Back in 2012 I was looking for confirmation of a cancel involving a likely Chicago Board of Trade firm with the initials BF&Co. Turns out there were two major firms during the 1898 period with those initials: Barrett, Farnum & Co., and Bartlett, Frazier & Co. The 2012 post shows a standard issue Barrett, Farnum cancel with the firm's name spelled out. Also displayed was a fancier BF & Co initial cancel, which I couldn't confirm was linked to Barrett, Farnum.
David Thompson has a found a Bartlett Frazier sale memo showing that the fancy initials belong to that company. Problem solved!