406 MR. SCHUNCK ON RUBIAN AND ITS PRODUCTS OF DECOMPOSITION. 
constituents. If the oxide of lead be deducteci, then the rubihydran combined with 
it will have the following composition in 
100 parts : — 
I. 
II. 
Carbon 
. 51’37 
51-38 
Hydrogen . . , . 
6’12 
5-92 
Oxygen 
. 42-51 
42-70 
100-00 
100-00 
It will be seen that this is exactly the composition of the substance itself according 
to the analysis given above, and it follows that the composition of rubihydran, both 
in a perfectly dry state and when in combination with oxide of lead, is expressed by 
the formula C 55 H 39 O 35 . It differs therefore from rubian by containing the elements 
of 5 equivalents more of water. That it should yield the same products of decom- 
position as rubian and rubidehydran is therefore not at all extraordinary. 
The rubiadine which is formed by the decomposition of rubihydran with acids may 
be obtained in a state of greater purity and with much greater facility from this, than 
from any other souree. It is separated from the other products of decomposition in 
the manner I have described when treating of the action of alkalies on rubian. 
It is purified by dissolving it in boiling alcohol and adding to the boiling solution 
hydrated oxide of lead, when it crystallizes from the filtered solution in beautiful 
golden-yellow, glittering scales, some of which assume the form of regular four-sided 
tables, possessing all the properties of rubiadine*, but evidently freer from impurities 
than when obtained by the action of alkalies on rubian. 
I. 0'3060grm. of this substance, dried at 100° C., gave 0'7795 carbonic acid and 
O’] 380 water. 
II. 0’2580 grm. of the same, recrystallized from boiling alcohol, gave 0’6600 
carbonic acid and O’ 11 90 water. 
From these numbers it may be inferred that its composition is as follows: — 
Carbon . . 
. . 32 
192 
Calculated. 
69’31 
I. 
69-47 
II. 
69’76 
Hydrogen . 
. . 13 
13 
4-69 
5*01 
5-12 
Oxygen . . 
. . 9 
72 
26-00 
25-52 
25-12 
277 
100-00 
100-00 
100-00 
The formula C 32 Hjg O 9 , to which these analyses lead, dilFers from the one formerly 
given, C 32 H 12 O 8 , by 1 equivalent of water. I prefer the former, since the substance 
employed in the last analyses was evidently purer than that used in any previous one. 
It will be seen also, that the formula just given is confirmed by an examination of 
the products of decomposition of rubian with chlorine. 
* In examining these crystals I discovered a property of rubiadine which I had not previously observed. If 
the ammoniacal solution, which is red, be mixed with chloride of barium, it deposits a quantity of dark brownish- 
red needle-shaped crystals, which are evidently the baryta compound of rubiadine, while the liquid loses almost 
all its colour. The rubiadine derived directly from rubian also yields these crystals. 
