Can anyone tell me what was in the little tube that came with old Polaroid roll films? It was supposed to be spread on the print after development. Is it some sort of fixer? I there something I can substitute?

I unearthed my Great Grandmother's Polaroid The 800 camera a year ago, fixed the shutter, and used it with some 4x5 film.
Occasionally I'll pick up some old 40-series film (usually Type 47). It's hit-or-miss; sometimes it is dried, but some rolls are still "good." The images aren't great, but are usable, and it is fun to use the camera as it was intended. Oddly, I've had better luck with film from the 60s as opposed to the 80s.

On the rolls that aren't totally dried, the little tube usually is, or is too sticky to spread on the print.
Basically, I want to keep the images that do come out from degrading (or, degrading more than was typical).