Mace is the genericized trademark of Chemical Mace, the brand name of an early type of aerosol self-defense spray invented by Allan Lee Litman in 1965. The first commercial product of its type, Litman's design packaged phenacyl chloride (CN) tear gas dissolved in hydrocarbon solvents into a small aerosol spray can, usable in almost any environment and strong enough (when sprayed in the face) to act as a credible deterrent and incapacitant. Its popularity led to the brand name being shortened to simply "Mace" for all defense sprays (regardless of the composition). It is unrelated to the spice, mace.
Chemical Mace was originally invented in 1965 by Allan Lee Litman, founder and co-owner of Pittsburgh-based General Ordnance Equipment Corporation (GOEC), after his wife, Doris, was threatened on the street. In 1987, Chemical Mace was sold to Smith & Wesson and manufactured by their Lake Erie Chemical division. Smith & Wesson subsequently transferred ownership to Jon E. Goodrich along with the rest of the chemical division in what is now Mace Security International. Though the design has been expanded on, the original Chemical Mace formula using only CN has since been discontinued. Due to the potentially toxic nature of CN and the generally superior incapacitating qualities of oleoresin capsicum (OC) pepper spray in most situations, the early CN has been mostly supplanted by OC formulas in police use, although Mace Security International still retains a popular "Triple Action" formula combining CN, OC and an ultraviolet marker dye.