502 Dr. Schunck on Rubian and its Products of Decomposition. 



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 evaporation, 

 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 putrefac- 

 tion. 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 pre- 

 cipitate. This precipitate, after filtering and washing, was de- 

 composed with cold sulphuric acid ; the excess of sulphuric acid 

 was removed with carbonate of lead ; and after passing sulphu- 

 retted hydrogen through the filtered liquid to precipitate a little 

 lead contained in the solution, it was again filtered and evapo- 

 rated, 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 washed 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 emulsine 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 

 he fat had collected on the surface, and then precipitating the 

 emulsine from the clear liquid underneath, by means of alcohol. 



