Some of the most fascinating things to come out of British and Irish bogs are the butter churns and butter crocks. I'll address that separately below, but I ran into a food experiment that I'd like to share.
Why did people deposit butter and tallow in bogs in the first place? Was this for preservation?
|Nordic Food Lab|
I found this very cool site "Nordic Food Lab" which carries out a scientific experiment to see how the qualities of butter might be improved or preserved in a bog. It appears they have found some practical success in demonstrating the purpose for making bog butter. I'm satisfied enough to say 'case closed'.
|3,000 year old Butter Container (National Museum of Ireland) via NBC News|
I came back to bog butter after seeing the butter barrel above, which is almost identical in size and shape to historic American butter churns. It's easy to imagine this 3,000 year old barrel having had a plunger before the lid was installed.
Really, the intriguing part is that it is a hollowed out oak log, not a staved cask. This presents a possibility for clarifying, in my own mind, how beer was fermented in Neolithic Europe, particularly the Early Bronze Age.
It seems like that the predecessor to staved oak barrels was simply hollowed out oak logs, possibly pitched with wax or butter fat, which allowed people to ferment large volumes of beer. For all of the drinking that Bell Beakers supposedly should do, no inorganic container is available in the record that would be large enough or strong enough to ferment.
There is direct evidence of oak lactones in Middle Minoan wine residues which Patrick McGovern (referred to in the previous post) suggests may be evidence of oak casking in the second millenium. (McGovern, 2003)
For the most part, beer and wine in the Mediterranean world was fermented in large clay pots (pithoi) then transported in amphorae and it is only in the Christian period when the northern style oak barrels overtake clay ones. Strabo referred to the Celtic staved barrels as "wooden pithoi", so we can have a fair amount of confidence of the complementary purposes.
I'm trying to guess at what volume a log barrel might hold, assuming something like this existed. I'm guessing the 3,000 year old barrel has the diameter of a Cornelius keg and slightly taller. So in my make-believe Neolithic beer keg, I'm guessing it'd hold about six gallons of beer, which is a little less than 3 American cases of beer.
The only way to test this theory would be an ultra-detailed chemical analysis of beer residue from beaker pottery.