Today in 1895, US Patent 534541 A was issued, an invention of Joseph Earl Wright and Edwin A. Grover, for their “Faucet and Attachments Therefor.” There’s no Abstract, although in the description it includes this summary:

Our invention is an improved faucet, and attachment, for. use in drawing beer, or any other liquid with which it is desirable to pre vent the contact of air within the keg. The faucet is provided with a sliding attachment, comprising an inflatable airbag, and a fixed and sliding tube for pushing the bag out of the faucet proper into the keg and subsequently permitting injection of air, and also with valves for regulating the discharge of the contents of the keg. The construction of the device is such that it is cheap and durable, and is adapted to be used in place of the ordinary beer-faucet.