4.34 GLYCERIN-PHOSPHORIC ACID. [BOOK I; 



of stearic acid, glycerin-phosphoric acid and choline, as shewn by the 

 following equation : 



CJI^NPO, + 3H 2 = 2 (CJ^OJ + C 3 H 9 P0 6 + C^NO,. 



Lecithin. Water. Stearic acid. Glycerin- Neuriiie. 



phosphoric 

 acid. 



This acid may be prepared by the decomposition of 

 tion"? giy- lecithin by means of caustic baryta, or synthetically in the 

 cerin-phos ~ following manner : 



phoric acid. Phosphoric anhydride is added in equivalent propor- 



tions to glycerin which is kept cool by a freezing mixture. 

 Much heat is evolved and the new acid is formed. According to the 

 author's experiments the yield of acid is extremely small. The solution is 

 diluted with water, neutralized with barium carbonate, filtered from the 

 large quantity of barium phosphate which is formed, and the filtrate is 

 exactly neutralized with dilute sulphuric acid. The filtrate from deposited 

 barium sulphate is concentrated in vacua at a low temperature; in this 

 manner a watery solution of the acid is obtained. This solution cannot 

 be concentrated beyond a certain point, as it decomposes. 



Pro erties Glycerin-phosphoric acid is a syrupy liquid possessed of 



and com- both an acid and sweet taste. It forms salts which are for 



pounds. the most part soluble in water, but insoluble in alcohol ; the 



lead compound is an exception to the former statement. 



The barium compound has the composition CaHyBaPOg. Tim die-hum 

 and Kingzett l describe a hydrate having the composition C 3 H 7 BaP0 6 H 2 O. 



The normal calcium salt has the composition C 3 H 7 CaP0 6 H 2 ; it 

 is less soluble in hot than in cold water, so that a solution appears to 

 coagulate when boiled, like a solution of albumin. An acid salt has 

 been described having the formula C 3 H 7 CaPO , C 3 H 9 P0 6 . 



A soluble zinc salt (C 3 H 7 ZnO 6 ) and an insoluble lead salt (C 3 H 7 Pb0 6 ) 

 also exist ; the latter is prepared by adding a solution of acetate of lead 

 to the barium compound. 



Constitu- ^. stu( tying the appended graphic formulae of 



tion> ' glycerin, phosphoric acid, and glycerin-phosphoric acid 



the reader will apprehend the view which is held of the 

 constitution of the last-named body. 



(OH (OH 



(1) C 3 H 5 ^OH (2) PCKOH 



(OH (OH 



C 3 H 5 (OH) 3 PO(OH) 3 



Glycerin. Orthophosphoric acid. 



1 Thudichum and Kingzett, " On glycero-phosphoric oxide and its salts, as obtained 

 from the phosphorized constituents of the brain." Journ. Cliem. Soc., July, 1876. 



