ON THE PRESENT USE OF LICHENS AS DYE-STUFFS. 105 
proved that all the defects of Orchill, which may be regarded as the 
type of the more valuable class of the Lichen-dyes, may be remedicd 
by simple chemical expedients. The great defect of Orchill has ever 
been its extreme liability to change under the influence of light and 
air, acids and alkalies, coal-gas, and other agents, to which dyed fabrics 
must be more or less exposed when made up in dress. The French 
have shown apparently that the beautiful purples and other hues of 
Orchill may be rendered perfectly fast or permanent ; and if in this re- 
spect they are placed on a par with aniline and other colouring matters 
of similar shades, they have no cause to fear competition on the score 
of brilliancy, beauty, or variety. I saw it recorded in 1850 that ** M. 
Clenchard, a French chemist, had recently patented a mode of using 
archil in the dyeing and printing of woollen and silk goods, in which 
the archil is combined with alkalies and lime, and applied to the woollen 
material with a more direct action than in the ordinary mode of its 
use." This seems to have been an intermediate stage in the produc- 
tion of French purple. Of the genus or species of Lichen used in the 
manufacture of that colouring-matter, I know nothing; but I doubt 
not it is one of the same “ Orchella weeds ” employed in this country 
in the preparation of Orchill and Cudbear. Nor am I prepared, even 
were it otherwise desirable, to give any information regarding the pro- 
cess of manufacture or application of the dye; though I have no reason 
to doubt that either differs essentially from what obtains in the cases 
of Orchill and Cudbear. 
The majority of Lichens formerly used in the preparation of Orchill 
and Cudbear in Britain have been given up by manufacturers, who now 
import almost exclusively Roccelle, or ** Orchella weeds," from tropical 
or subtropical countries, —and, for the most part, corticolous forms 
affecting the coast districts only. Generally this has arisen from the 
superior reputation of the corticolous Roccelle ; but there seems to bea 
solitary exception in the case of Parmelia perlata, which Mr. Burton, 
of London, tells me has a very high reputation, but is, nevertheless, 
scarce, and almost unknown in the market. All the ** Orchella weeds" 
known in European commerce, which have been submitted to me, are 
referable to forms of three variable and widely-distributed species, — 
. Roccella fuciformis, Ach., R. tinctoria, DC., and R. phycopsis, Ach., — 
none of which I regard as good species scientifically, the one passing 
gradually into the other. Of these, by far the most valuable is the 
