Mythos be busting out all over the place, with the introduction of another major element of Superman stories being introduced in Adventure Comics #283 (February 1961): The Phantom Zone! Superboy discovers some Kryptonian machines sent into space (by Jor-El of course) and learns about how the Phantom Zone was where Krypton placed its dangerous criminals for rehabilitation. In this story, it is not stated that Jor-El created the Phantom Zone.
Superboy then learns about another character which will later have a big impact on Superman mythos: General Zod. Zod is only shown in flashback-form in this tale, where he is sentenced to the Zone for building a clone army to overthrow the government.
But woops, while Superboy is listening to the helmet explain the Phantom Zone to him, a lizard happens to turn it on, projecting into the dreaded Zone, where he can see/hear everything going on, but has no presence in the physical world, people cannot see/hear him and he cannot physically interact with the world.
Hey, don’t worry too much though, it seems like Superboy has figured out a way to communicate after all. By concentrating, he can make typewriters and electric machines react. He quickly sends a note to Pa Kent, who rushes to free his son.
It’s a cool story element that will be explored pretty heavily later on, so I can see why they kept this one so short. However, if all it takes to escape from the Phantom Zone is to concentrate on interacting with electronic machines they might have made it too easy.