Cream of Tartar (Potassium Bitartrate) CAS: 868 14 4 Properties: White crystals or powder; soluble in boiling water; pleasant, slightly acid taste; insoluble in alcohol; d 1.984 (18C). Derivation: From wine less by extraction with water and crystallization. Grade: Technical, NF, FCC. Use: Baking powder, preparation of other tartrates, medicine, galvanic tinning of metals, food additive.