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one or more of which contains its valuable properties. 
In a few cases, as that of lemon-peel, the oil is removed . 
by expression. Volatile oils have many uses in medicine 
and the arts, being largely used in perfumery and in 
flavoring. 
A perfume consists of an agreeably fragrant volatile 
substance, so held by another substance, the menstruum, 
that when exposed to the atmosphere, it will evaporate, with 
or without the menstruum, and come into contact with 
the olfactory nerves, with the result of producing a pleasant 
smell, or of concealing a disagreeable one. ‘These aromatic 
substances are usually only slightly soluble in water. 
Nevertheless, many aromatic waters, such as lavender and 
orange-flower water, are used as perfumes. More fre- 
quently, they are held in alcohol, bay rum being an illustra- 
tion of this class. 
Sometimes the perfume is made by mixing the men- 
struum with the article in which the fragrant substance 
naturally exists, such as roses or orange flowers, and 
distilling by the application of heat, the fragrant substance 
thus being driven out of the flowers and entering the 
menstruum. In other cases, the fragrant substance, having 
previously been distilled from the flowers, is merely mixed 
with the menstruum. A fat, such as lard, is often made to 
take up the fragrant principle by placing the flowers or 
other articles between thin layers of the fat and allowing 
them to remain until their oil has permeated the latter, 
the resulting substance being known as a pomade. 
Unless otherwise stated, the crude substances of this 
series were donated by J. L. Hopkins & Co., of New York, 
and the volatile oils by Fritzsche Brothers, of Leipsic and 
New York. 
1729. Male fern.—The rhizome of Dryopteris Filix-mas (L.) Schott. (Polypodia- 
ceae—Polypody Family). Native of the north temperate zone. 
1730. Oil of male fern.—A volatile oil distilled from the preceding. 
