It shall be lawful for the city of Philadelphia, as rapidly as purchasers can be procured, without a sacrifice of price, to make public sale and conveyance of the public halls, lots and real estate vested in the said city, not held upon any trust and not required for authorized public purposes, and to apply the proceeds in discharge of the city debts, and if the ground-rents be reserved, to sell and convey the same for said purposes.
53 P.S. § 16260