Source : Webster's Revised Unabridged Dictionary (1913)

Saleratus \Sal`e*ra"tus\, n. [NL. sal a["e]ratus; -- so called
   because it is a source of fixed air (carbon dioxide). See
   {Sal}, and and {A["e]rated}.] (Old Chem.)
   A["e]rated salt; a white crystalline substance having an
   alkaline taste and reaction, consisting of sodium bicarbonate
   (see under {Sodium}.) It is largely used in cooking, with
   sour milk (lactic acid) or cream of tartar as a substitute
   for yeast. It is also an ingredient of most baking powders,
   and is used in the preparation of effervescing drinks.

Source : WordNet®

saleratus
     n : a white soluble compound (NaHCO3) used in effervescent
         drinks and in baking powders and as an antacid [syn: {bicarbonate
         of soda}, {sodium hydrogen carbonate}, {sodium
         bicarbonate}, {baking soda}]