Corrosion is the process of losing a refined metal (recovered from the Ores), by chemical reactions with chemical reagents to form its Oxide, Sulphide or its metal salt. Thus oxidation is one form of corrosion of metals to form their oxides. Corrosion of Metals also happen by other chemicals like Sulphur, Sulphur Dioxide, Sulphur Trioxide or Acids and other Chemical Agents. Metals like Silver and Copper, react with Sulphur from Atmosphere or Hydrogen Sulphide to form their Sulphides. Acids like Sulphuric Acid or Hydrochloric Acid react with metals like Iron and Aluminium to form salts like Iron Sulphate or Aluminium Chloride.