Where lands are acquired by the corporation under the exercise of eminent domain, but are not required for its purposes, the corporation, within the prescribed period, or if no period is prescribed, within ten years after the expiration of the time limited by the charter for the completion of the works, shall absolutely sell and dispose of all superfluous lands and apply the purchase money arising from the sale to the purpose of the charter, and in default thereof, all superfluous lands remaining unsold at the expiration of this period, shall thereupon vest in and become the property of the owners of the lands adjoining thereto in proportion to the extent of their lands respectively adjoining the same.