Michael, Thanks for your note. I found the image at a local flea market and didn't quite know what it was until I got home and did a little research - I did have a suspicion that it was Shakespeare's home.
Thank you! I will try the ferro sulfate again, but with more restrainer - the last time I tried, I got a foggy 'black rectangle' (underexposed and overdeveloped I think). Can you suggest a formula? Would it be your average collodion developer - or does it need adjustments?
Knowing you used iron is a great help, and something I can explore.
Nice to hear from you, Mike. I know the material you are speaking about, but unlike Terry, we have not done any research on it. We have always liked China and have between 2 and 4 small groups of material each of which possibly includes material by this same circle of late 1850s photographers working near Shanghai. You could have a look if you think it would be helpful.
BTW, we have a carte de visite of Ernest Lacan with an envelope (dated?) sent to Talbot when he stayed in a Parisian hotel. Would this possibly help your chronology?