A. Gum arabic 15 parts
Water 100 parts
B. Ammonia ferric 45 parts
citrate
Water 100 parts
C. Ferric chloride 45 parts
Water 100 parts
For sensitizing mix _in order_:
Solution A 100 parts
Solution B 40 parts
Solution C 20 parts
The mixture very much thickens at first, but becomes sufficiently fluid
for use in a few hours. It keeps well for two or three days. Leaving out
B and replacing it by rain water, this makes also a good solution for the
cyanotype.