Today in 1878, US Patent 204687 A was issued, an invention of Henry Shlaudeman, for his “Improvement in Safety-Valves for Fermented-Liquor Casks.” There’s no Abstract, though it’s described this way in the application:

The object of my invention is to produce a safety-valve to be placed upon storage-casks, hogsheads, &c., in which malt and other fermenting or fermented liquors are placed in stock viz., before drawing into vessels for consumption or sale-and is constructed so that the weighted valve will be raised automatically if more than a certain quantity of carbonic-acid gas is generated, and allow said gas to escape without exposing the liquors to the open air, and by thus excluding the air stopping fermentation at a fixed degree, and preventing the bursting of the cask or hogshead, the device inclosing a weighted valve that shall have a fixed and definite capacity of retaining the gases.