122 GLYOEROPHOSPHORIC ACID. 



precipitate the baryum with just sufficient sulphuric 

 acid, and evaporate the nitrate in vacuo. 



2. From Brain. See Brain. 



3. From Lecithine. See Lecithine. 



4. From Egg -yelk. Dry in a water bath, extract 

 with boiling alcohol, evaporate to dryness, remove the 

 oil by draining and pressure between paper at a tem- 

 perature of 80C, and boil the viscid residue for 

 twenty-four hours with dilute caustic potash. Add to 

 the solution acetic acid in slight excess, and filter ; 

 precipitate the filtrate with lead acetate, decompose 

 the washed precipitate with hydrothion, evaporate 

 cautiously, and treat with a little silver oxyde to 

 remove hydrochloric acid, and the filtrate with hydro- 

 thion to remove silver. After driving off the hydro- 

 thion by evaporation neutralise the liquid with calcium 

 carbonate, filter, and concentrate. Calcium glycero- 

 phosphate will crystallise out, and may be purified by 

 recrystallisation. The acid may be isolated by preci- 

 pitation with oxalic acid and evaporation in vacuo. 



5. It is a very acid, gummy, uncrystallisable liquid, 

 very soluble in water and alcohol. The somewhat 

 concentrated aqueous solution decomposes by heating 

 into phosphoric acid and glycerine. 



6. Heated on platinum foil it burns with difficulty, 

 leaving a charcoal containing phosphoric acid. 



7. The baryum salt is very soluble in water, and is 

 precipitated by alcohol. 



8. The calcium salt crystallises in white pearly 

 scales, of the formula C 3 H 7 CaP0 6 , decomposes above 

 170C. Boiling with lime water resolves it into 



