id 



SOAPS AND PROTEINS 



ent fatty acid radicals. The re- 

 sults in the case of the sodium 

 .W/.s of the acetic add series are 

 shown in Fig. 6. All the soaps 

 were so made that in the end one 

 mol of the soap was produced 

 in the presence of one liter of 

 water. 



As Fig. 6 shows (the formate 

 and acetate have been omitted) 

 the lowermost members of this 

 series yield only molecular ("true") 

 solutions under these experiment- 

 al conditions. The solutions of 

 sodium caprylate and caprate, 

 as here prepared, show decidedly 

 lasting foams, indicating that they 

 are approaching colloid proper- 

 ties. Beginning with sodium 

 laurate, all the remaining soaps 

 yield solid white gels. 



The same general truths are 

 shown for the potassium salts of 

 the acetic acid series in Fig. 7. 

 Here again the lower members 

 yield only " true " solutions, the 

 middle ones liquid colloids, the 

 upper ones solid gels. 



These two groups of experi- 

 ments show that under otherwise 

 fixed conditions the water-absorbing 

 power of any soap depends upon 

 the nature of the fatty acid in the 

 soap, increasing with its height in a 

 given series. 



To get a more accurate meas- 

 ure of the amounts of water that 

 can thus be held by a series of dif- 

 ferent sodium soaps we made the 

 following experiment. 



