[ 6 7 ° ] 
His, at leafl, feems to be the method (9), which the 
dyers at Florence ufed. From both thefe accounts, 
urine and pot-afh appear to be the principal ingre- 
dients ufed in extracting its colour. 
Many other plants of this genus contain the fame 
tophaceous matter as the orchel ; and upon trial have 
been found to ftrike a good colour. Micheli, after 
he has related the preparation of the orchel , fuggefts 
the fame thing ; and M. Hellot, in the treatife 
before mentioned, tells us, there are many other 
modes, which will give as good a colour as the 
orchel. In fa6t, he adds, that M. Bernard de Juflieu 
brought him fome from the foreft of Fontainbleau, 
which, upon experiments with urine and lime, took 
a purple colour. In the fequel of this memoir we 
Ihall point out fome of thefe kinds. M. Flellot has 
given us a procefs, which he made ufe of for dif- 
covering whether any of thefe lichens would yield a 
red or purple colour. It is as follows : “ Put about 
<c two drachms of any of thefe lichens into a little 
“ glafs jar : moiften it well with equal parts of 
ftrong lime-water, and volatile fpirit of fal ammo - 
“ niac s tie a wet bladder clofe over the top of the 
“ veflfel, and let it ftand three or four days. At the 
“ end of this time, if the lichen is likely to anfwer, 
tc that fmall quantity of liquor, which you will find 
“ in the glafs, will be of a deep crimfon red ; and 
“ the plant will retain the fame colour when the li- 
a quor is all dried up. If neither the liquor nor the 
“ plant have taken any colour, it is needlefs to make 
■ u any further trials with it.” This procefs is fimple 
(9) Nova Plant. Gcner. p. 78. 
and 
