Shazam#12(1974)

A time traveler from the future, Jarl 499-642-831, comes to visit Billy to find out why this is the one day where they have no record of Captain Marvel doing anything heroic. Billy takes him to see Professor Kilowatt's new invention, which is a ray that turns anything to gold. After a brief diversion where Captain Marvel saves Kilowatt from being trapped on a runaway weather balloon, Kilowatt demonstrates his ray. Unfortunately it's much more powerful than he expected and anything turned to gold turns anything else it touches into gold also. Cap, who is immune to the Midas effect, holds up all the golden items so they're not touching the ground. However, Kilowatt points out that this is a temporary solution, because eventually, the Midas effect will spread through the very air. Cap then crushes the Midas gold into a lump the size of a pill, and suggests he drop it into the sun. But Kilowatt vetoes that idea as well, because it would turn the sun into gold and everyone on Earth would die. Kilowatt bemoans the fact that soon, he'll turn into gold as well, except for his gold fillings. This gives Cap the idea to use the natural gold in Kilowatt's fillings to wrap around the Midas gold, since the Midas effect has no effect on natural gold. Cap then flies off to hide the Midas Pill where no one will ever find it, and everyone involved vowed to keep it secret so it didn't fall into the wrong hands. This is why there was no record of Captain Marvel doing anything heroic that day. Jarl accepts this and returns to the future, also vowing to keep the secret.