I came across a reference to:

"a chemical solution for soaking wood. This solution stabilizes the surface so it will not shrink, crack, or split. It had been invented by government workers to preserve wooden gun handles."

The reference dates back to the 1950's.
Anyone know what this chemical solution could be?

It sounds like pentacryl. Most commonly used by woodturners. I'm not sure of the origin of it, so that may not be what they are referring to.