498 Dr. Schunck on Rubian and its Products of Decomposition. 



ferment, prevented the formation of alizarine, 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 rubiretine 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 quan- 

 tity of sugar. The remaining products of decomposition were 

 rubiafine, a trace of alizarine, and a large quantity of rubiretine 

 and verantine, but no rubiagine. 



From these experiments, which seem to me sufficiently decisive 

 to require no further confirmation, I draw the following in- 

 ferences : — 



1 . Theraexist 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 re- 

 tarded, the more rubiretine and verantine, and the less alizarine 

 are formed, so much so that in some cases the alizarine disap- 

 pears 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 fermentation, the action is, as regards its duration, if 

 not promoted, at all events not retarded ; and as regards the rela- 

 tive quantities of the various substances produced, the amount of 

 alizarine is thereby decidedly increased, while that of the rubire- 

 tine and verantine is diminished. 



