THE COLLOID-CHEMISTRY OF SOAPS 



53 



the bearing of this phenomenon on the general theory of 

 gelation. 



Fig. 42 shows the result of dissolving 1 gram of sodium stearate 

 or sodium oleate in 50 cc. of allyl alcohol at the temperature of 



FIGURE 41. 



boiling water and then cooling to 18 C. At the higher tempera- 

 ture the soap dissolves to form a " true solution "; as the temp- 

 erature falls, the soap becomes insoluble, but instead of forming 



FlUUlK 1-'. 



a gel it drops out as a crystalline mass. These experiments suffice 

 to show that not every soap solvent will yield a colloid system 

 with a given soap. We shall use these facts later for their bear- 

 ing upon the general theory of colloids. 



