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 Kämmerer 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 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.

Salicylic Acid

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 evaporating to dryness and testing the residue with a drop of ferric chlorid solution. A deep violet coloration is produced if salicylic acid is present.

Benzoic Acid

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 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 100 cc. and saturate with hydrogen sulfid, filter, examine as follows:

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.

COLORING MATTER

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.

STARCH

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 starch is present. If there is only a little starch, it may be necessary to examine it under the