114 IVECES. 



rating the extract and allowing to stand, if possible at 

 C., silky crystals of excretine are deposited. 

 2. Excretine is very soluble in ether. 



Excretolic Acid (Marcet). 1. Obtain, as directed 

 under fseces and purify by dissolving in hot alcohol, 

 and allowing to deposit on cooling. 



2. It is an olive -coloured substance with an offensive 

 odour of faeces, very soluble in hot alcohol and in ether, 

 slightly soluble in cold alcohol, insoluble in water. The 

 alcoholic solution has an acid reaction. 



3. Heat on platinum foil ; it will burn with a lumi- 

 nous flame, evolving a fascal smell. 



Fceces. 1. Dry and, ascertain proportion of water 

 (73 to 75%). 



2. Exhaust a quantity of dried fseces with boiling 

 alcohol. (The residue will be insoluble in water and 

 ether and will consist mainly of food-remains and 

 insoluble inorganic matters.) Filter, and allow the 

 solution to stand. A deposit containing a peculiar fat 

 called excretolic acid (q. v.) will gradually form. 



3. Filter again, add milk of lime ; a brown precipi- 

 tate will fall. Dry the precipitate and extract it with 

 ether ; the ether on evaporation will leave excretine 

 (q-v.), which may be purified by crystallisation from 

 alcohol. 



4. The portion insoluble in ether must be boiled 

 with dilute hydrochloric acid, and 'the resulting 

 fatty acid (generally margaric) washed with water and 

 treated as directed under fats (q.v.). 



