1911 (ed. 8) 922/2 (heading) Army Pill No. 9.
1917 A. G. Empey 301 ‘No. 9.’ A pill the doctor gives you if you are suffering with corns or barber's itch or any disease at all.
1946 J. Irving 123 Number-nine Boatswain, the Warrant Wardmaster. As ‘King of the Sick Berth Staff’ this allusion to the No. 9 pill is not inappropriate.