Information on Azo from: http://www.postcardsofhamilton.com/post_term.htm#top; Postcard depicts the Joseph Priestley Memorial Unitarian Church in Northumberland, PA. The photograph used on the card presumably dates to before 1910, since it does not show the plaque on the front of the church that commemorates the 1910 rededication as a memorial to Priestley. Caption on verso: A Z O. Refers to Azo, a type of photographic paper introduced in 1898 and used to produce the postcard.; Postcard
Collection:
Edgar Fahs Smith Image Collection (University of Pennsylvania)
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