An automatic injector apparatus comprising an outer housing assembly, a hypodermic needle, first and second containers, a first liquid medicament ingredient in the first container and a second medicament ingredient in the second container, first and second pistons in the first and second containers respectively,...http://www.google.com.au/patents/US4755169?utm_source=gb-gplus-sharePatent US4755169 - Automatic medicament ingredient mixing and injecting apparatus
