MR. SCHUNCK ON RUBIAN AND ITS PRODUCTS OF DECOMPOSITION. 
91 
and rubiagine. The rubianine produced by acids, and the rubiadine formed by 
alkalies, give place, when ferment is the decomposing agent, to rubiafine and rubiagine. 
The rubiadipine, in consequence of the uncertainty of its nature and origin, and the 
minute quantity in which it is formed, I leave out of consideration. The relative 
proportion in which the various products of decomposition are formed, seems to be 
about the same in the case of ferment as when acids or alkalies are employed. Aliza- 
rine is formed in the smallest quantity; of rubiretine and verantine a little more is 
produced, but the sugar and the rubiafine and rubiagine exceed all the others in 
amount. 
It appears further from these experiments, that the ordinary process of dyeing 
with madder is, in fact, mainly a process of fermentation, that it consists essentially 
of a re-arrangement of the elements of rubian induced by the action of ferment, 
whereby a formation of colouring matter takes place, and that the precautions 
necessary to be taken in regard to the regulation of the temperature in madder 
dyeing have reference principally to the progress of the fermentation. The extra- 
ordinary rapidity with which this process of fermentation is completed, is the only 
circumstance which distinguishes it from other processes of a similar nature. 
A very interesting question now arises, suggested by the analogy which niust be 
presumed to exist between this and other processes of fermentation, viz. By what 
means is the action of the ferment on rubian either destroyed, retarded or promoted ; 
and do not any means exist of so modifying the action as to lead to the formation of 
particular substances in preference to others ? With the view of throwing some light 
on this question, I instituted a series of experiments, which I shall now proceed to 
describe. 
Having taken a solution of rubian and mixed it with a quantity of ferment suf- 
ficiently large to effect its decomposition under ordinary circumstances, I raised the 
temperature of the mixture to the boiling point and kept it boiling for a short time. 
After the mixture had stood for some days exposed to a moderate temperature, I 
found that the rubian had not undeigone the least change. The liquid remained 
yellow and bitter, and after filtration and evaporation left a residue of rubian with its 
usual appearance and properties. 
I took in the next place a quantity of ferment, dried it slowly at a moderate tem- 
perature, reduced it to a fine powder and mixed it with a solution of rubian. After 
the mixture had stood for some days, the rubian was enfii'ely decomposed. The 
filtered liquid left on evaporation a quantity of sugar, and the residual mass on the 
filter, which was interspersed with numerous small yellow crystals, was treated with 
boiling alcohol, which, after being filtered boiling hot and allowed to cool, deposited 
a large quantity of rubiafine in crystals. The alcoholic liquid, on being examined in 
the usual manner, was found to contain besides rubiafine, alizarine, rubiagine, rubi- 
retine and verantine, the two latter being rather less in amount than usual. 
After drying the ferment at a moderate temperature, then heating it for some hours 
