Detection of the common food adulterants

Preface

Because of the recent agitation of the pure food question throughout the country, health officers, food-inspectors, and chemistry teachers and students are constantly called upon to test the purity of various foods. And this usually involves nothing more than making simple qualitative tests for adulterants. In view of the fact that there is now no text or manual devoted exclusively to the qualitative examination of foods, this little book is offered to those who are interested in this work.

Its aim is to bring together in one small book the best and simplest qualitative tests for all the common food adulterants. It contains a brief statement of the adulterants likely to be found and the reason for their use. It is hoped that it will be specially valuable to chemistry teachers in furnishing excellent supplementary work in qualitative analysis. But it is hoped that it will find its greatest usefulness in contributing something toward the great pure food reform.

It is impossible to make due mention of all the sources from which these various tests have been collected, but where possible, the author's name has been associated with the test.

Terre Haute, Ind.

March 25, 1907.

Table Of Contents

CHAPTER I page

Dairy Products i

Milk — Adulterations of — Coloring matters — Annatto

CHAPTER II Meats and Eggs 8

Adulterations of — Fresh and smoked — Preservatives — Potassium nitrate — Boric acid — Sulfurous acid

— Salicylic acid — Benzoic acid — Canned — Preservatives (same as those of fresh and smoked meat) — Heavy metals — Coloring matter (see under sausages, etc.) — Fish, salt, dried and oysters — Preservatives — Boric acid (same under smoked and fresh meat) — Coloring matter — Aniline red and cochineal-carmine — In sausages, chopped meat, preparations and corned meat — Starch — In sausages, deviled meat and similar products — Diseased meats — Horse-flesh in sausages and in mince-meat.

Eggs — Test for age.

CHAPTER III Cereal Products 16

Flour — Adulteration of — Alum — Copper sulfate — Substituted flours — General test — Corn meal in wheat flour — Wheat flour in rye flour — Ergot in rye flour.

Bread — Adulterations of — Alum — Copper sulfate.

Ginger Cake — Adulterations of — Stannous chlorid. v vi CONTENTS

CHAPTER IV page

Leavening Materials 20

Baking Powders — Adulterations of — Tartaric acid (free or combined) — Tartaric acid (free) — Sulfates (calcium, etc.) — Gypsum — Ammonium salts — Alum.

Cream of Tartar — Adulterations of — Tartaric acid (free or combined) — Aluminium salts — Ammonia — Earthy materials.

Chapter V

Adulterations of — Preservatives — Preparation of sample — Formaldehyde — Sulfurous acid and the sulfites — Salicylic acid — Saccharin — Benzoic acid — Coloring matter — Cochineal — Coal-tar dyes — Copper salts — In green pickles, beans, peas, etc. — Turmeric — In mixed pickles — Heavy metals (other than copper, same as under meats) — Soaked vegetables — Peas, beans and corn — Alum — In pickles — Examination of the can or box.

Chapter VI

Adulterations of — Preservatives — Preparation of sample — Salicylic acid — Benzoic acid — Saccharin — Coloring matter — Coal-tar dyes — Cochineal — Acid magenta — Apple juice in jellies made from small fruits — Detection (see test for starch) — Starch — In jellies, jams and such products — Gelatin — In jellies — Agar agar — Heavy metals — Arsenic.

Chapter VII

Lemon Extract — Lemon oil — Citral — Oil of citronella — Tartaric or citric acid — Methyl alcohol — Coloring matter — Turmeric — Coal-tar colors.

Vanilla Extract — Adulterations of — Preliminary test — Alkali — Foreign resins — Caramel — Tannin — Coumarin.

CONTENTS vii

CHAPTER VIII page

Saccharine Products 49

Honey — Adulterations of — General observations — Cane sugar — Commerical glucose syrup — Gelatin.

Maple Syrup — Adulterations of — General examination — Glucose.

CHAPTER IX Spices . 51

Mustard — Adulterations of — Flour — Coloring matter — Turmeric — Martius yellow or analogous coal-tar coloring matter — Cayenne pepper.

Pepper — Adulterations of — General test — Ground olive stones — Cayenne pepper.

Chapter X

Adulterations of — Preparation of sample — General observations — Free mineral acids — General tests — Sulfuric acid — Hydrochloric acid (free) — Malic acid — Coloring matter — Caramel — Coal-tar colors — In wine vinegar — Free tartaric acid — In wine vinegar.

