72 PHARMACY 



Examples : The resins of Burgundy pitch and podo- 

 phyllum. 



Balsamiim, pi. Bahama. — Balsams are oleo-resins with 

 the addition of either cinnamic or benzoic acids, or both. 

 They are solids or liquids. 



Examples : Balsam of Peru, balsam of Tolu. 



Gummus, pi. Gummi. — Gums are solid exudations from 

 plants. They are generally soluble in water, and their solu- 

 tions are precipitated by alcohol. 



Example : Gum acacia. 



Gum Besina, pi. Gum Besince, are solid exudations from 

 plants consisting of a mixture of a gum and a resin. 



Pharmaceutical Processes. 



Many of the technical methods are those employed in 

 chemistry, but of those more especially used in pharmacy 

 are the following : 



Trihcratioii is the process of rubbing or grinding coarse 

 materials in the dry state to reduce them to powder. 



Elutriation consists in suspending insoluble substances 

 in water and decanting the supernatant fluid, the coarser 

 particles settling to the bottom in the process. The method 

 is then repeated until fluid containing powder of the required 

 fineness is obtained, when the sediment is filtered and dried. 



Levigation combines elutriation with trituration. The 

 substance to be ground is put into a mortar with fluid and 

 the supernatant fluid is drawn off after comminution of the 

 former, leaving the larger particles behind. 



Maceration consists in soaking a coarsely powdered drug 

 in a liquid at a temperature of 60° to 70° Far. 



Digestion is the latter process conducted at a higher 

 temperature, but less than the boiling point. 



Lixiviation is the method by which the soluble sub- 

 stances are obtained from ashes by the percolation of water 

 through them. The resultant solution is termed a lye. 



