A. Ferric Ammonium Citrate (green) . . . . 1 oz. Water........ . 4 ,,

B. Potassium Ferricyanide (Red Prussiate) . . . 160 gr. Water......... 4 oz.

Or, if the brown citrate is used, substitute :

A. Ferric Ammonium Citrate (brown) .... 300 gr. Water.......... 4 oz.

B. Potassuim Ferricyanide...... 1/2 oz.

Water......... 4 oz.

Mix equal parts of A and B just before use; float the paper for three minutes, or apply with a brush or sponge. Print till the shadows show a bronze colour, and develop by soaking in three or four changes of water. To intensify immerse for five minutes in a solution of:

Ferric Chloride........ 1 dr.

Water . .......20 oz.

Brighter colour and better detail may be got by the following sensitiser :

A. Ferric Ammonium Citrate...... 1 oz.

Gum Arabic . . . . . . . . 80 gr.

Water .... 4 oz.

B. Potassium Ferricyanide...... 180 gr.

Water......... 4 oz.

A few minims of bichromate of potassium are sometimes added, if the paper has to be kept before use.

Toning Blue Prints

Bleach in 5 per cent. solution of ammonia or carbonate of potash until image has nearly faded, and then transfer to a 5 per cent. solution of tannic acid, which will give a colour varying from brown to black.

The blue image may also be converted into a silver image with 2 per cent. solution of nitrate of silver, and then be developed with any ordinary plate developer in dilute form.

Pellet's Process for copying line drawings. (Blue lines on a white ground.) -

Gum Arabic........ 360 gr.

Sodium Chloride....... 45 „

Tartaric Acid........ 60 „

Ferric Chloride........ 120 ,,

Water......... 3 1/2 oz.

Or:

Gum Arabic (20 per cent solution). . . .20 parts Ammonio Citrate of Iron (50 per cent. solution) . 8 ,, Ferric Chloride (50 per cent. solution) . . 5 ,,

Mix a few hours before required, and use when clear. Coat evenly on well-sized paper and dry in the dark. The yellow image is developed in a saturated solution of potassium ferrocyanide (yellow prussiate of potash), washed and fixed in hydrochloric acid 1 in 20.

Black Lines On White Ground

Gum Arabic........ 180 gr.

Ferric Chloride........ 180 „

Ferric Sulphate........ 60 „

Tartaric Acid........ 30 „

Water......... 3 oz.

Dissolve the gum in the water, and then add the other ingredients (ferric chloride last). The image will appear of greenish-yellow tint and must be developed in:

Gallic Acid.........1 dr.

Methylated Spirit.......2 oz.

Water.........6 „

Afterwards wash in three changes of water.

Kallitype

Coat any pure drawing paper with a solution of:

Sodium Ferric Oxalate......180 gr.

Water......... 2 oz.

Print till shadows are visible and then develop in:

Silver Nitrate...... . 10 gr.

Citric Acid solution...... 5 min.

Water......... 1 oz.

Another sensitising formula is:

Sodium Citrate of Iron......180 gr.

Potassium Oxalate.......60 „

Water.........2 oz.

Develop in:

Silver Nitrate........10 gr.

Potassium Oxalate .......80 ,,

Water.........1 oz.

Render alkaline with ammonia sufficient to redissolve precipitate. This will give black tones. For brown tones substitute borax 60 grains for the potassium oxalate of the developer.

Indian Ink Process

Float Rive's or similar drawing paper on:

Ferric Chloride........30 gr.

Citric Acid......... 30 „

Water.......... 2 oz.

Print under a negative till the picture becomes visible and then develop in a solution of gelatine containing Indian ink, or any other water colour. The coloured gelatine should adhere only to these parts where the light has acted.

Primuline

This dye has the property of becoming sensitive when nitrated by nitrous acid, and the process founded upon it, also called Diazotype, was discovered by Messrs. Green, Cross and Bevan in 1890. Paper, or any textile fabrics which are free from starch are dyed in a solution made by boiling 150 grains of primuline in 10 ounces of water, a glass flask being employed for this preliminary process.

The fabrics are kept for about ten minutes in motion immersed in the hot dye, and washed in cold water and dried.

Sensitising is done in the dark room with the following bath:

Sodium Nitrate........50 gr.

Hydrochloric Acid.......2 dr.

Water.........20 oz.

Until a uniform reddish brown colour appears, when the fabrics are rinsed in cold water, dried without application of heat and exposed under a negative, until the image is visible.

After a preliminary rinse and wring out, develop in one of the following solutions, according to colour required:

Brown

Pyro.......... 60 gr.

Water......... 10 oz.

Black

Eikonogen......... 60 gr.

Water......... 10 oz.

Purple

Naphthalamine . . . . . . . . 60 gr.

Hydrochloric Acid.......1 dr.

Water.......... 10 oz.

Red

B Naphthol........ 50 gr.

Caustic Soda........ 60 „

Water......... 10 oz.