446 MR. SCHUNCK ON RUBIAN AND ITS PRODUCTS OF DECOMPOSITION. 
the three other substances besides a portion of the rubianine. By adding acetate of 
alumina to it, the whole of the alizarine as well as a part of the verantine are preci- 
pitated, in combination with alumina, in the shape of a dark red powder, while the 
liquid retains a dark brownish-red colour. This precipitate, after being collected on 
a filter and washed with alcohol until the latter runs through colourless, is decom- 
posed with muriatic acid, which dissolves the alumina, leaving behind red flocks con- 
sisting of alizarine and verantine. These flocks, after being filtered off and washed 
with water, are again dissolved in alcohol, to which is then added a solution of neu- 
tral acetate of copper. This instantly changes the colour of the liquid to a beautiful 
dark purple. The copper compound of alizarine remains dissolved, while the veran- 
tine is entirely precipitated, in combination with oxide of copper, as a dark reddish- 
brown powder. The dark purple liquid, after filtration and evaporation, leaves a 
purple mass of alizarine-oxide-of-copper, which is decomposed with muriatic acid. 
Yellow flocks, consisting of alizarine, remain behind, which after being washed with 
water are dissolved in alcohol. The alcoholic solution on evaporation gives crystals 
of alizarine, which may be purified by recrystallization. The compound of verantine 
with oxide of copper is decomposed with muriatic acid. The liquid filtered from the 
alumina compound of alizarine and verantine is evaporated to dryness, muriatic acid 
is added to the residue, which is placed on a filter and washed with cold water until 
all the acid and salts of alumina are removed. On being now treated with boiling 
water, a quantity of dark brown resinous drops sink to the bottom of the vessel and 
cohere into a semi-fused mass, while brownish-yellow flocks float in the water. Tlie 
water is decanted from the mass at the bottom, carrying with it the flocks. This pro- 
cess is repeated with fresh quantities of water until no more flocks are carried away 
by it. The resinous mass at the bottom now consists principally of rubiretine. It 
may be purified by dissolving in cold alcohol, which leaves behind a quantity of 
verantine. The brownish-yellow flocks consist chiefly of verantine and rubianine ; 
they are treated with boiling water, in which the rubianine dissolves, and from which 
it is again deposited, on filtering the water boiling hot and allowing to cool, in orange- 
coloured flocks. The process is repeated until the water dissolves nothing more. The 
orange-coloured flocks of rubianine are collected on a filter and dissolved in boiling 
alchohol, out of which the rubianine crystallizes on cooling in yellow needles. The 
mother-liquor is somewhat darker than a mere solution of rubianine would be. It 
contains a little alizarine and rubiretine, which maybe separated by means of acetate 
of alumina, as before described. The verantine which is left behind by the boiling 
water is mixed with the other portions obtained from the lead and copper compounds, 
and the whole is dissolved in a small quantity of boiling alcohol, out of which the 
verantine is deposited on cooling as a dark reddish-brown or yellowish-brown pow- 
der, which may be purified by a second solution in alcohol. 
These substances can, as may be supposed, be obtained without any difference in 
properties by adding sulphuric or muriatic acid to an extract of madder made with 
