4 FATS, OILS, AND WAXES 



a faint odour resembling that of violets. Both coco-nut oil 

 and palm oil in the crude state contain free fatty acids which 

 can, however, be removed by treatment with alcohol. When 

 so purified they are employed as substitutes for butter under 

 the name of vegetable butter or palmine, etc. 



RAPE OIL or COLZA OIL is a thick, yellowish oil obtained 

 from the seeds of Brassica Rapa and Brassica Napus which is 

 used as an illuminant. 



By drawing a current of air through the oil heated to 70 

 a so-called "blown" oil is produced, the specific gravity of 

 which becomes almost equal to that of castor oil, namely 

 O'97 ; in this condition it is miscible with mineral oils. The 

 mixture which is known as marine oil is used for lubricating 

 marine engines. 



LlNSEED OIL is obtained by pressing the seeds of Linum 

 usitatissimum either with or without the application of heat ; 

 the residues after compression are made up into cattle food. 



The drying vegetable oils, particularly linseed oil, are used 

 in the manufacture of oil paints as vehicles for the pigments ; 

 for artist's white paints, walnut and poppy-seed oils are chiefly 

 used. The drying properties of linseed oil used for the manu- 

 facture of paint are greatly increased by boiling with lead 

 oxide ; such oil is known as boiled oil. A similar effect may 

 be produced by dissolving in it certain salts known as "driers," 

 such as lead linoleate or the metallic salts of resin acids, etc. 



Varnish consists of a mixture of boiled oil with gum resins 

 and oil of turpentine. 



CASTOR OIL is obtained by compressing the seeds of 

 Ricinus communis either with or without the application of 

 heat. The seeds contain a fat-splitting enzyme which is em- 

 ployed commercially for the hydrolysis of fats ; they also 

 contain a very poisonous toxalbumin, known as Ricin, which 

 remains in the residues after the expression of the oil. Castor 

 oil is a thick viscid colourless liquid ; when heated above 280 

 it decomposes with the formation of oenanthol, a substance 

 having a very unpleasant odour. Castor oil is largely used in 

 the dye industry ; for this purpose it is converted into the so- 

 called turkey red oil, used for alizarin dyeing, by treatment 

 with sulphuric acid and neutralization of the resulting sulphonic 

 acid with soda. 



