324 DR. KANE ON THE CHEMICAL HISTORY OF ARCHIL AND LITMUS. 
Pb O Cl . Ba 0 2 and Ba O . Cl ; so from orceine, the bodies chlororceine and azolit- 
mine may be formed of similar constitution. 
I have already pointed out my reasons for considering these different series of co- 
loured bodies as consisting not of the same organic radicals, combined with different 
quantities of oxygen, but as being, though formed in succession by gradual oxidation, 
when once produced, independent of each other, and not reducible to any common 
type. I should wish to be understood, however, as not insisting positively upon any 
theoretical considerations regarding the internal constitution of these bodies ; I have 
met with too many difficulties in their investigation, and have seen too often ideas 
which I had thought well established by one series of analyses overturned by those 
subsequently made, not to be fully sensible of the liability to correction, to which 
even my present opinions may be subject. Among substances, so numerous, so simi- 
lar in properties, and so variable in constitution ; in a field of investigation which for 
numerical or accurate purposes must be looked upon as previously unexplored, it 
would be inexcusable rashness and presumption in me, not to look forward to the 
correction of my results in many instances, by those chemists who may hereafter de- 
vote themselves to the study of this subject, or to consider these researches as being 
more than introductory to the more accurate and detailed examination, which the 
great fertility and importance of this department of chemistry deserves, and, I trust, 
is likely to obtain from more distinguished chemists. 
Royal Dublin Society , 
April 21 st, 1840 . 
