438 CALICO-PRINTING. 



cles were from time to time omitted or changed, until at length the 

 simple mixture of alum and acetate of lead was found to answer 

 as a mordant, equally with compositions morn complicated. 



After the mordants have been applied, the cloth must be com- 

 pletely dried. It is rroper for this purpose to employ artificial 

 heat, which will contribute something -towards the separation of 

 the acetous acid from its base, and towards its evaporation, by 

 which the mordant will combine in a greater proportion, and more 

 intimately with the cloth. 



When the cloth is sufficiently dried, it is to be washed with warm 

 water and cow. dung, till all the flour, or gum, employed to thicken 

 the mordants, and all those parts of the mordants which are un 

 combined with the cloth, are removed. The cow. dung serves to 

 entangle these loose parts of the mordant?, and to prevent them 

 from combining with those parts of the cloth which are to remain 

 white. After this, the cloth is thoroughly rinsed in clean water. 



Almost the only dye-stuffs employed by calico-printers are in- 

 digo, madder, and quercitron bark, or weld. This last substance, 

 however, is but little used by the printers of (his country, except 

 for delicate greenish yellows. The quercitron bark has almost 

 superseded it, because it gives colours equally good, and is much 

 cheaper and more convenient, not requiring so great a heat to fix 

 it. Indigo, not requiring any mordant, is commonly applied at 

 once, either with a block or a pencil. It is prepared by boiling 

 together indigo and potash made caustic by quick lime, and orpi. 

 nient; the solution is afterwards thickened with gum. It must be 

 carefully secluded from the air, otherwise the indigo would soon 

 be regenerated, which would render the solution useless. Dr. 

 Bancroft has proposed to substitute coarse brown sugar for orpi- 

 ment : it is equally efficacious in decomposing the indigo, and 

 rendering it soluble ; while it likewise serves all the purposes of 

 gum. 



Let us now give an example or two of the manner in which the 

 printers give particular colours to calicoes. Some calicoes are 

 only printed of one colour, others have two, others three or more, 

 even to the number of eight, ten, or twelve. The smaller the 

 number of colours, the fewer in general are the processes. 



1. On oi the most common colours on cotton prints is a kind 

 of nankeen yellow, of various shades down to a deep yellowish 

 brown, or drab. It is usually in stripes or spots. To produce it, 



