THE FATS. 13 



Emulsification of Fats. 



Certain poorly understood factors enter into the forma- 

 tion and preservation of an emulsion. Apparently the 

 viscosity of the menstruum and the condition of the 

 surface tension existing between that menstruum and the 

 globules form the fundamental physical requisites for the 

 obtaining of a permanent emulsion. Solutions of gums, 

 proteins, and soaps emulsify fats with varying degrees of 

 permanency. The mere presence of a soap in the solution does 

 not seem to render the fat particularly prone to emulsify; 

 the necessary condition is apparently the intermolecular forma- 

 tion of a soap in the solution as exemplified upon the addi- 

 tion of an alkali to fat containing some free fatty acid. An 

 emulsion formed in this manner is the most permanent of all 

 those induced by artificial means; a similar procedure takes 

 place in the emulsification of fat in the intestine. 



Make up the following mixtures in test-tubes: 



(a) 2 drops of neutral olive oil + 10 c.c. water. 



(6) 2 drops of neutral olive oil + 10 c.c. water + a few 

 drops of Na 2 C0 3 . 



(c) 2 drops of neutral olive oil + 10 c.c. of the soap solu- 

 tion. 



(d) 2 drops of neutral olive oil + 10 c.c. of an egg-albumin 

 solution. 



(e} 2 drops of rancid olive oil + 10 c.c. of water + a 

 few drops of Na-jCOg. 



Shake each tube approximately the same length of time 

 and compare the relative permanence of the various emul- 

 sions. Which conditions are the most favorable, and 

 why? 



