From and after passing of this act, all other lands belonging to this commonwealth, and within the jurisdiction thereof, and lying north and west of the rivers Ohio and Allegheny, and Conewango creek, excepting such parts thereof as heretofore have been or hereafter shall be appropriated to any public or charitable use, shall be and are hereby offered for sale to persons who will cultivate, improve and settle the same, or cause the same to be cultivated, improved and settled, at and for the price of seven pounds ten shillings for every hundred acres thereof, with an allowance of six per centum for roads and highways to be located, surveyed and secured to such purchasers, in the manner hereinafter mentioned.