294 DR. KANE ON THE CHEMICAL HISTORY OF ARCHIL AND LITMUS. 
ence here to have arisen from admixture of a still more basic salt, produced by the 
presence of a slight excess of ammonia in the solution of orceine. Indeed, by boiling 
the solution of orceine in ammonia, the excess of ammonia cannot be completely 
driven off, so as to leave any kind of neutral compound ; and to form salts of definite 
constitution I found it indispensable to add small quantities of acid to the mixed 
liquors, so as to leave the supernatant liquor exactly neutral. If the acid be in excess 
the precipitate becomes contaminated by some orceine which separates along with it. 
The washing of these salts of orceine must be continued until the filtered liquors be- 
come tinged crimson, owing to a certain quantity of the orceine salt itself being dis- 
solved, which does not happen until the removal of the foreign saline matter has been 
nearly perfect. 
In order to ascertain the constitution of the violet compound of ammonia and of 
orceine, 0273 of betaorceine was kept in a current of dry ammonia as long as any 
increase of weight took place. The combination was accompanied with the evolution 
of heat, and the violet-coloured substance which resulted was found to weigh 0295 
gramme. On exposure to a temperature of 212° in a current of air, the ammonia was 
after some time totally removed, and the betaorceine remained unaltered. This pro- 
portion of ammonia corresponds to 8’06, absorbed by 100 of betaorceine, very closely 
approximating to 8'58, which theory gives equivalent to an atom. The violet com- 
pound is therefore to be considered as C 18 H 10 N 0 8 + N H 3 ; and I have found that the 
betaorceine when dried at 150° Fahr. retains an equivalent of water, which it loses at 
212°, and that consequently the bodies C 18 H 10 N O g + Ad H and C 18 H 10 N 0 8 -f OH 
are equivalent to one another. This hydrate of betaorceine is of a much lighter co- 
lour than the anhydrous compound, and it will be hereafter shown that a correspond- 
ing body, C 18 H 10 N 0 8 + S H, is capable of being formed. 
The most important question in the philosophical history of these bodies, that of 
their origin, requires now to be discussed, and as there is but little doubt that the 
betaorceine, C 18 H 10 N 0 8 , is formed by the gradual oxidation of the alphaorceine, 
C 18 H 10 N 0 5 , our views need only involve the production of the latter compound. In 
the case of archil prepared from the Variolaria dealbata , where the primitive substance 
is orcine, the production of orceine is easily understood ; the dry orcine having the 
constitution C 18 H 7 0 3 , it requires only the combination of an atom of ammonia and 
the absorption of two or five equivalents of oxygen to form the one or the other 
variety of orceine. But in the case of ordinary archil, where the Parmelia or the 
Roccella had been used, the transition from the erythrine series to that of orceine 
becomes much more complex, as not only a certain quantity of hydrogen, but also 
four equivalents of carbon must be removed ; the substances of the former group 
containing twenty-two atoms of that element, while those of the latter include only 
eighteen. 
The azoerythrine is probably the substance which forms the transition between the 
two groups, and from it the origin of alphaorceine can easily be explained. 
