Issued August 18, 1000. 



United States Department of Agriculture, 



BUREAU OF CHEMISTRY Circular No. 44. 

 H. W. WILEY, Chief of Bureau. 



APPARATUS FOR USE IN THE DETERMINATION OF VOLATILE ACIDS 

 IN WINES AND YINEGARS. 



By H. C. GORE, 

 Assistant Chemist, Division of Foods. 



Iii this modification of tlie Hortvet-Sellier apparatus a copper flask is sub- 

 stituted for the outer glass flask and a constant feed device for the flask has 

 been added ; there are also two changes of a minor nature consisting in a small 

 ridge blown in the inner flask to form a shoulder for the rubber gasket and the 

 elimination, as unnecessary, of the dropping funnel. The constant water feed 

 is operated by running the supply water through tube a (fig. 1), which passes 

 through tube &. The overflow passes through 6 and rises through tube c to the 

 small basin d, which is connected with the drain. Tube a is placed within tube 

 ?', because steam is so prevented from passing out through &. Distilled water 

 should be used which has been largely freed from carbon dioxid by washing it 

 from twenty to thirty minutes with a rapid stream of air. The water should 

 be admitted somewhat more rapidly than it is used. The rate of flow is con- 

 veniently regulated by comparing the rate of drip in the small sight tube e with 

 that from the condenser. Experiments with the, apparatus showed that when 

 tap water was supplied to the generator there was an error due to the presence 

 of carbon dioxid in the distillate, equal to about 0.3 cc of tenth-normal alkali in 

 100 cc, phenolphthalein being used as indicator. When ordinary distilled water 

 was used, the error was about 0.15 cc. When distilled water was employed from 

 which the greater portion of carbon dioxid had been removed by aerating, the 

 error was but 0.05 cc. The error is constant and may be subtracted from each 

 determination. 



The apparatus is operated as follows: 



Place 10 cc of the sample in the inner flask, which should have been removed 

 from the outer flask and be entirely cool. If the sample is noticeably charged 

 with carbon dioxid, pass through it a current of air for a few minutes by attach- 

 ing to the flask a stopper bearing a glass tube which is connected with suction. 



a J. Ind. Eng. Chem., 1909, 1 : 31. 



LCir. 44] 

 271109 



