Development in the Dark Room. 35 
of potash should be as clear as the purest spring water, while the 
iron solution should be of a beautiful transparent pea-green color; 
and when mixed together, they will immediately change into a 
rich color, varying from a topaz sherry to a ruby red, according 
to the proportions of the ingredients used. These two solutions 
when properly stoppered, will keep indefinitely ; and when mixed 
in the proportion of one part of iron to six parts of oxalate, will 
last for months if the air is all excluded. The action of air upon 
this and all other developers is very injurious, causing oxidation, 
and how to prevent this oxidation has been the subject of much 
discussion and many experiments. 
I have very little faith personally in the success of any attempt 
to preserve the developer by the addition of chemicals, although 
it must be admitted that glycerine and alcohol appear to approx- 
imate in some degree to the desired result; and none of the 
mechanical contrivances invented for the purpose of getting the 
developer out of the bottle, without at the same time admitting the 
air, have proved successful. The simplest deviceI have yet heard 
of for excluding air from the bottle in which the developer is kept, 
when one has not sufficient developer to completely fill the bottle, 
is to drop into it a sufficient number of pebbles, or glass marbles 
such as all school-boys have, to expel the air. Then when prop- 
erly corked, the oxidation is reduced to a minimum. This plan, 
of course, necessitates the use of wide-mouth bottles. 
This ferrous oxalate developer I consider one of the most use- 
ful an amateur cdn have. There is no long formula to remember 
—no weighing out of the ingredients into grains and fractions of 
grains—it 1s cheap, reliable, easily controlled, and the printing 
qualities of the resulting negative, if the plate has been properly 
timed, can not be excelled. The greatest objection I have found 
to its use is the fact that it stains almost indelibly the hands, and 
anything in the nature of cloth with which it comes in contact. 
With this developer, as well as with all others, I have come to 
the conclusion, late in the day, that the proportions of acid and 
alkali should be uniform, no matter whether the plate is under- 
timed, correctly timed, or over-timed. The developer may be 
weakened by the use of water, if you think it is desirable, but 
my advice to beginners is to disregard entirely the suggestions 
c=) 
they will be sure to meet with, that a little more of No. 1 (acid) 
will give increased density, and that a little more of No. 2 (or 
