Explanatory notes
… - - Other 3825.50 - Wastes of metal pickling liquors, hydraulic fluids, brake fluids and anti-freeze fluids … it through a mass usually composed of bog iron ore or of hydrated iron(III)oxide, sawdust and calcium sulphate. This mass removes from the gas certain impurities (hydrogen sulphide, hydrocyanic acid, etc.). When spent, it …