To the extent that such have not been heretofore exercised or discharged, all rights, powers, duties and liabilities of the Alabama Building Authority created by Act No. 205 of the 1955 Legislature, page 501, Acts of 1951, approved August 3, 1955, are hereby continued in full force and effect until such have been fully exercised and discharged. At such time as all of the rights, powers, duties and liabilities of the said Alabama Building Authority have been exercised or discharged, including specifically the payment or discharge of all bonds or other securities issued by such authority, the said authority shall perform the acts of dissolution prescribed by Section 18 of said act, and thereupon the said authority shall cease to exist.