goa ball

from The Century Dictionary.

• noun A compound of drugs formed into a ball or an egg-shaped mass, and used as a remedy or preventive for fever, by scraping a little powder from the ball and dissolving it in water. These balls seem to be compounded of powerful drugs, and are commonly scented with musk. Also called Goa stone.
• noun 2. A hollow sphere of metal, often ornamented and of valuable material, made to contain a Goa ball (in sense 1).