Naphthalene is available in the form of vapour which condenses directly to a solid, chemically neutral aromatic material. The raw coke has a naphthalene concentration of 50 – 55°C thereby leaving no naphthalene when the gas is quenched to 80 – 84°C. Naphthalene mixes very easily in tar. As a general principle it is necessary to reduce the naphthalene in gas concentration corresponding to a dew point temperature appreciably below any which may be experienced by the walls of the gas distribution pipework.