96 PROVISIONAL METHODS FOR ANALYSIS OF FOODS. 



obtained by placing a reflux condenser between the flask and absorption apparatus, 

 and heating the flask over a burner to the boiling point. Attach the other stopcock 

 tube to a soda-lime guard tube and pass a current of air through the apparatus. The 

 amount of carbon dioxid is ascertained by the increase in weight of the absorption 

 tube. 



16. DETECTION OF PRESERVATIVES. 



Proceed as directed on pages 88 and 107. 



(C) DISTILLED LIQUORS. 

 1. DETERMINATION OF SPECIFIC GRAVITY. 



Proceed as directed on page 82. Owing to the high alcohol content of distilled 

 liquors, care must be exercised that the temperature at which specific gravity is 

 determined be as nearly 15.6 C. as possible. 



2. DETERMINATION OF ALCOHOL. 



Measure 50 cc of the sample (at 15.6 C.) into a distilling flask, dilute with 100 cc 

 of water, and proceed as directed on page 82. The sample of distilled liquor taken 

 for the determination of alcohol is diluted more than in the case of wine because of 

 the errors attending distillates high in alcohol, errors due to evaporation and to 

 making up to volume at temperatures varying slightly from 15.6 C. All measure- 

 ments must be made at about that temperature. 



3. DETERMINATION OF EXTRACT. 

 Evaporate 100 cc to sirupy consistency and proceed as directed on page 83. 



4. DETERMINATION OF ASH. 

 Proceed as directed on page 83. 



5. DETERMINATION OF ACIDITY. 



Titrate 100 cc with decinormal sodium hydroxid using phenolphthalein as indi- 

 cator. The number of cubic centimeters employed is multiplied by 0.0060 for the 

 acidity expressed in grams of acetic acid per 100 cc. 



6. DETERMINATION OF SUGAR. 

 Proceed as directed on page 85. 



7. DETERMINATION OF FUSEL OIL. a 



The apparatus recommended for this determination is Brom well's modification of 

 Roese's fusel-oil apparatus. (See fig. 4.) 



The reagents required are fusel-free alcohol that has been prepared by fractional 

 distillation over caustic soda or caustic potash, rejecting the first one-fifth and the 

 last three-fifths of the distillate, and diluted to exactly 30 per cent by volume (sp. gr. 

 0.96541 at 15.6 C.), chloroform, freed from water and redistilled, and sulphuric 

 acid (sp. gr. 1.2857 at 15 C.). 



Distill slowly 200 cc of the sample under examination till about 175 cc have passed 

 over, allow the distilling flask to cool, add 25 cc of water, and distill again till the 

 total distillate measures 200 cc. Dilute the distillate to exactly 30 per cent by 

 volume b (sp. gr. 0.96541 at 15.6). 



Windisch, Arb. kais. Gesamt., Vol. V, p. 390. 



t> The following is an accurate method for diluting any given alcohol solution to a weaker solution 

 of definite percentage: Designate the volume percentage of the stronger alcohol by V and that of the 



