366 Dr. Schunck on Rubian and its Products of Decomposition. 



Kubianine. — This substance, as I mentioned before, has not 

 hitherto been observed among the bodies derived from madder. 

 It greatly resembles rubiacine in its appearance and many of its 

 properties ; it may however easily be distinguished by several 

 characteristics, and above all by its composition. It is obtained 

 from a solution in boding alcohol in the form of bright lemon- 

 yellow, sdky needles, which, when dry, form an interwoven 

 mass. It is soluble in boiling water, more so in fact than any 

 of the products of decomposition hitherto mentioned. It cry- 

 stallizes out again on the solution cooling in yellow silky needles. 

 It is less soluble in alcohol than the preceding substances. Its 

 colour is lighter than that of rubiacine. When heated on pla- 

 tinum-foil it melts to a brown liquid, then burns, leaving a car- 

 bonaceous residue, which on further heating disappears entirely. 

 When heated in a glass tube it gives a small quantity of a 

 yellow crystalline sublimate, but not by far so large a quantity 

 as is obtained under the same circumstances from rubiacine, 

 which, when carefully heated, may be almost entirely volatilized. 

 It is soluble in concentrated sulphuric acid with a yellow colour ; 

 the solution on boiling becomes black and gives off sulphurous 

 acid. A solution of rubiacine in concentrated sulphuric acid, re- 

 mains quite unchanged on boiling. It is not affected either by 

 dilute or concentrated nitric acid, even on boiling ; it merely 

 dissolves in them, and crystallizes out again on the acid cooling, 

 just as from boiling water. When treated in the cold with a solu- 

 tion of carbonate of potash or soda, or liquid ammonia, it does 

 not dissolve, nor is its colour at all changed. When the liquid is 

 boded, it dissolves however with a blood-red colour. Neverthe- 

 less it cannot be said to combine with the alkali, but merely to 

 be dissolved by it ; for on allowing these solutions to stand for 

 some time, a yellow crystalline mass again separates, which 

 is nothing but the substance itself. The ammoniacal solution 

 gives red precipitates with the chlorides of barium and calcium. 

 The alcoholic solution gives no precipitate with sugar of lead, 

 whereas a solution of rubiacine gives a dark red precipitate with 

 sugar of lead. It dissolves in a concentrated solution of per- 

 chloride of iron with a dark brown colour, but is not thereby 

 converted into rubiacic acid. It communicates to mordanted 

 cloth only a slight tinge of colour, similar to that produced by 

 rubiacine. 



Its analysis gave the following results : — 



I. 0*3520 grm. substance, dried at 100° C. and burnt with 

 chromate of lead, gave 0*7400 carbonic acid and 0*1750 water. 



II. 0-3805 grm. of the same preparation gave 0*7990 car- 

 bonic acid and 0*1890 water. 



III. 0*3965 grm. of another preparation gave 0*8330 car- 

 bonic acid and 0*1890 water. 



