(2)Where a single sheet of paper, not being paper bearing an impressed hundi-stamp, is insufficient to admit of the entire instrument being written on the side of the paper which bears the stamps, so much plain paper may be sub-joined thereto as may be necessary for the complete writing of such instrument :Provided that in every such case a substantial part of the instrument shall be written on the sheet which bears the stamp before any part is written on the plain paper sub-joined.
