2 AES. 4.— T. KAMETAKA : 



clear oil thus obtained was directly used for the following deter- 

 mination of the iodine value. 



0.1489 gr. of the oil was dissolved in 10 c.c. of chloroform, 

 and 25 c.c. of Hübl's solution was added. After standing for 

 about 24 hours in the dark, the excess of iodine was titrated back 

 with standard thiosulphate solution (1 c.c. =0.01231 gr. iodine), 

 of which 29.3 c.c. was required, whilst in a blank experiment 

 48.7 c.c. of the thiosulphate solution was required. The iodine 

 value is, therefore, 



(48.7 - 29.3) X 0.01231 x 100 ^ ^^ o 

 ^ Ö1489 — = lß0.3 



Two other such experimints gave 160.8 and 162.8, so that the 

 mean of the three experiments was 161.3. 



After storing the cold-drawn oil in an ordinary stoppered 

 bottle in the dark for eleven months, its iodine value was re- 

 determined according to Hübl's method. The results were 149.3 

 and 150.6, mean 150.0, so that during the eleven months the 

 iodine value of the oil had decreased by 161.3—150.0 = 11.3. Mean- 

 while, the iodine value of the oil was also determined according 

 to WiJis' method. Wuis' solution was prepared as follows : — 



12.7 gr. of iodine was dissolved in one litre of glacial acetic 

 acid ; to this solution dried chlorine gas was passed until a 

 sudden change in colour occurred. The solution was warmed on 

 a water-bath, and the excess of chlorine changed into chloracetic 

 acid. Using this solution the iodine value was determined in 

 the same manner as in Hübl's method, but the time of standing- 

 was only 3-4 hours. The results of two experiments made with 

 the cold-drawn oil, which has been stored in an ordinary stop- 

 pered bottle in the dark for three months, were 155.7 and 156.8, 

 mean 156.3. 



