Similar provisions were contained in former chapter 4, comprising former sections 301 to 303 of this title, which was set out here but which was not a part of this title. Former sections 301 to 303 were derived from act Aug. 8, 1950, ch. 646, §§1–3, 64 Stat. 419, and were repealed by section 56(j) of act Oct. 31, 1951. Subsec. (l) of section 56 provided that the repeal should not affect any rights or liabilities existing under the repealed sections on the effective date of the repeal (Oct. 31, 1951).