The Cyanotype, which is also known as ferroprussiate or blueprint was invented by Sir John Herschel in 1842, when he discovered that ferric (iron) salts could be reduced to a ferrous state by light and then combined with other salts to create a blue-and-white image. Not long after, Anna Atkins, one of the few women in photography during that century, published the first book with photographs instead of illustrations, "British Algae: Cyanotype Impressions"