188 SOAPS AND PROTEINS 



(and consequently will wash) even in relatively highly concen- 

 trated salt solutions, like sea water. The ordinary soaps rich 

 in the stearates and palmitates are useless under such circum- 

 stances, but the soaps of pure cocoanut oil and similarly con- 

 stituted fats work very well, for their entire soap series is largely 

 unaffected by sodium chlorid of the concentration found in sea 

 water. 



The settled soaps, which are smoother and decidedly less dry 

 than the curd soaps, owe these properties to the fact that they 

 hold more water than the latter. In the curd soaps the higher, 

 more solid and more crystalline soaps tend to fall out within 

 the more liquid ones, thus making for non-homogeneous soap 

 mixtures. When through such less perfect salting-out these higher 

 soaps are permitted to hold a larger fraction of water the whole 

 system appears clearer. Because of the higher water content 

 100 parts of the mixed fats commonly yield 175 to 200 parts 

 by weight of finished soap of the settled type. 



The half-settled soaps and the soft soaps are usually made 

 from the kettle contents direct. They differ from curd and settled 

 soaps in containing a still larger fraction of water commonly 

 250 to 600 parts of finished soap being obtained from 100 parts 

 of fat. The water in these soaps is held in part in the soap itself, 

 in equally large or even larger fraction, however, as water joined 

 to filler. The filler may be sodium chlorid but commonly it is 

 water-glass, excess alkali, sodium carbonate or sodium borate, 

 or two or more of these in combination. When sodium soaps 

 are filled with these materials a final product is obtained which 

 is still fairly firm. The distinctly soft soaps are usually potassium 

 soaps made from fats and fatty acids of low melting points. 

 These may be and are filled with potassium salts so that the 

 final yield may be as great as ten times the orginal weight of the 

 fat used. When the filling of potassium soaps is carried out with 

 sodium salts a partial conversion to sodium soap occurs which 

 tends to make the final product less soft. 



2 



In connection with the above facts which show how much 

 water different soaps may be made to hold, it is of interest to 

 introduce some experiments of C. STIEPEL 1 on the hygroscopic 

 1 C. STIEPEL: Fette, Oele und Wachse, usw., 100, Leipzig (1911). 



