Albert Ernest Leach.

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Chief of Ihe Denver Food and Drug Inspection Laboratory, Bureau of Chemistry, U. S. De-
partment of Agriculture; formerly Chief Analyst of the Massachusetts
Stale Board of Health.



London: CHAPMAN & HALL, Limited.

Copyright, 1904, 1909,



Entered at Stationers' Hall.


'Eltf ■^'cifntific Press
^'cui 11 ink


During the five years that have elapsed since the appearance of
the first edition, much progress has been made in food control work
both in America and in Europe. In the United States the passage of
the national pure food law, perhaps more than any other single factor,
has contributed toward this, and has itself been the direct cause of
ncreased activity on the part of many of the States. New standards
have been adopted, many new methods have been tried out and found
useful, and in some cases old ones have been displaced.

The most important of these changes and improvements have, it is
believed, been embodied in the present edition, and include new material
and modern methods of analysis covering a wide variety of subjects.
Notable among these are meats and meat extracts, flour (including
methods for determining the grade and for the detection of bleaching)
noodles and Italian pastes, paprika, prepared mustard, tea, coffee, cocoa
products (including milk chocolate), ice cream, maple products, honey,
oils (including the Polenske number and Bomer's phytosterol-acetate
test for vegetable oils), distilled liquors, preservatives (notably benzoic
acid), etc,

A separate chapter on the refractometer, its varieties and application
to food analysis has been introduced; also a separate chapter on flavor-:
ing extracts, including the lesser used extracts of almond, peppermint,
wintergreen, rose, cassia, and cloves.

At the time the importance of a new edition seemed specially mani-
fest, the author's health was such that it would have been impossible
for him to personally undertake the work, and had it not been for his
friends it could not have been accomplished. Indeed, the work of
revision has been due to the untiring energy of Dr. A. L. Winton, Chief
of the U, S. Food and Drug Inspection Laboratory at Chicago, who
out of a busy life has taken entire charge of the details of the task,


supplying most of the new material, as well as introducing much that
is original as a result of his ripe experience. To him, therefore, above
all others, the author here expresses his deep appreciation and gratitude.

Special thanks are also extended to Dr. W. D. Bigelow, Chief of the
Division of Foods of the Bureau of Chemistry, Washington, for his
substantial work in revising the chapter on flesh foods, which includes
much of his recent research along this line; also to Dr. T. B. Osborne,
Chairman of the Committee on Protein Nomenclature of the American
Physiological Society and of the Society of Biological Chemists, who
has revised the classification of nitrogenous bodies; and finally to Mr. E.
J. Shanley for his help in reading proof.

Denver, Colorado, September, 1909.


In the preparation of the present work, the requirements of the public
analyst are mainly kept in view, as well as of such officials as naturally
cooperate with him in carrj'ing out the provisions of the laws dealing
with the suppression of food adulteration in states and municipalities.
To this end special prominence is given to the nature and extent of adul-
teration in the various foods, to methods of analysis for the detection of
adulterants, and to some extent also to the machinery of inspection.

While the analyst may not in all cases have directly to deal with the
minutlcB of food inspection, his work is so closely allied therewith that
this branch of the subject is of vital interest and importance to him.
Indeed, in many smaller cities one official often has charge of the entire
work, combining the duties of both inspector and analyst.

Endeavor has been made, furthermore, to deal with the general com-
position of foods, and to give such analytical processes as are likely to
be needed by the sanitary chemist, or by the student who wishes to
determine the proximate components of food materials.

It has been thought best to include brief synopses of processes of
manufacture or preparation of certain foods and food materials, in cases
where impurities might be suggested incidental to their preparation.

In view of the fact that Massachusetts was the pioneer state to adopt,
over twenty years ago, a practical system of food and drug inspection,
and for many years was the only state to enjoy such a system, no apology
is perhaps needed for more frequent mention of Massachusetts methods
and customs than those of many other states, in which the food laws
are now being enforced with equal zeal and efficiency.

