MR. SCHUNCK ON RUBIAN AND ITS PRODUCTS OF DECOMPOSITION. 77 
decomposition of the alumina precipitate, and the mixture is dissolved in boiling- 
alcohol. To the alcoholic solution is added acetate of copper, which gives a dirty 
purple precipitate, consisting of verantine, rubiafine and a portion of the alizarine in 
combination with oxide of copper, while the liquid, which has a fine purple colour, 
contains the greatest part of the alizarine. The latter is obtained from this liquid by 
precijhtating with muriatic acid and water, and purified by crystallization. The 
precipitate produced by acetate of copper is decomposed with muriatic acid, which 
leaves undissolved a quantity of red flocks. These, after filtration and washing with 
water, are dissolved in boiling alcohol. Into the boiling solution is introduced a 
quantity of hydrated protoxide of tin, which thereby acquires a light brown colour, 
while the liquid becomes light yellow, and on being filtered boiling hot and allowed 
to cool, deposits the rubiafine in yellow shining plates and needles, which are purified 
by recrystallization from alcohol. The oxide of tin-lake left on the filter is treated 
with cold muriatic acid, which dissolves the greatest part of the oxide of tin, and 
leaves undissolved a dark reddish-brown powder. This is placed on a filter, washed 
first with muriatic acid, then with water, and then treated with boiling alcohol. The 
alcohol leaves a great part of it undissolved, and on being filtered boiling hot deposits 
on cooling a brown powder consisting of verantine. The liquid on evaporation gives 
a quantity of alizarine, mixed with verantine. The substance left undissolved by the 
boiling alcohol is dark brown. It is a compound of verantine and oxide of tin, from 
which I have not been able to extract the oxide of tin by acids or any other means. 
It is soluble in ammonia and carbonate of soda, and is precipitated unchanged by 
acids. 
The same products as those just mentioned may be obtained from madder by 
extracting it with cold or tepid water, allowing the extract to stand until a coagulum 
has been formed in it, placing the coagulum on a calico strainer and then treating it 
with boiling alcohol. The alcohol leaves undissolved a quantity of ferment, and is 
found to contain the same substances as those originating from the direct action of 
the ferment on rubian. 
The liquid filtered from the gelatinous mixture of substances insoluble in water, 
formed by the action of the ferment, still contains in solution a considerable quantity 
of sugar. On adding to it a small quantity of caustic baryta, a pinkish-white preci- 
pitate falls, consisting probably of pectic acid in combination with baryta. The 
liquid being filtered, the baryta is precipitated with sulphuric acid, the excess of the 
latter is removed with carbonate of lead, and a small quantity of lead which dissolves 
is thrown down with sulphuretted hydrogen. The liquid now leaves, on evaporation 
at the ordinary temperature over sulphuric acid, a brownish-yellow syrup, having 
the same appearance and properties as the sugar produced by the action of acids on 
rubian. 
The following analyses prove the identity of the alizarine formed by the fermenta- 
tion of rubian with that derived from other sources: — 
MDCCCLIII. 
M 
