It shall be the duty of the commissioner of forestry¹ to inquire into and examine the location and character of unseated lands advertised by the respective county treasurers and the county commissioners of this commonwealth for sale for the nonpayment of taxes, and if in his judgment the same are so located and are of such a character as to make them desirable for the commonwealth for the purpose of creating and maintaining a forestry reservation, he shall have power, at his discretion, to purchase any such lands for and in behalf of the commonwealth at such tax sales, subject to the right of redemption under existing laws: Provided, however, That the bid made and the price paid for said lands shall in no case exceed the amount of taxes for the non-payment of which the same are being sold, and the costs. For all purchases so made in behalf of the commonwealth, the auditor general shall draw his warrant upon the state treasurer to the order of the county treasurer, upon certificate filed by the commissioner of forestry with the said auditor general: Provided further, That the commissioner of forestry shall have power to purchase unseated lands other than such as are advertised for sale for the non-payment of taxes, upon such terms and conditions as may be agreed upon with the owners of such land: Provided, That such purchase shall be approved by the governor and the board of property, consisting of the attorney general, secretary of the commonwealth, and secretary of internal affairs. And provided further, That in no case shall the price paid for such unseated land exceed the assessed value of the same. For all purchases so made in behalf of the commonwealth the auditor general shall draw his warrant upon the state treasurer to the order of the grantor, upon certificate filed by the commissioner of forestry, with approval as aforesaid: Provided, That in no case shall the amount paid for any tract of land purchased under the provisions of this act exceed the sum of five dollars per acre.