MR. SCHUNCK ON RUBTAN AND ITS PRODUCTS OF DECOMPOSITION. 445 
the fourth one which has not hitherto been observed. The three former are, — 1st, Ali- 
zarine ; 2ndly, the substance which in my former papers I have called alpha-resin, 
but to which I prefer giving the name of Rubiretine ; 3rdly, the substance which I 
formerly termed heta-resin, but I shall now call Verantine from Verantia, the name 
applied to madder in the middle ages. The fourth substance I shall denominate 
Ruhianine. 
The presence of alizarine in this mixture is indicated by the dark and beautiful 
colours which are produced when it is employed for dyeing a piece of mordanted cloth, 
and which contrast forcibly with the faint and dull tints produced by rubian. It may 
also easily be separated from the other substances by dissolving the mixture in 
alcohol, adding hydrate of alumina to the solution, filtering, treating the alumina 
compound repeatedly with a solution of carbonate of potash or soda, until nothing 
more is dissolved by the latter, decomposing the alumina compound with acid, and 
dissolving the residue in alcohol, when on evaporating the latter crystals of alizarine 
with its usual characters are obtained. In order however to obviate all objections 
which might arise from the use of alkalies in regard to the effect which the latter 
might be supposed to have in causing the formation of the alizarine, I determined if 
possible to use acids and salts only in the separation of the substances mentioned 
above. Of the four substances contained in the orange-coloured flocks, two, viz. aliza- 
rine and rubianine, are soluble in boiling water, and may thereby be separated froni 
the two others which are insoluble in water. This method of separation is however 
tedious, on account of the sparing solubility of alizarine and rubianine in boiling 
water. I therefore prefer using the following method. The orange-coloured flocks 
containing the four substances are treated with boiling alcohol, in which they dis- 
solve with a dark reddish-yellow colour. The alcohol is filtered boiling hot, and de- 
posits on cooling a small quantity of yellow crystalline particles, consisting chiefly of 
rubianine. The treatment with alcohol is repeated as long as the latter acquires a 
dark yellow colour. The greatest part of the rubianine remains behind as a yellow 
or brownish-yellow crystalline mass, which is treated repeatedly with boiling alcohol, 
in which the whole at last dissolves, the greatest part again separating on the solution 
cooling, either in yellow needles or as a brownish-yellow crystalline mass. If its colour 
is not a pure yellow, or if it is imperfectly crystallized, it contains verantine and must 
be purified. For this purpose the whole of the mass which has been deposited on the 
alcohol cooling, after being collected on a filter, is again dissolved in boiling alcohol, 
and sugar of lead is added to the solution, by which means the verantine is precipi- 
tated in combination with oxide of lead, while the rubianine remains in solution and 
is again deposited, when the solution, after being filtered boiling hot, is allowed to 
cool, in long, lemon-yellow silky needles, which may be rendered perfectly pure by 
recrystallization. The compound of verantine and oxide of lead may be decomposed 
with sulphuric acid,, and the verantine separated from the sulphate of lead by boiling 
alcohol. The alcoholic liquid from which the rubianine has been deposited contains 
3 M 
MDCCCLI. 
