Beautiful cobwebby fine cotton crochet lace, a square about 88" x 88". This was probably made (and used, judging from the spots!) as a tablecloth.
It's in fixer - upper condition right now, but with a little work could be a lovely bed cover or throw, too.
This has a couple of BIG holes which need repair, and the aforementioned spots which we have not attempted to remove. You'll want to mend it before soaking, unless you're planning to use it as a cutter for projects.