text: Herschel made numerous important contributions to photography. He made improvements in photographic processes, particularly in inventing the cyanotype process, which became known as blueprints, and variations, such as the chrysotype. In 1839, he made a photograph on glass, which still exists, and experimented with some colour reproduction, noting that rays of different parts of the spectrum tended to impart their own colour to a photographic paper. Herschel made experiments using photosensitive emulsions of vegetable juices, called phytotypes, also known as anthotypes, and published his discoveries in the Philosophical Transactions of the Royal Society of London in 1842.  He collaborated in the early 1840s with Henry Collen, portrait painter to Queen Victoria.  Herschel originally discovered the platinum process on the basis of the light sensitivity of platinum salts, later developed by William Willis.
  Herschel coined the term photography in 1839. Herschel was also the first to apply the terms negative and positive to photography.
  Herschel discovered sodium thiosulfate to be a solvent of silver halides in 1819, and informed Talbot and Daguerre of his discovery that this "hyposulphite of soda" ("hypo") could be used as a photographic fixer, to "fix" pictures and make them permanent, after experimentally applying it thus in early 1839.
  Herschel's ground-breaking research on the subject was read at the Royal Society in London in March 1839 and January 1840.