OLIVE OIL 511 



By saponification these compounds yield respectively oleic, palmitic, 

 linolic, and arachic acids together with glycerin v 



Uses. Olive oil has nutritive and laxative properties. Applied 

 externally it is emollient and soothing. 



Adulterants. Valuable indications of purity are to be found in 

 the specific gravity (0-915 to 0-918) and in the iodine value (79 to 

 87). The free acid present should not exceed 1 per cent., calculated 

 as oleic acid, lower qualities may contain up to 5 per cent, of acid, 

 and oils for technical purposes as much as 30 per cent. Cotton-seed 

 oil, a frequent adulterant, is best detected by Halphen's (Bevan's) test 

 which consists inlHlrming 2 c.c. of the oil mixed with 1 c.c. of amylic 

 alcohol and 1 c.c. of a 1 per cent, solution of sulphur in carbon 

 disulphide for ten linutes in a water-bath when no red colour should 

 be developed. 



Sesame oil [from the seeds of Sesdmum indicum, Linne (N.O. 

 Pedalinece), India] is tested for by mixing 2 c.c. with 1 c.c. of 

 hydrochloric acid containing 1 per cent, of sucrose, shaking for half 

 an hour, adding 3 c.c. of water, again shaking and setting aside, 

 when the aqueous liquid should not become pink. 



The oil expressed from the seeds of the tea plant (tea seed oil) 

 closely resembles olive oil and is said to be used for adulterating it. 



For details of other tests for ascertaining the purity of olive oil, 

 reference should be made to works on analytical chemistry, such as 

 Allen's ' Commercial Organic Analysis,' or Lewkowitsch, ' Chemical 

 Technology and Analysis of Oil, Fats and Waxes.' 



SESAME OIL 

 (Gingelly Oil, Teel Oil, Benne Oil, Oleum Sesami) 



Source, &c. Sesame oil is the oil expressed from the seeds of 

 Sesdmum indicum, Linne (N.O. Pedalinece), an annual plant about 

 1 m. high, extensively cultivated in India, China, Japan and most 

 tropical countries. The seeds are small, 1-5 to 4 mm. long, 1 to 2 mm. 

 broad and 1 mm. thick, yellowish white, reddish, brown or black 

 according to the variety, obovate, slightly pointed, with four narrow 

 longitudinal ribs. They contain about 50 per cent, of fixed oil and 

 about 15 per cent, of proteids but no starch. 



Description, &c. Pale to golden yellow. Specific gravity 0-921 

 to 0-924 ; iodine value 103 to 114 ; congeals at about 5 ; consists 

 of the glycerides of oleic, linolic, palmitic, stearic and myristic acids ; 

 contains about 0-2 to 0-5 per cent, of sesamin (acicular crystals, 

 melting at 118), also sesamol (phenolic) and a substance producing 

 the characteristic colour reaction ; may be identified by shaking 



