68 MR. SCHUNCK ON RUBIAN AND ITS PRODUCTS OF DECOMPOSITION. 
which is a compound of alizarine and verantine with alumina, is decomposed with 
muriatic acid, and the alizarine and verantine are separated from one another by 
means of acetate of copper, and purified in the manner which 1 have before described, 
when treating of the products of decomposition with acids. The liquid filtered from 
this alumina compound is still yellow. On adding to it sulphuric acid and a large 
quantity of water, the substances dissolved in it are precipitated in the shape of yellow 
flocks, which after filtration and edulcoration are redissolved in boiling alcohol. On 
adding acetate of lead to this solution, there is produced a dark purplish-brown pre- 
cipitate, which consists of rubiretine and verantine in combination with oxide of 
lead. The liquid still remains yellow, and is filtered from the precipitate. The 
latter, on being decomposed with boiling muriatic acid, gives a brown powder, which, 
after filtration and edulcoration, is treated with cold alcohol. This dissolves the 
rubiretine, leaving behind the greatest part of the verantine. The alcoholic liquid, 
after filtration and evaporation, leaves a residue of rubiretine with its usual appear- 
ance and properties. Should it not melt easily when thrown into boiling water, it 
must again be treated with a small quantity of cold alcohol, when an additional 
portion of verantine remains undissolved, and the alcohol on evaporation usually 
gives pure rubiretine. Should it, however, still contain verantine, the process of 
treating with cold alcohol must be repeated, until it is free from that substance. The 
alcoholic liquid filtered from the lead precipitate contains the substance which I 
call rubiadine. In order to obtain it in a state of purity, water is added to the solu- 
tion. This produces a yellow precipitate, which after filtration is treated with just 
sufficient boiling alcohol to dissolve it. To the solution while boiling, there is added 
hydrated oxide of lead, which takes up the impurity, consisting chiefly of rubiretine, 
and renders the solution of a lighter yellow. The liquid, after being filtered boiling 
hot, deposits the rubiadine on cooling in small yellow needles. An additional quan- 
tity may be procured by evaporating the mother-liquor, but this portion is not 
sufficiently pure to assume a crystalline form, and has the appearance of an amor- 
phous yellow powder. By exposing it to heat, however, a crystalline sublimate of 
rubiadine may be obtained. 
The acid liquid filtered from the mixture of the four preceding substances still 
contains in solution another product of decomposition. After neutralizing the sul- 
phuric acid with carbonate of lead, and evaporating the filtered liquid to dryness, a 
residue is left, which is treated with alcohol. This leaves undissolved the sulphate 
of soda, and after filtration and evaporation gives a brown glutinous mass, which 
has all the properties of the sugar produced by the action of acids on rubian. It is 
this sugar, which, by the continued action on it of the caustic alkali, gives rise to the 
formation of the dark brown flocculent substance, insoluble in alcohol, which is found 
mixed with the four preceding products of decomposition. This fact is sufficiently 
proved by the composition of the latter substance, which is identical with that of the 
brown substance produced by the action of strong acids on ordinary sugar. 
