The story
The company can trace its roots to the Pharmacie-Droguerie Hédouin, a pharmacy founded in 1827 in the rue Saint-Merri, Paris.
The baker Pierre Wittman (1798–1880) bought the store in 1845.
His daughter, Pauline Wittmann (1828–1910), married Étienne Poulenc (1823–78) in February 1851.
They had three sons: Gaston (1852–1948), Emile (1855–1917) and Camille (1864–1942).
Etienne Poulenc was a pharmacist and a chemist, and partnered with his father-in-law.
He became sole owner in 1858.
With his brother-in-law Léon Whittman, Etienne began to manufacture photographic products, which up to then the business had only retailed, under the "P.W." brand.
Starting in 1852 the products needed for photographic collodion were prepared or packaged in a factory in Vaugirard.
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These included silver bromide and iodide, iodine chloride and sodium thiosulfate ("hypo").
In 1859 Poulenc opened a factory in Ivry-sur-Seine that prepared salts of iron and antimony, and many products needed for manufacture and processing of the new gelatin-silver bromide plates, which had replaced collodion: ammonium ferric citrate, sodium acetate, and compounds for fixing and developing the photographs.
Étienne Poulenc became well known for manufacturing chemical products for use in photography.
Poulenc et Wittmann of 7 rue Neuve-Saint-Merri exhibited at the 1878 Universal Exposition.
The firm sold chemical, pharmaceutical, photographic and industrial products.
From Wikipedia’s article on Poulenc Frères, shared under CC BY-SA 4.0.3