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Ferric Ammonium Citrate: Ferric Hydroxide Dissolved in Citric Acid and Ammonia
Iron and ammonium citrate is the light-sensitive salt of the blueprint (cyanotype). The British Pharmacopoeia formula (US Dispensatory, 1907): throw down ferric hydroxide from ferric sulphate with ammonia, wash it, dissolve it in warm citric acid, add ammonia, and dry the syrup in thin layers below 38 °C to garnet-red scales. Keep it from light.
The picture: ferric ammonium citrate (Wikimedia Commons).
Intermediate
2 days
Instructions
1
1
Make 10 % ammonia water
Make 10 % ammonia water
Mix 2 parts of strong ammonia (25-28 %) with 3 parts of water to get about 10 %. You need about 460 ml.
Materials for this step:
Ammonia Solution - 25-28%190 mlTools needed:
Distilled Water
Borosilicate Beaker
Rubber Gloves2
2
Throw down ferric hydroxide
Throw down ferric hydroxide
Mix 320 ml of the ammonia water with 800 ml of distilled water. Dilute 200 ml of ferric sulphate solution with 800 ml of distilled water and add it slowly, stirring briskly, until the mix smells faintly of ammonia. Leave 2 hours, stirring now and then.
Materials for this step:
Ferric Sulphate Solution200 mlTools needed:
Distilled WaterBorosilicate Beaker
Glass Stirring Rod3
3
Filter and wash
Filter and wash
Pour onto a calico filter. When drained, wash the brown ferric hydroxide with distilled water until the washings are free of sulphate.
Tools needed:
Coarse Cotton Filter ClothDistilled Water4
4
Dissolve in citric acid
Dissolve in citric acid
Dissolve 80 g of citric acid in 80 g of distilled water and warm it on a water bath. Stir in the drained hydroxide until nearly all of it has dissolved and the acid is saturated.
Materials for this step:
Citric Acid80 gTools needed:
Distilled Water
Large Pot (lower, for water bath)Borosilicate BeakerGlass Stirring Rod
Balance Scale5
5
Add ammonia and filter
Add ammonia and filter
Let it cool, add 110 ml of the ammonia water and filter through flannel, adding a little distilled water if needed.
Tools needed:
Wool FlannelDistilled Water6
6
Dry to scales
Dry to scales
Evaporate to a syrup, keeping a very slight smell of ammonia. Spread thinly on glass plates and dry below 37.8 °C (100 °F). Lift off the flakes and keep them in a dark, closed jar.
Tools needed:
Evaporating DishLarge Pot (lower, for water bath)
Glass Sheet
Thermometer
Dark Glass Jars with Airtight LidsMaterials
3- Placeholder
- 200 mlPlaceholder
- 80 gPlaceholder
Tools Required
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