It must be admitted that Prof. McKim knows more than the devil. Thanks for the valuable information, Prof. I really didn’t know about the inverted mirror and other procedures you mention. Nor did I know about the possible effect of an atmosphere polluted by sulphur dioxide and hydrogen sulphide. And concerning this, the various attempts at silvering I made in the chemistry lab of the high school in the city where I teach (physics), a very industrialised city. I will not attempt to silver again, but I will at least theoretically explore the topics presented by McKim, to whom I extend my thanks. Thanks also to those who have considered my intervention.
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