MR. SCHUNCK ON RUBIAN AND ITS PRODUCTS OF DECOMPOSITION. 397 
corresponding to the formula C 52 H 29 O 27 , as the following calculation shows : — 
Carbon 
Eqs. 
... 52 
312 
Calculated. 
56*01 
Hydrogen 
... 29 
29 
5*20 
Oxygen . 
... 27 
216 
38*79 
557 
100*00 
Rubianate of potash was prepared by dissolving the acid in as small a quantity 
of water as possible, adding an excess of carbonate of potash, allowing the salt to 
crystallize, collecting it on a filter, washing it with just sufficient water to remove the 
excess of alkali, and drying. On analysing it I obtained the following results : — 
I. 0‘3580grm., dried in the water-bath and burnt with chromate of lead, gave 
0*6830 carbonic acid and 0*1590 water. 
0*5590 grm. gave 0*0780 sulphate of potash. 
II. 0*4850 grm. of another preparation, dried in vacuo, gave 0*9250 carbonic acid 
and 0*2070 water. 
0*8140 grm. gave 0*1150 sulphate of potash. 
These numbers lead to the following composition : — 
Carbon 
Eqs. 
. . 52 
312 
Calculated. 
52*42 
I. 
52*03 
11. 
52*01 
Hydrogen 
. . 28 
28 
4*70 
4*93 
4*74 
Oxygen 
. . 26 
208 
34*97 
35*50 
35-62 
Potash . . 
. . 1 
47-2 
7-91 
7*54 
7*63 
595*2 
100*00 
100*00 
100*00 
The soda salt, prepared in the same way as the potash salt, was also analysed, but 
the analysis led to no satisfactory results. 
A compound with baryta was obtained by dissolving the acid in water and adding 
ammonia and chloride of barium. The precipitate, which was bulky and of a fine 
crimson colour, was placed on a filter and washed with water. During the washing 
its bulk diminished and the colour changed to red, probably in consequence of its 
losing part of its baryta. Analysis showed it to be a basic compound, in which the 
acid is to the base as 2 : 3. The neutral baryta salt was obtained by adding chloride 
of barium to a watery solution of rubianate of potash, when a red precipitate fell, 
which was collected on a filter, washed with water, and dried in vacuo, 
I. 0*6020 grm. of the latter compound, burnt with chromate of lead, gave 1*0800 
carbonic acid and 0*2580 water. 
0*5180 grm. gave 0*0925 sulphate of baryta. 
II. 0*4440 grm. gave 0*7870 carbonic acid and 0*1900 water. 
0*4890 grm. gave 0 0870 sulphate of baryta. 
These numbers lead to the formula C 52 H 28 Oge+BaO+HO, as the following com- 
parison of the experimental results with the theoretical composition shows : — 
