They very nicely wrote back:
Volume #8 of Girl Genius ran online from February 4, 2008 to November 19, 2008.
Here's a link directly to the first page of Volume #8:
The easiest way to navigate around is using the drop-down list of chapter headings at the bottom of the comic. We've got the volumes' beginning and ending pages marked throughout the list.
Thanks for reading!
Assistant to the Professors