I'd like to hang some shelving on the wall in my kitchen that separates my home from my neighbor's. How can I figure out what material this wall is made of? The home was built in 1950. The party wall is completely solid if you knock on it with your knuckles and there's only one small metal object to be found with a magnetic stud finder; I'm assuming a screw or nail that was never cleaned up. It's smoothly finished and painted. Taking a hammer to it results in a lot of resistance and the tiniest indentation.
The interior walls are also sort of a mystery. I've hung two ceiling fixtures so I actually can describe them a little better: They're roughly a half inch thick, crumble when you try working on them and are hung directly to the joists in the ceiling. No lathes makes me think drywall but the crumbling makes me think otherwise.
This has always made it tough to do any work to the house. It's impossible to make a clean cut in the interior walls since they crumble and the party walls are very intimidating.