[Sca-cooks] Leven: yeast or sourdough?

[Johnna Holloway]

Another entry on barm in OED.
This time as a verb-
and "Obs. or arch."
    1. To mix with yeast; to leaven, ferment.

  1616 SURFL. & MARKH. Countr. Farm 589 Your best ale must be barmed  
as soone as it is coold.
     2. To rise in froth or fermentation.

c1440 Promp. Parv. 32/2 Bermyn, or spurgyn as ale, spumo.

Johnnae