Tegrin

Coal tar is a thick dark liquid which is a by-product of the production of coke and coal gas from coal.[2][3] It has both medical and industrial uses.[2][4] Medicinally it is a topical medication applied to skin to treat psoriasis and seborrheic dermatitis (dandruff).[5] It may be used in combination with ultraviolet light therapy.[5] Industrially it is a railroad tie preservative and used in the s... [wikipedia]