Section 4
SEC. 4. Any balance left over after the purchase or construction of the electric light, heat, and power system provided for in section one hereof is hereby constituted a reimbursable fund, to which shall be added all receipts of the plant on account of sales of electric current, to cover the expenses of operation and maintenance of the system, and any balance over the expense of operation and maintenance may be expended in further extension and improvement of the property or may be credited to the Insular Treasury to reimburse the Government for the cost of the purchase or construction.