[dwross]

Some additional thoughts expressed before.

1. The book does not clearly state when active or oxidized gelatins are used for the makes. This makes speed, fog, and contrast variations difficult to evaluate, especially if you move on to the sensitization chapter.

2. The use of colloidal Iodide in the sensitization chapter was in large part misunderstood in that day and age. The Iodide effect was a bit different than what they observed and is used today in most all Kodak emulsions, as the second step rather than at the end of the make due to the latest revised understanding. And, many emulsion makers today say that adding Iodide like this should cause renucleation, but it actually does not if the process is carried out properly.

So, I can say that for beginners, this is a good book but rather dated with information that has changed over the years with better explanations and also I can say that this book starts out by leaving a lot of things out. Burt Carroll was a friend in my early years at Kodak, and just after he had retired. I have had a chance to discuss some of these things with him in the 70s. I think that he would write a totally different book today. I wish I had the resources to write a fully revised edition of his book.

The accepted wisdom today is to dissolve salts in the kettle and add dry gelatin. Then stir while raising temperature. OR....
Add dry gelatin to cold water and stir while raising temperature, then add salt. The latter method is quicker and is currently used. No ions but K, Na and NH4 are used as halide salts when making emulsions. All other positive ions in the kettle as halide salts have bad effects except for a few used at low concentration such as Cd, Cu, Hg, Ir, Os and Rh. These are listed in decreasing useful concentration and they do not work equally well in all emulsions. Cu and Hg are used mainly for toning to get warm toned emulsions.

PE

I am very much looking forward to the first graduate student who researches the history of gelatin with the characteristics of the myriad of brand names available at one time. Until then, for my purposes and interests in photographic emulsions as an historical process, I'm not finding the 'gelatin issue' a stumbling block.

I would hope that Burt Carroll would write a different book today! That's the nature of science. If you wrote a revised edition, I would hope that someone would revise it 80 years from now . And each edition would be a valuable addition to the library of an historian of emulsion making. I have three editions of Fundamentals of Photographic Theory by James and Higgins. All of them have valuable information. The same is true for the four editions of The Theory of the Photographic Process, first by Mees, then by Mees and James, and finally by just James.

'And, many emulsion makers today say that adding Iodide like this should cause renucleation, but it actually does not if the process is carried out properly.'
That sounds like it's a book all of its own. Actually, that's the kind of opaque statement that's a pretty strong motivation to dig into the literature.

I'll add a short note for the non-chemists who would like to join this 'book club'. Halides (at least the ones we care about) are chloride (Cl), bromide (Br), and iodide (I). They combine with potassium (K), sodium (Na) and NH4 (ammonium ion). The combinations are 'salts'. NaCl, sodium chloride, is common table salt. The halides combine with the silver in silver nitrate (AgNO3) to form silver halides, sometimes noted as AgX. The silver halide is the photosensitive constituent of the emulsion.