A yellow solid, C8H7N, m.p. 52°C. Its molecules consist of a benzene ring fused to a nitrogen-containing five-membered ring. It occurs in some plants and in coal tar, and is produced in faeces by bacterial action. It is used in making perfumes. Indole has the nitrogen atom positioned next to the fused benzene ring. An isomer with the nitrogen two atoms away from the fused ring is called isoindole.