MR. SCHUNCK ON RUBIAN AND ITS PRODUCTS OF DECOMPOSITION. 
93 
which had been treated with cold sulphuric acid, was then treated with boiling 
alcohol, which on being filtered and allowed to cool deposited some crystallized 
rubiafine, and was found to contain a trace of alizarine and a large quantity of rubi- 
retine and verantine. It appears therefore that even sugar of lead, which produces 
an insoluble compound with the ferment,, is incapable of arresting the action of the 
latter on rubian. 
The same experiment was made, using corrosive sublimate instead of sugar of lead. 
The action of the ferment was in this case considerably retarded, for the yellow 
colour of the liquid did not entirely disappear, even after several days. The filtered 
liquid left on evaporation some corrosive sublimate with a little rubian, but no sugar. 
The mass on the filter was treated with boiling alcohol, which was then found to 
contain no alizarine, rubiafine or rubiagine, but a considerable quantity of rubiretine 
and verantine. 
Arsenious acid had a very similar effect to sugar of lead and corrosive sublimate, 
that is to say, it retarded the action of the ferment, prevented the formation of aliza- 
rine, and promoted that of rubiretine and verantine. 
The addition of a large quantity of alcohol to a mixture of rubian and ferment had 
likewise the effect of retarding, though not of altogether preventing the fermentation. 
A great part of the rubian remained undecomposed, while the remainder had given 
rise to the formation of a small quantity of alizarine and a large quantity of rubi- 
retine and verantine. 
A solution of rubian having been mixed with ferment, I poured the mixture into a 
bottle, and then added a quantity of oil of turpentine, after which the whole was 
well shaken up and left to stand. The decomposition of the rubian was much 
retarded, and took several days for its completion. The oil of turpentine floating on 
the surface was removed. The liquid underneath was colourless. After filtration 
and evaporation it left a quantity of sugar. The remaining products of decomposi- 
tion were rubiafine, a trace of alizarine, and a large quantity of rubiretine and veran- 
tine, but no rubiagine. 
From these experiments, which seem to me sufficiently decisive to require no 
further confirmation, I draw the following inferences: — 
]. There exist no means, short of the complete destruction of the ferment, capable 
of arresting its action on rubian, except exposing it while in a moist state to the 
temperature of boiling water. Even when exposed to that temperature, after having 
been previously dried, its fermenting power is not entirely lost, but merely weakened. 
2. By the addition of various substances, usually classed as antiseptic, such as 
sulphuric acid, arsenious acid, sugar of lead, corrosive sublimate, alcohol and oil of 
turpentine, during the process of fermentation the action of the ferment is not 
destroyed ; it is merely retarded and modified. 
3. The more the action of the ferment on rubian is retarded, the more rubiretine 
and verantine, and the less alizarine are formed, so much so that in some cases the 
MDCCCLIII. o 
