnus infectoria), French berries {R.
alaterna), Spanish berries {R. saxatilis), Italian berries {R. infectoria), Hunga-
rian berries {R. cathartica) : Source— Species of Rhamnus as given above. Alum
lake, bright yellow; iron lake, dark olive.

Poppy; or field red corn: Source— Papatwr/ioeos. Red.

Poplar buds: Source— Populus sp. Alumnia lake, yellow.

Prickly pear: Source— Opwn^ia opuntia. Red.

Privet berries: Source — Ligustrum vulgare. Bluish red.

Purple heart: Source— Copaiva pubijlora. Alum lake, yellow.

12

Puriri: Source — Vitex Uttoralis. Alum lake, yellow.

Quercitron: Source — Quercus velutina and varieties. Yields quercetin, yellow.

Quebracho: Source — Quebrachia lorentzii. Yellow color.

Redwoods: See Brazil, Bahia, Peach, Nicaragua, Sapan, Lima, Braziletto, Bar, and
Camwood. These woods yield on treatment various red to yellow-red colored
solutions, no two woods giving exactly the same shades, i. e., Brazilin, proba-
bly occurring as a glucoside, forms Brazilein on oxidation and yields lakes sim-
ilar to alizarine. Florence, Berlin, and Venetian lakes are lakes of the soluble
redwoods.

Rhubarb: Source — Rheum offidnaJe. 'Yields chrysophanic acid, yellow.

Rue: Source — Euta graveolens. Alum lake, yellow.

SaflElower; or dyer's saffron, carthame, safran bdtard, bastard saffron: Sburce —
Carthamus tinctorius. Yellow color. Triturated with French chalk and dried,
forms various bright red "rouges."

Saffron; or azafran (Afgh.): Source — Crocus sativus. Yellow.

Sag6: Source — Salvia officinalis. Yellow.

Sandalwood; or santalwood, lignum santalum, red santalwood, Saunders wood, red
sandalwood, red Sanders wood, bois de santal, Sandelholz: Source — Pterocarpus
santaUnus; P. indicus. Contains santalin, a fine red powder easily soluble in
alcohol and acetic acid with a blood-red color. See under Redwoods.

Sapan wood; or sappan wood, Japan wood, bois du Japon, also called red sandal-
wood, santalwood, sumbawa wood: Source — Caesalpinia sapan. Probably iden-
tical with caliatur wood or cariatur wood. See under Redwoods.

Saw-wort: Source — Serratula tinctoria. Alumina lake, yellow.

Sepia: Source — Sepia officinalis. Dark-brown ink-like pigment.

Sorgo red; or durrha: Source — Andropogon sorghum. Lakes, crimson red.

Spanish trefoil: Source — Trifolium sp.

Spinach: Source — Spinacia oleracea. Yellow.

Stringy bark: Source — Eucalyptus macrorhyncha. Orange to yellow.

Sun dew : Source — Drosera ivhittakerii. Lakes red to brown.

Sumac (Cape); or pruim bast: Source — Colpoon compressum. Alum lake, yellow.

Sumac (Sicilian) : Source — Rhus coriaria. Alum lake, olive yellow.

Tyrian purple: Source — Murex, purpura, buccinium, etc. (sea shells).

Turmeric; or curcuma, Indian saffron, terra merita, souchet, safran d'Inde: Source —
Curcuma longa; C. rotunda. Yellow color.

Ventilago Madras-patana; or oural patti, pitti, lokandi, kanwait, etc.: Source —
Ventilago madraspatana. Lakes, blue.

Virginia creeper: Source — Parthenocissus quinquefolia. Red color.

Waifa; or hoai-hoa, Chinese yellow berries: Source — Sophora japonica. Alumina
lake, yellow.

Wall flower: Source — CJieiranthus cheiri. Yellow lakes prepared from the blossoms.

Wall lichen: Source — Parmelia parietina. Yellow.

Waras: Source — Moghania congesta {Flemingia congesia Roxb. ). Red resinous
powder.

Weld; or wau, gaude, yellow weed, dyer's rocket: Source — Reseda luteola. Alumina
lake, yellow.

Whitethorn; or blackthorn: Source — Crataegus oxyacantha. Yellow lakes from
blossoms.

Woad; or pastel, waid: Sourcer-Isatis tinctoria; I. lusitanica. Contains indigo.

A large number of vegetable substances contain coloring matters,
but are too numerous to mention and are of little interest commercially
as yet. Among these the following may be mentioned, their coloring
matters having been to some extent studied.

13

Ruta graveolens, Robinia pseudacacia, Rhodosphaera rhodanthema, Rumex ohtusifolius,
Arctostaphylos uvaurd, Polygonum cuspidatiim (in China Kan-yen or Wii-tzu), yellow;
Aristotelia maqui, red; Evodia meliaefolia, yellow.

III. Organic Lakes.
YELLOW.

Alum lakes from various species of buckthorn (Rhamnus), Dutch pink being that
from Persian berries and commercial Dutch pink that from mixtures of yellow ber-
ries, quercitron, and turmeric. Alum lake from Dyer's weld {Reseda luteola). Alum
lake of gamboge crude or ** prepared" (freed from impurities), alum lakes of quer-
citron, young and old fustic, barberry, annatto, turmeric, saffron, safflower, purree
or Indian yellow, and Gardenia grandiflora. Quercitron alone is seldom used.

RED.

Ammonia compound of cochineal (carmine). Ammonia and alum lake of cochi-
neal- (Munich, Vienna, Paris, or Florentine lake). Soda compound of safflower
(saffron carmine). Alum lakes of Lac, and Chica, Brazil, Bahia, St. Martha's,
Lima, Sapan, and sandalwoods and alizarin.

BLUE.

Alum lake of indigo sulphonic acid (new blue, indigo extract, etc.).

GREEN.

Alum lakes of chlorophyll, unripe Persian berries (sap-green, "bladder green"),
lokao, and lime compounds of buckthorn (Charvin's green).

VIOLET.

Lime compounds of lokao and archil (French purple). Alum lakes of alkanet
and logwood.

IV. Mineral Pigrments. «
YELLOW.b

Active ingredients.

Chrome yellow Pb. Cr.

Cassel yellow \

Mineral yellow iPb. Cr.

Veronese yellow J

Montpelier yellow Pb. Cr.

Turner's yellow ^

English yellow ]^^' ^^^

Naples yellow Pb. Cr.

Antimony yellow Pb. Sb. Bi.

Calcium chrome yellow . Cr. Ca.

Barium yellow \

Yellow ultramarine iCr. Ba.

Permanent yellow J

«Bersch, Manufacture of MineraTand Lake Pigments, 1901; also consult, in this
connection, an official list of prohibited colors in Braunschweig, Zeit. offent. Chem.,
1898, p. 453, and Vereinbarungen . . . Nahrungs-und Genussmitteln fiir das Deutsche
Reich, Berlin, 1897.

ft Bracketed colors are synonyms.

Active ingredients.

Zinc chrome yellow Zn. Cr.

Cadmium chrome yellow- Cd. Cr.

Cadmium yellow Cd. S.

Mars yellow Fe. Ca. Al.

Siderin yellow Fe. Cr.

Aureolin yellow Co.

Turpeth mineral yellow . Hg.

Realger yellow As.

Orpiment yellow i

King's yellow / ^'

Mosaic gold Sn.

14

Vermilion Hg.

Antimony vermilion Sb.

Hematite Fe.

Vogel's iron red Fe.

Macay's English red Fe.

Indian red Fe.

Chrome red ^

Chrome vermilion j

Cr.

Fe. CN.

Persian blue

Chinese blue

Berlin blue

l^aris blue

Brunswick blue

Mineral blue

Turn bull' s blue Fe. CN.

Antwerp blue Fe. CN.

Ultramarine ALSiOg

Bremen blue Cu.

■}as. Cu.
■}as. Cu.

Scheele's green

Swedish green

Brunswick green . .

Green verditer

Neuweid green As. Cu.

Bremen green Cu.

Emerald green As. Cu.

Verdigris Cu.

Mitis green • Cu.

Kuhlmann's green Cu.

Eisner' s green Cu.

Casselmann's green Cu.

Lime green Cu. As.

Patent green Cu. As.

Egyptian blue green Cu.

Chromium chlorid Cr.

Manganese violet. .
Nuremburg violet .
Tin violet Sn. Cr.

JMn.

RED.

Chrome orange . . .

Persian red

Derby red [►Pb. Cr.

Chinese red

Indian red

Cobalt red Co.

Cobalt magnesium red . . Co. ]5lg.

BLUE.

Newberg blue ^

Lime blue ICu.

Payen's blue J

Oil blue Cu.

Cobalt blue

Thenard's blue

King's blue >Co. Al.

Leyden blue

Cobalt ultramarine

Coeruleum Co. Sn.

Blue ashes Cu.

Mountain blue Cu.

GREEN.

Chrome green Cr.

Guignet's green Cr.

Emerald green Cr.

Turkish green Cr.

Leaf green Cr.

Arnaudan's green Cr.

Plessy's green Cr.

Schintzer's green Cr.

Cobalt green Co.

Manganese green 1

Rosenstiehl's green / " ^^'

Bottger's green Mn.

Silk green Pb.

Natural green Cr. , picric acid.

Nonarsenical green Cu. Cr. Fe.

VIOLET.

Mineral lake Sn. Cr.

Copper violet

Guyard's violet . . .

Zn.

Ba.
Ba.

}cu.

BROWN.

Copper brown Cu.

Hatchett brown Cu. CN.

Chrome brown 1 Cu. Cr.

Cobalt brown Co. Fe.

Lead brown Pb.

Manganese brown Mn.

Pyrolusite brown Mn.

Prussian brown Fe. CN.

Iron brown Fe.

A comprehensive list of the commercial names of pigments, with their
synonyms in English, French, German, and Latin, will be found on
page 460 of Bersch's work on pigments.

15 [ ■•'l*''^

V. Coloring Compounds.

Name. Use. Said tx) contain.

Carottine Butter Solution of 1 part annotto in 4 parts oil.

Orantia Butter Mixture of annotto and sodium carbonate.

Beer color Beer Starch, sugar, NajCOs; soluble in 75 per centalcohol.

Vinoline Wine Mixture of reds, usually rosanilin salts.

Bordeaux- Verdisant. Wine Methylene blue, diphenylamin orange, fuchsin S.

Teinte de Fismes Wine Elderberry juice, alum.

Teinte Bordelaise . . .Wine Currant sirups, 4 per cent alcohol.

