What is "soda alum"

Soda \So"da\, n. [It., soda, in OIt., ashes used in making glass, fr. L. solida, fem. of solidus solid; solida having probably been a name of glasswort. See Solid.]

1. (Chem.)

   1. Sodium oxide or hydroxide.

   2. Popularly, sodium carbonate or bicarbonate. Sodium bicarbonate is also called baking soda

2. same as sodium, used in terms such as bicarbonate of soda.

3. same as soda water.

4. a non-alcoholic beverage, sweetened by various means, containing flavoring and supersaturated with carbon dioxide, so as to be effervescent when the container is opened; -- in different localities it is variously called also soda pop, pop, mineral water, and minerals. It has many variants. The sweetening agent may be natural, such as cane sugar or corn syrup, or artificial, such as saccharin or aspartame. The flavoring varies widely, popular variants being fruit or cola flavoring.

   Caustic soda, sodium hydroxide.

   Cooking soda, sodium bicarbonate. [Colloq.]

   Sal soda. See Sodium carbonate, under Sodium.

   Soda alum (Min.), a mineral consisting of the hydrous sulphate of alumina and soda.

   Soda ash, crude sodium carbonate; -- so called because formerly obtained from the ashes of sea plants and certain other plants, as saltwort ( Salsola). See under Sodium.

   Soda fountain, an apparatus for drawing soda water, fitted with delivery tube, faucets, etc.

   Soda lye, a lye consisting essentially of a solution of sodium hydroxide, used in soap making.

   Soda niter. See Nitratine.

   Soda salts, salts having sodium for the base; specifically, sodium sulphate or Glauber's salts.

   Soda waste, the waste material, consisting chiefly of calcium hydroxide and sulphide, which accumulates as a useless residue or side product in the ordinary Leblanc process of soda manufacture; -- called also alkali waste.

   Washing soda, sodium carbonate. [Colloq.]

n. A mineral consisting of the hydrous sulfate of alumina and soda.