Every conveyance or charge of, or upon, any estate or interest in lands, containing any provision for the revocation, determination or alteration of such estate or interest, or any part thereof, at the will of the grantor, shall be void, as against subsequent purchasers from such grantor for a valuable consideration, of any estate or interest so liable to be revoked or determined, although the same be not expressly revoked, determined or altered by such grantor, by virtue of the power reserved or expressed in such prior conveyance or charge.