Non payment of excise duty on plain tamarind kernel powder declared permissible where administrative practice led to non levy. The Central Government, satisfied that a generally prevalent practice resulted in non levy of excise on plain (un modified) tamarind kernel powder under the relevant tariff heading for the identified period, directs under section 11C that the whole of the duty payable under section 3 but for that practice shall not be required to be paid in respect of those goods for which duty was not levied during that period.