Ralph, where can I find out more about this?...
Fotch
I've shared one source in post #33, Ian listed another, and I think he explained why it is the case. Unfortunately, I cannot scan the Photo Techniques article as it would be a copyright violation, but I'm sure Martin Reed at Silverprint or Photo Techniques Magazine may be able to help.
However, I don't think this is a new discovery.
If you have HT2 and access to soft and hard water, you could do your own test.

and it was destroyed 