Mercury is used in its pure form in thermometers and barometers. Many batteries contain mercury. It is used in floodlights, streetlights, and other outdoor or powerful lights. It is also used as a catalyst in the chemical manufacturing industry. It is used to conduct electricity (i.e. thermostats). Mercury is used in dental amalgams. It is also used in the mining industry to extract gold and silver ores. Mercuric chloride is used in the manufacture of disinfectants, other chemicals, and as a catalyst. Mercuric chloride is used in photography and embalming. Bacteria in the water and the soil primarily produce methyl mercury.