72 PROVISIONAL MET BODS FOE ANALYSIS OF FOODS. 



100 C. Examine the residue for sugar and glycerol. The presence of capsicum may 

 be readily detected by taste. 



2. DETERMINATION OF GLYCEROL. 

 Proceed as directed on page 82. 



3. DETERMINATION OF ASH. 



Ignite the residue from 10 grams of the extract at a dull red heat. Examine the 

 ash for magnesia. Where the extract has been made with insufficient alcohol to 

 effect complete solution of the oil, the liquid is frequently clarified by filtration with 

 magnesia; in which case the latter substance may be detected in the ash. 



4. DETERMINATION OF SPECIFIC GRAVITY. 

 Determine the specific gravity as directed on page 82. 



5. DETERMINATION OF ALCOHOL. 



(a) Dilute 50 cc to 200 cc; pour mixture into dry Erlenmeyer flask containing 5 

 grams of light carbonate of magnesia. Stopper, shake well, and filter quickly through 

 a large, dry, plaited filter. Determine the alcohol in 150 cc of the filtrate, as directed 

 on page 82, multiplying the results so obtained by f to correct for the aliquot part 

 taken. 



( b) In the absence of appreciable quantities of solids or glycerol, calculate the alco- 

 hol approximately from the specific gravity of the extract, using Table II. 



6. DETECTION OF METHYL ALCOHOL. 



These methods consist in the conversion of the alcohols to aldehydes by the 

 method of Mulliken and Scudder, a the removal of acetaldehyde, and the detection 

 of formaldehyde when produced. 



Dilute a portion of the distillate obtained in the determination of alcohol (or, for 

 preliminary examination, dilute and filter the original extract) until the liquid con- 

 tains approximately 12 per cent of alcohol by weight. 



Oxidize 10 cc of the liquid in a test tube as follows: Wind copper wire 1 mm thick 

 upon a rod or pencil 7 to 8 mm thick in such a manner as to inclose the fixed end of 

 the wire and to form a close coil 3 to 3.5 cm long. Twist the two ends of the wire 

 into a stem 20 cm long and bend the stem at right angles about 6 cm from the free 

 end, or so that the coil may be plunged to the bottom of a test tube, preferably 

 about 16 mm wide and 16 cm long. Heat the coil in the upper or oxidizing flame 

 of a Bunsen burner to a red heat throughout. Plunge the heated coil to the bottom 

 of the test tube containing the diluted alcohol. Withdraw the coil after a second's 

 time and dip it in water. Repeat the operation from three to five times, or until the 

 film of copper oxide ceases to be reduced. Cool the liquid in the test tube mean- 

 while by immersion in water. Remove 10 drops of the liquid so oxidized to a small 

 porcelain capsule and reserve this for a separate test. 



(a) REMOVAL OF THE ACETALDEHYDE BY PRESCOTT's METHOD. b 



Add to the liquid remaining in the test tube 6 cc of a 3 per cent solution of 

 hydrogen peroxid or an equivalent amount. Mix and filter Into a porcelain dish. 

 After three minutes add 2 cc of a 10 per cent solution ot sodium thiosulphate. 

 After two or three minutes place the dish in a good white light and test for 

 formaldehyde. 



Test for formaldehyde. To the contents of the dish add 3 cc of a phloroglucin solu- 



s. p. Mnllikcii and H. Scudder, Amer. Chem. Jour., 1899, 21, 266. 

 b Pharmaceutical Archives, 1901, vol. 4, No. 6. 



