?????????

I think what you see is what you got. I soaked a coin with similar corrosion for 5 months and got nadda. I used electrolysis on other coins and as you probably know from trying this yourself , that it removes most of the deposits , plus parts of the coin itself. That is a tough one , if you figgure something out , let us know. Good luck.

Don't think theres much to help that out, is it burned or salt water?
Either way I don't think much could help it, the Front still looks OK which is a plus, would be worse to have the front as messed as the back. no?

Like reaper says, the date side looks ok so I think I would leave it alone....if it was a 1963 dime then I would experiment but not on an old seated.
If that gunk is on top of the coin, a chemical or mild acid might remove it (lemon juice maybe) But if its corrosion that has lifted the metal of the coin then you are going to end up with pits and craters in your coin....