The Mist can apply his inviso-solution to living and non-living things to make them invisible. However, Starman's cosmic rod produces a special light that makes things treated with the inviso-solution visible, within the path of that light beam. If Starman concentrates the beam on the person or object treated with the solution, the solution will wear off entirely. Originally the Mist treated his cloak the inviso-solution, but not enough to make it completely invisible. Hence, the Mist appeared to be no more than a head, and sometimes hands as well, floating atop small, shifting clouds.
Chemistry * Physics
The Secret Society of Super-Villains
Long ago the scientist now known as the Mist created an "inviso-solution" that could turn people and objects invisible. He tried to sell it to the United States government during World War I only to be met with rejection and scornful disbelief. The Mist vowed revenge and, after World War II began in Europe, sent his invisible agents to steal all of America's military secrets. He also tried to use invisible planes to bomb factories geared for defense. However, the Mist's schemes were thwarted by the man who became his principal enemy, Starman.
Later, the Mist used a variation on his inviso-solution to hypnotize innocent people into robbing for him. Starman foiled the Mist again. Decades later, the Mist tried this plan once more but was defeated by Starman and the Black Canary.
Over the years the Mist's repeated use of the inviso-solution had a cumulative effect, enabling him to take on a truly mist-like form. He became a member of the Ultra-Humanite's Secret Society of Super-Villains. However, the Mist and other Society members became entrapped in a limbo-like dimension, where they remain to this day.