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SELECTED ARTICLES. 
placed under the receiver of an air pump, left a deep yellow 
residuum in the form of lamellae, or of minute scales having a 
crystalline aspect. 
This residue weighed 7.3 grammes, it constituted the yellow 
matter, or the yellow resin, the rhabarbarine or rheine, of 
some chemists. 
Traces of rheine with fixed oil. This product dissolved 
in boiling water, became turbid when cooled, and formed a 
yellow powder. It volatilized in the form of vapour, or aro- 
matic yellow fumes, its taste was styptic, pungent rather than 
bitter; dissolved in sulphuric ether or alcohol, it produced 
golden yellow solutions, and left upon blotting paper a stain 
which could not be totally removed by heat, and which was 
due to a small quantity of fixed oil. 
Note. I am at a loss to know if there exists with the co- 
louring matter a volatile oil, which gives it the aromatic odour; 
or whether this odour belongs really to the rheine itself. 
This yellow matter is but slightly soluble in sulphuric, 
acetic, and muriatic acids. Treated by boiling nitric acid, it 
undergoes alteration, and produces a brownish yellow sub- 
stance, which contains no oxalic acid, and is but partially solu- 
ble in water. The action of soda, potassa, and ammonia upon 
rheine is marked; they dissolve it, and afford solutions of a 
beautiful reddish purple colour, which probably may be useful 
in dyeing. If these purple solutions are saturated with an acid, 
the liquid assumes a yellow colour, thickens, and throws down 
yellow flocculi. 
The aqueous solutions of rheine produce with 
Hydrochlorate of baryta a yellowish precipitate, 
Acetate of lead a rose coloured precipitate, 
Per-muriate of iron a black colour, 
Protochloride of tin a yellowish white deposit, 
Alum a yellow tint. 
2. After the treatment by ether, I submitted the powder to 
the action of alcohol and pure cold water. In the second in- 
