Pennsylvania Statutes Title 72 P.S. Taxation and Fiscal Affairs § 5984. Lands on which personal property cannot be found may be sold for taxes two years due

All real estate within this commonwealth, on which personal property cannot be found sufficient to pay the taxes assessed thereon, and where the owner or owners thereof neglect or refuse to pay the said taxes, the collectors of the townships in which said lands lie shall return the same to the commissioners of the several counties;  and the said lands shall be sold as unseated lands are now sold, in satisfaction of the taxes due by the said owner or owners:  Provided, That no sale shall be made of such lands for the purpose aforesaid, until the owner or owners thereof shall have refused or neglected to pay the taxes aforesaid for the space of two years.