Tar, ammonia, naphthalene and coke were some of the by-products that derived from the several processes of the gas production line. However, mind you that all these by-products were exploited. The Athens Gasworks didn’t waste anything. These by-products were used as raw materials by other industries: the tar was used in insulating- waterproofing materials and in the road construction, the ammonia in the pharmaceutical industry and the coke was used as fuel for factories and homes. Even the graphite that was formed inside the retorts was made into pencils!