I found this interesting reference to coins in a 1950's mystery novel, the story is set in 1950 in the French Riviera. Two men, Coco and John, are watching a house. (Coco) "I've been sweating silver five-franc pieces wondering if you could make it", he whispered. "Merde alors, I would have conked the girl if she had sold you, John. What did you tell her?" (John) "Everything". From To Catch A Thief by David Dodge, published 1951. France minted silver five-franc coins for most of the 19th century, they were about the same size and weight as United States silver dollars. A smaller version was minted in the early 1960's. France silver five francs 1831-D (Lyons) France silver five francs 1873 By the 1930's inflation had forced the coins to be made from cheaper metals: France aluminum-bronze five francs 1940 France silver five francs 1964 Apparently the old five-franc coins were a fond memory to French people in the early 1950's, as silver dollars are a fond memory to Americans. David Dodge was an accountant before he became a writer, and there are many references to foreign exchange in the book. A French 10 franc coin also appears (worth US 3¢ then) If the book's title is familiar, the book was made into a movie in 1955, starring Cary Grant and Grace Kelly. More information on David Dodge: http://www.david-dodge.com
Here's another one from the California Gold Rush year of 1849: France 5 Francs 1849-A (Paris) Ceres Head Now I am "sweating silver five-franc pieces".