6As from the appointed day, any sum borrowed or reborrowed before that date by the council of a rural district on the credit of any rate out of which special expenses of the council are payable shall be deemed to have been borrowed also upon the credit of any moneys from time to time received by the council under this Act and applicable for the purposes for which the loan was contracted, and any mortgage for the purpose of securing the repayment of any sum so borrowed with interest thereon shall have effect accordingly.