Weird wire insulated with Lead

Picked up a small load the other day that included some 1" conduit apparently from an old underground service.
Looked like two runs of Romex inside the pipe but on closer inspection it was ....gray and soft.....LEAD insulation !
Added up to 101' of wire, about 30#. I stripped it by just slicing it down the center with a sharp utility knife.
Ended up with 8# of #1 insulated and 22# of lead. YeeHaa......sure beats throwing the insulation into the trash!!!
Dealt with a lot of wire over the years but this was my first "leaded" wire. Wonder how old this stuff is?