§ 85. Commissioner of taxation and finance custodian of fund. The commissioner of taxation and finance shall be the custodian of the state insurance fund; and all disbursements therefrom shall be paid by him upon drafts signed by the executive director, deputy executive director or an assistant director authorized for that purpose by the commissioners or by checks signed by one of such officers and by the commissioner of taxation and finance. He may deposit any portion of the state fund not needed for immediate use, in the manner and subject to all the provisions of law respecting the deposit of other state funds by him. Interest earned by such portion of the state insurance fund deposited by him, shall be collected by him and placed to the credit of the fund.