The
astronomer Sir John Herschel published his account of the cyanotype process
in 1842. He was a friend of Fox Talbot and his researches into light-sensitive
materials had run on similar lines to Talbot's. However, as his inquiries
were motivated by purely scientific considerations rather than for the
possibility of commercial or artistic success, there was no real rivalry
between them as there had been in the case of Talbot and Daguerre. In
addition to his reputation as a scientist, Herschel's main claim to fame
was his discovery of sodium thiosulphate as an effective means of fixing
a photographic image on paper and thus preventing it from fading. This
substance, erroneously known as sodium hyposulphite or more commonly hypo,
was crucial to the development of the new science of photography and has
been an essential item in every darkroom to the present day.
Many of the early inventors had concentrated their efforts on compounds of silver to obtain an effective means of producing a photographic image. Herschel on the other hand used his wide scientific knowledge to explore other areas of research, and arrived at a method which used two simple compounds of iron to make his light sensitive material. The resulting print was prussian blue or cyan in colour, and was known as cyanotype. It was the first of the early photographic processes to be used to illustrate a book. Anna Atkinson, a mutual friend of Herschel and Talbot, had been making studies of algae and other plant forms and found it very difficult to make accurate and detailed drawings of the specimens that she had collected. The cyanotype process was used as a method of producing photograms of her collection, and the result was published as a series of part works. Her book pre-dated Talbot's book 'Pencil of Nature' by some months.