DR. KANE ON THE CHEMICAL HISTORY OF ARCHIL AND LITMUS. 303 
The erythrolitmine-ammonia being insoluble, the compounds of erythrolitmine 
with metallic oxides cannot be formed by the method of double decomposition used 
in so many other cases. The mode I found most convenient, was to boil the erythro- 
litmine with some alcohol, so as to have it partly dissolved and partly diffused in 
minute division through the liquor, and then to add it to a solution of basic acetate 
of lead. A deep purple precipitate forms, which is to be boiled for a few minutes, 
then well washed and filtered. Having been dried at 212° in Liebig’s apparatus, it 
was analysed. 
0532 gramme gave 0*606 of carbonic acid, and 0*229 of water. 
0*583 gave 0*146 of oxide of lead, and 0*105 of metallic lead. 
The composition resulting from these numbers indicates the formula C 26 IT 22 0 12 
-f- 2 Pb O, which gives 
26 Carbon . . 
Theory. 
158*6 31*73 
Experiment. 
31*52 
22 Hydrogen . 
22*0 
4*40 
4*78 
12 Oxygen . . 
96*0 
19*21 
19*27 
Oxide of lead 
223*2 
44*66 
44*43 
499*8 
100*00 
100*00 
The twenty-third equivalent of hydrogen is here eliminated and replaced by 
oxide of lead, the true formula of the erythrolitmine is therefore C 26 H 22 0 12 . 
It is evident that this substance belongs to the same series of bodies as the ery- 
throlein and the erythroleic acid, the relation of the carbon and hydrogen being 
the same, the oxygen, however, having increased to twelve equivalents. That this 
body is a direct product of the oxidation of erythroleic acid, is completely shown by 
the fact, that if semifluid erythroleic acid be left exposed to the air for some weeks, 
it gradually solidifies ; it is then insoluble in ether, is coloured blue by ammonia, 
and is, in fact, found to have been changed into erythrolitmine. The bodies are 
therefore related to each other as the two orceines. 
The origin of erythrolein is a point on which, however, I do not at all feel perfectly 
decided. It will be recollected how beautifully simple the production of erythroleic 
acid from roccelline appeared to be, two equivalents of hydrogen being replaced by 
two of oxygen. The production of erythrolein does not appear to me by any means so 
easily explained. The relation between roccelline and erythrolein is extremely simple. 
Roccelline. Erythrolein. 
^26 ^24 ^6 = ^26 ^22 ^4 + 2 H O. 
And if we looked no further, it might easily be said that by a metameric change the 
roccelline, in decomposing, yielded erythrolein and water, and that afterwards the 
absorption of oxygen gave from 
Erythrolein = C 26 H 22 0 4 , 
Erythroleic acid = C 26 H 22 O s and 
Erythrolitmine = C 26 H 22 0 12 , 
a chain of reactions among the simplest possible. 
