Part 84

=423. Pancreas Peptone.=—The filtrate obtained as described above, by treating the portion of the material insoluble in alcohol with warm water, contains in addition to the albumose and gelatin the whole of the pancreas peptone which may be present. To separate this peptone, 100 cubic centimeters of the aqueous solution are evaporated in a porcelain dish until the volume does not exceed ten cubic centimeters. When cool, at least 100 cubic centimeters of a saturated cooled solution of ammonium sulfate solution are added, the mixture thoroughly stirred, the precipitate collected upon a filter and washed with a cold saturated solution of ammonium sulfate. The contents of the filter are dissolved in boiling water, the filter thoroughly washed and the filtrate and washings evaporated in a porcelain dish with the addition of barium carbonate until, on the addition of new quantities of barium carbonate, no further trace of ammonia can be discovered. The residue is extracted with water, the barium sulfate and carbonate present separated by filtration, well washed and the nitrogen determined in the evaporated filtrate and washings in the usual way and multiplied by 6.25 to determine the quantity of pancreas peptone.

=424. Albumose Peptone.=—A part of the albumose peptone which may be present is determined in conjunction with the other bodies mentioned above. The chief quantity is found in the solution of the residue insoluble in alcohol in the following manner:

Fifty cubic centimeters of the solution of this residue in hot water are mixed with an equal volume of dilute sulfuric acid, one volume of acid to three of water, in the cold, and a solution of sodium phosphotungstate added until it produces no further precipitate. The precipitate is washed with dilute sulfuric acid and the nitrogen determined therein. The nitrogen thus found is derived from the albumose, pancreas peptone and gelatin. The quantity of nitrogen in the pancreas peptone and gelatin, as above described, is subtracted from the total quantity found in the phosphotungstic acid precipitated, and the remainder represents the nitrogen due to the albumose.

=425. Nitrogen in the Form of Flesh Bases Insoluble in Alcohol.=—This is determined by subtracting the quantity of nitrogen, determined by the phosphotungstic acid method already described, from the total quantity of nitrogen found in the precipitate insoluble in alcohol and soluble in water.

AUTHORITIES CITED IN PART FIFTH.

Watts’ Dictionary of Chemistry, new edition, Vol. 4, p. 327.

Vid. op. cit. supra, p. 330.

Barbieri, Journal für praktische Chemie, neue Folge Band 18, S. 114.

Vid. op. cit. 1, p. 339.

Bulletin No. 49, Kansas Experiment Station, May, 1895.

This work, Vol. 2, p. 208.

Vid. op. cit. supra, Vol. 1, p. 570.

Wiley, American Chemical Journal, Vol. 6, No. 5, p. 289.

Obermayer, Chemiker-Zeitung Repertorium, Oct. 1889, S. 269.

Hoppe-Seyler, Handbuch der physiologisch- und pathologisch-chemischen Analyse, S. 269.

Wiley, American Chemical Journal, Vol. 6, p. 289.

Dragendorff’s Plant Analysis, p. 55.

This work, Vol. 2, pp. 192 et seq.

Chemiker-Zeitung, Band 20, S. 151.

This work, Vol. 2, p. 207.

Landwirtschaftlichen Versuchs-Stationen, Band 17, S. 321: Zeitschrift für analytische Chemie, Band 14, S. 380.

Vid. op. cit. 12, p. 245.

Landwirtschaftlichen Versuchs-Stationen, Band 16, S. 61.

Berichte der deutschen chemischen Gesellschaft, Band 10, Ss. 85, 199; Band 16, S. 312: Chemiker-Zeitung, Band 20, S. 145.

Zeitschrift für analytische Chemie, Band 22, S. 325.

Richardson and Crampton, Berichte der deutschen chemischen Gesellschaft, Band 19, S. 1180.

Maxwell, American Chemical Journal, Vol. 13, p. 470.

Vid. op. cit. supra, Vol. 15, p. 185.