Not sure on any specifics on what these had in them, but it was likely Tincture of Iodine or something along those lines. For having been dug that one is in great condition, with stunning color!
This is a KS-2. From my site:
These came in 4 sizes: 3 1/4, 4 1/2, 5 & 7 3/4” The sizes larger than 3 1/4 are very rare. They come in Clear, amber, cornflower, cobalt and Moss. There are no 3 1/4” in Moss known.