[pure-silver] Re: Hubl's book and panchromatic sensitivity
- From: Jean-David Beyer <jeandavid8@xxxxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Sat, 17 Oct 2009 21:58:56 -0400
Ray Rogers wrote:
Hi Richard!
Yes. If I am not mistaken, it may even have been in connection with
collodion plates that it was discovered. I have the details on my other
computer, but anyway it was Vogel who made the discovery, and yes there
was color sensitization going on and chlorophyll was one of the
sensitizers.
Nice find. I have one or two of his books... how long is the one you
picked up?
Ray
My great grandfather (F.E.Ives) made color sensitive plates before December,
1879 as an account of it was printed in the _Philadelphia Photographer_
then. Probably between 1873 and 1877, when he worked for Cornell University.
He makes a plate by coating it with _Newton's emulsion_. These were wet
collodion bromide emulsions. As soon as the emulsion is set, he poured an
alcoholic solution of chlorophyll and flowed it back and forth for about 30
seconds, and then washed it until it was smooth. He then poured "tea
organifier" (tea one-half ounce, water ten ounces), rinse, and exposed
through a suitable yellow filter.
To prepare the chlorophyll, first extract everything soluble in water from
myrtle leaves, by treating them with a number of changes of hot water. Then
dry the leaves, and the chlorophyll may be extracted at any time by treating
about an ounce of leaves with four ounces of hot alcohol.
The solution should be a deep, pure green color, and will remain good
for a long time _if kept in the dark_. It spoils very soon if exposed to a
strong light.
Later he used chlorophyll and eosine together to make the plates panchromatic.
As far as I can tell, Vogel did not use chlorophyll.
--
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