CHAPTER XI Fats and Oils 60

Lard — Adulterations of — Cottonseed oil — Cottonseed stearin — Beef stearin.

Olive Oil — Adulterations of — General test — Cottonseed oil — Peanut oil — Sesame oil — Rape oil.

CHAPTER XII Beverages 65

Coffee — Adulterations of — General test — Coloring matter — Imitation coffee beans — Chicory.

Tea — Adulterations of — Foreign leaves — Exhausted tea leaves — Lie tea — Facing — Catechu.

Chapter I Dairy Products

MILK

Milk is adulterated by watering, removing the cream or by adding some foreign substance. Formaldehyde, boric acid or salicylic acid may be added to preserve the milk. Annatto, caramel or some coal-tar dye is added, sometimes to improve the color of the milk, and at other times to cover up traces of watering. Gelatin and starch are added for the same purpose, though they are not frequently used.

ARTIFICIAL COLORING MATTER

Annatto

Add acid sodium carbonate to a sample of the milk until it shows a slight alkaline reaction. Immerse a piece of filter-paper and leave it in for 12 or 15 hours. If annatto is present, there will be a reddish-yellow stain on the paper.

Leach's Method. — Warm 150 cc. of the sample and add 5 cc. of acetic acid, then continue heating it nearly to the boiling point, stirring while it is being heated. Separate the curd by gathering it with the stirring rod or by pouring through a sieve. Press out all the whey from the curd and macerate the latter for several hours (10 to 12 hours) in 50 cc. of ether. It is best to do this in a tightly corked flask, shaking it frequently. If the milk was uncolored or colored with annatto the curd when thus treated will be white. If the curd is a dull brown color caramel was probably used to color the milk. Confirm its presence by shaking a portion of the curd with concentrated hydrochloric acid (sp. gr. 1.20) and gently heating. If the acid solution turns blue while the curd does not change its color, caramel was used to color the milk. (Remember that the etherextracted curd must be brown.)

Coal Tar Colors

Lythgoe's Method. — Mix in a porcelain vessel about 15 cc. each of the sample of milk and hydrochloric acid (sp. gr. 1.20) and break up the curd into coarse lumps by shaking gently. If an azo-color was used to color the milk this curd will be pink, but the curd of normal milk will be white or yellowish.

The presence of starch in milk may be detected by heating a small quantity of the milk to boiling. When it has cooled add a drop of iodin in potassium iodid, and if starch is present there will be a blue coloration.

A . W. Stokes 1 Method. — Dissolve 1 part by weight of mercury in 2 parts of nitric acid (sp. gr. 1.42). Add 24 times this volume of water. Mix equal volumes (about

DAIRY PRODUCTS 3

10 cc.) of this reagent and the milk or cream, shake well and add 20 cc. of water. Shake again and, after standing 5 minutes, filter. When a great quantity of gelatin is present the filtrate will be opalescent instead of perfectly clear. To a little of this filtrate in a test tube add the same volume of a saturated aqueous solution of picric acid. If much gelatin is present a yellow precipitate is produced, smaller amounts produce a cloudiness. If the filtrate is perfectly clear gelatin is absent and picric acid may be added without producing any noticeable effect.

Formaldehyde

Hehner's Sulfuric Acid Test. — Put 10 cc. of the suspected milk in a wide test tube and pour carefully down the side of the inclined tube about 5 cc. commercial sulfuric acid so that it forms a separate layer at the bottom. A violet coloration at the union of the two liquids indicates the presence of formaldehyde. If the commercial acid is not available, the pure acid may be used, but a few drops of ferric chloride must be added. Sometimes the charring effect of the acid makes it advisable to use the following test:

Hydrochloric Acid Test. — 2 cc. of 10 per cent ferric chloride is added to one liter of commercial hydrochloric acid sp. gr. 1. 2 (or any quantity in this proportion). To 10 cc. of this mixture add 10 cc. of the milk to be tested. Heat the mixture slowly nearly to the boiling point, in an evaporating dish, but agitating it all the while to prevent the curd collecting in one mass. If formaldehyde is present, .there will be a violet coloration. It is said that by this test as small a quantity of formaldehyde as i part in 250,000 parts of milk can be detected. It is not so sensitive in sour milk.

