Enquire within upon everything

2683. General Observations. The various shades produced by colouring matters may be classed in one or other of the following groups: 1. Blues } 2. Reds } Simple. 3. Yellows } 4. Violets } 5. Orange colours } Binary. 6. Greens } 7. Compound colours } 8. Black } Ternary. Some colours adhere at once to the stuff, and are called substantial colours; while others require that the material to be dyed should undergo some previous preparation in order to render it permanent. The substances used to fix the colouring matters are called mordants, which should possess four qualifications: i. They should possess an equal affinity for the fibre of the material and the colouring matter. ii. They should be incapable of injuring or destroying either by prolonged action, iii. They should form, with the colour, a compound capable of resisting the action of air and water. iv. They should be capable of readily conforming to the various operations of the dyer. 2684. The Mordants. For the reasons just given, the acetate or tartrate of iron is preferable to the sulphate; and the acetate or tartrate of alumina to alum. For reds, yellows, green, and pinks, aluminous mordants are to be used. For blacks, browns, puces, and violets, the acetate or tartrate of iron must be employed. For scarlets, use a tin mordant, made by dissolving in strong nitric acid one-eighth of its weight of sal-ammoniac, then adding by degrees one-eighth of its weight of tin, and diluting the solution with one-fourth of its weight of water.