HF The History of Photography 600pág

The ca lo type and other paper processes in Great Britain 169
Cyanotype, Catalisotype [sic], and Anthotype. All of these 'types', except Cyanotype,
were poor and unreliable and failed to find practical application. A brief mention of
them will therefore suffice.
Amphitype. Announced by SIR JOHN HERSCHEL at the British Association meeting
at y ork in I 844, this process takes its name from the Greek ocµq:>w, both, because either
negative or positive pictures could be produced, according to manipulation. The
exposure time varied from half an hour to five or six hours. The name amphitype,
which had been suggested to Herschel by Talbot, was also given by Talbot to a
process of his own in I 851, with which Herschel's is not to be confused.
Anthotype. Derives its name from the Greek ocv6oc;, flower, because the juices of
various flowers, either alone or mixed with a little alcohol, were spread upon paper,
instead of mineral salts. Devised by Sir John Herschel and communicated by him to
the Royal Society in June 1842, the method was of purely theoretical interest, for it
took four to five weeks to print a positive from a negative-and even then the result
was not permanent.
Catalysotype. Invented by DR THOMAS WOODS of Parsonstown, Ireland, and communicated
to the British Association meeting at York in I 844. The paper was prepared
with a weak solution of iodide of iron and tincture of iodine. When removed
from the camera no picture was visible, but ifleft in the dark it gradually developed
itself, and it was from this catalytic action that the process took its name. The exposures
were considerably shorter than those necessary for the talbotype, but the
uncertainty of the degree of development was much greater.
Chromatype. This name covers several variants involving the use of any of the salts
of chromium. ROBERT HUNT, who coined the name, announced his process to the
British Association meeting at Cork in I 843. The paper was prepared with a solution
of copper sulphate and potassium bichromate. It produced direct positive photogenic
drawings, but was not sensitive enough for use in the camera.
Chrysotype takes its name from the Greek xpuo-6c;, gold, because the image was
developed with a gold solution. The process was communicated by Sir John Herschel
to the Royal Society in June 1842. Paper was washed over with a solution of ammoniocitrate
of iron, and after exposure in the camera was developed with chloride
of gold solution. The sensitivity was, in the inventor's own opinion, decidedly
inferior to the calotype.
Energiatype, later called Ferrotype because protosulphate of iron (ferrous sulphate)
was used as developer. Invented and communicated by Robert Hunt to The
Athenaeum on 1 June 1844, it is not to be confused with the later kind of ferrotype or
tintype. Paper was coated with a solution of succinic acid and gum arabic. When dry,
it was washed over with a solution of nitrate of silver and could be kept until
required. An exposure in the camera of 2 to 8 minutes in sunshine was given. The
result was a negative which was developed with protosulphate of iron and gum arabic.
Fluorotype derives its name from the sodium fluoride used in preparing the
paper. The introduction of this salt is due to Robert Hunt, who published the process
in Researches on Light, I 844. The exposure was only half a minute and the picture was
developed with protosulphate of iron.
Blueprints. Of all these paper processes only the cyanotype found practical application.
It is another of Sir John Herschel's inventions, described in his memoir to the
Royal Society, June 1842, and derives its name from cyanogen, which in combination
with iron plays an essential part in the sensitive coating. Too slow for anything but
copying objects by superposition, it is nevertheless the simplest, cheapest, and after Pl 75
platinotype the most permanent photographic printing process : after the paper has