CHARRED DOCUMENTS

Evening Post, Volume CIII, Issue 129, 3 June 1922, Page 10

CHARRED DOCUMENTS

HOW TO BEAD THEM,

"Making Charred Archives Legible" is the welcome heading of the account of a discovery recently reported from Washington* At a recent fire in an American post office some records contained in what was supposed to be an air-tight safe were charred beyond recognition. The .postmaster thereupon sent the relios'to the Bureau of Standards— a section of .the United States Department of Commerce which is concerned with scientific investigations. Chemical means of restoration were resorted to without success, and then photographic methods were tried. A chaired sheet of paper'was laid between two photographic iplates with the emulsion sidae of the plates next to the carbonised record. They were allowed to remain in contact for a fortnight: Then the plates were developed in the ordinary way. The resultAvas a perfectly decipherable image of the valuable records on the sheet. The contact of the'charred paper had affected the photographic plate, but wherever the ink had been'the photographic chemicals of the plate were unchanged, so-that the vu-iting could be read. It is recalled that when photographic plates were first packed for sale the manufacturers used to place printed instructions inside the boxes next to the plates. ■ They soon had to abandon this .practice, however, as they found that, after the package had stood for a long ■time, the .paper formed an image on the .plates, and spoiled them. It is believed that this phenomenon, is similar to the one that has now been utilised by the Bureau of Standards. .