4. Rebate of duty on alcohol, etc., supplied for manufacture of dutiable goods. -Where alcohol, narcotic drug or narcotic had been supplied to a manufacturer of any dutiable goods for use as an ingredient of such goods by or under the authority of, the collecting Government and a duty of excise on the goods so supplied had already been recovered by such Government under any law for the time being in force, the collecting Government shall, on an application being made to it in this behalf, grant in respect of the duty of excise leviable under this Act, a rebate to such manufacturer of the excess, if any, of the duty so recovered over the duty leviable under this Act.