Today in 1890, US Patent 433015 A was issued, an invention of John Meyer, for his “Vent Bung and Bushing.” There’s no Abstract, although in the description it includes these claims:
My invention relates to bungs and vents, and is particularly intended for kegs and casks for beer, ale, and similar liquors, but is of course applicable to all vessels for storing liquids. Its object is to provide a vent-bung, which will at all times prevent the escape of gases from the vessel and preclude the admission of air, except when it is necessary to induce a flow of the liquid from the faucet of the vessel, which Vent will require no attention after the keg is filled and vent-bung inserted until it again be necessary to fill the vessel.
