THE COLLOID-CHEMISTRY OF SOAPS 105 



Sodium chlorid produces the same general effects as potassium 

 chlorid, as shown in Table XLIX and Fig. 70. When the effects 

 of the two salts are compared it is seen that at the same molar 

 concentration the sodium salt acts more powerfully than the potas- 

 sium salt. Initial increase in viscosity, gelation and frank sepa- 

 ration of dispersion medium from the soap occur earlier through- 

 out in the tuljes of Fig. 70 than in those of Fig. 69. 



When ammonium* chlorid is employed in the same concen- 

 tration as that described above for potassium or sodium chlorid, 

 an initial increase in viscosity in the lower concentrations of the 

 ammonium salt is not to be observed. The first effect to be noted 

 is a slight clouding of the soap mixture as shown in Fig. 71 and 



FIGURE 71. 



Table L. As more of the ammonium chlorid is added a white 

 collar appears which grows progressively in thickness until the 

 whole contents of the tube appear white. Microscopic ex- 

 amination shows this collar to be an emulsion (of freed 

 acid in the remaining hydrated soap). 1 



The effects of magnesium and of calcium chlorid U|xm potas- 

 sium oleate are shown in TaMes LI and 1. 1 1 and l-'igs. 72 and 73. 

 i no increase in viscosity to be noted in either series but 



only a progressive fall. Tin- i- due to the formation of the SO- 



<tll<, I insoluble " calcium and magnesium soaps. It would 

 be better to say that the change is due to the formation of IMS 

 hydratable soaps for, as previous study has shown.-' the magnesium 

 and calcium soaps absorb much less water than the correspondiim 

 notassium soaps. Since magnesium soap holds more water than 



1 See ptffM 109, 136 and 176. "See MM* 10. 



