EXAMINATION OF MKAT PRODUCTS. 



57 



slight amount of protcid bodies is thrown down. If glucose has been 

 employed in its manufacture, howe\ er, a dense white precipitate sepa- 

 rates and after a time settles to the bottom of the liquid. 



DETECTION OF FOREIGN SEEDS. 



In addition to the forms of adulteration to which jellies are subject, 

 jams are sometimes manufactured from the exhausted fruit pulp left 

 after removing the juice for making jelly. When this is done resi- 

 dues from different fruits are sometimes mixed. Exhausted raspberry 

 or blackberry pulp ma} 7 be used in making "strawberry" jam and 

 vice versa. Some instances are reported of various small seeds, such 

 as timothy, clover, and alfalfa seed, having been used with jams made 

 from seedless pulp. 



With the aid of a small magnifying glass such forms of adulteration 

 may be detected, the observer familiarizing himself with the seeds of 

 the ordinary fruits. 



DETECTION OF PRESERVATIVES AND COLORS. 



With jellies and jams salicylic and benzoic acids are sometimes 

 employed. They may be detected by the methods given on pages 43 

 and 44. 



Artificial colors, usually coal-tar derivatives, are sometimes used 

 and may be detected as described on page 45. 



MEAT PRODUCTS. 



As in manj^ other classes of foods, certain questions important in the 

 judgment of meats require practical experience and close observation 

 rather than chemical training. This is especially true of meat prod- 

 ucts. The general appearance of the meat must largely guide the pur- 

 chaser. If, however, the meat has been treated with preservatives 

 and coloring matter its appearance is so changed as to deceive him. 

 The preservatives employed with meat products are boric acid, borax, 

 and sulphites. The methods for the detection of sulphites are not 

 suitable for household use. 



DETECTION OF BORIC ACID AND BORAX. 



To detect boric acid (if its sodium salt, borax, has been used the 

 same reaction will be obtained) about a tablespoonful of the chopped 

 meat is thoroughly macerated with a little hot water, pressed through 

 a bag, and 2 or 3 tablespoonfuls of the liquid placed in a sauce dish 

 with 15 or 20 drops of strong hydrochloric acid for each tablespoon- 

 fill. The liquid is then filtered through filter paper, and a piece of 

 turmeric paper dipped into it and dried near a lamp or stove. If boric 

 acid or borax were used for preserving the sample the turmeric paper 

 should be changed to a bright cherry-red color. If too much hydro- 

 chloric acid has been employed a dirty brownish-red color is obtained, 



