I am having an arguement with a friend.  He hooked a battery charger
to his car, put the POS clamp on the battery, and the NEG one to his
gas line near his carburetor.  I just about had a stroke when he did
that, and I unplugged the charger immediately.  He told me I was being
paranoid and because the gas is inside the pipe it cant ignite, and
said he does that all the time because its and old car and the body
metal is rusty and the engine metal is painted.  

He insists this is not dangerous.  I disagree.  Then he clamped it to
the gas line there were sparks.  What if they burned thru the line if
there was a weak spot in the metal?  I told him I am sticking by my
words, "it's dangerous".  

I know you should not connect both clamps to the battery terminals, so
I always connect the NEG to the alternator bracket, and have connected
it to the bumper, bolts on the fenders, and any other metal that's not
painted or rusty, but NOT the gas line.  

So who is right?  I believe I am but I'm asking.  I'd hate to think if
he connected a jumper cable to the gas line, which has enough zap to
weld right thru a gas line.