This story was from a comic book I read somewhere around the mid-'60s. It was a normal-sized thin comic book, not one of the thicker "special issue" types. I believe it had several unconnected stories in it. The story I remember is about a scientist and his assistant and a time machine.
The opening panel shows them testing the machine by sending a chair to another time. As I remember, it was a brown wooden chair bathed in yellow light from the time machine. As they watch the chair fades away and disappears. They're elated, but have no idea whether the chair went into the past or future.
Later the assistant kills the inventor. I think it was because he was jealous that the scientist would take all the credit for the invention and would be the first to travel in time. Or it might have been simple theft, because the scientist kept a considerable quantity of gold in the lab. Anyway, the assistant kills him, takes the gold and has the machine send him to another time. He figures that wherever he ends up in history, past or future, the gold will make him rich.
But he arrives in a hellish landscape of barren rocks and volcanic eruptions. The gold is useless; there doesn't seem to be any civilization and maybe even no plant or animal life. As the story ends he laments that he'll never know whether he went to the distant past before life began on Earth, or into the distant future when Earth has become uninhabitable.