ScientificAmerican1920-10-23.jpg Scientific American 1920-09-18ThumbnailsScientific American 1920-11-27Scientific American 1920-09-18ThumbnailsScientific American 1920-11-27Scientific American 1920-09-18ThumbnailsScientific American 1920-11-27Scientific American 1920-09-18ThumbnailsScientific American 1920-11-27
Melting gold coins in the United States Assay Office.