Copying inks may be made by adding a small quantity of alum to an extract of logwood. To this is added table salt or sugar and glycerine. The inks so obtained are purple when first used, and darken gradually on the paper. The copies taken from them darken still more slowly. Violet writing ink may be converted into copying ink by the addition of glycerine in the proportion of about 3 parts of the latter to 4 parts of the violet ink. If a quantity of glycerine slightly less than the foregoing be used, the ink will copy within a quarter of an hour after writing. An ink which will yield one or two copies by hand pressure may be made by mixing, say, lpt. of glycerine in 3pt. of jet-black writing ink. The following is a recipe that has been recommended. Pla,ce 2 dr. of crystallised carbonate of soda and 1 oz. of extract of logwood in a porcelain receiver with 8oz. of distilled water. Heat this until the solution reaches a deep red colour and everything is quite dissolved. Then remove it from the fire and stir in 1 oz. of glycerine, 15 gr. of neutral chromate of potash, and 2 dr. of finely pulverised gum arabic, each of the latter dissolved in a little water. This is another recipe.

Take 4gal. of soft water (preferably rain water),and add gum arabic, clean copperas, and brown sugar, using of each 1/2ib. (not more), and lib. of powdere 1 nutgalls. Allow this to stand for two weeks, shaking occasionally, then strain. This ink will not fade on exposure to the atmosphere. A simple method of making copying ink is to evaporate loz. of ordinary ink to a quarter of its bulk, and dissolve in it 20 gr. of powdered sugar. Another recipe is to boil together1/2 lb. logwood extract, 2oz. of alum, 4 dr. sulphate of copper, 4 dr. sulphate of iron, loz. of sugar, and 4 parts of water, and filter through flannel. Add a solution of 4 dr. of neutral chromate of potash in 4oz. of water, and a solution of 2oz. of chemic blue in 2oz. of glycerine. For red copying ink, dissolve 5 parts of logwood extract in 150 parts of distilled water without the aid of heat; add 'i part of chromate of potassium, and set aside for twenty-four hours, and then add a solution of 'i part oxalic acid, 4 parts oxalate of ammonium, and 8 parts of sulphate of aluminium in 40 parts of distilled water, and again set aside for twenty-four hours. Boil in a copper vessel, and add 10 parts of vinegar.

In a fortnight's time decant and bottle.