Excise exemption for Chapter 68 goods containing high fly ash or phosphogypsum removes duty when composition threshold is met. Exempts from the whole of the duty of excise all goods falling within Chapter 68 of the Central Excise Tariff that contain more than the prescribed proportion by weight of fly ash or phosphogypsum or both, pursuant to powers under the Central Excise and Salt Act, 1944, and superseding an earlier notification.