276 DR. KANE ON THE CHEMICAL HISTORY OF ARCHIL AND LITMUS. 
The mass insoluble in water is next to be acted on by a weak solution of caustic 
potash at a temperature of about 100° of Fahr. until it ceases to dissolve. In genera! 
but a very small quantity of material remains behind. The alkaline liquor having- 
been carefully filtered, is then to be rendered slightly acid by muriatic acid, a copious 
greenish yellow precipitate is produced, which must be collected and washed to remove 
all trace of acid. This substance is then to be dissolved in weak water of ammonia, 
and mixed with a solution of chloride of calcium in water ; any precipitate which forms 
is to be separated by the filter, and the clear yellowish green liquors again treated 
by muriatic acid, by which the substance is precipitated, and having been freed from 
adhering traces of acid by careful washing, it may be considered pure. To this body, 
as being the origin of the coloured series, I have given the name of Erytkryline. 
The precipitate produced as above described with chloride of calcium, and which 
is generally formed but in exceedingly small quantity, is to be treated with dilute 
muriatic acid, which separates a white substance, identical, so far as the small quan- 
tity of it at my disposal allowed me to determine, with the roccellic acid discovered 
by Heeren and analysed by Liebig, but as its acid characters are not marked, I 
would propose for it the more appropriate name of Roccelline. 
The watery solutions which had been obtained in the treatment of erythryline de- 
posit, on cooling, beautiful crystals, having the appearance of boracic acid. The 
quantity of these crystals obtained depends on the manner in which the mass has 
been treated: if the boiling and filtration had been expeditiously carried on, the 
liquor often solidifies from the quantity of crystals which separate on cooling, but if 
the process had been slowly carried on, very little is obtained. These crystals having 
been removed, no more can be obtained by evaporating the liquors in which they 
had been formed, and if a liquor containing crystals be heated so that they redissolve, 
but very few again appear on the liquor being allowed to cool. This crystallized body, 
on examination, is found to be identical with the pseudo-erythrine discovered by 
Heeren and analysed by Liebig ; but as it will be hereafter shown that this body is 
not the accidental product which Heeren considered it to be, but in reality one of 
the most important in the series, and that there is very great reason for supposing 
the erythrine of Heeren to have been a mixture of other bodies, I believe that I am 
justified in transferring to this body the name erythrine, as certainly the word pseudo 
was attached to it by Heeren under a misconception. 
The watery solution, from which the crystallized erythrine has been deposited, is 
always more or less brown coloured. When evaporated in a water bath, it gives a 
semifluid brownish mass, which can scarcely be rendered quite solid by any tempe- 
rature below that of incipient decomposition. The circumstance of this substance 
being formed from erythrine, its great solubility in water, and its peculiar bitterish 
taste, show it to be the erythrine-bitter of Heeren. This name, being well enough 
suited to our language, I shall retain. 
When a strong solution of erythrine-bitter is exposed to the action of the air for 
