I use a wide range of dyes in my work, as biological stains, and there is a
persistent story which is circulated concerning one of the dyes, called
Gentian Violet.  It seems this dye was manufactured by a number of
companies, but for unknown reasons, the product produced by a particular
German company was far superior to that from any other manufacturer.  Some
representatives of an American dyestuffs company visited the German plant to
observe their production methods.  As they passed by one of the production
areas, they happened to see a workman urinating in the vat where the dye was
being produced, rather than taking the time to walk to the facilities at the
other end of the plant.  Well, it turned out that was the magic ingredient.
Specifically, the factor which made the difference was nitrogen; and urea,
which is found in mammalian urine, was a ready source of nitrogen.  Urea is
still used today in the manufacture of that dye and several others - only
now it is added in a more sanitary manner.

Paul M.