Eobertson. — Distillation of Fatty Acids. 



571 





the distiller knows that the product is at first soft. It then 

 opens out and becomes harder and harder. Towards the end 



JTJ 3 



S&3 



4f 



•Fis-joCoU *.3&corLa!-CoU> 





AT +5 S3 



of the operation it becomes brown in colour, and begins to 

 soften once more. 



It is generally stated that the freezing-point gradually 

 rises and then falls rapidly. The initial fall and the final rise 

 appear to have been unnoticed by former observers. Further, 

 the results obtained from the different coils are of distinct in- 

 terest, and in fact have been found to be of great assistance 

 in understanding the nature of the changes that occur. How- 

 ever, a complete analysis was necessary to ascertain the varia- 

 tion of the composition of the products obtained throughout 

 the investigation. The different samples were analysed by 

 means of the following methods : — 



The oleic acid was estimated by finding the amount of 

 iodine absorbed according to the method of Hiibl. The iodine- 

 solution was made by dissolving 25 grams of iodine and 30 

 grams of mercuric chloride in 95 per cent, alcohol. This was 

 standardised against N/10 sodium-thiosulphate solution, the 

 strength of which was known accurately by comparison with 

 deci-normal potassium-bichromate. 



About 1 gram of the substance to be analysed was dis- 

 solved in 10 c.c. of chloroform and transferred to a large 

 stoppered bottle. 25 c.c. of the iodine-solution was run in 

 and the mixture was left, with occasional shaking, for two 

 hours. At the end of that time 20 c.c. of 10-per-cent. potas- 



