NOTE ON A CRITICAL CHINESE GRASS, 109 
rous sources of supply, and media or centres of export and import. 
Dr. Stenhouse writes me, * You are probably aware that the coal-tar 
colours have greatly diminished the value of Lichens as dyeing sub- 
stances;" and there seems a prevalent impression among chemists and 
manufaeturers that the deterioration in market value to which I have 
referred is attributable solely to the disadvantageous competition of 
Orchill with aniline. To me it appears much more clear that there has 
been an increased demand for, and an. increased supply of, ** Orchella 
weeds," and the usual sequel of reduction of price,—with the progress 
of commercial tinctorial enterprise. 
Dr. Stenhouse long ago recommended that the importation of the 
somewhat bulky Dye-lichens themselves should be superseded by that 
of their colorific principles or acids only ; and Professor Hofmann, in 
his report already alluded to, speaks of the new mode of extracting 
these colorifie principles as one of the most important improvements 
in this branch of manufacture. He refers especially to the economy 
and facility of manipulating a comparatively small bulk of material 
during the most important stage of manufacture. The plans and pro- 
cesses thus suggested and recommended do not, however, as yet appear 
to have been adopted by manufacturers or importers, or to have been 
even tried at all upon the large scale so far as I am aware—a circum- 
stance which may be due to the striking difference or discrepancy 
already indicated between operations on the large and small scale, and 
the impossibility of founding upon the latter inferences or rules for 
guidance in the former. This conservative inaction, however, shows, I 
think, that in this country, at least, the manufacture of Lichen-dyes 
has not reached perfection ; and that if, with all its imperfections of 
manufacture, Orchill can successfully compete with aniline, whose pre- 
paration and applications are much more highly scientific, it has little 
reason to fear competition in the future when applied chemistry lends 
its important aid to its proper production. - 
NOTE ON A CRITICAL CHINESE GRASS. 
By H. F. Hance, Pa.D. 
In the month of May, 1864, Mr. Sampson detected, growing in 
considerable abundance, in deep pools amongst the low undulating 
