Hypodermic device

Claim 1

IN A HYPODERMIC INJECTOR ACTUATED BY GASES GENERATED BY AN EXPLOSIVE FOR DISPENING LIQUID MEDICAMENT FROM AN AMPOULE, SAID INJECTOR INCLUDING BARREL MEANS, AMPOULE HOLDING MEANS ATTACHED TO ONE END OF SAID BARREL MEANS, PISTON MEANS SLIDEABLY MOUNTED WITHIN SAID BARREL MEANS AND HAVING A PLUNGER ADAPTED FOR ENGAGING AN AMPOULE, EXPLOSIVE RECEIVING MEANS AT THE OTHER END OF SAID BARREL MEANS, AND MEANS ADAPTED FOR FIRING AN EXPLOSIVE POSITIONED IN SAID EXPLOSIVE RECEIVING MEANS, THE IMPROVEMENT, COMPRISING GAS TRANSFER MEANS BETWEEN SAID EXPLOSIVE RECEIVING MEANS AND SAID PISTON MEANS INCLUDING FIRST AND SECOND CHAMBERS AND A METERING PASSAGEWAY CONNECTING SAID FIRST AND SECOND CHAMBERS, SAID GAS TRANSFER MEANS OPERABLE TO CONVERT THE RAPIDLY EXPANDING HIGH PRESSURE GAS GENERATED BY THE FIRING OF AN EXPLOSIVE INTO SAID FIRST CHAMBER IN COMMUNICATION WITH SAID EXPLOSIVE RECEIVING MEANS TO A LOWER PRESSURE AND SLOWER EXPANSION OF THE GAS BLED THROUGH SAID METERING PASSAGEWAY INTO THE SECOND CHAMBER, AND MEANS IN SAID SECOND CHAMBER FOR RETARDING THE DECAY OF PRESSURE OF THE GAS ACTING UPON THE PISTON.