No money shall be drawn from the Treasury nor shall any obligation for the expenditure of money be incurred, except pursuant to appropriations made by the Council. No warrant for the payment of any claim shall be issued until such claim shall have been approved in writing by the Director of the department or commission for which the obligation was incurred. Each Director of a department and his surety shall be liable to the Municipality for all loss and damage sustained by the Municipality by reason of the unfaithful approval of any claim against the Municipality in his department. The Director of Finance shall have power to require evidence that the amount of the claim is justly due and is in conformity to law and ordinance, and for that purpose he may summon before him any officer, agent or employee of any department of this Municipality, and examine him upon oath of affirmation relative thereto.