Saffron substitute Wine Nitro-cresol, potash salt, 40 per cent sal ammoniac.

Onocyanin Foods Thick liquid ; gives reaction for wine color; con-
tains 74 mg. copper « per liter.

Sanguis Sausages Contains red coal-tar dye similar to ponceau.

Rosalit Sausages Ammoniacal solution of carmine and saffran

extract.

Macilin Meat Wheat starch, potato starch, azo dye.

Albo-Carnit Sausages Faintly colored solution of sugar 4.4 per cent,

KNO3 1.5 per cent, NaCl, and boric acid.

Rubro-Carnit Sausages Coal-tar dye in H2O, 3.5 per cent.

Roseline Sausages Carmine.

Brilliant berolina . . . Sausages Ponceau 2G.

Blutroth, meat juice. Meat Ponceau 2R.

Krebsfarbe » Meat Orange G.

Wurstroth .Sausages Eosin.

Darmrothe Sausages Orange II or Mandarin G extra, sodium salt of sul-

phanil ( or toluidin sulpho-acid) , azo-B-naphthol.

Krebsfarbe Sausages Ponceau RT.

Zanzibar carbon Meat Coal-tar dye similar to Vesuvin or Bismarck brown.

Freeze-Em Dye similar to tropseolin.

METHODS OF ANALYSIS.
I. Wines.

The natural coloring matter of red wine is cenolin, similar in its
properties to anchusin of alkanet. There is also said to be a blue color
present identical with the cyanin of flowers. The varying depths of
color in red wines is probably due to the coloring matter contained
respectively in the pulps and the skins of the grapes emplo3^ed, usuall}^
to the latter source.

The coloring matter of the pulp is very similar in its properties to
that of the black currant, elderberry, and bilberr}^ making these lat-
ter very diflicult if not wholly impossible to detect when present in
wines. The examination of a wine for artificial coloring ma}" cover
the entire range of vegetable colors and include a very long list of the
coal-tar colors, although in most cases these colors are confined to a
comparatively limited area; a certain class of red coal-tar colors being
much more frequently met with, as the usual added coloring matter
(when colored at all), i. e., ponceaus, tropaeolins, oranges, Biebrich
scarlets, etc. , belonging to the azo dyes and the saf ranins of the tri-
phenylmethane series.

«Zts. Nahr. Genussm., 1904, 354.

16

A. PRELIMINARY TESTS,
a. Examination for Natural or Artificial Coloring Matters. «

Reagent.

Reactions for normal wine.

Reactions for suspicious wine.

1. Add ammonia to 20 cc of wine

until alkaline, then a few
drops more, agitate, pour
into glazed i>orcelain dish.

2. Add subacetate of lead in

slight excess to 20 cc of wine,
about 6 cc to 8 cc, agitate
and Alter.

3. Add 6 cc of 10 per cent solu-

tion of alum to 10 cc of wine,
to which has been added
previously a weak solution
of potassium carbonate (until
the color does not deepen),
then add 5 cc of a 10 per
cent solution of potassium
carbonate. (Neutralization
must be assured.)

4. Add 10 cc of saturated solu-

tion (in the cold) of alum to
10 cc of wine, and then, drop
by drop, a concentrated solu-
tion of neutral acetate of
lead until precipitation is
complete, and filter.

5. Agitate 10 cc of ether and 10 cc

of wine in a test tube.

6. Add 10 cc of solution of alum

— 2° B. to 10 cc of wine pre-
viously brought to a violet
tint by addition of potassium
carbonate.

7. Small bit of fulminating cotton

is placed in a tube with 20 cc
of wine and agitated for a
minute or two, well washed
with distilled water, and
dried.

8. Fifty cc of wine made just

alkaline with baryta water,
then 25 to 30 cc of neutral
amyl alcohol. Agitate sev-
eral times and allow to settle.

9. Add 40 centigrams of yellow

oxid of mercury finely pul-
verized to 20 cc of wine,
heat to boiling, and filter
through double filter paper.

10. Equal weights of dioxid of

manganese natural, pulver-
ized, and wine are agitated
for 5 minutes, then filtered.

11. Boil a small piece of flannel,

well bleached and washed,
with 20 to 30 cc of wine;
evaporate to dryness, wash
flannel with distilled water,
and observe the color; then
treat with ammonia.

Greenish blue; green or yel-
lowishgreen; yellowish with
some brown (old wine).

Precipitate varying from gray-
ish blue to greenish blue or
gray; filtrate colorless.

Lake colored bottle green with-
out blue or violet tint; filtrate
uncolored, green, or lilac, in
the latter case becoming
green on adding sodium car-
bonate.

Filtrate light wine color

Ethereal layer colorless ,

Mixture wine-«olored lilac,,
very intense, or garnet.

Cotton white or faint wine red,
becoming green with am-
monia.

Amyl alcohol colorless, a fil-
tered portion remaining so
when acetic acid is added.

Filtrate colorless, remaining so
after adding acid; residue,
treated successively with
boiling water, alcohol, and
amyl alcohol, does not color
either solvent.

Filtrate colorless or yellow
tinted.

Wool faintly colored like wine
lees; treated with ammonia
yellowish green.

Red brown; garnet; reddish
black; reddish green.

Precipitate deep green, green,
red green, or grayish red;
filtrate uncolored, or more
often colored.

Lake is colorless, violet, or rose;
filtrate is blue, violet, or rose,
and does not turn green on
adding potassium carbonate.

Filtrate blue, violet, gooseberry
blue.

Ethereal layer yellow or violet.
Ammonia added to the ethe-
real layer gives yellow to red
(campechy), violet to deeper
violet (archil).

Mixture violet blue.

Cotton rose, red brown, or blue,
disappearing on addition of
ammonia and not becoming
green.

Amyl alcohol colored, or be-
comes colored rose, yellow,
or violet with acetic acid.

Filtrate colored, or becoming so
when acidified; residue treat-
ed in same manner with sol-
vents colors some or all of
them.

Filtrate rose color.

Wool colored.

oMM. Fortes et Ruyssen, Traits de la Vigne.

17

Paris municipal laboratory test.f^

Three preliminary tests are used, and wines are considered genuine
as to color if they respond to these tests.

(1) Sticks of chalk are steeped in a 10 per cent solution of egg albumen and dried
first in the air and* then at 100° C. The wine is tested by allowing two drops to fall
on a surface of the chalk from which the excess of albumen has been removed by
scraping. Genuine wines give a gray color, and young and highly colored wines
may give a somewhat bluish tint, but there should be no trace of green, violet, or rose.

(2) The wine is made alkaline by baryta water until it is of a greenish hue. It is
then shaken up with acetic ether or amylic alcohol. If the wine is pure there is no
color in the upper layer, with or without the addition of acetic acid. On the other
hand, coal-tar colors of a basic nature color the solvent and give indications suggestive
of amido-benzene, fuchsin, safranin, etc.

(3) Ten cc of wine are made alkaline until the wine becomes of a green color by
the addition of a 5 per cent caustic potash solution. To this are added 2 cc of a solution
of mercurous acetate. The whole, after shaking, is filtered. With pure wine the
filtrate is colorless, both before and after acidulating with hydrochloric acid, while
coal-tar colors of an acid nature tint the filtrate red or yellow.

Dupre test. ^

A jelly is made by dissolving 5 grams of gelatin in 100 cc of warm water and
pouring the solution into a square fiat mold made of paper. From this cake cubes
about three-fourths inch square are cut with a sharp wet knife and are immersed in
the wine, taken out after the lapse of from twenty-four to forty-eight hours, washed
slightly, and sections cut, in order to see how far the coloring principles have pene-
trated. If the wine is pure, the color will be confined almost entirely to the edges of
the slice, or will not have penetrated beyond one-sixteenth to one-eighth of an inch.
Most other coloring matters rapidly permeate and color the jelly.

(1) Colors penetrating slowly:

Coloring matter of pure wine.
Coloring matter of rhatany root.

(2) Colors penetrating rapidly:

Rosanilin. Litmus,

Cochineal. Red cabbage.

Logwood. Beet root.

Brazil wood. Wayside mallow.

Indigo. Marsh mallow.

b. Examination for Coal-Tar Colors.
Mansfield^ s test. <^

Dilute 25 cc of red wine in two large test tubes to 100 cc with water. Add a few
drops of hydrochloric acid to one and a few drops of ammonia to the other and 10 cc of
amyl alcohol to both. Agitate without shaking, allow to settle and drain off alcohol
from both.

(1) Alcohol from a^d solution. — The amyl alcohol is colored red. On addition of
ammonia (dilute) the color becomes green and passes into the water solution, chang-

« Report on processes in use at the municipal laboratory, by Doctor Muter, analyst,
1885.

'>Blyth, Foods, etc., 5th ed., 1903.

cj)r. M. Mansfield, Zts. Nahr. Genussm., 1897, 55.

9251— No. 25—05 3

18

ing soon to brown. The liquid is red, and after addition of ammonia (dilute) changes
to violet blue.

(2) Alcohol from ammonia solution. — Amyl alcohol uncolored. On adding water
and a few drops of hydrochloric acid no color should develop. The liquid is brown
and becomes red on addition of hydrochloric acid.

If the wine gives these reactions, then no coal-tar colors are present.

Cazeneuve.s test. «

For the detection of coal-tar dyes containing the sulpho-group (acid fuchsin, etc. ),
azo colors, Bordeaux red, ponceaus, congo, etc., 0.2 gram of mercuric oxid is added
to 10 cc of wine in a test glass and shaken vigorously for about half a minute, heated
to boiling, and passed through a double filter paper. If the coal-tar colors are present,
the filtrate will be colored red. Wines containing a large amount of tannin some-
times give a light-gray color. Red oxid of mercury can not be used for this purpose.
Some very dark genuine red wines ^ (from .TrolHnger and Portuguese grapes) will
give a red filtrate under these conditions.

In most natural red wines, however, under these conditions the red color is
destroyed.

Falieres- Bitter test. ^'

One hundred cc of wine are made alkaline with 5 cc of ammonia and shaken vig-
orously with 30 cc of ether in a suitable retainer. With a pipette remove 25 cc of the
ethereal layer (filtration is not allowable as the filter paper retains fuchsin) and
evaporate in a white porcelain dish with addition of acetic acid and a strand of white
wool. After evaporation of the ether the wool will be dyed ^ if coal-tar colors are
present and remain white in the absence of such colors.

c. Examination for Foreign \' egetable Colors.

