I have revised the glossary to read: feather alum (a mineral; possibly spalt, spar, or asbestos). Cotgrave has <i>Alun de plume</i> as "stone allum" or "itching powder," which can be steeped, pounded, and spun into thread to make long-burning candle wicks and matches.
I have suggested in comment tracking that we delete the comment on 107v.