48 FORESTRY OF WEST AFRICA. 



The proportion of water and impurities in the 're- 

 gular ' oils varies from under one per cent, (this is 

 rare) to 7 or 8 per cent., but rarely exceeds 5 or 6 

 per cent. In the ' irregular ' oils, water and impurities 

 are frequently as high as 16 or 18 per cent, and some- 

 times even so much as 25 or 30 per cent. ; but most of 

 the irregular samples run from about 5 to 10 or 12 

 per cent. 



" The oil itself when fresh consists chiefly of the 

 fatty bodies known as tripalmitin, a compound of 

 palmitic acid and glycerol, or glycerin, and triolein, a 

 compound of oleic acid and glycerol, or glycerin, the 

 tripalmitin being present in greater quantity. There 

 are also present in most specimens of the oil free fatty 

 acids, and these increase in quantity as the oil becomes 

 older. 



' " The oil is largely used for soap-makiag, and 

 generally in combination with tallow and other fats. 

 And by processes of saponification, or treatment at 

 high temperature with super-heated steam, its con- 

 stituents are separated into a solid fatty acid, palmi- 

 tic acid (often mixed with other solid fatty acids), a 

 liquid oily body, oleic acid, and glycerin. The solid 

 fats are largely used for candle-making, whilst the 

 oleic acid is employed for lubricating and many other 

 purposes for which the liquid oils, such as olive, are 

 used. The glycerin when refined is made use of in 

 medicine, surgery, for the manufacture of the ex- 

 plosive nitro-glycerin, and many other purposes. 