No reliable method can at present be giv en for the detection of the
presence of added vegetable colors in general, and recourse must there-
fore be had to the special tests for vegetable colors given below. The
presence of vegetable colors may be assumed if, after proving the
absence of coal-tar colors, the wine fails to come up to the tests for
pure wines, as given under this heading. In the absence of coal-tar
colors, and when by the preceding examination the presence of foreign
vegetable colors is indicated, the following procedure will be found
useful for indications of the character of the coloring matter present,
but in any case the presence and identity of the indicated color should
be proved by confirmator}^ tests to be found in an}^ of the text-books.

Evaporate a sufficient quantity of the wine, depending upon the amount of color-
ing matter present, to small bulk, then make slightly acid with acetic acid, insert a
piece of wool previously mordanted with tin, and evaporate to dryness in a porcelain
dish. If the wool is dyed, remove it and wash thoroughly with water, note the color
it is dyed, and examine portions of the fiber according to the following table:

«Compt. rend., 1886, 102, b2.
ftBujard and Baier, Hilfsbuch., p. 295.
<^ Rottger, Lehrbuch der Nahrungs-Chemie, 1903, p. 478.

d Fuchsin will be indicated by disappearance of the color on treating the wool
with ammonia.

19

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20

B. SEPARATION AND IDENTIFICATION OF THE COAI-TAR COLORS,
a. Method of Sostegni and Carpentieri.

Zts. anal. Chem., 1896, .3.5, 397; U. S. Dept. Agr., Div. of Chem., Bui. 46, Rev., p.
68; Bui 65, p. Ill (Tolman).

b. Arata's Method.

Zts. anal. Chem., 1889, £8, 639; U. 8. Dept. Agr., Div. of Chem., Bui. 65, p. 112
(Tolman).

It must be observed that certain natural coloring matters dye wool in the f-econd
bath, i. e., orchil, cudbear, etc. See Tolman, J. Amer. Chem. Soc., 1905, .i7, 25.

c. Wolff-Winterthur Method.

This is an application of the method of Cazeneuve (already described)
for the separation of the coloring matters into groups. Proceed as
follows:

Ten cc of wine are shaken with a cold saturated solution of mercuric chlorid, and
after the addition of 10 drops of potassium hydrate (sp. gr. 1.27) and again shakings
is passed through a dry filter paper.

(IJ Faint yellow filtrate: Add acetic acid to acid reaction; the filtrate becomes
rose colored. Acid fuchsin.

(2) Filtrate; yellow red, rose, red-violet. Acidify with hydrochloric acid ; (a) the
color remains unchanged or only rose colored: Oxyazo colors, as Bordeaux, pon-
ceau, etc.; (6) the color changes from yellow-red to blue-red or blue-violet: Amido-
azo colors, as Congo, benzopurpurin, methyl orange, etc. Excess of alkali brings
back the original colors.

d. Detection of Coal-Tar Colors by Extraction with Solvents. '

Paris municipal laboratory method.

Girard and Dupre, Anal, de matieres, etc., p. 167; U. S. Dept. Agr., Div. of Chem.,
Bui. 65, p. 113 (Tolman).

As the solubility of the numerous coal-tar colors in amyl alcohol from alkaline and
acid solution has not as yet been satisfactorily tabulated, complete reliance can not
be placed on the use of amyl alcohol as the sole solvent for all dyes; hence the writer
suggests the successive extraction of the solution both in acid and alkaline condition
with such solvents as ether, acetic ether, acetone, and benzol, in addition to the amyl
alcohol, combining the alkaline extracts and the acid extracts, and evaporating
each of the combined extracts separately to dryness, after washing and filtering, in
the presence of a piece of wool. The basic and acid colors will then be dyed on
separate pieces of wool and can be further examined. In either of the above methods
the dyed wool should be further examined for the identity of the coal-tar color or
colors. This may be done directly on the dyed fiber « to a certain extent, or by dis-
solving out the dye and applying reagents to the extracted dye.

To remove the color wash the wool with dilute tartaric acid and then with water
and dry between filter paper. Saturate the wool with strong sulphuric acid and
press out the color with a glass rod after from five to ten minutes and dilute with
10 cc of water. Remove the wool, make solution alkaline with ammonia, and when
cold extract with 5 to 10 cc of amyl alcohol or other suitable solvent. Separate the

«Lehne and Rusterholze, J. Soc. Chem. Ind., U, 72; Analyst, 1899, ^4, 41.

21

solvent, evaporate to dryness, and examine the color residue by the schemes given
in the following references, consulting the tables of Schultz and Julius. «

Witt, Analyst, ii. 111.

Allen, Com. Org. Anal., ^, (1), 399-420.

Weingartner, J. Soc. Dyers, S, 67.

Dommergue, Zts. anal. Chem., 1887, 26, 100; J. Soc. Chem. Ind., <9, 216.

Girard, Zts. anal. Chem., 1888, 27, 232.

Dupre, Zts. anal. Chem,, 1890, 29, 369.

Girard and Pabst, Compt. rend., 101, 156.

Sorby, Proc. Royal Soc. No. 92, 1867.

Schoop, J. Soc. Dyers, 2, 7.

Stein, Dingl. Polyt. J., 210, 245.

Goppelsroeder, J. Soc. Dyers, ^,5.

Fol, J. Chem. Soc, 28, 193. . ,

Hummel and Lepetit, J. Soc. Dyers, 4, 133.

Leach, Food Inspection and Analysis, New York, 1904. A table including about 50
selected coloring matters which are adapted for and have been found in foods by
various analysts, as listed in State and Government reports, as well as in laws of
various countries dealing with food colors.

Most colors may be conveniently narrowed down to groups and classes by the
scheme devised bv Rota, given in Provisional Methods of Food Analysis.*

e. Special Tests for Coal-Tar Colors.
1. Determinatum of add magenta — Girard' s method.

Girard and Dupr^, Analyse des matieres alimentaires, etc., p. 169; Winton, Conn.
Agr. Expt. Sta. Rept., 1899 (2), 132; Tolman, U. S. Dept. Agr., Div. of Chem., Bui.
65, p. 114.

2. Test for Martins yellow or naphthalene yellow.
Tolman, loco cii.

3. Test for naphthol colors. ^

Fifty cc of wine are acidified with a few drops of hydrochloric acid and wool yarn
placed in the liquid. Boil one-rourth hour. Wash the wool with water and then
boil in fresh water with a few drops of hydrochloric acid for another one-fourth
hour. Wash the wool thoroughly with water and warm with fresh water containing
a few drops of ammonia to dissolve the dye. The solution becomes red. Acidify
the ammoniacal solution with hydrochloric acid and dye another piece of wool.
Examine the dyed wool for identity of dye.

4. Test for Bordeaux red.^

Casali found that the artificial coloring of Italian wines was a very general' prac-
tice, those from the central provinces being chiefly colored with a " Vinoline" red
and those from the south with Bordeaux red (azo-naphthyl-naphthol sul phonic acid).
Treat 50-100 cc of wine with 10-20 per cent of a 10 per cent solution of barium chlorid
and sufficient potassium bisulphate solution to precipitate the barium introduced.
When the precipitate has subsided, decant the supernatant liquid, add 3-6 cc of
hydrochloric acid and sufficient water to restore to its original volume, and boil for
five to ten minutes with a little fat-free wool. In the presence of Bordeaux red the
wool is dyed a bright red color, which does not change on adding ammonia.

« Tabellarische tJbersicht der kiinstlichen organischen Farbstoffe, 4th ed., Berlin,
1902; revised 2d ed. in English, by A. G. Green.

*U. S. Dept. Agr., Bureau of Chemistry, Bui.. 65, p. 115.
<^ Fresenius, Anleitung zur chem. Analyse des Weines, p. 92.
dSUz. Speriment. Agrar. Ital., 1900, 33, (2), 183-189.

22

a SPECIAL TESTS FOR VEGETABLE COLORS

A great many tests for vegetable colors are given, depending largely
on color reactions with different reagents, but these must be used with
very great discrimination, as they depend very largely on a fine judg-
ment of shades of colors, which manj^ e^^es are not able to distinguish.

A great deal of work has been done on detection of vegetable colors,"
but only in a very few cases are the reactions specific enough to be
decisive.

a. Detection of Caramel — Amthor Test,

U. S. Dept. Agr., Div. of Chem., Bui. 65, p. 120; Modification, Bui. 90, p. 226; Zts.
anal. Chem., 1885, U, 30.

6. Detection of Turmeric.

U. S. Dept. Agr., Div. of Chem., Bui. 51, p. 131; Bui. 65, p. 120.

c. Test for Cherry Juice. &

Windisch found that all cherries examined by him contained hydrocyanic acid, as
did also the fermented juice with or without the stones. From this fact he proposes
the following test:

Distill 20-30 cc of the liquid until 2 cc have been collected, and to this distillate
add a drop of guaiacum tincture, together with a drop of copper sulphate solution.
A blue color indicates hydrocyanic acid. The color is fugitive, and if very faint may
be intensified by shaking out with chloroform in which it is soluble. Unfortunately,
however, a negative test does not prove the absence of cherry juice.

d. Kermese ^ {Phytolacca).

Add lead acetate, kermese gives red- violet precipitate; add barium hydrate, ker-
mese gives blue- violet flocks.

II. Brandy, Rum, Liqueurs, Vinegar, etc.
GENERAL DISCUSSION.

Coal-tar colors may be examined for in the usual way as under
wines, after previously boiling out excess of alcohol and filtering off
any .coloring matter precipitated. The color of brand}^ may be due to
the presence of caramel or a deepening of the tint by coloring matter
due to the cask. Arrack is nearly colorless, but ma}" have a slight
tinge of yellow or brown due to long storing in casks. Liqueurs are
often brightly colored by vegetable coloring matters such as chloro-
phyll, turmeric, cochineal, etc. Absinthe is yellowish-green in color,

aGirard and Dupre, Analyse des matieres alimentaires, etc., 580-581, also 169; A.
W. Blythe, Foods, Their Composition and Analysis, pp. 91-109; Allen, Commercial
Organic Analyses, ^, (1); E. Brucher, Falsification des substances alimentaires, p. 162;
W. Lenz, Zts. anal. Chem., 1885, 24, 285.

&Zts. Nahr. Genussm., 1901, 817.

cBujard and Baier, Hilfsbuch, etc., p. 296.

