THE VOLATILE PART OF PLANTS. 93 



According to Hoppc-Scylcr, (Ned. Chcm. Hitters., I,) the phosphorized 

 principle of oil of maize, and of the brain, nerves, yolk of eggs, etc., is 

 primarily the substance discovered in 1864 by Liebreich, in the brain, 

 and termed lrotagon. It is a white crystallized body, having the 

 following composition : 



Carbon, 67.2 



Hydrogen, 11.6 



Nitrogen, 2.7 



Phosphorus, 1.5 



Oxygen, 17.0 



100.0 



Its formula is One, H 24 j, N 4 , P, O 22 . When heated to the boiling point 

 it is decomposed, and yields among other products glycerin, phosphor- 

 ic acid, and stearic acid. (Ann. Ch. Ph., 134, p 30). 



Saponification. The fats are characterized by forming 

 soaps when heated with strong potash or soda-lye. They 

 are by this means decomposed, and give rise to fatty 

 acids, which remain combined with the alkalies, and glyce- 

 rin, a kind of liquid sugar. 



EXP. 41. Heat a bit of tallow with strong solution of caustic potash 

 until it completely disappears, and a soap, soluble in water, is dbtained. 

 .To one-half the hot solution of soap, add chlorhydric acid until the 

 latter predominates. An oil will separate which gathers at the top of 

 the liquid, and on cooling, solidifies to a cake. This is not, however, 

 the original fat. It has a different melting point, and a different chemi- 

 cal composition. It is composed of one or several fatty acids, corre- 

 sponding to the elementary fats from which it was produced. 



When saponified by the action of potash, stearin yields 

 stearic acid, C 18 H 36 O a ; palmitin yields palmitic acid, 

 C* H 32 O 2 ; and olein gives oleic acid, C 18 H 34 O 2 . The 

 so-called stearin candles are a mixture of stearic and 

 palmitic acids. The glycerin, C 3 H 8 O 3 , that is simulta- 

 neously produced, remains dissolved in the liquid. Glyce- 

 rin is now found in commerce in a nearly pure state, as a 

 colorless, syrupy liquid, having a pleasant sweet taste. 



The chemical act of saponification consists in the re-arrangement 

 of the elements of one molecule of fat and three molecules of water in- 

 to three molecules of fatty acid, and one molecule of glycerin. 



Palmitin Water. Palmitic acid. Glycerin. 



C 5 iII 98 O a + 3(H a O) - 3 (C 16 H 32 2 ) + C 3 H 8 8 . 



