72 Pa. Stat. § 5891
After the passage of this act, all surplus bonds given by purchasers at tax sales of real estate shall be acknowledged by the obligor or maker before any officer competent to take acknowledgment of deeds, after which they shall be deposited with the county treasurer before the deed for the land upon which such surplus bond is lifted by the purchaser. It shall be the duty of the county treasurer to have all such surplus bonds deposited with him, forthwith recorded in full in the office of the prothonotary of the court of common pleas of the county wherein the lands sold lie, and the prothonotary shall provide a book or books at the expense of the county, to be entitled "Surplus bond record," in which shall be indexed in alphabetical order in the name of the purchaser or obligor who gave the bond, with the amount and date of the same, and after record of said surplus bond the same shall be filed in the prothonotary's office as is now provided by law.
72 P.S. § 5891