Today in 1894, US Patent 531314 A was issued, an invention of A.M. Hofmann, for his “Process of and Apparatus for Preparing Beer.” There’s no Abstract, although in the description it includes this summary:
It may be stated at the outset that I have primarily designed my improvement for the particular application to beer in barrels or kegs orin bottles, and I therefore, and for the sake of convenience, hereinafter confine the description of my invention in its application to racking, carbonating and bunging beer, though it is also applicable to, and I desire to be understood as intending it for, any and all liquids or beverages requiring similar treatment to prepare them in receptacles for the market.
A known manner of carbonating a beverage to prepare it for the market is to introduce into the holder containing it a liquid (preferably of the same kind) in small quantity proportionately to the quantity contained in the holder, but so highly charged with the gas, for which -,it affords a vehicle and a mixing or incorporating medium, as to supply the contents of the receptacle,and thoroughly impregnate them, with a charge of gas adequate for all requirements in the beverage.
I find that where the carbonating procedure referred to is employed on beer, the diffusion of the gas through the beer in the receptacle, however thoroughly it may be produced, is not lasting where the receptacle is not completely, or at least approximately, filled with the beer to be charged, which it rarely is; since the space left on filled affords, as it were, a pocket, in which the gas tends to accumulate, and whence it quickly escapes on opening or venting the receptacle, leaving the beer, when poured or drawn for consumption, insufficiently carbonated. Incomplete filling of the receptacles is, perhaps, as likely of occurrence where the receptacles are glass bottles as where they are barrels or kegs, notwithstanding that the transparent nature of the former renders the matter of completely filling them readily accomplishable.
My process consists in withdrawing from a .receptacle after filling it with beer (taken by preference directly from the cask) a suitably small proportion of its contents, and replacing the quantity thus withdrawn with an equal, or approximately equal, quantity of liquid highly charged with gas, thereby, practically, withdrawing the desired quantity from the receptacle, then charging it excessively with gas, and returning to the receptacle the same liquid, charged, that was withdrawn from it. Thus, after a receptacle has been completely filled, or substantially so, with the beer to be carbonated, (and complete filling of a barrel or keg is a matter as simple as filling a bottle) by withdrawing ascertain quantity to make room or the charge, and replacing it with an equal or substantially equal quantity of the supercharged carbonating liquid, the desirably full condition of the receptacles is attained.