Department.

PAPERS FOR BEGINNERS, No. 11.

INTENSIFICATION OR REDEVELOPMENT.

A negative which has been overexposed and developed in a normal
developer, while perfect in detail, will be thin and without contrast.
This is because it is underdeveloped, the chemicals acting too quickly
to allow it to gain density. A satisfactory print cannot be made from
such a negative, as the film, being so transparent, allows the light to
reach all parts of the paper almost at once, and the print when toned is
a dull slaty gray.

An overexposed and underdeveloped plate may be redeveloped, and this
process is usually called strengthening or intensifying. Solutions come
ready prepared for use, but the amateur who wishes can prepare his own.

The bichloride-of-mercury formula is one of the most satisfactory for
the young amateur. This is in three solutions, made up and kept in
separate bottles, labelled respectively No. 1, No. 2, No. 3. No. 1 is
composed of bichloride of mercury, 120 grains; chloride of ammonium, 120
grains; distilled water, 10 ounces. No. 2 is composed of chloride of
ammonium, 120 grains; water, 10 ounces. No. 3 is sulphite of sodium
crystals, 1 ounce; water, 9 ounces.

Wash the plate for a few minutes, and then place it for ten minutes in a
five-per-cent. solution of alum, and wash for half an hour. Place the
negative in a glass tray, and flow enough of the solution marked No. 1
to cover it. The negative will turn white, and as soon as it is white,
or nearly so, turn off the solution, and flow with No. 2 for one minute.
Rinse the plate again, and cover with the solution marked No. 3, and let
it remain till the negative has changed to a dark brown or black. Wash
for an hour and dry. No. 3 can be returned to the bottle, but the others
had better be thrown away after using once.

Another method is to bleach or whiten the plate with a solution of
bichloride of mercury, and then treat the plate with a hydrochinon
developer. Dissolve a quarter-ounce of bichloride of mercury in 12
ounces of water. Soak the plate for a few minutes in clear water, till
the film is thoroughly wet. Place it face up in a glass tray, and turn
the mercuric solution over it, till the image first disappears and again
becomes visible. Take the plate from the tray and wash away every trace
of the mercury. Place it in a developing tray, and cover the plate with
a fresh solution of hydrochinon developer. (Any formula will answer.) In
a few minute