Physautotype
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The physautotype (from French, physautotype) was a photographic process, invented in the course of his investigation of heliography, by Joseph Nicéphore Niépce and Louis Jacques Mandé Daguerre[2] in 1832, in which images were produced by the use of lavender oil residue dissolved in alcohol as the photographic agent.[3][4] The solution was coated onto a silver or glass plate and allowed to dry, after which it had a powdery white appearance.[citation needed] The plate was then exposed in a camera obscura for about 8 hours and developed with petroleum-based spirit vapors,[3] which caused the least strongly exposed areas to become proportionally more transparent, creating a photographic image that was positive when viewed against a darker background.