MR. SCHUNCK ON RUBIAN AND ITS PRODUCTS OF DECOMPOSITION. 71 
Hence may be deduced the following composition : — 
Carbon . . 
Eqs. 
. . 12 
72 
Calculated. 
30*17 
I. 
29*41 
II. 
30*01 
Hydrogen . 
. . 10 
10 
4*19 
4*68 
4*62 
Oxygen . . 
. . 10 
80 
33*54 
33*49 
Baryta . . 
. . 1 
76*6 
32*10 
31*88 
238*6 
100*00 
100*00 
This compound, it will be seen, is identical in composition with the baryta com- 
pound of cane sugar. If the formulae of the two compounds be compared together, 
it is evident that if both be correct, the one containing most baryta must be written 
thus, — Ci 2 Hio Oio-f BaO-l-BaO HO. In this case, however, it would be difficult to 
conceive how it is possible for the second atom of baryta to escape the action of the 
carbonic acid used in its preparation. It is therefore more probable that the true 
formula is C 12 Hm Oio+ 2 BaO, which requires in 100 parts — 
Carbon 22*84 
Hydrogen 3*17 
Oxygen 25*39 
Baryta 48*60 
In fact the amount of carbon and hydrogen found by experiment agree better with 
these numbers than with those of the other formula. 
These analyses lead to the conclusion, that the sugar formed by the decomposition 
of rubian contains 12 , not 14 atoms of carbon. Nevertheless it is doubtful whether 
in these baryta compounds the sugar exists in the same state as it does when formed 
by the action of acids on rubian. In the latter state it seems incapable of entering 
into combination with bases such as baryta or oxide of lead. It is therefore pro- 
bable that by the continued action on it of alkalies or alkaline earths it undergoes 
some change, possibly in consequence of the loss of the elements of water. 
Among the products of the action of alkalies on rubian, I have mentioned a dark 
brown substance insoluble in boiling alcohol. This substance is soluble in alkalies 
with a brown colour, and is reprecipitated by acids. It resembles in all respects the 
black substances bearing the general name of humus, which are formed by the action 
of strong acids and alkalies on ordinary sugar. It was analysed with the following 
result : — 
0*3215 grm. gave 0*8040 carbonic acid and 0*1260 water. 
In 100 parts therefore it contains — 
Carbon 68*20 
Hydrogen 4*35 
Oxygen 27*45 
