192 SOAPS AND PROTEINS 



II 

 FILLERS FOR SOAPS 



The extensive use of various fillers in the manufacture of soaps 

 necessitates touching upon this problem. It has been discussed 

 from many points of view. Various inventors and manufac- 

 turers have been honest in stating that the primary purpose of 

 such fillers is to meet the demand for " cheap " soap. Others, to 

 justify the procedure, emphasize the improved washing charac- 

 teristics of such soaps. Thus, a certain excess of alkali is actually 

 necessary in the soaps used for cleansing wool; an excess of 

 sodium carbonate acts as a softener, when, as is commonly the 

 case, untreated water containing calcium or magnesium is used; 

 water-glass, so commonly used to fill soaps, has colloid-chemical 

 properties similar to those of soap itself. On the other hand, 

 sugar tends to keep soaps transparent, while various sands and 

 pumice give them abrasive properties which may be of serivce in 

 various technologic procedures. The fact remains, however, that 

 " fillers " are commonly materials decidedly cheaper than soap 

 itself, that they tend, in general, to add weight or water to the 

 finished product and that in most instances, as one of our soap 

 chemist friends (C. P. LONG) puts it, they hasten the millennium 

 when the soap maker will be able to " get a bar of water to stand 

 alone." 



Our problem is fortunately not concerned with the necessities 

 or the moralities of the situation, but with the question of what the 

 mixture of soap with these materials means in the terms of colloid 

 chemistry. 



Most of the materials used to fill soaps (exclusive of inconse- 

 quential amounts of perfume, various coloring substances com- 

 monly employed, and certain " dirt " solvents like naphtha) may 

 be listed with some one of the following three groups. 



Group I. Sodium chlorid, sodium carbonate, sodium borate 

 and sodium silicate. 



Group II. Sugar solutions. 



