998 FOODS AND FOOD ADULTERANTS. 



stance. Many of the methods appear very simple, but in practice offer very 

 considerable difficulties, especially when gallic acid is present. 

 Commercial Organic Analysis, vol. in, Pt. 1, 109. 



ALLEN, A. H. This writer states that a German commission recommends, in per- 

 manganate titrations, the addition of the solution 1 cc at a time instead of 

 drop by drop. The results of the "1 cc method" differ considerably from 

 those obtained by the "drop method." The latter method was employed by 

 Neubauer and Oser in determining the reduction coefficients ; hence Allen 

 recommends it. At the reference cited, Procter points out the source of error 

 in the " 1 cc method." 

 Op. cit., page 116. 



ALLEN, A. H. A method for tea assay based on the precipitation of Tannin from a 

 hot solution by a standard solution of lead acetate, employing ammouiacal 

 ferricyanide in ascertaining the end reaction. 



Chem. News, 29, 189; also Allen's Commercial Organic Analysis, vol. in, Pt. 

 i, 123. 



BARBIERI, J. Essentially the method of Carpen4 (vide Carpene", A., Ding, polytec. 

 Journ., 216, 452) ; Ber. d. chem. Ges., 9, 78; also Zeitsch. f. anal. Chem., 16, 123. 



BECKER. A volumetric method in which a solution of tannin is run into a hot 

 solution of methyl-violet until the color is discharged. Zeitsch. f. anal. 

 Chem., 25, 133. 



BECKMA.N, E. A volumetric method employing a solution of anmionio-ferrous sul- 

 phate, crystallized sodium acetate, and acetic acid for the removal of the 

 tannin. The usual permanganate titrations are made before and after the 

 removal of the tannin. Zeitsch. f. anal. Chem., 25, 527. 



CARPENE, A. A volumetric method employing an ammoniacal solution of zinc acetate 

 for the precipitation of the tannin. The precipitate is collected, Avashed, 

 dissolved in dilute sulphuric acid, and titrated with permanganate of potas- 

 sium. Ding, polytec. Journ., 216, 452; Zeitsch. f. anal. Chem., 15, 112. 



CASALI, ADOLPHO. A volumetric method employing a standard nickel solution. A 

 paper soaked in ferric chloride solution containing ferrous sulphate is em- 

 ployed as an indicator. Annali di Chimi., 79, 65; also Chem. Ztg., 8, 1767; 

 also Zeitsch. f. anal. Chem., 24, 272. 



CECH. This author states that the presence of acetic acid, citric acid, tartaric acid, 

 malic acid, cane sugar, dextrin, gum, fat, caffeine, or urea does not interfere 

 in the estimation of tannin by permanganate, provided the solution is prop- 

 erly diluted. Zeitsch. f. anal. Chem., 7, 134. 



COLLJN AND BENOIST. A volumetric method based on the precipitation of tannin 

 by gelatin. A derivative of aniline added to the gelatin solution is used as 

 an indicator. The taimate absorbs the coloring matter and the solution be- 

 comes colorless when the precipitation is complete. A standard tannin solu- 

 tion is employed in making up the gelatin solution. Mon. Scien., March, 1888, 

 364 ; Journ. Soc. of Dyers, 4, 62. 



COMMAILLE. A volumetric method employing a standard -solution of iodic acid in 

 the presence of hydrocyanic acid. Zeitsch. f. anal. Chem., 3. 488. 



CONNCLER AND VON ScHKOEDER. An official report on the estimation of tannins, 

 containing recommendations in regard to methods of analysis, strength of 

 solutions, etc. Zeitsch. f. aiial. Chem., 25, 121. 



DARTON, N. H. Darton employed an amiuoiiio-.sulphate of copper solution for the 

 precipitation of tannin. Extract the tea first with cold, then with boiling 

 water. Treat the infusion with 'S< cc dilute sulphuric acid (1 part acid to 10 

 parts water ^ filter, render filtrate slightly alkaline with ammonia, and a.yain 

 filter. Treat 100 cc this solution with an equal volume of unimoiiiu sulphate 

 of -copper solution (1 per cent copper Hall ), collect the pn-ci|.jt;ite. Titrate 

 A knpwn volume of f.ho filtrate with purmttWganate for uow-t/aunins. Wash 



