On one hand, we want to get rid of <sup> tags as much as possible. On the other, this makes markup problematic, as the material will be "aforesaid oil" — will this get associated with "oil of sulfur" in the markup vocabulary normalization? NB: there is an editorial comment explaining that "aforesaid oil" is oil of sulfur.
Hmmm...well, we have two competing goals: when searching to capture all instances of a material, and to remove sups. In this case, I don't see the harm in leaving the suped "of sulfur", and deleting the ed note.