23

due to chlorophyll added for this purpose in the form of juice from
spinach, parsley, etc. The following colors may be looked for:

Cochineal, saffran, safflor, curcuma, indigo (soluble), litmus, sap-blue, caramel,
licorice root, and coal-tar colors (alizarines, Magdala red, primrose, etc.).

Doctor Mansfield « proposes to treat spirits and similar liquid in the
following- way when they contain red coloring matter insokible in water:

Treat with water and a drop of 5 per cent sodium hydroxid.
Solution contains the alizarine colors.
Residue: Heat with 70 per cent alcohol.
If soluble and fluorescent add 33| per cent sodium hydroxid

solution.
If fluorescence disappears — Magdala red.
If fluorescence remains — Primrose.

Hubert* states that the color of genuine absinthe
(chlorophyll) is usually derived from Artemesia pontica^
with the addition in some cases of hyssop. Inferior
absinthes contain more or less color derived from arte-
mesia but in addition other coloring principles, such as
that of veronica. For the detection of foreign coloring
matters he recommends the following procedure:

Shake 20 cc of absinthe with several successive portions (5 cc) of
chloroform until no more color is extracted. The extract is evap-
orated and the residue taken up with water. If the solution is color-
less, or has only a faint yellow tint, the absinthe is free from artificial
colors.

/

TEST FOR CARAMEL {CRAMPTON AND SIMONS).

Fifty cc are measured out at a standard (room) temperature, and
evaporated on a water bath nearly to dryness; the residue is washed
into a 50 cc glass-stoppered flask, 25 cc absolute alcohol added, and
the solution, after cooling to the standard temperature, is made up
to the mark with water. After mixing, 25 cc of the solution are
transferred to the separatory apparatus shown in fig. 1 and treated
with 50 cc of ether for half an hour, being shaken at intervals; at the
end of this period, the layers having separated well, the lower layer
is made up with water to the original volume, 25 cc. This is con-
veniently accomplished by connecting the lower end of the apparatus
with a rubber siphoning tube which carries water from an elevated
flask, the inflow of water being regulated by the stopcock of the
apparatus.

The contents of the flask are again shaken, and again allowed to separate (whereby
the volume of the lower layer is slightly increased), and the watery layer is drawn off
through the stopcock for a reading of its color in the tintometer. At the same time
a reading is taken of the 25 cc of the solution which was not subjected to the treat-
ment with ether; from these two readings the amount of color extracted by ether is

«Zts. Nahr. Genussm., 1897, p. 56.

'^Ann. chim. anal., 1901, 409; Analyst, 1902, 55.

<^J. Amer. Chem. Soc, 21, 355; £2, 810.

Fig. 1.— Separa-
tory apparatus
used in test for
caramel.

24

calculated in percentages. The method is based on the fact that caramel is insoluble
in ether and that after the treatment with ether the liquid remaining (if colored)
can be compared colorimetrically with the original spirits. The authors' original
method « for separating caramel by means of fuller's earth may be used as a valuable
supplementary test.

III. Malt Liquors.

NATURAL AND ARTIFICIAL COLORS.

The natural coloring matter of malt liquors is due to the coloring
matter present in the malt and hops used in the preparation of same.
The coloring matter of malt has been examined b}^ Sorb}^ and examined
spectroseopically. It is an orange yellow color which becomes deeper
yellow with ammonia and 50 per cent sulphuric acid. Fermentation
modifies somewhat the characteristics of the pure coloring matter.
Carbonizing and drying at high heat produces, besides the Original
yellow color, a brown color, probabl}^ caramel or similar color.
Lupulin, the coloring matter of hops, is also yellow. The addition of
vegetable extracts for the purpose of furnishing added "bitters" may
produce more or less artiticial brownish mellow shades — i. e., chiretta,
quassia, wormwood, gentian, aloes, exti'actives, etc., containing alka-
loids, giving color reactions with v^arious reagents. The subjoined
table shows the characteristics of some of them, as in testing the resi-
dues of malt liquors for color reactions of added colors and extracting
them with solvents it would be necessar}^ to take into consideration the
influence these alkaloids would produce on such results.

Absynthin. — Easily soluble in alcohol and ether. Potassium hydroxid produces a
brown color, and concentrated sulphuric acid, first a brown color, passing into a
green blue.

Aloin. — Soluble in alcohol. Sulphuric acid (hydrous) first red, then orange. Potas-
sium hydroxid, a purple red. Nitric acid produces chrysamic and picric acids.

Cnicin. — Soluble in ethyl and methyl alcohol. Cold sulphuric acid gives a red vsolu-
tion, becoming violet on adding water and yellow on adding ammonia. Cold
hydrochloric acid (concentrated) gives a green color.

Daphnin. — Soluble in alcohol. Alkalis give a red color, cold iron chlorid solution a
blue color, which, when boiled, gives a yellow precipitate, and nitric acid a red
color.

Gentianin. — Soluble in alcohol. Sulphuric acid (concentrated) gives yellow color.
Nitric acid, dilute, a dark green, which, on addition of water, precipitates green
dinitro- gentianin. Nitric acid (concentrated) produces trinitro gentianin
(yellow).

Quassiin. — Yellow mass when heated. Precipitated by tannic acid. Sulphuric acid
(concentrated) no color.

TESTS FOR COAL-TAR COLORS.

These will seldom be found, and, aside from fuchsin and picric acid (if added for
bitters), need hardly be considered. By evaporating to small bulk and extracting
with 80 per cent alcohol, the coal-tar colors may be examined for in the filtrate as
given under wines.

«J. Amer. Chem. Soc.,.1899, ^i, 356.

25

Picric acid ( Fleck «).— Evaporate down about one-half liter of beer to consistency
of sirup, mix the residue with ten times the amount of absolute alcohol, filter, wash,
and evaporate the alcoholic solution to dryness, treat this residue with water as long
as the water is colored, evaporate down the watery extract to dryness and extract
with ether. The ether will contain picric acid in a state pure enough to weigh, if
not absolutely pure. The ether may be driven off and the picric acid taken up by
chloroform or benzol and crystallized from either solvent.

TESTS FOR VEGETABLE COLORS.

Caramel may be examined for. in general, as directed under wines. In addition,
Schuster recommends agitating the beer with tannin solution. Pure beer will be
decolorized, while the presence of caramel prevents decolorization. Griessmayer
(1881) recommends adding to a beer highly colored twice its weight of ammonium
sulphate crystals and three volumes of strong alcohol, and when agitated, if the beer
be pure, complete decolorization will take place and a deposit will form, either
brown or black if the coloration is due to malt. If colored with caramel the solution
will remain brown and a gray or brownish deposit will be formed.

IV. Canned Vegetables.

Extract with acidified 80 per cent alcohol or extract with immiscible solvents and
proceed as usual. Lendrich ^ states that it is not unusual for dried pease, either in ,
the whole or split condition, to be artificially colored. They are generally treated
with talc to give a polished surface. Colors employed are green or orange-yellows,
and may be detected by shaking with 50 per cent alcohol and decanting the latter
after about five minutes. Natural pease give a colorless solution. The following
table ^ shows the behavior of the coloring matter from some vegetables extracted
with 80 per cent alcohol:

Behavior of coloring matters extracted from vegetables with 80 per cent alcohol.

Vegetable.

Alcoholic ex-
tract.

Sulphuric acid,
concentrated.

Sulphuric acid
+ water.

Hydrochloric
acid, dilute.

Radish Wine red

Tomato Brown-yellow —

Pease . . . ! Yellow-green

Carrot i Yellow

Red beet ! Orange

Red onion Blood red

Brown-yellow
Red-brown . . .
Brown-violet .

Brownish

Brown

Red-yellow...

Yellow onion i Yellowish Red-yellow . . .

Spinach Dark green Brown-yellow

Green pepper.
Red pepper...
Cucumber

Green ,

Red-yellow
Green

Pink-brown
Pink-brown
Pink-brown

Orange

Brown

Yellowish

Brownish

Brown ,

Red-brown pre-
cipitate.

Dirty yellow

Yellow ish-browh
precipitate.

Yellow-green

Brown

Yellow-green

Orange.
Lighter.
Yellow.
Straw yellow.
No change.
Wine red.

No change.
No change.

Yellowish.

Colorless.

Yellow.

Vegetable.

Ammonium hydrox-
id, dilute.

Ammonium hydrox-
id, concentrated.

Lakes.

Radish ..
Tomato..

Pease

Carrot . . .
Red beet.

Red onion ,

Yellow onion.

Spinach

Green pepper.
Red pepper . . .
Cucumber

Blue-red fluorescence.
Brighter

No change

Green-yellow

Dark orange

Brown-yellow

Green-yellow .

Yellow

Green-yellow .

Brighter

Brighter

Green i

Brighter ■ Tin lake, light brown.

No ohflTifi'p f Aluminum lake, greenish.

NO change j^j^^ j^j^^ ^j^y brown.

Yellow

Green-yellow.

{Aluminum lake, golden yel-
low.
Tin lake, yellow-brown.

Brown-yellow

Bright yellow.

Yellow

Green-yellow .

Brighter

Brighter

Lakes, green-yellow.

Tin lake, light brown.
Aluminum lake, yellow.

aCorrespondenz-Bl. Verein. anal. Chem., 5, 77.
h Zts. Nahr. Genussm., 1904, 1.
c Prepared by the writer.

26

V. Fruits, Fruit Juices (nonalcoholic), Preserves, Jam, Marmalade, etc.

Extract with 80 per cent acidified alcohol, or extract the coloring
matter by means of immiscible solvents, and proceed as usual.

RESULTS ON EXTRACTION OF FRUIT COLORS,

The extraction of fruit colors is shown in the following tables, the
first of which was prepared by Truchon and Martin-Claude'^ and the
second by Tolman.^ The fresh fruit juice was very slightly acidified
by hydrochloric acid before extraction. In no case in the dyeing test
was there any danger of mistaking the vegetable color for one of coal-
tar origin where the double-dyeing method was used.

Extraction of frvit colors with amyl alcohol.

Fruit,

Coloration of acid solu-
tion.a

Coloration of ammoniacal
solution.

Addition of a drop of
H2SO4 to dyed fab-
ric.

T,-.-_ Amyl-alcohol
^^^^^- 1 extract.

Juice.

Amyl-alcohol
extract.

Red

Red

Red

Red

Red

Red

White....
Dark red .
Yellow . . .
Yellow...
Yellow...
Yellow...
Yellow...
Yellow...

Yellow

Uncolored..

Rose

Red

Red

Uncolored..
Uncolored..
Red

Uncolored..
Uncolored . .
Uncolored..
Uncolored..
Uncolored..
Uncolored..

