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DYEING AND CALICO PRINTING.

That the peculiar adtion of the modified fatty substance is not simply confinedto the red, but is equally strong for purples, is proved by the fadt that theMessrs. Weber, at Mulhouse, used to manufadture a cloth, previously oiled andnext mordanted, for purples, which was so fast that it could be plunged intorather concentrated hydrochloric acid without affedting the shade in the least.According to M. Persoz the most beautiful Turkey-red cloth exhibits, on beingtorn up, a nearly white sedtion,—that is to say, the dye is rather superficial.His opinion is that the physical properties of the oil play some part in theprocess, inasmuch as it serves to envelope the particles of the lake, and toprevent the destrudtive adticn of externally applied agents. Resuming, in afew words, what may be considered experimentally proved concerning theadtion of the emulsified oil, it adls chemico-physically partly as a mordant, inas real a sense as alum; partly as a varnish, protedting as well as brighteningthe colour, the latter property being due to the peculiar transparency given'tothe cloth by the immersion in the emulsified oil.

We now return to the pradtical operations, and state first that this treatmentof the cloth in the emulsified oil-bath, drying, and exposure to air, has to berepeated several times : a small piece may be taken for trying whether theoiling is sufficiently effedted, by first working it about in a solution of carbonateof soda, and next immersing it in a bath containing a sumach infusion. If,on being removed therefrom and rinsed in cold water, the swatch assumes,when immersed in a solution of acetate of alumina, a deep yellowish tinge(isabella colour), the oiling is quite what it should be. After the oilingoperation follows the removal of excess of grease, by means of a solution ofcarbonate of soda in water, whereby the unmodified oil is removed, as well asany excess of the modified portion which adheres only loosely to the fibre.The liquid remaining from this operation is usefully employed instead ofthe first oiling, and is therefore preserved and technically known by the nameof old white bath. The operation which follows is that of applying thealuminous mordant, sometimes preceded by a bath containing an infusion ofnut-galls and sumach; sometimes, again, the aluminous mordant and theastringent materials are mixed; but in all cases the mordanted cloth is dried,and after that passed through a tepid mixture of finely-ground chalk andwater, in order thereby to aid the precipitation and fixation of the alumina.After rinsing and drying the cloth is ready for the dye-beck, wherein eithermadder or fleur de garance is used. In the former case chalk and bullock’sblood, sumach and glue, are often added ; but, the mineral matter excepted,there seems to be little use for these admixtures. Very frequently the dyeingoperation is repeated twice, or even three times, with the understanding, how-ever, that it is in each case first followed by a thorough clearing, next a freshmordanting, and then again dyeing.

The clearing operation consists in boiling the dyed goods, under pressure,with soap and carbonate of potassa first; and next by a twice repeated boilingin solution of tin-salt and soap, or also, in addition thereto, carbonate ofpotassa. The chief adtion of these substances is, in this instance, confinedto the elimination of the yellow and other colouring matters present in thecloth, which previous to clearing always presents a deep brownish brick-red,and lacks the peculiar beauty and the bleuette appearance of genuine Turkey-red. The tin-salt adts undoubtedly, also, by causing the combination of a