If there is no obvious appearance o

If there is no obvious appearance of the object to be examined, it may be considered to be identified by heating (many substances will chemical reaction when heated, and different phenomena will occur, such as ammonium, nitrate, acid carbonate, etc.) . This method can be used to deal with the iron evidence with shallow corrosion. The main component of iron rust is ferrous oxide, its molecular structure is relatively loose, and the iron money body adsorption is far less solid than copper, so using the principle of thermal expansion and cold contraction can make part of iron rust off.