572 



Transactions. — Physics. 



sium- iodide solution and 400 c.c. of water were added. The 

 excess of iodine was then determined by means of the sodium- 

 thiosulphate. The oleic acid was thus determined by differ- 

 ence. 



The experimental results are given in Table II. It is seen 

 that the percentage of oleic acid rapidly rises but finally be- 

 comes almost constant. More detailed experiments (series 2) 

 show that after the maximum has been reached there is a 

 slight fall, but at the extreme end of the operation the 



amount again increases. 



Table II. — Oleic Acid. 

 Distillation, May, 1903. 



The total acid was determined by titrating with N/20 soda 

 in alcoholic solution, using phenolphthalein as the indicator. 

 It was found convenient to standardise the alkali against 

 pure stearic acid under exactly the same conditions. The 

 amount of oleic acid is already known, and from the rela- 

 tions — 



1 c.c. N/20 soda = 0128 gram palmitic acid, 

 = 0141 „ oleic acid, 

 = 0-142 „ stearic acid, 



the amounts of palmitic and stearic acids could be calculated 



indirectly. When the result is greater than 0112, then the 



