174: GLYCERIC ACID. 



Triolein, C 3 H 5 (O.C 18 H 33 0) 3 . It can be prepared from 

 liquid oils, for instance olive oil, when these are only 



gently heated with concentrated caustic potassa. 

 olorless oil, which becomes oxidized very easily in the 

 air. 



Succinin, C 3 H 5 j 92 C 4 H 4 2 is formed b ^ heating 

 equal parts of glycerin and succinic acid at 220. 

 Brown, hard mass, insoluble in water, alcohol, and 

 ether. 



B. MONOBASIC, TRIATOMIC ACIDS, C^H^O 4 . 



Glyceric Add. 

 C 3 H 6 4 = CH 2 (OH).CII(OH).CO.OH. 



Formation. From glycerin by oxidation, either with 

 nitric acid or with bromine and water ; from nitrogly- 

 cerin by spontaneous decomposition ; also probably by 

 heating dibrompropionic acid with silver oxide and 

 water. 



Preparation. 1 part glycerin is mixed in a glass 

 cylinder with somewhat more than an equal bulk of 

 water, and 1 part nitric acid of specific gravity 1.5 

 then introduced below it by means of a long-necked 

 funnel ; it is allowed to stand for five or six days and 

 then dissolved in a large amount of water, neutralized 

 with lead oxide and filtered boiling hot. The crude 

 lead salt, obtained by evaporating and allowing to cool, 

 is purified and then decomposed in an aqueous solution 

 by means of suphuretted hydrogen. 



Properties. Thick, uncrystallizable syrup, of a faint 

 yellowish color ; soluble in w T ater and alcohol in all 

 proportions. Monobasic acid. 



Calcium glyeerate, (C 3 IPO) 2 Ca -f 2H 2 0. Small, 

 white, concentrically-grouped crystals, easily soluble in 

 water, insoluble in alcohol. 



Lead glycerate, (C 3 IF0 4 ) 2 Pb. Hard, crystalline 

 crusts, difficultly soluble in cold water, more easily in 

 hot water. 