Considerable attention has been paid in the following pages to the
use of the microscope in food analysis. Of the figures in the text illus-

viu PREFy4CE.

trating the microscopical structure of powdered tea, coffee, cocoa, and
the spices, fifteen have been reproduced from the admirable drawings
of Dr. Josef Moeller, of the University of Graz, Austria. Acknowledg-
ment is gratefully given Dr. Moeller for his kind consent to their use.

The photomicrographs in half-tone, forming the set of plates at the
end of the volume, were all made in the author's laboratory, and may
be divided into three classes: ist, illustrations of powdered pure foods
and food products, as well as of powdered adulterants; 2d, types of
adulterated foods, chosen from samples collected from time to time in
the routine course of inspection; and 3d, photographs of permanently
mounted sections of foods and adulterants.

While recent works covering the whole field of general food analysis
are comparatively few, the number of treatises, monographs, government
bulletins, and articles scattered through the journals, dealing with special
subjects relative to food and its inspection, is surprisingly large, and from
a painstaking review of these much information has been culled, for which
it has been the author's intention at all times to give credit.

Special mention sliould here be made of the valuable publications of
the U. S. Department of Agriculture, both the bulletins issued from
Washington, and those from the various experiment stations, an ever-
increasing number of which are becoming engaged in human food
work. The author has freely drawn from these sources, and especially
from the data and material furnished by his coworkers in the recent
and still pending labor of preparing food methods for the Association of
Official Agricultural Chemists, and he wishes to extend his thanks to
all of them for their assistance. Appreciation is also expressed for the
care and discrimination shown by Mr. L. L. Poates in the preparation of
the cuts. Thanks are especially due to Mr. Hermann C. Lythgoe,
Assistant Analyst of the Massachusetts State Board of Health, for his
invaluable cooperation, and to Dr. Thomas M. Drown for helpful hints
and suggestions.

Boston, Mass., July i, 1904.




Food Analysis and Official Control 1-13

Introductory, i. Food Analysis from the Dietetic Standpoint, 2. Systematic
Food Inspection; Functions of the State Analyst; Standards of Purity; Na-
ture of Analytical Methods, 3-5. Adulteration of Food, 5. Misbranding, 6.
A Typical System of Food Inspection, 6-9. Practical Enforcement of the Food
Laws; Publication; Notification; Prosecution, 10.

References on Food Inspection and Official Control, 11.


The Laboratory and its Equipment 14-38

Location, 14. Floor; Lighting; Benches, 15. Hoods, 16. Sinks and
Drains, 17. Steam and Electricity; Suction and Blast, 19. Apparatus, 20-
25. Reagents, 26-35. Equivalents of Standard Solutions; 36-37. Indica-
tors, 38.

References on Laboratory Equipment, Reagents, etc., 38.


Food, its Functions, Proximate Components, and Nutritive Value 39-52

Nature and General Composition of Food; Fats, 39. Protein, and
Classification of Nitrogenous Bodies, 40. Proteins, their Subdivisions, Occur-
rence, and Characterstic Tests, 40-45. Amino A'-ids, etc., 45. Alkaloids;
Nitrates; Ammonia; Lecithin; Carbohdyrates aad their Classification, 46.
Organic Acids; Mineral or Inorganic Materials; Fuel Value of Food;
Bomb Calorimeter, 47-48.

References on Dietetics and Economy of Food, 49.


GENER.A.L Analytical Methods 53-80

Expression of Results, 53-54. Preparation of Sample, 55. Specific Gravity;
Methods and Apparatus, 55-60. Determination of Moisture, 61. Deter-
mination of Ash, 61-63. Continuous Extraction with Volatile Solvents, 63-68.
Separation with Immiscible Solvents, 68. Determination of Nitrogen, 69-73.


Determination of Free Ammonia; Determination of Amido Nitrogen, 74.
Determination of Carbohydrates, 74. Poisoned Foods, 74. Detection and
Determination of Arsenic, 75-76. Colorometric Analysis, 77. Tintometer,
References on General Food Analysis, 79.


