Cat 🐈🥗 (D.Burch) 
Butane floats on water because it's a lighter fluid.
SpaceLifeFormAnd Propane sinks in air.
Leonardo Ferreira Fontenelle@SpaceLifeForm so does butane, right?
Butane immediately evaporates if the temp is above freezing and mixes into the air.
Propane does not immediately evaporate, and hugs the ground.