Heading 06 : In mining, a horizontal passage or drift of a tunnel, also the end of a drift or gallery. In tanning, a layer of ground bark over the tanning liquor.
Barbara A. Plog, Patricia J. Quinlan, Jodey B. Schonfeld and Patricia M. Dewey (editors), Fundamentals of industrial hygiene 5th ed., Appendix E - Glossary (Michael Horowitz, MS, CIH - Compiler), National Safety Council, Illinoise, USA 2002. http://www.wbcsd.org/web/projects/cement/tf3/fihAp pendices.pdf, (Env and Occupn Sfty and Hlth - Amer) {680}
