92 MR. SCHUNCK ON RUBIAN AND ITS PRODUCTS OF DECOMPOSITION. 
in a water-bath, before adding it to a solution of rubian, no apparent change took 
place for some time, but gradually the rubian began to disappear, and after two 
months was entirely decomposed. The filtered liquid left on evaporation a quantity 
of sugar, and the residue on the filter, on being treated with alcohol, yielded a solution 
which contained rubiafine, and a pretty large quantity of rubiretine and verantine, 
but no alizarine. 
To a solution of rubian I now added a sufficient quantity of ferment to effect its 
decomposition when used alone, and then a small quantity of sulphuric acid. The 
mixture remained apparently unchanged for some time. The liquid was filtered, the 
acid was neutralized with carbonate of lead, the liquid was then again filtered, and 
left on evaporation a yellowish-red, bitter, glutinous substance, which was appaiently 
a mixture of rubian and sugar. The mass left on the filter was treated with boiling 
alcohol, which was then found to contain a trace of alizarine, a little rubiagine, and a 
large quantity of rubiretine and verantine. 
The same experiment was performed, substituting for the sulphuric acid a minute 
quantity of carbonate of soda. This had the effect of completely dissolving the 
ferment, forming a solution to which the rubian imparted a red colour. After stand- 
ing for some time, the rubian was entirely decomposed, for on neutralizing the soda 
with sulphuric acid, a yellow precipitate fell, while the liquid became colouiless. 
The latter being filtered, the acid was neutralized with carbonate of lead, and the 
liquid being again filtered left on evaporation a quantity of sugar mixed with sulphate 
of soda. The mixture of ferment with the products of decomposition yielded to 
boiling alcohol a large amount of rubiafine, rather more than the average quantity of 
alizarine, and a moderate quantity of rubiretine and verantine, but no rubiagine. I 
repeated this experiment, using caustic soda instead of carbonate of soda ; but having 
employed rather too large a quantity of alkali, I found that the action of the ferment 
was very much retarded, so much so that after standing for some days there was still 
a quantity of undecomposed rubian present ; and among the products of decomposition 
formed there was little or no alizarine, rubiafine or rubiagine, but a large quantity of 
rubiretine and verantine. The addition of lime water produced a similar effect to 
that of carbonate of soda, though of not quite so marked a character. 
Having mixed a solution of rubian with ferment in the usual manner, I added a 
small quantity of sugar of lead. The ferment, which had been previously diffused 
through the liquid, was immediately precipitated by the lead salt in brown flocks, 
leaving a clear yellow solution floating above it. After standing however for some days 
the colour of the solution became gradually paler, and at length almost disappeared. 
After filtration and evaporation it left a small quantity of sugar. The mass left on 
the filter was purple, and contained oxide of lead. It was treated with cold sulphuric 
acid, which turned it red. The acid liquid after filtration was neutralized with 
carbonate of lead, and again filtered, when it appeared colourless, and produced no 
precipitate with basic acetate of lead, a proof that it contained no rubian. The mass 
