HF The History of Photography 600pág

The evolution of dry plates 3 3 3
ENGLANIJS
PHOTO GRAPHY-PAS
PH OTO GRAPHY- PRESEN
Fig 50 Advertisement of]. Desire England's dry plates, 1884
the sensitivity to red, and the following year MAJOR J. WATERHOUSE found the
sensitizing effect of (red) eosine in the yellow-green region of the spectrum. Two
Frenchmen, JOHN CLAYTON and P. A. ATTOUT (alias Tailfer), were the first to apply
eosine successfully to gelatine emulsion in 1882, and their eosine plates (which were
on the market in the following year) were the first gelatine isochromatic plates. The
name isochromatic (from the Greek foo, equal) was suggested by Paul Best, the
French statesman and professor at the Sorbonne, and adopted by the inventors of the
eosme process.
Vogel had meanwhile experimented with a newly discovered dye, quinoline red,
and found it to be an excellent sensitizer for the green part of the spectrum in the
collodion emulsion, which together with the use of quinoline blue made sensitizing
possible for green, yellow, and orange. Vogel's dye mixture 'Azaline', to be added
to collodion bromide emulsion, was put on the market by Johann Baptist Obernetter
of Munich in 1884, the formula remaining secret.
In the same year DR J. M. EDER perfected orthochromatism with his erythrosine dye
which rendered green and yellow more correctly than any other dye, and gelatine
dry plates of his kind were first manufactured in Vienna in 1884. Waterhouse discovered
the extreme sensitiveness to red and infra-red imparted by an ammoniacal
solution of alizarine blue, c. 1889/90.
Thus Vogel and others transformed the hitherto colour-blind emulsion into
one which was more accurately sensitive to most colours-i.e. the so-called iso- or
orthochromatic plates.39 These were, however, still comparatively insensitive to red
and over-sensitive to blue. The latter fault could only be corrected by the use of
yellow filters. Vogel's successor at the Technische Hochschule, Berlin, PROFESSOR
ADOLF MIETHE, and his assistant DR ARTHUR TRAUBE, succeeded in 1903 in extending
the sensitivity to yellow and orange, by the addition of ethyl red. This was an important
step towards the production of panchromatic emulsion (Greek 7t\I= all) -
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