1410 FOODS AND FOOD ADULTEBANTS. 



A portion of the residue, supposed to contain benzole acid, may 

 also be treated with dilute sodium hydroxid and sodium amalgam, when 

 the presence of benzoic acid will- be detected by the smell of bitter 



almond oil. 



DETECTION OF SACCHARIN. 



Extract with ether as directed under salicylic acid. Allow the ether 

 extract to evaporate to dryness. Saccharin may be detected in the 

 residue by the taste. Also add from 1 to 2 grams of sodium hydroxid, 

 and fuse at about 250 for fifteen minutes. The saccharin is thus com- 

 pletely converted into salicylic acid, which may be detected as directed 



above. 



DETECTION OF SULPHITES. 



The first portion of distillate obtained in the detection of benzoic 

 acid is received in a solution of iodin, boiled, and barium chlorid added 

 to precipitate the sulphuric acid formed by the oxidation of sulphur- 

 ous acid. The formation of more than a trace of barium sulphate may 

 be regarded as proof that the original sample was preserved with 

 sulphite. 



According to Kammerer a sample of the meat under examination 

 should be placed on paper impregnated with potassium iodate mois- 

 tened with dilute sulphuric acid (1 :8) free from nitric oxid. In the pres- 

 ence of sulphurous acid a deep blue color is immediately produced. A 

 trace of blue may be formed after some time with meat that is nt 

 entirely fresh. This method is of little value, however, in the examina- 

 tion of canned meat, since it is not applicable in the presence of either 

 nitrates or chlorids. The microscope is also of value in the detection of 

 sulphites, since characteristic crystals of sodium and calcium sulphate 

 (owing to the oxidation of the original sulphite) may often be detected. 



DETECTION OF COLORING MATTER. 



Sausages and other preparations in which chopped meat is employed 

 rapidly become discolored on exposure to the air. This change does 

 not take place to a marked extent with meat that has been cured in a 

 pickle containing saltpeter. With fresh chopped meat, and sometimes 

 with corned meat, especially that cured without saltpeter, coloring 

 matter is sometimes added to prevent the change of color which would 

 naturally take place. Aniline dyes and cochineal carmin are ordinarily 

 employed for this purpose, though in some instances vegetable colors 

 have been detected in the form of lakes. The coloring matter may 

 often be extracted by heating for some time with 50 per cent alcohol, 

 50 per cent glycerol slightly acidified, a mixture of alcohol and gly- 

 cerol, a ammonium hydroxid, or a 5 per cent aqueous solution of sodium 

 salicylate. b 



a Klinger and Bujard, Ztschr. ang. Chem., 1891, 515. 

 b Spaeth, Pharm. Centraih., 1897, 38, 884. 



