The state treasurer is hereby directed to set aside from the primary road fund the sum of five hundred thousand dollars to be known as the primary road contingent fund. [C24, §4703; C27, 31, 35, §4755-b17; C39, § 4755.17; C46, 50, 54, 58, 62, 66, 71, 73, 75, 77, 79, 81, §313.17 ]