MR. SCHUNCK ON RUBIAN AND ITS PRODUCTS OF DECOMPOSITION. 
85 
These numbers correspond with the formula C 32 Hg O 17 , as will be seen by the 
following calculation : — 
Eqs. 
Carbon .... 32 
Hydrogen ... 9 
Oxygen . . . . 17 
Calculated. 
Found. 
192 
56*97 
57-25 
9 
2-67 
2-91 
136 
40*36 
39-84 
337 
100-00 
100-00 
This composition differs, as will be seen, very little from that found in my former 
experiments. 
Some fresh rubiacic acid made in the same manner as that of the last analysis, was 
dissolved in carbonate of potash, the solution was evaporated to crystallization, the 
crystallized potash salt was again dissolved in boiling water, and nitrate of silver was 
added to the solution. The precipitate was now no longer red, but of a dull orange 
colour. 
OT 700 grin, of this precipitate gave 0-2720 carbonic acid and 0'0370 water. 
In 100 parts — 
Carbon 43-63 
Hydrogen 2-40 
The formula Cs^HgOis+AgO requires in 100 parts— 
Carbon 43-24 
Hydrogen T80 
If the formula of the potash salt be similar to that of the silver salt, viz. C 32 HgOig 
4 -KO, it must contain in 100 parts — 
Carbon 51-17 
Hydrogen 2-13 
Oxygen 34*12 
Potash 12-58 
In my former experiments I obtained as an average of three determinations — 
Carbon 51-37 
Hydrogen 2*41 
Oxygen 33*18 
Potash 13*04 
It appears therefore that the four first analyses given above were made with impure 
acid. The analysis No. I. corresponded, as I have shown, with the formula Cgi H 20 Og-. 
Now if from this formula be deducted that of the pure acid C 32 Hg O 17 , the difference 
will be C 32 Hii Ojo, which is the formula given above for rubiacine. It is therefore 
almost certain that it was an admixture of the latter substance with the acid which 
raised the amount of carbon and hydrogen in the four first analyses. Whether this 
impure acid is to be considered as a chemical compound of acid and rubiacine, or 
whether it contains them in a state of mechanical mixture, is a point not easily deter- 
MDCCCLIII. N 
