156 
SELECTED ARTICLES. 
ART. XXV.— OF THE REACTION OF THE ESSENTIAL OILS 
WITH SULPHUROUS ACID, AS EVOLVED IN UNION WITH 
ETHER IN THE PROCESS OF ETHERIFICATION, OR 
OTHERWISE. By R. Hare, M. D., &c., &c., &c.* 
Having mixed and subjected to distillation two ounces of 
oil of turpentine, four ounces of alcohol, and eight ounces of 
sulphuric acid, a yellow liquid came over, having all the ap- 
pearance of that which is obtained in the process for making 
oil of wine, described in the preceding article. On removing, 
by means of ammonia, the sulphurous acid existing in the 
liquid, and driving off the ether by heat, a liquid remained, 
which differed from oil of turpentine in taste and smell, 
although a resemblance might still be traced. This liquid 
was without any sensible action on potassium, which contin- 
ued bright in it for many weeks. It proved, on examination, 
to contain a small quantity of sulphuric acid. I ascertained, 
afterwards, that in order to produce these results, it was suffi- 
cient to pour oil of turpentine on the mass which remains 
after the termination of the ordinary operation for obtaining 
ether, and apply heat. Subsequently it was observed that 
when the sulphurous ether was removed by heat or evapora- 
tion, without the use of the ammonia, the proportion of sul- 
phuric acid in the remaining oil w^as much greater. 
By subjecting to the same process several essential oils, I 
succeeded in obtaining as many liquids to which the above 
remarks were equally applicable. With some of the oils, 
however, similar results were, by this method, either totally 
or partially unattainable, in consequence of their reaction with 
the sulphuric acid being so energetic as to cause their decom- 
position before any distillation could take place. No product 
can be obtained by distillation with sulphuric acid and alcohol 
from the oil of cinnamon obtained from cassia. From the oils 
of sassafras and cloves, but little can be procured. 
However, in one instance, by previously mixing the oil of 
* From the American Philosophical Transactions. 