The Microscope in Food Analysis 81-99

Microscopical vs. Chemical Analysis, 81. Technique of Food Microscopy,
82. Apparatus and Accessories, 82-84. Preparation of Vegetable Foods for
Microscopical Examination, 85. Miscroscopical Diagnosis, 86. Vegetable
Tissues and Cell Contents, under the Microscope, 87-90. Microscopical
Reagents, 90-93. Microchemical Reactions, 90-93. Photomicrography;
Appurtenances and Methods, 93-98.

References on the Microscope in Food Analysis, 98.


The Refractometer 100-123

Butyro-refractometer, loi. Refractometer Heater, 102. Manipulation,
102-104. Equivalents of Refractive Indices and Butyro-refractometer Read-
ings, 105-106. Temperature Correction, 107. Abbe Refractometer, 108.
Construction; Manipulation, 109-111. Immersion Refractometer, 111-112.
Manipulation, 113-115. Equivalents of Refractive Indices and Immersion
Refractometer {•leadings, 116-119. Strength of Solutions by Refractometer
120. Temperature Corrections, 121.
References on the Refractometer, 122.


Milk and Milk Products 124-210

Composition and Characteristics of Milk, 124. Milk Sugar; Milk Proteins,
and other Nitrogenous Bodies, 125. Milk Fat; Citric Acid; Composition of
the Ash, 126-127. Fore Milk and Strippings, 128. Colostrum; Frozen Milk;
Fermentations of Milk, 129. Analysis of Milk, 130. Specific Gravity, 131-133.
Total Solids, 133. Ash, 134. Fat, by E.xtraction, by Centrifugal, and by Re-
fractometric Methods, 134-144. Proteins; Casein, 145. Albumin; Other
Nitrogenous Bodies, 146. Milk Sugar, by Optical Methods, 147 149, by
Fehling's Solution, 149-151. Relation betvi'een the Various Milk Constituents;
Calculation by Formulae, 151-153. Acidity, 153. ^^oiled Milk, 155. Modi-
fied Milk and its Preparation, 155-157. Prepared Milk Foods, Milk Powders,
and Artificial Albuminous Foods, 157-159. Koumis, 158. Kephir, 159.

Milk Adulteration and Inspection; Milk Standards, 159-161. Forms of
Adulteration, and Variation in Standard, 161-162. Rapid .\pproximate
Methods of Examination, 163-164. Examination of Milk Serum; Constants,
164-168. Systematic Routine Examination, 168. Analytical Methods for
Solids, Fat, and, 170-173. Added Foreign Ingredients. 173. Coloring
Matters and their Detection, 174-177. Preservatives, their Relative Efficiency



and their Detection, 177-185. Added Cane Sugar, and Starch, 185. Added
Condensed Milk; Analysis of Sour Milk, 186.

Condensed Milk; Composition, Standards, Adulteration, 186-188. Methods
of Analysis, 188-191. Calculation of Fat in Original Milk, 192.

Cream; Composition, Analytical Methods, Standards, Adulterants, 193-195.
Gelatin in Cream, 195-196. Sucrate of Lime in Cream, 196-198.

Ice Cream; Standard, Fillers, 198-199. Analytical Methods, 199-201.

Cheese; Composition, Varieties, 201-202. Standards; Adulteration,
203-204. Analytical Methods, 188-191. Separation and Determination of
Nitrogenous Bodies, 205-206. Lactic Acid; Milk Sugar; Foreign Fat, 207.

References on Milk and its Products, 208.


Flesh Foods 21 1-260

Meat; Structure and Composition, 211. Proximate Components of the
Common Meats, 212-217. Meat Inspection, 217. Standards, 218. Meat
Preservatives, 218. Curing, 219. of Antiseptics; Effect of Cooking, 220.
Canned Meats, 221. Sausages, 223-224. Analytical Methods, 225. Fats
of Meats, 226-227. Classification, Separation, and Determination of Nitrog-
enous Bodies, 228-231. Determination of Gelatin, 231. Determination of
Nitrates, 232. Preservatives and their Detection, 232. Starch in Sausages,
233. Horseflesh in Sau.sages, and its Detection, 234-238. Muscle Sugar, 238.
Coloring Matters and their Detecticn, 238-239. Detection of Frozen Meat,

Meat E.xtracts; Character and Standards, 240-241. Composition, 242-244.
Meat Juices, 245. Miscellaneous Meat Preparations, 246. Methods of
Analysis, 246-249. Separation of Nitrogenous Compounds, 249-253. Acidity,
253. Preservatives; Glycerol, 254.

