48 FOOD ADULTEKATION AND METHODS FOE DETECTION. 



liquid itself. A drop of household ammonia changes this red color to 

 a dark green, almost black. If too much hydrochloric acid is used a 

 dirty brownish color is produced. 



DETECTION OF CARAMEL. 



A solution of caramel is used to color many substances, such as vin- 

 egar and some distilled liquors. To detect it two test tubes or small 

 bottles of about equal size and shape should be employed and an equal 

 amount (2 or 3 tablespoonf uls or more) of the suspected sample placed 

 in each. To one of these bottles is added a teaspoonful of fullers' 

 earth, the sample shaken vigorously for two or three minutes and 

 then filtered through filter paper, the first portion of the filtered liquid 

 being returned to the filter paper and the sample finally collected into 

 the test tube or bottle in which it was originall} T placed, or a similar 

 one. The filtered liquid is now compared with the untreated sample. 

 If it is markedly lighter in color it may be taken for granted that the 

 color of the liquid is due to caramel, which is largely removed by 

 fullers' earth. In applying this test, however, it must be borne in 

 mind that caramel occurs naturally in malt vinegar, being formed in 

 the preparation of the malt. It is evident that the tests require prac- 

 tice and experience before they can be successfully performed. The 

 housewife can use them, but must repeat them frequent^ in order to 

 become proficient in their use. 



EXAMINATION OF CERTAIN CLASSES OF FOODS. 

 CANNED VEGETABLES. 



As before stated, canned vegetables are relatively free from adul- 

 teration by means of foreign subrtances. The different grades of 

 products may with care be readily detected by the general appearance 

 of the sample. The purchaser is, of course, at the disadvantage of 

 not being able to see the product until the can is opened. By a study 

 of the different brands available in the vicinity, however, he can read- 

 ily select those which are preferable. As stated in an earlier part of 

 the bulletin, canned tomatoes sometimes contain an artificial coloring 

 matter, which may be detected as described on page 45. 



Canned sweet corn is sometimes sweetened with saccharin, which 

 may be detected as described on page 45. 



It is believed that as a rule canned vegetables are free from pre- 

 servatives, although some instances of chemical preservation have 

 recently been reported in North Dakota, and some imported tomatoes 

 have been found by this Bureau to be artificially preserved. The 

 presence of copper, often used for the artificial greening of imported 

 canned peas, beans, spinach, etc., may be detected as described on 

 page 46. 



