In Fischer Ringe's method, air free from moisture and CO2 is passed over a heated mixture (800∘C) of 90%CaC2+10%CaCl2 in an iron tube, when following reactions take place CaC2+N2
800∘C
→
CaCN2+C 2C+O→2CO C+O2→CO2 2CaC2+3CO2→2CaCO3+5C CuO+CO→Cu+CO2 CO2 gas is now absorbed by KOH solution. Thus a mixture of inert gases is obtained