94 
MR. SCHUNCK ON RUBIAN AND ITS PRODUCTS OF DECOMPOSITION. 
alizarine disappears entirely from among the products of decomposition, which then 
consist almost solely of rubiretine and verantine. The formation of rubiafine and 
rubiagine is promoted when the action of the ferment is moderately retarded, but 
diminishes again, or entirely ceases when the retardation is very great. Of the two, 
the rubiagine is the first to disappear when any retardation takes place. 
4. By the addition of small quantities of alkalies during the process of ferment- 
ation, the action is, as regards its duration, if not promoted, at all events not retarded ; 
and as regards the relative quantities of the various substances produced, the amount 
of alizarine is thereby decidedly increased, while that of the rubiretine and verantine 
is diminished. 
These experiments also confirm the view derived from analytical results, that there 
is a mutual relation and interdependence on the one hand between rubiretine and 
verantine, and on the other between rubiafine and rubiagine and the sugar, whereas 
alizarine occupies an independent position ; for rubiretine is never found among the 
products of decomposition by fermentation without an accompaniment of verantine, 
though both may be present to the exclusion of all other products ; and the formation 
of sugar always indicates that of rubiafine or rubiagine, whereas all these substances 
may be present without a trace of alizarine being at the same time produced. 
The deleterious effect resulting from the presence of acids in the dye-bath during 
the process of madder dyeing hereby finds an additional explanation. Not only do 
acids act injuriously by seizing hold of the mordants with which the colouring mattei 
ought to combine, not only do they allow the constituents of the root which are 
injurious in the process to have full scope by depriving them of the alkalies or alka- 
line earths with which they would otherwise unite, but they also retard the peculiar 
process by which the alizarine is formed, and even lead to the formation of delete- 
rious substances at the expense of the colouring matter itself. 
In order to place in a more striking light the influence exerted respectively by 
acids and alkalies during the process of the fermentation of rubian, I will here give 
the results of an experiment to ascertain quantitatively the amount of the various 
products of decomposition formed on the addition of either during the process. For 
this purpose I took 5’59 grms. rubian, dissolved it in water, added to the solution a 
quantity of ferment, and mixed both together very well. I then divided the mixture 
into two equal parts, and added to one half a small quantity of carbonate of soda, to 
the other a little sulphuric acid. Both were allowed to ferment for a length of time, 
and the portion insoluble in water was treated in both cases with boiling alcohol. 
The alcohol deposited on being filtered boiling hot a quantity of rubiafine, which was 
collected on a filter and weighed. To the alcoholic liquid I added acetate of alumina. 
The precipitate thereby occasioned was separated by filtration, washed with alcohol 
and decomposed with boiling muriatic acid. The red flocks thus obtained were col- 
lected on a filter, washed, dried and weighed. They consisted of alizarine, veran- 
tine and rubiafine. After being weighed, they were treated with boiling dilute nitric 
