The following formula for stock jelly for carbon printing can be highly recommended. Nelson's opaque gelatine 4oz., Coignet's gold label gelatine 1 oz., loaf sugar 1 1/2oz., water 1 pt. Heinriclr s emulsion gelatine may be substituted for Coignet's if the latter cannot be procured. These are harder than Nelson"s opaque. Gelatine that has been artificially hardened with alum must not be vised. To the above is added for sensitising as required potassinm bichromate solution in the proportion of 12 drops per ounce. This solution is made by dissolving 1/2oz. of potassinm bichromate in 5 oz. of water, and adding about 1/2 dr. of liquor ammonia. Allow the gelatine to soak for a time, and dissolve by heat in part of the water. Dissolve the sugar in the remainder, and add gently whilst stirring. Various colours may be used, but Chinese ink is a favourite with workers in a small way. Allow this to soak till it is in a thin paste, then add to the jelly until a piece of paper floated upon it and drained appears quite opaque when held against an ordinary gas jet. Stir thoroughly when adding the pigment, and put in only a little at a time.

Any pigment may be used which is in a fine state of division.