J.W. "Jack" Mitchell: someone you probably don't know. But Jack played a central role in establishing the modern theory of the silver halide process, expanding on the 1938 theory of Gurney and Mott.

Mitchell's expansive 1957 review "Photographic Sensitivity" (Rep. Prog. Phys., v20, pp433-515, 1957) described the entire silver halide photographic process for the first time with full detail given to the roles of electronic transitions, electron and hole trapping, and chemical and structural issues. His paper describes everything from sensitization to latent image formation, development, solarization, fogging, you name it. It is a thorough and authoritative masterpiece written at the very highest level. Mitchell's work strongly influenced the development of new emulsions and developing processes at Kodak, which partly supported his research here at the University of Virginia in the physics department.

I met Jack and learned about his work completely by accident. I am a faculty member at Virginia in the same department. As such you might think we'd have met formally. But he was long retired and I was junior, and it was a chance occurrence: I was arranging for a student to help Jack clean his house which was so full to the brim with papers that one couldn't even walk around!

Entering Jack's house, I noticed that he had many books and papers on the silver halide process, and he mumbled dejectedly, nobody cares about silver halide process anymore. I said, I beg to differ! I shoot film all the time!, and that is how we began.

Imagine how astounded I was to hear his tales about the early days at Kodak, his role in working through serious issues with latent image stability in commercial emulsions, his disinterest in lawyers and patents etc. Jack knew everybody in the field of photographic science and they knew him.

I found out that Jack did in fact still have a small lab and office in my department, which had been locked up for years; he'd been too sick (Alzheimer's) to care about it. I ventured into his little old darkroom and found a wealth of old plates, microscopes, papers, films, exotic potions, and carefully inscribed log books. I came to discover that Jack was theworld expert on the photophysics of the silver halide process, but he never had any interest in marketing his ideas or moving up any corporate ladder. Jack simply shared his results with Kodak, dutifully published his findings, and that was that.

Naturally, I met several times with Jack. His varying condition made our conversations amusingly scattered, but enjoyable to both of us. I thoroughly enjoyed our meetings.

I visited Jack for the last time last Friday; he was in the hospital here in Charlottesville, in a very weak condition. We chatted about the need for rest, and he dozed off and I left. A few days later, he passed away; I suppose he was 96 or so.

I left him regretting that I hadn't taken his picture while he was in somewhat better health. I'd wanted to take a portrait, a nice big, classic 8x10, and make a traditional print for the department to hang in some place of honour. But he was just too weak whenever we met, and it was all his caretaker could do to put him upright in a chair so that we could chat for a while.

Jack's contributions to the silver halide process should be remembered. And I will certainly remember his wonderful stories. Cleaning out his darkroom has been rather difficult... but also quite inspirational.

Further reading:

http://en.wikipedia.org/wiki/Latent_image