96 MR. SCHUNCK ON RUBIAN AND ITS PRODUCTS OF DECO.MPOSITION. 
In the first part of this paper I have pointed out the possibility which exists in 
theory of converting rubian entirely into alizarine, to the exclusion of every other 
product of decomposition ; and though I cannot say that I have approached much 
nearer to its practical realization, still if, as the expenments just described prove, 
the fermentative process whereby alizarine is formed is of so plastic a nature as to 
be capable of yielding under different circumstances, sometimes more, sometimes 
less, occasionally none, of the latter substance, then the prospect of our being able 
so to modify it as to lead to the formation of a much larger quantity of alizarine 
from a given quantity of rubian than is at present possible, becomes less distant. 
The experiments which I shall now describe were made in order to ascertain the 
effect produced on rubian by other fermentative substances besides that contained in 
madder itself. 
I first took a solution of rubian and mixed it well with a solution of albumen made 
from white of egg. The mixture was allowed to stand in a moderately warm place 
for two months, but though the albumen had entered into a state of putrefaction, 
the rubian was still for the most part undecomposed, as was evident from the taste 
and colour of the liquid. At the bottom of the vessel there was found a small 
quantity of a dark reddish-brown deposit, which was collected on a filter. On treat- 
ing this deposit with boiling alcohol, the latter acquired a red colour, and left on 
evaporation a small quantity of a yellow bitter substance, soluble in water, which 
only differed from rubian in being somewhat viscid. The remainder of the dark 
brown deposit I treated with a mixture of muriatic acid and alcohol, when it imme- 
diately became, almost white, while the substance which had coloured it dissolved in 
the alcohol with a yellow colour. The alcohol was filtered from the insoluble part, 
which was probably merely modified albumen, and evaporated to dryness, when it 
left a reddish-yellow, uncrystalline residue. This residue was impure alizarine, for 
it gave on being heated in a tube a crystalline sublimate, it dissolved in caustic 
alkali with a violet colour, and its alcoholic solution became purple on the addition 
of acetate of copper. In the reddish-brown deposit it was doubtless contained in 
combination with some base, perhaps lime. The greatest part of the rubian remained 
in solution mixed with the albumen. The solution was slowly evaporated to dryness, 
when it left a red transparent substance like gum or varnish, which was treated with 
boiling alcohol. The alcohol acquired a reddish-yellow colour, and left on evapora- 
tion a yellowish-red, deliquescent, bitter residue, consisting apparently of rubian 
mixed with some nitrogenous substance. It was entirely soluble in water with a 
reddish colour. This solution gave with acetate of lead a copious brown precipitate, 
the supernatant liquid being almost colourless, but with acids and alkalies it gave 
the usual reactions of a solution of rubian. The greater part of the gum-like sub- 
stance was of course insoluble in alcohol. On being treated with a mixture of 
sulphuric acid and alcohol in the cold, an additional quantity of yellow liquid was 
obtained, which after filtration, neutralization with carbonate of lead and evapora- 
