Reissue of a book by the same title published six years previously without English translation. Starts with pages on the author's background and long familiarity with the field. The bulk of the study concerns her treatment of a large collection of 100-year old commercially produced silver gelatine glass plates, found in a bad state of deterioration. They were first given a superficial cleaning, then classified according to kinds of damage. The next steps were: cleaning of the slightly damaged negatives; separation of plates stuck to each other on their emulsion sides; individual treatment of old emulsion on each plate; repair of cracked emulsion; removing of fog, a silver white layer around the edges, and other stains (all materials and techniques used are detailed); retouching the glass negatives with a commercial preparation or its formulated equivalent; and finally making a copy negative of the restored plate for documentation purposes. The next chapter illustrates with pictures the before, during, and after procedures. Other restoration measures which are discussed apply to broken plates; to film that needs softening; and to the treatment of fading. The practical work of documenting, filing and storing old photographs is the subject of several pages. A new chapter is added to this edition: it deals with how to save nitrate-based film. -- AATA