98 MR. SCHUNCK ON RUBIAN AND ITS PRODUCTS OF DECOMPOSITION. 
acetate of alumina, which produced a red precipitate. This precipitate, aftei filtration 
and washing with alcohol, was decomposed with muriatic acid, and the yellow flocks 
left by the acid were dissolved in alcohol, on the spontaneous evaporation of which 
there was left a mass of pure alizarine in well-defined yellow crystals. The liquid 
filtered from the alumina precipitate was evaporated to dryness, and the residue left 
was treated with water and muriatic acid, when a brown mass was obtained, which 
after filtering and washing was treated with cold alcohol. The alcohol left undis- 
solved a brown powder, consisting probably of verantine, and after filtration and 
evaporation left a brown resinous substance, easily fusible when thrown into boiling 
water, and consisting doubtless of rubiretine. The quantity of alizarine formed 
seemed to be mucli larger in proportion to the rubian employed, and to the quantity 
of other substances formed, than in the case of the ferment of madder. Nevertheless, 
I must state, that on repeating the experiment I was unable to attain the same 
result, the alizarine being formed in much smaller proportion and giving place to 
other products of decomposition. 
Lastly, I resolved to examine what effect, if any, would be produced on rubian by- 
seme fermentative substance derived like that of madder from a vegetable root. For 
this purpose I chose the albuminous substance described by Braconnot as existing 
in the root of the Helianthus tuberosus*. I selected this substance, because it has, 
like the ferment of madder, the property of causing a solution of sugar to undergo 
an acetous fermentation. It was prepared in the following manner. The tubers 
were cut into slices, then pounded in a mortar with a little water until the lumps had 
disappeared. The mass was then placed on a piece of calico, and the liquor expressed 
with the hands. The muddy liquid which ran through was then mixed with a con- 
siderable quantity of alcohol. This produced a gray precipitate, which was collected 
on a filter and well washed with cold alcohol. Some of this precipitate was then 
added to a solution of rubian, and the mixture was allowed to stand in a moderately 
warm place until it began to disengage a putrid smell. The liquid was then filtered, 
and evaporated to dryness. The residue was treated with boiling alcohol, which 
dissolved a part with a y^ellow colour, leaving undissolved a quantity of brown flocks, 
consisting probably of some of the ferment. The alcohol on evaporation left a residue, 
consisting of rubian with its usual appearance and properties, and apparently free 
from sugar. The substance left on the filter had acquired a brownish-yellow colour, 
which was not removable by washing with water. On being treated with boiling 
alcohol, it lost its yellow colour, which was now transferred to the alcohol. The 
alcohol after filtration and evaporation left a dark brown substance in the shape of a 
pellicle, which yielded nothing to boiling water. On being treated with cold alcohol, 
a brown powder resembling verantine was left undissolved, while the filtered liquid 
gave on evaporation a residue of a resinous nature, which melted when thrown into 
boiling water and became brittle again when cold, and consisted doubtless of rubire- 
* Ann. de Chem. et de Phys. xxv. 358. 
