452 The Art of Dyeing , \ 



Article VIII. 



The Art of Dyeing. 



(Continued from page 375.) 



When calico printed with iron and copper mordant is 

 dipped in a solution of 1 lb. ferro-prussiate of potash and 

 40 lbs. water, it acquires a dark brown colour, from the 

 production of ferro-prussiate of copper. 



Except in the case of logwood colours there appears to 

 be no advantageous action from this relation of cotton 

 mordanted with iron mordant to copper mordant. Its 

 influence is rather deteriorating. Thus a cochineal blueish 

 gray, with iron alum is not obtained, but a violet colour, 

 when the calico is treated with copper mordant in the 

 manner described, before dyeing with the cochineal. When 

 lighter grounds which have iron for their basis, after dyeing 

 are immersed in copper mordant, No. 2, various shades of 

 colour are obtained of greater permanence, although with 

 most of the dark colours of compounds containing iron, the 

 changes are not so remarkable as in the colours with alum 

 mordant. 



ON THE ACTION OF DIFFERENT ADJUNCTS IN DYEING WITH 

 MADDER, QUERCITRON, AND LOGWOOD. 



1. Madder with starch, flour and bran. — When the alum 

 mordant to be printed is thickened with starch, the madder 

 red produced by it comes out clearer than when the thick- 

 ening medium is gum. This fact might lead us to the 

 suspicion that the clearing action of bran depends on the 

 proportion of starch in it. Starch was therefore added to 

 a solution of madder, and dyeing performed as on the 

 addition of bran. 



The result was different from what ♦might have been 

 anticipated. The addition of starch deteriorated the action. 

 In the proportions of 1 lb. starch, 12 lbs. madder, and 12 

 lbs. mordanted cloth, the colour produced was much the 

 same as when no starch was added. With 3 lbs. starch to 

 12 lbs. madder, the colour was considerably paler. On the 

 edge of the dye pot a pasty looking matter was deposited, 

 and much red varnish swam on the surface of the solution. 

 As the red varnish is neither produced by the use of bran 



