A Manual of the Chemistry of the Carbon Compounds

TEJS CARBON COMPOUNDS. 463
yields opianic acid, and this body is converted into rafiopine by
heating it with concentrated sulphuric acid to 180°:—
fOCH, CO
COH + 6H£04 = CflHB(OH)/1-1 >C9H2(OH)2 +
tCO.OH
X CO'
3COS + 5SO2 + 9H2O
Eufiopin is sparingly soluble in hot water, and separates from it in
small yellow needles, and from alcohol in indistinct yellowish-red
crystals. In alkalis it dissolves with a red colour, and with ammonia
it forms a reddish-brown solution Calcium chloride gives with
these solutions a reddish-violet, and barium chloride a violet precipitate.
On mordanted cloth it dyes colours lesembling those produced
by alizarin.
HEXOXYANTHKAQUIKONE, OK KUFIGALLJC ACID, C0HjO"4(OH)e.
When gallic acid is heated with sulphuric acid in a water-bath, the
liquid assumes a dark purple colour, and on adding water, a red crystalline
precipitate of rufigallic acid is obtained, which on heating sublimes
in yellowish-red needles. Concentrated potash colours it blue,
and on addition of water it dissolves with a violet colour. It dyes
mordanted cloth like alizarin, but the colours are not very brilliant.
By fusing it with potash it is resolved into oxyquinone and foiroie
acid:—
.CO
C8H(OH)8