Green

Green

Green

Green

Green

Green

Uncolored

Uncolored —

Uncolored

Uncolored

Uncolored....

TTrir>nlorprl

Yellow.

Ripe cherries

Early strawberries

Ripe strawberries

Raspberries

Yellow.
Rose.

Rose (tints silk a rose
red).

Red currants . ...

White currants

Black currants

Peaches

Brown Uncolored

Deep green . Uncolored

Brown j Yellow-red . . .

Brown \ Yellow-red . . .

Brown \ Yellow-red . . .

Brown i Yellow-red . . .

Brown Yfill nw-rpd . . .

Tints silk rose.
Uncolored

Pears

Quinces

Apples

Green gage plums

Brown

Yellow-red . . .

a Acidity of the juice.
Extraction of fruit colors with amyl alcohol and with ether.

Fruit.

Color with

ammonium

hydroxid.

Color ex-
tracted by
ether from
acid solu-
tion.

Color extracted
by amyl-alco-
hol from acid
solution.

Dyeing tests on the juice.

Strawberry

Red raspberry

Blackberry

Cherry f...

Purple

Purple

Blue-purple ..

Purple

Blue-purple ..
Blue-purple . .
Blue-purple . .

None

None

None

None

None

None

None

Deep red .... .
Deep red ..'...

Very deep red.
Red

Color washed out.

All color does not wash out, but does

not dye in the second acid bath.
Dyes purplish red in acid solution,

but does not dye in the second acid

bath.
Dyes purplish red in acid solution,

but does not dye in the second acid

bath.
Dyes purplish red in acid solution,

but does not dye in the second acid

bath.
Dyes purplish red in acid solution,

but does not dye in the second acid

bath.
Dyes purplish red in acid solution,

but does not dye in the second acid

bath.

Blackberry

Wild dewberry

Red

Red

Currant

Red

a J. pharm. chim., 1901, IS, 174.

ftU. S. Dept. Agr., Bureau of Chemistry, Bui. 66, p. 111.

27

It will be seen from these two tables that amyl alcohol, as a rule,
extracts fruit coloring matter from acid solution, while ether does
not. Neither arayl alcohol nor ether extracted any color from the
alkaline solution of the fruit juices.

Desmouliere ^ found that amyl alcohol extracts a yellow color from
macerated apricots in the presence of acid or alkali. The yellow resi-
due with sulphuric acid gives an indigo-blue color changing to brown
violet. This reaction is identical with that for carotin. The color
does net dye silk or wool.

DETECTION OF COCHINEAL.

Girard and Dupr^, Analyse des mati^res alimentaires, etc.^p. 580; U. S. Dept.
Agr., Bureau of Chemistry, Bui. 65, p. 120.

VI. Dairy Products, Fats, Oils, etc.

A. NATURAL AND ARTIFICIAL COLORS IN MILK.

In examining for the presence of added coloring matters it is well to
consider first the nature of the natural coloring in milk and, conse-
quently, in butter. The natural coloring matter of milk is "lacto
chrome," which may be precipitated from milk whey by nitrate of
mercury in bright red orange resin-like masses, softening at 100° C,
freely soluble in water and hot alcohol, separating from the latter on
cooling (Blyth). Cholesterin occurring in milk is soluble in hot alco-
hol, ether, bisulphid of carbon, and chloroform, and gives characteris-
tic color reactions with certain reagents, as follows:

5 parts sulphuric acid and 1 part water, colored carmine red, then violet. — Mole-
schott's test.

1 part sulphuric acid and 1 part chloroform, colored blood red, violet, or purple. —
Salkowsky's test.

The coloring matter of certain plants when eaten by cows imparts
colors to milk, which, though not natural, may be present through
natural means. Such are —

Marsh marigold and saffron, coloring yellow; rhubarb, opuntia, and madder,
coloring red; buckwheat and forgetmenot, coloring blue. Certain bacteria in milk
develop a blue color which turns cherry red on addition of caustic alkali, returning
to blue on addition of acids (Blyth).

Among the artificial coloring matters which may be considered are
the following:

Vegetable colors. — Saffron, rocou, alkanet, carrot juice (carotin), aspergeoire berries,
marigold and carthamus flowers, chelidoine juice, ranunculus, turmeric, annatto, etc.

Coal-tar colors. — Spirit yellow R, nitrosamine red, aurantia, phosphin, Martins
yellow, picric acid. Mikado yellow, Mikado gold yellow, naphthol yellow S, naphthol
yellow RS, victoria yellow, coralline yellow, acid yellow, methyl orange, orange IV
and similar azo colors, amidoazobenzol, anilin yellow (amidoazobenzol hydrochlorid),
butter yellow (benzinazodimethyl anilin), diazobenzol, etc.

«Ann. chim. anal., 1902, 7, 323,

28

B. BUTTER, FATS, AND OILS {FRESH).

Coal-tar colors will be present with few exceptions in the form of
nonsulfonated bases and will be indicated by the following tests:

«. BUJAKD AND BaIEK TeST.«

Two to 3 grams of fat are dissolved in 5 cc of ether and shaken with 5 cc of concen-
trated hydrochloric acid (1.125). If coal-tar colors are present the solution will be
colored decidedly red. Precaution: "Butter yellow^" does not color hydrochloric
acid (1.19), or does so only slightly. The acid solution may then be used for double
dyeing a piece of wool, as described under " Wines," and the wool or the extracted
dye further examined.

h. Vandriken Test.&

J. Vandriken states that pure butter is completely decolorized by
amyl nitrite. Proceed as follows:

1. Amyl nitrite (acid). — To 2 cc of filtered butter add an equal volume of ether in
a test tube. To this add 6 to 10 drops of amyl nitrite, and shake. Pure butter is
decolorized at once. If unfiltered butter is used, more reagent must be added, and
usually slightly warmed.

2. Nitrous ether. — To 2 cc of filtered butter add 2 cc of ether and 25 to 30 drops of
nitrous ether and shake vigorously. The decolorization takes place more slowly
than with amyl nitrite. Carotin is not decolorized; saffron, only slighly altered;
curcuma, not decolorized; orlean, decolorized; annotto, not decolorized.

c. Leeds Method, c

One hundred grams of butter should be dissolved in a tapped separator in 300 cc of
petroleum ether of about 0. 638 sp. gr. The water, etc. , is tapped off, and the ethereal
solution of the fat and coloring matters washed several times by agitation with water.
The ethereal solution, poured off from the stearin which may have separated on
standing, is then shaken with 50 cc of N/ 10 caustic potash solution, w^hich is sufficient
to effect the solution of all coloring matter capable of being dissolved by dilute
alkali. f' The alkaline solution is separated from the ethereal layer and very cau-
tiously treated with dilute hydrochloric acid until faintly acid to litmus. The precipi-
tate, consisting of coloring matter mixed with a little fatty acid, is filtered off and
washed with cold water. If desired it may be weighed. The following table shows the
reactions of the coloring matters, isolated in the above manner, when two or three
drops of their alcoholic solutions are treated with an equal measure of the reagents
(acids) mentioned,

« Hilfsbuch fiir Nahrungsmittelchemiker, 1900, 144.
6 Ann. Pharm., 1901 (7), 110; Chem. Ztg. Rep., 1901, 106.
c Analyst, 12, 150; Allen, 5 (1), 355.

d A pale yellow color remaining in the petroleum ether is due only to the natural
coloring matter of the butter.

29

Reactions of coloring matters according to Leeds method.

Coloring matter.

Annatto

Annatto, with de-
colorized butter.

Turmeric

Turmeric, with de-
colorized butter,
Saffron

Saffron, with de-
colorized butter,

Carrot

Carrot, with decol

orized butter.
Marigold

Safflower

Anilin yellow —
Martius yellow .

Victoria yellow

Reaction with—

Concentrated sul-
phuric acid.

Indigo blue,
changing to vi-
olet.

Blue, becoming

f:reen and slow-
y changing to
violet.
Rose violet

Violet, changing
to purple.

Violet to cobalt
blue, changing
to reddish
brown.

Dark blue, chang-
ing to reddish
brown.

Amber brown —

Reddish brown

to purple.
Dark olive green,

not changing.

Light brown.

Yellow

Pale yellow

Partially decolor-
ized.

Concentrated
nitric acid.

Blue, becoming
colorless on
standing.

Blue, becoming
green and col-
orless.

Violet

Sulphuric and
nitric acids.

Blue, becoming col-
orless on stand-
ing.

Decolorized

Concentrated hydro-
chloric acid.

Violet.

Violet to red-vio-
let.

Light blue,]
changing to
light reddish
brown.

Blue, changing t
to green and '
brown.

Decolorized

Yellow and decol-
orized.

Blue, instantly
changing to
dirty yellow-
green.

Partially decolor-
ized.

Yellow

Yellow, red pre-
cipitate, ma-
genta at mar-
gin.

Partially decolor-
ized.

Violet to red-violet

Light blue, chang-
ing to light red-
dish brown.

Blue, rapidly
changing to pur-
ple.

Decolorized with
red fumes and
odor of burnt su-
gar.

Yellow and decol-
orized.

Green

Decolorized

Yellow

Yellow

Partially decolor-
ized.

No change, or mere-
ly dirty yellow or
brown color.

No change, or only
dirty yellow.

Violet, becoming
yellow on evapo-
ration of acid.

Very fine violet.

Yellow, changing to
dirty yellow.

Yellow, becoming
dirty yellow.

No change.

Slightly brown.

Green, to yellow-
green.

No change.

Yellow.

Yellow precipitate,
which deflagrates
when treated with
ammonium hy-
droxid and heated.

Yellow, color returns
on neutralizing
with ammonium
hydroxid.

d. Special Tests (Saffron, Turmeric, Marigold, Annatto).

1. Martin test. «

Add gradually 2 parts carbon bisulphid, with gentle agitation, to 15 parts of alcohol
or wood spirits. Five grams of the butter to be tested, which need not be previously
clarified, is shaken with 25 cc of this solution. On standing for a few minutes, the
mixture separates into two layers, the lower of which is a solution of the fat in carbon
disulphid while the upper alcoholic stratum will be yellow if any artificial coloring
matter be present. If the butter be but slightly colored a larger amount should be
employed. The alcoholic stratum will give a greenish coloration with nitric acid,
and a red with hydrochloric acid and sugar if saffron be present. A brownish color
with ammonia indicates turmeric, and a blackish coloration with silver nitrate mari-
gold. If the alcoholic solution be evaporated to dryness, and the residue treated
with concentrated sulphuric acid, annatto will be indicated by a greenish blue, and
saffron by a blue, coloration. On adding a few drops of boric-acid solution and again
evaporating turmeric will be indicated by a bright brownish-red coloration, changed
to blue, green, or violet by caustic alkalies.

