What is "baking powder"

Powder \Pow"der\, n. [OE. poudre, pouldre, F. poudre, OF. also poldre, puldre, L. pulvis, pulveris: cf. pollen fine flour, mill dust, E. pollen. Cf. Polverine, Pulverize.]

1. The fine particles to which any dry substance is reduced by pounding, grinding, or triturating, or into which it falls by decay; dust.

   Grind their bones to powder small.
   --Shak.

2. An explosive mixture used in gunnery, blasting, etc.; gunpowder. See Gunpowder.

   Atlas powder, Baking powder, etc. See under Atlas, Baking, etc.

   Powder down (Zo["o]l.), the peculiar dust, or exfoliation, of powder-down feathers.

   Powder-down feather (Zo["o]l.), one of a peculiar kind of modified feathers which sometimes form patches on certain parts of some birds. They have a greasy texture and a scaly exfoliation.

   Powder-down patch (Zo["o]l.), a tuft or patch of powder-down feathers.

   Powder hose, a tube of strong linen, about an inch in diameter, filled with powder and used in firing mines.
   --Farrow.

   Powder hoy (Naut.), a vessel specially fitted to carry powder for the supply of war ships. They are usually painted red and carry a red flag.

   Powder magazine, or Powder room. See Magazine, 2.

   Powder mine, a mine exploded by gunpowder. See Mine.

   Powder monkey (Naut.), a boy formerly employed on war vessels to carry powder; a powder boy.

   Powder post. See Dry rot, under Dry.

   Powder puff. See Puff, n.

Baking \Bak"ing\, n.

1. The act or process of cooking in an oven, or of drying and hardening by heat or cold.

2. The quantity baked at once; a batch; as, a baking of bread.

   Baking powder, a substitute for yeast, usually consisting of an acid, a carbonate, and a little farinaceous matter.

n. a dry leavening agent used in baking; a mixture of baking soda, an acid (often cream of tartar) and starch to keep it dry; when wetted, carbon dioxide is released

n. any of various powdered mixtures used in baking as a substitute for yeast

Baking powder is a dry chemical leavening agent, a mixture of a carbonate or bicarbonate and a weak acid, and is used for increasing the volume and lightening the texture of baked goods. Baking powder works by releasing carbon dioxide gas into a batter or dough through an acid-base reaction, causing bubbles in the wet mixture to expand and thus leavening the mixture. It is used instead of yeast for end-products where fermentation flavors would be undesirable or where the batter lacks the elastic structure to hold gas bubbles for more than a few minutes, or to speed the production. Because carbon dioxide is released at a faster rate through the acid-base reaction than through fermentation, breads made by chemical leavening are called quick breads.