If any instrument chargeable with duty and not duly stamped, not being an instrument chargeable with a duty of 1 [twenty paise] or less is produced by any person of his own motion before the Collector within on year from the date of its execution or first execution and such person brings to the notice of the Collector the fact that such instrument is not duly stamped and offers to pay to the

Collector the amount of the proper duty, or the amount required to make up the same and the Collector is satisfied that the omission to duly stamped such instrument has been occasioned by accident, mistake or urgent necessity, he may, instead of proceedings under section 33 and 39, receive such amount and proceed as next hereinafter prescribed.