2. Carotin test {Moore) . &

When a butter colored with carotin is dissolved in carbon disulphid and shaken
with alcohol, as prescribed by Martin, the alcohol remains colorless, while the lower
layer is deeply colored, but on adding a drop of a dilute solution of ferric chlorid and

a Analyst, 12, 70; Allen, S, (1), 354.

ft Analyst, 12, 163.

30

again shaking a gradual change is observed, and the alcoholic layer becomes dis-
tinctly yellow and the bisulphid solution of the fats quite colorless, or retaining only
the pale yellow color due to the natural coloring matter of the butter.

3. Test for saffron, curcuma, carotin, rocou {Chenallier and Baudrimont).^'

Treat with warm alcohol and test extract with subacetate of lead, an orange color
indicates the presence of saffron; treat with alkali and a brown color indicates cur-
cuma, and a green color, carotin; treat with concentrated sulphuric acid and a red-
brown color followed by blue indicates rocou.

4. Test for egg yellow.

Three hundred grams of fat are melted at 50° C, 150 cc of a 2 per cent solution of
sodium chlorid added, and the mixture kept at 50° C. for two hours. The mixture
is then well cooled and the aqueous solution separated and repeatedly passed through
a filter until as clear as possible. A perfectly clear and colorless filtrate, how^ever,
indicates the absence of egg yolk. On adding an equal bulk of concentrated hydro-
chloric acid to a filtrate which is persistently turbid, a clear solution is obtained
again, becoming turbid on heating. Should egg yolk be present a further test is to
acidify 10 cc of the salt solution with 1 cc of a 1 per cent sulphuric-acid solution,
heat to boiling for a short time, cool, and shake with 2 cc of ether. The latter dis-
solves the coloring matters of the egg yolk should any be present, and the ethereal
layer is colored faint yellow\ Consult an extended article on this subject by Dr. G,
Fendler. &

a BUTTER, FATS, ETC. {RANCID).

If butter has become rancid the acid water from the petroleum ether extract as
obtained when testing fresh butter should be examined for reduced coal-tar dyes by
the method given below under milk (sour).

D. MILK {FRESH).

a. Leach's Method, c

The author uses the generic name of "anilin orange" as applied to all the coal-
tar dyes of the classes of diazo compounds of anilin, thus including single or mixed
dyes under this head. About 150 cc of the milk are curdled by the aid of heat and
acetic acid, preferably in a porcelain casserole over a Bunsen flame. By the aid of a
stirring rod the curd can nearly always be gathered into one mass, which is much the
easiest method of separation, the whey being simply poured off. If, however, the
curd is too finely divided in the whey the separation is effected by straining through
a sieve or colander. All of the annatto or of the anilin orange present in the milk
treated would be found in the curd and part of the caramel. The curd pressed free
from adhering liquid is picked apart, if necessary, and shaken with ether in a corked
flask, in which it is allow^ed to soak for several hours or until all the fat has been
extracted, and with it the annatto. If the milk is uncolored or has been colored
with annatto, on pouring off the ether the curd should be left perfectly white. If, on
the other hand, anilin orange or caramel has been used, after pouring off the ether
the curd will be colored more or less deeply, depending on the amount of color
employed. In other words, of the three colors, annatto, caramel, and anilin orange,
the annatto only is extracted by the ether. If caramel has been used, the curd will
have a brown color at this stage; if anilin orange, the color of the curd will be a
more or less bright orange.

« Diet, des alterations et falsification des substances alimentaires, etc., 7th ed., p. 236.
&Zts. Nahr. Genussm., 1903, 971.
cj. Chem. Soc, 1900, 207.

31

The ether extract, containing the fat and the annatto, if present, is evaporated on
the water bath, the residue is made alkaline with sodium hydroxid and poured upon
a small, wet filter, which will hold back the fat and, as the filtrate passes through,
will allow the annatto, if present, to permeate the pores of the filter. On washing
off the fat gently under the water tap all the annatto of the milk used for the test
will be found to have been concentrated on the filter, giving it an orange color, tol-
erably permanent and varying in depth with the amount of annatto present. The
confirmatory test for annatto with stannous chlorid may afterwards be applied to the
colored filter, producing the characteristic pink color.

The fat-free curd, if colored after the ether has been poured off, is examined fur-
ther for caramel or analin orange by placing a portion of the curd in a test tube and
shaking vigorously with concentrated hydrochloric acid. If the color is caramel, the
acid solution of the colored curd will gradually turn a deep blue on shaking, as
would also the white fat-free curd of an uncolored milk, the blue coloration being
formed in a few minutes if the fat has been thoroughly extracted from the curd;
indeed, it seems to be absolutely essential for the prompt formation of the blue color
in the ae\d solution that the curd be free from fat. Gentle heat will hasten the
reaction. It should be noted that it is only when the blue coloration of the acid
occurs in connection with a colored curd that caramel is to be suspected, and if
much caramel be present the coloration of the acid solution will be a brownish blue.
If the above treatment indicates caramel, it would be well to confirm by any of the
usual tests on a fresh sample of the milk. If the milk has been colored with anilin
orange, the colored curd, on applying the strong hydrochloric acid in the test tube,
will immediately turn pink. In the case of caramel, the color of the curd itself
remains unchanged, the solution only turning blue, and that gradually; on the con-
trary with the anilin orange the curd itself takes the pink color the moment the
acid touches it. If a large amount of the anilin orange has been used in the milk,
the curd will sometimes show the pink coloration when hydrochloric acid is applied
directly to it, before treatment with ether, but the color reaction with the fat-free
curd is very delicate and unmistakable.

Summary of procedure.

Curdle 150 cc of milk in casserole with heat and acetic acid. Gather curd into one
mass. Pour off whey, or strain if curd is finely divided. Macerate curd with ether
in a corked flask. Pour off ether.
Ether extract:

Evaporate off ether; treat residue with sodium hydroxid and pour on wetted
filter. After solution has passed through wash off fat and dry filter,
which, if colored orange, indicates presence of annatto. (Confirm by
stannous chlorid. )
Collected curd :

(1) If colorless, indicates presence of no foreign color other than in ether extract.

(2) If orange or brownish, indicates presence of anilin orange or caramel.

Shake curd in test tube with concentrated hydrochloric acid.

(a) If solution gradually turns blue, indicates caramel. (Confirm by

testing for caramel in whey of original milk. )

(b) If orange curd immediately turns pink, indicates anilin orange.

To differentiate the azo dyes included under the term ''anilin orange," dye a
piece of wool in the acid solution, extract the dye from the wool with ammonium
hydroxid, and apply the tests as indicated in the table on page 34, headed "Coal-
tar colors." «

« Note bv the writer.

32

b. Caramel Test« (Modification by Blyth of Leach's Test&).

Use a milk known to be free from caramel as a control. Take 50 cc of the sus-
pected milk and the same quantity of the control, coagulate each by the addition of
acetic acid, strain off the whey from the curd by means of a piece of fine muslin.
Carefully compare the colors of the whey from both samples. Place the curds in
two white porcelain basins and just cover them with strong hydrochloric acid.
Compare the colors after they have stood several hours. Caramel will be indicated
by a brownish- violet color; but the pure curd will also develop a similar color after
standing for a long time, so that great care must be exercised in coming to a conclu-
sion. The use of the control milk greatly increases the delicacy of the test.

E. MILK {SOUR), BLYTH' S METHOD.c

The color of the milk should be carefully noted, as some dyes, such as anilin yel-
low and acid yellow, impart a faint pink color to the curd of sour milk. Butter yel-
low, on the other hand, rises with the fat, which it at first colors yellow, but
afterwards becomes colorless. Annatto imparts a characteristic color to the curd
and, like saffron and turmeric, does not become colorless in decomposed milk. Car-
amel colors both the curd and the whey. If it be desired to make a comparison
between the milk when fresh and after partial decomposition, two portions should
be incubated, one containing sufficient formalin to prevent any decomposition.

The following general method will be found most convenient: Take 50 cc or more
of the milk and render it just alkaline to delicate litmus paper, evaporate to a paste,
and thoroughly extract the fat with ether. Although turmeric, annatto, and such
dyes as anilin yellow are all somewhat soluble in ether from an alkaline solution,
yet in the presence of casein such small quantities are dissolved that they may be dis-
regarded. (Phosphin is much more soluble in ether and should be looked for both
in the ether and alcohol extract. )

Evaporate the ethereal solution to dryness, shake up the fat with a small quantity
of hot distilled water in a small separating funnel, separate the water from the fat,
and evaporate to dryness on the water bath in a small flat porcelain dish; carefully
note the color of the residue. (See following table. ) Pure milk will give no colored
residue. Next thoroughly exhaust the fat-free milk residue with absolute alcohol,
pass the extract through a small filter, and evaporate to dryliess in three or four
small flat porcelain dishes; if unreduced artificial coloring matter be present the
residue will be colored orange, yellow, or brown. Wash one of the residues into a
test tube with a small quantity of water made acid with sulphuric acid. The sul-
phonated azo dyes will be at once indicated by the color of the solution. Shake the
solution with ether. This will divide the coloring matters into two groups as in the
table; the natural coloring matters and the non sulphonated acid coal-tar dyes — i. e.,
the dyes precipitated by Weingartner' s tannin reagent — being soluble in ether, while
the basic dyes and the sulphonated dyes are insoluble in ether. The ordinary tests
may then be applied to the remaining portions of the dyes.

a Analyst, 1902, p. 151.

& Blyth finds that caramel may be formed from the milk sugar if any evaporation
process be used in testing for caramel,
c Analyst, 1902, p. 146.

33

a. Alcohol Extract, Colored Orange, Yellow, or Brown.

Take up a portion of the residue with dilute sulphuric acid and shake with ether.

(1) Ether dissolves some of the coloring matter:

Natural coloring matter —

Annatto.

Turmeric.

Saffron.

Carotin.
Nonsulphonated acid coal-tar colors, such

Anilin yellow.

Butter yellow.

Victoria yellow.

Martins yellow.

(2) Ether does not dissolve the coloring matter:

Basic coal-tar colors, such as —

Phosphin.
Sulphonated coal-tar colors, such as —

Acid yellow.

