Firkin is a size of cask. I can't remember the other sizes and the Oxford's Companion is just out of arms reach. EDIT kilderkin and hogshead
Correct to all above. The standard size cask in the US and beyond is a firkin- 9 Imperial gallons aka 10.8 US gallons. You may sometimes encounter a Pin, which is 1/2 of a firkin...5.4 US gallons, but rarely, if ever, a kilderkin or hogshead...just too damn big!
Saw several kilderkins outside a pub in London last summer, in a stack of casks to be picked up. They were greatly outnumbered by the firkins in the stack. Rare but not extinct.
Schlafly from St. Louis is bringing a kilderkin to a beer festival at one of my favorite bars in September.