Fish; Structure Composition, and Methods of Analysis, 254-255. Crus-
taceans and Mollusks, 256. Analytical Methods; Preservatives in Fish and
Oysters, 257.

Concentr:,t-'d Foods for Armies and Campers, 257.

References on Flesh P'oods, 258.


Eggs 261-270'

Nature and Composition, 261. The Egg White and its Nitrogenous Com-
pounds, 262. Prej)aration of Albumin; The Egg Yolk and its Composition,
263. Composition of the Ash, 264. Analytical Methods; Determination of
Lecithin, 265. Preservation of Eggs, 266. Cold Storage Eggs, 267. Physical
Methods of Examination, 267. Opened Eggs; Desiccated E^ggs, 268. Egg
Substitutes, 269. Custard Powders, 270.
References on Eggs, 270.




Cereals and their Products, Legumes, Vegetables, and Fruits 271-364

Composition of Cereals, Vegetables, Fruits, and Nuts, 271-276. Methods
of Proximate Analysis, 276-279. Carbohydrates of Cereals, 279. Starch;
Detection, Varieties, Classification, Microscopical Examination, 279-283.
Starch Determination, by Direct Acid Conversion and by Diastase Methods,
283-284. Cellulose; Crude Fiber, 285. Pentosans and their Determination,
285-294. Separation and Determination of the Carbohydrates of Cereals, 295-
296. Proteins of Cereals and Vegetables; Sepiration and Methods of Analysis,
296-298. Proteins of Wheat, their Separation and Determination, 298-300.
Proteins of Other Cereals and Vegetables, 300-301. Ash of Cereals and
Vegetables; Scheme for Ash Analysis, 301-305. Microscopy of Cereal Pro-
ducts, 305-311.

Flour; Milling, 311. Composition, 312. Damaged Flour; Ergot, 313.
Adulteration, 314. Alum; Bleaching, 315. Inspection and Analysis; Fine-
ness, 316. Pekar's Color Test; Absorption and Dough Test; Expansion of
Dough, 317. Baking Tests, 317-319. Proximate Constituents; Gluten, 319.
Protein; Acidity, 320. Detection of Bleaching; Nitrites, 321. Bamihl Gluten
Test, 322.

Bread; Composition; Varieties, 323-325. Methods of Exar in tion, 325-
326. Adulteration of Bread; Alum, 326. Cake, 327.

Leavening Materials; Yeast, 327. Compressed Yeast; Dry Yeast, 328.
Composition and Microscopical Examination, 329. Yeast Testing; Available
Carbon Dioxide, 330. Starch in Compressed Yeast, 331.

Chemical Leavening Materials; Baking Powders, their Classification and
Composition, 332-334. Adulteration, 334. Cream of Tartar and its Adultera-
tion, 335. Analysis of Baking Chemicals, 336. Carbon Dioxide, 336-339.
Tartaric Acid, 339-343- Starch, 343. Aluminum Salts, 344. Other In-
gredients, 345-346.

Semolina, Macaroni, and Edible Pastes; Noodles, ^547-348. Adul-
teration; Analytical Methods; Lecithin-Phosphoric Acid, 349. Colors, 349-
352. Shredded Wheat, 352.

Prepared Cereal Breakfast Foods; Nature and Composition, 352-354.
Analytical Methods, 354.

Infants' and Invalids' Foods, 354. Classification, 355. Composition, 356.
Diabetic Foods, 357-358. Analytical Methods, 359-360.

References on Cereals, Vegetables, etc., 361.

References on Leavening Materials, 364.


Tea, Coffee, and Cocoa 365-407

Tea; Varieties, Method of Manufacture, Composition, 365-368. Analytical

Methods, 368. Extract; Tannin, 370-372. Theine, or Caffeine, 372-374.

Adulteration and Detection of Adulterants; Facing, 374. Spent Leaves, 375.

