286 DR. KANE ON THE CHEMICAL HISTORY OF ARCHIL AND LITMUS. 
the alcohol had not taken up. There then dissolves a substance which colours the 
water golden yellow, and there remains a dark red substance, apparently insoluble in 
water. The yellow colour imparted to the water cannot be due to any minute por- 
tion of this substance, for when the yellow liquor is evaporated, it leaves a film of 
solid material, which is not red, as should be the case, but yellow. The yellow 
substance is therefore probably a peculiar material, most likely the yellow material 
(gelbe materie) of Heeren, but from the minute traces of it which I could obtain, I 
could not make any additions to its history further than that the alkalies did not 
appear to alter its colour. The substance insoluble in water has still to be separated 
from a quantity of vegetable fibre, arising from half decomposed shreds of lichen, and 
from some earthy matters with which it is mixed. For this purpose it is to be boiled 
with a weak solution of caustic potash, in which it rapidly dissolves. The solution 
is wine-red coloured, without a shade of purple. On neutralizing the solution by an 
acid, there does not take place any precipitation ; but if the solution be then evapo- 
rated to dryness, and then washed until all the salt of potash is removed, the substance 
remains pure, as far as the experiments I have instituted with it could indicate. To 
this substance, from considerations which will hereafter appear, I give the name of 
Azoerythrine. 
The archil of commerce is thus found to consist essentially of three ingredients, 
orceine, erythroleic acid, and azoerythrine ; of each of the two former there exist two 
modifications, which will shortly be described ; and there is in addition, the yellow 
matter. It is important to determine now, how far these results agree with those 
obtained by Heeren, in examining the products evolved by his erythrine in contact 
with air and with ammonia. 
1st. In all properties given by Heeren, his lichen-red (flechtenroth) identifies 
itself with orceine. 
2nd. The azoerythrine assimilates itself to the wine-red pigment of Heeren, in 
the characteristic property of not being coloured violet by alkalies. He appears, 
however, to consider the wine-red pigment as being soluble in water, whilst in reality 
it is its combination with an alkali that is so. As he operated on a solution in am- 
monia, there is every reason to look upon the substances as identical. 
3rd. The yellow substance is mentioned by Heeren only incidentally, and no com- 
parison can be instituted. 
4th. Heeren did not meet with the erythroleic acid ; indeed, operating on ery- 
thrine, he could not meet with it, as it shall be hereafter shown to have its origin m 
a substance of a totally different nature. 
The researches of Heeren, having thus to a great extent anticipated my results as 
to the constitution of archil, it may be necessary for me briefly to justify the change 
that I have made in his nomenclature. The word lichen-red would be certainly a 
much better name for that substance than orceine, since orcine is not the only pri- 
mitive material capable of yielding it ; but the word Orceine has become by the 
