Something related to triboluminescense, I guess? I don't know if the light formed is enough to be visible as it is with many other substanced, but it doesn't take much energy to make developable defects in a silver halide crystal. Which we know very well, at they're light sensitive... Ole Tjugen > BTW, pressure effects on photographic emulsions has > evidently been widely studied. There is a mention of the > effect in _Theory of the Photographic Process_ 3rd edition, > Mees and James, with a number of citations to research > papers. The explanation given there is that the image is > produced by heat effects (see p.17), however I have a vague > recollection of an article attributing it to electron > release due to deformation of the crystal shell but have no > idea now where I saw this. ============================================================================================================= To unsubscribe from this list, go to www.freelists.org and logon to your account (the same e-mail address and password you set-up when you subscribed,) and unsubscribe from there.