Dyeing Properties of Lichens. 229 
III. The collection and transport of lichens for the pur- 
pose of examining their colorific powers is very easy, viz. :— 
a. By simple desiccation and packing. 
b. By drying and pulverizing. 
c. By precipitating the colorific principles from a lime 
solution or a decoction by acetic or muriatic acid. 
IV. The colour of the thallus and that obtained by the 
action of Stenhouse’s or Helot’s tests on solutions of the 
lichen-colorific-principles do not always correspond in tint ; 
more frequently the reverse obtains ; hence it is impossible 
from the colour or other external character of the thallus of 
a lichen to predicate the nature of the reaction of its alco- 
holic solution with chloride of lime, or the tint it will yield 
on ammoniacal maceration. 
V. The lichens richest in colorific principles, capable of 
yielding valuable colouring matters, are crustaceous and 
foliaceous species of a pale or whitish colour—whose alcoholic 
or aqueous infusion is nearly devoid of colour—which grow on 
rocks or stones, and in mountainous countries, or on sea-coasts. 
VI. The lichens most devoid of the same principles are 
species having a showy foliaceous thallus—attaining a con- 
siderable size—whose alcoholic and aqueous solutions are 
generally of the same colour with the thallus—and which 
grow on trees and in woods. 
VIL. The colours educible from lichens are liable to be ma- 
terially affected, both as to quantity and quality, according 1o— 
a. Age of the specimen operated on, i. ¢., length of period 
that has elapsed since collection and desiccation. 
6. The geologic or other nature of its habitat. 
ce. The nature of its basis of support—whether moist or 
dry—rock, stone, tree, or earth, &e. 
d. The amount of exposure to sun-light and atmospheric 
oxygen. 
. Amount of moisture in the air. 
. Temperature of the locality. 
. Elevation above the sea. 
. Season and vicissitudes of the weather. 
. Longitude and latitude in the two hemispheres. 
. Decomposition of organic bodies in vicinity. 
~S PQ DO 
