Spreading at an incredible speed, and petrifying any organic victims that are caught within it as it enters their skin and body, it turns the recipients into a crude state similar to stone. However, if the petrification shell is broken open within half a day since infection, then the victims can still be saved.
When Caesar Clown decided to debut his newest gas weapon to brokers across the world, he lured Smiley with a piece of "bait" in the shape of a giant candy, which, when devoured, had Smiley regress back into his original gas form, with the bait's ingredients converting the H2S gas compound into an even deadlier form, decimating many of Caesar's centaur subordinates.
When Caesar was being cornered by Luffy to no end, he decided to let the Shinokuni gas flow into the lab and absorb the petrifying smoke into his body, which greatly enlarged him. He then claimed that two peaceful countries already wanted to purchase Shinokuni due to seeing the potential, and poured the gas onto his underlings as an exhibition for his criminal underworld spectators.
After Caesar was defeated, G-5 Marines tortured the captured scientist and forced him to reveal the weakness of the gas, thus giving them an opportunity to rescue the victims.