FERMENTATION 209 



The drop will come to rest, and for a moment 

 both the drop and the surrounding liquid remain 

 clear. Very soon, however, the oil is covered 

 with a white layer, and through the soda solu- 

 tion spreads a white cloud which becomes denser 

 and denser until the oil drop, steadily diminish- 

 ing in size, floats in a milky white liquid. 



2. Eepeat the experiment, observing the oil 

 drop under a low power of the microscope. 



Note the extraordinary motion in the neigh- 

 borhood of the oil drop, and how the particles of 

 oil are thrown out in strong eddies. 



3. Examine the completed emulsion under a 

 higher power of the microscope. 



There appear exceedingly small fat drops of 

 very uniform size. The milky fluid is the finest 

 and most uniform emulsion. 1 



Rachford's Experiment. " Arrange a series of 

 watch glasses containing 0.25 per cent solution 

 sodium carbonate. Place in a test-tube 2 c.c. 

 neutral olive oil and 1 c.c. pancreatic juice (or 

 extract). Shake the tube and allow the juice 

 and oil to separate, then pipette a drop of oil 

 from the surface and place it on the soda solu- 

 tion in watch glass 1. Again shake the tube 

 and allow the oil and juice to separate, then 

 pipette as before, placing a drop of oil in watch 



1 Gad: Archiv fur Physiologic, 1878, p. 183. 

 14 



