Esther M. Lederberg: Degtekurs drove tar from birch bark

Why tar? Tar was used to lubricate wheel axles, locks, boots. Tar was used to make the lower logs in a log cabin water-proof. Tar was used in Russian black "yufti" (a skin specially constructed with a pleasant resinous odor) used in the manufacture of shoes and harnesses. Birch tar had many uses.