In the Middle Ages it was the "tanner". "Tan" was the urine. Those collected after the curfew, the tanner on the premises (the operator guests assembled, the liquid gold for this purpose.) Since the tanned skins of the tannin urine according stank, tanner, the gates of the city banned before. Thus it was in raids also the first who had to believe in it!
(Sent from: Norman Löhr)