FANTASTIC FOUR (1961) #22

As Ben Grimm and Johnny Storm look on, Reed Richards tests the nature and extent of Sue Storm;s invisibility power with a nuclear measuring device. When the test is finished Johnny decides to pull a prank and heat up the floor where Ben is standing. Annoyed, Ben grabs a chemical foam fire extinguisher/ But instead of hitting Johnny, the foam heads for Sue who suddenly summons up a shield of invisible energy that keeps the noxious chemical from touching her. Reed, Johnny, and Ben are astonished at Sue’s new ability, and Reed assets that the radiation from his measuring device must have increased Sue’s power. But the shield is still too thin, Reed says.…