THE COLLOID-CHEMISTRY OF SOAPS 93 



to the more normal state by the administration of properly 

 chosen salts of the lighter metals. 1 



There exist, however, processes in pure soap manufacture 

 which have long made empiric use of the facts detailed above. 

 Instead of hydrolyzing fats with sodium or potassium hydroxid, 

 they are often hydrolyzed with calcium hydroxid. Under such 

 circumstances calcium soaps are produced which, as formed, have 

 little or no " washing " properties. The calcium soaps are then 

 converted into sodium or potassium soaps by treatment with 

 the carbonates of these metals. 



X 



ON THE "SALTING-OUT" OF SOAPS 2 



The previous pages 3 have shown that the absorption of water 

 by various pure soaps (and hence their physical state) depends 

 upon (a) the kind of base combined with a given fatty acid, or, 

 with a given base (6) upon the nature of the fatty acid. It is 

 the purpose of this section to describe the influence which the 

 addition of different electrolytes has upon their physical state. 

 We shall first describe the action of different salts upon a single 

 soap, namely, potassium oleate; later the effects of one salt 

 upon different soaps. The practical and tln-nrrtiral deductions 

 drawn from these materials will then be correlated with tho vari- 

 ous empiric practices of the soap manufacturer and allied scien- 

 tific studies in this field. 



1. On the 44 Salting-Out " of Potassium Oleate 



Tho potassium nlratr usrd in thi'sr r\|-nmi'nte was prepared 

 by adding to the molar weight of oleic acid expressed in grama 

 (282.27) 1000 cc. of a normal KOH solution. Th< <.l< u> acid 

 and the potassium hydroxid solution were heated separate! \ in 



a water hath and. at the temi>erature of the txiiling water, the 



> See pa*, 240 



MARTIN H. Fiacmm and MARIAN O. HOOKJCR: Science, 48, 143 (1018); 

 ibid., 4t, 615 (1019); Chem Engineer, 17, 225 and 253 (1010). See abo 



906, 



See par* 10 and 16; abo MARTIN H. Fncmn and MARIAN O. 

 r, 17, 155 (1010); ibid., 17, 184 (1010). 



