6 SOAPS AND PROTEINS 



In commercial soap manufacture, this surface layer of soap (bring- 

 ing with it a certain amount of water, of excess alkali or salt, and 

 some glycerin if the TWITCHELL process is not the one employed) 

 is separated from its lye, is permitted to cool and after more or 

 less handling is made into " cakes " for trade purposes. 



2. Soap Making as a Colloid-Chemical Problem. The Fatty 

 Acids of the Technical and Theoretical Chemists 



Until the eighties of the last century, soap itself and the proc- 

 esses of its manufacture were looked at from a purely " chemical " 

 point of view. The soaps were, in other words, regarded as ordi- 

 nary salts which were either " soluble " or " insoluble " in 

 water or other solvents. When soluble, the resulting soap 

 " solutions " were generally regarded as obeying the laws char- 

 acteristic of the ordinary solutions. In 1888 FRANZ HOFMEISTER 1 

 chose the soaps in general and sodium oleate in particular as 

 materials of " colloid " nature and as fit substances upon which 

 to test out the dehydrating effects of various salts. The notion 

 that soaps were " normal electrolytes," that solutions of soap 

 follow the laws of osmotic pressure and in other ways comported 

 themselves as true solutions continued, however, into the nineties, 

 when F. KRAFFT 2 and his co-workers pointed out that the more 

 concentrated solutions of soap did not show the calculated depres- 

 sions of the freezing point or elevations of the boiling point of 

 true solutions. KRAFFT and his fellow workers therefore declared 

 these more concentrated soap solutions " colloid." Further 

 impetus to the development of this colloid-chemical notion of the 

 soaps was given by F. GOLDSCHMIDT and his pupils, 3 while various 

 articles subsequently written by J. LEiMDORFER, 4 F. BOTAZZI, 

 C. VICTOROW 5 and W. BACHMANN 6 may be said to have 

 established with finality that the soaps, in the concentrated form 



1 FRANZ HOFMEISTER: Arch. f. exp. Path. u. Pharm., 25, 6 (1888). 



F. KRAFFT and H. WIGLOW: Ber. d. deut. chem. Gesellsch., 28, 2573 

 (1895). 



F. GOLDSCHMIDT: Kolloid-Zeitschr., 2, 193, 227 (1908); F. GOLD- 

 SCHMIDT and L. WEISSMANN: Kolloid-Zeitschr., 12, 18 (1913). 



4 J. LEIMDORFER: Kolloidchem. Beihefte, 2, 343 (1911). 



* F. BOTAZZI and C. VICTOROW: Kolloid-Zeitschr., 8, 220 (1911), accessible 

 only as review. 



W. BACHMANN: Kolloid-Zeitschr., 11, 145 (1912). 



