72 Pa. Stat. § 4731
All mortgages, judgments, recognizances and moneys owing upon articles of agreement for the sale of real estate made and executed after the passage of this act, shall be exempt from all taxation except for state purposes; and from and after the first day of December next no taxes of any description shall be assessed or collected except for state purposes, on or from mortgages, judgments, recognizances or moneys owing upon articles of agreement for the sale of real estate, whether made and executed before or after the passage of this act: Provided, That nothing in this act shall be construed to apply to mortgages, judgments or articles of agreement given by corporations: Providing, That this act shall only apply to the counties of Berks, Schuylkill, Luzerne, Clearfield, Allegheny, York, Delaware, Montgomery, Chester, Lancaster, Huntingdon, Fulton, Bedford, Blair, Lebanon, Clinton, Carbon, Monroe, Lehigh, Mifflin, Westmoreland, Northampton, Juniata, Somerset, Indiana, Greene, Elk, Forest, Franklin, Perry, Cumberland, Dauphin, Lawrence, Lycoming, Union, Snyder, Erie, Crawford, Bucks, M'Kean, Fayette, Philadelphia and Mercer.
72 P.S. § 4731