How do you know if old paint on the wall is oil based or latex?

I would like to repaint the interior of my house. I'm not sure if the paint is oil based or latex, and it has no chipping or wear. Can I prime with a latex, then paint latex, even if it's oil based?How do you know if old paint on the wall is oil based or latex?
primer should stick to either type of paint..your on the right track if you prime with a latex primer use latex paint too...How do you know if old paint on the wall is oil based or latex?
Couldn't you just peel a chip off and take it to your local decorating center or paint/hardware store? My first concern, if it's an older home, would be if lead were present in the paint.
best solution is to use a primer or Kilz to prime the walls
YOU DON'T NEED TO KILTZ THE WALLS BUT YOU CAN LATEX PRIME IT THEN LATEX PAINT IT. I'M NOT SURE IF A PAINT DEALER CAN TELL YOU BUT IT MAY BE WORTH A TRY TO ASK. IT SEEMS TO ME THAT OIL BASE PAINT IS MAINLY USED FOR EXTERIORS BUT I COULD BE WRONG. A PAINT DEALER COULD HELP THERE, TOO.





YOU COULD PAINT A VERY SMALL SECTION AND SEE HOW IT LOOKS ALSO IF YOU CAN'T FIND OUT ANYTHING ELSE. GOOD LUCK...