172 



sn.\PS AND PROTEINS 



ELL process, the fatty acids derived from them) are liquid 

 and that their saponification in consequence occurs quickly and 

 satisfactorily. Since only a few hours are necessary for complete 

 saponification by the hot process, this is preferred by the manu- 

 facturer to the cold process which 

 may require several days during 

 which his vats, frames and machines 

 are kept employed in the manufac- 

 ture of a single batch of soap. 



What has been written above may 

 be readily illustrated in laboratory 

 experiments which follow the prac- 

 tices of the soap chemist. In Fig. 

 93 are shown three beakers all con- 

 taining the same mixtures of cotton- 

 seed oil and sodium hydroxid, the 

 amounts having been so chosen as 

 ^ to yield a theoretically neutral soap. 

 In the first beaker on the left and 

 P in the middle beaker, the sodium 

 hydroxid solution has been poured 

 in a single " charge " into the oil, 

 the former having been left without 

 stirring, the latter having been stirred 

 immediately until the mixture showed 

 signs of stiffening. In the beaker on 

 the right, the sodium hydroxid was 

 added in three separate " charges" 

 (as is the practice in manufacturing) , 

 proper stirring following each new 

 addition of alkali. The photograph 

 was taken the following day. It 

 will be observed that without stirring- 

 only a thin soap layer (very dry) 



forms between the oil and the watery alkali and saponification 

 seems to come to a stop; that when added at once with 

 satisfactory stirring a fine clear soap is obtained; that when 

 added in three fractions a good soap but of less perfect appearance 

 results. We shall return to these findings later, but it is evident 

 at this time that from a low melting point fat a satisfactory soap 



