Sir John Herschel was the scientific superstar of the 19th century. He was an inventor, chemist, astronomer, botanist and photographer who made some of the most important technical contributions to photography. Most importantly, he is credited with coining the term ‘photography’ in the english language, deriving it from the french word ‘photographie’ in 1839 after Daguerre’s process was announced to the world.
Throughout 20th century photography and in present day photographic discourse, Herschel remains an almost forgotten figure. Although some of his important contributions came to light only after Louis Daguerre‘s public announcement in 1839, they were very pivotal in shaping photographic practice.
One of his main contributions to photography came in 1819 when he discovered that sodium thiosulphate (‘hypo’) can be used as a solvent for silver halide based photography (that was being worked upon by Daguerre and Niépce in France and by Talbot in England. Fixing or stabilizing an exposed and developed image was one of the biggest impediments in making photography a complete process. Those working on the process had achieved limited but unsatisfying results with a solution of regular table salt dissolved in water. Thus the exposed and developed images were still light sensitive and could not be brought out into proper daylight and would soon fade away if done so. Herschel’s invention ensured that it was not so, and hypo continues to be used in fixing in black and white film and paper chemistry till date.
His experimenting with photochemistry also lead him to invent the cyanotype process. He invented his process much after both Daguerre and Talbot announcing his processes. Herschel’s process though is different as it is a non-silver process, unlike most processes of 19th and 20th century. Herschel’s process produces a permanent blue and white image due to the use of iron salts. There are different versions of the process that give varying visual results, such as using gold instead of iron to get a red and white image. The cyanotype process uses a mix of two chemicals (potassium ferrocyanide and ferric ammonium citrate) that when brushed on paper produces a light-sensitive organic surface to make images on. This surface not ideally suited for in camera due to the reduced sensitivity, however it was well suited for contact printing. Putting this sensitive paper in contact with a negative and then placing them it in the sun would produce a latent image. This latent image could be developed plain water to get a bright blue image. This process also lead to Herschel coining the terms “negative” and “positive” that are used in photography to this day.
Cyanotype as a process did not get much use in the 1840’s however it did become very popular with botanists as a means of keeping record of botanicals. Cyanotype saw its use become very popular in late 1890’s when it started being used in engineering applications where it started being used in what we now call “blueprints”. Later on, photographers also started to use it as a means of making cheap photographs or for making test prints and contact sheets.
Herschel died in 1871 and was buried in Westminster Abbey, years later, Charles Darwin chose to be buried next to him, citing him as an important inspiration.
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