DETECTION OF PRESERVATIVES. 61 



A portion of the residue extracted by chloroform, .supposed to con- 

 tain benzoic 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. 



About 50 cc of the sample are acidified with 5 cc of a 1-3 solution 

 of sulphuric acid and extracted in a separately funnel with a mixture 

 of equal parts of gasoline which distills below 60 and sulphuric ether. 

 On allowing the solvent to evaporate in a porcelain dish the presence 

 of saccharin in the residue may be detected by the taste. About 2 cc 

 of a saturated solution of sodium hydroxid are then added and the 

 dish heated till the water evaporates, and the sodium hydroxid fuses 

 quietly for from twenty to thirty minutes. 1 The saccharin is now 

 converted into salicylic acid. If the temperature is held at approx- 

 imately 250 during the fusion, the reaction is quantitative. The 

 fused mass is then allowed to cool, dissolved in about 50 cc of water 

 acidified with sulphuric acid, and tested for salicylic acid as directed 

 on page 59. This method presupposes that the wine contains no 

 salicylic acid. If that substance be also present, saccharin may be 

 separated by Gair's 2 method. The residue left by the evaporation of 

 ether is dissolved in 50 cc of dilute hydrochloric acid, sufficient bro- 

 min water added to impart a marked color to the liquid, the whole 

 thoroughly shaken and filtered. The salicylic acid is completely 

 precipitated as bromo-salicylic acid, while the filtrate may be made 

 strongly alkaline with sodium hydroxid, evaporated to dryness and 

 tested for saccharin as described above. 



DETECTION OF ABRASTOL. 



Fifty cc of the sample are made alkaline with a few drops of ammonia, 

 gently shaken for two minutes with 10 cc of amyl alcohol (ethyl alcohol 

 is added if an emulsion be formed). The amyl alcohol is decanted, 

 filtered if turbid, and evaporated to dryness. The residue is thor- 

 oughly moistened with 2 cc of a mixture of equal parts of strong nitric 

 acid and water, heated on the water bath until half of the water is 

 evaporated, and transferred to a test tube with the addition of 1 cc of 

 water. About 0.2 gram of ferrous sulphate is now added, and then 

 an excess of ammonia, drop by drop, with constant shaking. If the 

 resulting precipitate be of a reddish color, it is dissolved in a few 

 drops of sulphuric acid, and ferrous sulphate and ammonia are added 

 as before. As soon as a dark-colored or greenish precipitate has been 

 obtained, 5 cc of alcohol are added, the precipitate is dissolved in sul- 

 phuric acid, and the fluid is well shaken and filtered. In the absence 



1 Schmidt' s method. 2 Eev. intern, des f ala. , 1893. 



