Whenever any city of the first class of this Commonwealth shall be charged with the administration of any charitable use or trust for both the maintenance and education of orphans, it shall, without application to any court, act as guardian of the person and estate of each of such orphans, through the same agency that administers the charitable use or trust. In case any such orphan child, at or before the time said city is charged with the administration of such a charitable use or trust, or during the remaining time it acts as guardian of his estate, shall possess or become entitled to any effects or property, the said city shall be entitled, in like manner as other guardians, to demand and receive the same from any person having possession thereof, or owning the same, and to give acquittance therefor; and it shall be the duty of the said city to take care of the same as guardians, and to make the same productive as far as reasonably can be, and to deliver and pay over the same with the increase, less expenditures made in the exercise of a reasonable discretion, to the said orphan, on his attaining the age of 18 years, or to his legal representatives if he shall die before attaining that age.