512 FIXED OILS, FATS AND WAXES 



2 c.c. of the oil with 1 c.c. of a (freshly prepared) 1 per cent, solution 

 of sucrose (or furfurol) in hydrochloric acid when a pink colour results. 



Uses. As a substitute for olive oil ; for making margarine and 

 also in the preparation of additive compounds with iodine and 

 bromine. 



CROTON OIL 



(Oleum Crotonis) 



Source, &c. The oil expressed from the seeds of Croton Tiglium, 

 Linne (N.O. Euphorbiacece) . See p. 184. 



Description, &c. A brownish yellow to dark reddish brown, 

 viscous, slightly fluorescent oil with a disagreeable odour and intensely 

 acrid taste, blistering the skin and mucous membrane. Specific 

 gravity 0-940 to 0-960 ; iodine value 102 to 106 ; miscible with half 

 its volume of absolute alcohol ; thickens slightly but does not solidify, 

 either partially or completely when shaken with half its volume 

 of fuming nitric acid and the same proportion of water. It consists 

 of the glycerides of stearic, palmistic, myristic, lauric, valerianic, 

 tiglic and other acids and contains the acrid principle croton-resin. 



Uses. An extremely powerful cathartic, counter-irritant and 

 vesicant. 



CASTOR OIL 



(Oleum Ricini) 



Source, &C. The oil expressed from the seeds of Eicinus communis, 

 Linne (N.O. Euphorbiacece). See p. 182. 



Description, &C. Nearly colourless, viscous, slight odour, acrid 

 unpleasant taste. Specific gravity 0'958 to 0'970 ; iodine value 

 83 to 90 ; acetyl value about 150 ; soluble in all proportions in 

 absolute alcohol and in 3-5 parts of alcohol (90 per cent.) ; consists 

 of the glycerides of ricinoleic, isoricinoleic, stearic and dihydroxy- 

 stearic acids. Its freedom from admixture with other fixed oils is 

 shown by the petroleum spirit test : 10 c.c. with 7 c.c. of petroleum 

 spirit form a clear mixture at 15'5 ; on adding a further 3 c.c. of 

 petroleum spirit the mixture becomes turbid, on warming to 21 clear, 

 and on cooling to 18 again cloudy. 



Uses. A mild purgative ; on account of its viscosity largely used, 

 especially in warm climates, as a lubricant. 



Note. Turkey red oil is obtained by allowing sulphuric acid to run slowly 

 into castor oil, kept cool, washing with water and solution of sodium sulphate 

 and adding ammonia until a clear water-soluble liquid is formed ; the ricinoleic 

 acid is converted into ricinoleo -sulphuric acid. It is largely used in dyeing 

 cotton, imparting to the fabric a better lustre. 



