Nothing in this act shall extend or be construed to extend to give validity to any grant, warrant or location issued after the fourth day of July, 1776, for any lands or lots within ten miles of the city of Philadelphia, or within three miles of any county town in this state, or to any warrant, grant or location for a greater quantity of land than five hundred acres in one tract, or to any lands or lots not granted in the usual forms of the land office, or to lands not within the Indian purchase, anything herein contained to the contrary in any wise notwithstanding.