It shall be unlawful for any public utility, directly or indirectly, to acquire or dispose of any utility assets situated within the Commonwealth or any utility securities of any other company unless such acquisition or disposition shall have been authorized by the Commission. If and when so authorized by the Commission, any public utility may acquire or dispose of any such utility assets or utility securities; but no such authorization by the Commission shall confer upon any county or municipality authority, other than that otherwise conferred by law, to acquire or to dispose of any utility assets or utility securities.