Turmeric Paper Test. — Incinerate some of the milk, and acidulate the ash with a very few drops of dilute hydrochloric acid and afterwards dissolve it in a few drops of water. Place a strip of turmeric paper in this solution for a few minutes, then remove and dry it. If boric acid either free or combined is present, the turmeric paper will be turned to a cherry-red color.

Another way oj making this test. — U. S. Dep. of Agr., Div. of Chem., Bui. 65, p. no: Make strongly alkaline with lime water, 25 grams of the milk, and evaporate to dryness on the water bath. Destroy the organic matter by igniting the residue. Dilute with 15 cc. of water and acidify with hydrochloric acid. Then add 1 cc. of the concentrated acid. Dip a piece of delicate turmeric paper in the solution; and if borax or boric acid is present, it will have a characteristic red color when dry. Ammonia changes it to a dark blue green, but the acid will restore the color.

(Turmeric paper may be prepared by dipping pieces of smooth, thin filter paper in a solution of powdered turmeric in alcohol.)

(This is not often used as a preservative of milk.) Leach suggests the following method for its detection. — Dissolve one gram of mercury in 2 grams of nitric acid (sp. gr. 1.42) and then add to the solution the same volume of water. Add 1 cc. of this reagent to 50 cc. of the milk to be tested, and shake and filter. The perfectly clear filtrate is

DAIRY PRODUCTS 5

shaken with ether and the ether extract evaporated to dryness. Then add a drop of ferric chlorid solution, and a violet color will be produced if salicylic acid is present.

BUTTER

Butter is often colored with annatto, saffron, turmeric, marigold or coal-tar colors. By a certain process, stale or old butter is sometimes worked over and made to appear fresh for a time. This is sold under the name of "process" or "renovated" butter. Foreign fats like cottonseed oil, sesame oil, or oleomargarine may be substituted for or added to pure butter.

Martin's Test. — Add 2 parts of carbon bisulfid, a little at a time and with frequent shaking, to 15 parts of alcohol. Shake 25 cc. of this solution with 5 grams of the butter, and let stand for some time. The carbon bisulfid dissolves out the fatty matter and settles to the bottom. The alcohol remains on top and will dissolve out any artificial colors that may be present. If only a little coloring matter is present use more of the butter.

Annatto Evaporate a portion of the extract to dryness and add sulfuric acid to the residue. If annatto is present a greenishblue color forms. Should a pink tint result the presence of a coal-tar color is to be suspected.

Coal-Tar Colors These colors will dye wool or silk if pieces of the fiber are boiled in the diluted alcoholic extract, which has first been acidified with hydrochloric acid. The normal butter coloring matter will not dissolve when thus treated.

Geislefs Method. — To a few drops of the clarified fat on a porcelain surface, add a very little fullers' earth. If a pink to violet-red coloration is produced in a short time the presence of an azo-color is indicated.

Saffron

When saffron is present, nitric acid colors the alcoholic extract green, and hydrochloric acid colors it red.

Add ammonia to the alcoholic extract, and if it turns brown it indicates the presence of turmeric.

Marigold

Add silver nitrate to the extract, and if it turns black the presence of marigold is indicated.

Process or Renovated Butter

Heat a little of the suspected butter in a spoon or dish, and if it is process butter it will sputter, but not foam much. Make the test also with some butter known to be pure and fresh.

Hess and Doolittle Test. — Melt some of the butter (say 40 grams) at about 50 C. If the butter is pure and fresh the melted fat will clear up almost as soon as it is melted, while the fat of process butter remains turbid for quite a while. After most of the curd has settled, decant as much as possible of the fat. Pour the remainder on a wet filter. Add a few drops of acetic acid to the water that runs through from the filter, and boil. If it was ordinary butter

DAIRY PRODUTCS 7

this filtrate will become milky, but if process butter a flocculent precipitate will form.

Oleomargarine

Immerse a test tube, containing some of the filtered fat, in boiling water for 2 minutes. Make a mixture of 1 part glacial acetic acid, 6 parts ether, and 4 parts alcohol. Add to 20 cc. of this mixture in a 50 cc. test tube, 1 cc. of the heated fat which may be transferred by means of a hot pipette. Stopper the tube and shake it well. Immerse in water at 15 or 16 C. Pure butter when thus treated remains clear for quite a while. There will be only a very little deposit after standing an hour, but oleomargarine gives a deposit almost immediately, and in a few minutes there will be a copious precipitate.

When the oelomargarine in butter is in about the proportion of 1: 10, it will not separate much short of 15 minutes.

