A couple years ago I put a pdf of "Photographic Emulsions" by E. J. Wall, 1929, on my web site for download. I have a better copy up there that can be downloaded now at:
It's 12.5 Megs in size, but the graphics and text are much better in quality that the previous pdf I had made.
If you have the previous version I put up there, I highly recommend downloading the new one.
If you don't have this book, it's one of the classics in the field of emulsion making and well worth reading for a historical perspective.