68 REPORT—1848. 
ammonia. The ammoniacal solution gives purple precipitates with the chlo- 
rides of barium and calcium, and a dirty red precipitate with alum. It dis- 
solves in perchloride and pernitrate of iron with a dark reddish-brown colour, 
and is re-precipitated by acids in flocks. The alcoholic solution gives red 
precipitates with alcoholic solutions of sugar of lead and acetate of copper. 
If chlorine be passed through a solution of the resin in caustic potash, it is 
decolorized ; acids however now produce no precipitate, so that the resin 
seems to have been entirely decomposed by the chlorine. If mordanted 
cloth be introduced into boiling water, in which a quantity of the resin is 
suspended, the alumina mordant acquires an orange colour, and the iron 
mordant a brown colour. Nevertheless these colours are so slight, that itis 
not likely that this resin contributes in any way to produce the desired effect _ 
in the process of madder-dyeing. I shall presently show that, on the contrary, 
it is rather injurious than otherwise in this process, since those parts of the 
cloth which should remain white acquire from it a disagreeable yellow tinge, 
which cannot afterwards be removed by merely washing with water, so that 
even if it did contribute to produce any greater intensity of colour on the 
mordanted parts, the advantage would be more than counterbalanced by the — 
injurious effect on the unroordanted parts. j 
Beta-resin.—This resin also forms a constituent of the dark brown preci- 
pitate produced by acids in a decoction of madder. If this precipitate be 
treated with a boiling solution of perchloride or pernitrate of iron, the beta- 
resin forms a compound with peroxide of iron, which remains undissolved. 
By decomposing this compound with muriatie acid, and dissolving the resin 
in boiling alcohol, it is deposited on the alcohol cooling as a light brown f 
powder. It hardly melts at the temperature of boiling water, but merely 
becomes soft and coheres into lumps. When heated on platinum foil, it melts 
and burns, leaving a slight red ash. When heated in a glass tube, it gives 
yellow fumes and evolves a disagreeable smell, leaving a carbonaceous residue. 
It is slightly soluble in boiling water, to which it communicates a yellow 
tinge; on the solution cooling nothing separates, but on adding acid some — 
yellow flocks are deposited, while the liquid becomes colourless. The alco- 
holic solution is dark yellow; it reddens litmus-paper. Water renders it 
milky, and acids precipitate the resin completely in yellow flocks. The resin 
dissolves in concentrated sulphuric acid with a dark brown colour, and is re- 
precipitated by water in light brown flocks. Concentrated nitric acid dissolves 
it on boiling and decomposes it; on evaporation there is left a yellow, bitter 
astringent substance. It dissolves in caustic and carbonated alkalies with a — 
dirty red colour, inclining to purple in the case of caustic alkali. It is re-pre- 
cipitated by acids in brown flocks. If chlorine be passed through a solution 
of the resin in caustic potash, it is decolorized ; but the substance itself 
seems to be thereby decomposed, as acids afterwards produce only a slight 
precipitate. The ammoniacal solution gives with the chlorides of barium 
and calcium dirty yellow precipitates. The alcoholic solution gives with an 
alcoholic solution of sugar of lead a red precipitate, and with an alcoholic 
solution of acetate of copper a brown precipitate. The ammoniacal solution 
loses its ammonia on evaporation, and the resin is left as a transparent brown 
skin. This resin has the same effect on mordanted cloth as the preceding 
the alumina mordant acquires an orange, and the iron mordant a brown 
colour, while the unmordanted parts become yellow and unsightly. ‘These 
effects are not however so decided as in the case of the alpha-resin, which is _ 
probably owing to its being less soluble in water than the latter. 
Rubian.—I have given this name to the substance to which the bitter taste 
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