...at least I think so, in an antique / curio / consignment shop. I will need help in identifying what it is. I will post pictures and confirm the dimension too.
I saw it Friday and made the shop an offer (tin or not - it is 100% unique). Its owner was not immediately available for negotiation. Late yesterday, through the shop, he agreed to my offer. I go to pick it up when they open this morning.
In my Mind's Eye, the pot is a "truncated heart" shape, ~18" tall; slender and flat, ~8" in dia., at the bottom; ~18" in dia. at the upper 1/3; and tapered in the top 1/3 to close against a "proud lip" ~3" tall and ~4" in out-to-out dia. The walls are ~3/16" thick. These dimensions will be verified.
The interior is rough, but the outside is hand smoothed from decades / century of use, dull gray, malleable metal (very lightly dented in a place or two), and ~30-pounds in total weight. The lid, at ~3 pounds, is hemispherical, like a "mushroom", ~5" in diameter, complements and completes the overall shape of the pot, is hand smooth, very close tolerance that creates a vacuum to remove, and slip fits over the proud lip. There are no handles. Carrying the circular pot is "a chore".
Under the lid, is a close fitting, ~4" dia., "closure plate" of the same metal which is ~3/16" thick with a ~3" long by ~3/4" cylindrical "dongle" that hangs down in the middle (no clue for what this was intended - guesses?). The closure plate rests on a cast rim inside the proud lip and does not interfere with the lid.
A hollow 18" diameter sphere of 3/16" thick Lead weighs 38.7 pounds (too much). The same hollow sphere of Tin weighs 24.8 pounds (just right), which is why I think it is made of Tin and the pot made for keeping consumables cool (milk, cheese, butter, etc.), as in a mountain stream.
I will scrape metal from the rough interior, at the proud lip, to send for assay to determine the base metal. To whom should I turn for this assay? There is also a Chinese / Japanese / Asian / Indian cartouche on the base, like a Mfg's mark, which I will post for someone to identify / read / translate.
Forgive me for "teasing" you with this (until I get pictures). As I put my hands on it again, when it is mine, I will verify dimensions, weight, and with a little help, what it is. Keeping its form and function, i.e. not melting it, is a possibility.