72 MR. SCHUNCK ON RUBIAN AND ITS PRODUCTS OF DECOMPOSITION. 
The ulmic acid of Mulder, obtained by the action of muriatic acid on cane-sugar, 
contains, according to that chemist (C=6T1), — 
Carbon 68’95 
Hydrogen 4‘23 
Oxygen 26*82 
The formula given by Mulder for ulmic acid, viz. C40 H14 O12, requires in 100 parts 
Carbon 68*57 
Hydrogen 4*00 
Oxygen 27*43 
The identity in composition and properties of this acid, and the substance formed 
by the action of alkalies on rubian, leave no doubt of their being the same. 
Rubladine . — This substance, which has not hitherto been observed among the 
products derived from madder, bears a close resemblance in its appearance and many 
of its properties to rubianine, the place of which it in fact occupies in the series of 
substances produced by the action of alkalies on rubian. Besides its composition, 
however, there are several properties belonging to it so characteristic, that it cannot 
be confounded with rubianine or any of the substances previously described. When 
crystallized from alcohol, it is obtained in the shape of small yellow or orange-coloured 
needles. A very minute degree of impurity, however, seems to prevent its assuming 
a crystalline form, in which case it is obtained in small granular masses, or as a yellow 
amorphous powder. It may be purified by dissolving it in a small quantity of boil- 
ing alcohol, and adding to the boiling solution either hydrated oxide of lead, or prot- 
oxide of tin. On filtering boiling hot and allowing to cool, it crystallizes out. 
When heated on platinum foil, it melts and burns with flame. When cautiously 
heated between two watch-glasses, it may be almost entirely volatilized. On the 
lower glass a very slight carbonaceous residue is left, while the upper glass is covered 
with a quantity of partly yellow, partly orange-coloured micaceous scales, endowed 
with considerable lustre. These scales possess all the properties of rubiadine itself. 
Rubiadine is insoluble in water. It communicates hardly any colour to boiling 
water, and the filtered liquid deposits nothing on cooling. It is more soluble in 
alcohol than rubianine. It dissolves in concentrated sulphuric acid with a dark 
yellow colour, and is reprecipitated by water in yellow flocks. If the solution in 
sulphuric acid be boiled, the colour changes to a dark yellowish-brown, a little sul- 
phurous acid is disengaged, and the addition of water now causes a yellowish-brown 
precipitate. On treating rubiadine with boiling nitric acid, it dissolves, nitrous acid 
is disengaged, and the liquid on cooling deposits nothing, so that the substance seems 
to be decomposed by the acid. Towards alkalies rubiadine behaves in a similar 
manner to rubianine. Ammonia and carbonate of soda change its colour very little 
in the cold. It is only on boiling the alkaline liquids that it dissolves with a blood- 
