72 BITTER SECRETION. 



and are often highly aromatic and odoriferous. 

 One of the most exquisite of these is afforded 

 by the Cinnamon hark. They exist in the 

 highest perfection in the perfumed effluvia of 

 flowers, some of which, capable of combi- 

 nation with spirituous fluids, are obtainable 

 by distillation, as that of the Lavender and 

 Rose ; while the essential oil of the Jasmine 

 is best procured by immersing the flowers in 

 expressed oil which imbibes and retains their 

 fragrance. Such Expressed or Gross Oils, as 

 they are called, to distinguish them from es- 

 sential oils obtained by distillation, are chiefly 

 found in the seeds of plants. In the pulp of 

 the Olive indeed they occur in the form of 

 an emulsion, mixed with watery and bitter 

 fluids, from which the oil easily separates by 

 its superior lightness. These expressed oils 

 are not soluble in spirits or water, though by 

 certain intermediate substances they may be 

 rendered capable of uniting with both. 



The Bitter secretion of many plants does 

 not seem exactly to accord with any of the 

 foregoing. Some facts would seem to prove 

 it of a resinous nature, but it is often per- 

 fectly soluble in water. Remarkable instances 



