XVII] DISTILLED LIQUORS 245 



tion to 100 cc. with 50% alcohol b}' volume. One cc. of this solution contains 

 0.0001 gram of furfural. 



(b) Furfural-free alcohol. — Prepare as directed in 9 (a). 



1 2 DETERMINATION. 



Dilute 10-20 cc. of the distillate, as prepared under 8, to 50 cc. with furfural- 

 free alcohol, 50% by volume. Add 2 cc. of colorless anilin and 0.5 cc. of hydro- 

 chloric acid (sp. gr. 1.125) and keep for 15 minutes in a water bath at about 15°C. 

 Prepare standards of known strength and blanks in the same way. The compari- 

 son standards found most convenient for use contain 0.00005, 0.0001, 0.00015, 0.0002, 

 0.00025 and 0.0003 gram of furfural. 



FUSEL OIL.-TENTATIVE. 



13 REAGENTS. 



(a) Purified carbon tetrachlorid. — Mix crude carbon tetrachlorid with one tenth 

 its volume of concentrated sulphuric acid, shake thoroughly at frequent intervals 

 and allow to stand overnight. Wash free of acid and impurities with tap water. 

 Remove the water, add an excess of sodium hydroxid solution and distil the carbon 

 tetrachlorid from it. 



(b) Oxidizing solution. — Disssolve 100 grams of potassium dichromate in 900 cc. 

 of water and add 100 cc. of concentrated sulphuric acid. 



14 DETERMINATION. 



(1) To 100 cc. of the sample add 20 cc. of N/2 sodium hydroxid and saponify the 

 mixture by boiling for an hour under a reflux condenser; or, (2) Mix 100 cc. of the 

 liquor with 20 cc. of N/2 sodium hydroxid, allow to stand overnight at room tem- 

 perature and distil directly. Connect the flask with a distillation apparatus, distil 

 90 cc, add 25 cc. of water and continue the distillation until an additional 25 cc. are 

 collected. 



Whenever aldehydes are present in excess of 15 parts per 100,000, add to the dis- 

 tillate 0.5 gram of meta-phenylendiamin hydrochlorid, reflux for an hour, distil 

 100 cc, add 25 cc. of water and continue the distillation until an additional 25 cc. 

 are collected. 



Approximately saturate the distillate with finely ground sodium chlorid and add 

 saturated sodium chlorid solution until the specific gravity is 1.10. 



Extract this salt solution 4 times with the purified carbon tetrachlorid, using 40, 

 30, 20 and 10 cc, respectively, and wash the carbon tetrachlorid 3 times with 50 

 cc. portions of saturated sodium chlorid solution, and twice with saturated sodium 

 sulphate solution. Then transfer the carbon tetrachlorid to a flask containing 50 

 cc. of the oxidizing solution and boil for 8 hours under a reflux condenser. 



Add 30 cc. of water and distil until only about 20 cc. remain; add 80 cc. of water 

 and again distil until 15-20 cc. are left. Neutralize the distillate to methyl orange, 

 and titrate with N/10 sodium hydroxid, using phenolphthalein as an indicator. 

 If the distillations have been properly conducted, the distillate will not show a 

 marked acid reaction to methyl orange. Should considerably more than 1 cc. of 

 N/10 alkali be consumed at this point, the result will be unreliable and the deter- 

 mination should be repeated. One cc. of N/10 sodium hydroxid is equivalent to 

 0.0088 gram of amyl alcohol. 



Rubber stoppers can be used in the saponification and first distillation, but 

 corks covered with tinfoil must be used in the oxidation and second distillation. 

 Corks and tinfoil must be renewed frequently. 



