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DYEING AND CALICO PRINTING.

a fugitive stain, and requires, therefore, the intervention of a mordant. Thefirst step is the solution of the colour. One of the best methods for woollensis to arrange a small flannel filter at one corner of the dye-beck, with its bagdipping below the surface of the liquid, but with its edges above. The re-quisite quantity of magenta crystals is weighed out, wrapped carefully up ina piece of clear flannel or close-grained calico, and allowed to dissolve in thehot water.

It is very important that no particles of undissolved magenta should beallowed to escape into the dye-bath, as they will attach themselves to thegoods and form intense red or even bronzed spots. This precaution is par-ticularly necessary in piece dyeing. As the affinity of magenta for woollentissues is very great, without care the shades produced will be uneven. It is,therefore, well to dissolve only part of the requisite amount of magenta atonce, wincing the pieces very rapidly in the weak-coloured liquid. Thepieces or yarns are then lifted out of the dye-beck, the rest of the colourdissolved, the goods re-entered, and worked till the required shade is obtained.

For silk and cotton dyeing, where the dye-beck is not at so high a tem-perature, and where, consequently, the magenta cannot be readily dissolvedin the manner above mentioned, the colour is previously dissolved and addedto the dye-bath. When the aniline colours were first introduced the magentacrystals were dissolved in hot alcohol or methylated spirit, boiled for about aquarter of an hour, very carefully filtered through flannel, and preserved tillwanted in stoppered bottles. In dyeing, the necessary amount of thissolution was added to the dye-beck. This method was open to several dis-advantages, as the cost of the alcohol, and its gradual evaporation during theprocess of dyeing, when the magenta was apt to separate out as a bronzescum, and to soil the tissues. Worst of all, the employment of a largequantity of alcohol was found to render the colours flat and dull. Great careis needed in the selection of a commercial alcohol for use along with magenta.It must be free from shellac—a common impurity. If this is present thecolour works flatter and has a bluish tone, which is not desirable. Shellacmay be easily detedted by adding a little of the suspedted spirit to an excessof water when the shellac is deposited. Pure alcohol when heated with 1 percent of pure caustic potash should turn a bright yellow. If it becomes brownit should be rejedted as contaminated with fusel and empyreumatic oils, whichhave an injurious effedt in dyeing.

Some dyers dissolve magenta in acetic acid, which takes it up very readily,but gives it a blue shade. A good method is to reduce the magenta crystalsto fine powder, rub them well up with their own weight of alcohol, and allowthe mixture to stand overnight in a closed vessel. In the morning the pastethus obtained is mixed with the smallest needful quantity of boiling water,boiled up for a few minutes and filtered into the dye pan through flannel.

Another method is to rub up the magenta in glycerine, and then boil inthe smallest quantity of water needful to dissolve it, and filter for use.Glycerine is preferable to alcohol, because it does not evaporate, prevents“ bronzing” on the surface of the tissues to be dyed, and has no “ flattening”effedt upon the colour. Indeed, were it not for its high price it would belargely added to the dye-bath in almost every case where aniline coloursare employed.