The general mining laws of the United States so far as they are applicable to placer-mining claims, as prior to May 4, 1934, extended to the Territory of Alaska, are declared to be in full force and effect in said Territory: Provided, That nothing herein shall be held to change or affect the rights acquired by locators or owners of placer-mining claims prior to May 4, 1934, located in said Territory under act August 1, 1912 (37 Stat. 242, 243) and amendatory act March 3, 1925 (43 Stat. 1118).