CAMPHORIFEROUS ESSENTIAL OILS, ETC. 
23 
gravity than the standard, we might be led to infer, either 
that they had been obtained from old plants, or that the oils 
themselves were old, which is very frequently the case. In 
evidence of the above, the following is a comparison between 
the specific gravities of some old and recent essential oils, viz.: 
01. gaultheriae, 1.1920 ~) f 1.1700 
01. cinnamoni, (cassise,) 1.0935 ! ^ c J 1.0498 
Professor Hare* has tested the action of sulphuric acid on 
three of the volatile oils, — those of sassafras, cinnamon, and 
cloves, — resulting in the evolution of as many resinous sub- 
stances, to each of which he has given a name. I have car- 
ried out his idea, with as many of the essential oils as were 
procurable ; all of which yield resins, more or less charac- 
teristic, while at the same time they agree in the general pro- 
perties. 
They all communicate a tinge to concentrated sulphuric 
acid, varying from pale brown to crimson ; and they are all 
soluble in alcohol and in ether, and when free from adher- 
ing oil, are nearly inodorous. They were prepared by act- 
ing on the oils with sulphuric acid, and subsequently 
washed with ammonia, nearly as directed by Professor 
Hare. 
The resins produced from the oils of hemlock, rue, berga- 
mot, camphor, and wormwood, vary in color from black to 
grayish brown ; those of lavender, neroli, valerian, origanum, 
lemon, horsemint, rosemary, peppermint, cubebs, turpentine, 
and pennyroyal, are greenish brown; and those of simple mint, 
fennel, tansy, savin, wormseed, carra way, juniper, anise, roses, 
bitter almonds, cajuput, and jasmine, from pale reddish brown 
to deep red. 
Of these, those of the oils of fennel, tansy, camphor, anise, 
juniper, and wormseed, communicate dark red tints to sul- 
phuric acid, the two former imparting almost as deep a hue 
as the resin of cinnamon. 
OL caryophylli, 
01. foeniculi, 
* See two papers by Professor Hare, Amer. Jour. Pharm. vol. iii. 
