What Kind of Wagon is THAT?

I've been to a LOT of museums in my lifetime and considering I grew up on a farm, was a 4Her and a daughter of a man who LOVES history I've been educated about antique farm equipment. But on our way home from Oklahoma on the Eight. Hour. Drive. I needed a break so we took a short detour to see a sod house museum. It was closed but there was plenty of equipment outside to take a look at. 

When I saw this wagon I was stumped. It looked like a beer barrel. Could they have hauled beer on a wagon? That didn't make sense. Though it would have been darn cool to have a huge keg of beer delivered! 

Especially when this was what the front looked like. I kept thinking if it were beer then the tap would have been at the back and that sure didn't look like a tap to me. But with the curved shape to the wagon it had to have hauled some sort of liquid...but why??? 

I was stumped and sent the photos to my dad who came through with the answer, of course. And I must say once I figured out what this wagon was for it was a "DUH" moment. Obviously, THAT was what it was used for!!! 

So, do you have any guesses?? What was this wagon originally used for? 

Answer tomorrow!