As used in this chapter “United States” includes Alaska. “Acquired lands” or “lands acquired by the United States” include all lands heretofore or hereafter acquired by the United States to which the “mineral leasing laws” have not been extended, including such lands acquired under the provisions of the Act of (, 16 U.S.C., sec. 552). “Secretary” means the Secretary of the Interior, “Mineral leasing laws” shall mean the Act of (, 48 U.S.C., sec. 432); the Act of (, 30 U.S.C., sec. 181); the Act of (, 30 U.S.C., sec. 271); the Act of (, 30 U.S.C., sec. 281), and all Acts heretofore or hereafter enacted which are amendatory of or supplementary to any of the foregoing Acts. “Lease” includes “prospecting permit” unless the context otherwise requires. The term “oil” shall embrace all nongaseous hydrocarbon substances other than those leasable as coal, oil shale, or gilsonite (including all vein-type solid hydrocarbons).36 Stat. 96138 Stat. 74141 Stat. 43744 Stat. 30144 Stat. 1057March 1, 19111911-03-01October 20, 19141914-10-20February 25, 19201920-02-25April 17, 19261926-04-17February 7, 19271927-02-07