142 LEUOIO ACID. 



precipitate ether extracts a considerable quantity of 

 lead oleate. The oleic acid is purified by crystallising 

 the baryum salt from boiling alcohol ; and decom- 

 posing the pure salt by hydrochloric acid. 



10. The lead salts, insoluble in ether, are decomposed 

 with hydrochloric acid and the free acids crystallised 

 from alcohol. They are finally obtained in white 

 glistening plates, melting at 56*7 C., corresponding in 

 composition with margaric acid, but containing pro- 

 bably a little stearic, though Heintz's process of frac- 

 tional precipitation with magnesium acetate fails to 

 effect a separation. 



11. Add alcoholic potash to an ether-alcohol solu- 

 tion of lecithine, and observe the precipitation of a 

 crystalline potassium salt. Hence lecithine, like glyko- 

 koll, is at once acid and base ; it is also, moreover, a 

 fat. 



Leucic acid, C 6 H 13 3 . 1. Pass nitrous acid 

 through a warm aqueous solution of leucine, add a 

 small quantity of leucine, evaporate to a syrup. Ex- 

 tract the syrupy residue with ether. Evaporate the 

 ethereal solution, when the leucic acid will crystallise 

 out. Press the crystals between blotting paper, when 

 nearly pure leucic acid is obtained. 



2. Leucic acid is soluble in water, alcohol, and 

 ether. It crystallises in colourless needles. Heat a 

 portion of leucic acid on a watch glass placed on a 

 water bath ; the acid will melt and volatilise, the sides 

 of the glass becoming fringed with crystals of the 

 sublimed acid. 



