§2 MATERIA MEDIC A. 



ration sold in the shops by this name, is 

 made by "dissolving a small proportion of 

 oil of peppermint in rectified spirit, or alko- 

 hol, that has been previously tinged with 

 some green colour. 



Essence of Mustard, appears to be 

 composed of camphor, oil of rosemary, and 

 oil of turpentine, which form a good stimu- 

 lating embrocation . 



ESSENTIAL OILS. The smell, taste, 

 and other qualities of vegetables, frequently 

 reside in a volatile oil, particularly in those 

 vegetables, or certain parts of vegetables, 

 that have a strong odour and taste ; as mint, 

 pennyroyal, peppermint, lavender, caraway 

 seeds, anise seeds, juniper berries, lemon 

 peel, santal wood, &c. This oil being vo- 

 latile, may be extracted, and procured in a 

 separate state, by distillation ; and as it con- 

 tains all the useful qualities of the substance 

 it was obtained from, is termed an essential 

 oilf which is found very convenient in me- 

 dicine, particularly for veterinary pur- 

 poses. 



ETHER. This is the »nost volatile liquid 

 we are acquainted with, and evaporates rea- 

 dily in the common temperature of the at- 



