Packaging and storage—
Preserve in tight containers.
Labeling—
If an indicator has been added, the name and color change of such indicator are stated on the container label. The container label indicates also the mesh size in terms of standard-mesh sieve sizes (see
Powder Fineness 
811
).
Identification—
A:
Place a granule of it on a piece of moistened red litmus paper: the paper turns blue immediately.
B:
A 1 in 10 solution of it in 6 N acetic acid responds to the tests for
Barium 191 and for
Calcium 191, and it may respond also to the flame test for
Potassium 191.
Particle size 786—
Screen 100 g for 5 minutes as directed under
Method I, using a mechanical shaker. It passes completely through a No. 2 standard-mesh sieve, and not more than 2.0% passes through a No. 40 standard-mesh sieve. Not more than 7.0% is retained on the coarse-mesh sieve, and not more than 15.0% passes through the fine-mesh sieve designated on the label.
Loss on drying 731—
Weigh accurately, in a tared weighing bottle, about 10 g, and dry at 105
for 2 hours: it loses between 11.0% and 16.0% of its weight.
Hardness—
Screen 200 g on a mechanical sieve shaker (see
Particle Size Distribution Estimation by Analytical Sieving 786) having a frequency of oscillation of 285 ± 3 cycles per minute, for 3 minutes, to remove granules coarser than 4-mesh and finer than 8-mesh. Weigh 50 g of the granules retained on the screen, and place them in a hardness pan of the following description: the hardness pan has a diameter of 200 mm and a concave brass bottom, and the bottom of the pan is 7.9 mm thick at the circumference and 3.2 mm thick at the center and has an inside spherical radius of curvature of 109 cm. Add 15 steel balls of 7.9-mm diameter, and shake on a mechanical sieve shaker for 30 minutes. Remove the steel balls, brush the contents of the hardness pan onto a sieve of the fine-mesh size designated on the label, shake for 3 minutes on the mechanical sieve shaker, and weigh: the percentage of Barium Hydroxide Lime retained on the screen is not less than 75.0, and represents the hardness.
Carbon dioxide absorbency—
Fill the lower transverse section of a U-shaped drying tube of about 15-mm internal diameter and 15-cm height with loosely packed glass wool. Place in one arm of the tube about 5 g of anhydrous calcium chloride, and accurately weigh the tube and the contents. Into the other arm of the tube place 9.5 g to 10.5 g of Barium Hydroxide Lime, and again weigh accurately. Insert stoppers in the open arms of the U-tube, and connect the side tube of the arm filled with Barium Hydroxide Lime to a calcium chloride drying tube, which in turn is connected to a suitable source of supply of carbon dioxide. Pass the carbon dioxide through the U-tube at a rate of 75 mL per minute for 20 minutes, accurately timed. Disconnect the U-tube, cool to room temperature, remove the stoppers, and weigh: the increase in weight is not less than 19.0% of the weight of Barium Hydroxide Lime used for the test.