The presence of this oil may be detected by Halpen's test, which is given under lard, page 60.

Chapter II Meats And Eggs

Meats are preserved by treating them with potassium nitrate, boric acid, sulfurous acid, salicylic acid, or benzoic acid. Cheap meat may be substituted for the more expensive. A few cases of horse meat in mince meat and sausages have been discovered. Diseased and stale meats have been found on the market. Canned meats often contain zinc, tin, and lead, and sometimes even arsenic. Aniline-red or cochineal-carmine may be added to improve the color of chopped or ground meats. Starch is sometimes added to sausage and similar meat. Fish and oysters may be preserved with boric acid or borax.

FRESH AND SMOKED PRODUCTS — PRESERV- ATIVES

Potassium Nitrate (Saltpeter)

Corned and smoked meats are usually preserved with saltpeter. Since smoked and cured meats are used in making potted meats, saltpeter is quite frequently found in the latter. It may be detected by the usual test for nitrates since no other nitrate is apt to be present, though one may identify the metal by the qualitative test for potassium.

To test for nitrates treat a little of the meat with 2 or 3 cc. of a 1 per cent solution of diphenylamine in strong sulfuric

MEATS 9

acid. If a nitrate is present a deep blue color forms instantly, which is not obscured by the charring effect of the acid.

Pick apart into fine pieces about 25 or 50 grams of the lean meat and warm with a little water which has a few drops of hydrochloric acid in it. Soak a piece of turmeric paper in the extract, and if boric acid is present the paper will be colored rose-red when it is dry. A weak alkali turns this colored paper olive.

Another method is to burn a piece of the meat to an ash, after being treated with lime water. Make a solution of the ash and make slightly acid with hydrochloric acid. Then test with the turmeric paper with the same results as in the above method.

Sulfurous Acid

U. S. Dep. Agr., Bureau Chem., Bui. 13, Part 10: Digest 40 or 50 grams of the meat in hot water, treat with 10 cc. glacial phosphoric acid to coagulate the proteids. Strain through a cotton bag and transfer the filtrate to a short-necked flask and distil receiving the first part of the distillate in a solution of iodin. Boil, and add barium chloride. If sulfurous acid is present, it will be oxidized to sulfuric acid and precipitated as barium sulfate by the barium chlorid. More than a mere trace of the precipitate proves that some sulfite was used to preserve the meat.

Another method suggested by Kammerer is to place the meat on paper, which has been saturated with potassium iodate moistened with dilute sulfuric acid (1:8); nitric oxid must not be present. If sulfurous acid is present a deep io PURE FOOD TESTS

blue color forms at once. A trace of this color may form after some time with meat that is not fresh, hence this method cannot be used in examining canned meat.

Heat 50 grams of the meat in 50 cc. of water. Add 10 cc. of a strong solution of glacial phosphoric acid and strain through a cotton bag. Extract the filtrate with a little ether (about 50 cc.) in a separatory funnel. Let the ether evaporate spontaneously. Take up the residue with 3 cc. of water, and add one or two drops of a one-half per cent solution of ferric chlorid. If salicylic acid is present the mixture will be purple or violet.

Leach makes the same test by slightly acidifying a portion of the lean meat, then extracting with ether, and evapporating to dryness and testing the residue with a drop of ferric chlorid solution. A deep violet coloration is produced if salicylic acid is present.

Mohler's Method. — Prepare a sample as in the test for salicylic acid by heating 50 grams of the meat in 50 cc. of water. Add 10 cc. of a concentrated solution of glacial phosphoric acid, and strain through a cotton bag. Neutralize with sodium hydrate and evaporate to dryness or to a small volume. After treating with 3 cc. of concentrated sulfuric acid, heat till white fumes appear. Add 4 or 5 crystals of potassium nitrate and continue heating until the solution is colorless or nearly so. When cool dilute with water, add an excess of ammonia, and place in a narrow vessel like a test tube. Add one or two drops of ammonium sulfid carefully so that the liquids do not mix. If the surface of

MEATS ii

the liquid immediately becomes red, benzoic acid is present.

If this test is not carefully performed, it is worthless, as other substances give similar results.

Confirm its presence by neutralizing the aqueous solution of the extracted benzoic acid with sodium hydroxid; concentrate to a very small volume. Acidify with sulfuric acid. A white flocculent precipitate shows the presence of considerable benzoic acid.

