32 FATS, OILS, AND WAXES 



Cotton-seed Oil is extracted from the seeds of Gossypium 

 herbaceum by pressing them at a temperature of about 90° ; 

 the crude brown oil is purified by treatment with caustic soda, 

 which removes the free fatty acids, colouring matter, and other 

 impurities. After purification the oil is light yellow in colour. 

 It is used for the manufacture of soap and rubber substitutes. 



Coco-nut Oil is obtained from the ripe seeds of Cocos 

 nucifera and Cocos butyracea by pressure ; the dried endo- 

 sperms, known as Copra, are imported into Europe, and the 

 oil extracted from them is commonly known as Copra oil. 

 Soaps made from coco-nut oil have the property of absorbing 

 large quantities of salt solutions, and can therefore be used for 

 washing with sea water. 



Palm Oil which occurs in the fruit of Elaeis guineensis is, 

 when pure, a colourless substance of the consistency of lard ; 

 on exposure to air it readily turns yellow, but the colour can 

 be removed by oxidation by means of a current of air. 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 in the manu- 

 facture of margarine. 



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 

 0'97 ; in this condition it is miscible with mineral oils. The 

 mixture which is known as marine oil is used for lubricating 

 marine engines. 



Linseed 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 some- 

 times used. The drying properties of linseed oil used for the 

 manufacture of paint are greatly increased by boiling with lead 



