64 Pa. Stat. § 420
So much of the act of March 11, 1843, being the fourth section of said act, as declares that all patents granted by the commonwealth do pass and vest the entire estate of the commonwealth to and in the patentees, free and clear of all liens, incumbrances and claims of the commonwealth whatsoever, prior to the date of the respective patents, except for arrearages of purchase money, shall not be taken or construed to interfere with the rights of actual settlers, or to extend to lands that may have been escheated to the commonwealth; and it is hereby declared, that the pre-emption right of actual settlers under existing laws of this commonwealth, or under any law or laws that may have been repealed by the said fourth section herein, referred to, shall in no wise be impaired in any suit of law now pending or hereafter to be instituted by patentees, on patents issued since the passage of the said fourth section.
64 P.S. § 420