THE COLLOID-CHI Ml- IKY OF SOAPS 



VIII 

 ON THE PHYSICAL STATE OF SOAP MIXTURES 



The experiments previously detailed show that the different 

 soaps differ among themselves in their absolute gelation capacities. 

 Speaking generally, linolates hold less of various " solvents " 

 (like water) than chemically comparable amount- of the oleates, 

 and these hold less than equimolar amounts of the stea rates. 

 Within the acetic series itself the lower members are less hydra- 

 table than the upper. The question therefore arose as to what 

 would happen if two such soaps of different hydration capacities 

 competed for a fixed volume of water. This is. in essence, the 

 question of technological importance when in commercial soap 

 manufacture a mixed soap is prepared in a limited volume of 

 water from the mixture of fatty acids obtained from any ordinary 

 mixed glycerid. 



A first experiment under this head was made by adding to 

 a hot sodium stearate solution increasing amount- of hot sodium 

 oleate. The actual mixtures are shown in Table XXII. 



The soaps were added to each other at the temperature of a 

 boiling water bath and, after careful mixin-j Mowed to cool 



to 18 C. The results of thi> experiment ;m shown in In 

 As indicated in the first bottle on the left, sodium oleate is. 

 at the maximal concentration employed in the series, a mobile 

 liquid. The bottle on the extreme riuhi -hows that sodium stea- 

 rate at the concentration cho>en i- a white solid. As evid- 

 in the bottles between then- ines. the presence of the 



sodium oleate interferes with the solidilieatimi <.f the whole mix- 

 ture. Even when then- mixtures are kept standing for months 

 they do not go solid. 



A second experiment under this heading was made by adding 

 sodium oleate to sodium palmitate The mixtun -. prepared in 

 i boilmi: water bath, had the composition -h..un m Table \\III 



The appearance of these mixture- ..?, .-..<, |j n g to 18 C. is shout. 



While the Hidium palmitate will t.y it -elf yield a white 

 solid, admixture with sodium oleate prove I does so 



