A Further Study of the Air-Jet Method for Determining Gum in Gasolines

IN a previous paper covering a comparison of several methods for determining gum in gasolines, the conclusion was reached that the air-jet method gave the lowest and most reproducible results. Since gum deposition in the engine occurs in the presence of air, a more extended study of that method was undertaken. By evaporation of different volumes of gasoline and of various blends with a gum-free gasoline in each case, the concentration of gum and of gum-forming constituents was found to be one of the most important factors in determining the gum content. The temperature of the gasoline and the oxygen concentration in the atmosphere surrounding it during evaporation appeared to have little effect on the results. Further work on methods for determining the gum content is contemplated.