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_Adulteration of Nitrate of Silver._--Will any of your chemical readers
tell me how I am to know if nitrate of silver is pure, and how to detect
the adulteration? _If so_ with nitrate of potash, how? One writer on
photography recommends the fused, as then the excess of nitric acid is
got rid of. Another says the fused nitrate is nearly always adulterated.
I fear you have more querists than respondents. I have looked carefully
for a reply to some former Queries respecting MR. CROOKES's restoration
of old collodion, but at present they have failed in appearance.