MR. SCHUNCK ON RUBIAN AND ITS PRODUCTS OF DECOMPOSITION. 
81 
If this be the true composition of rnbiafine, 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 
2 equivs. of Sugar . . . =C ,4 O 24 I fCsg H 34 030 = 1 equiv. of Rubian. 
1 equiv. of Rubiafine . . =€32 H 13 O gj """I H 3 O 3=3 equivs. of Water. 
C'se H 37 tlas Csg H 37 O 33 
Ruhiacine and Rubiacic Acid . — In my former papers on madder, I have given for 
rubiacic acid the formula C 31 Hg Oig, and for rubiacine C 3 , Hg 0 , 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 carried 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 pernitrate 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 
pernitrate of iron until nothing more is dissolved. The resulting dark reddish-brown 
liquid is strained through calico, and acid is added to it, which produces a yellow 
precipitate. This is filtered, washed and dissolved in boiling carbonate of potash. 
The solution on cooling deposits crystals of rubiacate of potash, which are placed on 
a filter and washed with cold water. From a solution of the potash salt, the acid 
may be precipitated by muriatic or any other strong acid. Some rubiacic acid pre- 
pared in this manner was analysed with the following result ; — 
I. 0*3160 grrn. gave 0*7090 carbonic acid and 0*1010 water. 
In 100 parts it contained, therefore, — 
Carbon 61*19 
Hydrogen 3*55 
Oxygen’ 35*26 
In my former experiments I obtained as a mean of three determinations the fol- 
lowing numbers : — 
Carbon . 
Hydrogen 
Oxygen . 
57-28 
2*47 
40*25 
