MR. SCHUNCK ON RUBIAN AND ITS PRODUCTS OF DECOMPOSITION. 
455 
which on further heating disappears entirely. When heated in a glass tube it gives a 
small quantity of a yellow crystalline sublimate, but not by far so large a quantity as 
is obtained under the same eircumstances from rubiacine, which, when carefully 
heated, may be almost entirely volatilized. It is soluble in concentrated sulphuric 
acid with a yellow colour ; the solution on boiling becomes blaek and gives off sul- 
phurous acid. A solution of rubiacine in concentrated sulphuric acid, remains quite 
unchanged on boiling. It is not affected either by dilute or concentrated nitric acid, 
even on boiling ; it merely dissolves in them, and crystallizes out again on the acid 
cooling, just as from boiling water. When treated in the cold with a solution of car- 
bonate of potash or soda, or liquid ammonia, it does not dissolve, nor is its colour at 
all changed. When the liquid is boiled, it dissolves however with a blood-red colour. 
Nevertheless it cannot be said to combine with the alkali, but merely to be dissolved 
by it ; for on allowing these solutions to stand for some time, a yellow crystalline mass 
again separates, which is nothing but the substance itself. The ammoniacal solution 
gives red precipitates with the chlorides of barium and calcium. The alcoholic solution 
gives no precipitate with sugar of lead, whereas a solution of rubiacine gives a dark 
red precipitate with sugar of lead. It dissolves in a concentrated solution of per- 
chloride of iron with a dark brown colour, but is not thereby converted into rubiacic 
acid. It communicates to mordanted cloth only a slight tinge of colour, similar to 
that produced by rubiacine. 
Its analysis gave the following results : — 
I. 0‘3520 grm. substance, dried at 100° C. and burnt with chromate of lead, gave 
0’7400 carbonic acid and 0T750 water. 
II. 0*3805 grm. of the same preparation gave 0*7990 carbonic acid and 0*1890 
water. 
III. 0*3965 grm. of another preparation gave 0*8330 carbonic acid and 0*1890 
water. 
IV. 0*2480 grm. of the same preparation as the last, recrystallized from alcohol, 
gave 0*5290 carbonic acid and 0*1280 water. 
V. 0*3735 grm. of a third preparation gave 0*7925 carbonic acid and 0*1785 
water. 
VI. 0*3995 grm. of the same preparation gave 0*8450 carbonic acid and 0*1855 
water. 
These numbers 
correspond in 
100 parts 
to — 
I. 
II. 
III. 
IV. 
V. 
VI. 
Carbon . . 
. . 57*33 
57'26 
57*29 
58*17 
57*86 
57*68 
Hydrogen . 
. . 5*52 
5*51 
5*29 
5*73 
5*31 
5*15 
Oxygen . . 
. . 37*15 
37*23 
37*42 
36*10 
36*83 
37*17 
I have as yet been unsuceessful in my attempts to determine the atomic weight of 
rubianine. The little affinity which it has for bases is proved by the fact above men- 
3 N 2 
