“If 0.5 gm. be shaken with 5 c.c. of alcohol and 1 c.c. of the filtrate be diluted with 15 c.c. of water, neither a turbidity nor a flocculent precipitate should appear....”

When this test was applied to the three specimens under examination, the Merck and Heyden specimens complied, while the Research Council specimen did not comply, with this requirement.

Method 1.—About 1 gm. of bismuth tri­brom­phenate was placed in a flask, 20 c.c. of 95 per cent. alcohol added and shaken for fifteen minutes, after which it was filtered by suction through a Gooch filter into an Erlenmeyer flask. The flask was rinsed with 10 c.c. of alcohol and finally the filter was washed with 10 c.c. of alcohol, 25 c.c. of tenth-normal sodium hydroxid solution were added to the alcoholic filtrate (which was nearly but not perfectly clear) containing the tri­brom­phenol, and the residual alkali titrated with tenth-normal hydrochloric acid.

The number of cubic centimeters of tenth-normal alkali consumed multiplied by 0.331 gave the weight of tri­brom­phenol (Table 3).

TABLE 3.—DETERMINATION OF FREE TRIBROMPHENOL

Gm. of
Salt Taken		Gm. Tribromphenol
Calculated from
Theoretical
Factor		Per Cent.
Free
Tribromphenol
Research Council Spec.2.33510.380616.31
Merck & Co.0.79800.0364 4.56
Heyden Chemical Works1.94600.0132 0.68

Method 2.—About 2 gm. of bismuth tri­brom­phenate were placed in a glass stoppered Erlenmeyer flask, 100 c.c. of alcohol were measured in and shaken during one-half hour and allowed to stand over night. Fifty c.c. of the supernatant liquid were then removed by means of a pipet, a slight excess of tenth-normal sodium hydroxid added and the residual alkali titrated with tenth-normal HCl.

Table 4 gives results obtained.

TABLE 4.—PER CENT. OF TRIBROMPHENOL BY METHOD 2

Gm. of
Salt Taken		Gm. Tribromphenol
Calculated from
Theoretical
Factor		Per Cent.
Free
Tribromphenol
Research Council Spec.2.07120.390518.85
Merck & Co.1.94170.0760 3.92
Heyden Chemical Works2.04400.0198 0.97