CFR /  Title 27  /  Part 30  /  Sec. 30.72 Recording obscuration by proprietors using the optional

Any proprietor using the optional method for determination of proof for spirits containing solids of 400 milligrams or less per 100 milligrams as provided in Sec. 30.71 shall record the obscuration so determined on the record of gauge required by 27 CFR part 19. (Sec. 201, Pub. L. 85-859, 72 Stat. 1358, as amended, 1362, as amended (26 U.S.C. 5211))