Camera Work: A Photographic Quarterly (1908 (Heft 22))

nuances can be produced on a square millimetre (about one twenty-fifth
of an inch) of a plate. So it would seem that the most delicate and
minute detail can be perfectly rendered. I find myself frequently indulg-
ing in the amusement of watching painter friends’ jaws act queer when I
tell them all this , and when one talks of orange, green and violet, as
the primary colors, they do a great deal of swallowing and finallyget
panic-stricken.
The surface of starch-grains is subsequently protected and isolated with
a celluloid varnish and it is then coated with an extremely thin, fine grained
panchromatic collodion emulsion, which is very rich in silver. The emulsion
is only nearly panchromatic, however, for up to the present a perfectly pan-
chromatic emulsion is impossible—and it is along these lines that one will
expect the great improvements. The orange colored screen, which is used
on the lens in making the exposure, cuts out completely the ultra-violet rays
and further acts as a compensator for inequalities in the color sensitive
emulsion. It lengthens the exposure about three times.
The extreme thinness of the emulsion calls for careful handling of the
plate, but except during the memorable frilling period, I have not used any
precautions that one does not generally give to an ordinary plate. The one
thing to avoid is to touch the surface of the film before development. The
merest touch means a black fingermark and probably it will come right
across the face in a good portrait. Instead of the black paper supplied with
the plates to protect them from abrasion in the holders, several French
camera makers have made very useful special plate holders that have an air
space behind the sensitive surface.
Any one that enjoys working in the dark with a nerve-racking alarm
clock certainly has the option to do so, but I like all the light I can get in
the dark room. The Autochrome emulsion is slower than some well known
orthochromatic plates, which I have developed with a red light, so why not
the Autochromes ? I first worked with a commercial violet and yellow cellu-
loid safelight, which gives a deep ruby light, safe for all reasonable use.
Later I acquired one of Wratten & Wainwright’s green lights, which gives not
only more but also a safer light. The loading and placing of the plate in
the developer is done with my back to the light; at the end of thirty seconds
the tray is brought close to the light for an instant, to see how the plate
looks. Then the necessary changing, if any, in the developer is done with
my back to the light, and the plate examined every thirty seconds or so by
transmitted light—quite close to the light. Giving an unexposed plate
twice this amount of exposure during development did not show a trace of
fog with the lights mentioned above. A safe light can be made by fixing out
two unexposed gelatine dry plates, thoroughly washing them, then drying.
Dye one by immersing it in a strong solution of methyl violet, rinse and
dry. Do the same with the other in a solution of tartrazine ; subsequently
bind the two together. If one is content with the Lumière time develop-
ment formula, the dark room can be dispensed with entirely. A number of
special daylight developing machines for this purpose have been put on the

17