104 ON THE PRESENT USE OF LICHENS AS DYE-STUFFS. 
manufacture of Lichen- al in Wis is, perhaps, now more extensive 
and more flourishing than e 
. That “ French sou Y^ ' Ordill and Cudbear are successfully 
competing with the aniline and all other colours of their class hitherto 
introduced. 
8. That the commercial sources of ** Orchella-weeds” of the finest 
quality,—the varieties of Roccella fuciformis,—may yet be greatly mul- 
tiplied ; and are so far from being exhausted, that they cannot yet be 
said to be fully developed. 
I propose limiting myself at present, for brevity's sake, to some illus- 
trations only of the present use commercially of Lichens as Dye-stuffs. 
Commercial Dye-lichens and Lichen-dyes. 
At present the most interesting form of Lichén-dye,—that which is 
typical of the most recent substitutes for the more familiar Orchill and 
Cudbear of former times,—is what is denominated in this country 
French purple. This substance, which appears to be a lime- (or 
alumina-) lake of our common Orchill, was introduced to commerce by 
Messrs. Guinon, Marnas, and Bonnet, of Lyons, by whom it was ex- 
hibited in London in 1862. It has this great advantage over Orchills, 
that it is much faster and less sensitive to the action of acids, while it 
yields very fine and pure mauve and dahlia tints—especially on silks— 
without the use of mordants, properly so-called. To render it avail- 
able, however, for dyeing, the lake must be decomposed, and the 
colouring matter set free by means of oxalic acid and ammonia. 
Professor Hofmann, of London, in his report on “ Chemical Products 
and Processes,” exhibited in London in 1862 (in the International 
Exposition), makes the strong statement, that “ so far as regards fast- 
ness and resistance to the influence of light, French purple is certainly 
not inferior to aniline purple.” The chief colouring-matters with 
which it has to compete are, besides the coal-tar dyes, cochineal, 
indigo-carmine, and ultramarine. But it appears to compete success- 
fully; and there seems no reason to doubt that, with the progress of 
manufacturing chemistry, the Lichen-dyes will continue to hold their 
own permanently against these other colouring-matters which may, for 
the time, enjoy a higher reputation in the world of fashion. The 
manufacturing experiments of the French on the large scale have 
