2554. Aniline Blue

2554.    Aniline Blue. Aniline blue results from various processes. The one most commonly used at present is that of Girard and De Laire, made by heating fuchsine with fluid aniline. The original process produced a blue with a reddish tinge; but by the addition of some organic substances, acetic acid, and me-thylic alcohol, pure blue is obtained. It is distinguished from all other blues by not appearing green in candle light. The various shades of purple to blue and violet are made from fuchsine by Hofmann's method (see No. 2608 (To Dye with Hoffman's Purple)); heating 1 part fuchsine and 2 iodide of ethyl with 2 parts alcohol in a closed vessel at 212° for variable lengths of time; the blue resulting from longest exposure.

2555. Aniline Green

2555.    Aniline Green. Aniline green is produced from a solution of sulphate of rosaniline in dilute sulphuric acid and some aldehyde, which is heated till its color has changed to dark green. Addition of a solution of hyposulphite of soda separates the color.

2556. Aniline Green

2556.     Aniline Green. Several of the aniline greens occurring in the market are apt to undergo spontaneous destruction, sometimes in less than a day. The following is a formula which any one may make : 4 parts of pure fuchsine or rosaniline are dissolved in 6 parts water and 16 parts aldehyde (see next receipt), and are heated at 212° Fahr., until a drop of the mixture imparts to water acidulated slightly with sulphuric acid a clear blue color, when it is ready to be poured into a boiling solution of hyposulphite of soda, which is being stirred. A fine green precipitate forms, and a grayish one, which latter must be kept separate. The green is mordanted principally with acetate of alumina.

2557. To Prepare Aldehyde

2557.    To Prepare Aldehyde. Aldehyde is made by filling a tubulated glass retort, altogether to one-third full, with 32 parts absolute alcohol, 30 parts bichromate of po-tassa, and, without previous cooling, a mixture of 35 parts oil of vitriol, and 30 of water, in small portions, through a safety-tube in the tubus. After one-half of the latter has been introduced, the mixture commences to boil and al-dehyde begins to distill over, the remainder of the said mixture being added through the tubulus as required. No further purification is needed.

2558. To Make Aniline Colors Soluble in Water

2558.    To Make Aniline Colors Soluble in Water. The aniline colors insoluble in water may, according to Dr. Zinsman, be rendered soluble in the following way: - A solution of gelatine in acetic acid of about the consistence of syrup is first made, and the aniline color in fine powder is gradually added, stirring all the time so as to obtain a homogeneous paste. The mixture is then to be heated over a water-bath to the temperature of boiling water, and kept at that heat for some time. Colors in this state, if a very clear gelatine is employed, will be applicable to many decorative purposes. Bookbinders, paper-stainers, and printers will find them useful. They may also, it is said, be used to color confectionery and soaps. Before they are used for confectionery, however, it will be well to make sure that no arsenic is present.