The syringe has an outer casing open at one end and a cylinder reciprocable within the casing in which latter works a plunger; the cylinder is spaced from the inner periphery of the casing to form an outer chamber and the space within the cylinder forms an inner chamber, each chamber to contain the ingredients...http://www.google.co.uk/patents/US4185628?utm_source=gb-gplus-sharePatent US4185628 - Compartmental syringe
