Today in 1909, US Patent 917019 A was issued, an invention of Gustav Detlefsen, for his “Apparatus for Mixing Liquids with Gases.” There’s no Abstract, but here’s how it’s described. “This invention relates to an improved apparatus for mixing liquids with gases, the device being more particularly designed to charging beer with carbonic acid gas while the beer flows from the chip cask to the racking apparatus. The construction is such that the liquid is thoroughly agitated while being charged with the gas, so that an intimate mixture is obtained.”