12 



barium chlorid to determine the absence of chlorids and sulphates should be made 

 before the presence of malic acid be considered proved. 



XII. FLAVORING EXTRACTS. 

 Twenty-second Convention, 1905, Bui. 99, Cir. 26. 



On page 69 substitute Winton and Bailej^s modification of the Hess 

 and Frescott method for the determination of vanillin, coumarin, and 

 acetamid for the present gravimetric methods, i. e., "4. Detection and 

 Determination of Coumarin and Vanillin." 



4. DETECTION AND ESTIMATION OF VANILLIN, COUMARIN, AND ACETAXTLTD. 



(a) DETERMINATION OF VANILLIN, COUMARIN, AND ACETANILID (WINTON AND BAILEY'S 



MODIFICATION OF THE HESS AND PRESCOTT METHOD ). 

 J. Amer. Chem. Soc., 1899, 21: 256; 1902, 24: 1128; 1905, 27: 719. 



Weigh out 25 grams into a 200 cc beaker with marks showing volumes of 25 and 50 

 cc. Dilute to the 50 cc mark, and evaporate in a water bath to 25 cc at a tempera- 

 ture in the bath of not more than 70 C. Dilute a second time to 50 cc, and evaporate 

 to 25 cc. Add normal lead acetate solution drop by drop until no more precipitate 

 forms. Stir with a glass rod to facilitate flocculation of the precipitate, filter through 

 a moistened filter and wash three times with hot water, taking care that the total 

 filtrate does not measure more than 50 cc. Cool the filtrate and shake with 20 cc of 

 ether in a separatory funnel. Remove the ether to another separatory funnel and 

 repeat the shaking of the aqueous liquid with ether three times, using 15 cc each 

 time. Shake the combined ether solutions four or five times with 2 per cent ammonia, 

 using 10 cc for the first shaking and 5 cc for each subsequent shaking. Set aside the 

 combined ammoniacal solutions for the determination of vanillin. 



Wash the ether solution into a weighed dish and allow the ether to evaporate at 

 the room temperature. Dry in a desiccator, and weigh. Stir the residue for 

 fifteen minutes with 15 cc of petroleum ether (boiling point 30 to 40 C. ), and 

 decant the clear liquid into a beaker. Repeat the extraction with petroleum ether 

 two or three times. Allow the residue to stand in the air until apparently dry, 

 completing the drying in a desiccator. Weigh, and deduct the weight from the 

 weight of the residue obtained after the ether evaporation, thus obtaining the weight 

 of the coumarin. This residue, if acetanilid, should have a melting point of about 

 112 C., and respond to Ritsert's qualitative tests. 



Allow the petroleum ether extract to evaporate at room temperature. If it is pure 

 coumarin, it should have a melting point within a few degrees of 67 C., and respond 

 to Leach's test. 



Slightly acidulate the ammoniacal solution, reserved for vanillin, with 10 per 

 cent hydrochloric acid. Cool, and shake out in a separatory funnel with four por- 

 tions of ether, as described for the first ether extraction. Evaporate the ether at 

 room temperature in a weighed platinum dish, dry over sulphuric acid, and weigh. 



If acetanilid has not been previously detected, this residue should be pure vanil- 

 lin, with a melting point within a few degrees of 80 C. 



If acetanilid has been detected, dissolve the residue in 15 cc of 10 per cent 

 ammonia, and shake out twice with an equal volume of ether. Evaporate the ether 

 solution at room temperature, dry in a desiccator, and w T eigh. Deduct this weight 

 from the previous weight, thus obtaining the weight of pure vanillin. The total 

 weight of the acetanilid is obtained by adding the weight of this last extract to that 

 of the residue previously obtained, and identified as acetanilid. 



