THE COLLOID-CHEMISTRY OF SOAPS 149 



palmitate and stearate tubes (the series 9, 10, 11, and 13 of Fig. 

 87) are compared with the similarly numbered tubes of Fig. 85 

 that these potassium soaps foam decidedly better at the m/2 

 concentration than at the higher concentration. The foams also 

 last well, as evidenced when Fig. 88 is compared with Fig. 87. 

 Fig. 88, taken two hours after the foaming was produced, again 

 shows that the persistence of a foam rises with the position of a 

 soap in the series and falls with increase in temperature, once the 



FIGURE 88. 



soap/water systems have been warmed above their liquefaction 

 points. 



