Directions foe Percolation 



1. Moisten the powder and allow to macerate the specified 

 length of time. 



2. Place a small tuft of purified cotton in the neck of the per- 

 colator and moisten it with a few drops of the menstruum. 



3. Transfer powder to a sheet of thick paper and pour the whole 

 quantity from the paper to the percolator at one time. 



4. Shake or jar the percolator gently until the powder is level 

 and leave for from 15 minutes to .several hours according to di- 

 rections. 



5. Pack the powder more or less firmly according to directions 

 and the character of the substance and menstrum. In general the 

 coarser the substance and the more alcoholic the menstruum, the 

 greater the force may be employed. 



6. Adjust cork with tube in the neck of the percolator. 



7. Place a sheet of filter paper on top of the powder and hold 

 it in place with a glass stopper or other glass weight. 



8. Pour on menstruum through a funnel reaching nearly to 

 the surface of the paper. 



If the above conditions are observed, the menstruum will pene- 

 trate the powder until it has reached the cork. 



When the liquid has reached the neck of the percolator, close 

 the clamp which controls the flow of the percolate, and cover the 

 percolator to prevent evaporation. Then allow to macerate as 

 directed. 



To begin percolation, loosen the clamp sufficiently to allow the 

 liquid to drop very slowly. 



Rate op Flow: — The Pharmacopoeia directs that in making 

 fluidextracts, the rate of flow where 1000 igrams of the drug are 

 used should not exceed more than ten drops a minute : for official 

 tinctures and other fluids of about the same strength, twenty drops 

 per minute and the word slowly means a rate of flow corresponding 

 to this. With the amounts of powdered drugs used in this course 

 the rate of flow for fluidextracts should be about 2 drops per mim- 

 u-te and for tinctures about 3 to 4 drops per minute. 



Expression. This is the process of separating a liquid from 

 a solid by pressure. It is especially used in pharmacy for the 

 purpose of separating a liquid from a drug residue (marc) left 



