106 MR. SCHUNCK ON RUBIAN AND ITS PRODUCTS OF DECOMPOSITION. 
A quantity of material similar to the last, obtained on a different occasion, was 
treated in the same way with boiling alum liquor, and the deposit formed on the 
liquor cooling was submitted to analysis. It had a much lighter colour than the 
preceding, and when dissolved in alcohol, the latter left on evaporation crystals, 
apparently of alizarine, mingled with red crystalline masses resembling impure 
alizarine. 
0'4000 grm. gave 0'9870 carbonic acid and 0‘1390 water. 
0‘3840 grm. left on being incinerated 0‘0060 aluraina=l’56 per cent. 
After making the necessary correction for the alumina, these numbers correspond 
in 100 parts to — 
Carbon 68'36 
Hydrogen 3’92 
Oxygen 27’72 
The formula C.eH,.0„=3C,.H,0.+C„H.0, requires in 100 parts— 
Carbon 68 29 
Hydrogen 4‘06 
Oxygen 27'65 
These two specimens therefore of a substance prepared in the same way, both of 
which would, according to the definition of Wolff and Strecker, pass for purpurme, 
possessed a composition, which in the one case corresponded to a mixture of 1 equiv 
of alizarine and 3 equivs. of verantine, in the other case to a mixture of 3 equivs. o 
alizarine and 1 equiv. of verantine. A still more manifest proof of the fact of purpurme 
not being a substance of uniform composition, is derived from an examination of the 
liquid from which these specimens were deposited. To the bright red liquid from 
which the last was deposited, I added after filtration muriatic acid and boiled. A 
yellow precipitate was produced, which was collected on a filter and washed. A small 
quantity of it being dissolved in alcohol, the alcohol left on evaporation crystals of 
apparently pure alizarine. Its analysis also showed that it consisted of alizarine 
almost in a state of purity. 
0'2390 grm. gave 0*6040 carbonic acid and 0*0980 water. 
In 100 parts it contained therefore — 
Alizarine. 
Carbon .... 68*92 69*42 
Hydrogen . . . 4*55 4*13 
Oxygen .... 26*53 26*45 
I now prepared some so-called purpurine from garancine. The garancine was 
treated with boiling alum liquor, and the liquor was strained boiling hot through 
calico. On cooling there was formed a copious deposit, which was redissolved in 
fresh alum liquor. The deposit formed this time, which was very trifling, was 
