74 MR. SCHUNCK ON RUBIAN AND ITS PRODUCTS OF DECOMPOSITION. 
If the formula of rubianine be C3, rubiadine will differ from it by containing 
the elements of 7 equivs. of waterless. If the formula of rubiadine be C44 H15 On, then 
its formation would presuppose the splitting up of 1 equiv. of rubian into 1 equiv. of 
rubiadine, 1 equiv. of sugar and 7 equivs. of water, for 
C44 His Ou + Ci2 Hi2 Oi2+7HO=:C5e H34 O30. 
It appears therefore that the action of alkalies on rubian differs in its results from 
the action of acids only in one respect, that alkalies as well as acids give rise to the 
formation of five distinct products of decomposition, that four of these are in both 
cases perfectly identical, and that the fifth substance produced by the action of acids 
is replaced in the case of alkalies by another, which, though perfectly distinct, is so 
similar both in properties and composition, that it may be considered as in eveiy 
respect its equivalent. 
Action of Ferments on Rubian.— It has long been suspected by chemists that the 
colouring matter of madder owes its formation to some process of fermentation, but 
the exact nature of the process has hitherto remained unknown. Mr. Higgin first 
pointed out the fact, that a formation of colouring matter takes place even during 
the short period occupied in the process of dyeing, and he attributes it to the 
aetion of some albuminous substance contained in madder on xanthine. That some 
process of decomposition takes place on extracting madder with cold or tepid water 
and exposing the extract to a moderate temperature, is proved by the fact that the 
extract, if concentrated, becomes after some time thick and gelatinous ; and that the 
process of decomposition takes effect chiefly on the rubian is apparent, since the 
extract, after it has become gelatinous, is found to have lost its bitter taste and the 
greater part of its yellow colour. 
In order to prepare the peculiar substance contained in madder which has the 
property of effecting the decomposition of rubian, I proceed in the following manner. 
A quantity of madder having been placed on a piece of calico or fine canvas, there is 
poured on it for every pound of madder taken about four quarts of distilled water, 
which may be either cold or of a temperature of about 38° C. The latter temperature 
is preferable, as the water then percolates more rapidly. To the extract there is 
added, without any delay, about an equal volume of alcohol, which causes the separa- 
tion of a quantity of dark reddish-brown flocks. These flocks are allowed to settle, 
and the supernatant yellowish-brown liquid is decanted. Fresh alcohol is added to 
the flocks, which are then placed on a paper filter, and washed on the filter with 
additional quantities of alcohol, until the percolating liquid, which is at first strongly 
coloured, becomes almost colourless. This process of washing, which often lasts a 
long time, may be assisted by removing the mass from the filter and shaking it up 
with moderately warm alcohol. The substance on the filter has now the appearance 
of a dark reddish-brown mass, which when rubbed between the fingers produces the 
same granular feeling as coagulated caseine, the sliminess which characterized it on 
its first precipitation with alcohol having disappeared. Now this substance possesses 
