For soap it is customary to use a mixture of yellow and blue which together produce a green color. Take a yellow soap, melt it, and add to it the finest powder of smalt or ultramarine until the desired tint is obtained. Indigo-carmine cannot be used, as it would impart a blue color to the skin.
For many preparations smalt or ultramarine is employed, but these colors are insoluble. The only soluble blue colors are aniline blue and indigo-carmine; the latter has a beautiful and intense color, but is suitable only for pomades and not for soaps because, as stated above, it would stain the skin.
is produced by a mixture of red and blue in due proportions.
is produced by caramel, which is made by heating sugar in an iron pot until it changes into a deep black mass which is brown only in thin threads. This color dissolves easily in water (not in alcohol) and is very suitable for soaps.
is produced by finely divided vegetable or bone black. Liquids are colored with India ink which remains suspended for a long time owing to the fine division of the carbon.
In the toilet, besides combs and hair brushes, use is made of powder puffs, tooth brushes, and bath sponges. Powder puffs are made from swan skins, but should be used rather for the even division of the powder or paint than for its application. For the latter purpose a piece of soft glove or chamois leather is best.
The commercial tooth brushes are almost without exception objectionable owing to the stiffness of the bristles. A suitable tooth brush should be made of very soft, flexible bristles, lest it wear away the enamel.
Particular attention should be devoted to bath sponges. Their value is proportionate to the fineness of the pores, their softness and elasticity, and their spherical shape. Crude sponges are best cleansed by being placed in dilute hydrochloric acid which dissolves the calcareous particles adhering to them.
Free them as far as possible from sand and other foreign matters. Then wash them thoroughly with water, and press them. Next introduce them into a solution of permanganate of potassium containing one ounce of the salt in a gallon; leave them in this liquid two or three minutes; then take them out, express the liquid (which can be several times used over again), wash them with water until no more violet-tinted liquid runs from them, and then immerse them in a solution of one part of hyposulphite of sodium in twenty parts of water, to which immediately before dipping the sponges one part of hydrochloric acid has been added. When the sponge’s are white, remove them and wash them thoroughly with water.