144 SOAPS AND PROTEINS 



general statements is illustrated in Figs. 83, 84, 85, 86, 87 

 and 88. 



Fig. 83 shows, when compared with Fig. 77, that the foaming 

 of 2 m potassium soaps at four different temperatures docs not 

 begin until potassium caprylate is reached. This soap foams 

 slightly at 8 C. but loses this quality as soon as the temperature 

 is increased. The first potassium soap to show a lasting foam 

 at the several temperatures is the caprate (the tubes 8 of Fig. 



FIGURE 81. 



83). Fig. 84 shows the appearance of these tubes two hours 

 later. The foam has disappeared entirely from the only caprylate 

 which showed foaming qualities and from the caprate kept at 

 the highest temperature. 



Figs. 85 and 86 show the behavior of potassium soaps of the 

 acetic series at the concentration m. The caprate is the first 

 in the series to foam, but the laurate and myristate also foam: 



