The accumulated surplus and unallocated reserves of an association at the time of conversion to a stock association shall be designated as a permanent loss reserve against which any losses incurred on assets may be charged. In case of liquidation the remaining sum in said permanent loss reserve shall be distributed to the depositors in proportion to the withdrawable value of their deposit accounts at the time of liquidation. In liquidation, after payment of all liabilities and the withdrawable value of all types and classes of deposit accounts together with the remainder in the permanent loss reserve heretofore mentioned, any excess shall be paid pro rata to the stockholders.