CINNAMIC, sin'a-mik, ACID, an acid which exists in the free state in the balsams of Tolu and Peru, in liquid storax and in gum benzoin. It occurs in two forms, slender needle-like crystals, and large transparent prisms, melting at 270° F. When oil of cinna mon is exposed to the air it absorbs oxygen and deposits crystals of cinnamic acid, which are colorless and readily soluble in alcohol ether i and boiling water, but sparingly soluble in cold water. It is not of any importance in the arts and is chiefly interesting as being the acid corresponding to oil of cinnamon. This oil is the aldehyde of cinnamic acid and is repre sented by the formula Glis03. Though isomeric with oil of cassia it has a slightly different flavor, and is much more expensive. Both of these oils are employed in medicine as aromatic stimulants, but chiefly as pleasant adjuncts to disguise the taste of nauseous drugs. From a
chemical point of view, the cinnamic acid and oil of cinnamon are related to benzoic acid and oil of bitter almonds. Oxidizing agents con vert it first into benzaldehydc and then into benzoic acid. It unites with hydrogen to form hydrocinnamic acid.
Cinnamic acid is one of the active prin ciples in many of the balsams and enjoys an excellent reputation in the treatment of tuber culosis and chronic ulcerative processes. It is a marked stimulant to the skin and mucous membranes and has been very widely used in the form of an emulsion for the treatment of tuberculosis of the joints. It is prepared in quantity by keeping one part of benzaldehyde, one part of acetyl chloride and three parts of sodium acetate at a temperature of 320° F. for 24 hours.