About Theoretical Calculation of the Protective Gas under the Production of Float Glass Xu DamoThe paper is a presentation of the thermodynamic theoretical calculation for the seven protective gas compositions (A.B.C.D.E.F.G) in the floatation process of glass in five different temperatures ranging from 600 to 1000℃.The calculation shows; all six protective gas compositions other than protective gas A can be used for the floatation production of glass.