THE COLLOID-CHEMISTRY OF SOAPS 



19 



one does not always get a crystalline product. The residue 

 is frequently shellac-like. Sodium caproate may therefore 

 be taken as the first soap in the series to show any water- 

 holding power. Sodium caprylate easily yields true solutions, 

 but if the amount of water is chosen correctly a beautiful 

 gel results at 18 C. The amount of water for one mot 



GELATION CAPACITIES 



PER MOL 

 OF DIFFERENT 

 SODIUM SOAPS 



WATER 



I 



C C 4 C, C. C, C. C, C. C, C, C. C Co 



FIGURE 9. 



of the soap must not exceed 200 cc. The matter is illus- 

 trated in the left hand bottle of Fig. 8. Sodium caprate still 

 yields a solid gel if 500 cc. of water are present to the mol of soap. 

 This is shown in the second bottle of Fig. 8. As we mount in the 

 acid series, the water-hold ii^ capacity grows tremendously. One 

 mol of sodium laurate will hold 4 liters of water; the same amount 

 of sodium myristate, 12 liters; of sodium palmitate, 20 liters; of 



