48 On Madder, and 



madder-red is obtained in the form of a brownish-yellow 

 crystalline powder. 



Characters of Madder- Red. —These, as far as the dyer is 

 concerned, are as follow : When carefully heated in a glass 

 tube, madder-red melts into a dark orange-coloured liquid, 

 and, leaving some charcoal, is driven off in the form of 

 a yellow vapour, which condenses into bright orange- 

 coloured needles. By additional heat, the sublimate may 

 be driven along the tube without leaving any carbonaceous 

 residue, so that the first sublimed portion is not decom- 

 posed but is capable of a second sublimation. It colours 

 alum and iron mordanted cotton, as well as madder-red 

 itself. The red has more of a fire colour (mehr feuer) than 

 that of the unsublimed portion. Sublimed madder dissolves 

 in potash ley with a blue colour. 



In pure water the madder-red dissolves by heating, and 

 forms a dark-yellow solution. It is difficultly soluble in 

 cold water. A hot solution, on cooling, allows the madder- 

 red to precipitate partly in the form of orange-yellow flocks. 

 Acids change the dark-yellow solution into a bright-yellow. 



In well-water, and water containing lime, madder-red 

 dissolves with a purple-red colour, a blueish gum being 

 formed. Portions of alum-mordanted cotton, therefore, 

 exhibit no medium-red colour, but a dark, red-brown pur- 

 ple colour ; chalk acts in the same way, which affords a 

 sufficient distinction from madder-purple. 



Spirits, alcohol, and ether dissolve madder-red, forming 

 a reddish-yellow solution. After the evaporation of the 

 solution a brownish-yellow crystalline powder remains. 

 When water is added to a hot concentrated solution of 

 madder-red in alcohol, a quantity of silky crystals separate, 

 which swim in the liquid. 



Dilute acids dissolve madder-red, forming a yellow solu- 

 tion. On cooling orange-yellow flocks separate. 



Ammonia forms, with madder-red, a beautiful purple-red 

 solution, which, when printed on unmordanted cotton, and 

 washed, after drying in hot water, leaves a dark-red colour 

 without lustre. When printed (on cotton which has imbibed 

 the alum mordant) and then washed in boiling water, a dull 

 red is obtained. 



Potash ley dissolves madder- red, producing a beautiful 



