(1) Such knowledge or waiver of inquiry shall, in the absence of evidence to the contrary, be presumed if the legatee has enjoyed for two years the benefits provided for him by the will without doing any act to express dissent.
     (2) Such knowledge or. waiver of inquiry may be inferred from any act of the legatee which renders it impossible to place the persons interested in the subject-matter of the bequest in the same condition as if such act had not been done.
     Illustration
     A bequeaths to B an estate to which C is entitled, and to C a coal-mine. C takes possession of the mine and exhausts it. He has thereby confirmed the bequest of the estate to B.