ON CETRARINE. 
55 
more or less green, is to be thrown on a filter, and having 
been allowed to drain as little as possible, is to be pressed. 
To purify it, immediately after it is taken from the press, 
while yet moist, it is to be divided into small fragments, and 
in this state to be washed with alcohol or ether. It is then 
to be treated with two hundred times its weight of boiling 
alcohol, in which the organic matter, which has hitherto ac- 
companied it, is scarcely soluble. The greater part of the 
cetrarine precipitates gradually by the cooling of the alcoholic 
liquor; and by driving off the alcohol, the remainder may be 
obtained. 
Pure cetrarine is sometimes an absolutely white powder, 
like magnesia ; sometimes in the form of small globules 
united together in perfect tree-like forms, in which, however, 
M. Herberger could, by means of a microscope, perceive a 
crystalline texture. Slightly compressed, it presents a little 
silky lustre. It is light, unalterable in the air, inodorous; the 
bitterness is quick and very intense, especially when dissolved 
in alcohol. When left for sometime in water, it falls to the 
bottom of that liquid; it is imperfectly fusible; at the temper- 
ature of 125° C, it becomes brown; at a still higher temper- 
ature it gives off an acid oil of a reddish yellow color, which 
congeals on cooling; it blackens at 160° C, and leaves behind 
a large quantity of spongy charcoal, which burns freely in the 
open air. 
Its best solvent is absolute alcohol; 100 parts dissolves 
1.70 at the boiling temperature, but only 0.28 at 14° C. 
Alcohol of 0.83 dissolves 0.44 while boiling, 0.28 at 25° C, 
and only 0.04 at 14° C. It is less soluble in either boiling or 
cold water, in the essential oils, kreosote, &c. It is more so 
in acetic ether, and above all in sulphuric ether, of which 100 
parts dissolve 0.93 at the boiling temperature, and 0.57 at 14° 
C. It is insoluble in the fatty oils. Finally, all its solutions 
when tried by test papers appeared neutral. 
The action of the acids on cetrarine varied with their nature 
and degree of dilution. All the weak acids, the mineral as well 
as the organic acids, precipitate it. from its solutions in the 
