Page 59 of the FDC 3rd paragraph of the block titled Agfa Rodinal - Bill Troop states that "Potassium Bromide has also been added, which would not be necessary if p-Aminophenol was the sole developing agent"
Originally Posted by Photo Engineer
I have the same formula as Bill publishes in the FDC in many books, and Dr Momme Andresen published it in an Agfa publication himself, it's often listed as a Paramidophenol single solution developer, which is Agfa's original name for p-Aminophenol.
No-one doubts the formula is close to Rodinal, but no book I have other than the FDC/DCB states it's the original Rodinal, in fact none even use the word Rodinal.
J.Desalme & others state that Rodinal type developers use the free base rather than the hydrochloride. Desalme is likely to have been well informed, he was researching similar developing agents to Andresen including phenylene diamines, aminophenols, and disclosed Pyramidol as a developing agent in 1912. (His first research papers are from the1890's).
A 1912 research paper from Cornell University, quotes from work done by Sheppard and Mees (1907 so pre-Kodak) indicating that p-Aminophenol developers aren't suppressed by high levels of Bromide. So there's no reason what so ever why a high level of Bromide can't be present in modern Rodinal purely to suppress fog caused by the higher level of Hydroxide.