The commissioner may by order authorize any bank or banks to receive new deposits, which new deposits shall be special deposits and designated as such, shall be segregated from all other deposits and may be invested only in assets approved by the commissioner as being sufficiently liquid to be available when needed to meet any demands on account of such special deposits, which assets shall not be merged with other assets but shall be held in trust for the security and payment of such special deposits, except that income from such assets may to the extent authorized by the commissioner be used by the bank for other proper purposes of the institution, and the withdrawal of such special deposits shall not be subject in any respect to restriction or limitation under this chapter.