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



composition of rubiafine is different, and as I have succeeded in 

 again preparing a substance of the same composition as the rubia- 

 cine formerly obtained, they must be considered as distinct bodies. 



I am unaole to give more than one analysis of rubiafine, which 

 yielded the following numbers : — 



0-1765 grm., dried at 100° C, gave 0-4485 carbonic acid and 

 0-0725 water. 



The relation in which rubiafine stands to rubiacic acid proves 

 that the former contains 32 atoms of carbon. Its composition 

 must then be as follows : — 



277 10000 10000 



If this be the true composition of rubiafine, then the latter 

 stands in the same relation to rubian as rubianine and rubiadine, 

 from which, if the latter also contain 32 atoms of carbon, it only 

 differs by the elements of water. If to rubian be added 3 equivs. 

 of water, there are given the elements of 1 equiv. of rubiafine, 

 and 2 equivs. of sugar, for 



2eqs.of Sugar = C^m^'^O^'^ \ _ rC^R^O^=l eq.of Rubian. 

 leq. of Rubiafine srC^^uisQ 9/ " \ H ^0 3 = 3eqs. of Water. 



C56H37033 Qb6^37Q33 



. Rubiacine and Rubiacic Acid. — In my former papers on 

 madder, 1 have given for rubiacic acid the formula C^' H^ 0^^, 

 and for rubiacine C^^ H^ 0^®. In order to ascertain the correct 

 formula, and also to determine the relation in which they stand 

 to rubian and rubiafine, of which they must be derivatives, I 

 prepared and submitted to analysis a fresh quantity of these 

 substances. For the purpose of preparing rubiacic acid, it is 

 not necessary to take madder itself. If any dyework is at hand 

 in which madder-dyeing is can-ied on, the liquor in which the 

 goods have been immersed, together with the madder, and which 

 is generally allowed to run to waste, may be employed. This liquid 

 contains a considerable quantity of some substance, which by the 

 action of pemitrate of iron may be converted into rubiacic acid. 

 The mode of operation is as follows. To the liquid, which is 

 brown and muddy, there is added, after the separation of the 

 woody particles of the madder, a quantity of muriatic acid, which 

 gives a brown flocculent precipitate, while the liquid becomes 

 clear and colourless. This precipitate, after being collected on 

 a calico strainer, is treated with pemitrate of iron until nothing 

 more is dissolved. The resulting dark reddish-brown liquid is 



