RESIN-RUBBER FROM CANADIAN GROWN PLANTS: IV. ANALYTICAL STUDY OF MILKWEED POD GUM

Abstract

Fresh pod gum has an acetone-soluble content (resin) of 83.4%, and a benzene-soluble content of 7.3%. Steam distillation of the resin furnishes a small amount (0.1%) of an essential oil. Acidification of the saponifiable portion (55%) of the resin yields an oil consisting of a mixture of fatty acids. Palmitic, stearic, oleic, linoleic, and linolenic acids were identified. Resin acids are absent. The unsaponifiable portion (45%) contains a large amount of α-amyrin, and extremely small amounts of sterol (probably heterogeneous) and resene. Polyisoprene, an oil containing free acids, and an unsaponifiable residue make up the benzene extract. Water-solubles include calcium tartrate, soaps, and a material yielding a mixture of sugars on hydrolysis. The residue comprises lignin, cellulose, protein, and inorganic materials. From these data the dry gum contains approximately 50% of fatty acid esters, 26% of α-amyrin, 6% of polyisoprene, 4% of ash, 3% of lignin, 2% of cellulose, and small amounts of protein, sterol, resene, essential oil, and calcium tartrate. Unidentified substances comprise 7.7%.