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This page describes trade processes that use dangerously toxic materials such as cyanide solutions, mercury amalgams, or strong acids. These processes require training, equipment, and precautions far beyond what the text describes.
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Home › Liquid Colors › Cochineal Coloring (Take ounce each powered)
Cochineal Coloring (Take ounce each powered)
Take 1 ounce each powered cochineal, carbonate of potash, bitartrate of potash, and alum; boil these in a glazed vessel with 7 ounces water and 1 ounce spirit of wine, until effervescence ceases (about 10 minutes). In this liquid dissolve an equal weight of refined sugar by means of sufficient heat, and set aside for use.
This coloring remains bright for any length of time, does not throw down any precipitate, and is almost unalterable by contact with either acids or alkalies, which is no small advantage. Dickson's coloring has some disadvantages in the large quantity of spirit and the delicacy of the ammonia tint. The first would have a tendency to cause a cloudy appearance mixed, remove the pot from the fire, and continue to stir until the liquid is cold. If the paint be desired thicker or thinner, the amount of starch and glue must be varied as well as the other materials, or the lustre will suffer. 2627. Black Produced by the Mixture of Colorless Liquids. One of the most interesting phenomena in the operations of chemistry occurs in the decomposition of sulphate of iron by gallic acid. Into a wine-glass, containing the infusion of galls, pour a solution of the sulphate of iron. The gallic acid, from its superior elective affinity to the iron, dotaches it from its former combination with the sulphuric acid, and in a short time these two fluids, previously colorless, become intensely black. To make this black fluid into ink, nothing but a little gum is required, to retard in bright jellies and other preparations con- the precipitation of the coloring matter. taining gelatine, and the ammonia color would 2628. Το Make Liquid Blue. Put be liable to be completely changed when into a bottle 1 ounce pure Prussian blue, in brought in contact with lemon juice, baked fine powder, and pour upon it 2 ounces conpears, and other acids met with in the many centrated hydrochloric acid. Effervescence culinary purposes for which the article is largely used.