Whenever the mayor of any city of the second class shall certify in writing to the council of said city that, in his opinion, an emergency exists, and a resolution of said council to that effect shall be duly enacted in the manner provided by law, the said city shall appropriate such sum or sums of money as may, from time to time, be considered necessary and advisable, to purchase the necessities of life, including food and coal.

All matters relating to the purchase thereof, the storage, sale or disposal thereof, shall be under the control, direction, and supervision of the Department of Supplies, subject to such rules and regulations as may be prescribed by the council of said city or the department. The prices to be charged for said necessities of life, including food and coal, shall be such as to return to the city upon the entire transaction as near as may be the actual cost to the city of the purchase, storage, and disposal of the said necessities of life.