FLAVORING EXTRACTS. 73 



tion made by dissolving 1 gram of phloroglucin and 20 grains of sodium hydroxid 

 in sufficient water to make 100 cc. A bright red coloration (not purple) indicates 

 the presence of methyl alcohol in the original sample. When too little hydrogen 

 peroxid is added an orange-yellow color will slowly appear. The hydrogen per- 

 oxid, if not fully destroyed, will give rise to a purple color of gradual formation. 

 The cherry or raspberry red produced as a result of methyl alcohol appears quickly 

 after the addition of the reagent, and fades quickly unless quite intense. The 

 intensity of the red color is in proportion to the quantity of methyl alcohol present. 

 If the wood alcohol be as much as 1 part to 20 of ethyl alcohol, its presence will be 

 revealed by this test. 



For comparison, test the ten drops reserved in the casserole for formaldehyde after 

 the addition of 10 cc of milk by Leach's modification of Hehner's test as directed 

 on page 108, using care not to boil the mixture. a 



(b) REMOVAL OF FORMALDEHYDE BY METHOD OF 8. P. MULLIKEN. b 



Oxidize 5 cc of the diluted alcohol as directed above. Add 1 cc of strong ammo- 

 nia to the oxidized liquid in a casserole and expel the acetaldehyde by boiling 

 gently over a direct flame until the vapor ceases to smell of ammonia. Add 2 to 3 

 drops of strong hydrochloric acid to set free the formaldehyde which has been 

 retained as hexamethyltetramin, and bring the liquid momentarily to a boil; cool 

 promptly by immersion of the casserole in water and test for formaldehyde by the 

 modified resorcin test, c as follows: 



Add to the liquid remaining 1 drop of a solution containing 1 part of resorcin in 200 

 parts of water, and pour the mixture cautiously into a test tube containing 3 cc of con- 

 centrated sulphuric acid, holding the tube in an inclined position in such a manner 

 that the two liquids shall not mix. Allow it to stand 3 minutes, then sway the tube 

 slowly from side to side in such a manner as to produce a gentle rotary motion of 

 the two layers. Persist in this operation, if necessary, for a minute or more, using 

 a piece of white paper for a background, and producing only a very gradual and par- 

 tial mixing of the acid and water. Nearly half of the acid should remain as a dis- 

 tinct unmixed layer at the end. When methyl alcohol is present, the shaking causes 

 the separation of more or less voluminous flocks of a very characteristic rose-red color. 

 The appearance of colored zones or flocks of other hues, even when tinged with red, 

 or of a rose-red solution without flocks, should never be considered proof of the pres- 

 ence of methyl alcohol. However, if the flocks are reddish-brown, or if the upper 

 layer has a pronounced red, it is often well to repeat the test. By this method for 

 the removal of acetaldehyde 10 per cent of methyl alcohol may be readily detected, 

 and an experienced operator may detect with certainty a less amount. d 



7. DETERMINATION OF LEMON OIL. 



(a) BY POLARIZATION. 



Polarize the extract without dilution in a 200-mm tube at a temperature of 20 C., 

 using the sugar scale. Divide the reading by 3.2 and, in the absence of other 

 optically active substances, the result will be the percentage of lemon oil by volume. e 



A small amount of cane sugar is occasionally present, being used to facilitate solu- 



Mulliken and Scudder advise against the use of the casein test owing to its extreme delicacy and 

 to tin- fact that minute amounts of formaldehyde may be produced by the oxidation of grain alcohol. 

 Anirr. ('hem. Jour., 1900, 24, III. 



b Personal communication from A. G. Woodman. 



Amer. Chem. Jour., 1899, 21, 'Jilt;. 



'In the examination of Other alcoholic liquids the substances interfering with the resorcin test, 

 together with methods for their removal, may be found by consulting the original article. Amer. 

 Chem. Jour., LS'J9, 21, 266. 



J.C. Mims finds pure oil of lemon to polarize as high as 35 in solutions of 10 per cent by volume. 



