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.