Yeah they are. That's exactly what Firestorm does. J'onn did that fairly often during that time period. He always called it the "Martian art of transmutation."
This one is sort of confusing, because it takes place partially in Martian Manhunter's head and partially in the real world, where Malefic is controlling his body. At two points, Superman and Batman are able to get messages to J'onn, trapped in his own head, when Malefic thrusts him into their heads---or something along those lines. Superman says that what he's seeing is partially true (as in Malefic is really using his body to carry out these acts and the heroes are fighting him) and Batman tells him that he's destroying the world.
Here's the battle stuff the way J'onn is experiencing it:
The American Heritage Science Dictionary - Cite This Source - Share This transmutation (trāns'my-tā'shən) Pronunciation Key
The changing of one chemical element into another. Transmutations occur naturally through radioactive decay, or artificially by bombarding the nucleus of a substance with subatomic particles.
Adding atoms does not change the elements themselves. The writer is wrong here. If you have Fe and O going into the reaction, and you come out with Fe and O, that is not a transmutation. Basic chemistry.
Once again uses it to levitate things- this time some chemicals from Batman's utility belt, acting a bit like a living Martian vacuum cleaner. Also some uses of "fringe-breath" (like "martian art of transmutation", fringe breath is strictly pre-crisis power for Martian Manhunter, never used in post-crisis times, though superbreath and sonic scream were used a few times in post-crisis issues (those powers are well within established Martian powerset and given his power to control his body on molecular level, are easily replicable)). http://img301.imageshack.us/my.php?...jla01606uj7.jpg http://img301.imageshack.us/my.php?...jla01607ea5.jpg
Some more uses of Martian Brath power from pre-crisis times. In fact, given MM's shapeshifting prowess, those powers, directly related to the lung capasity and keeping the air in the lungs pressurized, are easily replicable by post-crisis version, as the lungs capacity of Martian Manhunter is theorecically unlimited- he can shift his lungs as much as he wishes.