26 EXPERIMENTS ON THE COLORIFIC PROPERTIES OF LICHENS. 
competent chemists and lichenologists. Not only are new fields 
of research open, but the need of a revision of all previous analyses 
is even more evident. Chemists themselves are forced to make 
this admission ;* * * § but the subject of the Chemistry of the Lichens 
has not as yet proved a sufficient counter-attraction to the innu- 
merable other interesting problems that are daily being exposed for 
solution in the wide domain of organic chemistry. Meanwhile, the 
crude researches of lichenologists may serve to pave the way for 
the subsequent more scientific and precise analyses of chemists, 
by indicating the directions in which chemical inquiry is likely to 
prove useful or successful. Quite recently, moreover, a strong 
opinion as to the utility of researches on the Lichen colouring 
matters — of the character of those formerly published by myself — • 
has been expressed by the highest living authority on the subject 
of general Lichenology, viz., Yon Kempelhuber, of Munich ;f 
while, in the long interval that has elapsed since the publication of 
my first series of researches, no other experimentalist has occupied 
the same wide field. 
The foregoing along with other considerations induce me to 
submit the results of another more systematic and complete series 
of experiments, supplementary to those presented in 1853-4-5. 
These results include, or consist of, a general inquiry into colour- 
development or colorific property in the whole family of Lichens. 
The experiments in question are on the one hand a repetition, and 
on the other an extension, of my former series of experiments, J and 
illustrate generally the colour-reactions of Lichens. The results 
given are mainly those which are positive ; they represent only a 
proportion of several hundred experiments, the majority of which 
led to no colour-reaction at all. In the present series of experi- 
ments I used a solution of the Lichen colorific principles or colouring 
matters in hot water or alcohol — boiling the Lichens, previously 
reduced to powder or minute fragments. My reason was that the 
majority, at least, of the said colorific or colouring principles or 
matters, while insoluble in cold and sparingly so in hot water, are 
readily soluble in cold or boiling alcohol. § The reactions 
developed are thus the effects of re-agents on the alcoholic or aqueous 
decoctions of the Lichen-thallus. 
In order to secure something like uniformity, if not precision, in 
the nomenclature oj the colours obtained, I carefully compared them 
with the colour- specimens published in the little work of Syme (in 
* Thus Professor Crum-Brown, of Edinburgh, to whom I proposed a 
joint new experimental inquiry, wrote me in Jany., 1807, “ There is still 
. . . room for much further work.” 
f “ Geschichte und Litteratur der Lichenologie ” (1867), p. 423-4. 
j “ Phytologist,” vol. iv. (1853), p. 1068. 
§ This fact, the result of chemical research, is sufficient of itself to throw 
doubt on the possibility of properly educing colour-reaction by the mere ap- 
plication to the Lichen-thallus, or apothecium, of a drop of bleaching solution 
or liquor potassse ! Vide paper on “ Chemical Reaction as a Specific 
Character” ( ob.citj . 
