Hyposulphite of soda, about 1 lb. to a gallon of water,
constitutes the fixing solution; its function is to dissolve all
the chloride of silver that may remain in the prints after their
previous washing and toning. [p078]
The prints should be immersed one at a time, and kept in motion so
that the solution may have an equal action. When there are a large
number of prints the dish containing the fixing solution should be
correspondingly large, so that the prints may not be massed
together but kept separate and free for the more perfect action of
the fixing solution; they should be kept in motion until the
fixing is completed, which will be in about 15 or 20 minutes. Some
printers ascertain that the action is complete by holding the
print up and examining it by transmitted light; if it looks
mottled and uneven it is not fixed, but if you can see the fibre
of the paper and all is clear, then remove the prints from the
hypo into a dish containing brine or common salt and water, one by
one as before, and keep them in motion in this brine until all are
well saturated with it; then let fresh water run into the dish,
which will gradually change the brine to clear water.
The prints are put into the brine, and this gradually changed to
clear water to prevent blisters or a separation of the albumen
from the paper in the form of blisters. The water may be allowed
to run into the dish, the prints being kept in motion, and in the
course of an hour they will be sufficiently washed; they may then
be taken out and placed between the sheets of blotting paper to
remain until next morning, when they can be overlooked, the
blemished prints thrown out, and the perfect may be mounted.
The fixing solution should not be used a second time, but should
be thrown into a large barrel with the washings, that at some
future time the silver may be recovered; when the barrel becomes
full, a small amount of saturated solution of protosulphite of
iron [p079] may be thrown in, the water stirred well, and when
the sediment has settled to the bottom the clear liquid may be
drawn off and the barrel is ready to receive the next washings of
hypo.