What is a nitrogenous base homologous with pyridine, obtained from coal tar as an oily liquid, C11H17N; also, any one of the group od metameric compounds of which rubidine is the type called?

rubidine — A nitrogenous base homologous with pyridine, obtained from coal tar as an oily liquid, C11H17N; also, any one of the group od metameric compounds of which rubidine is the type. (Webster's 1913.)