21 Pa. Stat. § 45
Where there is no subscribing witness to any deed and conveyance, or other instrument of writing, concerning lands, tenements or hereditaments, which might be recorded if probated according to existing laws, and any of the parties thereto shall be deceased, it shall and may be lawful to and for any of the judges of the supreme court, or any judge, learned in the law, of the court of common pleas of the county where the lands lie, to take the examination of any witness or witnesses, on oath or affirmation, to prove the handwriting of such deceased party or parties, and of the surviving party or parties which shall be certified by the judge before whom such proof shall be made; and such deed, conveyance or other instrument of writing, being so proved by two or more witnesses, and so certified, shall be recorded as in other cases under the acts relating to the recording of deeds: Provided, That in addition to the proofs so made by two or more witnesses the surviving party or parties to such deed, conveyance or other instrument of writing, shall also be examined, on oath or affirmation, before said judge, as to the handwriting of such deceased party.
21 P.S. § 45