64 Pa. Stat. § 131
Where any warrants since the first day of April, 1784, have issued or hereafter shall issue from the land office, and hath not been or cannot be executed in the whole or in part, by reason that the lands therein described, or some part of them, have been previously appropriated by or for any other person or persons, according to law, or, having been executed, do interfere with some prior appropriation as aforesaid, the deputy-surveyor of the district or county shall, at the reasonable request of the party, his heirs, executors, administrators or assigns, certify to the Surveyor-General's Office whether any, and how much, of the lands in the said warrant described, hath not been or cannot be surveyed, for the reasons aforesaid, or being surveyed, doth interfere with any prior survey or appropriation; and the Surveyor-General, whenever he shall have proof of the same, shall, at the like reasonable request, certify to the Receiver-General the number of acres which shall remain unsatisfied on any warrant issued after the first day of April, 1784.
64 P.S. § 131