RESIN, 147 



mot, the cells may be broken and the oil caused to flow 

 out by merely rubbing the rinds together ; or, the rinds 

 may be taken off by grating, and the oil separated from the 

 pulp by a light pressure, or by allowing the whole to remain 

 undisturbed for a few days, when the pulp will settle at the 

 bottom, and the oil remain floating above it. 



When these rinds are scraped with a bit of sugar, the oil 

 combines with it, forming an oleosaccharum ^ useful in giving 

 a pleasant flavor to liquors. 



With the exception of the oils of which I have just 

 spoken, all the volatile oils are extracted by distillation : 

 in this process the plant is put into the boiler of the alembic, 

 and covered with water ; v\ hen the water boils the oil rises 

 with the steam, and is condensed with that in the 

 worm of the still, whence they flow together into the 

 receiver : the oil which swims upon the top is separated 

 from the water, and this water, which has a milky appear- 

 ance, is again employed from preference in new distilla- 

 tions. 



It is customary to make use of a narrow, straight-necked 

 vessel as a receiver : the oil collects in the upper part ot 

 this, whilst the water passes off through a siphon in the 

 side, about four inches below the neck. 



In the south of Europe, where great quantities of the 

 volatile oils are prepared, the distillers place their portable 

 apparatus in the open air, in those places which offer a plen- 

 tiful harvest of aromatic plants; when these are exhausted 

 they remove elsewhere. 



The aromatic oils are employed particularly as perfumes, 

 and for this purpose are often combined with other eub- 

 atances. They are likewise used in the manufacture of 

 varnishes, from the readiness with which they dissolve 

 colors, and from their quick evaporation after being ap- 

 plied; 



ARTICLE VL 



Resin. 



The occurrence of resin is very common throughout the 

 whole vegetable kingdom, but it is from those trees which 



