134 TEXTILE FABRICS. [V. 



It is then boiled with muriatic acid, washed with cold water, 

 dissolved in alcohol, and the solution evaporated, when it de- 

 posits the pigment. It is, lastly, dissolved in ether several 

 times, and separates from it by evaporation. It is a cherry- 

 red powder, insoluble in cold water, rather soluble in hot, 

 very soluble in alcohol and ether ; soluble in alkalies with 

 deep-red color, and reprecipitable by acids. It fuses by heat, 

 and sublimes with partial decomposition, condensing in the 

 form of red needles, which dissolve in alkalies with a violet 

 color. Its composition is expressed in the formula C^Ji^^O^y 

 Both madder-purple and madder-red dissolve in cold oil of 

 vitriol, with a brilliant red color, and are again precipitated 

 unchanged by the addition of J its volume of water. Hence, 

 in preparing garancine, the oil of vitriol should be diluted 

 with ^ its volume of water, which would not dissolve the 

 colors, while it chars the woody fibre. 



Madder-red is contained in the precipitate which sepa- 

 rates from a cooling decoction of madder. After repeated 

 purification, it is a yellow powder, difiicultly soluble in water, 

 readily soluble in alcohol and ether, soluble in potassa with a 

 violet, in ammonia with a red color, sublimes at 437°, and 

 deposits orange-yellow needles. Both the sublimed and the 

 unsublimed appear to have the same composition, expressed by 

 the formula C^jjIIgOg. The red appears to pass into the pur- 

 ple by taking up 1 eq. water and 5 eq. oxygen. CggllgOg-f 

 H0+03=C,3H,„0,,. 



Schunck performed a series of experiments on madder root, 

 from the aqueous extract of which he obtained alizarin, ruhia- 

 cin, a and j8 resins, a bitter principle rubian, pectic and ruhiacic 

 acids, and a dark-brown substance. After thorough extraction 

 by water, and then by hydrochloric acid, which removed lime 

 and magnesia, he obtained by extraction with potassa, alizarin, 

 pectic acid, i3 resin, and probably rubiacic acid. Alizarin has 

 the formula Cj^H^O^+SHO, soluble in pure water with a yellow 

 color, in alcohol and ether ; soluble in caustic and carbonated 

 alkalies, with a brilliant purple color ; the potassa solution is 

 precipitable by alumina, which becomes reddish-purple ; by 



