94 SOAPS AND PROTEINS 



oleic acid was poured into the potassium hydroxid. The mix- 

 ture was stirred and heated, with careful avoidance of evapo- 

 ration, until a clear, viscid liquid was obtained. Whenever our 

 stock or standard potassium oleate solution is mentioned in the 

 following experiments one prepared in this fashion is referred to. 

 At room temperature this stock is strongly alkaline to litmus 

 paper but phenolphthalein when added to it remains colorless. 1 



1. We tested out, first, the effects of adding different amounts 

 of water to the standard potassium oleate. The stock soap when 

 prepared as described has the viscosity of a syrup at ordinary 

 temperatures (18 C.). The addition to this of progressively 

 greater amounts of water merely serves to decrease its viscosity. 



2. We next tried the effects of adding progressively greater 

 amounts of various alkalies (KOH, NaOH and NH 4 OH) to the 

 standard soap. While from a chemical standpoint it matters 

 little how a mixture is made, it makes much difference from a 

 physical point of view as will be discussed later. When not 

 otherwise - specified the mixtures throughout these series were 

 made in the sequence in which they appear in the tables. In Table 

 XXVI, for instance, the water was first added to the soap and 

 mixed; then the KOH solution was added and the whole again 

 mixed. When not otherwise specified, all combinations were 

 made at room temperature which in the room employed and at 

 the time at which we worked (the winter of 1917 and 1918) 

 remained continuously close to 18 C. The descriptions and 

 photographs refer to the appearance of the mixtures twenty-four 

 hours later. 



Table XXVI and Fig. 57 show the effects of adding potassium 

 hydroxid. It is obvious that the control soap with water mix- 

 ture is a mobile liquid. The first additions of potassium hydroxid 

 to this mixture serve to increase its viscosity as evidenced in the 

 tubes marked 1, 2, 3 and 4. But beyond this point further 

 addition of the potassium hydroxid begins to bring about a 

 dehydration of the soap which increases progressively until, in 

 the tube marked 10, the soap is found floating as a thin layer 

 at the top of the clear dispersion medium. 



The effects of sodium hydroxid upon the standard potassium 

 oleate are similar to those of potassium hydroxid as apparent in 



1 See page 77 for a discussion of the meaning of indicator methods when 

 applied to these soap systems. 



