Interest on a fund belongs to the fund; exception

Whenever the treasurer receives interest on funds belonging to the Commonwealth or to any political subdivision thereof, such interest shall become a part of the principal of the particular fund on which such interest accrued and shall be accounted for by the treasurer in the same manner as he is required by law to account for the principal. However, the governing body of any county or city may direct that the interest received from general obligation bond proceeds invested be credited to the general fund of such county or city. Any treasurer violating this section shall be deemed guilty of a Class 1 misdemeanor.