86 METHODS OF ANALYSIS. 



paper shows an alkaline reaction. The result is expressed in terms of tartaric 

 acid. One cubic centimeter of tenth-normal sodium hydroxid is equivalent to 

 0.0075 gram tartaric acid. 



13. Volatile Acids. Provisional. 



Distil in a current of steam 50 cc of wine, to which a little tannin has been 

 added to prevent foaming. Heat the flask containing the sample until the 

 liquid boils, regulate the flame under it so that the volume remains constant, 

 and pass the steam through until 200 cc have been collected in the receiver. 

 Titrate the distillate with tenth-normal sodium hydroxid, using phenolphtha- 

 loin as indicator and express the result as acetic acid. 



One cubic centimeter of tenth-normal sodium hydroxid is equivalent to 0.006 

 gram acetic acid. 



14. Fixed Acids. Provisional. 



The amount of fixed acids is ascertained by subtracting 1.25 times the vola- 

 tile acids from the total acids expressed as tartaric. 



15. Tartaric Acid and Tartrates. Provisional, 

 (a) TOTAL TABTABIC ACID.<* 



To 100 cc of wine add 2 cc of glacial acetic acid, 3 drops of a 20 per cent 

 solution of potassium acetate, and 15 grams of powdered potassium chlorid, and 

 stir to hasten solution. Add 15 cc of 95 per cent alcohol and rub the side of 

 the beaker vigorously with a glass rod for about one minute to start crystal- 

 lization. Let stand at least fifteen hours at room temperature ; decant the 

 liquid from the separated acid potassium tartrate as rapidly as possible on a 

 gooch prepared with a very thin film of asbestos, transferring no more of the 

 precipitate to the crucible than necessary. Wash the precipitate and filter 

 three times with a small amount of a mixture of 15 grams of potassium chlorid, 

 20 cc of 95 per cent alcohol, and 100 cc of water, using not more than 20 cc of 

 the wash solution in all. Transfer the asbestos film and precipitate to the 

 beaker in which the precipitation took place, wash out the gooch with hot 

 water, add about 50 cc of hot water, heat to boiling, and titrate the hot solution 

 with tenth-normal sodium hydroxid, using delicate litmus tincture or litmus 

 paper as indicator. Increase the number of cubic centimeters of tenth-normal 

 alkali employed by 1.5 cc, on account of the solubility of the precipitate. One 

 cubic centimeter of tenth-normal alkali so consumed is equivalent to (unr.u 

 gram of tartaric acid. 



(b) CBEAM OF TARTAR. PROVISIONAL. 



Determine the alkalinity of the soluble ash as directed under "XVI. 

 Vim-gar." page 102. One cubic centimeter of tenth-normal alkali is equivalent 

 to 0.0188 gram of potassium bltartrate. 



(c) FREE TABTARIC ACID. PROVISIONAL. 



Add 25 cc of tenth-normal hydrochloric acid to the ash of 50 cc wine, boat 

 to Incipient boiling, and titrate with tenth-normal sodium or potassium 

 liydroxid, using litmus as indicator. Deduct the number of cubic centimeters 

 of alkali employed from 25 and multiply the remainder by 0.0075 to obtain the 



Halenke and Mdslinger, Zts. anal. Chern., 1895, 84: 263. 



