Special duty of excise imposed on excisable goods adds to existing duties and follows Central Excise procedural rules. Special duty of excise imposes an additional charge on goods already subject to duty under the Central Excises Act as a supplementary percentage of the amount chargeable, and is supplementary to duties under that Act or other laws; its levy and collection are to follow, as far as practicable, the provisions and procedural rules of the Central Excises Act, including refunds and exemptions, while excluding cases where a notification provides equivalent credit or reduction for duties already paid on inputs.