Gum Resins

plant resins containing gum (11–55 percent) and, often, volatile oils.

Gum resins are distinguished from other resins by their incomplete solubility in ordinary organic solvents. They are completely soluble in a 60 percent water solution of chloral hydrate. Large amounts of gum resins are found in plants of the Umbelliferae family. They are used in medicine to make plasters.