The mixture is heated with double of its amount of anhydrous sodium carbonate and heated in a charcoal cavity by luminous (reducing) flame.
The metal carbonate is reduced either to coloured metal oxide or metal.
(i) Red flakes Copper salt
(ii) Black or brown residue Fe or Mn salt
(iii) White metallic bead that marks paper Lead salt
(iv) Yellow white hot, and white when cold Zn salt
In case residue is white, it is heated with 1 or 2 drops of cobalt nitrate solution when metal cobaltates are formed some of which have characteristic colour.
Blue-Al, Green-Zn, Pink-Mg
