FERMENTED AND DISTILLED LIQUORS. 89 



(a) SALICYLIC ACID. 



Treat about 75 cc of wine with sufficient basic lead acetate a to clarify, and filter 

 through a ribbed filter paper. Add from 5 to 10 cc of dilute sulphuric acid ( 1-3) , allow 

 the precipitated lead sulphate to subside, and decant about 50 cc of the supernatant 

 liquid into a separatory funnel. Extract with ether or chloroform and test for 

 salicylic acid as directed under Food preservatives (p. 108). The writer has obtained 

 much more satisfactory results by extracting after clarification as directed above, 

 than by extracting the wine directly with a mixture of ether and petroleum ether, 

 or by extracting the evaporated residue from the ether extract with petroleum ether. 

 In no case should the volume of wine extracted for the detection of salicylic acid 

 greatly exceed 50 cc. A similar reaction (with ferric chlorid) is said to be obtained 

 sometimes from wines which contain no salicylic acid when a large volume of the 

 wine is employed. b 



(b) BENZOIC ACID. 



Acidify about 100 cc of wine with dilute (1-3) sulphuric acid, extract with ether and 

 detect by Mohler's method, as described under Food preservatives (p. 109). 



The presence of benzoic acid may be confirmed by neutralizing the aqueous solu- 

 tion of the extracted benzoic acid with sodium hydroxid, evaporating to a very small 

 volume, and acidifying with sulphuric acid, when the presence of a large amount of 

 benzoic acid is indicated by the formation of a white flocculent precipitate. The 

 concentrated polution of the sodium salt may be further tested by adding a few drops 

 of phenolphthalein solution, and then a very dilute solution of sodium hydroxid 

 drop by drop, till an alkaline reaction is obtained, and a drop of a 0.5 per cent ferric 

 chlorid solution, which should decolorize the phenolphthalein, when ferric benzoate 

 is precipitated. The appearance of ferric benzoate is markedly different from that 

 of ferric hydroxid, in that it is almost white when viewed by transmitted light and 

 brown by reflected light, whereas ferric hydroxid has a brown color in both cases. 



(c) DETECTION OF SACCHARIN. 



Proceed as directed on page 109. 



(d) SUCROL OR DULCIN. 



(1) Morpurgo's method. 



Evaporate about 100 cc of wine to a sirupy consistency after the addition of about 

 5 grams of lead carbonate, and extract the residue several times with alcohol of 

 about 90 per cent; evaporate the alcoholic extract to dry ness; extract the residue 

 with ether, and allow the ether to evaporate spontaneously in a porcelain dish. 

 Now add 2 or 3 drops each of phenol and concentrated sulphuric acid and heat for 

 about five minutes on the water bath; cool; transfer to a test tube and pour ammo- 

 nia or sodium hydroxid over the surface with the least possible mixing. The 

 presence of dulcin is indicated by the formation of a blue zone at the plane of 

 contact. 



(2) Jorisson's method.* 



Suspend the residue from the ether extract obtained as directed above in about 5 

 cc of water; add from 2 to 4 cc of an approximately 10 per cent solution of mercuric 

 nitrate, and heat from 5 to 10 minutes on the water bath. In the presence of sucrol, 

 a violet blue color is formed, which is changed to a deep violet by the addition of 

 lead peroxid. 



See footnote on page 84. Xi-chr. anal. Chem., 18%, *">, 104. 



*>Medicus, Ztschr. anal. Chem., 1896, 85, 398. *Ib., G2. 



