The fat of the bear, used especially in medical and cosmetic preparations [OED] The website Victorian London says that 'In hairdressers' windows and over barbers' shops notices relating to bears' grease were perpetually seen, such as, "Bears' grease fresh this week"; "Bears' grease personally prepared" ; "Try our special Bears' grease." And less frequently, "We kill a bear this week." In the 1850s it was an article of faith that bears' fat nourished the scalp' and hair.

http://www.victorianlondon.org/publications5/londoners-10.htm

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