78 
SELECTED ARTICLES. 
quantity of water in order to obtain the whole amount of oil, 
the very opposite of what happens when a mixture of water 
and essential oil is submitted to distillation. This occurs in 
consequence of the oils being held within the tissues of the 
plant, and because their proportion is small compared with 
the quantity of liquid which it is necessary to employ in order 
to saturate the plants, and also on account of the affinity ex- 
isting between them and the organic principles with which 
they are associated, which opposes their free separation. 
I poured upon three kil. of powered cubebs, seventeen 
litres of boiling water. I allowed it to stand eighteen hours, 
when I submitted to distillation. I arrested the operation 
when I had removed six litres of water; from its surface was 
procured seventy-five grammes of oil. I made another trial 
by adding to the water six kil. 500 grammes of salt, and I 
only obtained from it six litres and fifty grammes of oil. 
I made a new attempt with 3.700 grammes of cubebs, and 
twenty-five litres of water, without salt: the three first litres 
which passed by distillation, were productive of twenty-eight 
grammes of oil, and the three following of thirty -five grammes; 
in all sixty-three grammes. 
I repeated this trial, adding ten kil. of salt to the water; 
upon this occasion the first four litres gave twenty-five 
grammes of oil, and the two following eighteen, in all forty- 
three grammes. These two series of experiments demon- 
strated a fact which I far from expected, viz., that in the 
distillation of cubebs, the salt was a positive hindrance to 
the extraction of the essential oil. I cannot explain the fact; 
I only repeat it as I have noticed it upon successive trials. 
I shall not draw any conclusion from my experiments. If 
they have demonstrated that in the distillation of a mixture 
of essential oil and water, the operation is accelerated by the 
presence of salt, they have also proved, that in the distillation 
of cassia there is no advantage from it, while, as regards 
cubebs, it actually is a hindrance. My experiments most con- 
clusively show that the fabrication of the oils, which has been 
regarded as a well known operation, is, on the contrary, a 