Methyl orange. ,

Orange IV.

h. Water Extract from the Fat.
Note the color and apply various reagents to the dry residue.

Color of
residue.

Probable origi-
nal coloring
matter.

Add drop of
ferric chlorid.

To the ferric
chlorid add
strong sul-
phuric acid.

Other reactions.

Brown.
Brown.

Brown

Yellow ....
Yellow ....
Rose red...
Brown red.
Yellow ....

Acid yellow . .
Butter yellow.

Anilin

low.
Martins

low.
Victoria

low.
Methyl or

ange.
Orange IV . .

yel-
yel-
yel-

Dark green . . .

Dark - blue
green. ,

Yellow
Red ...

Red

Fugitive scar-
let.
Green

Yellow, green
on dilution.

Yellow, green
on dilution.

Yellow

Yellow
Yellow

Yellow

Scarlet, green
on dilution.

Unreduced dyes, soluble in ether from alkaline solution

To slightly acid solution of the coloring
matter add a few drops of hydrogen
sulphid solution, then ferric chlorid,
heat— magenta color.

Strong sulphuric or hydrochloric acid
gives delicate violet.

Strong hydrochloric acid gives a beauti-
ful rose-red color.

Same as Martins yellow.

Treat as with butter yellow; the solution
becomes a beautiful blue.

Treat as butter yellow; the solution be-
comes a dirty violet.

34

F. CHEESE.

Extract the dried cheese with hot alcohol, evaporate extract, and test residue for
acid coal-tar colors and vegetable colors soluble in alcohol. Extract the cheese resi-
due with petroleum ether for nonsulphonated coal-tar colors and vegetable colors
insoluble in alcohol, and proceed as with butter and milk.

Coal-tar colors.

Colors.

Nitrosamin red

Spirit yellow R.

Aurantia

Phosphin

Picric acid

Martius yellow...

Mikado yellow...

Mikado gold yel-
low 2G.

Naphthol yellow
S.

Naphthol yellow
RS.

Victoria yellow . .

Coralline yellow .

Acid yellow...
Diazo-benzene

Amido-azo -ben-
zene.
Butter yellow

Anilin yellow.

Methyl orange . . .
Orange IV

Color on wool.

Orange

Unmordanted
cotton, yellow.

Greenish yellow
Golden yellow..! Yellow

Sulphuric acid
concentrated.

Brown.

Yellow p r e -
cipitate.

Red yellow,
green fluo-
rescence.

Cotton, yellow
to orange.
Cotton, yellow..

Yellow

Yellow
Orange

Yellow

Yellow
Yellow

Blue

Red to orange

Yellow

Pale yellow...
Light yellow .

Yellow

Brown yellow

Yellow brown

Yellow

Brown

Brown.
Violet .

Water added.

Red precipitate.

Yellow precipi-
tate.
Red vellow

Yellow precipi-
tate.

Brown precipi-
tate.
Yellow brown.

No precipitate .

No precipitate .

No precipitate .

Yellow precipi-
tate.
Orange

Decomposed...

Red ....'.

Red

Magenta red . .

Violet precipi-
tate.

Other reactions.

Dilute hydrochloric acid pre-
cipitates para-nitrophenyl-
nitrosamin.

Hydrochloric acid, red crys-
tals.

Hydrochloric acid, hexanitro-
diphenylamin.

Melting point, 122.5°; boiled
with potassium cyanid gives
brown coloration.

Hydrochloric acid precipi-
tates dmitro-naphthol , melt-
ing point of 138°.

Hydrochloric acid, dark-
brown precipitate.

Hydrochloric acid, brown to
yellow soluble precipitate.

Hydrochloric acid, no pre-
cipitate.

Hydrochloric acid, clear yel-
low.

Hydrochloric acid precipi-
tates, white dinitrocresol.

Hydrochloric acid, orange.

With acids forms colorless
salts, turning brown; explo-
sive.

Yellow crystals, melting point
127.5°.

Yellow precipitate, melting
point 115°.

Boiled with water precipitates
yellow base, melting point
127.5°.

Hydrochloric acid, magenta
red.

Hydrochloric acid, violet pre-
cipitate. Crystallizes from
boiling water in orange
spangles.

35

VII. Flesh Foods.
NORMAL AND ABNORMAL COLORS.

Among the artificial coloring matters which maj^ be considered are:

Vegetable colors. — Carmine, cochineal, logwood, archil, caramel, burnt chicory,
liquorice, elderberry juices, etc.

Coal-tar colors. — Fuchsin, magenta red, diamond red, safranin, fluoresceine,
eosines, ponceaus, Bordeaux reds, picric acid, benzopurpurin, and various mixtures
of several dyes.

Vegetable colors are rarely used for flesh foods (Spaeth).

The normal red color of flesh is due to the presence of several col-
oring matters. Hemoglobin is the dark-purple coloring matter of
venous blood. Oxj^ hemoglobin is the bright-red coloring matter of
arterial blood. Lipochrome is the rosy-red coloring matter present in
the muscular tissue of fishes. Healthy oysters may exhibit a green
color, due to a pigment termed marennin. Normal horseflesh may
exhibit a play of iridescent color.

Various abnormal colors not due to added coloring matter may be:

Yellow, due to food or to biliary compounds in disease.

Brown, due to greenish-brown pigments.

Dark purple, due to the animal having suffered from acute fevers, rinderpest, or
tuberculosis, or to insufficient bleeding after killing.

Dark red, due to drowning or to suffocation in smoke (carbon dioxid poisoning).

Dark brown, hunted or overdriven.

Scarlet, from carbon monoxid poisoning or arsenic poisoning ( Walley ) .

Diffused redness, from being frozen or to blood poisoning.

Iridescence, from disease of the blood in animals other than the horse.

Green or violet, commencement of putrefaction or diffusion of vegetable coloring
matter through the membranes of the stomach after death ( Walley ) . In diseased
oysters due to green leucocytes.

Various chromogenic bacteria « also produce bright red, blue, green, or violet color-
ations.

The artificial coal-tar* colors used in sausages and meats in general
may be conveniently divided into the following classes:

1. Those which color the meat but not the fat. In this case the surface of the
meat is coated mechanically with some of the color, while the fat remains perfectly
white. These dyes are insoluble in petroleum ether and generally insoluble in ether.

2. Those which color the meat and fat uniformly red. These are only mechanic-
ally distributed and are not in solution, and by malting the mass the fat separates
colorless. These are insoluble in petroleum ether and generally in ether.

3. Those which color the meat and fat a uniform red color, the color being in solu-
tion (soluble form). The separated fat from the melted mass remains red. These
colors are in general soluble in ether and insoluble in petroleum ether.

Three methods ^^ may be used to advantage in the examination of flesh foods, each
one having its advantage, viz:

« Consult C. A. Mitchell, Flesh Foods, 1900, p. 270.

& Juckenack and Sendtner, Zts. Nahr. Genussm., 1899, 181.

<-"See also Polenske — Arb. Kaiserl. Gesund., 1900, 17, 568. Schweissing — Pharm.
Centralb., 27, 441. Reinsch— Zts. offentl. Chem., 1900, 485. Weller and Riegel—
Forschungsb., 1897, 4, 204.

86

BUJARD AND BAIER METHOD a

The finely divided material is extracted repeatedly with 80 per cent alcohol, and
the extract diluted with twice the quantity of water. Allow to stand until cold and
filter, several times if necessary, until filtrate is clear. Place on the white surface
and observe whether the solution is colored; if this be the case, evaporate on water
bath to about 20 cc; allow to cool and filter. Examine the filtrate for coal-tar colors
by methods given under wines.

KLINGER AND BUJARD METHOD,^ MODIFIED BY BREMER. c

Twenty grams of finely minced material are heated for several hours with two vol-
umes of a mixture of equal parts of glycerin and water made faintly acid with tartaric
acid. The yellow solution freed from fat is filtered and the carmine precipitated
with alum and ammonia as a lake. On placing the test tube before the microscope,
the absorption lines of carmine-lake, lying between B and D, may then be identified.
Since the acid solution of the sausage-coloring matter is yellow, while carmine-lake
gives a red solution with acids, the carmine may be present in the sausages in some
form combined with the preservatives insoluble in alcohol. Weller and Eiegel con-
cluded that this method was only reliable when the coloring matter could be precip-
itated from its solution as a lake. Since many vegetable colors, which are soluble in
water but insoluble in alcohol or amyl alcohol can not be precipitated as lakes, this
method may often fail.

SPAETH METHOD d

Heat the finely divided material for some hours on the water bath at 100° C. and
then extract with ether. The fat-free substance is then warmed on the water bath
with a 5 per cent solution of sodium salicylate for one hour. The solution is filtered
and ammonia added to one portion; observe whether a lake separates. As ammonia
may sometimes give red precipitates, consisting of calcium and magnesium phosphates
and possibly aluminum hydroxid carrying down traces of anilin colors mechanically,
the precipitate obtained, if any, must be further examined for carmine. Another
portion of the filtrate is acidified with sulphuric acid and heated with wool free from
fat and examined for coal-tar colors, as under wines. It is not necessary to remove
the precipitated salicylic acid before dyeing the wool.

MICROSCOPIC EXAMINATION [MARPMANN).e

A section of the sausage or other meat, about 1 cm thick, is thoroughly moistened
with 50 per cent alcohol and examined under the microscope. When only
traces of coloring matter are present, the substance is dehydrated in xylol, which is
expelled by means of carbon tetrachlorid, and the mass placed in cedar oil. As
thus prepared it is transparent and coloring matters can readily be recognized.
Fuchsin, magenta red, diamond red, carmine, logwood, and archil stain the cell sub-
stances, while acid anilin colors dye the liquid in the cell. In some instances (e. g.,
with safranin) the coloring matter must be concentrated and wool or animal tissue
placed in the concentrated solution. The finely-divided substance is digested with

oHilfsbuch fiir Nahrungsmittelchemiker, 1900, p. 163.

&Zts. angew. Chem., 1891, p. 515.

c Forschungsberichte, 1897, p-. 45, 216; C. A. Mitchell, Flesh Foods, p. 143.

^Pharm. Centralb., 1897, 38, 884; Zts. Nahr. Genussm., 1901, 1020.

«Zts. angew. Mikros., 1895, p. 12; C. A. Mitchell, Flesh Foods, p. 142.

