The Indulines are very useful colouring matters for dyeing navy or dark blues on wool. They have the defect of being liable to give uneven shades. This may be remedied by omitting the acid when first making up the bath, entering the wool, working for half an hour to thoroughly impregnate the material with the dye-liquor, then adding the acid, and continuing the working for another half-hour. Or the wool may be treated to a weak chlorine bath before it is dyed, by first passing it through a weak hydrochloric acid bath and then through a bath of bleaching powder. By using acetic acid in place of sulphuric acid more even shades are obtained. _Blue_.--Prepare a dye-bath with 1 lb. Acid Blue 1 V, 9 oz. Acid Violet 1 V, 10 lb. Glauber's salt and 2 lb. sulphuric acid, working at the boil for one hour. _Blue Black_.--For this the dye-bath is made with 8 lb. Acid Blue 1 V, 10 lb. Glauber's salt, and 2 lb. sulphuric acid, working at the boil for one hour. _Deep Navy Blue_.--A very good shade is dyed with 5 lb. Acid Blue 1 V, 3 lb. Acid violet 1 V, 10 lb. Glauber's salt, and 2 lb. sulphuric acid, working at the boil for one hour. _Deep Navy_.--Prepare a dye-bath with 1 lb. Fast acid Magenta B, 3 lb. Wool Blue B X, 4-3/4 oz. Orange I I, 5 lb. sulphuric acid, and 10 lb. Glauber's salt, working at the boil for one hour. The Patent Blues work exceedingly well on wool, giving good bright shades of a fair degree of fastness. The following recipes will (p. 154) give some idea of the nature of the shades which may be obtained from them, while later on their use in combination with other dyes for the production of compound shades will be shown. _Bright Blue_.--Prepare a dye-bath with 2 lb. Patent Blue N, or Patent Blue superior, 10 lb. Glauber's salt, and 2 lb. sulphuric acid, working at the boil for one hour. _Bright Greenish Blue_.--Use 2 lb. Patent Blue V, 10 lb. Glauber's salt, and 2 lb. sulphuric acid. _Royal Blue_.--Use 2 lb. Patent Blue B, or 2 lb. Patent Blue J (No. 3), 10 lb. Glauber's salt, and 2 lb. sulphuric acid. Patent Blue J (No. 3) gives slightly more violet shades than Patent Blue N, but there is not much difference between them. _Saxony Blue_.--Use 2 lb. Patent Blue J (No. 00), 2 lb. sulphuric acid, and 10 lb. Glauber's salt. Patent Blue J (No. 00) dyes shades very closely resembling those dyed with indigo extract, and where the latter is used in the dyeing of compound shades the former might be substituted. _Brilliant Royal Blue_.--Prepare a bath with 1-1/2 lb. New Victoria Blue B, and 10 lb. Glauber's salt. Enter at about 100 deg. F., then raise to the boil and work for one hour. This gives a very brilliant shade of blue of a violet tone. _Sky Blue_.--Prepare a dye-bath with 1-1/2 oz. New Victoria Blue B and 2 lb. Glauber's salt, working in the manner described in the last recipe.