426 THE VEGETABLE WORLD. 
which has itself only a temperature of 100°C. In order to 
increase the temperature of the water, marine salt, which boils 
at 109°, is added. This has the effect of increasing the evapora- 
tion of the oil. But the practice has its disadvantages, and in order 
to prevent the plants from being burnt by coming into contact 
with the bottom of the furnace, it is usual to place on the lower 
bars of the furnace a diaphragm pierced with holes, which sup- 
ports the bed of leaves or flowers being distilled. 
The steam which is thus condensed in the worm of the alembic 
is a mixture of water and essential oil, in which however the oi 
performs only a small part. In order to separate the two liquids 
and secure the oil, a very ingeniously conceived vase, known as 
the Florentine receiver, is employed. This vase separates the oil 
from the water on the simple principle of their respective specific 
gravities. Oil is lighter than water, consequently it floats on the 
surface; and if the mixed liquid is received in a vase or jar 
having a tube rising from the bottom, but whose highest part is 
placed at a lower level than that of the neck of the vase, as long 
as the united liquid flows from the still, the water will sink to the 
bottom and flow off, while the oil will accumulate on its surface. 
The essential oils obtained by distillation from the Orange dis- 
solve readily in fatty oils or alcohol, but very imperfectly in 
water. The condensed water, however, which passes with the oil, 
is a true watery solution of the essences: in short, orange-flower 
water. It is very subject to putrefaction, which is indicated by 
the appearance of flocculent flaky matter accumulating at the 
bottom of the vessel in which it is kept, which is commonly called 
Orange Flower. These organic particles are the seeds of decom- 
position, which light and air are sure to develop. Kee 
The AmyRipAcezx are trees and shrubs abounding in balsamic 
resins, and haying all the appearance of the Orange, even to 1s 
dotted leaves, but the fruit forms a shell whose husk eventually 
splits into valve-like segments. The few known species are natives 
of tropical India, Africa, and America. The frankincense of 
Arabia is said to be the produce of Boswellia serrata. The Bal- 
samodendron myrrha, a dwarf shrub of Arabia, yields the myrrh 
of Mecca, and most plants of the order yield resins and balsams 
_ of great commercial and officinal value. 
