MR. SCHUNCK ON RUBIAN AND ITS PRODUCTS OF DECOMPOSITION. 97 
tion, left a reddish, deliquescent residue similar to the last. It appears, therefore, 
that the action of albumen on rubian is but slight. 
In order to ascertain what effect caseine has on rubian, I mixed a solution of the 
latter with a quantity of milk, and allowed the mixture to stand in a warm place for 
several days, until the smell indicated that the caseine had entered into a state of 
putrefaction. The liquid, which was still yellow and bitter, was filtered from the 
caseine, which had separated in yellow flocculent masses, and basic acetate of lead 
was added, which produced a red precipitate. This precipitate, after filtering and 
washing, was decomposed with cold sulphuric acid ; the excess of sulphuric acid was 
removed with carbonate of lead ; and after passing sulphuretted hydrogen through 
the filtered liquid to precipitate a little lead contained in the solution, it was again 
filtered and evaporated, when it left a quantity of rubian possessing the usual pro- 
perties of that substance, with the exception of its being somewhat viscid. The 
caseine on the filter after being w^ashed with water was treated with boiling alcohol, 
which deprived it of its yellow colour, and rendered it white. The filtered liquid, 
which was yellow, gave no precipitate either with acetate of alumina or sugar of lead, 
proving the absence of alizarine and the usual products of decomposition of rubian. 
On evaporation it left a residue of rubian mixed with fat, the whole, with the exception 
of the fat, being soluble in water. 
A similar negative result was obtained with gelatine and yeast. A solution of 
rubian being mixed with a solution of glue, the mixture after standing for several 
weeks began to emit a putrid smell, and acquired a reddish tinge, but remained 
bitter, and deposited nothing insoluble. On adding yeast to a solution of rubian, 
and allowing to stand until putrefaction commenced, no apparent change took place 
in the solution, which retained its yellow colour and bitter taste. 
The action of emiilsine on rubian was very different. The emulsine employed was 
prepared in the usual manner, by treating sweet almonds, after being pounded and 
pressed between paper to deprive them of their oil, with water, separating the milky 
liquid from the residue by straining, allowing it to stand until the fat had collected 
on the surface, and then precipitating the emulsine from the clear liquid underneath, 
by means of alcohol. Some emulsine prepared in this manner was placed in a solu- 
tion of rubian, and well mixed up with it. The mixture was allowed to stand in a 
warm place for some days. By degrees the liquid became almost colourless, while 
the emulsine acquired a yellow colour. It was filtered and evaporated, when it left 
a quantity of emulsine. The yellow mass on the filter was treated with boiling 
alcohol, which became yellow, while the residue lost almost the whole of its colour. 
The alcoholic liquid was filtered and spontaneously evaporated, when it left a 
yellowish-red mass, among which crystals of alizarine were discernible. This mass 
was treated with cold water, in which a part dissolved with a yellow colour. The 
liquid after filtration and evaporation left a quantity of unchanged rubian. The part 
insoluble in water was dissolved again in alcohol, and to the solution was added 
