Pam Marks, age 13, of Erie, Pa., for her question:

WHAT IS COAL TAR?

Coal tar is a thick, sticky black liquid that is obtained as a byproduct in the manufacture of coke and coke oven gas from soft coal.

Coal tar is formed by partially condensing or changing to liquid the hot vapors from a coke oven or a coal gas producer. Further condensation of the vapors produces light oils, such as benzene and toluene.

Benzene is used as a solvent and in making perfumes and some gasolines. Toluene is used in the making of dyes, paints, explosives and antiseptics.

Tar acids such as carbolic acid and tar bases such as aniline are other coal tar products. Carbolic acid and aniline are used to make dyes.

Creosote and pitch are heavy liquid coal tar products. Creosote preserves wood and pitch is used 1n the manufacturing of roofing materials and paint.

Petrochemicals, or chemicals made from petroleum, are now replacing coal tar chemicals in industry and chemistry.