Carbonic acid readily decomposes under normal conditions into gaseous carbon dioxide and water. It thermally decomposes into disulfide and elemental sulfur. As mentioned below, formic acid readily decomposes with concentrated sulfuric acid to form carbon monoxide. Ferric chloride decomposes to ferrous chloride at high temperatures. The potassium cyanide slowly decomposes, releasing hydrogen cyanide. Under acidic conditions, geosmin decomposes into odorless substances. Like most ammonium salts, ammonium perchlorate decomposes before melting. The compound readily decomposes into oxygen and fluorine. This amalgam eventually decomposes to release ammonia and hydrogen. At high temperatures in air, it decomposes or burns to produce poisonous phosgene. Ammonium carbonate slowly decomposes at standard temperature and pressure through two pathways. When peat dries it decomposes, and may additionally burn. Phenyl(trichloromethyl)mercury decomposes thermally to release CCl. It decomposes and turns into carbon dioxide (), which is released into the atmosphere. It decomposes in neutral or acidic aqueous solutions, but is stable at pH 14.