5c violet postal stationery envelope (H&G B13a) used with added 1915 5c slate blue 'Presidente' issue (SG 161) tied by ANCUD cds dated 18 JUL 1917 with second strike alongside. Ancud is the main P.O. on the Island of Chiloe. Addressed to OSORNO with arrival cds on reverse. Unusual late use of this envelope.