80 C. U. C. P. ALUMNI JOURNAL May, 1918 



Conducted by Prof, George C. Diekman, 



Alcohol Determination 



The addition of sodium fluoride to solutions containing not less than i to 

 2% of alcohol, will result in the "salting out" of the latter, according to C. J. 

 Haines and J. W. Marden, in /. Ind. Eng. Cheni., igij, g, 1 126-7. I^ the 

 alcoholic content of the liquid exceeds 50%, 5 mils of the liquid, diluted to 10 

 mils with water, are employed, lesser strengths permit the use of 10 mils of the 

 original liquid. The liquid is placed in a centrifugal tube, graduated in 0,01 mil, 

 and sufficient sodium or potassium fluoride added, to cause the volume of the 

 liquid to inrease to 13 mils. In order to render the alcoholic layer more visible, 

 a very small amount of malachite green is added. The tube is then closed, 

 shaken vigorously for from 2 to 3 minutes, allowed to cool, and the contents 

 then centrifuged. An addition of 0,15 mil must be made to the reading in order 

 to compensate for incomplete separation and traces of alcohol which will continue 

 to adhere to the side of the tube. The temperature at which the operation 

 is carried out should be as near to 15.6° C. as possible, a correction of 0,001 mil 

 must be made for each degree by which the temperature deviates from this 

 temperature. The authors state that the method is applicable to tinctures, spirits, 

 wines, beer, cider, etc., and that it yields results within 0,40% of those obtained 

 by the distillation and specific gravity methods. The presence of iodine, as in 

 case of the tincture, seems to exert little or no effect upon the volume of alcohol 

 separated. 



Tannic and Gallic Acids 



M. Mito, in /. Chem. Ind. Tokyo, 1917, 20, gives an account of the 

 preparation of tannic and gallic acids and pyrogallol. The following is taken 

 from his report : Japanese gall nuts were extracted with water in four successive 

 treatments, at 20° to 30° C, and the residue expressed. In such manner a 13% 

 solution of tannic acid was obtained, and this yielded 82% of the theoretical 

 quantity. Tannic acid was obtained by concentrating the solution, at proper 

 temperature, to 20% strength, extracting with half its volume of ether, and 

 vaporizing the ether extract thus obtained. A yield of 75% of the tannin in the 

 aqueous extract was obtained. The residual solution, after extracting the tannin 

 was treated for removal of gallic acid, by first concentrating to 20% strength, 

 and then treating with sulphuric acid, 15% to 20% by volume, (specific gravity 

 1.84). The precipitated black mass was dissolved in water, and after being 

 decolorized by treatment with animal charcoal, was recrystallized. Pyrogallol 

 was produced by heating crude gallic acid, with about 3 times its own volume 

 of water, in an autoclave at 210* C. 



Tannin Content of Trees 



H. B. Benson and F. M. Jones, in /. Ind. Eng. Chcm., IQT7, give an 

 interesting account of investigations made with a view of determining the tannin 



