Today in 1899, US Patent 635474 A was issued, an invention of August Grap, for his “Keg Refrigerator.” There’s no Abstract, although in the description it includes these claims:

This invention relates to an apparatus for preserving the volatile hop essences or aromas coming from the copper or boiler in which the wort is boiled with the hops in order to improve the quality of the beer and like brews.

The method and apparatus comprised in the present invention consists in arranging a specially constructed condenser in communication with the top of a copper whereby the vapor arising from the heated contents of the latter will pass to and be condensed in the former.

The condensed vapor or steam is delivered to a supplementary cooling .coil and thence to a mixing chamber where it is brought into contact with the non-condensable or practically non-condensable odoriferous gases for fumes which pass from the upper end of the condenser and are collected and delivered to the said chamber in a convenient way.

The liquid resulting from the condensation of the steam or vapor given out from the copper absorbs the aroma of the odoriferous gases or fumes in the mixing chamber and as a result is richer in flavor and aroma than the original liquid contents of the said copper. The liquid is conveyed. from the mixing chamber to an open vessel or chamber from which it is delivered to a ferment ing vat.