may be developed in the same manner until detail may be seen in the
face, if it is a portrait; then remove it and instantly flow with a
solution of bromide of ammonium to stop developing action, then
wash, fix and dry as before.
For portraits on porcelain or opal, to be viewed as positives by
reflected light, develop until the fine half-tones in the face are
visible. When they are for transparencies, [p217] either for
window or lamp shades, develop until the detail in the high lights
of portrait or landscape are well out. This may necessitate a longer
exposure by lamp-light.
Transparencies developed by other methods receive a stain or color,
which, in many cases, is not unpleasing; for instance, the following
formula will give a very beautiful yellowish color:
Saturated solution yellow prussiate of potash, 4 ounces.
Pyro 2 grains.
Ammonia (conc.) 2 drops.
This will cover and develop one 8×10 plate, giving it an agreeable
color similar to that produced by development by sal soda and pyro,
but much more agreeable.
A very fine blue color is imparted to the plate when developed by
the following formula:
Saturated solution sal soda 5 minims.
Saturated solution potash 5 "
Saturated solution ferrocyanide of
potash 5 "
Bromide ammonium 1 grain.
Pyro 2 grains.
Water 4 ounces.
From the fact that these different developments impart different
colors to the negatives, it might be inferred that the gelatine film
is susceptible of receiving color from a stain or dye; if such is
the case, transparencies may be made in every color of the chromatic
or solar spectrum. I have seen one of a beautiful rose color, and
was informed that the color was received in development. [p218]
This was possibly so, but it is very easily ascertained if the film
of the developed plate is capable of receiving a dye of any pleasing
color suitable to the subject.