Assumed when I bought this that it was some sort of decanter, it was caked in grime and completely gummed up, a thick liquid in the top section was probably shampoo. it appears to be a juice decanter, the lower chamber for water and the smaller top for the juice, lemon or lime would work or maybe a concentrate instead.
It reminded me of Kaj Franck's Kremlin Kellots and it is this Phillips auction description that points towards the intended use:
https://www.phillips.com/detail/kaj-franck/UK050415/218The shape looks very deco to my eye, roughly 24cm tall. The uranium glass has a slight blue tint, not a clue as to maker, expect it would be a tough item to identify.
John