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. 11, Pt. 1, 109. 
ALLEN, A. H. This writer states that a German commission recommends, in per- 
manganate titrations, the addition of the solution 1 ce 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 ec 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 ammoniacal 
ferricyanide in ascertaining the end reaction. 
Chem. News, 29, 189; also Allen’s Commercial Organic Analysis, vol. 111, Pt. 
1, 123. 
BARBIERI, J. Essentially the method of Carpené (vide Carpené, 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. 
BECKMAN, E. A volumetric method employing a solution of ammonio-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, washed, 
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. 
Crecn. 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. 
COLLIN 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 tannate 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 SCHROEDER. An official report on the estimation of tannins, 
containing recommendations in regard to methods of analysis, strength of 
solutions,etc. Zeitsch. f. anal. Chem., 25, 121. 
Darton, N. H. Darton employed an ammonio-sulphate of copper solution for the 
precipitation of tannin. Extract the tea first with cold, then with boiling 
water. Treat the infusion with 25 ce dilute sulphuric acid (1 part acid to 10 
parts water), filter, render filtrate slightly alkaline with ammonia, and again 
filter. Treat 100 ce this solution with an equal volume of ammonia sulphate 
of copper solution (1} per cent copper salt), collect the precipitate. Titrate 
a known volume of the filtrate with permanganate for non-tannins. Wash | 
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