Saving old negatives

I realise that this enquiry is not in the direct thread of alt processes but
I'm hoping that someone out there can help me. I have a fairly large number of
old glass negatives, these are in the region of 100 years old(No, I didn't
take them myself). The problem I'm having is with "silvering" of the image.
       I have tried using a proprietary tarnish remover on a few with some
success, but am a little nervous of subjecting the rest of them to the same
treatment. What I would appreciate is any advice on restoring these negs without
risking irreversible damage.

Irving Young, Lancashire, UK.
Received on Wed Apr 5 11:52:51 2006