444 The Art of Dyeing. 



Article VIII. 

 The Art of Dyeing. 

 {Continued from page 385.) 



GALLING THE CALICO. 



The application of the mordant to the calico commonly 

 precedes what is termed galling. In this case, the calico, 

 well bleached, but not mordanted, should be boiled with 

 nutgalls, or other substances, containing tannin ; and the 

 calico, in this instance, takes up a certain quantity of gal- 

 lic acid and tannin, and holds it so firmly, that washing 

 the calico with water cannot separate the tannin from it. 



The calico so treated should now be dipped in alum, or 

 iron mordant; it then acquires determinate colours, accord- 

 ing to the affinity of the matter employed in galling, and 

 the mordant. 



Other colouring matter also, as for example, yellow wood, 

 logwood, madder, &e. unite in the same way with the ca- 

 lico, and then with the mordant. 



In many printed colours, the galling becomes a principal 

 operation, which must precede the impregnation with the 

 alum mordant. I have not been able to convince myself 

 of the utility of this practice. 



It is certainly true, that a galled piece of calico, dipped 

 in a solution of alum, takes up more alumina from it than 

 an ungalled portion ; but in this way, the great object, 

 namely, dark, saturated, and clear colours is not obtained. 

 This gives only acetate of alumina, in which galling is quite 

 unnecessary. The moderate price of this mordant renders 

 it of more general use at present, than formerly, where 

 more alum must be employed. 

 • Galling is employed for madder-dyeing. 



A piece of yarn, first galled and then mordanted, becomes 

 reddish brown, while yarn, impregnated with acetate of 

 alumina, likewise dyed in the same solution with madder and 

 bran, appears clear red, and requires a separate cleaning 

 with soap and soda, in order to make them alike. Tannin 

 does not act more favourably. 



AFFINITY OF COTTON FOR DIFFERENT DYESTUFFS. 



When calico, well cleaned and mordanted, is boiled with 



