Abandoned tar factory. Gas storage tanks are seen at left. Some tars are natural by-products of the petroleum industry, while others (coal-tars) are a by-product of the industry that converted coal and other fossil fuels to fuel gases. Tars can be used and further processed to obtain other chemicals. Such industrial sites can contaminate the water and the soil if they are not properly cleaned up. Photographed in Bootle, Merseyside, England.