(b)if on arrival of ganja at its destination, and deficiency in quantity (as compared with the quantity received at the source of supply) is found, a penalty, duty on such deficiency at such rates as may be prescribed shall be payable ; provided that the whole, or any portion, of such penalty, duty may be remitted, should the Excise Commissioner hold such deficiency to be due to dryage, vide Rule 164 below ; and