Foreign Leaves; Stems and Fragments, 376. Added Astringents; Tea Tablets,

377. Microscopical Structure, 378.

Coffee; Nature, Composition, Effect of Roasting, 379-381. Substitutes

and Adulterants, 382. Analytical Methods; Caffetanic Acid, 382-383.



Caffeine, 384. Adulteration; Imitation Coffee; Coloring, 384. Glazing;
Methods, 385. ]\Iicroscopical Examination, 386. Chicory; its Microscopical
Structure, 386-388. Composition of Chicory, and its Determination in Coffee,
389. Date Stones; Hygienic Coffee; Substitutes, 390-392.

Cocoa and Cocoa Products; Composition, Methods of Manufacture, 392-
395. Theobromine and Nitrogenous Substances, 396. Milk Chocolate; Com-
pounds, 397. Analytical Methods, 398. Starch; Sucrose; Lactose, 399.
Theobromine and Caffeine, 400-401. Adulteration, and Standards of Purity,
402. Addition of Alkali, Microscopical Structure, 403-404. Cocoa Shells;
Added Starch, Sugar, Fat and Colors, 405.

References on Tea, Coffee, and Cocoa, 406.


Spices 408-470

Methods of Proximate Analysis Common to all the Spices, 408. Moisture;
Ash; Ether, and Alcohol Extract; Nitrogen; Starch; Crude Fiber; Volatile
Oils, 409-411. Microscopical Examination, 412. Spice Adulterants, 412-413.

Cloves; Composition, 412-415. Tannin, 415. Microscopical Examination,
416. Clove Stems, 417. Adulteration and Standard of Purity; Exhausted
Cloves, 418. Cocoanut Shells, 419.

Allspice; Composition, 420. Tannin Equivalent, 421. Microscopical
Structure, 422-423. Adulteration and Standard of Purity, 424.

Cassia and Cinnamon; Composition, 424-425. Microscopical Structure,
426-427. Adulterants; Standard, 428. Foreign Bark, 428.

Pepper; Composition, 428-432. Nitrogen Determination, 432. Piperin,
433. Microscopical Examination, 433-434. Adulteration and Standards, 435.
Pepper Shells and Dust, 435. Olive Stones, 436. Buckwheat, 437. I>ong
Pepper, 438.

Red Pepper; (Cayenne, Paprika, etc.). Nature; Varieties: Composition,
439-441; Microscopical Structure, 441-443. Adulteration, 443-445. Added
Oil in Paprika, 445.

Ginger; Composition, 445-446. Exhausted Ginger, and its Detection, 447-
448. Microscopical Structure, 449. Adulteration and Standard, 450.

Turmeric; Composition, 450. Microscopical Structure, 451. Detection,


Mustard; Composition, Preparation, 453-456. Mustard Oil Determina-
tion, 457. Microscopical Structure, 458. Adulteration and Standards, 459.
Coloring Matter, 460. Prepared Mustard; Composition, Adulteration, 460.
Analytical Methods, 461.

Nutmeg and Mace; Composition of Nutmeg, 462-463. Microscopical Struc-
ture of Nutmeg; Adulteration; Standard of Purity, 464. Composition of
Mace, 465. Microscopical Structure; Adulteration; Standard, 466. Bom-
bay or Wild Mace and its Detection, 467. Macassar Mace, 468.

References on Spices, 468.


(■iiai"'I'i;r \iii.


