” Some arsenic trioxide finds its way into the air. Condensation of your vapors with a floor at temperatures over 250° C forms the glassy modification, which slowly changes to your crystalline, monoclinic kind. Within the processing of As2O3 the oxide is Usually decreased withcarbon: 2As2O3+3C?→As4+3CO2 The response is endothermic http://https//chemscenter.com