algarot

from The Century Dictionary.

• noun A violently purgative and emetic white powder, which falls when chlorid of antimony is dropped into water. It is a compound of chlorid and oxid of antimony.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Med.) A term used for the Powder of Algaroth, a white powder which is a compound of trichloride and trioxide of antimony. It was formerly used in medicine as an emetic, purgative, and diaphoretic.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A pale white emetic powder formerly used in alchemy, consisting of a compound of trichloride and trioxide of antimony.