CANNED MEAT

If in preparing canned meat only fresh meat is used, there is little need for the use of preservatives, but as considerable smoked and cured meat is thus used, preservatives may find their way into canned meat.

The same preservatives should be looked for as in fresh and smoked meat and the same test made for each.

Heavy Metals

A. H. Allen's Method. — About 25 grams of the substance is mixed slowly with enough strong, pure sulfuric acid to just moisten the mass, avoiding an excess. Heat on a water-bath for a short time, then raise the temperature gradually, and maintain till the chlorids seem to be decomposed. It must not be hot enough, however, to volatilize the sulfuric acid. Then add 1 cc. of strong nitric acid and heat till red fumes are given off. Freshly ignited magnesia in the proportion of 0.5 gram for each cc. of sulfuric and nitric acid previously used is now stirred into the mass and the whole ignited at a dull red heat. This is best done in a gas-muffle. When cool, moisten the ash with nitric acid and gently re-ignite, repeating this treatment till the carbon is entirely consumed. Treat the residue with 8 or 10 drops of strong sulfuric acid, heat till fumes are given off, cool, boil with water, dilute to about ioo cc. and saturate with hydrogen sulfid, filter, examine as follows:

Zinc and iron may be in solution. Add bromine water to destroy hydrogen sulfid and to oxidize the iron, boil and add ammonium hydrate in excess, boil again and filter.

Lead, tin, copper, and calcium, if present, will be in the precipitate and residue. Fuse the mass in a porcelain crucible for at least ten minutes with 2 grams each of potassium and sodium carbonates and half as much sulfur.

After cooling, boil with water and filter.

The precipitate will contain the iron and the phosphates.

Filtrate, when blue, proves the presence of nickel.

Residue. Add hydrochloric acid and boil as long as hydrogen sulfid is given off.

A few drops of bromine water will complete the oxidation of the copper sulfid.

Filter, and add ammonium hydroxid in excess to the filtrate. When the filtrate is blue, it indicates the presence of copper. Acidify the filtrate with acetic acid and test for lead by adding potassium chromate, a yellow precipitate being formed when it is present.

The filtrate may contain tin.

Acidify with acetic acid, and if tin is present a yellow precipitate of stannic sulfid will form.

I. Heat to boiling and add potassium ferroc yanid. A white precipitate or turbidity indicates zinc.

MEATS 13

FISH SALT DRIED AND OYSTERS

This kind of meat is often preserved with boric acid and borax. They may be detected by the method given under fresh and smoked meat.

Sausages and other chopped meat preparations, together with corned meat that has been cured without saltpeter, are often treated with artificial coloring matter.

Aniline red and cochineal carmine are usually employed for this purpose. The former may be detected, according to Allen, by picking the meat apart and treating it with methylated spirit, strain or filter the extract and take up with water. Then a piece of white wool (nun's veiling will do) is immersed in the boiling liquid and, if it is dyed red, rosaniline is present.

Cochineal-carmine may be detected by the method used by Klinger and Bujard. Cut up fine about 20 grams of. the meat and heat in a water-bath with water and glycerine mixed in equal parts. If the above coloring matter is present the liquid will become quite red in color, if not present a slight yellow color results from this treatment. If a spectroscope is available this dye is easily recognized.

In Sausage, Deviled Meat, and Similar Products Cracker and bread crumbs are often added to these preparations and their presence is best detected by examining the amount of starch present. Do this by boiling some of the sample in water, and when cool adding a drop or two of iodin reagent. The usual blue color is produced if much i 4 PURE FOOD TESTS

starch is present. If there is only a little starch, it may be necessary to examine it under the microscope to determine whether the starch is from the pepper and other spices used or from some cereal.

DISEASED MEAT

The following method is recommended by Ebers. — Hold a small piece of the suspected meat over a mixture of i cc. hydrochloric acid, 3 cc. alcohol, and 1 cc. of ether. The formation of ammonium chlorid fumes shows that decomposition has begun. Do not mistake the fumes of the acid for those of ammonium chlorid.

HORSE FLESH In Sausage and Mince Meat

This sophistication is not common in this country. Horse flesh is detected by testing for glycogen, which is present in it in larger quantities than in other meats.

Courley 6° Coremon's Test. — Boil 50 grams of the meat for a half hour with water, strain, and to a portion of the filtrate add a few drops of potassium iodid-iodin solution (potassium iodid 0.4 gram; iodin 0.1 gram; water 20 cc). If considerable horse meat is present the glycogen will color the liquid dark brown, which disappears on heating, but returns on cooling.

