Caesium metal is highly reactive and very pyrophoric. Powdered thorium metal is pyrophoric&colon; it ignites spontaneously in air. Germane is a highly flammable, potentially pyrophoric, and a highly toxic gas. Cerium metal is used in ferrocerium lighters for its pyrophoric properties. Iron phosphide reacts with moisture and acids producing phosphine (PH), a toxic and pyrophoric gas. Other engines use pyrophoric fuel additives, such as silane, to avoid flameout. These reagents are highly reactive, and are sometimes pyrophoric. It is highly flammable and pyrophoric (self-igniting) upon contact with air. Solid pyrophoric payloads are based on iron platelets coated with a porous aluminium layer. Despite its highly pyrophoric nature, diethylzinc is an important chemical reagent. It is a colorless pyrophoric and toxic liquid. It is a colorless, pyrophoric gas with a repulsively sweet odor. Some are pyrophoric, most are used as air-stable slurries. The substance, often mistaken for napalm, is in fact TPA (thickened pyrophoric agent). Careful handling is required to avoid the production of pyrophoric metal powders.