They have a filler in them,some used balsa wood, and that was filled with acetone. Plus an asbestos filter at the top. I would not follow the above advice on my property. You can try calling these folks to find out what the damages are- Not cheap, I imagine. http://www.cylinderrecycling.com/index.html
They are in Massachusetts, so it is probably not a viable option. My town has a hazardous waste collection day twice a year, but I am not sure if they would take something like that. This has been a looming problem for years in the gas business.