ADSORPTION PHENOMENA 



205 



These data are plotted in fig. 1. 



To calculate the adsorption in the case of a glycocholate 

 solution the concentration of which is 0*2 per cent., it is neces- 

 sary to take the tangent to the curve fig. 1 corresponding to 

 this bulk concentration and express the result in absolute 

 units. Thus : 



da- _ g'S dynes per cm. 

 dc ~ o - oo2 grams per cm. 



= 4750. 



OiL A . Sop awaaoLC ate A- 

 Fig. 1. 



Writing 7 = 289, and expressing R in ergs, we obtain for 



the expression -^=j the value, 5-5 x io -8 grams per cm. 2 . 



It will be observed that the calculated adsorption is very 

 small. To measure such a quantity directly it is obviously 

 necessary to employ an exceedingly large adsorbing surface 

 of oil. This measurement was carried out (1) by forming an 

 emulsion of the oil in the glycocholate solution, in which case 

 the adsorption takes place at a surface of great curvature, 

 and (2) by passing the oil in the form of droplets (1-2 mm. 

 radius) through the solution, and estimating the change in 

 14 



