Section 28. Except as provided in sections eight and twenty-six, no stamp shall be affixed to, or impressed on,

28. Except as provided in sections eight and twenty-six, no stamp shall be affixed to, or impressed on, any bill of exchange, or promissory note, or any instrument chargeable hereunder with the duty of one anna, subsequent to the execution thereof, nor shall the provisions of sections twenty and twenty-four apply to any such instrument.