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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. 



