1)  Photographic Emulsion Technique, 2nd Ed., 1948, by T. Thorne Baker.  Highly recommended.

2) The Darkroom Cookbook, 2nd Ed, by Stephen G. Anchell.  The chapters on handling chemicals are a must-read. 

3)  SPSE Handbook of Photographic Science and Engineering, Edited by Woodlief Thomas, Jr., 1973.

4)* The Dictionary of Photography, by E. J. Wall, 1912. Google Read

5)* Photography with Emulsions, by William De W. Abney, 1885 (a Elibron Classics reprint).  Google Read

6)* Photographic Emulsions: Their Preparation and Coating on Glass, Celluloid and Paper, Experimentally, and on a Large Scale, by E. J. Wall, 1929. (Available as a UMI Books on Demand bound reprint.)  Note: Even as a reprint this is expensive and it's more for the historical tone than easily useful info. That said, I believe the experience of swimming in the time stream is invaluable to mastering a historical process.  Kirk Keyes has posted a very readable copy on his website.

7)  Making and Coating Photographic Emulsions, by V. L. Zelikman and S. M. Levi, 1964.  (a UMI Books on Demand bound reprint.  Note: This book is serious chemistry.  It's mostly over my head, but I keep chewing away at it, a page at a time. I think it's probably excellent. 

8)  The Encyclopedia Britannica, 1911, Vol. XXI, PAYN to POLKA (i.e. Photography).

9)  The Focal Encyclopedia of Photography, McGraw-Hill Book Company, 1969.   

10)  Silver Gelatin, by Martin Reed and Sarah Jones, Amphoto Books, 1996.   This is really about using Liquid Light or the other prepared emulsions, but there is a bunch of solid information for the person who may not have an extensive darkroom background.  In addition, there are a number of emulsion recipes from original publications, primarily Baker and Wall.  This book is currently on the used book market and very expensive.  If you have a limited book budget, it is not the first place to put your money.  There may be a new edition in the works.

11)* Practical Color Photography, by E. J. Wall, 1928.  Google Read

12)  Photographic Science, by Earl N. Mitchell, 1984.

13)  History of Color Photography, by Joseph S. Friedman, 1947.

15)  Photographie mit Bromsiber-Gelatine, by Josef Eder, 1890. (in German)

16)  Successful Negative Making, 2nd Edition, by T.Thorne Baker, Focus Photographic Manuals No.1, 1905.  This booklet doesn't have any emulsion recipes, but rather speaks to the best ways to handle the commercial plates of the (1905) day, and is therefore a gold mine of practical information for working with our own plates.  My copy is very fragile and can't be opened fully for scanning, so I will be slowly transcribing it onto the Light Farm.

17)* Modern Dry Plates, by J. M. Eder, 1881.  Google Read

18)  Memoirs of a Photochemist, by Dr. Fritz Wentzel, published by the American Museum of Photography, 1960.  Although this doesn't contain much technical info, it is one of my favorite 'good reads', — a delight and nearly as good as time travel.

19)* Dye Transfer Materials, by James Browning. pdf File

20)* The Photographic Emulsion, by B. H. Carroll, Hubbard, and Kretschman, The Focal Press.  This book is in the process of being scanned into The Light Farm. To check out its progress, go here.

21) The Theory of the Photographic Process, Third Edition, by C.E. Kenneth Mees and T.H. James, 1966.

22)  The Negative, by Ansel Adams,  (New York Graphic Society, 1948).

23)  Introduction to Photographic Theory – The Silver Halide Process, by B. H. Carroll,  Higgins and James,  (Wiley and Sons, 1980).

24)  Photographic Facts and Formulas, by John S. Carroll, Wall and Jordan,  (Prentice-Hall, 1975).

25)  Photographic Emulsion Chemistry, by G. F. Duffin, (The Focal Press, 1966).

26)  History of Color Photography, by Joseph. S. Friedman,  (American Photographic Publishing Company, 1947).

27)  The Theory of the Photographic Process, Third Edition, by T. H. James, editor,  (The Macmillan Company, 1966).

28)  Fundamentals of PhotographicTheory, by T. H. James and George C. Higgins,  (John Wiley & Sons, 1948)

29)  Fundamentals of PhotographicTheory,2nd Edition, by T. H. James and George C. Higgins,  (Morgan & Morgan, 1960).

30)  Fundamentals of Photographic Theory, 2nd Edition, 2nd Printing, by T. H. James and George C. Higgins,  (Morgan & Morgan, 1968).

31)  Manual of Photography, by M. Carey Lea,  (Benerman and Wilson, 1868) REPRINT.

32)  Photographic Processing Chemistry, L. F. A. Mason,  (The Focal Press, 1966).

33)  From Dry Plates to Ektachrome Film, A Story of Photographic Research, C. E. Kenneth Mees,  (Ziff-Davis Publishing Company, 1961).

34)  The Theory of the Photographic Process, by C. E. Kenneth Mees,  (The Macmillan Company, 1945) and the Second Edition, 1954.

35)  Fundamental Mechanisms of Photographic Sensitivity, Proceeding of a Symposium held at the University of Bristol in March 1950,  N. F. Mott (Chairman),  (Butterworth's Scientific Publications).

36)  Gelatin in Photography, Volume I, Monographs on the Theory of Photography, from the Research Laboratory of the Eastman Kodak Company, No. 3,  by S. E. Sheppard, (D. Van Nostrand Company, 1923).

37)  Investigations on the Theory of the Photographic Process, by S.E. Sheppard,  (The Focal Press, 1969).

38)  Dry Plate Making for Amateurs: A Series of Articles First Published in The Photographic Times,  by George Law Sinclair, (Scovill Manufacturing Company, 1886) REPRINT.

39)  The Silver Bromide Grain of Photographic Emulsions, Monographs on the Theory of Photography, from the Research Laboratory of the Eastman Kodak Company, No. 1, by A. P. H. Trivelli and S. E. Sheppard,  (D. Van Nostrand Company, 1921).