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Show Overcome! lilcg.bility, I Acting on iiMiucsis 10 decipher II- legibb doeuiiients and papeis, par-llciilarly par-llciilarly those tln.t have passed through fire without being burned to ' ushes, the bureau of siandards has ! worked out n method that is very i 'fTeitlve and comparatively simple. It j Is based on the principle that a pho-' pho-' tographie plain or film, besides being 1 sensitive to I'ght, Is also sensitive to ! certain gases or vapors. The specimen ! under Invest'gatlon is placed betvvee" two photographic plates mid kept in Intimate contact villi the sensitized mating In the dark, for a period oi two weeks in the case of fas! pboes On development In the usual manner. I a perfect copy of the writing nnd I riming Is obtained. Popular Mechanics Me-chanics Magazine. |