Maumene. A method for the estimation of tannin in wines. The tannin is precipitated by barium hydrate, and the precipitate after washing is dissolved in dilute sulphuric acid and titrated with permanganate. Bul. Soc. Chim. [2], 22, 41;" Jsb. d. Chem., 1874,1046.

Mittenzwey. A method depending upon the absorption of oxygen by tannin. A portion of the substance is shaken in a graduated tube with a 30 per cent solution of potassium hydroxide. After standing twenty-four hours the tube is opened under water and the absorption noted. Journ. f. prakt. Chem., 91, 81.

Monier E. Monier was the first to propose the use of permanganate of potassium in tannin estimations. He did not publish a definite method. Compt. Rend., 46, 577; Ding. poly. Journ., 118,209.

Moullade, A. A modification of Jean's method for the estimation of tannin, employing iodine with sodium bicarbonate. Carbon bisulphide is used as an indicator. Journ. de Pharm. et de Chim. [5], 22, 153.

Muller, G. An improvement in Davy's method similar to that of Lehman. Wagner's Jsb., 1858, 510; Zeitsch. f. anal. Chem., 5, 5.

Ostermayer. This chemist substitutes magenta for the rose aniline in Wagner's method. Chem. News, 40, 181.

Pavesi and Rotondi. A modification of Fleck's method, employing a solution of copper acetate with ammonium carbonate. The authors consider the precipitate to have the formula C14H4Cu2(NH4)2O9 + H2 O. Gazz. Chim. Ital., 1874, 194; also Ber. d. chem. Ges., 1874, 590.

Persoz, J. Persoz estimated the tannin, employing stannous chloride, by comparing the volume of the precipitate after setting aside from ten to twelve hours, with that obtained under the same conditions as to volume and time with a standard tannin solution. Traite de 1' Impression des Tissus, I, 282.

Perret, M. Perret employs an albumin solution as a precipitant of tannin, then removes the excess of albumin. The tannin is calculated from weight of the dried precipitate. Bul. Soc. Chim. de Paris, 41, 32; Zeitsch. f. anal. Chem., 24, 273.

Pribram. Based on the precipitation of tannin by lead acetate. The organic matter contained in the precipitate is termed "total astringent matter." Jsb. d. Chem., (1866) 17, 821; Vierteljahresber. f. Chem., 15, 520.

Procter, H. R. A modification of Lowenthal's method (see page 890, this report). A valuable improvement comprised in this modification is the use of powdered kaolin to facilitate the filtration after the addition of the gelatin. Journ. Soc. Chem. Ind., 3, 82.

Procter, H. R. The same as Hammer's method, except that hide powder is used instead of the animal skin. Allen's Commercial Organic Analysis, Vol. III, Pt. 1, 119.

Procter, H. R. A criticism of Gantter's method. Procter finds that the amount of permanganate consumed is materially influenced by the excess in which it is added and by the time of boiling. He concludes that by a rigid scheme of operation the new method might give concordant results, but at best such results could have but a comparative value. Journ. Soc. Chem. Ind., 9, 260; Journ. Franklin Inst., 129, 421.

Prud'homme. A volumetric method employing a standard solution of calcium hypochlorite with an aniline color (methyl-orange) as an indicator. The color is discharged in the presence of unprecipitated tannin. Bul. Soc. Chem. [2], 21, 169; Jsb. d. Chem., 1874. 1034.

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 described below. In preparing this solution, saturate glacial acetic acid with stronger water of ammonia. Exhaust a 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 excess, and to a second add less of the solution than is required to precipitate the tannin. To each portion add 1 cc ammonium acetate solution per 25 cc 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 X .01 = tannin as digallic acid. Ammonium acetate acts similarly to the chloride in Gerland's method and prevents the precipitation of the gallic acid. Am. Jour. Sci., 16, 196 and 361; Allen's Commercial Organic Analysis, Vol. in, 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 cc water; wash the residue with about 500 cc boiling water; cool and complete the volume to 1 liter. Precipitate 100 cc of this extract with 100 cc 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 SnO2 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 ammonium. The gelatine is also dissolved in a concentrated solution of chloride of ammonium. In the titration, the standard solution is added until the precipitate formed will settle within half a minute, leaving the supernatant liquid clear. Zeitsch. f. anal. Chem., 5, 455.

Schmidt, E. A method employing a standard solution of lead acetate in dilute alcohol. A measured volume of the solution to be assayed is warmed to60°C. and titrated with the lead solution, using potassium iodide as an indicator. 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 permanganate, 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 putt tannic acid will absorb 20 cc oxygen in twenty-four hours. Ber. d. chem. Ges., 5, 362; also, Compt. Rend., 78, 690; also, Zeitsch. f. anal. Chem., 13, 243.

Villon, M. A method involving extensive calculations based on the specific gravities of the original solution, the precipitant, and the solution after filtering off the precipitate. Lead acetate with sodium acetate is the precipitant employed. In the original article several of the constants for different tannins are given. Chem. News, 55, 168.

Wagner. A volumetric method, employing a standard solution of cinchonine colored with rosanaline and acidulated with sulphuric acid. Zeitsch. f. anal. Chem., 5, 1.

Warrington. A volumetric method depending upon the direct precipitation of tannin by gelatin. A filter tube for testing is prepared by loosely introducing a piece of sponge into the end of a small tube. In filtering off a test sample immerse the sponge in the solution, and the clear liquid will rise into the tube. Test this filtrate with gelatin. Phil. Mag., 31, 150; also Journ. Sci., 1848, 6, 112.

Weiss. Illustrations of apparatus for the continuous extraction of barks, etc. Zeitsch. f. anal. Chem., 28, 114.

Wildenstein, R. A colorimetric method, employing strips of filter paper of various shades and comparing them with strips of similar paper after dipping them into the infusion which had been previously treated with an iron salt. Zeitsch. f. anal. Chem., 2, 137.

Wolff, E. A method for the estimation of tannin in teas, employing copper acetate as a precipitant. The precipitate, after washing with boiling water, is dried and ignited, moistening with nitric acid. Weight obtained X 1.304 = gallo-tannin. Krit. Blaett., 44, 167; Zeitsch. f. anal. Chem., 1, 103.