NNP

Warner Talso asked for recommendations of book on the chemistry of coins. You cited Weimar White's book, and while I can't find my copy, and thus don't want to offer criticism of it, my recollection is that I did not find it useful.

There are very few single volumes on the deterioration of coinage alloys and their conservation. The one I can recommend with enthusiasm is also an oldie: Gerhard Welter, "Die Reinigung und Erhaltung von Muenzen und Medaillen" (The cleaning and conservation of coins and medals). I have the fourth expanded edition of 1970, published by Klinkhardt and Biermann in Braunschweig, Germany. There is an English translation published in the 70's by Hans Schulman but it is highly abridged, and I do not recommend it.

The German edition that I use is a 124 page paperback, just crammed with concisely presented information in its nine major sections and ca. eighty subsections. It begins with a description of coinage metals and their properties, then goes on to the changes that these metals and their alloys suffer over time, the cleaning of coins, the removal of corrosion products, various other techniques for the treatment of coins, and several further sections with topics such as protective coatings, how to make worn inscriptions visible, how to make plaster casts and other reproductions, coin photography, metal analysis, and authentication methods.

If one can read German Welter's book is a treasure. I don't know whether further editions were published.