40s 50s vintage bubble lights biscuit shape, lot replacement light bulbs untested C6?

Lot of five vintage bubble light bulbs, plastic with glass tubes, not sure of the maker of these though I believe they're all of the same vintage, probably from the same set.

These have small socket bases (C6, I think) not like the newer reproduction bubble lights. I don't have a string that fits these, so I haven't tested them, and don't know if they light or bubble (one is empty of fluid, so that one I know doesn't bubble). Plastic looks good, no chips or cracks to the glass, metal fittings are a little tarnished.