CFR › Title 27 › Part 21 › §21.115-T227 CFR §21.115-T2Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗Copy link(a)Specific gravity at 25 °C. 0.955 to 0.965.(b)Refractive index at 20 °C. 1.495 to 1.500.(c)Angular rotation. -57° to -62°.(d)Assay. Not less than 97.0 percent.