Standard preparation— Prepare as directed in the Assay under Digitalis.

Assay preparation— Empty the contents of not less than 20 Capsules into a hard-glass, glass-stoppered container of not less than 50-mL capacity. Add a menstruum consisting of 4 volumes of alcohol and 1 volume of water so that the total volume of menstruum corresponds to 1 mL for each expected USP Digitalis Unit. Insert the stopper, the upper third of which is greased lightly with petrolatum. Shake the mixture at 25 ± 5 for 24 ± 2 hours by mechanical means, which continuously brings the solid material into fresh contact with the liquid phase. Immediately thereafter transfer to a centrifuge tube, centrifuge, and decant the supernatant tincture into a dry, hard-glass bottle having a tight closure. Preserve under refrigeration, and use within 30 days.

Pigeons, Preparation of test dilutions, Injection of test dilutions, and Calculation of potency— Proceed as directed in the Assay under Digitalis.