Firkin

a small wooden cask used chiefly for butter, tallow, lard, soap, fish, etc. The first syllable of the term is derived from an old English word akin to the German vier, meaning four. A firkin is accordingly a little cask holding a fourth of a barrel. According to the laws of England the beer firkin contains nine gallons. A firkin of honey contains eight gallons; a firkin of butter, fifty-six pounds; a firkin of soap, sixty-four pounds; a firkin of fish, twenty-one pounds. See Cooper