132 WILLIAM SEIFRIZ 



during the sixth or seventh interval of shaking, i.e., after 60 or 70 shakes. 

 The dispersed water particles are from less than \ to 30 m in diameter, 

 and exhibit no Brownian movement. The emulsion is very thick, the 

 viscosity being too high to conveniently measure with a capillary viscosi- 

 meter. No current will pass through the original emulsion at 52 volts. 

 The emulsion reverts readily with NaOH. One drop (0.033 cc.) of 

 M NaOH will bring the emulsion to the reversal point. Two drops 

 will cause complete reversal into an oil-in-water emulsion. If to this 

 emulsion one drop of M BaCl 2 is now added, the emulsion immediately 

 reverts to its original type, i.e., to a water-in-oil one, the ammeter 

 reading being again 0.00. By alternately adding 1 or 2 drops of M 

 NaOH and M BaCl 2 , it was possible to reverse an emulsion with a casein 

 emulsifier eight times. 



Gliadin. This alcohol soluble protein, which comes from wheat 

 gluten, was kindly given me by Dr. Thomas B. Osborne of the Connecti- 

 cut Agricultural Experiment Station. The solution received was a 

 5 per cent concentration of gliadin in 70 per cent alcohol. Two cubic 

 centimeters of this were dispersed in 98 cc. of water. The colloidal 

 solution thus obtained was used as the emulsifying agent. The resulting 

 emulsion is a water-in-oil one. The emulsion forms very quickly, 

 usually within the first ten shakes. The color of the original emulsion 

 is red (the oil phase being stained with Sudan III), indicating clearly 

 that oil is the continuous phase. If the emulsion is not completely 

 formed a slight (3 milliampere) reading of the ammeter may be obtained. 

 Ordinarily, however, the ammeter registers zero. 



A water-in-oil emulsion with 0.1 per cent gliadin as the aqueous phase, 

 is readily reversed by 0.3 to 0.5 cc. of M/10 NaOH into an oil-in-water 

 emulsion, with a milliamperage of 6 or 7. Two-tenths cubic centi- 

 meter of M/10 BaCl 2 will again reverse the emulsion into its original 

 form, with a zero reading of the ammeter; and 0.5 cc. of M/10 

 NaOH will throw it back again to an oil-in-water emulsion with 

 a milliamperage of 10. By keeping the emulsion near the reversal point 

 it can be reversed again and again by very small quantities of salt and 

 base. When thus kept near the reversal point, 0.07 to 0.1 cc. of M/10 

 BaCl 2 will produce complete reversion into a water-in-oil system with 

 which no reading of the milliameter can be obtained, and 0.15 to 0.3 

 cc. of M/10 NaOH will cause reversal in the opposite direction with a 

 milliamperage increasing with each reversal, i.e., with increasing con- 

 centration of electrolytes in the aqueous phase. At the eleventh rever- 

 sal the milliamperage was 60. 



Lecithin. Lecithin is a lyophilic "lipoid" readily dispersed in water. 

 The lecithin used came from Merck. One gram was dispersed in 100 

 cc. of water. This sol makes a very good emulsifying agent. The 



