508 FIXED OILS, FATS AND WAXES 



oil. They also contain a crystalline yellow substance of phenolic 

 nature (gossypol) which passes into the (cold pressed) oil, but is ex- 

 tracted from it by alkalies which are always used in refining the oil. 



Description, &c. The crude oil expressed from the seeds is dark 

 in colour, but after refining by a partial saponification it is pale yellow, 

 odourless and of agreeable nutty taste. Specific gravity 0'918 to 

 0-925 ; begins to congeal at about 12 ; iodine value 102 to 108 ; consists 

 chiefly of the glycerides of oleic, palmitic, linolic and stearic acids. 

 It may be identified by heating in a water-bath a mixture of 2 c.c. 

 of the oil with 1 c.c. of amyl alcohol and 1 c.c. of a 1 per cent, solution 

 of sulphur in carbon disulphide when a deep red colour is developed 

 except in the case of oil which has been further purified by heating to 

 200. Cotton-seed oil is largely used for making margarine and the 

 lower qualities for soap. 



OIL OF THEOBROMA 



(Cocoa Butter, Oleum Theobromatis, Butyrum Cacao) 



Source, &C. The solid fat expressed from the seeds of Theobroma 

 Cacao, Linne (N.O. Sterculiacece) . See p. 153. 



Description, &c. Hard, brittle, pale yellow ; softens at about 

 25 ; melting-point 30 to 33 ; specific gravity 0-990 to 0-998 ; iodine 

 value 35-5 to 37-5. Consists of stearic, palmitic, arachic, oleic and 

 small quantities of other acids combined with glycerol, partly as 

 triglycerides, partly as mixed glycerides in which two fatty acids 

 are combined with one glyceryl group. Chiefly used in pharmacy as 

 a basis for suppositories, pessaries, &c. 



Note. Shea butter is a greyish fat of characteristic aromatic odour obtained 

 from the seeds of Butyrospermum Parkii, Klotschy (N.O. Sapotacece), North 

 Africa. Kokum butter from the seeds of Garcinia indica, Choisy (N.O. Guttiferce), 

 is largely used in India. Illipe or mahua butter is obtained by expression from 

 the seeds of Bassia latifolia, Roxburgh, and Bassia tallow from the seeds of B. 

 longifolia, Willdenow (N.O. Sapotacece) ; both are used for making candles and 

 soap. Chinese vegetable tallow is the fat on the outside of the seed of Stillingia 

 sebifera, Mich. (N.O. Euphorbiacece) ; it is largely used in China for making 

 candles. 



LINSEED OIL 



(Oleum Lini) 



Source, &C. The oil expressed from the seeds of Linum usitatis- 

 simum, Linn6 (N.O. Lintce). (Compare ' Linseed,' p. 149.) 



Description. Yellowish-brown, with characteristic odour ; specific 

 gravity 0-930 to 0-940 ; iodine value not less than 170 ; unsaponifiable 

 matter not more than 1 per cent. ; does not congeal at temperatures 



