"Wood is heated in cylindrical iron retorts. the volatile materials are cooled, and while a portion remains gaseous and is used as fuel, a large part is condensed to a dark, tarry liquid." -Brownlee 1907
Brownlee, Raymond B., Fuller, Robert W., Hancock, William J., Sohon, Michael D., Whitsit, Jesee E. First Principles of Chemistry (Boston: Allyn and Bacon, 1907) 375
