40.(1) When the Collector impounds any instrument under section 33, or receives any instrument sent to him under section 38, sub-section (2), not being an instrument chargeable with a duty of ten poisha or five poisha only or a bill of exchange or promissory note, he shall adopt the following procedure:- (a) if he is of opinion that such instrument is duly stamped or is not chargeable with duty, he shall certify by endorsement thereon that it is duly stamped, or that it is not so chargeable, as the case may be: (b) if he is of opinion that such instrument is chargeable with duty and is not duly stamped, he shall require the payment of the proper duty or the amount required to make up the same, together with a penalty of five Taka or, if he thinks fit, an amount not exceeding ten times the amount of the proper duty or of the deficient portion thereof, whether such amount exceeds or falls short of five Taka: Provided that, when such instrument has been impounded only because it has been written in contravention of section 13 or section 14, the Collector may, if he thinks fit, remit the whole penalty prescribed by this section. (2) Every certificate under clause (a) of sub-section (1) shall, for the purposes of this Act, be conclusive evidence of the matters stated therein. (3) Where an instrument has been sent to the Collector under section 38, sub-section (2), the Collector shall, when he has dealt with it as provided by this section, return it to the impounding officer.