What do I do with 40 year old batteries?

So I bought a vintage camera. A Kodak Brownie Hawkeye. It came with a side flash bulb thing that takes 2 AA batteries. Its called a kodalite midget flasholder. Well they were left in it and have leaked everywhere ruining it. Are they super dangerous or anything since they are sooo old. They say Electrex flashlight battery on them..they look ancient! What do I do with them. I've never seen batteries this old.