ACCESSORY OPERATIONS.

651

For light shades dilute the above with gum-water containing 100 grms. nitrateof lead per litre. After printing, the goods are hung up for a few hours inmoist air. They are then passed, for a minute or half a minute, into a chest,the air of which is strongly impregnated with ammonia, and next passed intoa bath containing 2'5 kilos, of corrosive sublimate per 1000 litres of water.Here they are left for twenty minutes, then washed in flowing water, and

passed anew into a bath containing—

Corrosive sublimate. 1 kilo.

Acetic acid, at 7° to 8° Baume . 1 „

Acetate of soda.500 grms.

Wash, and dry. If the pieces, after drying, are passed through a weak alkalinebath, the colour becomes more violet.

Operations Accessory to Dyeing.

Although the process of bleaching has been described in an earlier portionof this work (see pp. 44 and 87), there are a variety of subsidiary operations,both before and after dyeing, in the stridt sense of the term, which requireexplanation. As a preliminary, it will be needful to glance briefly at thedifferent states in which textile materials are submitted to dyeing, and whichhave been only incidentally mentioned.

Cotton is very rarely dyed in the unspun state, as cotton-wool. It is chieflydyed as yarn or spun thread, either in the hank or—in some cases—in the cop.The latter process, where practicable, is economical, as saving the time andlabour required for forming the yarn into hanks; but to cause the mordantsand dye-liquors to penetrate through a compadt cop, so that the colour pro-duced may be full and even, is very difficult. Cotton is comparatively rarelydyed in the woven state. Wool is operated upon by the dyer in a greaternumber of states. Very large quantities are dyed in the original, unspun,state: this is the case with the wool intended to be worked up into superiorqualities of broadcloth. The dye, under these circumstances, has full facilityfor adting thoroughly upon every fibre : hence wool-dyed colours are generallyconsidered the fastest, and the goods, other things being equal, fetch a higherprice than such as are dyed in the piece. In consequence, stratagems havebeen devised for giving to piece-dyed doe-skins, &c., the appearance of havingbeen dyed in the wool. In piece-dyed goods the listings are, naturally, of thesame colour as is the body of the piece. If, however, there be applied to thelistings some solution which may discharge the dye, and leave them eitherwhite or of a shade differing from that of the body of the piece, purchasersare led to suppose that the cloth has been dyed in the wool.

Wool-dyeing, besides superior fastness and penetration, has the advantagein evenness. Should any slight inequality, either of depth or of tone, occur,yet when the whole of the wool has been “scribbled” together such defectsdisappear, and the surface of the woven cloth will be found to exhibit a colourabsolutely alike in all parts. To counterbalance these advantages great careis required that the pieces may not become soiled in any of the operationssubsequent to dyeing. The chief practical difficulty in wool-dyeing is to pre-vent the mass from becoming felted together, so as to be unfit for carding andspinning. In wool-dyeing care should also be taken to present the wares in asuitable form. If ground or chipped dye-woods, orchil-paste, &c., are used,