a. - Pertaining to, derived from, or designating, an organic
acid which is produced in the distillation of wood, in the fermentation
of various organic substances, as glycerin, calcium lactate, etc., and
is obtained as a colorless liquid having a sharp, pungent odor.
Propionic acid is so called because it is the first or lowest member of
the fatty acid series whose salts have a fatty feel.