246 ON THE VOLATILE OIL OF BETULA LENTA, ETC. 
action the acid acts on the methylic base of the oil, setting 
the salicylic acid at liberty. This is an interesting fact and 
deserves attention. 
Gaultherin. — The dry bark of the Betula lenta does 
not possess the peculiar odor of its volatile oil, which latter 
is only developed by the contact of water. The analogy of 
this fact to that of the wild cherry bark, rendered it probable 
that a principle existed in the bark, which by its decompo- 
sition, yielded the oil. When the powdered bark is treated 
with cold alcohol of 95 per cent, by maceration and dis- 
placement, until it is exhausted, the residue of the bark no 
longer gives an odor of Gaultheria when moistened with 
water. If the alcoholic liquid be evaporated to an extract, 
and a portion of it be mixed with a part of the exhausted bark 
in water, the peculiar odor of the volatile oil is immediately 
developed, and by distillation a liquid is obtained which is 
colored purple by the persulphate of iron, and otherwise 
reacts like the oil of Betula lenta. 
Gaultherin does not appear to exist in the Gaultheria 
procumbens. The leaves of that plant were dried, powder- 
ed, and treated like the bark of Betula lenta, but they did 
not yield that principle. The leaves of the Gaultheria. 
when long kept, lose their odor, and mixture with water 
does not revive it, as with Betula lenta; hence it would 
seem that the salicylate of methylene is an immediate 
product in the Gaultheria procumbens, whilst in the 
Betula lenta it is secondary. 
In order to obtain this principle as pure as possible, the 
alcoholic extract of the bark is treated with water, which 
leaves the resin and fixed oil. The dark red liquid thus ob- 
tained, containing tannin, extractive, and saccharine matter, 
is then treated with an excess of hydrated protoxide of lead, 
until these substances are separated, and the transparent, near- 
ly colorless liquid obtained by filtration, is carefully evaporat- 
ed. A transparent gummy mass results, which almost wholly 
dissolves in alcohol of 97 per cent. The alcoholic solution, 
