Section, act Feb. 25, 1920, ch. 85, § 4, 41 Stat. 439, provided for the leasing of an additional tract of land or coal deposit, not to exceed 2560 acres, upon a showing by a lessee that all workable deposits of coal would be exhausted, worked out, or removed within three years thereafter.

Pub. L. 94–377, § 13(a), Aug. 4, 1976, 90 Stat. 1090, provided that the repeal of this section is subject to valid existing rights.