12 MATER i A MEDIC A AND THERAPEUTICS. 



colouring matter returned, and the whole evaporated 

 'down to the required consistence. Ex. : Extractum 

 Aconiti. 



2. Fresh extracts are prepared like green extracts, 

 but there being no colouring matter, the juice is heated 

 at once to 212 Fahr. to coagulate the albumen, filtered, 

 and evaporated at 160. Ex.: Extractum Taraxaci. 



3. Aqueous extracts are prepared from drugs by 

 the action of cold, hot, or boiling water on dry drugs, 

 and subsequent evaporation to a proper consistence. 

 Ex. : Extractum Calurnbse, Extractum Gentianse. 



4. Alcoholic extracts are prepared by the action 

 of rectified spirit, rectified spirit and water, or proof 

 spirit on dry drugs, and evaporation to a proper con- 

 sistence. Ex. : Extractum Physostigmatis. 



5. Ethereal extracts are prepared in various ways ; 

 viz. (a) By percolating with ether and evaporating the 

 product : Extractum Filicis Liquidum. (6) By making 

 an alcoholic extract, macerating this in ether, and 

 evaporating : Extractum Mezerei JEthereum. (c) By 

 washing the drug free from oil, by percolation with 

 ether, before making an aqueous or alcoholic extract : 

 Extractum Ergotse Liquidum. 



6. Acetic extract. The only extract of this kind, 

 Extractum Colchici Aceticum, is made like a fresh 

 extract, but acetic acid is added to the crushed conns 

 before expression, and evaporation is arrested whilst 

 the mass is soft 



7. Liquid extracts are prepared by macerating 

 the drug in water, evaporating to form a concentrated 

 solution, and adding a little spirit to prevent decom- 

 position. Ex. : Extractum Pareirse Liquidum. The 

 process is modified in the case of ergot and filix mas, 

 as described under ethereal extracts. 



The consistence of extracts varies much. Some 

 are liquid ; four are solid, viz. those of aloes 

 (2), hsematoxylum, and krarneria ; five are soft, viz. 



