” Some arsenic trioxide finds its way in to the air. Condensation from the vapors on the floor at temperatures higher than 250° C forms the glassy modification, which slowly and gradually variations towards the crystalline, monoclinic type. Inside the processing of As2O3 the oxide is Generally minimized withcarbon: 2As2O3+3C?→As4+3CO2 http://https//chemscenter.com