_Jet Black on Wool_.--Make the dye-bath with 4 lb. Victoria Black B, 1/2 lb. Fast Yellow F Y, 10 lb. Glauber's salt, and 2 lb. sulphuric acid, working at the boil for one hour. A very fine shade is thus obtained, which is fast to acids, alkalies and soaping. By omitting the Fast Yellow a blue black is obtained, while by using Acid Green instead a greener tone is given to the black. In place of the Victoria Black B the two other brands, 5 G, and G, of these blacks may be used. These give equally fast blacks of a deeper and more jet black. _Black on Wool_.--Prepare a bath with 5 lb. acetic acid, 9 deg. Tw.; enter the wool for one hour, then lift and add 5lb. Naphthol Black 3 B, and 1/4 lb. Indian Yellow. Re-enter the goods and boil for one hour, wash and dry. Many of the black dyes--Naphthol Black, Naphthylamine Blacks, (p. 092) Naphthyl Blue Black N, Acid Black B, etc.--are capable of slowly dyeing wool from neutral baths, that is, containing only Glauber's salt, or rather more quickly if a little acetic acid be present. Such dyes are very useful for dyeing heavily milled or felted fabrics, such as hat bodies for instance, as then the dye possesses greater penetrative properties and passes more into the substance of the fabric, which is, therefore, better dyed through. Also they are suitable for dyeing half-wool fabrics as will be seen on referring to the chapter dealing with the dyeing of union or cotton-wool fabrics. It is quite possible to dye a black on wool by using a combination of acid and azo dye-stuffs, and below is given a recipe illustrating this method; it is one, however, rarely adopted. _Blue-Black on Wool_.--Prepare the dye-bath with 10 lb. Glauber's salt, 2 lb. Patent Blue, 6 oz. Brilliant Orange, 4 oz. Amaranth, 4 oz. Acid Violet N, 4 lb. sulphuric acid. Enter the goods at about 150 deg. F., raise to the boil and work to shade; lift, wash and dry. It may be of interest to note that by using a mixture of Azo Rubine and Acid green good blacks can be got. There is a range of Acid and Azo dyes which are capable of dyeing from the usual acid baths on to wool, and yet can be developed and fixed on the fibre to good, full blacks. Types of such dyes are Anthracene Chrome Black F F, Diamond Black F, Chrome Patent Black D G and D G G, Fast Chrome Black, etc. Generally the blacks dyed on wool with these dyes are very fine, have a full, bloomy appearance, and are very fast. They are much used in dyeing hat bodies and fine cloths which have to be very fast to the weather. The method of application will be gleaned from the recipes given below. _Black_.--Prepare a dye-bath with 5 lb. Chromotrop S, 1/4 lb. Azo (p. 093) Yellow, 50 lb. Glauber's salt. Work for one and a half hours at the boil, then add 4 lb. sulphuric acid. Work at the boil for another half hour, then lift. Add to the same dye-bath 3 lb. bichromate of potash. Re-enter the goods and work at the boil for half an hour, then lift, rinse and dry.