EGGS

It sometimes happens that one wishes to know the age of eggs without opening them.

Delarne's Test. — Place the egg in a 10 per cent solution of common salt. Perfectly fresh eggs sink to the bottom.

MEATS 15

Those remaining immersed, but suspended in the liquid, are. at least three days old, while those rising to the surface and floating are more than five days old. The older the egg, the higher it floats and the more it will stand on end. This test is not applicable to eggs that have been preserved.

Hold the egg between a bright light and the eye, and if the air chamber is small, and no dark spots but instead a rather uniform rose-colored tint is seen, the egg is fresh. If the contents appear cloudy and the air chamber larger, the egg is not fresh. The darker the contents of the egg the older it is.

Chapter III Cereal Products

FLOUR

Sometimes a cheaper or inferior grade of flour is substituted for one of higher quality, and even a different kind of flour may be substituted, as corn meal in wheat flour, or wheat in rye flour. Alum may be added by millers to cover up traces of bad flour, and by bakers to make the bread white when a bad or cheap flour is being used. Copper sulfate also may be added to improve the appearance. Occasionally rye flour is made from rye upon which ergot has developed. Stannous chlorid and potassium carbonate are added to ginger cake to give the same color to the product made of molasses and a poor grade of flour as that made from good flour and honey.

ALUM

Wynther Blyth Method. — Add a little water to the sample and macerate. Soak pieces of gelatin in the solution and leave for a half day, remove the gelatin and dip the pieces in a mixture of equal volumes of a fresh tincture of logwood and a saturated solution of ammonium carbonate. The gelatin strips will turn blue if alum is present.

Bell & Carter Method. — Make a fresh 5 per cent tinc- 16

CEREAL PRODUCTS 17

ture of logwood in methyl alcohol. Dampen about 10 grams of the flour with water and add 1 cc. of the logwood tincture and the same quantity of a saturated solution of ammonium carbonate. Pure flour gives a pinkish color which fades to buff or brown. The presence of alum produces a lavender or bluish tint which becomes more distinct as it dries.

COPPER SULFATE

This adulterant may be detected in either flour or bread, by soaking the flour or bread in a dilute solution of potassium ferrocyanid acidulated with acetic acid. If copper be present a purplish or reddish-brown coloration will be produced.

SUBSTITUTED FLOURS

VogePs Method. — Make a mixture of alcohol (70 per cent), 95 parts, hydrochloric acid 5 parts. Treat a sample of the flour in a test tube with this reagent. Shake well. Heat to boiling and allow to settle. A colorless fluid shows the flour to be pure, a straw-colored tint indicates the presence of gruffs with bran, an orange- yellow proves the presence of corn-cockle flour, a flesh-colored liquid indicates the presence of ergot, while a green color indicates buckwheat flour.

Corn Meal in Wheat Flour

Kraemer claims to be able to detect as small amount as 5 -per cent of maize in wheat flour, by the following test. — Mix a gram of the flour with 15 cc. of good glycerin, and heat to boiling for a short time. If corn meal is present, there will be an odor like that of pop corn.

Wheat in Rye Flour

Kleeburg recommends the following test. — A little of the flour is mixed on a piece of common window glass or microscope slide, with sufficient water (at 45 C.) to float the flour particles. Spread the mixture out over the glass, and press another glass down upon it. When wheat flour is present, white spots will be seen, and if the glasses are slid upon each other the spots will pull out into threads, and the thicker and longer they are the more wheat flour there is present.

Ergot in Rye Flour

Boettger gives the following chemical test for ergot. — Heat 10 to 15 minutes with an equal quantity of ether, adding a few crystals of oxalic acid. When ergot is present a reddish color develops.

Another Method. — Bui. 51, Bureau of Chem.

Digest 20 grams of the suspected flour, with boiling alcohol, till no more color is extracted. Add 1 cc. of sulfuric acid (1: 3), and if ergot is present the solution will be colored red.

BREAD

ALUM

Moisten a piece of the bread with water, and then with a logwood solution (5 grams logwood digested in 100 cc. of alcohol). If alum is present the bread will become lavender blue in two or three hours. Pure bread would have a red-brown tint. To prove the presence of alum, the blue color must be permanent at the temperature of boiling water. (The logwood used in this test must be pure.)