23 



Maceration. — This is simpler than percolation. It consists in 

 simply leaving the drug in contact with the menstruum under suit- ■ 

 able conditions, for a certain, or sufficient length of time. If macer- 

 ation alone is used, a definite amount of the drug is placed in a con- 

 tainer with a definite amount or portion of the menstruum and left 

 a certain time, in many cases two weeks. The liquid is then strained 

 off, the residue (marc) expressed and the mixed extract filtered. 



The piocess is influenced by (1) degree of comminution. The 

 finer the drug the less time is required. (2) The higher the tem- 

 perature the quicker the solution. Different terms are given to 

 the process according to the degree of temperature employed. 

 Maceration is at room temperature. Digestion at 30°-40°C., Decoc- 

 tion at boiling temperature. The application of heat is objection- 

 able in certain cases because it injures some of the desired constit- 

 uents 'or on account of the evaporation of either the constituent 

 or solvent. (3) Time. Usually the longer the better. (4) Men- 

 struum. This must in each case be adapted to the particular drug. 



Percolation. — Percolation or displacement, is the process 

 whereby a powder contained in a suitaJble vessel is deprived of its 

 soluble constituents by the descent of a solvent through it. (Rem- 

 ington). , 



The solvent, which is poured on the top of the powder, in pass- 

 ing downward exercises its solvent power on the successive layers 

 of the powder until saturated, and is impelled downward by the 

 combined force of its own gravity and that of the column "of liquid 

 above it, minus the capillary force with which the powder tends 

 to retain it. A percolator is a vessel with a porous diaphragm be- 

 low, into which the drug, in the form of a powder is introduced, 

 and its soluble portions extracted by the descent of the solvent 

 through it. The menstruum or solvent is the liquid poured on top 

 of the powder. The liquid coming from the percolator, impreg- 

 nated with the soluble constituents of the drug is the percolate. 



The first portion of the percolate is always more dense, more 

 highly colored and contains the largest proportion of the soluble 

 principles, because the first proportion of the menstruum, in its de- 

 scent through the powder, has the first opportunity to come in contact 

 with the largest proportion of the soluble principles which are to be 



