OMICHOLIC ACID. 159 



5. Alkalies in excess resolve it into phosphate, oleate, 

 and glycerine. 



6. Heated on platinum foil it blackens, burns, and 

 leaves a charcoal containing phosphoric acid corre- 

 sponding to 2% of phosphorus in the original substance. 

 The phosphorus may also be determined by decom- 

 posing the compound by fuming nitric acid, when the 

 phosphoric acid is found in the aqueous layer. 



7. Oleophosphoric acid differs from oleine in being 

 insoluble in cold absolute alcohol. It has not yet been 

 obtained pure, nor can it be produced artificially, but a 

 similar compound of sulphuric acid and oleine is known. 



Omicholic Acid, 15 H 32 N0 4 (See Uromelanine) . 1. 

 Boil Urochrome (q. v.) with dilute sulphuric acid until 

 the fluid assumes a dark red colour ; add water, reddish 

 brown flakes are precipitated, collect those flakes and 

 extract with boiling alcohol ; filter the solution when 

 cool, and concentrate the filtrate and pour into cold 

 water ; a red powder is deposited ; collect this powder 

 and extract with ether, and filter. 



2. Allow the ethereal solution to evaporate sponta- 

 neously ; the Omicholic acid is left as a resinous syrup 

 mixed with Omicholine. 



3. Treat with ammonia; the omicholic acid is dis- 

 solved whilst the omicholine remains. 



4. Examine the ethereal solution of omicholic acid 

 with the spectroscope. It has a spectrum showing an 

 absorption band in the green. The ammonia solution 

 has no band. 



