* 
COMPOSITZA. 287 
nearly 4 inch in. diameter, broadly hemispheric, pedicelled, 
secund, nodding, distant, in lax, long racemes terminating the 
branches, outer involucre bracts green hoary, inner broadly 
- scarious, receptacular hairs long, straight. (Fl. Br. Ind.) 
Chemical composition. —The Wormwoods contain absinthate 
of potash, a bitter substance, and a green volatile oil having 
a camphoraceous odour. Absinthin (C'*H*0%), the bitter 
principle is prepared, according to Luck, by exhausting the 
leaves with alcohol, evaporating to the consistence of a syrup, 
and agitating with ether. This ethereal solution is evaporated 
to dryness, and the residue treated with water containing a 
little ammonia, which dissolves the resin, and leaves the absin- 
thin nearly pure. To complete the purification it is digested 
with weak hydrochloric acid, washed with water, dissolved in 
alcohol, and treated with acetate of lead, as long as a precipitate 
is formed. After the removal of this precipitate by filtration, 
the excess of lead is precipitated by sulphuretted hydrogen, 
and the solution is evaporated. The absinthin then remains 
as‘a hard confusedly crystalline mass, possessing an extremely 
bitter taste. It is but slightly soluble in water, very soluble 
in alcohol, and less so in ether. It possesses distinctly acid 
characters, and is dissolved by potash andammonia, The 
Sal Absinthicum of the old Pharmacopeias was nothing more 
than carbonate of potash obtained by incineration of the plant. 
Absinthol, C!°H'60, isomeric with ordinary camphor, is the 
essential constituent of Wormwood oil, in which it is associated 
with a terpene, boiling below 160°, and a deep blue oil which ~ 
boils between 270° and 300°, and agrees in its properties with 
the blue chamomile oil examined by Kachler. Absinthol boils 
at 195° (Beilstein and Kupffer) ; at 200—205° (Alder Wright); 
217° (Gladstone). It differs essentially from camphor in its 
chemical reactions, not being converted into camphoric acid 
by oxidation with nitric acid, or into camphocarboxylic acid 
by the action of sodium and carbonic anhydride, and yielding 
- when fused with potash, a large quantity of resin, but no acid. 
Heated with phosphorus pentasulphide, it yields a considerable 
quantity of cymene, C!°H'*, identical with ordinary cymene— 2 
