194 SOAPS AND PROTEINS 



the production of systems similar to those previously discussed 

 in the salting-out of soaps. 1 The addition of sodium chlorid, 

 sodium carbonate, sodium borate and sodium silicate represents 

 7iothing but a process in which advantage is taken of the fact that all 

 these materials become hijdr tiled and emulsified in the hydrated soap, 

 thus yielding a stiffer and larger amount of mixture than would the 

 soap alone. In this fashion soaps can be sold with a larger abso- 

 lute water content and still appear " dry." Beyond this, the 

 merits or demerits of these fillers depend upon their specific 

 properties. Sodium chlorid is obviously entirely worthless, 

 it has no " softening " or other action upon water and its presence 

 interferes with the development of the washing effects of all soaps. 

 Sodium carbonate and sodium borate do aid in the first-named 

 direction and any excess thus unused yields an overplus of alkali 

 (after hydrolysis in water) which in its turn is possessed of those 

 advantages which any alkali may show in specific washing proc- 

 esses. The same may be said of sodium silicate (especially of the 

 commercially employed " water-glass ") which in addition to 

 the properties already mentioned yields colloid silicic acid when 

 diluted in the process of washing. The colloid silicic acid has 

 some of the properties which give to soap itself its* washing char- 

 acteristics. From these advantages must, however, be sub- 

 tracted certain disadvantages, as the fixation of the silicic acid 

 upon the washed materials and their " felting," the smarting of 

 the skin if the soap is used for toilet purposes, etc. 



How sodium chlorid produces the " fill " when added to any 

 soap has already been discussed. 2 How sodium carbonate, 

 sodium silicate, sodium borate and magnesium sulphate act in 

 entirely analogous fashion is illustrated for two pure soaps (sodium 

 and potassium oleate) in Figs. 96 and 97 and Tables LVII, LVIII, 

 LIX, LX, LXI, LXII, LXIII and LXIV, which detail the experi- 

 mental procedures followed. The purpose of the soap maker 

 is to obtain, from such otherwise liquid mixtures as are contained 

 in the control tubes shown at the extreme right of all these series, 

 the solid soaps found in tubes nearer the middle of each of the 

 series. The exact point at which such maximal stiffening of the 

 soaps is obtained varies, however, both with the type of soap 

 initially employed (whether a sodium or a potassium soap, for 

 example) and the nature of the salt used as " filler." At the same 

 1 See page 93. 2 See page 113. 