87

50 per cent alcohol, the liquid (fat-free) evaporated to a few drops, and some undyed
sausage placed in this solution. The muscular fibers and the fat cells are then stained
deeply. The sausages should also be extracted with ammonia water, which is a bet-
ter solvent than alcohol for many of the colors used in flesh dyes. Marpmann
regards with suspicion all sausages which remain colored after being kept for two
hours in 50 per cent alcohol, since normal flesh is decolorized under these conditions.
The following table shows the behavior of different flesh proteids on treatment with
certain anilin colors:

Behavior of flesh proteids treated with anilin colors.

Flesh proteids.

Corallin.

Eosin.

Phloxin.

■

Congo red.

Safranin.

Alhnmin

Bluish-rose

Raspberry red
Raspberry red

Raspberry red
Raspberry red

Orange-yellow,
afterwards de-
colorized.

Orange pre-
cipitate.

Decolorized.

Reddish

Brown

Rose

Yellow.

Alk&line a 1 b u -

Violet-rose . . .
Rose

Reddish

Rose

Yellow.

minate.
Fibrin

Red

Red

Yellow-red.

VIII. Coflfee, Tea, Cocoa, Spices, etc.
COLORING MATTERS CONSIDERED.

Turmeric, caramel, chicory, roasted cereals, azo dyes, indigo, catechu, campechy
wood, humus, kino, graphite, mineral pigments.

FACINGS, a

Unroasted coffee beans contain viridic acid, which is soluble in sulphuric acid
with a crimson color turning bright green on addition of alkalis. Inferior or dam-
aged coffees are not infrequently treated by some process for improving their appear-
ance and giving them the appearance of superior grades. For this purpose mineral
pigments may be used for facing or coloring and azo dyes for brightening. The natu-
ral coloring matter of tea is extracted from the dry leaves by hot alcohol, giving a
yellowish-green solution, turning bright yellow on adding ammonia. Sulphuric acid
(cone.) on the color gives a bright green, remaining green on addition of water.
The artificial colorings of tea will be found usually in the form of facings. They
may be detected by the microscope by examining a portion of the leaf, when the
coloring matter appears as small dots, or by chemical means.

AZO DYES.

Treat with hot strong alcohol, evaporate to dryness, take up with warm water and
filter, or if necessary separate the fat or oil from the water solution by agitation
with a suitable solvent. Examine the water solution for coal-tar colors, as under

INDIGO.

Under the microscope indigo appears of a greenish blue. Its color is not dis-
charged by sodium hydroxid, a distinction from Prussian blue. Indigo forms a deep
blue solution with sulphuric acid. Hyposulphite of soda will dissolve indigo, reduc-
ing it at the same time. This solution may be used to dip a piege of wool in, which
on exposure to the air will turn blue if indigo is present.

«U. S. Dept. Agr., Bureau of Chemistry, Bui. 13, Part 7, Tea, coffee, and cocoa
preparations, pp. 880, 909.

38

CATECHU {HAGERS METHOD). (^

Small quantities of this substance can not be detected with certainty. Boil an
extract of tea (1 gram per 100 cc of water) with an excess of litharge and filter;
the filtrate should be clear. To a portion of the filtrate add a solution of silver
nitrate. In the presence of catechu a yellow flocculent precipitate is formed, which
rapidly becomes dark. Under the same conditions pure tea gives a slight grayish
precipitate of metallic silver. The writer suggests agitating the tea extract with ether,
evaporating the ether extract to dryness after shaking with bone char to decolorize,
and testing the residue with concentrated sulphuric acid for the presence of catechin,
which gives a deep purple coloration. Blyth & states that any amount present to the
extent of 3 per cent or over is shown by precipitating an infusion of the tea with a
slight excess of neutral lead acetate, filtering, and adding a little ferric chlorid
(dilute). If catechu be present there is a bright-green color, and ultimately a pre-
cipitate of a grayish-green color. The same infusion filtered from the lead precipi-
tate gives a copious precipitate with silver nitrate.

CAMPECHY WOOD.c

Eder exhausts 1 gram of tea with 100 cc of boiling water and adds chromate of
potash, which gives a blackish-blue color if the wood is present.

CHICORY.

Chicory can be most readily and certainly identified in mixtures by means of the
microscope. The microscopic appearances of coffee and chicory are shown in Bul-
letin 13.<^ Chemical methods for its detection are given by Wittstein, ^ Franz,/
and Hiepe. Q

SANDERS WOOD IN COCOA. f^

Sometimes added for masking the addition of starch. Two to three grams are
shaken with 10 cc of absolute alcohol. With pure cocoa the alcohol remains colorless
or colored only a slight yellow, and gives a white precipitate with sodium hydroxid
and no reaction with ferric chlorid. The filtered alcohiolic extract from sanders M^ood
or cocoa mixed with the latter is, on the other hand, colored, and gives with dilute
sodium hydroxid an intense violet color. Should the wood have been previously
exhausted this coloration is less pronounced. Ferric chlorid also yields a deep
violet color with the unexhausted wood, but in the case of exhausted wood this
reaction is only to be obtained by allowing a drop of the reagent to run on to the
surface of the alcoholic extract. A violet ring is then formed, which disappears on
shaking. Acetone may replace the alcohol.

TURMERIC IN RHUBARB, i

Anselmier shakes 0.1000 gram of the powder with 20 drops of olive oil for one
minute. One drop of the mixture is then placed on white filter paper, when a
characteristic yellow ring is formed should turmeric be present. The ring given
by rhubarb can not be mistaken for the turmeric ring.

«Pharm. Central-Halle, 1879, 258.
& Blyth, Foods, 1896, p. 423.
c Bujard and Baier, Hilfsbuch, p. 225.

f^U. S. Dept. Agr., Bureau of Chemistry, Bui. 13, Part 7, Tea, coffee, and cocoa
preparations, plates 42, 43, and 45.
^Dingler's polytech. J., ^11, 78.
/Arch. Pharm., (3) <?, 298.
9' Moniteur scientifique, (3) 10, 1339.
^ Zts. offentl. Chem., 1902, 203. (R. & L.)
iChem. Ztg. Rep., 1904, 80.

39

Bell « employs a reagent prepared by dissolving 1 gram of diphenylamin in 20 ce
of 90 per cent alcohol and adding 25 cc pure sulphuric acid. A drop of this solution
is placed on a microscopic slide; a small quantity of the powder under examination
is spread over a cover glass and the latter placed on the slide, which is then examined.
Turmeric develops purple-colored spots throughout the field of vision. This method
is said to detect 1 part turmeric in 1,000 parts of mustard and 1 part in 200 of rhubarb.

PEPPER COLORS.

Sometimes colored with a preparation of sulpho-azo-benzol-y5-naphthol and
barium sulphate (60 per cent). Such a colored powder gives with boiling water a
beautiful red filtrate. ^ According to Mennechet ^ some peppers (those adulterated
with the fruit of Myrsine africana L., and Emhelia ribes Burm. ) give a yellow
extract when lixiviated with ether. If the ether extract be shaken with several
volumes of water and rendered alkaline with ammonia a lilac-red color is produced,
soluble in the water solution, but insoluble in the ether solution. If acidified the
ether becomes colored again and the water solution decolorized.

IX. Starch Preparations (Pastry, Macaroni, Nudeln, etc.).
COLORS CONSIDERED.

Egg yellow, saffron, curcuma, orlean, picric acid, Victoria yellow, Martins yellow,
naphthol yellow, etc.

METHOD FOR COAL-TAR COLORS {REICHELMANN AND LEUSCHER).d

Extract 50 grams of material on water bath with reflux condenser, and 75 cc of
acetone for from forty-five minutes to one hour. Pour off the liquid into another
flask and distill off acetone. Add 30 cc of water to residue in flask, cool and filter
from the fat. The filtrate may be tested for coal-tar dyes by usual methods.
Natural egg color will remain in the fat. In testing for tropseolin in pastry, Brebeck «
has noticed that wheat, oatmeal, and other flours themselves contain a substance
which gives the same violet coloration with sulphuric acid as does tropaeolin and
that it may be mistaken for the latter. Schmitz has also noticed that wheat gives
a violet coloration, but only after some time; and Popp states that the color is
due to the action of the acid on the oil contained in the flour. By removing the
oil from the material by means of ether no reaction is obtained on flours.

X. Confectionery.
COLORS CONSIDERED./

Cochineal and carmine lakes and alumnia lakes of vegetable colors. Carthamic
acid, redwood dyes, cherry and beet juices, Chinese and spinach greens, indigo, litmus,
archil blue, caramel, licorice, curcuma, kermes, alzarin and purpurin, and coal-
tar colors in general. Alkaline buckthorn juice gives a green used for coloring
pistache.

«Pharm. J., 1902, 551.

& Komm. des Arzneibuch, 2, S.

cJ. pharm. chim., 1901, [6] U, 557.

<^Zts. Nahr. Genussm., 1903, p. 175.

^Zts. offentl. Chem., 1902, 397.

/ Colors in Confectionery, the official circular of the National Confectioners' Asso-
ciation of the XJnited States, February, 1899, contains a useful classified list of colors
considered by them harmless or injurious. This list may also be found in Food
Inspection and Analysis, 1904, by Leach.

40

METHODS.

No unvarying method can be used for the examination of confectionery, owing to
the wide range of material that enters into its composition, and much discretion
must be used in making analyses in view of this fact. Portions may be advan-
tageously isolated from each other mechanically, and after being roughly sepa-
rated they are subjected to a preliminary treatment by agitating with warm
water and allowed to stand for from 10 to 12 hours, when the water solution and
insoluble residue are examined separately. According to whether the material is
chiefly nitrogenous (as candied fruits, etc.) or of the carbohydrate class, a different
line of examination should be adopted. In general, the following outline may be
applied to the separated portions:

Digest with warm 20 per cent alcohol and filter.

Residue.

Extract with immiscible solvents for col-
ors not extracted by 20 per cent alcohol.

Residue (if still col-
ored ) :
Treat with oxalic
or tartaric acids
and examine for
color lakes.

Filtrate:
Examine as usual.

Filtrate.

Examine as in whines by means of immis-
cible solvents and dyeing on wool.

After treatment with solvents epcamine for mineral pigments
in the residues.

Bujard and Baier« recommend extracting with alcohol, adding water and pouring
10 per cent hydrochlic acid over the residue and observing the degree of yellow color
produced, an immediate yellow indicating picric acid and a yellow after a short
time indicating (iinitrocresol. If treated wuth metallic zinc for from one to two hours,
picric acid gives a blue color and dinitrocresol a clear blood red.

aHilfsbuch, p. 211.

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