BB Blue.—This is produced from pure rosaniline, 2000 grms.; pure aniline, 5000 grms. ; benzoic, or glacial acetic, acid, 270 grms.; treated as above. The crude product is thus purified : the boiling mass ia turned into an enamelled iron pot, and cooled by being placed iu water ; 7-8 kilo. concentrated alcohol are added, and the mixture is stirred till well incorporated; the vessel is heated in a salt-water bath till the alcohol begins to boil ; it is then allowed to cool a little, and stirred, adding 10-12 kilo. strong hydrochloric acid ; the mass becomes warm from the formation of hydrochlorate of aniline, and at the same time the pure blue separates. To obtain a product of constant colour, the filtering should always be made at the same ternpemture-45°-50° (113°-122° F.); the blue is washed with plenty of water, and dried. The product should be about 1320 grms.
This blue can alao be made from B, by treating one part of the latter with lf part atrong alcohol, and 5 parts rectified benzol, introducing the whole into an apparatus supplied with an agitator and coliobator, and boiling for one hour.
BBB, and BBBB Blues.—These aro prepared by a further purification of BB, 1 kilo. of which is boiled with agitation for two hours with 36 kilo. strong alcohol ; 2 kilo. of an alcoholic solution of soda, containing 20 per cent. alkali, arc poured in, when the soda sets the base free. The alcoholic solution is filtered, when a oertain quantity of inferior blue is left in the filter. With the alcohol solution still warm, 280 grma. concentrated hydrochloric acid are well mixed ; by leaving the whole to settle for about two houre, BBB is deposited in a crystalline form ; this is filtered, pressed, and when dry, should yield 600-690 grms. By repeating this operation on the same product, BBBB is obtained. From the mother-liquor from which BBB has been precipitated, a further quantity of an inferior blue can be libtained.
A better plan is to dissolve 1 kilo. BB in a mixture of 1 kilo. alcohol, and 2 kilo. aniline, stirring till blended, pouring the whole into 25 kilo. alcohol, and heating till the alcohol boils ; finally adding an alcoholic solution of soda, and filtering. This gives much leas insoluble matter. To the filtrate is added a little excess of hydrochloric acid, when a superior blue is thrown down ; at the end of forty-eight hour° it is filtered off, pressed, waahed several times with boiling acidu lated water, and dried. it yields about 800 grms. BBB.
Nicholson's Blue.—Triphenyl-rosaniline-sulphonio acid is obtained by dissolving triphenyl-roaani line in concentrated sulphuric acid, and adding water to the solution ; a dark blue mass ia formed which dries up into grains, having a beautiful metallic lustre. Its sodium salt is "Nicholson's "
or " Alkali" blue, a dark-grey amorphous mass, dissolving in water with a fine blue colour. By the further action of sulphuric acid, other aulphonic acids are fortned, and occur, as sodium salts, iu several soluble aniline blues. The amtuonium aalt is Nicholson's ordinary "soluble " blue.
To prepare Nicholson'a blue, " Blue de Lyons," or " Azaline," ia boiled in water containing about 4 oz. sulphuric acid to 1 gall. water ; when tLe soluble matter is nearly all takeo up, the insoluble residue is dried, and reduced to powder, and about four times its weight of sulphuric acid (sp. gr. 1'845) is added to it ; the temperature is raised to about 149° (300° F.); the mixture is stirred till aolution is complete, and is kept at this temperature till a sample is entirely dis solved in water. If the temperature be raised too high, sulphurous acid will be evolved, to the destruction of the dye. Its dilute acid solution is used for dyeing and printing in the ordinary way. By the use of an excess of lime or alkali to neutralize the acid, it is thrown down, and a colourleas solution is obtained, which, on addition of a weak (organic) aoid, develops a soluble blue.
By varying the proportion of sulphuric acid, the heating may be curtailed or prolonged : it is best to work on small quantities, so as to limit the generation of heat. The tints are improved by increasing the acid ; but when very laxge quantities are used, the colours are more fugitive ; the proportions giving the most durable colours are those required to prodwe mono- and di-phenyl rosaniline sulphonic acids, and heating to 100° (212° F.); these colours, however, are not se soluble as when the heat has been raised to 149° (300° F.). Anhydrous sulphmic acid ma,y be used instead of concentrated acid, without heating. Caro (1877, No. 3731) converts the crude magenta bases into sulpho aoids in the same way. The advantage of these dyes is that they can be used in presence of acids or acid mordants.
Diphenylamine Blue.—Girard and De Laire (1866, No. 2686) prepare a blue from diphenyla,mine and sesquichloride of carbon, by heating a mixture of 2 parts of the former and 3 of the latter, for five to six hours, iu an enamelled iron vessel, to 170°-190° (338°-371° F.). The apparatus used is the same as for making diphenylamine.