bleaching powder

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A powder containing calcium chloride and calcium hypochlorite, used in solution as a bleach.

from The Century Dictionary.

• noun A powder made by exposing slaked lime to the action of chlorin; chlorid of lime.

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

• noun A white powder, a mixture of calcium hypochlorite and calcium chloride, prepared by the action of chlorine on calcium hydroxide, used as a strong bleaching agent and disinfectant.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a white powder comprised of calcium hydroxide and chloride and hypochlorite and used to bleach and/or disinfect