My brain is tired, yo.
I just spent a chunk of time taking notes on a bunch of different early photographic techniques: daguerreotypes, calotypes, tintypes, ambrotypes, the wet-plate colliodion process, the dry-plate gelatin emulsion, albument prints, etc. My notes are a festival of chemical terms I haven’t used since high school: silver nitrate, potassium bromide, pyrogallic acid. And I’m not yet done; now that I have all this stuff noted down, I need to figure out just how I’m going to use it in the context of the story.
What I wonder — and what my sources don’t tell me — is the extent to which the proliferation of substances and techniques was guided by an understanding of the chemistry behind them, and to what extent it was simple trial and error. I wonder what happens if I add honey into the collodion to slow its drying? What if I add beer instead? The book I’m reading points out that these things are hygroscopic, but it doesn’t say whether that was a known characteristic at the time. I think it must have been, but maybe not; guncotton (a key element of collodion) was invented when a guy used his apron to mop up nitric acid, and then his apron exploded. (Not while he was wearing it, fortunately.) Knowledge of chemistry advanced remarkably between A Star Shall Fall and this book, but that doesn’t mean they weren’t still discovering things through sheer dumb chance.
(Skills I have acquired in the writing of this series: it occurred to me I could look up “hygroscopic” in the OED to get a sense of the term’s development. It doesn’t seem to have been used in quite that manner until 1875, a good decade after the experimentation with honey et. So while the quality itself may have been recognized, it wasn’t something they were talking about in those terms — not yet.)
It’s phenomenal, though, watching the speed with which technology developed. Not quite as fast as (say) digital photography has developed today, but still pretty amazing, given the tools they had to work with. And the results are amazing, too; there aren’t a lot of photographs I can use in researching the book — what I really want are London street scenes, and those are vastly outnumbered by a) portraits and b) cartes-de-visite of random foreign landmarks — but dude. There are photographs of my period. It’s the clearest sign I have of how this book stands on the threshold of the modern age.