1002 FOODS AND FOOD ADULTERANTS. 
RICHARDS and PALMER. A volumetric method based upon the work of Gerland. A 
standard solution of tartrate of antimony and potassium is employed for the 
titration. A solution of acetate of ammonium is prepared for use as de- 
scribed below. In preparing this solution, saturate glacial acetic acid with 
stronger waterof ammonia. Exhausta weighed portion of the sample as usual 
with water, using such proportions to give approximately 0.3 to 0.9 gram 
tannin per 150 to 300 cc. Divide this solution into three or four aliquot 
parts. To one portion add the standard tartar emetic solution in slight ex- 
cess, and to a second add less of the solution than is required to precipitate 
the tannin. To each portion add 1 ce ammonium acetate solution per 25 ce 
taken. After allowing time for the precipitate to settle, test a drop of the 
clear liquid on a porcelain plate with a drop of sodium thiosulphate. An 
excess of antimony is indicated by an orange-yellow precipitate. The tests 
of the first two aliquot parts, more tartar emetic being added to the second 
if necessary, indicate approximately the volume of the antimony solution 
required to precipitate the tannin, and the remaining aliquot part or parts 
serve to determine this volume with accuracy. The volume of the standard 
solution taken xX .01— tannin as digallic acid. Ammonium acetate acts 
similarly to the chloride in Gerland’s method and prevents the precipita- 
tion of the gallic acid. Am. Jour. Sci., 16, 196 and 361; Allen’s Commercial 
Organic Analysis, Vol. m1, Pt. 1, 123; Prescott’s Organic Analysis, 471. 
RISLER-BEUNAT, H. A method based on the precipitation with stannous chloride. 
Extract 10 grams of tea thirty minutes with 500 ce water; wash the residue 
with about 500 cc boiling water; cool and complete the volume to 1 liter. 
Precipitate 100 ce of this extract with 100 ce stannous chloride solution 
containing 18 grams of this salt and 2 grams ammonium chloride per liter. 
Collect, wash, dry, and weigh the precipitate, then ignite with ammonium 
nitrate and again weigh. Calculate the resulting SnO, to SnO, and deduct 
this from the weight of the precipitate; the remainder is the weight of the 
tannin. Zeitsch. f. anal. Chem., 2, 287. 
ScHREINER, L. An apparatus for the absorption of tannin by hide powder. This 
apparatus is so arranged that the first portions of the solution, which always 
dissolve some albumin from the powder, collect in a small bulb placed below 
by reason of their greater density. Der Gerber, 14, 244. 
ScHULZE, F. A volumetric method employing a gelatin solution standardized by 
means of pure tannin disolved in a concentrated solution of chloride of am- 
monium. The gelatine is also dissolved in a concentrated solution of chlo- 
ride of ammonium. In the titration, the standard solution is added until 
the precipitate formed will settle within half a minute, leaving the super- 
natant liquid clear. Zeitsch. f. anal. Chem., 5, 455. 
Scumipt, E. A method employing a standard solution of lead acetate in dilute al- 
cohol. A measured volume of the solution to be assayed is warmed to 60° C. 
and titrated with the lead solution, using potassium iodide as an indica- 
tor. Bul. Soc. Chem. [2], 21, 256; also, Jsb. d. Chem., 1874, 1035. 
SacKNER. Sackner commenting on various methods for. tannin considers that of 
Lowenthal the most accurate. Wagner’s Jsb., 1861, 625. 
SIMPKIN, S.J. A volumetric method based on the oxidation of tannin by perman- 
ganate, and its precipitation by ammonium sulphate of copper. Chem. 
News, 32, 11; also Jsb. d. Chem. 
TERREIL. An improvement of Mittenzwey’s method. Terreil states that 0.1 gram 
pure tannic acid will absorb 20 ce oxygen in twenty-four hours. Ber. d. 
chem. Ges., 5, 362; also, Compt. Rend., 78, 690; also, Zeitsch. f. anal. Chem., 
13, 243. 
ViILLon, M. A method involving extensive calculations based on the specific gravi- 
ties of the original solution, the precipitant, and the solution after filtering 
off the precipitate. Lead acetate with sodium acetate is the precipitant em- 
