When did Superman first get heat vision?

[DrNewGod]

Superman's powers have come a long way since S&S four panel description in 1938. Now by 1942, he had X-Ray Vision (at least, according to Fleisher's cartoons). When though, did he start melting/incinerating stuff just by staring at it too hard?

[seismic-2]

As I recall, all throughout the 1950s he didn't have a separate "heat vision". In the stores of that era, his X-ray vision generated sufficient heat to melt things (or just warm them up, as necessary). I didn't read many super-hero comics after that, so I don't know when the two super-powers were declared to be distinct rather than just two aspects of the same thing. I always thought it was pretty stupid that somehow he was supposed to emit X-rays from his eyeballs. After all, normal vision doesn't work that way!

[jetengine]

When they realised X-rays are actually fairly dangerous to the himan body they shifted them to a heat vision and a seperate X-ray (but not actually using X-rays) vision.

[Jim Kelly]

It seems to me, in the earliest stories, Clark is just looking intently through a solid object and can see what's behind it. I don't think this was called x-ray vision at that point. Soon it was called x-ray vision, but it was passive and it was probably just an easy way to describe what Superman is doing. At this point, they're on substantial ground as far as the science. There's enough x-rays emitted by the sun that everyone and everything on Earth has x-rays passing through them all the time. You can't do a proper x-ray with that--so you need to emit greater intensity x-rays through something; however, we can just assume that Superman's eyes have a greater sensitivity to natural x-rays, so he can see through things all the time. It's pretty well the same as seeing things in the dark with infrared vision--the difference being that x-rays are shorter in wavelength than visible light, while infrared is longer.

Where the writers went wrong was when they presented Superman as definitely emitting x-rays from his eyes, since that wouldn't work how they wanted--in order to see through anything. But that's when his x-ray vision could clearly be used as heat vision--because, if he can emit electro-magnetic radiation from his eyes, then he can heat things up with that radiation. He does that in SUPERMAN 59 (July-August 1949), but this is always described as x-ray vision. It isn't called heat vision until ACTION COMICS 275 (April 1961). Source: CBR--"When Did Superman First Use Heat Vision in the Comics?"