Comment 1 for bug 690208

That is merely the absence of a page. There has to be *something* opposite the last image in the book; the previous version of the BookReader used more of a rust or chestnut color, which looked kind of like an inside cover. The new version apparently uses white, which is probably not the best choice, as it does look like another (blank) sheet of paper.

You can see there's nothing there if you look at the book in 1up mode:

http://www.archive.org/stream/studiesobservati00krat#page/n235/mode/1up

No pages are available after the back cover.

I'll file a bug against BookReader suggesting a change in color.