l'j)iiii.i'; Oils and I*' a is 47 r 564

Nature and I'roijcrtics, 471 . I'atly Acids, 471 472. Saponilkation, 472.
Analysis; Raruidity; Jud^incnt as to I'urity; I'iltcring, Weighing, and
Measuring I'ats, 47.5. Specific: (Gravity, 474 476. Viscosity, 477. Melting-
point, 4X0. Keicliert-Meissl Process for Volatile l-atty Acids, 481-482. Po-
icnske Number, 485. Soluble and Insoluble I'alty Acids, 484 486. Sa[)onifica-
tion Number, 486. Iodine Absorption Number; Uubl's Method, 487 490.
nanus's Method, 491. Wijs's Method, 492. Bromine A])Sor[)tion Number,
49249,^. 'rhermalTests, 493. Maumen(^ Test, 494. Hrominalion Test, 494-
497. The Acetyl Value, 497-498. The Valcnta and iviaidin 'IV.sts, 499.
Free I''atly Acids, soo- Titer Test, 500 501. Un.saijonifiable Matter, 501.
Cholesterol .iiid i'hylostciol, 502. Se|)aralion and Crystallization, 503-506.
B(")mer's i'liytoslcrol A(clale 'i'esi, 507. Conslaiils of iMJible Oils and Fats,
508 509. Parrairni; M i( roscopii a! iOxamiiiallion of ( )ils and I'ats, 510.
Olive Oil, 511. Composition and Adulteration, 512. Standards, 513. Tests
for Adulteration, 513-515. Cottonseed Oil, 516. liechi's 'lY'st, 517. Ilal-
phen's Test, 518. Sesame Oil, 518, .Adulterants and'I'ests, 519. Rajie Oil,
520. Tests, 521. ('orn Oil, 521. Sitosterol, 522. I'eanut Oil, 522. Adul-
terants; Keiuird's Method, 523. Bellier's Method, 524. Mustard Oil, 525.
Poppy.seed Oil, 526. Sunflower Oil, 526. Rosin Oil, 527. Cocoaiml Oil, 528.
Cocoa Butter; Tallow, 529.

Butler, 529. Composition, 530. lOffecIs of I'ceding, 531. .Xiialytical
Methods, 531. Water, 531 533. I''at, 533. Ash; Casein; Milk Sugar;
i.aclic Acid; Sail, 534. Standard Buder l''al, 535. .Adulteration, 535.
Colors, 535 537. i're.scrvalives, 538 53(). Renovated or Process Butter, 540.
Oleomargarine; Manufacture, 541. Coloring; Detection of I'alm Oil, 542.
Adulterants; llealthfulness, 543. Distinction from Butter, 544. Distin-
guishing Tests for Bulter, Process Butter, and Oleomargarine, 546. ikityro-
refractonieter, 54^) 548. keichert Meissl Number; S|)eciric (iravity; Foam
Test, 549. Milk 'I'est, 550. Curd Tests, 551. Microscopical iCxaminalion,
552-55,?- I'"'>i"<'ign Oils, 554.

Lard, 554. Composilion; Lard ( )il, 555. Coni|)ound Lard; Standards;
Adulteration, 550. P'oreign Oils, 557. Micro.scopical F.xamination, 557 558.
Analysis of Lard and Lard Substitutes, 559. Fffects of I'\r(ling, 560.

References on Ivlible ( )ils and I'"ats, 561. Refc-rences on I>utter, 562. Refer-
ences on Lard, 563.

CIIAI'Tl.k \1\'.


Nature and ChLssihcation, 565. Cane Sugar; Standard, 566. Sugar Cane;
Manufacture of Cane Sugar, 567. Com|)osition of Cane Sugar IVoducls, 568.
Sugar Beet; Manufacture of Beet Sugar, 569. Refining Sugar; Maple Pro-
ducts, 750. Ct)m])ositions, Standards, and Adulteration of Maple Products,
571-572. Sorghum, 573. Crape Sugar, 573.; Malt Sugar, 574.
Dextrin; Commercial Clucose, 575. Standards and llealthfulness of (ilucose,
570. Milk Sugar; Rallinose, 577.



The Polariscope and Saccharimetry, 578-583. Comparison of Scales and
Normal Weights, 583. Specific Rotary Power; Birotation, 584.

Analysis of Cane Sugar and its Products; Tests for Sucrose, 585. Moisture;
Ash; Xon-sugars; Sucrose Determination by Polariscope, 586-587. Inversion;
Clerget's P'ormuia, 588. Detection and Determination of Invert Sugar, 589.
Ultramarine in Sugar; Copper Reduction, 590. Volumetric Pehling iVocess,
591-592. Gravimetric Tehling Methods, 593. Defren-O'Sullivan Method,
594-597. Mun.son and Walker Method, 598-607. Allihn Method; Elec-
trolytic Apparatus 608-612. Sucrose Determination by Fehling Solution, 612.

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