Our house was built in 1950 and a family room addition was built sometime in the 60's. The walls are covered in the nasty wood paneling with some kind of insulation that was sprayed behind the walls. You push or hit the wall and a gray color cotton like stuff comes out. I want to know if anyone has any idea of what type of insulation was used at the time? I hope it does not have asbestos...

Sound like blown in rock wool insulation. It was a cellulose based product and did not contain asbestos.

Chuck

I agree with creahands but I also tend to not assume anything when it comes to safety. You can get it tested but tell us if you are planning on remodeling or what?

Rock wool and cellulose are two very different products. Rock wool was made from the same glass fibers as fiberglas but was much heavier and not as spun out into strands.
I removed a huge attic full of both once, rock wool on the walls and cellulose in the ceiling. Yours is probably cellulose, a natural plant product.