Nothing contained in this act shall be construed to authorize the city to invest moneys of a charitable use or trust in any such common trust fund contrary to any specific limitation or restriction contained in the will, deed or other instrument by which any real and personal property are given, granted, conveyed, bequeathed, devised to, or otherwise vested in, the city upon charitable use or trust, nor to limit or restrict the authority conferred upon the city with respect to investments by any such instrument.
53 P.S. § 5508