A cross-post, but for the sake of completeness in the silver gelatin forum, APUG member piticu just mentioned in another thread that The Theory of the Photographic Process by C E Kenneth Mees is up for reading at http://www.archive.org/details/TheTh...graphicProcess

I have no idea if this is an essential book or not - just passing the info from this thread http://www.apug.org/forums/forum56/9...ence-book.html further.