What is "wine stone"

Tartar \Tar"tar\, n. [F. tartre (cf. Pr. tartari, Sp., Pg., & It. tartaro, LL. tartarum, LGr. ?); perhaps of Arabic origin.]

1. (Chem.) A reddish crust or sediment in wine casks, consisting essentially of crude cream of tartar, and used in marking pure cream of tartar, tartaric acid, potassium carbonate, black flux, etc., and, in dyeing, as a mordant for woolen goods; -- called also argol, wine stone, etc.

2. A correction which often incrusts the teeth, consisting of salivary mucus, animal matter, and phosphate of lime.

   Cream of tartar. (Chem.) See under Cream.

   Tartar emetic (Med. Chem.), a double tartrate of potassium and basic antimony. It is a poisonous white crystalline substance having a sweetish metallic taste, and used in medicine as a sudorific and emetic.

n. A kind of crust deposited in wine casks.