1.1 ,This test method covers the determination of unsulfonated residue in plant spray oils of petroleum origin and applies only to the petroleum oil content. It provides a measure of the degree of refinement of plant spray oils by determining the extent to which the oil is attacked by 98.61 ,% sulfuric acid under closely standardized conditions. Since the relationship between unsulfonated residue and the actual composition of the oil is not known, this test method should be applied only for measuring the degree of refinement and not for the determination of aromatics or olefins, or both.